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  Subjects -> CHEMISTRY (Total: 931 journals)
    - ANALYTICAL CHEMISTRY (58 journals)
    - CHEMISTRY (663 journals)
    - CRYSTALLOGRAPHY (21 journals)
    - ELECTROCHEMISTRY (27 journals)
    - INORGANIC CHEMISTRY (43 journals)
    - ORGANIC CHEMISTRY (48 journals)
    - PHYSICAL CHEMISTRY (71 journals)

CHEMISTRY (663 journals)                  1 2 3 4 | Last

Showing 1 - 200 of 735 Journals sorted alphabetically
2D Materials     Hybrid Journal   (Followers: 15)
Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement     Hybrid Journal   (Followers: 31)
ACS Applied Polymer Materials     Hybrid Journal  
ACS Catalysis     Hybrid Journal   (Followers: 55)
ACS Chemical Neuroscience     Hybrid Journal   (Followers: 22)
ACS Combinatorial Science     Hybrid Journal   (Followers: 21)
ACS Macro Letters     Hybrid Journal   (Followers: 29)
ACS Medicinal Chemistry Letters     Hybrid Journal   (Followers: 46)
ACS Nano     Hybrid Journal   (Followers: 378)
ACS Photonics     Hybrid Journal   (Followers: 15)
ACS Symposium Series     Full-text available via subscription   (Followers: 1)
ACS Synthetic Biology     Hybrid Journal   (Followers: 25)
Acta Chemica Iasi     Open Access   (Followers: 6)
Acta Chimica Slovaca     Open Access   (Followers: 2)
Acta Chimica Slovenica     Open Access   (Followers: 1)
Acta Chromatographica     Full-text available via subscription   (Followers: 8)
Acta Facultatis Medicae Naissensis     Open Access  
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 7)
Acta Scientifica Naturalis     Open Access   (Followers: 2)
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 8)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 9)
Adsorption Science & Technology     Open Access   (Followers: 7)
Advanced Functional Materials     Hybrid Journal   (Followers: 65)
Advanced Science Focus     Free   (Followers: 5)
Advances in Chemical Engineering and Science     Open Access   (Followers: 88)
Advances in Chemistry     Open Access   (Followers: 29)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 20)
Advances in Drug Research     Full-text available via subscription   (Followers: 26)
Advances in Environmental Chemistry     Open Access   (Followers: 8)
Advances in Enzyme Research     Open Access   (Followers: 11)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 9)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 17)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 11)
Advances in Materials Physics and Chemistry     Open Access   (Followers: 29)
Advances in Nanoparticles     Open Access   (Followers: 19)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 18)
Advances in Polymer Science     Hybrid Journal   (Followers: 49)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 19)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 20)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 6)
Advances in Science and Technology     Full-text available via subscription   (Followers: 13)
Aerosol Science and Engineering     Hybrid Journal  
African Journal of Bacteriology Research     Open Access  
African Journal of Chemical Education     Open Access   (Followers: 5)
African Journal of Pure and Applied Chemistry     Open Access   (Followers: 8)
Agrokémia és Talajtan     Full-text available via subscription   (Followers: 2)
Al-Kimia : Jurnal Penelitian Sains Kimia     Open Access  
Alchemy : Journal of Chemistry     Open Access   (Followers: 3)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 2)
Alotrop     Open Access  
AMB Express     Open Access   (Followers: 1)
Ambix     Hybrid Journal   (Followers: 3)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 71)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 22)
American Journal of Chemistry     Open Access   (Followers: 35)
American Journal of Plant Physiology     Open Access   (Followers: 13)
American Mineralogist     Hybrid Journal   (Followers: 14)
Anadolu University Journal of Science and Technology A : Applied Sciences and Engineering     Open Access  
Analyst     Full-text available via subscription   (Followers: 37)
Angewandte Chemie     Hybrid Journal   (Followers: 191)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 289)
Annales Universitatis Mariae Curie-Sklodowska, sectio AA – Chemia     Open Access   (Followers: 1)
Annals of Clinical Chemistry and Laboratory Medicine     Open Access   (Followers: 4)
Annual Reports in Computational Chemistry     Full-text available via subscription   (Followers: 3)
Annual Reports Section A (Inorganic Chemistry)     Full-text available via subscription   (Followers: 4)
Annual Reports Section B (Organic Chemistry)     Full-text available via subscription   (Followers: 8)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 12)
Annual Review of Food Science and Technology     Full-text available via subscription   (Followers: 15)
Antiviral Chemistry and Chemotherapy     Open Access   (Followers: 2)
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 9)
Applied Spectroscopy     Full-text available via subscription   (Followers: 26)
Applied Surface Science     Hybrid Journal   (Followers: 33)
Arabian Journal of Chemistry     Open Access   (Followers: 6)
ARKIVOC     Open Access   (Followers: 1)
Asian Journal of Biochemistry     Open Access   (Followers: 3)
Asian Journal of Chemistry and Pharmaceutical Sciences     Open Access   (Followers: 2)
Atomization and Sprays     Full-text available via subscription   (Followers: 5)
Australian Journal of Chemistry     Hybrid Journal   (Followers: 7)
Autophagy     Hybrid Journal   (Followers: 4)
Avances en Quimica     Open Access  
Biochemical Pharmacology     Hybrid Journal   (Followers: 11)
Biochemistry     Hybrid Journal   (Followers: 403)
Biochemistry Insights     Open Access   (Followers: 7)
Biochemistry Research International     Open Access   (Followers: 7)
BioChip Journal     Hybrid Journal  
Bioinorganic Chemistry and Applications     Open Access   (Followers: 11)
Bioinspired Materials     Open Access   (Followers: 5)
Biointerface Research in Applied Chemistry     Open Access   (Followers: 2)
Biointerphases     Open Access   (Followers: 1)
Biology, Medicine, & Natural Product Chemistry     Open Access   (Followers: 2)
Biomacromolecules     Hybrid Journal   (Followers: 25)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 10)
Biomedical Chromatography     Hybrid Journal   (Followers: 6)
Biomolecular NMR Assignments     Hybrid Journal   (Followers: 3)
BioNanoScience     Partially Free   (Followers: 6)
Bioorganic & Medicinal Chemistry     Hybrid Journal   (Followers: 184)
Bioorganic & Medicinal Chemistry Letters     Hybrid Journal   (Followers: 91)
Bioorganic Chemistry     Hybrid Journal   (Followers: 10)
Biopolymers     Hybrid Journal   (Followers: 17)
Biosensors     Open Access   (Followers: 3)
Biotechnic and Histochemistry     Hybrid Journal   (Followers: 1)
Bitácora Digital     Open Access  
Boletin de la Sociedad Chilena de Quimica     Open Access  
Bulletin of Institute of Chemistry and Chemical Technology, Mongolian Academy of Sciences     Open Access  
Bulletin of the Chemical Society of Ethiopia     Open Access   (Followers: 1)
Bulletin of the Chemical Society of Japan     Full-text available via subscription   (Followers: 25)
Bulletin of the Korean Chemical Society     Hybrid Journal   (Followers: 1)
C - Journal of Carbon Research     Open Access   (Followers: 3)
Cakra Kimia (Indonesian E-Journal of Applied Chemistry)     Open Access  
Canadian Association of Radiologists Journal     Full-text available via subscription   (Followers: 2)
Canadian Journal of Chemistry     Hybrid Journal   (Followers: 12)
Canadian Mineralogist     Full-text available via subscription   (Followers: 7)
Carbohydrate Research     Hybrid Journal   (Followers: 24)
Carbon     Hybrid Journal   (Followers: 73)
Catalysis for Sustainable Energy     Open Access   (Followers: 10)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 10)
Catalysis Science and Technology     Hybrid Journal   (Followers: 10)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysts     Open Access   (Followers: 14)
Cellulose     Hybrid Journal   (Followers: 14)
Cereal Chemistry     Full-text available via subscription   (Followers: 5)
ChemBioEng Reviews     Full-text available via subscription   (Followers: 2)
ChemCatChem     Hybrid Journal   (Followers: 8)
Chemical and Engineering News     Free   (Followers: 23)
Chemical Bulletin of Kazakh National University     Open Access  
Chemical Communications     Full-text available via subscription   (Followers: 76)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 27)
Chemical Physics Letters : X     Open Access   (Followers: 2)
Chemical Research in Chinese Universities     Hybrid Journal   (Followers: 3)
Chemical Research in Toxicology     Hybrid Journal   (Followers: 23)
Chemical Reviews     Hybrid Journal   (Followers: 233)
Chemical Science     Open Access   (Followers: 33)
Chemical Technology     Open Access   (Followers: 49)
Chemical Vapor Deposition     Hybrid Journal   (Followers: 5)
Chemie in Unserer Zeit     Hybrid Journal   (Followers: 56)
Chemie-Ingenieur-Technik (Cit)     Hybrid Journal   (Followers: 21)
ChemInform     Hybrid Journal   (Followers: 8)
Chemistry     Open Access  
Chemistry & Biodiversity     Hybrid Journal   (Followers: 7)
Chemistry & Biology     Full-text available via subscription   (Followers: 32)
Chemistry & Industry     Full-text available via subscription   (Followers: 8)
Chemistry - A European Journal     Hybrid Journal   (Followers: 191)
Chemistry - An Asian Journal     Hybrid Journal   (Followers: 17)
Chemistry Africa : A Journal of the Tunisian Chemical Society     Hybrid Journal  
Chemistry and Materials Research     Open Access   (Followers: 22)
Chemistry Central Journal     Open Access   (Followers: 4)
Chemistry Education Research and Practice     Free   (Followers: 5)
Chemistry in Education     Open Access   (Followers: 9)
Chemistry International     Open Access   (Followers: 3)
Chemistry Letters     Full-text available via subscription   (Followers: 46)
Chemistry of Heterocyclic Compounds     Hybrid Journal   (Followers: 4)
Chemistry of Materials     Hybrid Journal   (Followers: 284)
Chemistry of Natural Compounds     Hybrid Journal   (Followers: 10)
Chemistry World     Full-text available via subscription   (Followers: 21)
Chemistry-Didactics-Ecology-Metrology     Open Access   (Followers: 1)
ChemistryOpen     Open Access   (Followers: 1)
Chemkon - Chemie Konkret, Forum Fuer Unterricht Und Didaktik     Hybrid Journal  
Chemoecology     Hybrid Journal   (Followers: 3)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 15)
Chemosensors     Open Access  
ChemPhysChem     Hybrid Journal   (Followers: 12)
ChemPlusChem     Hybrid Journal   (Followers: 2)
ChemTexts     Hybrid Journal  
CHIMIA International Journal for Chemistry     Full-text available via subscription   (Followers: 2)
Chinese Journal of Chemistry     Hybrid Journal   (Followers: 6)
Chinese Journal of Polymer Science     Hybrid Journal   (Followers: 12)
Chromatographia     Hybrid Journal   (Followers: 22)
Chromatography     Open Access   (Followers: 3)
Chromatography Research International     Open Access   (Followers: 5)
Clay Minerals     Hybrid Journal   (Followers: 10)
Cogent Chemistry     Open Access   (Followers: 2)
Colloid and Interface Science Communications     Open Access  
Colloid and Polymer Science     Hybrid Journal   (Followers: 11)
Colloids and Interfaces     Open Access  
Colloids and Surfaces B: Biointerfaces     Hybrid Journal   (Followers: 8)
Combinatorial Chemistry & High Throughput Screening     Hybrid Journal   (Followers: 4)
Combustion Science and Technology     Hybrid Journal   (Followers: 24)
Comments on Inorganic Chemistry: A Journal of Critical Discussion of the Current Literature     Hybrid Journal   (Followers: 2)
Communications Chemistry     Open Access   (Followers: 2)
Composite Interfaces     Hybrid Journal   (Followers: 8)
Comprehensive Chemical Kinetics     Full-text available via subscription   (Followers: 1)
Comptes Rendus Chimie     Full-text available via subscription  
Comptes Rendus Physique     Full-text available via subscription   (Followers: 2)
Computational and Theoretical Chemistry     Hybrid Journal   (Followers: 9)
Computational Biology and Chemistry     Hybrid Journal   (Followers: 13)
Computational Chemistry     Open Access   (Followers: 3)
Computers & Chemical Engineering     Hybrid Journal   (Followers: 10)
Coordination Chemistry Reviews     Full-text available via subscription   (Followers: 4)
Copernican Letters     Open Access   (Followers: 1)
Corrosion Series     Full-text available via subscription   (Followers: 7)
Critical Reviews in Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 8)
Croatica Chemica Acta     Open Access  
Crystal Structure Theory and Applications     Open Access   (Followers: 4)
CrystEngComm     Full-text available via subscription   (Followers: 13)
Current Catalysis     Hybrid Journal   (Followers: 2)
Current Chromatography     Hybrid Journal  
Current Green Chemistry     Hybrid Journal   (Followers: 2)
Current Metabolomics     Hybrid Journal   (Followers: 6)
Current Microwave Chemistry     Hybrid Journal  
Current Opinion in Colloid & Interface Science     Hybrid Journal   (Followers: 10)

        1 2 3 4 | Last

Similar Journals
Journal Cover
Catalysts
Number of Followers: 14  

  This is an Open Access Journal Open Access journal
ISSN (Online) 2073-4344
Published by MDPI Homepage  [222 journals]
  • Catalysts, Vol. 9, Pages 875: A 2.5D Electrode System Constructed of
           Magnetic Sb–SnO2 Particles and a PbO2 Electrode and Its Electrocatalysis
           Application on Acid Red G Degradation

    • Authors: Yuan, Salman, Guo, Xu, Xu, Yan, Liao, Wang
      First page: 875
      Abstract: A novel electrode consisting of a Ti/PbO2 shell and Fe3O4/Sb–SnO2 particles was developed for electrochemical oxidation treatment of wastewater. Scanning electron microscope (SEM), X-ray diffraction (XRD), the current limiting method, toxicity experiments, and high-performance liquid chromatography were adopted to characterize its morphology, crystal structure, electrochemical properties, the toxicity of the wastewater, and hydroxyl radicals. Acid Red G (ARG), a typical azo dye, was additionally used to test the oxidation ability of the electrode. Results indicated that the 2.5D electrode could significantly improve the mass transfer coefficient and •OH content of the 2D electrode, thereby enhancing the decolorization, degradation, and mineralization effect of ARG, and reducing the toxicity of the wastewater. The experiments revealed that, at higher current density, lower dye concentration and higher temperature, the electrochemical oxidation of ARG favored. Under the condition of 50 mA/cm2, 25 °C, and 100 ppm, the ARG, Chemical Oxygen Demand (COD) and Total Organic Carbon (TOC) removal efficiency reached 100%, 65.89%, and 52.52%, respectively, and the energy consumption and the current efficiency were 1.06 kWh/g COD, 8.29%, and energy consumption for TOC and mineralization current efficiency were 3.81 kWh/g COD, 9.01%. Besides, the Fe3O4/Sb–SnO2 particles after electrolysis for 50 h still had remarkable stability. These results indicated that the ARG solution could be adequately removed on the 2.5D electrode, providing an effective method for wastewater treatment.
      Citation: Catalysts
      PubDate: 2019-10-23
      DOI: 10.3390/catal9110875
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 876: Photocatalytic Degradation of Atenolol by
           TiO2 Irradiated with an Ultraviolet Light Emitting Diode: Performance,
           Kinetics, and Mechanism Insights

    • Authors: Ran, Wang, Fang, Ma, Li
      First page: 876
      Abstract: Batch experiments were performed to investigate the effect of several environmental factors on atenolol (ATL) degradation efficiency, including catalyst crystal phase (anatase TiO2, rutile TiO2, and mixed phase), catalyst dosage, UV-LED wavelength and intensity, co-existing anions, cations, and pH. The mixed phase (2 g/L) exhibited the best photocatalytic activity at 365 nm, with ATL (18.77 µM) completely oxidized within 1 h. These results suggest that: (i) The mixed phase exhibits the highest activity due to its large specific surface area and excellent charge separation efficiency. (ii) ATL can be effectively degraded using mixed phase TiO2 combined with UV-LED technology and the ATL degradation efficiency could reach 100% for 60 min; (iii) ATL photodegradation was more effective under 365 nm UV-LED than 254 nm, which was caused by the effect of light-induced charge separation; (iv) the ATL Degradation efficiency(De) decreased with an increase in initial ATL concentrations; and (v) co-existing anions and cations had different effects on the ATL De, mainly by changing the concentration of hydroxyl radicals. Considering that UV-LED is more energy-saving and environmentally friendly, and commercial TiO2 is cheap and easy to obtain, our research provides feasibility for practical application.
      Citation: Catalysts
      PubDate: 2019-10-23
      DOI: 10.3390/catal9110876
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 877: A Comparative Study of Microcystin-LR
           Degradation by UV-A, Solar and Visible Light Irradiation Using Bare and
           C/N/S-Modified Titania

    • Authors: Khedr, El-Sheikh, Abdeldayem, Ismail, Kowalska, Bahnemann
      First page: 877
      Abstract: In an endeavor to tackle environmental problems, the photodegradation of microcystin-LR (MC-LR), one of the most common and toxic cyanotoxins, produced by the cyanobacteria blooms, was examined using nanostructured TiO2 photocatalysts (anatase, brookite, anatase–brookite, and C/N/S co-modified anatase–brookite) under UV-A, solar and visible light irradiation. The tailoring of TiO2 properties to hinder the electron–hole recombination and improve MC-LR adsorption on TiO2 surface was achieved by altering the preparation pH value. The highest photocatalytic efficiency was 97% and 99% with degradation rate of 0.002 mmol L−1 min−1 and 0.0007 mmol L−1 min−1 under UV and solar irradiation, respectively, using a bare TiO2 photocatalyst prepared at pH 10 with anatase to brookite ratio of ca. 1:2.5. However, the bare TiO2 samples were hardly active under visible light irradiation (25%) due to a large band gap. Upon UV, solar and vis irradiation, the complete MC-LR degradation (100%) was obtained in the presence of C/N/S co-modified TiO2 with a degradation rate constant of 0.26 min−1, 0.11 min−1 and 0.04 min−1, respectively. It was proposed that the remarkable activity of co-modified TiO2 might originate from its mixed-phase composition, mesoporous structure, and non-metal co-modification.
      Citation: Catalysts
      PubDate: 2019-10-23
      DOI: 10.3390/catal9110877
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 878: Editorial: Special Issue “New Concepts in
           Oxidation Processes”

    • Authors: Genty, Bustillo-Lecompte, Colina-Márquez, Barroo, Cousin
      First page: 878
      Abstract: Oxidation processes, as part of the catalysis field, play a significant role in both industrial chemistry and environmental protection [...]
      Citation: Catalysts
      PubDate: 2019-10-23
      DOI: 10.3390/catal9110878
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 879: Cooperative Catalytic Behavior of SnO2 and
           NiWO4 over BiVO4 Photoanodes for Enhanced Photoelectrochemical Water
           Splitting Performance

    • Authors: Maged N. Shaddad, Prabhakarn Arunachalam, Mahmoud Hezam, Abdullah M. Al-Mayouf
      First page: 879
      Abstract: n-BiVO4 is a favorable photoelectrode candidate for a photoelectrochemical (PEC) water splitting reaction owing to its suitable energy level edge locations for an oxygen evolution reaction. On the other hand, the sluggish water oxidation kinetics of BiVO4 photoanodes when used individually make it necessary to use a hole blocking layer as well as water oxidation catalysts to overcome the high kinetic barrier for the PEC water oxidation reaction. Here, we describe a very simple synthetic strategy to fabricate nanocomposite photoanodes that synergistically address both of these critical limitations. In particular, we examine the effect of a SnO2 buffer layer over BiVO4 films and further modify the photoanode surface with a crystalline nickel tungstate (NiWO4) nanoparticle film to boost PEC water oxidation. When NiWO4 is incorporated over BiVO4/SnO2 films, the PEC performance of the resultant triple-layer NiWO4/BiVO4/SnO2 films for the oxygen evolution reaction (OER) is further improved. The enhanced performance for the PEC OER is credited to the synergetic effect of the individual layers and the introduction of a SnO2 buffer layer over the BiVO4 film. The optimized NiWO4/BiVO4/SnO2 electrode demonstrated both enriched visible light absorption and achieves charge separation and transfer efficiencies of 23% and 30%, respectively. The photoanodic current density for the OER on optimized NiWO4/BiVO4/SnO2 photoanode shows a maximum photocurrent of 0.93 mA/cm2 at 1.23 V vs. RHE in a phosphate buffer solution (pH~7.5) under an AM1.5G solar simulator, which is an incredible five-fold and two-fold enhancement compared to its parent BiVO4 photoanode and BiVO4/SnO2 photoanodes, respectively. Further, the incorporation of the NiWO4 co-catalyst over the BiVO4/SnO2 film increases the interfacial electron transfer rate across the composite/solution interface.
      Citation: Catalysts
      PubDate: 2019-10-23
      DOI: 10.3390/catal9110879
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 880: Enhanced Performance of Electrospun
           Nanofibrous TiO2/g-C3N4 Photocatalyst in Photocatalytic Degradation of
           Methylene Blue

    • Authors: Feidias Bairamis, Ioannis Konstantinou, Dimitrios Petrakis, Tiverios Vaimakis
      First page: 880
      Abstract: TiO2/g-C3N4 (GNT) fibers with 1%, 2.5% and 5% (wt%) ratios have been synthesized via one-step electrospinning using polyvinylpyrrolidone (PVP) polymer. Results showed mesoporous fibrous catalysts consisted of anatase (80.0–85.1%) and rutile phase (14.9–20.0%), with diameter between 200–300 nm and band gap lower than 3.0 eV confirming the absorption shift to visible-light region. The formation of •OH radicals and methylene blue dye degradation increases as the g-C3N4 doping percent also increases, following the trend ΤiO2 < GNT1% ≈ GNT2.5% < GNT5%. A z-scheme mechanism is attributed to the photocatalytic performance confirming the potential for green chemistry and environmental technology applications.
      Citation: Catalysts
      PubDate: 2019-10-24
      DOI: 10.3390/catal9110880
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 881: Decreasing COD in Sugarcane Vinasse Using
           the Fenton Reaction: The Effect of Processing Parameters

    • Authors: Dhias Cahya Hakika, Sarto Sarto, Aswati Mindaryani, Muslikhin Hidayat
      First page: 881
      Abstract: An experiment on Fenton degradation of sugarcane vinasse was carried out to determine its effect on the wastewater characteristics. Vinasse, a by-product of distillation in the bioethanol industry, contains high organic matter, as the value of chemical oxygen demand (COD) is >100,000 mg/L and BOD5 is 31,250 mg/L. The Fenton reaction is one of the advanced oxidation process (AOP) methods which has been widely applied for the treatment of wastewater containing organic pollutants and contaminants. This method utilizes hydroxyl radical (•OH) produced from the catalyzing reaction between Fe2+ or Fe3+ and hydrogen peroxide. The effect of pH, the ratio of [H2O2] and [COD], and the ratio of [H2O2] to [Fe3+] were studied in this research to evaluate the Fenton reaction. Results from this experiment showed that treatment of vinasse using the Fenton reaction decreased the COD value to 48.10%, and its biodegradability enhanced almost two times at a pH value of 3.8, a ratio of [H2O2] to [COD] of 0.62, and a ratio of [H2O2] to [Fe3+] of 50 (g/g), which demonstrated that the Fenton treatment was effective to reduce organic matter of sugarcane vinasse. Three kinetic models (first order, second order, and Behnajad–Modirshahla–Ghanbery (BMG) kinetic model) were used to evaluate the degradation of the COD value. On the basis of the value of R2 (coefficient of determination), we suggested that BMG represented the best kinetic model. This study finds that the Fenton treatment is able to mitigate the environmental impacts of sugarcane vinasse.
      Citation: Catalysts
      PubDate: 2019-10-24
      DOI: 10.3390/catal9110881
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 882: Ion Exchange of One-Pot Synthesized
           Cu-SAPO-44 with NH4NO3 to Promote Cu Dispersion and Activity for Selective
           Catalytic Reduction of NOx with NH3

    • Authors: Nana Zhang, Ying Xin, Qian Li, Xicheng Ma, Yongxin Qi, Lirong Zheng, Zhaoliang Zhang
      First page: 882
      Abstract: Cu-containing CHA type (Cu-CHA) zeolites have been widely investigated owing to their excellent low-temperature activity and high hydrothermal stability in selective catalytic reduction of NOx with NH3 (NH3-SCR). Herein, a series of Cu-SAPO-44 zeolites were prepared by one-pot method with dual-amine templates and the subsequent ion exchange (IE) with NH4NO3. The effect of NH4NO3 treatment on Cu species was investigated by X-ray powder diffraction (XRD), N2 adsorption-desorption isotherm, inductively coupled plasma (ICP); field-emission scanning electron microscope (FE-SEM), high-resolution transmission electron microscope (HRTEM), X-ray absorption fine structure (XAFS), and H2-temperature-programmed reduction (H2-TPR). The results indicated that—besides the main SAPO-44 structure—the CuO phase was detected by XRD in original samples. After IE with NH4NO3, the Cu contents decreased greatly from ICP analysis. The removal of CuO agglomerations and the presence of highly dispersed CuO nanoparticles (~2.36 nm) were confirmed by SEM, TEM and H2-TPR. Furthermore, a significant increase in the proportion of isolated Cu2+ was derived from XAFS. As a result, the activity at higher temperature (≥350 °C) was improved a lot.
      Citation: Catalysts
      PubDate: 2019-10-24
      DOI: 10.3390/catal9110882
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 883: Bioproduction of Isoprenoids and Other
           Secondary Metabolites Using Methanotrophic Bacteria as an Alternative
           Microbial Cell Factory Option: Current Stage and Future Aspects

    • Authors: Young Chan Jeon, Anh Duc Nguyen, Eun Yeol Lee
      First page: 883
      Abstract: Methane is a promising carbon feedstock for industrial biomanufacturing because of its low price and high abundance. Recent advances in metabolic engineering and systems biology in methanotrophs have made it possible to produce a variety of value-added compounds from methane, including secondary metabolites. Isoprenoids are one of the largest family of secondary metabolites and have many useful industrial applications. In this review, we highlight the current efforts invested to methanotrophs for the production of isoprenoids and other secondary metabolites, including riboflavin and ectoine. The future outlook for improving secondary metabolites production (especially of isoprenoids) using metabolic engineering of methanotrophs is also discussed.
      Citation: Catalysts
      PubDate: 2019-10-24
      DOI: 10.3390/catal9110883
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 884: Catalyzed Synthesis of Natural Products

    • Authors: David Diez
      First page: 884
      Abstract: Natural Products are secondary metabolites, that have been the inspiration for chemists and chemical biologists for many years and have a special relevance in the chemical space [...]
      Citation: Catalysts
      PubDate: 2019-10-25
      DOI: 10.3390/catal9110884
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 885: Selective Catalytic Transfer Hydrogenolysis
           of Glycerol to 2-Isopropoxy-Propan-1-Ol over Noble Metal Ion-Exchanged
           Mordenite Zeolite

    • Authors: Bhupendra Kumar Singh, Yongseok Kim, Seungdon Kwon, Kyungsu Na
      First page: 885
      Abstract: This study investigated the selective conversion of glycerol to 2-isopropoxy-propan-1-ol over noble metal ion-exchanged mordenite zeolites (RuMOR, RhMOR, and PdMOR) as heterogeneous catalysts via catalytic transfer hydrogenolysis (CTH) using propan-2-ol as the solvent, hydrogen supplier, and reactive coupling reagent with glycerol. The catalytic reactions were performed at 140 °C under inert conditions with a 0.5 MPa initial pressure of N2. A single product, 2-isopropoxy-propan-1-ol, was catalytically generated without any appreciable by-products. The catalytic results were reproducible, and the catalysts exhibited good recyclability.
      Citation: Catalysts
      PubDate: 2019-10-25
      DOI: 10.3390/catal9110885
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 886: Synthesis of Diesel and Jet Fuel Range
           Cycloalkanes with Cyclopentanone and Furfural

    • Authors: Wei Wang, Shaoying Sun, Fengan Han, Guangyi Li, Xianzhao Shao, Ning Li
      First page: 886
      Abstract: Diesel and jet fuel range cycloalkanes were obtained in ~84.8% overall carbon yield with cyclopentanone and furfural, which can be produced from hemicellulose. Firstly, 2,5-bis(furan-2-ylmethyl)-cyclopentanone was prepared by the aldol condensation/hydrogenation reaction of cyclopentanone and furfural under solid base and selective hydrogenation catalyst. Over the optimized catalyst (Pd/C-CaO), 98.5% carbon yield of 2,5-bis(furan-2-ylmethyl)-cyclopentanone was acquired at 423 K. Subsequently, the 2,5-bis(furan-2-ylmethyl)-cyclopentanone was further hydrodeoxygenated over the M/H-ZSM-5(Pd, Pt and Ru) catalyst. Overall, 86.1% carbon yield of diesel and jet fuel range cycloalkanes was gained over the Pd/H-ZSM-5 catalyst under solvent-free conditions. The cycloalkane mixture obtained in this work has a high density (0.82 g mL−1) and a low freezing point (241.7 K). Therefore, it can be mixed into diesel and jet fuel to increase their volumetric heat values or payloads.
      Citation: Catalysts
      PubDate: 2019-10-25
      DOI: 10.3390/catal9110886
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 887: A DFT Study of Acetylene Hydrogenation
           Catalyzed by S-Doped Pd1/g-C3N4

    • Authors: Lihua Kang, Mingyuan Zhu, Yu Zhao
      First page: 887
      Abstract: To exploit the excellent properties of g-C3N4, more and more studies have been carried out in various fields in recent years to improve the selectivity of catalysts, especially for selective acetylene hydrogenation. To our best knowledge, Pd catalyst is of great importance to hydrogenate acetylene in ethylene feed. Though we have explored the hydrogenation of acetylene catalyzed by Pd1/g-C3N4 before, doping with non-metals has never been studied. In this work, the mechanisms of selective hydrogenation of acetylene to ethylene on S-doped Pd1/g-C3N4 were investigated and we also compared this result with undoped Pd1/g-C3N4. By comparing the activation energy and selectivity of undoped Pd1/g-C3N4 with those of S-doped C and N sites of Pd1/g-C3N4, we found that S-doped C sites can improve the reactivity, but with a poor selectivity, while the activity of S atom doped N sites was not improved, but the selectivity has improved. Our work provides significant insights to explore the development of high efficiency non-metallic doping single metal atoms supported on 2D layered materials.
      Citation: Catalysts
      PubDate: 2019-10-25
      DOI: 10.3390/catal9110887
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 888: Facile Fabrication of Metal Oxide Based
           Catalytic Electrodes by AC Plasma Deposition and Electrochemical Detection
           of Hydrogen Peroxide

    • Authors: Quang-Tan Bui, In-Keun Yu, Anantha Iyengar Gopalan, Gopalan Saianand, Woonjung Kim, Seong-Ho Choi
      First page: 888
      Abstract: In this study, the fabrication of a metal oxide nanoparticles (NPs) dispersed catalytic electrode is described based on a new alternating current (AC) plasma deposition approach. The fabrication involves the treatment of AC plasma on a precursor solution comprised of metal salts such as CuCl2, FeCl2, and ZnCl2, and a monomer (acrylic acid) in the presence/absence of a cross-linker. Furthermore, the utility of such developed electrodes has been demonstrated for the electrochemical determination of hydrogen peroxide (H2O2). The electrode materials obtained through plasma treatment was characterized by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscope (SEM), contact angle measurements, energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and cyclic voltammetry. Among the metal oxide modified electrodes prepared by the AC plasma deposition method, the copper oxide (CuO) NPs catalytic electrode exhibited significant oxidation and reduction peaks for H2O2 in phosphate-buffered saline solution. The catalytic electrode with CuO NPs exhibited a combination of good H2O2 sensing characteristics such as good sensitivity (63.52 mA M−1 cm−2), good selectivity, low detection limits (0.6 µM), fast sensing response (5 s), a wide linear range (0.5–8.5 mM), and good stability over 120 cycles. Based on our results, it is well demonstrated that plasma deposition could be effectively utilized for the fabrication of the catalytic electrode for detection of H2O2 concentrations. Further, the strategy of using AC plasma for fabrication of metal oxide-based modified electrodes could also be extended for the fabrication of other kinds of nanomaterials-based sensors.
      Citation: Catalysts
      PubDate: 2019-10-25
      DOI: 10.3390/catal9110888
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 889: Effect of Surface Composition and Structure
           of the Mesoporous Ni/KIT-6 Catalyst on Catalytic Hydrodeoxygenation
           Performance

    • Authors: Xianming Zhang, Shuang Chen, Fengjiao Wang, Lidan Deng, Jianmin Ren, Zhaojie Jiao, Guilin Zhou
      First page: 889
      Abstract: A series of Ni/KIT6 catalyst precursors with 25 wt.% Ni loading amount were reduced in H2 at 400, 450, 500, and 550 °C, respectively. The studied catalysts were investigated by XRD, Quasi in-situ XPS, BET, TEM, and H2-TPD/Ranalysis methods. It was found that reduction temperature is an important factor affecting the hydrodeoxygenation (HDO) performance of the studied catalysts because of the Strong Metal Support Interaction Effect (SMSI). The reduction temperature influences mainly the content of active components, crystal size, and the abilityfor adsorbing and activating H2. The developed pore structure and large specific surface area of the KIT-6 support favored the Ni dispersion. The RT450 catalyst, which was prepared in H2 atmosphere at 450 °C, has the best HDO performance. Ethyl acetate can be completely transformed and maintain 96.8% ethane selectivity and 3.2% methane selectivity at 300 °C. The calculated apparent activation energies of the prepared catalysts increased in the following order: RT550 > RT400 > RT500 > RT450.
      Citation: Catalysts
      PubDate: 2019-10-25
      DOI: 10.3390/catal9110889
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 890: Chiral N-heterocyclic Carbene Gold
           Complexes: Synthesis and Applications in Catalysis

    • Authors: Michalak, Kośnik
      First page: 890
      Abstract: N-Heterocyclic carbenes have found many applications in modern metal catalysis, due to the formation of stable metal complexes, and organocatalysis. Among a myriad of N-heterocyclic carbene metal complexes, gold complexes have gained a lot of attention due to their unique propensity for the activation of carbon-carbon multiple bonds, allowing many useful transformations of alkynes, allenes, and alkenes, inaccessible by other metal complexes. The present review summarizes synthetic efforts towards the preparation of chiral N-heterocyclic gold(I) complexes exhibiting C2 and C1 symmetry, as well as their applications in enantioselective catalysis. Finally, the emerging area of rare gold(III) complexes and their preliminary usage in asymmetric catalysis is also presented.
      Citation: Catalysts
      PubDate: 2019-10-25
      DOI: 10.3390/catal9110890
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 891: Heterogeneous Oxidation of Phenolic
           Compounds with Photosensitizing Catalysts Incorporated into Chitosan

    • Authors: Foszpańczyk, Bilińska, Gmurek, Ledakowicz
      First page: 891
      Abstract: The increasing amount of hazardous micropollutants in the aqueous environment has recently become a concern, especially because they are not usually included in environmental monitoring programs. There is also limited knowledge regarding their behavior in the environment and their toxicity. This paper presents results regarding the heterogeneous photosensitized oxidation of 10 phenolic compounds under visible light. All of the selected compounds are classified as pollutants of emerging concern. For the first time, the application of photosensitizing catalysts incorporated into a chitosan carrier was investigated from several points of view, namely, structure characterization, singlet oxygen generation potential, photodegradation ability, biodegradability, and toxicity assessment. It was found that compounds of different origins were degraded with high effectivity. Photoactive chitosan was stable and could be reused for at least 12 cycles without losing its photocatalytic activity. The Hammett constants for all of the degraded compounds were determined. Improved biodegradability after the treatment was achieved for almost all compounds, apart from 4-hydroxybenzoic acid, and only slightly for 2-phenylphenol. The acute toxicity was assessed using bioluminescent Vibrio fischeri bacteria, indicating lower toxicity than the parent compounds.
      Citation: Catalysts
      PubDate: 2019-10-25
      DOI: 10.3390/catal9110891
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 892: Surface Modification of a MOF-based Catalyst
           with Lewis Metal Salts for Improved Catalytic Activity in the Fixation of
           CO2 into Polymers

    • Authors: Sudakar Padmanaban, Sungho Yoon
      First page: 892
      Abstract: The catalyst zinc glutarate (ZnGA) is widely used in the industry for the alternating copolymerization of CO2 with epoxides. However, the activity of this heterogeneous catalyst is restricted to the outer surface of its particles. Consequently, in the current study, to increase the number of active surface metal centers, ZnGA was treated with diverse metal salts to form heterogeneous, surface-modified ZnGA-Metal chloride (ZnGA-M) composite catalysts. These catalysts were found to be highly active for the copolymerization of CO2 and propylene oxide. Among the different metal salts, the catalysts treated with ZnCl2 (ZnGA-Zn) and FeCl3 (ZnGA-Fe) exhibited ~38% and ~25% increased productivities, respectively, compared to untreated ZnGA catalysts. In addition, these surface-modified catalysts are capable of producing high-molecular-weight polymers; thus, this simple and industrially viable surface modification method is beneficial from an environmental and industrial perspective.
      Citation: Catalysts
      PubDate: 2019-10-26
      DOI: 10.3390/catal9110892
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 893: Catalytic Oxidation Processes for the
           Upgrading of Terpenes: State-of-the-Art and Future Trends

    • Authors: Denicourt-Nowicki, Rauchdi, Ali, Roucoux
      First page: 893
      Abstract: Terpenic olefins constitute a relevant platform of renewable molecules, which could be used as key intermediates for the perfumery, flavoring, and pharmaceutical industries. The upgrading of these cheap and available agro-resources through catalytic oxidation processes remains of great interest, leading to the formation of either epoxides via the oxidation of the olefinic bond or α,β-unsaturated ketones by the Csp3-H functionalization at the α-position of the double bond. This critical review summarizes some of the most relevant homogeneous or heterogeneous catalysts designed for the oxidation of some abundant terpenic olefins in the last decade (2008–2018).
      Citation: Catalysts
      PubDate: 2019-10-27
      DOI: 10.3390/catal9110893
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 894: Performance of Catalysts of Different Nature
           in Model Tar Component Decomposition

    • Authors: Pavol Steltenpohl, Jakub Husár, Patrik Šuhaj, Juma Haydary
      First page: 894
      Abstract: Municipal solid waste constitutes one of the major challenges and concerns of our society. Disposal of waste material is potentially dangerous, harming both environment and mankind. In order to diminish negative effects of municipal solid waste, its thermal decomposition to valuable chemicals has been studied. The principal draw-back of thermal processes used for solid waste utilization as raw material is tar formation. In this study, low-cost catalysts of different origin were tested in the decomposition of a model component of tar originating from waste material pyrolysis/gasification. p-Xylene was selected as the model compound found in biomass decomposition products. Its decomposition was carried out in the presence of either tire pyrolysis char- or clay minerals-based catalysts. Tar-cracking activities of both catalyst types at varying experimental conditions were compared and related to the catalysts physical-chemical properties. In experiments, either empty reactor or reactor filled with 10 g of the catalyst was used; p-xylene mass flow was set to 2.58 g h−1 (50 μL min−1, room temperature), and decomposition temperature ranging from 750 °C to 850 °C was applied. Moreover, evolution of the output variables, p-xylene conversion and hydrogen content in the gas phase, with the reaction time was investigated. Catalysts’ properties were assessed based on nitrogen adsorption isotherms, thermogravimetric and elemental composition analyses. Amounts and composition of p-xylene catalytic decomposition products were evaluated using GC analysis of both gaseous phase and condensable products. Results showed the superiority of tire pyrolysis char catalyst over that based on clay minerals.
      Citation: Catalysts
      PubDate: 2019-10-27
      DOI: 10.3390/catal9110894
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 895: Tandem Hydrogenation/Hydrogenolysis of
           Furfural to 2-Methylfuran over a Fe/Mg/O Catalyst: Structure–Activity
           Relationship

    • Authors: Carlo Lucarelli, Danilo Bonincontro, Yu Zhang, Lorenzo Grazia, Marc Renom-Carrasco, Chloé Thieuleux, Elsje Alessandra Quadrelli, Nikolaos Dimitratos, Fabrizio Cavani, Stefania Albonetti
      First page: 895
      Abstract: The hydrodeoxygenation of furfural (FU) was investigated over Fe-containing MgO catalysts, on a continuous gas flow reactor, using methanol as a hydrogen donor. Catalysts were prepared either by coprecipitation or impregnation methods, with different Fe/Mg atomic ratios. The main product was 2-methylfuran (MFU), an important highly added value chemical, up to 92% selectivity. The catalyst design helped our understanding of the impact of acid/base properties and the nature of iron species in terms of catalytic performance. In particular, the addition of iron on the surface of the basic oxide led to (i) the increase of Lewis acid sites, (ii) the increase of the dehydrogenation capacity of the presented catalytic system, and (iii) to the significant enhancement of the FU conversion to MFU. FTIR studies, using methanol as the chosen probe molecule, indicated that, at the low temperature regime, the process follows the typical hydrogen transfer reduction, but at the high temperature regime, methanol dehydrogenation and methanol disproportionation were both presented, whereas iron oxide promoted methanol transfer. FTIR studies were performed using furfural and furfuryl alcohol as probe molecules. These studies indicated that furfuryl alcohol activation is the rate-determining step for methyl furan formation. Our experimental results clearly demonstrate that the nature of iron oxide is critical in the efficient hydrodeoxygenation of furfural to methyl furan and provides insights toward the rational design of catalysts toward C–O bonds’ hydrodeoxygenation in the production of fuel components.
      Citation: Catalysts
      PubDate: 2019-10-27
      DOI: 10.3390/catal9110895
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 896: Deciphering the Effect of Microbead Size
           Distribution on the Kinetics of Heterogeneous Biocatalysts through
           Single-Particle Analysis Based on Fluorescence Microscopy

    • Authors: Emilio Muñoz-Morales, Susana Velasco-Lozano, Ana I. Benítez-Mateos, María J. Marín, Pedro Ramos-Cabrer, Fernando López-Gallego
      First page: 896
      Abstract: Understanding the functionality of immobilized enzymes with spatiotemporal resolution and under operando conditions is an unmet need in applied biocatalysis, as well as priceless information to guide the optimization of heterogeneous biocatalysts for industrial purposes. Unfortunately, enzyme immobilization still relies on trial-and-error approximations that prevail over rational designs. Hence, a modern fabrication process to achieve efficient and robust heterogeneous biocatalysts demands comprehensive characterization techniques to track and understand the immobilization process at the protein–material interface. Recently, our group has developed a new generation of self-sufficient heterogeneous biocatalysts based on alcohol dehydrogenases co-immobilized with nicotinamide cofactors on agarose porous microbeads. Harnessing the autofluorescence of NAD+(P)H and using time-lapse fluorescence microscopy, enzyme activity toward the redox cofactors can be monitored inside the beads. To analyze these data, herein we present an image analytical tool to quantify the apparent Michaelis–Menten parameters of alcohol dehydrogenases co-immobilized with NAD(P)+/H at the single-particle level. Using this tool, we found a strong negative correlation between the apparent catalytic performance of the immobilized enzymes and the bead radius when using exogenous bulky substrates in reduction reactions. Therefore, applying image analytics routines to microscopy studies, we can directly unravel the functional heterogeneity of different heterogeneous biocatalyst samples tested under different reaction conditions.
      Citation: Catalysts
      PubDate: 2019-10-28
      DOI: 10.3390/catal9110896
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 897: Tailoring Celluclast® Cocktail’s
           Performance towards the Production of Prebiotic Cello-Oligosaccharides
           from Waste Forest Biomass

    • Authors: Anthi Karnaouri, Leonidas Matsakas, Saskja Bühler, Madhu Nair Muraleedharan, Paul Christakopoulos, Ulrika Rova
      First page: 897
      Abstract: The main objective of this study focused on the sustainable production of cellobiose and other cellulose-derived oligosaccharides from non-edible sources, more specifically, from forest residues. For this purpose, a fine-tuning of the performance of the commercially available enzyme mixture Celluclast® was conducted towards the optimization of cellobiose production. By enzyme reaction engineering (pH, multi-stage hydrolysis with buffer exchange, addition of β-glucosidase inhibitor), a cellobiose-rich product with a high cellobiose to glucose ratio (37.4) was achieved by utilizing organosolv-pretreated birch biomass. In this way, controlled enzymatic hydrolysis combined with efficient downstream processing, including product recovery and purification through ultrafiltration and nanofiltration, can potentially support the sustainable production of food-grade oligosaccharides from forest biomass. The potential of the hydrolysis product to support the growth of two Lactobacilli probiotic strains as a sole carbon source was also demonstrated.
      Citation: Catalysts
      PubDate: 2019-10-28
      DOI: 10.3390/catal9110897
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 898: Positive Effects of Impregnation of Fe-oxide
           in Mesoporous Al-Oxides on the Decontamination of Dimethyl
           Methylphosphonate

    • Authors: Tae Gyun Woo, Byeong Jun Cha, Young Dok Kim, Hyun Ook Seo
      First page: 898
      Abstract: Dimethyl methylphosphonate (DMMP) is an important simulant of organophosphates pesticides and chemical warfare nerve agents. Here, we investigated the catalytic decontamination of DMMP on Fe-oxide impregnated mesoporous Al2O3. Fe-oxide/Al2O3 sample was prepared via the temperature regulated chemical vapor deposition of Fe-oxide on mesoporous Al2O3 and post-annealing at 750 °C. The Fe-oxide/Al2O3 and bare Al2O3 samples were exposed to DMMP-containing dry air at room temperature to study the effects of Fe-oxide impregnation on the reactive adsorption of DMMP. The facilitation of DMMP degradation into CO2 and methanol at room temperature in the presence of nano-dispersed Fe-oxide was evidenced by gas-chromatograph and Fourier transform-infrared (FT-IR) absorption spectroscopy. In addition, temperature programmed oxidation (TPO) experiments and gas chromatography (Agilent, 6890) equipped with mass spectrometer (Agilent, 5973N) (GC/MS) analyses revealed that the minimum temperature that was required for total oxidation of DMMP into CO2 can also be lowered by Fe-oxide impregnation in mesoporous Al2O3.
      Citation: Catalysts
      PubDate: 2019-10-28
      DOI: 10.3390/catal9110898
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 899: Effects of Additives and Metals on
           Crystallization of Nano-Sized HZSM-5 Zeolite for Glycerol Aromatization

    • Authors: Wei Xu, Lijing Gao, Guomin Xiao
      First page: 899
      Abstract: Nano-sized HZSM-5 (n-HZSM-5) was synthesized and applied in the aromatization of glycerol. The effects of additives (carboxymethylcellulose sodium, NaCl, sodium alginate, etc.) on the chemical and physic properties of n-HZSM-5 during preparation were investigated. Metal modification was also investigated based on the synthesized n-HZSM-5. The results showed that the addition of carboxymethylcellulose sodium (CMC-Na), NaCl and sodium alginate (SA) led to forming smaller sizes of HZSM-5 and promoted the acid amounts of the catalysts, which increased its catalytic activities for obtaining BTX. The highest BTX yield of ~35% was obtained by SA derived n-HZSM-5, and the life of the catalyst were both obviously promoted by the additives with a highest of ~11 h by γ-(2,3-epoxypropoxy)propytrimethoxysilane (KH-560) derived n-HZSM-5. BTX yields could be improved by 40%by the addition of Zn and Cd in n-HZSM-5 while having little effect on the catalyst life.
      Citation: Catalysts
      PubDate: 2019-10-28
      DOI: 10.3390/catal9110899
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 900: Effect of Shale Ash-Based Catalyst on the
           Pyrolysis of Fushun Oil Shale

    • Authors: Hao Lu, Fengrui Jia, Chuang Guo, Haodan Pan, Xu Long, Guangxin Liu
      First page: 900
      Abstract: The effect of shale ash (SA)-based catalysts (SA as carriers to support several transition metal salts, such as ZnCl2, NiCl2·6H2O, and CuCl2·2H2O) on oil shale (OS) pyrolysis was studied. Results showed that SA promoted OS pyrolysis, and the optimum weight ratio of OS:SA was found to be 2:1. The SA-supported transition metal salt catalyst promoted the OS pyrolysis, and the catalytic effect increased with increasing load of the transition metal salt within 0.1–3.0 wt%. The transition metal salts loaded on the SA not only promoted OS pyrolysis and reduced the activation energy required but also changed the yield of pyrolysis products (reduced shale oil and semi-coke yields and increased gas and loss yield). SA-supported 3 wt% CuCl2·2H2O catalyst not only exhibited the highest ability to reduce the activation energy in OS pyrolysis (32.84 kJ/mol) but also improved the gas and loss yield, which was 4.4% higher than the uncatalyzed reaction. The supporting transition metal salts on the SA also increased the content of short-chain hydrocarbons in aliphatic hydrocarbons in shale oil and catalyzed the aromatization of aliphatic hydrocarbons to form aromatic hydrocarbons. The catalytic activity of the transition metal salt on the SA-based catalyst for OS pyrolysis decreased in the order of CuCl2·2H2O > NiCl2·6H2O > ZnCl2.
      Citation: Catalysts
      PubDate: 2019-10-28
      DOI: 10.3390/catal9110900
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 901: The Use of a γ-Al2O3 and MgO Mixture in the
           Catalytic Conversion of 1,1,1,2-Tetrafluoroethane (HFC-134a)

    • Authors: Sangjae Jeong, Gamal Luckman Sudibya, Jong-Ki Jeon, Young-Min Kim, Caroline Mercy Andrew Swamidoss, Seungdo Kim
      First page: 901
      Abstract: This paper reports the improved efficiency of 1,1,1,2-tetrafluoroethane (HFC-134a) decomposition by combined use of MgO with γ-Al2O3. While a high temperature (>900 °C) was required to achieve 90% conversion during non-catalytic pyrolysis of HFC-134a, 100% conversion of HFC-134a was achieved at 600 °C by the use of γ-Al2O3. Among the three catalysts (γ-Al2O3, MgO, and CaO) tested in this study, γ-Al2O3 showed the highest HFC-134a decomposition efficiency, followed by MgO and CaO, due to its large surface area and large amount of weak acid sites. Also with the longest lifetime among the catalysts, durability in maintaining complete decomposition of HFC-134a was shown in γ-Al2O3. The addition of MgO to γ-Al2O3 was effective in extending the lifetime of γ-Al2O3 due to the efficient interaction between HF and MgO, which can delay the deactivation of γ-Al2O3. Compared to the double bed γ-Al2O3-MgO configuration, the use of a mixed γ-Al2O3-MgO bed extended the catalyst lifetime more effectively.
      Citation: Catalysts
      PubDate: 2019-10-28
      DOI: 10.3390/catal9110901
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 902: Y-Modified MCM-22 Supported PdOx Nanocrystal
           Catalysts for Catalytic Oxidation of Toluene

    • Authors: Zhu Chen, Danna Situ, Jie Zheng, Zhen Cheng, Zhuo Wang, Shufeng Zuo
      First page: 902
      Abstract: A series of rare earth elements (REEs)-modified and Mobil Composition of Matter (MCM)-22-supported Pd nanocrystal catalysts were synthesized via a high-temperature solution-phase reduction method and tested for toluene complete oxidation. These catalytic materials were systematically characterized by N2 adsorption/desorption, X-ray powder diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), energy-dispersive spectroscopy (EDS), inductively coupled plasma atomic emission spectroscopy (ICP-AES), temperature-programmed surface reaction of toluene (toluene-TPSR) and X-ray photoelectron spectroscopic (XPS) techniques in order to investigate the structure–catalytic property relationship. Moreover, catalysts with an appropriate yttrium content greatly improved the catalytic activity of 0.2%Pd/MCM-22. PdOx (x = 0, 1) nanoparticles, ranging from 3.6 to 6.8 nm, which were well distributed on the surface of MCM-22. Efficient electron transfer from the Pd2+/Pd0 redox cycle facilitated the catalytic oxidation process, and the formation of Pd (or Y) –O–Si bonds improved the high dispersion of the PdOx and Y2O3 particles. Toluene–TPSR experiments suggested that the addition of Y2O3 improved the physical/chemical adsorption of 0.2%Pd/MCM-22, thus increasing the toluene adsorption capacity. Then, 0.2%Pd/7.5%Y/MCM-22 exhibited the highest catalytic performance. In addition, this catalyst maintained 95% conversion with high resistance to water and chlorine poisoning, even after toluene oxidation at 210 °C for 100 h, making it more valuable in practical applications.
      Citation: Catalysts
      PubDate: 2019-10-28
      DOI: 10.3390/catal9110902
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 903: Peptide–Gold Nanoparticle Conjugates as
           Artificial Carbonic Anhydrase Mimics

    • Authors: Dorian J. Mikolajczak, Beate Koksch
      First page: 903
      Abstract: We herein describe the design and synthesis of a catalytically active peptide–gold nanoparticle conjugate (Pep-Au-NP) that binds Zn(II) within its peptide monolayer and develops carbonic anhydrase activity. Specifically, a modified variant of the β-sheet forming IHIHIQI-peptide (IHQ), which forms an interstrand 3-His Zn(II)-binding site, was used as a ligand for spherical gold nanoparticles (Au-NPs). The resulting immobilized peptide maintains its ability to form β-sheets, as determined by circular dichroism (CD)-spectroscopy and, thus, maintains its ability to form Zn(II)-binding sites. The addition of Zn(II)-ions to the peptide–gold nanoparticle conjugates (Au@IHQ-NP) resulted in significant improvements in rates of ester hydrolysis of 4-nitrophenyl acetate (4-NPA) and the hydration of CO2 compared to the unconjugated peptide variants. Recycling of the catalyst revealed that Au@IHQ-NP remains intact with at least 94% of its initial activity after five rounds of CO2 hydration. The herein reported results reveal that Pep-Au-NPs are able to perform reactions catalyzed by natural metalloenzymes and open up new possibilities for the implementation of these conjugates.
      Citation: Catalysts
      PubDate: 2019-10-29
      DOI: 10.3390/catal9110903
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 904: Enhanced Selective Production of Arenes and
           Regenerating Rate in Aryl Ether Hydrogenolysis over Mesoporous Nickel in
           Plug-Flow Reactors

    • Authors: Chunming Zheng, Dongxue Wang, Xudong Hu, Chao Ma, Xuan Liu, Ying Wang, Yinkui Yu, Jiaqi Wang, Xiaohong Sun
      First page: 904
      Abstract: Ordered mesoporous nickel (mesoNi) was successfully synthesized with a hard templating method by using KIT-6 ordered mesoporous silica as a template. With small-angle X-ray diffraction (SAXRD), transmission electron microscopy (TEM) and N2 sorption technique, the mesoporous structures of synthesized catalysts were characterized with desired high surface area (84.2 m2·g−1) and narrow pore size distribution. MesoNi exhibited outstanding catalytic cleavage activity for lignin model compounds (benzyl phenyl ether, BPE) with high selectivity of arenes in the flow reactor system. MesoNi also showed higher regeneration rates than non-porous ones, which were confirmed from deactivation and regeneration mechanism studies in the flow reaction system with varied high temperature and pressure. The adsorbed poisoning species on the mesoporous Ni surface were analyzed and phenol could be the main poisoning species. The excellent catalytic cleavage performance of mesoNi originates from their unique mesoporous structure, which offers high surface area and Ni active sites. The outstanding catalytic performance shows that this process provides a promising candidate for improved lignin valorization with general applicability.
      Citation: Catalysts
      PubDate: 2019-10-29
      DOI: 10.3390/catal9110904
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 905: Role of the Outer Metal of Double Metal
           Cyanides on the Catalytic Efficiency in Styrene Oxidation

    • Authors: Paulina Molina-Maldonado, Rosario Ruíz-Guerrero, Carlos Hernández-Fuentes
      First page: 905
      Abstract: The catalytic efficiency of double metal cyanide (DMC) has been shown to be very effective in heterogeneous catalysis. The catalytic activity of the outer divalent cations (Mn, Co, Ni, and Cu) of a family of hexacyanocobaltates was examined in the oxidation reaction of styrene, as a model molecule, using tert Butyl Hydroperoxide (TBHP, Luperox®) as an oxidizing agent. The most electronegative outer cations showed the best conversions, with 95% for copper, followed by nickel with 85% conversion of the monomer at atmospheric pressure and temperature of 75 °C. The evidence showed that the catalytic activity and selectivity towards oxidized products are strongly linked to the accurate choice of the outer cation in the DMC together with the oxidizing agent.
      Citation: Catalysts
      PubDate: 2019-10-29
      DOI: 10.3390/catal9110905
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 906: Acceleration of Persulfate Activation by
           MIL-101(Fe) with Vacuum Thermal Activation: Effect of FeII/FeIII
           Mixed-Valence Center

    • Authors: Jieyang Yang, Zequan Zeng, Zhanggen Huang, Yan Cui
      First page: 906
      Abstract: In this work, the activation effect of vacuum thermal treatment on MIL-101(Fe) (MIL: Materials of Institute Lavoisier) was investigated for the first time. It demonstrated that vacuum thermal activation could accelerate the activation of persulfate (PS) by MIL-101(Fe), and the enhancement of the catalytic capacity of MIL-101(Fe) was mainly attributed to the change in the FeII/FeIII mixed-valence center. The results of the SEM and XRD showed that vacuum thermal activation had a negligible effect on the crystal structure and particle morphology of MIL-101(Fe). Meanwhile, the higher temperature of vacuum thermal activation caused a higher relative content ratio of FeII/FeIII. A widely used azo dye, X-3B, was chosen as the probe molecule to investigate the catalytic performance of all samples. The results showed that the activated samples could remove X-3B more effectively, and the sample activated at 150 °C without regeneration could effectively activate PS to remove X-3B for at least 5 runs and approximately 900 min. This work highlights the often-overlooked activation effect of vacuum thermal treatment and provides a simple way to improve the catalytic capacity and reusability of MIL-101(Fe) which is beneficial for the application of MIL-101(Fe)/PS systems in azo dye wastewater treatment.
      Citation: Catalysts
      PubDate: 2019-10-29
      DOI: 10.3390/catal9110906
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 907: Rational Design of Metal Oxide Solid Acids
           for Sugar Conversion

    • Authors: Takagaki
      First page: 907
      Abstract: Aqueous-phase acid-catalyzed reactions are essential for the conversion of cellulose-based biomass into chemicals. Brønsted acid and Lewis acid play important roles for these reactions, including hydrolysis of saccharides, isomerization and epimerization of aldoses, conversion of d-glucose into 5-hydroxymethylfurfural, cyclodehydration of sugar alcohols and conversion of trioses into lactic acid. A variety of metal oxide solid acids has been developed and applied for the conversion of sugars so far. The catalytic activity is mainly dependent on the structures and types of solid acids. Amorphous metal oxides possess coordinatively unsaturated metal sites that function as Lewis acid sites while some crystal metal oxides have strong Brønsted acid sites. This review introduces several types of metal oxide solid acids, such as layered metal oxides, metal oxide nanosheet aggregates, mesoporous metal oxides, amorphous metal oxides and supported metal oxides for sugar conversions.
      Citation: Catalysts
      PubDate: 2019-10-29
      DOI: 10.3390/catal9110907
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 908: Facile Green Preparation of Rhodium
           Nanoclusters Supported Nano-Scaled Graphene Platelets for Sonogashira
           Coupling Reaction and Reduction of p-Nitrophenol

    • Authors: Gopiraman Mayakrishnan, Saravanamoorthy Somasundaram, Sana Ullah, Ilangovan Andivelu, Kim Ick Soo, Chung Ill Min
      First page: 908
      Abstract: Rhodium nanoclusters were uniformly dispersed on nano-scaled graphene platelets by a simple ‘mix and heat’ method without using any toxic reagents. Distilled water was used to obtain the homogenous dispersion of Rh-nanoclusters on graphene platelets. The morphology of the resultant catalyst (Rh(0)NCs/GNPs) was studied by means of transmission electron microscope (TEM) and atomic force microscope (AFM) analyses. The X-ray photoemission spectroscope (XPS) result confirmed the metallic form of Rh-nanoclusters in Rh(0)NCs/GNPs. The crystalline property and the interaction between Rh-nanoclusters and graphene platelets (GNPs) were studied by means of XRD and Raman analysis. The Rh-loading in Rh(0)NCs/GNPs was confirmed by scanning electron microscope and energy dispersive spectroscope (SEM-EDS) and inductively coupled plasma-mass spectroscope (ICP-MS) analysis. After being optimized, the Rh(0)NCs/GNPs used as catalyst for the reduction of 4-nitrophenol with NaBH4 and the Sonogashira coupling reaction between iodobenzene with phenylacetylene. To our delight, the Rh(0)NCs/GNPs showed excellent catalytic activity towards the reduction of 4-nitrophenol with an excellent turnover frequency (TOF) value of 112.5 min−1. The kapp and k’ values were calculated to be 62.07 × 10−3 min−1(0.002 mg of Rh(0)NCs/GNPs) and 31035 × 10−3 mg−1 min−1,respectively. Alike, under the optimal conditions, the Rh(0)NCs/GNPs gave the desired product, diphenylacetylene, in a good yield of 87% with 91% selectivity. The Rh(0)NCs/GNPs can be reused without significant loss in its catalytic activity.
      Citation: Catalysts
      PubDate: 2019-10-30
      DOI: 10.3390/catal9110908
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 909: Intramolecular Hydrogen Bonds in Selected
           Aromatic Compounds: Recent Developments

    • Authors: Aneta Jezierska, Peter M. Tolstoy, Jarosław J. Panek, Aleksander Filarowski
      First page: 909
      Abstract: A review of intramolecular hydrogen bonding in ortho-hydroxyaryl Schiff bases, ortho-hydroxyaryl Mannich bases, dipyrrins, ortho-hydroxyaryl ketones, ortho-hydroxyaryl amides, and 4-Bora-3a,4a-diaza-s-indacene (BODIPY) dyes with tautomeric sensors as substituents is presented in this paper. Ortho-hydroxy Schiff and Mannich base derivatives are known as model molecules for analysing the properties of intramolecular hydrogen bonding. The compounds under discussion possess physicochemical features modulated by the presence of strong intramolecular hydrogen bonds. The equilibrium between intra- and inter-molecular hydrogen bonds in BODIPY is discussed. Therefore, the summary can serve as a knowledge compendium of the influence of the hydrogen bond on the molecular properties of aromatic compounds.
      Citation: Catalysts
      PubDate: 2019-10-30
      DOI: 10.3390/catal9110909
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 910: In Situ IR Study on Effect of Alkyl Chain
           Length between Amines on Its Stability against Acidic Gases

    • Authors: Rose Mardie Pacia, Clinton Manianglung, Young Soo Ko
      First page: 910
      Abstract: For the CO2 capture process via the cyclic adsorption/desorption method, one emerging catalyst is the use of amine-functionalized silica. This study focused on comparing the CO2 capture performance of diamines with ethyl and propyl spacers and the degradation species formed after long-term exposure to various acidic gases such as SO2 and NO2 at elevated temperatures. Adsorbents were prepared via the incipient wetness technique and then subjected to thermogravimetric measurements and in situ FT-IR analyses. 2NS-P/Kona95, which contains a propyl spacer, showed fewer degradation species formed based on its IR spectra and better stability with its long-term exposure to various acidic gases. Thus, the incorporation of amines with a large number of nitrogen groups of propyl or longer spacer length could be a promising CO2 capture material.
      Citation: Catalysts
      PubDate: 2019-10-30
      DOI: 10.3390/catal9110910
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 911: Synthesis of a Novel Catalyst MnO/CNTs for
           Microwave-Induced Degradation of Tetracycline

    • Authors: Tianming Liu, Guobao Yuan, Guocheng Lv, Yuxin Li, Libing Liao, Siyao Qiu, Chenghua Sun
      First page: 911
      Abstract: Microwave-induced catalytic degradation (MICD) has been considered as one of the most prospective approaches to remove organic contaminants from water. High-performance catalysts, ideally offering efficient degradation ability, are essential to this process. This work reports the fabrication of manganese oxide on carbon nanotubes (MnO/CNTs) as an efficient catalyst under microwave irradiation (MI) to remove tetracycline (TC) from aqueous solution. The hybrid MnO/CNTs structure shows excellent performance in TC degradation. Combining experimental characterization and theoretical calculations, synergistic mechanisms are revealed: (i) Strong MnO/CNTs interaction stabilizes Mn(II) through interfacial bonding; (ii) high-spin states associated with low coordinated Mn(II) play a major role in MICD; and (iii) superoxide radicals (•O2−) and hydroxyl radicals (•OH) induced by microwave input are identified as the major active species.
      Citation: Catalysts
      PubDate: 2019-10-30
      DOI: 10.3390/catal9110911
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 912: Emissions Control Catalysis

    • Authors: Ioannis Yentekakis, Philippe Vernoux
      First page: 912
      Abstract: Important advances have been achieved over the past years in agriculture, industrial technology, energy, and health, which have contributed to human well-being [...]
      Citation: Catalysts
      PubDate: 2019-10-31
      DOI: 10.3390/catal9110912
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 913: Co(II/III) Complexes with Benzoxazole and
           Benzothiazole Ligands as Efficient Heterogenous Photocatalysts for Organic
           Dyes Degradation

    • Authors: Martyna Szymańska, Włodzimierz Czepa, Cezary Hołubowicz, Renata Świsłocka, Teresa Łuczak, Maciej Kubicki, Joanna Karpińska, Marta A. Fik-Jaskółka, Violetta Patroniak
      First page: 913
      Abstract: The problem of pollution in the current world is growing, however people’s awareness of environmental protection and ecology is also increasing. The aim of the study is to present three new Schiff base compounds with Co(II/III) ions and to assess their photocatalytic activity. The study was supported by cyclic voltammetry technique. In due course the complex 2 revealed as the most effective in AR18 degradation, even more than commercially available TiO2. The search for new photocatalysts able to decompose harmful organic dyes into environmentally friendly basic substances is becoming a new trend in the area of chemistry development.
      Citation: Catalysts
      PubDate: 2019-11-01
      DOI: 10.3390/catal9110913
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 914: Surfactant Imprinting Hyperactivated
           Immobilized Lipase as Efficient Biocatalyst for Biodiesel Production from
           Waste Cooking Oil

    • Authors: Yang, Zhang
      First page: 914
      Abstract: Enzymatic production of biodiesel from waste cooking oil (WCO) could contribute to resolving the problems of energy demand and environment pollutions.In the present work, Burkholderia cepacia lipase (BCL) was activated by surfactant imprinting, and subsequently immobilized in magnetic cross-linked enzyme aggregates (mCLEAs) with hydroxyapatite coated magnetic nanoparticles (HAP-coated MNPs). The maximum hyperactivation of BCL mCLEAs was observed in the pretreatment of BCL with 0.1 mM Triton X-100. The optimized Triton-activated BCL mCLEAs was used as a highly active and robust biocatalyst for biodiesel production from WCO, exhibiting significant increase in biodiesel yield and tolerance to methanol. The results indicated that surfactant imprinting integrating mCLEAs could fix BCL in their active (open) form, experiencing a boost in activity and allowing biodiesel production performed in solvent without further addition of water. A maximal biodiesel yield of 98% was achieved under optimized conditions with molar ratio of methanol-to-WCO 7:1 in one-time addition in hexane at 40 °C. Therefore, the present study displays a versatile method for lipase immobilization and shows great practical latency in renewable biodiesel production.
      Citation: Catalysts
      PubDate: 2019-11-01
      DOI: 10.3390/catal9110914
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 915: Photocatalytic Degradation of Different VOCs
           in the Gas-Phase over TiO2 Thin Films Prepared by Ultrasonic Spray
           Pyrolysis

    • Authors: Ibrahim Dundar, Marina Krichevskaya, Atanas Katerski, Malle Krunks, Ilona Oja Acik
      First page: 915
      Abstract: In this study, we deposited TiO2 thin films onto borosilicate glass by ultrasonic spray pyrolysis at 350 and 450 °C. The aim of study is to determine the effect of deposition temperature on photocatalytic activity of TiO2 thin films and to investigate the performance of TiO2 thin films on photocatalytic degradation of methyl tert-butyl ether (MTBE), acetone, acetaldehyde, and heptane as functions of different operating parameters. TiO2 thin films deposited at 350 and 450 °C have a thickness value of 190 and 330 nm, respectively. All as-prepared TiO2 films possess an anatase crystalline structure. According to the X-ray photon spectroscopy (XPS) study, the TiO2 thin film deposited at 350 °C showed a higher amount of oxygen vacancies and hydroxyl groups on the film surface after UV treatment. The aged-TiO2 thin film deposited at 350 °C showed a water contact angle (WCA) value of 0° after 10 min UV irradiation, showing superhydrophilic surface behavior. The TiO2 film deposited at 350 °C exhibited the highest amount of conversion of MTBE (100%). The results also showed that TiO2 films are capable of photocatalytic degradation of MTBE (100%) and acetaldehyde (approx. 80%) in humid air conditions and high airflow rate. The visible-light-activity of TiO2 thin films was tested with 5 ppm MTBE and acetone. TiO2 thin films deposited at 350 °C with a surface area of 600 cm2 showed 60% of MTBE and 33% of acetone degradation under VIS light.
      Citation: Catalysts
      PubDate: 2019-11-02
      DOI: 10.3390/catal9110915
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 916: Duality in the Mechanism of Hexagonal
           ZnO/CuxO Nanowires Inducing Sulfamethazine Degradation under Solar or
           Visible Light

    • Authors: Yu, Kiwi, Wang, Pulgarin, Rtimi
      First page: 916
      Abstract: This study presents the first evidence for the photocatalytic performance of ZnO/CuxO hexagonal nanowires leading to sulfamethazine (SMT) degradation. The chemical composition of the nanowires was determined by X-ray fluorescence (XRF). The sample with the composition ZnO/Cux = 1.25O led to faster SMT-degradation kinetics. The SMT-degradation kinetics were monitored by high performance liquid chromatography (HPLC). The morphology of the hexagonal nanowires was determined by scanning electron microscopy (SEM) and mapped by EDX. The redox reactions during SMT degradation were followed by X-ray photoelectron spectroscopy (XPS). The interfacial potential between the catalyst surface and SMT was followed in situ under solar and indoor visible light irradiation. SMT-degradation was mediated by reactive oxidative species (ROS). The interfacial charge transfer (IFCT) between ZnO and CuxO is shown to depend on the type of light used (solar or visible light). This later process was found to be iso-energetic due to the potential energy positions of ZnO and CuxO conduction bands (cb). The intervention of surface plasmon resonance (LSPR) species in the SMT degradation is discussed.
      Citation: Catalysts
      PubDate: 2019-11-02
      DOI: 10.3390/catal9110916
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 917: A Short Overview on the Hydrogen Production
           Via Aqueous Phase Reforming (APR) of Cellulose, C6-C5 Sugars and Polyols

    • Authors: Fasolini, Cucciniello, Paone, Mauriello, Tabanelli
      First page: 917
      Abstract: The use of lignocellulosic biomasses for the production of renewable hydrogen is surely among the hot-topic research tasks. In this review, we report on the recent advances in the catalytic conversion of cellulose and its derived C6-C5 sugars (glucose, fructose, and xylose) and polyols (sorbitol and xylitol) into hydrogen via aqueous phase reforming (APR) reactions. The APR processes are considered to be new sustainable catalytic routes for converting the carbohydrate fraction of biomasses into hydrogen at milder reaction conditions if compared with the traditional reforming reactions. Particular emphasis is given to the development of new and active catalysts and to the optimization of reaction conditions that aimed to maximize hydrogen production with a low concentration of CO avoiding, at the same time, the formation of alkanes.
      Citation: Catalysts
      PubDate: 2019-11-03
      DOI: 10.3390/catal9110917
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 918: Editorial Catalysts: Special Issue on Trends
           in Catalytic Wet Peroxide Oxidation Processes

    • Authors: Asunción Quintanilla, Macarena Munoz
      First page: 918
      Abstract: The catalytic wet peroxide oxidation (CWPO) process is an advanced oxidation technology that has shown great potential for the decontamination of wastewater [...]
      Citation: Catalysts
      PubDate: 2019-11-04
      DOI: 10.3390/catal9110918
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 919: Propene Adsorption-Chemisorption Behaviors
           on H-SAPO-34 Zeolite Catalysts at Different Temperatures

    • Authors: Muhammad Usman, Jiang Zhu, Kong Chuiyang, Muhammad Tahir Arslan, Abuzar Khan, Ahmad Galadima, Oki Muraza, Ibrahim Khan, Aasif Helal, Bassem A. Al-Maythalony, Zain H. Yamani
      First page: 919
      Abstract: Propene is an important synthetic industrial product predominantly formed by a methanol-to-olefins (MTO) catalytic process. Propene is known to form oligomers on zeolite catalysts, and paramters to separate it from mixtures and its diffusion properties are difficult to measure. Herein, we explored the adsorption–chemisorption behavior of propene by choosing SAPO-34 zeolites with three different degrees of acidity at various adsorption temperatures in an ultra-high-vacuum adsorption system. H-SAPO-34 zeolites were prepared by a hydrothermal method, and their structural, morphological, and acidic properties were investigated by XRD, SEM, EDX, and temperature-programmed desorption of ammonia (NH3-TPD) analysis techniques. The XRD analysis revealed the highly crystalline structure which posses cubic morphology as confirmed by SEM images. The analysis of adsorption of propene on SAPO-34 revealed that a chemical reaction (chemisorption) was observed between zeolite and propene at room temperature (RT) when the concentration of acidic sites was high (0.158 mmol/g). The reaction was negligible when the concentration of the acidic sites was low (0.1 mmol/g) at RT. However, the propene showed no reactivity with the highly acidic SAPO-34 at low temperatures, i.e., −56 °C (using octane + dry ice), −20 °C (using NaCl + ice), and 0 °C (using ice + water). In general, low-temperature conditions were found to be helpful in inhibiting the chemisorption of propene on the highly acidic H-SAPO-34 catalysts, which can facilitate propene separation and allow for reliable monitoring of kinetic parameters.
      Citation: Catalysts
      PubDate: 2019-11-05
      DOI: 10.3390/catal9110919
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 920: Ag- and Cu-Promoted Mesoporous Ta-SiO2
           Catalysts Prepared by Non-Hydrolytic Sol-Gel for the Conversion of Ethanol
           to Butadiene

    • Authors: Denis D. Dochain, Aleš Stýskalík, Damien P. Debecker
      First page: 920
      Abstract: The direct catalytic conversion of bioethanol to butadiene, also known as the Lebedev process, is one of the most promising solution to replace the petro-based production of this important bulk chemical. Considering the intricate reaction mechanism—where a combination of acid-catalyzed dehydration reactions and metal-catalyzed dehydrogenation have to take place simultaneously—tailor-made bifunctional catalysts are required. We propose to use non-hydrolytic sol-gel (NHSG) chemistry to prepare mesoporous Ta-SiO2 materials which are further promoted by Ag via impregnation. An acetamide elimination route is presented, starting from silicon tetraacetate and pentakis(dimethylamido)tantalum(V), in the presence of a Pluronic surfactant. The catalysts display advantageous texture, with specific surface area in the 600–1000 m² g−1 range, large pore volume (0.6–1.0 mL g−1), an average pore diameter of 4 nm and only a small contribution from micropores. Using an array of characterization techniques, we show that NHSG allows achieving a high degree of dispersion of tantalum, mainly incorporated as single sites in the silica matrix. The presence of these monomeric TaOx active sites is responsible for the much higher dehydration ability, as compared to the corresponding catalyst prepared by impregnation of Ta onto a pristine silica support. We attempt to optimize the butadiene yield by changing the relative proportion of Ta and Ag and by tuning the space velocity. We also demonstrate that Ag or Cu can be introduced directly in one step, during the NHSG process. Copper doping is shown to be much more efficient than silver doping to guide the reaction towards the production of butadiene.
      Citation: Catalysts
      PubDate: 2019-11-05
      DOI: 10.3390/catal9110920
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 921: First-Principles-Based Simulation of an
           Industrial Ethanol Dehydration Reactor

    • Authors: Van der Borght, Alexopoulos, Toch, Thybaut, Marin, Galvita
      First page: 921
      Abstract: The achievement of new economically viable chemical processes often involves the translation of observed lab-scale phenomena into performance in an industrial reactor. In this work, the in silico design and optimization of an industrial ethanol dehydration reactor were performed, employing a multiscale model ranging from nano-, over micro-, to macroscale. The intrinsic kinetics of the elementary steps was quantified through ab initio obtained rate and equilibrium coefficients. Heat and mass transfer limitations for the industrial design case were assessed via literature correlations. The industrial reactor model developed indicated that it is not beneficial to utilize feeds with high ethanol content, as they result in lower ethanol conversion and ethene yield. Furthermore, a more pronounced temperature drop over the reactor was simulated. It is preferred to use a more H2O-diluted feed for the operation of an industrial ethanol dehydration reactor.
      Citation: Catalysts
      PubDate: 2019-11-05
      DOI: 10.3390/catal9110921
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 922: Atomic Layer Deposition ZnO Over-Coated
           Cu/SiO2 Catalysts for Methanol Synthesis from CO2 Hydrogenation

    • Authors: Jinglin Gao, Philip Effah Boahene, Yongfeng Hu, Ajay Dalai, Hui Wang
      First page: 922
      Abstract: Cu-ZnO-based catalysts are of importance for CO2 utilization to synthesize methanol. However, the mechanisms of CO2 activation, the split of the C=O double bond, and the formation of C-H and O-H bonds are still debatable. To understand this mechanism and to improve the selectivity of methanol formation, the combination of strong electronic adsorption (SEA) and atomic layer deposition (ALD) was used to form catalysts with Cu nanoparticles surrounded by a non-uniform ZnO layer, uniform atomic layer of ZnO, or multiple layers of ZnO on porous SiO2. N2 adsorption, H2 temperature-programmed reduction (H2-TPR) X-ray diffraction (XRD), transmission electron microscope (TEM), energy-dispersive X-ray spectroscopy (EDX), CO-chemisorption, CO2 temperature-programmed desorption (CO2-TPD), X-ray adsorption near edge structure (XANES), and extended X-ray absorption fine structure (EXAFS) were used to characterize the catalysts. The catalyst activity was correlated to the number of metallic sites. The catalyst of 5 wt% Cu over-coated with a single atomic layer of ZnO exhibited higher methanol selectivity. This catalyst has comparatively more metallic sites (smaller Cu particles with good distribution) and basic site (uniform ZnO layer) formation, and a stronger interaction between them, which provided necessary synergy for the CO2 activation and hydrogenation to form methanol.
      Citation: Catalysts
      PubDate: 2019-11-06
      DOI: 10.3390/catal9110922
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 923: Cleanup and Conversion of Biomass
           Liquefaction Aqueous Phase to C3–C5 Olefins over ZnxZryOz Catalyst

    • Authors: Stephen D. Davidson, Juan A. Lopez-Ruiz, Matthew Flake, Alan R. Cooper, Yaseen Elkasabi, Marco Tomasi Morgano, Vanessa Lebarbier Dagle, Karl O. Albrecht, Robert A. Dagle
      First page: 923
      Abstract: The viability of using a ZnxZryOz mixed oxide catalyst for the direct production of C4 olefins from the aqueous phase derived from three different bio-oils was explored. The aqueous phases derived from (i) hydrothermal liquefaction of corn stover, (ii) fluidized bed fast pyrolysis of horse litter, and (iii) screw pyrolysis of wood pellets were evaluated as feedstocks. While exact compositions vary, the primary constituents for each feedstock are acetic acid and propionic acid. Continuous processing, based on liquid–liquid extraction, for the cleanup of the inorganic contaminants contained in the aqueous phase was also demonstrated. Complete conversion of the carboxylic acids was achieved over ZnxZryOz catalyst for all the feedstocks investigated. The main reaction products from each of the feedstocks include isobutene (>30% selectivity) and CO2 (>23% selectivity). Activity loss from coking was also observed, thereby rendering deactivation of the ZnxZryOz catalyst, however, complete recovery of catalyst activity was observed following regeneration. Finally, the presence of H2 in the feed was found to facilitate hydrogenation of intermediate acetone, thereby increasing propene production and, consequently, decreasing isobutene production.
      Citation: Catalysts
      PubDate: 2019-11-06
      DOI: 10.3390/catal9110923
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 924: Gas Phase Catalytic Hydrogenation of C4
           Alkynols over Pd/Al2O3

    • Authors: Alberto González-Fernández, Chiara Pischetola, Fernando Cárdenas-Lizana
      First page: 924
      Abstract: Alkenols are commercially important chemicals employed in the pharmaceutical and agro-food industries. The conventional production route via liquid phase (batch) alkynol hydrogenation suffers from the requirement for separation/purification unit operations to extract the target product. We have examined, for the first time, the continuous gas phase hydrogenation (P = 1 atm; T = 373 K) of primary (3-butyn-1-ol), secondary (3-butyn-2-ol) and tertiary (2-methyl-3-butyn-2-ol) C4 alkynols using a 1.2% wt. Pd/Al2O3 catalyst. Post-TPR, the catalyst exhibited a narrow distribution of Pdδ- (based on XPS) nanoparticles in the size range 1-6 nm (mean size = 3 nm from STEM). Hydrogenation of the primary and secondary alkynols was observed to occur in a stepwise fashion (-C≡C- → -C=C- → -C-C-) while alkanol formation via direct -C≡C- → -C-C- bond transformation was in evidence in the conversion of 2-methyl-3-butyn-2-ol. Ketone formation via double bond migration was promoted to a greater extent in the transformation of secondary (vs. primary) alkynol. Hydrogenation rate increased in the order primary < secondary < tertiary. The selectivity and reactivity trends are accounted for in terms of electronic effects.
      Citation: Catalysts
      PubDate: 2019-11-06
      DOI: 10.3390/catal9110924
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 925: Catalyzed Mizoroki-Heck Reaction or C-H
           Activation

    • Authors: Sabine Berteina-Raboin
      First page: 925
      Abstract: In the last few decade, research conducted on the development by catalytic processes of C-C bonds formation on the one hand and on the other hand on the activation of C-H bonds has grown considerably [...]
      Citation: Catalysts
      PubDate: 2019-11-06
      DOI: 10.3390/catal9110925
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 926: In Situ EPR Characterization of a Cobalt
           Oxide Water Oxidation Catalyst at Neutral pH

    • Authors: Yury Kutin, Nicholas Cox, Wolfgang Lubitz, Alexander Schnegg, Olaf Rüdiger
      First page: 926
      Abstract: Here we report an in situ electron paramagnetic resonance (EPR) study of a low-cost, high-stability cobalt oxide electrodeposited material (Co-Pi) that oxidizes water at neutral pH and low over-potential, representing a promising system for future large-scale water splitting applications. Using CW X-band EPR we can follow the film formation from a Co(NO3)2 solution in phosphate buffer and quantify Co uptake into the catalytic film. As deposited, the film shows predominantly a Co(II) EPR signal, which converts into a Co(IV) signal as the electrode potential is increased. A purpose-built spectroelectrochemical cell allowed us to quantify the extent of Co(II) to Co(IV) conversion as a function of potential bias under operating conditions. Consistent with its role as an intermediate, Co(IV) is formed at potentials commensurate with electrocatalytic O2 evolution (+1.2 V, vs. SHE). The EPR resonance position of the Co(IV) species shifts to higher fields as the potential is increased above 1.2 V. Such a shift of the Co(IV) signal may be assigned to changes in the local Co structure, displaying a more distorted ligand field or more ligand radical character, suggesting it is this subset of sites that represents the catalytically ‘active’ component. The described spectroelectrochemical approach provides new information on catalyst function and reaction pathways of water oxidation.
      Citation: Catalysts
      PubDate: 2019-11-06
      DOI: 10.3390/catal9110926
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 927: Ti3+ Defective SnS2/TiO2 Heterojunction
           Photocatalyst for Visible-Light Driven Reduction of CO2 to CO with High
           Selectivity

    • Authors: Aiguo Han, Mei Li, Shengbo Zhang, Xinli Zhu, Jinyu Han, Qingfeng Ge, Hua Wang
      First page: 927
      Abstract: In recent years, defective TiO2-based composite nanomaterials have received much attention in the field of photocatalysis. In this work, TiB2 was used as a precursor to successfully prepare Ti3+ defective TiO2 (TiO2-B) with a truncated bipyramidal structure by a one-step method. Then, the SnS2 nanosheets were assembled onto the as-prepared TiO2-B through simple hydrothermal reaction. TiO2-B exhibits strong visible light absorption properties, but the recombination rate of the photo-generated electron-hole pair was high and does not exhibit ideal photocatalytic performance. Upon introducing SnS2, the heterojunction catalyst SnS2-Ti3+ defective TiO2 (SnS2/TiO2-B) not only possesses the strong light absorption from UV to visible light region, the lowest photo-generated charge recombination rate but also achieves a more negative conduction band potential than the reduction potential of CO2 to CO, and thereby, exhibits the significantly enhanced selectivity and yield of CO in photocatalytic CO2 reduction. Notably, SnS2/TiO2-B produces CO at a rate of 58 µmol·h−1·g−1 with CO selectivity of 96.3% under visible light irradiation, which is 2 and 19 times greater than those of alone TiO2-B and SnS2, respectively. Finally, a plausible photocatalytic mechanism on SnS2/TiO2-B was proposed that the electron transfer between TiO2 and SnS2 follows the Z-scheme mode. Our results present an effective way to gain highly efficient TiO2 based photocatalysts for CO2 reduction by combining different modification methods of TiO2 and make full use of the synergistic effects.
      Citation: Catalysts
      PubDate: 2019-11-06
      DOI: 10.3390/catal9110927
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 928: Organocatalysis and Beyond: Activating
           Reactions with Two Catalytic Species

    • Authors: Arianna Sinibaldi, Valeria Nori, Andrea Baschieri, Francesco Fini, Antonio Arcadi, Armando Carlone
      First page: 928
      Abstract: Since the beginning of the millennium, organocatalysis has been gaining a predominant role in asymmetric synthesis and it is, nowadays, a foundation of catalysis. Synergistic catalysis, combining two or more different catalytic cycles acting in concert, exploits the vast knowledge acquired in organocatalysis and other fields to perform reactions that would be otherwise impossible. Merging organocatalysis with photo-, metallo- and organocatalysis itself, researchers have ingeniously devised a range of activations. This feature review, focusing on selected synergistic catalytic approaches, aims to provide a flavor of the creativity and innovation in the area, showing ground-breaking examples of organocatalysts, such as proline derivatives, hydrogen bond-mediated, Cinchona alkaloids or phosphoric acids catalysts, which work cooperatively with different catalytic partners.
      Citation: Catalysts
      PubDate: 2019-11-06
      DOI: 10.3390/catal9110928
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 929: Deactivation of Cu/SSZ-13 NH3-SCR Catalyst
           by Exposure to CO, H2, and C3H6

    • Authors: Auvray, Mihai, Lundberg, Olsson
      First page: 929
      Abstract: Lean nitric oxide (NOx)-trap (LNT) and selective catalytic reduction (SCR) are efficient systems for the abatement of NOx. The combination of LNT and SCR catalysts improves overall NOx removal, but there is a risk that the SCR catalyst will be exposed to high temperatures and rich exhaust during the LNTs sulfur regeneration. Therefore, the effect of exposure to various rich conditions and temperatures on the subsequent SCR activity of a Cu-exchanged chabazite catalyst was studied. CO, H2, C3H6, and the combination of CO + H2 were used to simulate rich conditions. Aging was performed at 800 °C, 700 °C, and, in the case of CO, 600 °C, in a plug-flow reactor. Investigation of the nature of Cu sites was performed with NH3-temperature-programed desorption (TPD) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) of probe molecules (NH3 and NO). The combination of CO and H2 was especially detrimental to SCR activity and to NH3 oxidation. Rich aging with low reductant concentrations resulted in a significantly larger deactivation compared to lean conditions. Aging in CO at 800 °C caused SCR deactivation but promoted high-temperature NH3 oxidation. Rich conditions greatly enhanced the loss of Brønsted and Lewis acid sites at 800 °C, indicating dealumination and Cu migration. However, at 700 °C, mainly Brønsted sites disappeared during aging. DRIFT spectroscopy analysis revealed that CO aging modified the Cu2+/CuOH+ ratio in favor of the monovalent CuOH+ species, as opposed to lean aging. To summarize, we propose that the reason for the increased deactivation observed for mild rich conditions is the transformation of the Cu species from Z2Cu to ZCuOH, possibly in combination with the formation of Cu clusters.
      Citation: Catalysts
      PubDate: 2019-11-06
      DOI: 10.3390/catal9110929
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 930: Estimation of the Effectiveness Factor for
           Immobilized Enzyme Catalysts through a Simple Conversion Assay

    • Authors: Pedro Valencia, Francisco Ibañez
      First page: 930
      Abstract: A novel methodology to estimate the effectiveness factor (EF) of an immobilized enzyme catalyst is proposed here. The methodology consists of the determination of the productivity of both the immobilized enzyme catalyst and its corresponding soluble enzyme, plotted as a function of the reaction conversion. The ratio of these productivities corresponds to the EF estimator of the catalyst. Conversion curves were simulated in a batch reactor with immobilized enzyme and soluble enzyme for different values of the S0/KM ratio and Thiele modulus (Φ) to demonstrate this hypothesis. Two different reaction orders were tested: first-order kinetic and Michaelis–Menten-based kinetic with product inhibition. The results showed that the ratio of productivities between the immobilized and soluble enzymes followed the behavior profile presented by the EF with satisfactory agreement. This simple methodology to estimate the EF is based on routine conversion experiments, thus avoiding the exhaustive kinetic and mass transfer characterization of the immobilized enzyme catalyst.
      Citation: Catalysts
      PubDate: 2019-11-07
      DOI: 10.3390/catal9110930
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 931: A Polypyrrole-Modified Pd-Ag Bimetallic
           Electrode for the Electrocatalytic Reduction of 4-Chlorophenol

    • Authors: Xuefeng Wei, Laiyuan Zeng, Weiwei Lu, Juan Miao, Ruichang Zhang, Ming Zhou, Jun Zhang
      First page: 931
      Abstract: A polypyrrole-modified bimetallic electrode composed of Pd-Ag on a Ti substrate (Pd-Ag/PPY/Ti) was successfully prepared via a chemical deposition method, and was applied to the electrocatalytic hydrodechlorination of 4-chlorophenol (4-CP) in aqueous solution. The electrode was characterized by cyclic voltammetry (CV), scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Various influences on the dechlorination efficiency of 4-chlorophenol, including applied current, initial pH value, and temperature, were studied. The dechlorination efficiency of 4-CP reached 94% within 120 min under the optimum conditions, i.e., a dechlorination current of 6 mA, an initial pH of 2.30, and a temperature of 303 K. The apparent activation energy of the dechlorination of 4-CP by the Pd-Ag/PPY/Ti electrode was calculated to be 49.6 kJ/mol. The equivalent conversion rate constant kPd was 0.63 L.gPd−1·min−1, which was higher than the findings presented in comparable literature. Thus, a highly effective bimetallic electrode with promising application prospects and low Pd loading was fabricated.
      Citation: Catalysts
      PubDate: 2019-11-07
      DOI: 10.3390/catal9110931
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 932: Impact of a Modified Fenton Process on the
           

    • Authors: Kida, Ziembowicz, Koszelnik
      First page: 932
      Abstract: This paper describes work to assess the possibility of a modified Fenton process being used to remove the hard-to-degrade plasticizer di(2-ethylhexyl) phthalate (DEHP) from the bottom sediments of a reservoir. The modifications in question entail iron(II) ions being replaced by iron(III), as well as facilitation of the process using a chelating agent. Analysis further revolved around the impact of such factors as amounts of reagents, reaction of the environment, initial contents of the contaminant, and the presence of other “competing” contaminants also of a hard-to-decompose nature. As the maximum efficiency of DEHP removal obtained did not exceed 30%, the low susceptibility to degradation is made clear, as is the need for earlier desorption of the contaminant from the matrix. The effect of the modified Fenton process on the content of organic matter and dissolved organic carbon was also considered, as was the tendency to cause selected metals and plant nutrients to leach from bottom sediments.
      Citation: Catalysts
      PubDate: 2019-11-07
      DOI: 10.3390/catal9110932
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 933: Effect of Metal Oxide–Support Interactions
           on Ethylene Oligomerization over Nickel Oxide/Silica–Alumina Catalysts

    • Authors: Ji Sun Yoon, Min Bum Park, Youngmin Kim, Dong Won Hwang, Ho-Jeong Chae
      First page: 933
      Abstract: We investigated the interactions between nickel oxide and silica–alumina supports, which were applied to the catalytic oligomerization of ethylene by powder X-ray diffraction, UV diffuse reflectance spectroscopy, H2 temperature-programmed reduction, and X-ray photoelectron spectroscopy. The catalytic activity was also correlated with the acidity of catalysts determined by NH3 temperature-programmed desorption and pyridine FT-IR spectroscopy. Although all the catalysts had similar Ni contents, their catalytic performances were strongly influenced by the strength of the metal oxide–support interaction. Strong interaction promoted the formation of nickel aluminate on the catalyst surface, and resulted in low catalytic activity due to reducing the amount of nickel oxide active sites. However, weak interaction favored the aggregation of nickel oxide species into larger particles, and thus resulted in low ethylene conversion and selectivity to oligomers. Eventually, the optimal activity was realized at the medium interaction strength, preserving a high amount of both active nickel oxides and acid sites.
      Citation: Catalysts
      PubDate: 2019-11-08
      DOI: 10.3390/catal9110933
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 934: N-Heterocyclic Carbene-Supported Aryl- and
           Alk- oxides of Beryllium and Magnesium

    • Authors: Jacob E. Walley, Yuen-Onn Wong, Lucas A. Freeman, Diane A. Dickie, Robert J. Gilliard
      First page: 934
      Abstract: Recently, we have witnessed significant progress with regard to the synthesis of molecular alkaline earth metal reagents and catalysts. To provide new precursors for light alkaline earth metal chemistry, molecular aryloxide and alkoxide complexes of beryllium and magnesium are reported. The reaction of beryllium chloride dietherate with two equivalents of 1,3-diisopropyl-4,5-dimethylimidizol-2-ylidine (sIPr) results in the formation of a bis(N-heterocyclic carbene) (NHC) beryllium dichloride complex, (sIPr)2BeCl2 (1). Compound 1 reacts with lithium diisopropylphenoxide (LiODipp) or sodium ethoxide (NaOEt) to form the terminal aryloxide (sIPr)Be(ODipp)2 (2) and alkoxide dimer [(sIPr)Be(OEt)Cl]2 (3), respectively. Compounds 2 and 3 represent the first beryllium alkoxide and aryloxide species supported by NHCs. Structurally related dimers of magnesium, [(sIPr)Mg(OEt)Brl]2 (4) and [(sIPr)Mg(OEt)Me]2 (5), were also prepared. Compounds 1-5 were characterized by single crystal X-ray diffraction studies, 1H, 13C, and 9Be NMR spectroscopy where applicable.
      Citation: Catalysts
      PubDate: 2019-11-08
      DOI: 10.3390/catal9110934
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 935: Catalytic Fast Pyrolysis of Lignin Isolated
           by Hybrid Organosolv—Steam Explosion Pretreatment of Hardwood and
           Softwood Biomass for the Production of Phenolics and Aromatics

    • Authors: Ioannis Charisteidis, Polykarpos Lazaridis, Apostolos Fotopoulos, Eleni Pachatouridou, Leonidas Matsakas, Ulrika Rova, Paul Christakopoulos, Konstantinos Triantafyllidis
      First page: 935
      Abstract: Lignin, one of the three main structural biopolymers of lignocellulosic biomass, is the most abundant natural source of aromatics with a great valorization potential towards the production of fuels, chemicals, and polymers. Although kraft lignin and lignosulphonates, as byproducts of the pulp/paper industry, are available in vast amounts, other types of lignins, such as the organosolv or the hydrolysis lignin, are becoming increasingly important, as they are side-streams of new biorefinery processes aiming at the (bio)catalytic valorization of biomass sugars. Within this context, in this work, we studied the thermal (non-catalytic) and catalytic fast pyrolysis of softwood (spruce) and hardwood (birch) lignins, isolated by a hybrid organosolv–steam explosion biomass pretreatment method in order to investigate the effect of lignin origin/composition on product yields and lignin bio-oil composition. The catalysts studied were conventional microporous ZSM-5 (Zeolite Socony Mobil–5) zeolites and hierarchical ZSM-5 zeolites with intracrystal mesopores (i.e., 9 and 45 nm) or nano-sized ZSM-5 with a high external surface. All ZSM-5 zeolites were active in converting the initially produced via thermal pyrolysis alkoxy-phenols (i.e., of guaiacyl and syringyl/guaiacyl type for spruce and birch lignin, respectively) towards BTX (benzene, toluene, xylene) aromatics, alkyl-phenols and polycyclic aromatic hydrocarbons (PAHs, mainly naphthalenes), with the mesoporous ZSM-5 exhibiting higher dealkoxylation reactivity and being significantly more selective towards mono-aromatics compared to the conventional ZSM-5, for both spruce and birch lignin.
      Citation: Catalysts
      PubDate: 2019-11-08
      DOI: 10.3390/catal9110935
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 936: Kinetic Modelling of the Aqueous-Phase
           Reforming of Fischer-Tropsch Water over Ceria-Zirconia Supported
           Nickel-Copper Catalyst

    • Authors: Irene Coronado, Aitor Arandia, Matti Reinikainen, Reetta Karinen, Riikka L. Puurunen, Juha Lehtonen
      First page: 936
      Abstract: In the Fischer–Tropsch (FT) synthesis, a mixture of CO and H2 is converted into hydrocarbons and water with diluted organics. This water fraction with oxygenated hydrocarbons can be processed through aqueous-phase reforming (APR) to produce H2. Therefore, the APR of FT water may decrease the environmental impact of organic waters and improve the efficiency of the FT process. This work aimed at developing a kinetic model for the APR of FT water. APR experiments were conducted with real FT water in a continuous packed-bed reactor at different operating conditions of temperature (210–240 °C), pressure (3.2–4.5 MPa) and weight hourly space velocity (WHSV) (40–200 h−1) over a nickel-copper catalyst supported on ceria-zirconia. The kinetic model considered C1-C4 alcohols as reactants, H2, CO, CO2 and CH4 as the gaseous products, and acetic acid as the only liquid product. The kinetic model included seven reactions, the reaction rates of which were expressed with power law equations. The kinetic parameters were estimated with variances and confidence intervals that explain the accuracy of the model to estimate the outlet liquid composition resulting from the APR of FT water. The kinetic model developed in this work may facilitate the development of APR to be integrated in a FT synthesis process.
      Citation: Catalysts
      PubDate: 2019-11-08
      DOI: 10.3390/catal9110936
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 937: Structure and Catalytic Behavior of Alumina
           Supported Bimetallic Au-Rh Nanoparticles in the Reduction of NO by CO

    • Authors: Wang, Wang, Maeda, Baiker
      First page: 937
      Abstract: Alumina-supported bimetallic AuRh catalysts, as well as monometallic reference catalysts, were examined with regard to their structural and catalytic properties in the reduction of NO by CO. Depending on the molar ratio of Au:Rh, the nanoparticles prepared by borohydride co-reduction of corresponding metal salt solutions had a size of 3.5–6.7 nm. The particles consisted of well-dispersed noble metal atoms with some enrichment of Rh in their surface region. NO conversion of AuRh/Al2O3 shifted to lower temperatures with increasing Rh content, reaching highest activity and highest N2 selectivity for the monometallic Rh/Al2O3 catalyst. This behavior is attributed to the enhanced adsorption of CO on the bimetallic catalyst resulting in unfavorable cationic Rh clusters Rh+-(CO)2. Doping with ceria of AuRh/Al2O3 and Rh/Al2O3 catalysts increased the surface population of metallic Rh sites, which are considered most active for the reduction of NO by CO and enhancement of the formation of intermediate isocyanate (-NCO) surface species and their reaction with NO to form N2 and CO2.
      Citation: Catalysts
      PubDate: 2019-11-08
      DOI: 10.3390/catal9110937
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 938: Hydrogen Production from Aqueous Methanol
           Solutions Using Ti–Zr Mixed Oxides as Photocatalysts under UV
           Irradiation

    • Authors: Pérez-Larios, Rico, Anaya-Esparza, Vargas, González-Silva, Gómez
      First page: 938
      Abstract: The synthesis and characterisation of Ti–Zr mixed oxides containing 1 to 10 wt.% of Zr is herein reported. In addition, the samples were tested as photocatalysts in the generation of hydrogen from aqueous methanol solutions. The solids were prepared by sol-gel and then characterised by X-ray diffraction, high resolution electron microscopy, X-ray photoelectron spectroscopy, physisorption of nitrogen, scanning electron microscopy, UV-vis and Raman spectroscopies. The results show the presence of anatase as a predominant structure and the oxides present larger specific surface areas than that of pure titania. A maximum value of 168 m2/g was determined for the sample with 5 wt.% of zirconium. The calculated band gap energies varied from 3.05 to 3.15 eV. It was observed that the greater the zirconium content in the solid, the higher the generation rate of hydrogen when testing the Ti–Zr solids as photocatalysts. Under our experimental conditions, the best catalyst, Ti–Zr oxide with 10 wt. % Zr, showed a production rate of 2100 μmol of H2/h which was about tenfold higher than that observed for pure titania.
      Citation: Catalysts
      PubDate: 2019-11-08
      DOI: 10.3390/catal9110938
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 939: Progress in Synthesizing Analogues of
           Nitrogenase Metalloclusters for Catalytic Reduction of Nitrogen to Ammonia
           

    • Authors: Yang
      First page: 939
      Abstract: Ammonia (NH3) has played an essential role in meeting the increasing demand for food and the worldwide need for nitrogen (N2) fertilizer since 1913. Unfortunately, the traditional Haber–Bosch process for producing NH3 from N2 is a high energy-consumption process with approximately 1.9 metric tons of fossil CO2 being released per metric ton of NH3 produced. As a very challenging target, any ideal NH3 production process reducing fossil energy consumption and environmental pollution would be welcomed. Catalytic NH3 synthesis is an attractive and promising alternative approach. Therefore, developing efficient catalysts for synthesizing NH3 from N2 under ambient conditions would create a significant opportunity to directly provide nitrogenous fertilizers in agricultural fields as needed in a distributed manner. In this paper, the literature on alternative, available, and sustainable NH3 production processes in terms of the scientific aspects of the spatial structures of nitrogenase metalloclusters, the mechanism of reducing N2 to NH3 catalyzed by nitrogenase, the synthetic analogues of nitrogenase metalloclusters, and the opportunities for continued research are reviewed.
      Citation: Catalysts
      PubDate: 2019-11-08
      DOI: 10.3390/catal9110939
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 940: Size-Controlled Synthesis of Pt Particles on
           TiO2 Surface: Physicochemical Characteristic and Photocatalytic Activity

    • Authors: Zielińska-Jurek, Wei, Janczarek, Wysocka, Kowalska
      First page: 940
      Abstract: Different TiO2 photocatalysts, i.e., commercial samples (ST-01 and P25 with minority of rutile phase), nanotubes, well-crystallized faceted particles of decahedral shape and mesoporous spheres, were used as supports for deposition of Pt nanoparticles (NPs). Size-controlled Pt NPs embedded in TiO2 were successfully prepared by microemulsion and wet-impregnation methods. Obtained photocatalysts were characterized using XRD, TEM, X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) specific surface area, DR/UV-vis and action spectrum analysis. The effect of deposition method, amount of Pt precursor and TiO2 properties on size, distribution, and chemical states of deposited Pt NPs were investigated. Finally, the correlations between the physicochemical properties and photocatalytic activities in oxidation and reduction reactions under UV and Vis light of different Pt-TiO2 photocatalysts were discussed. It was found that, regardless of preparation method, the photoactivity mainly depended on platinum and TiO2 morphology. In view of this, we claim that the tight control of NPs’ morphology allows us to design highly active materials with enhanced photocatalytic performance. Action spectrum analysis for the most active Pt-modified TiO2 sample showed that visible light-induced phenol oxidation is initiated by excitation of platinum surface plasmon, and photocatalytic activity analysis revealed that photoactivity depended strongly on morphology of the obtained Pt-modified TiO2 photocatalysts.
      Citation: Catalysts
      PubDate: 2019-11-08
      DOI: 10.3390/catal9110940
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 941: Decoding Essential Amino Acid Residues in
           

    • Authors: Lynn Sophie Schwardmann, Sarah Schmitz, Volker Nölle, Skander Elleuche
      First page: 941
      Abstract: Non-specific nucleases (NSN) are of interest for biotechnological applications, including industrial downstream processing of crude protein extracts or cell-sorting approaches in microfabricated channels. Bacterial nucleases belonging to the superfamily of phospholipase D (PLD) are featured for their ability to catalyze the hydrolysis of nucleic acids in a metal-ion-independent manner. In order to gain a deeper insight into the composition of the substrate groove of a NSN from Pseudomonas syringae, semi-rational mutagenesis based on a structure homology model was applied to identify amino acid residues on the protein’s surface adjacent to the catalytic region. A collection of 12 mutant enzymes each with a substitution to a positively charged amino acid (arginine or lysine) was produced in recombinant form and biochemically characterized. Mutations in close proximity to the catalytic region (inner ring) either dramatically impaired or completely abolished the enzymatic performance, while amino acid residues located at the border of the substrate groove (outer ring) only had limited or no effects. A K119R substitution mutant displayed a relative turnover rate of 112% compared to the original nuclease. In conclusion, the well-defined outer ring of the substrate groove is a potential target for modulation of the enzymatic performance of NSNs belonging to the PLD superfamily.
      Citation: Catalysts
      PubDate: 2019-11-09
      DOI: 10.3390/catal9110941
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 942: Synthesis of Tri- and Disubstituted
           Fluorenols and Derivatives Thereof Using Catalytic [2+2+2]
           Cyclotrimerization

    • Authors: Ilaria Caivano, Reinhard P. Kaiser, Florian Schnurrer, Jiří Mosinger, Ivana Císařová, David Nečas, Martin Kotora
      First page: 942
      Abstract: A method for regioselective synthesis of 2,4-disubstituted and more highly substituted fluorenols using catalytic [2+2+2]cyclotrimerization of mono- and disubstituted diynes with terminal alkynes was explored. In the former case, the preferential formation of the 2,4-regioisomers was achieved in the presence of Cp*Ru(cod)Cl, whereas Rh-based catalysts tended to provide 3,4-regioisomers as the major products. The 2,4-disubstituted fluorenols were converted into the corresponding 9,9′-spirobifluorene derivatives and their structural and photophysical properties were evaluated.
      Citation: Catalysts
      PubDate: 2019-11-09
      DOI: 10.3390/catal9110942
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 943: Novel Functionality of Lithium-Impregnated
           Titania as Nanocatalyst

    • Authors: Indu Ambat, Varsha Srivastava, Esa Haapaniemi, Mika Sillanpää
      First page: 943
      Abstract: The present work incorporates the synthesis of a multifunctional catalyst for the transesterification of waste cooking oil (WCO) to biodiesel and recovery of rare earth elements (REEs). For this purpose, TiO2 nanoparticles and TiO2 doped with lithium ions were prepared. The influence of lithium ions on the catalytic performance of TiO2 was attained by impregnation of the different molar ratios of lithium hydroxide to bare TiO2. Then each catalyst was screened for catalytic conversion of WCO to fatty acid methyl ester (FAME) and also for REEs recovery. All synthesized materials were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) analysis, and Hammett indicator for the basicity test. The obtained biodiesel was characterized by gas chromatography with mass spectrometry (GC-MS), 1H, and 13C nuclear magnetic resonance (NMR). Moreover, the physical parameters of the synthesized biodiesel were also determined. The REEs recovery efficiency of synthesized nanomaterials was investigated, and the percentage of REEs removal was determined by inductively-coupled plasma optical emission spectroscopy (ICP-OES).
      Citation: Catalysts
      PubDate: 2019-11-09
      DOI: 10.3390/catal9110943
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 944: Ni/NiO Nanocomposites with Rich Oxygen
           Vacancies as High-Performance Catalysts for Nitrophenol Hydrogenation

    • Authors: Jun Zhou, Yue Zhang, Song Li, Jing Chen
      First page: 944
      Abstract: Heterogeneous catalysis often involves charge transfer between adsorbed molecules and the surface of catalyst, and thus their activity depends on the surface charge density. The efficiency of charge transfer could be optimized by adjusting the concentration of oxygen vacancies (Ov). In this work, hexagonal Ni(OH)2 nanoparticles were initially synthesized by a hydrothermal process using aluminum powder as the sacrificial agent, and were then converted into 2D Ni/NiO nanocomposites through in situ reduction in hydrogen flow. The oxygen vacancy concentration in the NiO nanosheet could be well-controlled by adjusting the reduction temperature. This resulted in strikingly high activities for hydrogenation of nitrophenol. The Ni/NiO nanocomposite could easily be recovered by a magnetic field for reuse. The present finding is beneficial for producing better hydrogenation catalysts and paves the way for the design of highly efficient catalysts.
      Citation: Catalysts
      PubDate: 2019-11-11
      DOI: 10.3390/catal9110944
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 945: Irrigation Combined with Aeration Promoted
           Soil Respiration through Increasing Soil Microbes, Enzymes, and Crop
           Growth in Tomato Fields

    • Authors: Hui Chen, Zihui Shang, Huanjie Cai, Yan Zhu
      First page: 945
      Abstract: Soil respiration (Rs) is one of the major components controlling the carbon budget of terrestrial ecosystems. Aerated irrigation has been proven to increase Rs compared with the control, but the mechanisms of CO2 release remain poorly understood. The objective of this study was (1) to test the effects of irrigation, aeration, and their interaction on Rs, soil physical and biotic properties (soil water-filled pore space, temperature, bacteria, fungi, actinomycetes, microbial biomass carbon, cellulose activity, dehydrogenase activity, root morphology, and dry biomass of tomato), and (2) to assess how soil physical and biotic variables control Rs. Therefore, three irrigation levels were included (60%, 80%, and 100% of full irrigation). Each irrigation level contained aeration and control. A total of six treatments were included. The results showed that aeration significantly increased total root length, dry biomass of leaf, stem, and fruit compared with the control (p < 0.05). The positive effect of irrigation on dry biomass of leaf, fruit, and root was significant (p < 0.05). With respect to the control, greater Rs under aeration (averaging 6.2% increase) was mainly driven by soil water-filled pore space, soil bacteria, and soil fungi. The results of this study are helpful for understanding the mechanisms of soil CO2 release under aerated subsurface drip irrigation.
      Citation: Catalysts
      PubDate: 2019-11-11
      DOI: 10.3390/catal9110945
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 946: Kinetic Monte-Carlo Simulation of Methane
           Steam Reforming over a Nickel Surface

    • Authors: Palawat Unruean, Teetuch Plianwong, Sirawit Pruksawan, Boonyarach Kitiyanan, Robert M. Ziff
      First page: 946
      Abstract: A kinetic Monte-Carlo model was developed in order to simulate the methane steam reforming and kinetic behavior of this reaction. There were 34 elementary step reactions that were used, based on the Langmuir–Hinshelwood mechanism, over a nickel catalyst. The simulation was investigated at a mole fraction of methane between 0.1 and 0.9, temperature of 600 to 1123 K, and total pressure of up to 40 bar. The simulated results were collected at a steady state and were compared with the previously reported experiments. The fractional coverages of the adsorbed species and the production rates of H2, CO, and CO2 were evaluated, and the effects of the reaction temperature, feed concentration, and total pressure of reactants were also investigated. The simulation results showed a similar trend with previous experimental results, and suggested the appropriate conditions for this reaction, which were a total pressure of 10 bar, with the mole fraction of methane in a range of 0.4–0.5.
      Citation: Catalysts
      PubDate: 2019-11-11
      DOI: 10.3390/catal9110946
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 947: {CeO2/Bi2Mo1−xRuxO6} and
           {Au/Bi2Mo1−xRuxO6} Catalysts for Low-Temperature CO Oxidation

    • Authors: Edson Edain González, Ricardo Rangel, Javier Lara, Pascual Bartolo-Pérez, Juan José Alvarado-Gil, Donald Homero Galván, Rafael García
      First page: 947
      Abstract: Nowadays, one of the most important challenges that humanity faces is to find alternative ways of reducing pollutant emissions. CeO2/Bi2Mo1−xRuxO6 and Au/Bi2Mo1−xRuxO6 catalysts were prepared to efficiently transform carbon monoxide (CO) to carbon dioxide (CO2) at low temperatures. The systems were prepared in a two-step process. First, Bi2Mo1−xRuxO6 supports were synthesized through the hydrothermal procedure under microwave heating. Then, CeO2 was deposited on Bi2Mo1−xRuxO6 using the wet impregnation method, while the incipient impregnation method was selected to deposit gold nanoparticles. The CeO2/Bi2Mo1−xRuxO6 and Au/Bi2Mo1−xRuxO6 catalysts were characterized using SEM microscopy and XRD. Furthermore, energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy were used. Tests were carried out for the supported catalysts in CO oxidation, and high conversion values, nearing 100%, was observed in a temperature range of 100 to 250 °C. The results showed that the best system was the Au/Bi2Mo0.95Ru0.05O6 catalyst, with CO oxidation starting at 50 °C and reaching 100% conversion at 186 °C.
      Citation: Catalysts
      PubDate: 2019-11-12
      DOI: 10.3390/catal9110947
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 948: Facile Synthesis of High Performance Iron
           Oxide/Carbon Nanocatalysts Derived from the Calcination of Ferrocenium for
           the Decomposition of Methylene Blue

    • Authors: Thinnaphat Poonsawat, Thanyaphat Techalertmanee, Peerapong Chumkaeo, Isti Yunita, Titiya Meechai, Montree Namkajorn, Soraya Pornsuwan, Ekasith Somsook
      First page: 948
      Abstract: Iron oxide/carbon nanocatalysts were successfully synthesized by the calcination of ferrocenium at high temperatures ranging from 500 to 900 °C. Then the synthesized nanocomposites were characterized by XRD (X-Ray Diffraction), TEM (Transmission Electron Microscopy), VSM (Vibrating-Sample Magnetometry), BET (Brunauer-Emmett-Teller surface area measurements), TGA (Thermogravimetric Analysis), XPS (X-Ray Photoelectron Spectroscopy), EPR (Electron Paramagnetic Resonance), and CHN elemental analysis. The prepared nanocatalysts were applied for the decomposition of methylene blue as a model in wastewater treatment. It was unexpected to discover that the prepared nanocatalysts were highly active for the reaction with methylene blue in the dark even though no excess of hydrogen peroxide was added. The nanocatalyst calcined at 800 °C exhibited the rod shape with the best catalytic activity. The nanocatalysts could be reused for 12 times without the significant loss of the catalytic activity.
      Citation: Catalysts
      PubDate: 2019-11-12
      DOI: 10.3390/catal9110948
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 949: The Sonophotocatalytic Degradation of
           Pharmaceuticals in Water by MnOx-TiO2 Systems with Tuned Band-Gaps

    • Authors: Zahra Khani, Dalma Schieppati, Claudia L. Bianchi, Daria C. Boffito
      First page: 949
      Abstract: Advanced oxidation processes (AOPs) are technologies to degrade organic pollutants to carbon dioxide and water with an eco-friendly approach to form reactive hydroxyl radicals. Photocatalysis is an AOP whereby TiO2 is the most adopted photocatalyst. However, TiO2 features a wide (3.2 eV) and fast electron-hole recombination. When Mn is embedded in TiO2, it shifts the absorption wavelength towards the visible region of light, making it active for natural light applications. We present a systematic study of how the textural and optical properties of Mn-doped TiO2 vary with ultrasound applied during synthesis. We varied ultrasound power, pulse length, and power density (by changing the amount of solvent). Ultrasound produced mesoporous MnOx-TiO2 powders with a higher surface area (101–158 m2 g−1), pore volume (0-13–0.29 cc g−1), and smaller particle size (4–10 µm) than those obtained with a conventional sol-gel method (48–129 m2 g−1, 0.14–0.21 cc g−1, 181 µm, respectively). Surprisingly, the catalysts obtained with ultrasound had a content of brookite that was at least 28%, while the traditional sol-gel samples only had 7%. The samples synthesized with ultrasound had a wider distribution of the band-gaps, in the 1.6–1.91 eV range, while traditional ones ranged from 1.72 eV to 1.8 eV. We tested activity in the sonophotocatalytic degradation of two model pollutants (amoxicillin and acetaminophen). The catalysts synthesized with ultrasound were up to 50% more active than the traditional samples.
      Citation: Catalysts
      PubDate: 2019-11-12
      DOI: 10.3390/catal9110949
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 950: In-Situ Arc Discharge-Derived
           FeSn2/Onion-Like Carbon Nanocapsules as Improved Stannide-Based
           Electrocatalytic Anode Materials for Lithium-Ion Batteries

    • Authors: Dandan Han, Amrita Chatterjee, Long Hin Man, Siu Wing Or
      First page: 950
      Abstract: Core/shell-structured FeSn2/onion-like carbon (FeSn2/OLC) nanocapsules of confined size range of sub-50 nm are synthesized via an in-situ arc-discharge process, and are evaluated in comparison with FeSn2 nanoparticles as an improved stannide-based electrocatalytic anode material for Li-ion batteries (LIBs). The in-situ arc-discharge process allows a facile one-pot procedure for forming crystalline FeSn2 stannide alloy nanoparticle cores coated by defective OLC thin shells in addition to a confined crystal growth of the FeSn2 nanoparticle cores. The LIB cells assembled using the FeSn2/OLC nanocapsules as the electrocatalytic anodes exhibit superior full specific discharge capacity of 519 mAh·g−1 and specific discharge capacity retention of ~62.1% after 100 charge-discharge cycles at 50 mA·g−1 specific current. The electrochemical stability of FeSn2/OLC nanocapsules is demonstrated from the good cycle stability of the LIBs with a high specific discharge capacity retention of 67.5% on a drastic change in specific current from 4000 to 50 mA·g−1. A formation mechanism is proposed to describe the confined crystal growth of the FeSn2 nanoparticle cores and the formation of the FeSn2/OLC core/shell structure. The observed electrochemical performance enhancement is ascribed to the synergetic effects of the enabling of a reversible lithiation process during charge-discharge of the LIB cells by the FeSn2 nanoparticle cores as well as the protection of the FeSn2 nanoparticle cores from volume change-induced pulverization and solid electrolyte interphase-induced passivation by the OLC shells.
      Citation: Catalysts
      PubDate: 2019-11-13
      DOI: 10.3390/catal9110950
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 951: Novel Cobalt Complex as an Efficient
           Catalyst for Converting CO2 into Cyclic Carbonates under Mild Conditions

    • Authors: Wei Fan, Wen-Zhen Wang, Li Wang, Xin-Gang Jia, Lei-Lei Li, Tian-Cun Xiao, Peter P. Edwards
      First page: 951
      Abstract: Based on the ligand H2dpPzda (1), a novel cobalt complex [Co(H2dpPzda)(NCS)2]·CH3OH(2) has been synthesized and characterized. The Complex 2 exhibited excellent catalytic performance for converting CO2 into cyclic carbonates under mild conditions. For propylene oxide (PO) and CO2 synthesis of propylene carbonate (PC), the catalytic system showed a remarkable TOF as high as 29,200 h−1. The catalytic system also showed broad substrate scope of epoxide. Additionally, the catalyst could be recycled to maintain the integrity of the structure and remained equal to the level of its catalytic activity even after seven catalytic rounds. Additionally, a possible catalytic mechanism was proposed due to the high catalytic activity which might be owing to the synergism of Lewis acidic metal centers and N group.
      Citation: Catalysts
      PubDate: 2019-11-14
      DOI: 10.3390/catal9110951
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 952: Performance of a Ni-Cu-Co/Al2O3 Catalyst on
           in-situ Hydrodeoxygenation of Bio-derived Phenol

    • Authors: Huiyuan Xue, Xingxing Gong, Jingjing Xu, Rongrong Hu
      First page: 952
      Abstract: The in-situ hydrodeoxygenation of bio-derived phenol is an attractive routine for upgrading bio-oils. Herein, an active trimetallic Ni-Cu-Co/Al2O3 catalyst was prepared and applied in the in-situ hydrodeoxygenation of bio-derived phenol. Comparison with the monometallic Ni/Al2O3 catalyst and the bimetallic Ni-Co/Al2O3 and Ni-Cu/Al2O3 catalysts, the Ni-Cu-Co/Al2O3 catalyst exhibited the highest catalytic activity because of the formation of Ni-Cu-Co alloy on the catalyst characterized by using X-ray powder diffraction (XRD), temperature programmed reduction (TPR), N2 physisorption, scanning electron microscope (SEM), and transmission electron microscope (TEM). The phenol conversion of 100% and the cyclohexane yield of 98.3% could be achieved in the in-situ hydrodeoxygenation of phenol at 240 °C and 4 MPa N2 for 6 h. The synergistic effects of Ni with Cu and Co of the trimetallic Ni-Cu-Co/Al2O3 catalyst played a significant role in the in-situ hydrodeoxygenation process of phenol, which not only had a positive effect on the production of hydrogen but also owned an excellent hydrogenolysis activity to accelerate the conversion of cyclohexanol to cyclohexane. Furthermore, the catalyst also exhibited excellent recyclability and good potential for the upgrading of bio-oils.
      Citation: Catalysts
      PubDate: 2019-11-14
      DOI: 10.3390/catal9110952
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 953: Study on the Catalytic Pyrolysis Mechanism
           of Lignite by Using Extracts as Model Compounds

    • Authors: Jianwei Liu, Qian Zhang, Litong Liang, Wei Huang
      First page: 953
      Abstract: Understanding the catalytic pyrolysis mechanism of lignite is of great significance for obtaining a high yield of the target products or designing high-efficiency catalysts, which are generally derived by using simple model compounds, while the ordinary model compounds cannot represent the real atmosphere of lignite pyrolysis owing to the simple structures and single reactions. Based on the coal two-phase model, the extractable compounds are the important compositions of coal, which can reflect the partial characteristics of raw coal while obtaining a high extraction yield. Hence, a better understanding of the interaction between the coal structure and catalyst can be inferred by using a mobile phase in coal as model compounds instead of conventional simple compounds. In this work, tetrahydrofuran extracts of lignite were chosen as model compounds to study the catalytic pyrolysis mechanism with separate addition of Fe(NO3)3 and FeCl3 by using a thermogravimetric combined with mass spectrometry. It was found that about 77.88% of the extracts were vaporized before 700 °C, and the residual yield was 22.12%. With the separate addition of 5 wt % of Fe(NO3)3 and FeCl3, the conversion of the extracts increased to 84.38% and 89.66%. Meanwhile, the final temperature decreased to 650 and 550 °C, respectively. The addition of Fe(NO3)3 and FeCl3 promoted the breakage of aliphatic chains at approximately 150 °C, leading to the generation of CH4 and H2 in the temperature range 100–200 °C, which were nearly invisible for that without catalyst. The addition of iron-based catalysts allowed more CO2 formation at approximately 200 °C since they enabled efficient promotion of the cleavage of carboxyl functionals at lower temperatures. The enlarged peak of H2O and CH4 at approximately 500 °C means that iron-based catalysts are significant for the cleavage of methoxy groups in the catalytic respect. Aromatic side chains facilitated cracking at approximately 500 °C, leading to more light aliphatics and aromatics generation in this temperature range.
      Citation: Catalysts
      PubDate: 2019-11-14
      DOI: 10.3390/catal9110953
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 954: Nitrogen and Cobalt Co-Coped Carbon
           Materials Derived from Biomass Chitin as High-Performance Electrocatalyst
           for Aluminum-Air Batteries

    • Authors: Mi Wang, Jian Ma, Haoqi Yang, Guolong Lu, Shuchen Yang, Zhiyong Chang
      First page: 954
      Abstract: Development of convenient, economic electrocatalysts for oxygen reduction reaction (ORR) in alkaline medium is of great significance to practical applications of aluminum-air batteries. Herein, a biomass chitin-derived carbon material with high ORR activities has been prepared and applied as electrocatalysts in Al-air batteries. The obtained cobalt, nitrogen co-doped carbon material (CoNC) exhibits the positive onset potential 0.86 V vs. RHE (reversible hydrogen electrode) and high-limiting current density 5.94 mA cm−2. Additionally, the durability of the CoNC material in alkaline electrolyte shows better stability when compared to the commercial Pt/C catalyst. Furthermore, the Al-air battery using CoNC as an air cathode catalyst provides the power density of 32.24 mW cm−2 and remains the constant discharge voltage of 1.17 V at 20 mA cm−2. This work not only provides a facile method to synthesize low-cost and efficient ORR electrocatalysts for Al-air batteries, but also paves a new way to explore and utilize high-valued biomass materials.
      Citation: Catalysts
      PubDate: 2019-11-14
      DOI: 10.3390/catal9110954
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 955: Gold(I) Complexes with Ferrocenylphosphino
           Sulfonate Ligands: Synthesis and Application in the Catalytic Addition of
           Carboxylic Acids to Internal Alkynes in Water

    • Authors: Javier Francos, María Esther Moreno-Narváez, Victorio Cadierno, Diego Sierra, Katherine Ariz, Johana Gómez
      First page: 955
      Abstract: The synthesis and characterization of novel gold(I) complexes containing hydrophilic ferrocenylphosphino sulfonate ligands, i.e., compounds [AuCl{(η5-C5H3PR2(SO3iPr))Fe(η5-C5H5)}] (R = Ph (2a), p-Tol (2b), Cy (2c)), are presented, including a single-crystal X-ray diffraction study on 2a. Complexes 2a–c were checked as catalysts for the intermolecular addition of carboxylic acids to nonactivated internal alkynes using water as a green reaction medium. The best results in terms of activity were obtained with 2a in combination with AgOAc, which was able to promote the selective anti addition of a variety of aromatic, aliphatic, and α,β-unsaturated carboxylic acids to both symmetrical and unsymmetrical internal alkynes at 60 °C, employing metal loadings of only 2 mol %.
      Citation: Catalysts
      PubDate: 2019-11-14
      DOI: 10.3390/catal9110955
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 956: Low-Temperature Selective Catalytic
           Reduction of NO with NH3 over Natural Iron Ore Catalyst

    • Authors: Husnain, Wang, Fareed
      First page: 956
      Abstract: The selective catalytic reduction of NO with NH3 at low temperatures has been investigated with natural iron ore catalysts. Four iron ore raw materials from different locations were taken and processed to be used as catalysts. The methods of X-ray diffraction (XRD), X-ray fluorescence (XRF), Brunauer-Emmett-Teller (BET), X-ray photoelectron spectroscopy (XPS), hydrogen temperature-programmed reduction (H2-TPR), ammonia temperature-programmed desorption (NH3-TPD), scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR) were used to characterize the materials. The results showed that the sample A (comprised mainly of α-Fe2O3 and γ-Fe2O3), calcined at 250 °C, achieved excellent selective catalytic reduction (SCR) activity (above 80% at 170–350 °C) and N2 selectivity (above 90% up to 250 °C) at low temperatures. Suitable calcination temperature, large surface area, high concentration of surface-adsorbed oxygen, good reducibility, lots of acid sites and adsorption of the reactants were responsible for the excellent SCR performance of the iron ore. However, the addition of H2O and SO2 in the feed gas showed some adverse effects on the SCR activity. The FT-IR analysis indicated the formation of sulfate salts on the surface of the catalyst during the SCR reaction in the presence of SO2, which could cause pore plugging and result in the suppression of the catalytic activity.
      Citation: Catalysts
      PubDate: 2019-11-14
      DOI: 10.3390/catal9110956
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 957: Developmental Study of Soot-Oxidation
           Catalysts for Fireplaces: The Effect of Binder and Preparation Techniques
           on Catalyst Texture and Activity

    • Authors: Pauliina Nevalainen, Niko Kinnunen, Mika Suvanto
      First page: 957
      Abstract: An awareness of increasing climate and health problems has driven the development of new functional and affordable soot-oxidation catalysts for stationary sources, such as fireplaces. In this study, Al(OH)3, water glass and acidic aluminium phosphate binder materials were mixed with soot-oxidation catalysts. The effect of the binder on the performance of the Ag/La-Al2O3 catalyst was examined, while the Pt/La-Al2O3 catalyst bound with Al(OH)3 was used as a reference. Soot was oxidised above 340 °C on the Ag/La-Al2O3 catalyst, but at 310 °C with same catalyst bound with Al(OH)3. The addition of water glass decreased the catalytic performance because large silver crystals and agglomeration resulted in a blockage of the support material’s pores. Pt/La-Al2O3 bound with Al(OH)3 was ineffective in a fireplace environment. We believe that AgOx is the active form of silver in the catalyst. Hence, Ag/La-Al2O3 was shown to be compatible with the Al(OH)3 binder as an effective catalyst for fireplace soot oxidation.
      Citation: Catalysts
      PubDate: 2019-11-15
      DOI: 10.3390/catal9110957
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 958: Highly Selective pH-Dependent Ozonation of
           Cyclohexane over Mn/γ-Al2O3 Catalysts at Ambient Reaction Conditions

    • Authors: Siphumelele Thandokwazi Mkhondwane, Viswanadha Srirama Rajasekhar Pullabhotla
      First page: 958
      Abstract: The selective oxidation of cyclohexane to a mixture of cyclohexanol and cyclohexanone (KA oil) is one of the imperative reactions in industrial processes. In this study, the catalytic performance of manganese-supported gamma alumina (Mn/γ-Al2O3) catalysts is investigated in the selective oxidation of cyclohexane at ambient conditions using ozone. The catalysts were prepared by the wet impregnation method, and their physio-chemical properties were studied by Fourier Transform Infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) spectroscopy, Scanning Electron Microscopy-Energy Dispersive X-ray spectroscopy (SEM-EDX), Transmission Electron Microscopy (TEM), Inductively Coupled Plasma (ICP) spectroscopy, and Brunauer Emmett and Teller (BET). The reaction conditions were optimised considering various parameters such as reaction time, pH, and various percentages of the manganese supported in gamma alumina. The oxidation of cyclohexane was conducted in an impinger reactor unit at pH 3, 7, and 11 for 1 h of ozonation time. The aliquots were collected after 30 min and 1 h of ozonation time and analysed with GC-MS and FT-IR spectroscopy. The 2.5% Mn/γ-Al2O3 catalyst exhibited a significantly enhanced catalytic performance at pH 3 and 7 with a percentage conversion of 9% and 15% at pH 3 and 7, respectively, after 30 min of ozonation time. However, after 1 h of ozonation time, the percentage conversions were increased to 23% and 29% at pH 3 and 7, respectively. At pH 11, 5% Mn/γ-Al2O3 exhibit high catalytic performance with a percentage conversion of 19% and 31% after 30 minutes and 1 h of ozonation time, respectively. The percentage selectivity obtained is 100% toward KA oil and/or cyclohexanone depending on pH and reaction time.
      Citation: Catalysts
      PubDate: 2019-11-15
      DOI: 10.3390/catal9110958
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 959: The Potential Applications of Bacillus sp.
           and Pseudomonas sp. Strains with Antimicrobial Activity against
           Phytopathogens, in Waste Oils and the Bioremediation of Hydrocarbons

    • Authors: Mariana-Gratiela Soare (Vladu), Elena Simina Lakatos, Nicoleta Ene, Nereida Malo (Dalanaj), Ovidiu Popa, Narcisa Babeanu
      First page: 959
      Abstract: Biodegradation is one of the primary mechanisms for the elimination of petroleum and other hydrocarbon pollutants from the environment. This study presents the results obtained with two newly isolated microorganisms and their potential applications in bioremediation, agriculture, and industrial fields. Twenty-five strains of microorganisms were isolated from plant materials and were subject to a selection process on the basis of antimicrobial activity. Two bacterial strains, respectively Bacillus mycoides (Bm) and Pseudomonas putida (B1), were selected for further experiments, based on the largest inhibition zones against the phytopathogens Erwinia carotovora and Xanthomonas campestris. The production of biosurfactants and enzymes was evaluated in specific media. In order to assess the production of biosurfactants, submerged bioprocesses were carried out on Yeast Malt Peptone Glucose (YMPG), M44, Luria-Bertani (LB), and King B media (KB); the supernatants were used to form emulsions with heptane, octane, and sunflower oil, and the emulsifying indices were determined.
      Citation: Catalysts
      PubDate: 2019-11-15
      DOI: 10.3390/catal9110959
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 960: Ionic, Core-Corona Polymer
           Microsphere-Immobilized MacMillan Catalyst for Asymmetric Diels-Alder
           Reaction

    • Authors: Md. Wali Ullah, Naoki Haraguchi
      First page: 960
      Abstract: The improvement of the catalytic activity of a heterogeneous chiral catalyst is one of the most critical issues, as are its recovery and reuse. The design of a heterogeneous chiral catalyst, including the immobilization method and the support polymer, is of significance for the catalytic activity in asymmetric reactions. An ionic, core-corona polymer microsphere-immobilized MacMillan catalyst (ICCC) was successfully synthesized by the neutralization reaction of sulfonic acid functionalized core-corona polymer microsphere (CCM–SO3H) with a chiral imidazolidinone precursor. We selected the core-corona polymer microsphere as the polymer support for the improvement of catalytic activity and recovery. The MacMillan catalyst was immobilized onto the pendant position of the corona with ionic bonding. ICCC exhibited excellent enantioselectivity up to 92% enantiomeric excess (ee) (exo) and >99% ee (endo) in the asymmetric Diels-Alder (DA) reaction of (E)-cinnamaldehyde and 1,3-cyclopentadiene. ICCC was quantitatively recovered by centrifugation because of the microsphere structure. The recovered ICCC was reused without significant loss of the enantioselectivity.
      Citation: Catalysts
      PubDate: 2019-11-15
      DOI: 10.3390/catal9110960
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 961: Truncated Prosequence of Rhizopus oryzae
           Lipase: Key Factor for Production Improvement and Biocatalyst Stability

    • Authors: Josu López-Fernández, Juan J. Barrero, M. Dolors Benaiges, Francisco Valero
      First page: 961
      Abstract: Recombinant Rhizopus oryzae lipase (mature sequence, rROL) was modified by adding to its N-terminal 28 additional amino acids from the C-terminal of the prosequence (proROL) to obtain a biocatalyst more suitable for the biodiesel industry. Both enzymes were expressed in Pichia pastoris and compared in terms of production bioprocess parameters, biochemical properties, and stability. Growth kinetics, production, and yields were better for proROL harboring strain than rROL one in batch cultures. When different fed-batch strategies were applied, lipase production and volumetric productivity of proROL-strain were always higher (5.4 and 4.4-fold, respectively) in the best case. rROL and proROL enzymatic activity was dependent on ionic strength and peaked in 200 mM Tris-HCl buffer. The optimum temperature and pH for rROL were influenced by ionic strength, but those for proROL were not. The presence of these amino acids altered lipase substrate specificity and increased proROL stability when different temperature, pH, and methanol/ethanol concentrations were employed. The 28 amino acids were found to be preferably removed by proteases, leading to the transformation of proROL into rROL. Nevertheless, the truncated prosequence enhanced Rhizopus oryzae lipase heterologous production and stability, making it more appropriate as industrial biocatalyst.
      Citation: Catalysts
      PubDate: 2019-11-15
      DOI: 10.3390/catal9110961
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 962: Clostridium sp. as Bio-Catalyst for Fuels
           and Chemicals Production in a Biorefinery Context

    • Authors: Vanessa Liberato, Carolina Benevenuti, Fabiana Coelho, Alanna Botelho, Priscilla Amaral, Nei Pereira, Tatiana Ferreira
      First page: 962
      Abstract: Clostridium sp. is a genus of anaerobic bacteria capable of metabolizing several substrates (monoglycerides, diglycerides, glycerol, carbon monoxide, cellulose, and more), into valuable products. Biofuels, such as ethanol and butanol, and several chemicals, such as acetone, 1,3-propanediol, and butyric acid, can be produced by these organisms through fermentation processes. Among the most well-known species, Clostridium carboxidivorans, C. ragsdalei, and C. ljungdahlii can be highlighted for their ability to use gaseous feedstocks (as syngas), obtained from the gasification or pyrolysis of waste material, to produce ethanol and butanol. C. beijerinckii is an important species for the production of isopropanol and butanol, with the advantage of using hydrolysate lignocellulosic material, which is produced in large amounts by first-generation ethanol industries. High yields of 1,3 propanediol by C. butyricum are reported with the use of another by-product from fuel industries, glycerol. In this context, several Clostridium wild species are good candidates to be used as biocatalysts in biochemical or hybrid processes. In this review, literature data showing the technical viability of these processes are presented, evidencing the opportunity to investigate them in a biorefinery context.
      Citation: Catalysts
      PubDate: 2019-11-15
      DOI: 10.3390/catal9110962
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 963: Preparation of Chloromethylated
           Pitch–Based Hyper–Crosslinked Polymers and An Immobilized Acidic Ionic
           Liquid as A Catalyst for the Synthesis of Biodiesel

    • Authors: Baoyou Pei, Xiaoyan Xiang, Ting Liu, Dongliang Li, Chaoyang Zhao, Rongxing Qiu, Xiaoyan Chen, Jinqing Lin, Xiaoyan Luo
      First page: 963
      Abstract: Hyper-crosslinking polymers and its immobilized acid ionic liquid catalyst were prepared using cheap pitch, as a monomer, through hyper-crosslinking reactions and allyl chloride, as a chlorine source, for chloromethylation and further grafting with imidazole and functionalizing with sulfonic acid. The polymers were characterized by FE-SEM, FTIR, TG, and nitrogen sorption. The grafting ratios of the chloromethylated pitch-based hyper-crosslinked polymer (HCPpitch–CH2–Cl) and immobilized acid ionic liquid [HCPpitch–Im–Pros][Tos] were 3.5 mmol/g and 3.0 mmol/g, and the BET specific surface areas were 520 m2/g and 380 m2/g, respectively. This strategy provides an easy approach to preparing highly stable and acid functionalized mesoporous catalysts. The immobilized acidic ionic liquid was used as a catalyst for the esterification of oleic acid and methanol to synthesize biodiesel. The results demonstrated that under the optimal conditions of an alcohol to acid molar ratio of 7:1, ionic liquid to oleic acid molar ratio of 0.12, and a reaction time of 3 h at atmospheric pressure, the yield of methyl oleate can reach up to 93%. Moreover, the catalyst was reused five times without the yield decreasing significantly. This study shows that [HCPpitch–Im–Pros][Tos] is a robust catalyst for the synthesis of biodiesel.
      Citation: Catalysts
      PubDate: 2019-11-15
      DOI: 10.3390/catal9110963
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 964: Photocatalytic Removal of Methyl Orange Azo
           Dye with Simultaneous Hydrogen Production Using Ru-modified ZnO
           Photocatalyst

    • Authors: Vaiano, Iervolino
      First page: 964
      Abstract: The aim of this work is to demonstrate the effectiveness of the photocatalytic process in the Methyl Orange azo dye degradation and simultaneous H2 production by using ZnO doped with ruthenium. Ru-modified ZnO photocatalysts were prepared by precipitation method and were characterized by different techniques (XRF, Raman, XRD, N2 adsorption at −196 °C, and UV–vis DRS). The experiments were carried out in a pyrex cylindrical reactor equipped with a nitrogen distributor device and irradiated by four UV lamps with the main wavelength emission at 365 nm. Different Ru amounts (from 0.10 to 0.50 mol%) were tested in order to establish the optimal amount of the metal to be used for the ZnO doping. The photocatalytic activity was evaluated both in terms of Methyl Orange removal and hydrogen production. The experimental results showed that the best activity, both in terms of H2 production and Methyl Orange degradation, was obtained with the Ru-modified ZnO photocatalyst at 0.25 mol% Ru loading. In particular, after four hours of UV irradiation time, the discoloration and mineralization degree were equal to 83% and 78%, with a simultaneous hydrogen production of 1216 µmol L−1. This result demonstrates the ability of the photocatalytic process to valorize a dye present in wastewater, managing to obtain a hydrogen production comparable with the data present in the literature today in the presence of other sacrificial substances.
      Citation: Catalysts
      PubDate: 2019-11-15
      DOI: 10.3390/catal9110964
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 965: Assessment of Degradation Behavior for
           Acetylsalicylic Acid Using a Plasma in Liquid Process

    • Authors: Hye-Jin Bang, Heon Lee, Young-Kwon Park, Hyung-Ho Ha, Young Hyun Yu, Byung-Joo Kim, Sang-Chul Jung
      First page: 965
      Abstract: Acetylsalicylic acid (ASA) is a pharmacologically active compound. In this study, ASA was decomposed effectively using a plasma in liquid phase process with hydrogen peroxide and TiO2 photocatalyst. Increasing the electrical power conditions (frequency, applied voltage, and pulse width) promoted plasma generation, which increased the rate of ASA decomposition. The added hydrogen peroxide increased the rate of ASA degradation, but injecting an excess decreased the degradation rate due to a scavenger effect. Although there was an initial increase in the decomposition efficiency by the addition of TiO2 powder, the addition of an excessive amount inhibited the generation of plasma and decreased the degradation rate. The simultaneous addition of H2O2 and TiO2 powder resulted in the highest degradation efficiency. We suggest that ASA is converted to salicylic acid through demethylation by hydroxyl radicals and is finally mineralized to carbon dioxide and water via 2,4-dihydroxy benzoic acid and low molecular acids.
      Citation: Catalysts
      PubDate: 2019-11-16
      DOI: 10.3390/catal9110965
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 966: Enhanced Performance of Immobilized
           Xylanase/Filter Paper-ase on a Magnetic Chitosan Support

    • Authors: Aldo Amaro-Reyes, Azariel Díaz-Hernández, Jorge Gracida, Blanca E. García-Almendárez, Monserrat Escamilla-García, Teresita Arredondo-Ochoa, Carlos Regalado
      First page: 966
      Abstract: Enzyme immobilization on different supports has emerged as an efficient and cost-effective tool to improve their stability and reuse capacity. This work aimed to produce a stable immobilized multienzymatic system of xylanase and filter paper-ase (FPase) onto magnetic chitosan using genipin as a cross-linking agent and to evaluate its biochemical properties and reuse capacity. A mixture of chitosan magnetic nanoparticles, xylanase, and FPase was covalently bonded using genipin. Immobilization yield and efficiency were quantified. The activity of free and immobilized enzymes was quantified at different values of pH, temperature, substrate concentration (Km and Vmax), and reuse cycles. The immobilization yield, immobilization efficiency, and activity recovery were 145.3% ± 3.06%, 14.8% ± 0.81%, and 21.5% ± 0.72%, respectively, measured as the total hydrolytic activity. Immobilization confers resistance to acidic/basic conditions and thermal stability compared to the free form. Immobilization improved 3.5-fold and 78-fold the catalytic efficiency (Kcat/Km) of the xylanase and filter paper-ase activities, while immobilized xylanase and FPase could be reused for 34 min and 43 min, respectively. Cross-linking significantly improved the biochemical properties of immobilized enzymes, combined with their simplicity of reuse due to the paramagnetic property of the support. Multienzyme immobilization technology is an important issue for industrial applications.
      Citation: Catalysts
      PubDate: 2019-11-16
      DOI: 10.3390/catal9110966
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 967: Second-Generation Manganese(III) Porphyrins
           Bearing 3,5-Dichloropyridyl Units: Innovative Homogeneous and
           Heterogeneous Catalysts for the Epoxidation of Alkenes

    • Authors: Neves, Rebelo, Faustino, Neves, Simões
      First page: 967
      Abstract: The synthesis, characterisation and homogeneous catalytic oxidation results of two manganese(III) porphyrins of the so-called second-generation of metalloporphyrin catalysts, containing one or four 3,5-dichloropyridyl substituents at the meso positions are reported for the first time. The catalytic efficiency of these novel manganese(III) porphyrins was evaluated in the oxidation of cyclooctene and styrene using aqueous hydrogen peroxide as the oxidant, under homogeneous conditions. High conversions were obtained in the presence of both catalysts, obtaining the corresponding epoxide as the major product. The asymmetric metalloporphyrin, chloro[5,10,15-tris(2,6-dichlorophenyl)-20-(3,5-dichloropyridin-4-yl)porphyrinate]manganese(III), CAT-4, evidences a similar activity to that obtained with the well-known and highly efficient second-generation metalloporphyrin catalyst, chloro[5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrinate]manganese(III), CAT-2. CAT-4 was covalently attached onto Merrifield resin and 3-bromopropylsilica supports. The solid materials obtained were characterized by several techniques including diffuse reflectance, UV—VIS spectrophotometry, SEM and XPS. The catalytic results for the oxidation of cyclooctene and styrene using the immobilized catalysts are also presented. The Merrifield-supported catalyst showed to be very efficient, leading to five catalytic cycles in the oxidation of cyclooctene, using tert-butyl hydroperoxide as the oxidant.
      Citation: Catalysts
      PubDate: 2019-11-16
      DOI: 10.3390/catal9110967
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 968: Ca-Doped CrOX/γ-Al2O3 Catalysts with
           Improved Dehydrogenation Performance for the Conversion of Isobutane to
           Isobutene

    • Authors: Guangjian Wang, Ning Song, Kai Lu, Wentai Wang, Liancheng Bing, Qinqin Zhang, Haitao Fu, Fang Wang, Dezhi Han
      First page: 968
      Abstract: The dehydrogenation of low-carbon alkane to obtain olefins is an effective way to meet the steadily increasing demand of these building blocks in chemical industry. In this study, Ca-doped CrOx/γ-Al2O3 catalysts were fabricated via a one-pot method by employing Cr(OH)3 as the precursor, and their catalytic performances were tested in the dehydrogenation of isobutane to isobutene (DITI) process. The prepared catalysts were intensively characterized by XRD, SEM, NH3-TPD, H2-TPR, low-temperature N2 adsorption–desorption, etc. These characterization results indicated that the doping of Ca into the CrOx/γ-Al2O3 catalysts could tune the acidity properties of the prepared catalysts and enhance the interaction between the active species and support. The Ca-doped CrOx/γ-Al2O3 catalysts, especially the Ca2-Cr/γ-Al2O3 catalyst with a Ca doping of 2 wt%, exhibited a superior catalytic performance in the DITI process in comparison with the undoped catalyst.
      Citation: Catalysts
      PubDate: 2019-11-16
      DOI: 10.3390/catal9110968
      Issue No: Vol. 9, No. 11 (2019)
       
  • Catalysts, Vol. 9, Pages 869: The Steric Effect in Green Benzylation of
           Arenes with Benzyl Alcohol Catalyzed by Hierarchical H-beta Zeolite

    • Authors: Xinyu Liu, Meihuan Lu, Xuan Wang, Juyou Lu, Jianxin Yang
      First page: 869
      Abstract: For decades the steric effect was still ambiguously understood in catalytic benzylation reactions of arenes with benzyl alcohol, which limited the green synthesis of phenylmethane derivates in industrial scale. This research applies a series of silica–alumina beta zeolites to systematically evaluate factors like catalyst porosity, reactants molecule size, and reaction temperature on catalytic benzylation. First, a suitable hierarchical beta zeolite catalyst was screened out by X-ray powder diffraction, N2 adsorption−desorption, and probe benzylation with p-xylene. In the following substrates expanding study, for a typical benzylation of benzene, it showed extraordinary performance among literature reported ones that the conversion was 98% while selectivity was 90% at 353 K only after 10 min. The steric effect of aromatics with different molecular sizes on benzylation was observed. The reaction activities of four different aromatics followed the order: benzene > toluene > p-xylene > mesitylene. Combined with macroscopic kinetic analysis, this comprehensive study points out for the first time that the nature of this steric effect was dominated by the relative adsorption efficiency of different guest aromatic molecules on the host zeolite surface.
      Citation: Catalysts
      PubDate: 2019-10-20
      DOI: 10.3390/catal9100869
      Issue No: Vol. 9, No. 10 (2019)
       
  • Catalysts, Vol. 9, Pages 870: Photocatalysts for Organics Degradation

    • Authors: Barbara Bonelli, Maela Manzoli, Francesca S. Freyria, Serena Esposito
      First page: 870
      Abstract: Organics degradation is one of the challenges of Advanced Oxidation Processes (AOPs), which are mainly employed for the removal of water and air pollutants [...]
      Citation: Catalysts
      PubDate: 2019-10-21
      DOI: 10.3390/catal9100870
      Issue No: Vol. 9, No. 10 (2019)
       
  • Catalysts, Vol. 9, Pages 871: Eco-Toxicological and Kinetic Evaluation of
           TiO2 and ZnO Nanophotocatalysts in Degradation of Organic Dye

    • Authors: Sajjad Khezrianjoo, Jechan Lee, Ki-Hyun Kim, Vanish Kumar
      First page: 871
      Abstract: In this study, the photocatalytic degradation of azo dye “Food Black 1” (FB1) was investigated using TiO2 and ZnO nanoparticles under ultraviolet (UV) light. The performances of the two photocatalysts were evaluated in terms of key parameters (e.g., decolorization, dearomatization, mineralization, and detoxification of dye) in relation to variables including pre-adsorption period, pH, and temperature. Under acidic conditions (pH 5), the ZnO catalyst underwent photocorrosion to increase the concentration of zinc ions in the system, thereby increasing the toxic properties of the treated effluent. In contrast, TiO2 efficiently catalyzed the degradation of the dye at pH 5 following the Langmuir–Hinshelwood (L–H) kinetic model. The overall results of this study indicate that the decolorization rate of TiO2 on the target dye was far superior to ZnO (i.e., by 1.5 times) at optimum catalyst loading under UV light.
      Citation: Catalysts
      PubDate: 2019-10-21
      DOI: 10.3390/catal9100871
      Issue No: Vol. 9, No. 10 (2019)
       
  • Catalysts, Vol. 9, Pages 872: Kinetics of Fischer–Tropsch Synthesis in a
           3-D Printed Stainless Steel Microreactor Using Different Mesoporous Silica
           Supported Co-Ru Catalysts

    • Authors: Mohammad, Bepari, Aravamudhan, Kuila
      First page: 872
      Abstract: Fischer–Tropsch (FT) synthesis was carried out in a 3D printed stainless steel (SS) microchannel microreactor using bimetallic Co-Ru catalysts on three different mesoporous silica supports. CoRu-MCM-41, CoRu-SBA-15, and CoRu-KIT-6 were synthesized using a one-pot hydrothermal method and characterized by Brunner–Emmett–Teller (BET), temperature programmed reduction (TPR), SEM-EDX, TEM, and X-ray photoelectron spectroscopy (XPS) techniques. The mesoporous catalysts show the long-range ordered structure as supported by BET and low-angle XRD studies. The TPR profiles of metal oxides with H2 varied significantly depending on the support. These catalysts were coated inside the microchannels using polyvinyl alcohol and kinetic performance was evaluated at three different temperatures, in the low-temperature FT regime (210–270 °C), at different Weight Hourly Space Velocity (WHSV) in the range of 3.15–25.2 kgcat.h/kmol using a syngas ratio of H2/CO = 2. The mesoporous supports have a significant effect on the FT kinetics and stability of the catalyst. The kinetic models (FT-3, FT-6), based on the Langmuir–Hinshelwood mechanism, were found to be statistically and physically relevant for FT synthesis using CoRu-MCM-41 and CoRu-KIT-6. The kinetic model equation (FT-2), derived using Eley–Rideal mechanism, is found to be relevant for CoRu-SBA-15 in the SS microchannel microreactor. CoRu-KIT-6 was found to be 2.5 times more active than Co-Ru-MCM-41 and slightly more active than CoRu-SBA-15, based on activation energy calculations. CoRu-KIT-6 was ~3 and ~1.5 times more stable than CoRu-SBA-15 and CoRu-MCM-41, respectively, based on CO conversion in the deactivation studies.
      Citation: Catalysts
      PubDate: 2019-10-21
      DOI: 10.3390/catal9100872
      Issue No: Vol. 9, No. 10 (2019)
       
  • Catalysts, Vol. 9, Pages 873: Biocatalytic Synthesis of Natural Green Leaf
           Volatiles Using the Lipoxygenase Metabolic Pathway

    • Authors: Sophie Vincenti, Magali Mariani, Jean-Christophe Alberti, Sabrina Jacopini, Virginie Brunini-Bronzini de Caraffa, Liliane Berti, Jacques Maury
      First page: 873
      Abstract: In higher plants, the lipoxygenase enzymatic pathway combined actions of several enzymes to convert lipid substrates into signaling and defense molecules called phytooxylipins including short chain volatile aldehydes, alcohols, and esters, known as green leaf volatiles (GLVs). GLVs are synthesized from C18:2 and C18:3 fatty acids that are oxygenated by lipoxygenase (LOX) to form corresponding hydroperoxides, then the action of hydroperoxide lyase (HPL) produces C6 or C9 aldehydes that can undergo isomerization, dehydrogenation, and esterification. GLVs are commonly used as flavors to confer a fresh green odor of vegetable to perfumes, cosmetics, and food products. Given the increasing demand in these natural flavors, biocatalytic processes using the LOX pathway reactions constitute an interesting application. Vegetable oils, chosen for their lipid profile are converted in natural GLVs with high added value. This review describes the enzymatic reactions of GLVs biosynthesis in the plant, as well as the structural and functional properties of the enzymes involved. The various stages of the biocatalytic production processes are approached from the lipid substrate to the corresponding aldehyde or alcoholic aromas, as well as the biotechnological improvements to enhance the production potential of the enzymatic catalysts.
      Citation: Catalysts
      PubDate: 2019-10-22
      DOI: 10.3390/catal9100873
      Issue No: Vol. 9, No. 10 (2019)
       
  • Catalysts, Vol. 9, Pages 874: Screening and Comparative Characterization
           of Microorganisms from Iranian Soil Samples Showing ω-Transaminase
           Activity toward a Plethora of Substrates

    • Authors: Najme Gord Noshahri, Jamshid Fooladi, Christoph Syldatk, Ulrike Engel, Majid M. Heravi, Mohammad Zare Mehrjerdi, Jens Rudat
      First page: 874
      Abstract: In this study, soil microorganisms from Iran were screened for ω-transaminase (ω-TA) activity based on growth on minimal media containing (rac)-α-methylbenzylamine (rac-α-MBA) as a sole nitrogen source. Then, for the selection of strains with high enzyme activity, a colorimetric o-xylylendiamine assay was conducted. The most promising strains were identified by 16S rDNA sequencing. Five microorganisms showing high ω-TA activity were subjected to determine optimal conditions for ω-TA activity, including pH, temperature, co-solvent, and the specificity of the ω-TA toward different amine donors and acceptors. Among the five screened microorganisms, Bacillus halotolerans turned out to be the most promising strain: Its cell-free extract showed a highly versatile amino donor spectrum toward aliphatic, aromatic chiral amines and a broad range of pH activity. Transaminase activity also exhibited excellent solvent tolerance, with maximum turnover in the presence of 30% (v/v) DMSO.
      Citation: Catalysts
      PubDate: 2019-10-22
      DOI: 10.3390/catal9100874
      Issue No: Vol. 9, No. 10 (2019)
       
 
 
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