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  Subjects -> CHEMISTRY (Total: 885 journals)
    - ANALYTICAL CHEMISTRY (55 journals)
    - CHEMISTRY (619 journals)
    - CRYSTALLOGRAPHY (21 journals)
    - ELECTROCHEMISTRY (28 journals)
    - INORGANIC CHEMISTRY (43 journals)
    - ORGANIC CHEMISTRY (48 journals)
    - PHYSICAL CHEMISTRY (71 journals)

CHEMISTRY (619 journals)                  1 2 3 4 | Last

Showing 1 - 200 of 735 Journals sorted alphabetically
2D Materials     Hybrid Journal   (Followers: 14)
Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement     Hybrid Journal   (Followers: 27)
ACS Catalysis     Hybrid Journal   (Followers: 44)
ACS Chemical Neuroscience     Hybrid Journal   (Followers: 22)
ACS Combinatorial Science     Hybrid Journal   (Followers: 23)
ACS Macro Letters     Hybrid Journal   (Followers: 26)
ACS Medicinal Chemistry Letters     Hybrid Journal   (Followers: 41)
ACS Nano     Hybrid Journal   (Followers: 295)
ACS Photonics     Hybrid Journal   (Followers: 14)
ACS Symposium Series     Full-text available via subscription  
ACS Synthetic Biology     Hybrid Journal   (Followers: 25)
Acta Chemica Iasi     Open Access   (Followers: 5)
Acta Chimica Slovaca     Open Access   (Followers: 2)
Acta Chimica Slovenica     Open Access   (Followers: 1)
Acta Chromatographica     Full-text available via subscription   (Followers: 9)
Acta Facultatis Medicae Naissensis     Open Access  
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 7)
Acta Scientifica Naturalis     Open Access   (Followers: 3)
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 8)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 9)
Adsorption Science & Technology     Open Access   (Followers: 6)
Advanced Functional Materials     Hybrid Journal   (Followers: 60)
Advanced Science Focus     Free   (Followers: 5)
Advances in Chemical Engineering and Science     Open Access   (Followers: 69)
Advances in Chemical Science     Open Access   (Followers: 18)
Advances in Chemistry     Open Access   (Followers: 22)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 19)
Advances in Drug Research     Full-text available via subscription   (Followers: 25)
Advances in Environmental Chemistry     Open Access   (Followers: 7)
Advances in Enzyme Research     Open Access   (Followers: 10)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 9)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 16)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 12)
Advances in Materials Physics and Chemistry     Open Access   (Followers: 26)
Advances in Nanoparticles     Open Access   (Followers: 15)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 17)
Advances in Polymer Science     Hybrid Journal   (Followers: 45)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 18)
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: 12)
African Journal of Bacteriology Research     Open Access  
African Journal of Chemical Education     Open Access   (Followers: 3)
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  
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 2)
AMB Express     Open Access   (Followers: 1)
Ambix     Hybrid Journal   (Followers: 3)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 67)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 21)
American Journal of Chemistry     Open Access   (Followers: 31)
American Journal of Plant Physiology     Open Access   (Followers: 11)
American Mineralogist     Hybrid Journal   (Followers: 15)
Analyst     Full-text available via subscription   (Followers: 38)
Angewandte Chemie     Hybrid Journal   (Followers: 171)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 255)
Annales UMCS, Chemia     Open Access   (Followers: 1)
Annals of Clinical Chemistry and Laboratory Medicine     Open Access   (Followers: 5)
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: 9)
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: 13)
Anti-Infective Agents     Hybrid Journal   (Followers: 3)
Antiviral Chemistry and Chemotherapy     Open Access   (Followers: 2)
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 9)
Applied Spectroscopy     Full-text available via subscription   (Followers: 24)
Applied Surface Science     Hybrid Journal   (Followers: 32)
Arabian Journal of Chemistry     Open Access   (Followers: 6)
ARKIVOC     Open Access   (Followers: 1)
Asian Journal of Biochemistry     Open Access   (Followers: 2)
Asian Journal of Chemistry and Pharmaceutical Sciences     Open Access  
Atomization and Sprays     Full-text available via subscription   (Followers: 4)
Australian Journal of Chemistry     Hybrid Journal   (Followers: 7)
Autophagy     Hybrid Journal   (Followers: 2)
Avances en Quimica     Open Access  
Biochemical Pharmacology     Hybrid Journal   (Followers: 10)
Biochemistry     Hybrid Journal   (Followers: 369)
Biochemistry Insights     Open Access   (Followers: 6)
Biochemistry Research International     Open Access   (Followers: 6)
BioChip Journal     Hybrid Journal  
Bioinorganic Chemistry and Applications     Open Access   (Followers: 10)
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: 22)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 11)
Biomedical Chromatography     Hybrid Journal   (Followers: 7)
Biomolecular NMR Assignments     Hybrid Journal   (Followers: 3)
BioNanoScience     Partially Free   (Followers: 5)
Bioorganic & Medicinal Chemistry     Hybrid Journal   (Followers: 134)
Bioorganic & Medicinal Chemistry Letters     Hybrid Journal   (Followers: 87)
Bioorganic Chemistry     Hybrid Journal   (Followers: 10)
Biopolymers     Hybrid Journal   (Followers: 18)
Biosensors     Open Access   (Followers: 2)
Biotechnic and Histochemistry     Hybrid Journal   (Followers: 1)
Bitácora Digital     Open Access  
Boletin de la Sociedad Chilena de Quimica     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: 24)
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: 10)
Canadian Mineralogist     Full-text available via subscription   (Followers: 6)
Carbohydrate Research     Hybrid Journal   (Followers: 26)
Carbon     Hybrid Journal   (Followers: 70)
Catalysis for Sustainable Energy     Open Access   (Followers: 8)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 7)
Catalysis Science and Technology     Free   (Followers: 8)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysts     Open Access   (Followers: 10)
Cellulose     Hybrid Journal   (Followers: 7)
Cereal Chemistry     Full-text available via subscription   (Followers: 4)
ChemBioEng Reviews     Full-text available via subscription   (Followers: 1)
ChemCatChem     Hybrid Journal   (Followers: 8)
Chemical and Engineering News     Free   (Followers: 22)
Chemical Bulletin of Kazakh National University     Open Access  
Chemical Communications     Full-text available via subscription   (Followers: 74)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 26)
Chemical Research in Chinese Universities     Hybrid Journal   (Followers: 3)
Chemical Research in Toxicology     Hybrid Journal   (Followers: 22)
Chemical Reviews     Hybrid Journal   (Followers: 197)
Chemical Science     Open Access   (Followers: 26)
Chemical Technology     Open Access   (Followers: 28)
Chemical Vapor Deposition     Hybrid Journal   (Followers: 5)
Chemie in Unserer Zeit     Hybrid Journal   (Followers: 57)
Chemie-Ingenieur-Technik (Cit)     Hybrid Journal   (Followers: 24)
ChemInform     Hybrid Journal   (Followers: 8)
Chemistry & Biodiversity     Hybrid Journal   (Followers: 7)
Chemistry & Biology     Full-text available via subscription   (Followers: 32)
Chemistry & Industry     Hybrid Journal   (Followers: 7)
Chemistry - A European Journal     Hybrid Journal   (Followers: 159)
Chemistry - An Asian Journal     Hybrid Journal   (Followers: 16)
Chemistry and Materials Research     Open Access   (Followers: 21)
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: 44)
Chemistry of Materials     Hybrid Journal   (Followers: 266)
Chemistry of Natural Compounds     Hybrid Journal   (Followers: 9)
Chemistry World     Full-text available via subscription   (Followers: 20)
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: 4)
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: 11)
Chromatographia     Hybrid Journal   (Followers: 24)
Chromatography     Open Access   (Followers: 2)
Chromatography Research International     Open Access   (Followers: 6)
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: 6)
Combinatorial Chemistry & High Throughput Screening     Hybrid Journal   (Followers: 4)
Combustion Science and Technology     Hybrid Journal   (Followers: 22)
Comments on Inorganic Chemistry: A Journal of Critical Discussion of the Current Literature     Hybrid Journal   (Followers: 2)
Communications Chemistry     Open Access  
Composite Interfaces     Hybrid Journal   (Followers: 7)
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: 1)
Computational and Theoretical Chemistry     Hybrid Journal   (Followers: 9)
Computational Biology and Chemistry     Hybrid Journal   (Followers: 12)
Computational Chemistry     Open Access   (Followers: 2)
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: 6)
Critical Reviews in Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 6)
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: 1)
Current Metabolomics     Hybrid Journal   (Followers: 5)
Current Microwave Chemistry     Hybrid Journal  
Current Opinion in Colloid & Interface Science     Hybrid Journal   (Followers: 9)
Current Opinion in Molecular Therapeutics     Full-text available via subscription   (Followers: 14)
Current Research in Chemistry     Open Access   (Followers: 9)
Current Science     Open Access   (Followers: 71)
Current Trends in Biotechnology and Chemical Research     Open Access   (Followers: 3)
Dalton Transactions     Full-text available via subscription   (Followers: 23)
Detection     Open Access   (Followers: 3)
Developments in Geochemistry     Full-text available via subscription   (Followers: 2)
Diamond and Related Materials     Hybrid Journal   (Followers: 12)
Dislocations in Solids     Full-text available via subscription  

        1 2 3 4 | Last

Journal Cover
Catalysts
Number of Followers: 10  

  This is an Open Access Journal Open Access journal
ISSN (Online) 2073-4344
Published by MDPI Homepage  [205 journals]
  • Catalysts, Vol. 8, Pages 359: Theoretical Calculations on the Mechanism of
           Enantioselective Copper(I)-Catalyzed Addition of Enynes to Ketones

    • Authors: Hanwei Li, Mingliang Luo, Guohong Tao, Song Qin
      First page: 359
      Abstract: Computational investigations on the bisphospholanoethane (BPE)-ligated Cu-catalyzed enantioselective addition of enynes to ketones were performed with the density functional theory (DFT) method. Two BPE-mesitylcopper (CuMes) catalysts, BPE-CuMes and (S,S)-Ph-BPE–CuMes, were employed to probe the reaction mechanism with the emphasis on stereoselectivity. The calculations on the BPE-CuMes system indicate that the active metallized enyne intermediate acts as the catalyst for the catalytic cycle. The catalytic cycle involves two steps: (1) ketone addition to the alkene moiety of the metallized enyne; and (2) metallization of the enyne followed by the release of product with the recovery of the active metallized enyne intermediate. The first step accounts for the distribution of the products, and therefore is the stereo-controlling step in chiral systems. In the chiral (S,S)-Ph-BPE–CuMes system, the steric hindrance is vital for the distribution of products and responsible for the stereoselectivity of this reaction. The steric hindrance between the phenyl ring of the two substrates and groups at the chiral centers in the ligand skeleton is identified as the original of the stereoselectivity for the titled reaction.
      Citation: Catalysts
      PubDate: 2018-08-28
      DOI: 10.3390/catal8090359
      Issue No: Vol. 8, No. 9 (2018)
       
  • Catalysts, Vol. 8, Pages 360: Effect of Surface Modifications of SBA-15
           with Aminosilanes and 12-Tungstophosphoric Acid on Catalytic Properties in
           Environmentally Friendly Esterification of Glycerol with Oleic Acid to
           Produce Monoolein

    • Authors: Kullatida Ratchadapiban, Piyasan Praserthdam, Duangamol Nuntasri Tungasmita, Chutima Tangku, Wipark Anutrasakda
      First page: 360
      Abstract: A series of protonated amino-functionalized SBA-15 materials was synthesized and tested as heterogeneous catalysts for the esterification of glycerol with oleic acid to produce monoolein. Mesoporous SBA-15 (S) was functionalized with three different aminosilanes: 3-aminopropyltriethoxysilane (N1); [3-(2-amino-ethylamino)propyltrimethoxysilane] (N2); and (3-trimethoxysilylpropyl) diethylenetriamine (N3), before being impregnated with 40 wt % 12-tungstophosphoric acid (HPW). The resulting nanocatalysts (S-Nx-HPW) were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), N2 adsorption-desorption, SEM equipped with energy dispersive X-ray spectroscopy (SEM-EDX), transmission electron microscopy (TEM), and elemental analysis techniques. The presence of components of the nanocatalysts and the preservation of the hexagonal structure of SBA-15 were confirmed. Using different functionalizing agents considerably affected the textural properties and acidity of the synthesized nanocatalysts, which helped to improve the catalytic performance. In particular, S-N2-HPW was more active and selective than other catalysts in this study, as well as than a number of other commercial acid catalysts, with 95.0% oleic acid conversion and 60.9% monoolein selectivity being obtained after five h of reaction at 160 °C using 2.5 wt % of catalyst loading and glycerol/oleic acid molar ratio of 4:1. Aminosilane functionalization also helped to increase the reusability of the catalysts to at least six cycles without considerable loss of activity through strong electrostatic interactions between HPW anions and the protonated amino-functionalized SBA-15 materials.
      Citation: Catalysts
      PubDate: 2018-08-28
      DOI: 10.3390/catal8090360
      Issue No: Vol. 8, No. 9 (2018)
       
  • Catalysts, Vol. 8, Pages 361: The Reduction Temperature Effect of
           Fe–Co/MgO Catalyst on Characteristics of Multi-Walled Carbon Nanotubes

    • Authors: Paul Kim, Cheol Jin Lee
      First page: 361
      Abstract: Diameters and crystallinity of multi-walled carbon nanotubes (MWCNTs) dependent on reduction temperature of the Fe–Co/MgO catalyst were investigated. MWCNTs were synthesized by catalytic chemical vapor depositing and the Fe–Co/MgO catalyst was fabricated by using a sol-gel method. According to Raman analysis, transmission electron microscopy and thermogravimetric analysis, the diameter distribution of MWCNTs was broadened with increasing reduction temperature of the Fe–Co/MgO catalyst and crystallinity was improved. The above results are attributed to an increased size and enhanced crystallinity of metal catalyst particles by increasing reduction temperature.
      Citation: Catalysts
      PubDate: 2018-08-28
      DOI: 10.3390/catal8090361
      Issue No: Vol. 8, No. 9 (2018)
       
  • Catalysts, Vol. 8, Pages 362: Two Complementary Synthetic Approaches to
           the Enantiomeric Forms of the Chiral Building Block
           (2,6,6-Trimethyltetrahydro-2H-pyran-2-yl)methanol: Application to the
           Stereospecific Preparation of the Natural Flavor Linaloyl Oxide

    • Authors: Serra, De Simeis
      First page: 362
      Abstract: The enantiomeric forms of the alcohol (2,6,6-trimethyltetrahydro-2H-pyran-2-yl)methanol are potential chiral building blocks for the stereoselective synthesis of different natural terpenes. Here, we describe their preparation by means of two different synthetic approaches. The first is based on the stereospecific (+)-10-camphorsulfonic acid (CSA)-catalyzed cyclization of (R)- and (S)-2-methyl-5-(2-methyloxiran-2-yl)pentan-2-ol, which were in turn synthesized from (R)- and (S)-linalool, respectively. The latter monoterpenes are easily available from the chiral pool, with different optical purity. As our synthesis makes use of the intermediate 2,6-dimethyloct-7-ene-2,6-diol, whose enantiopurity can be improved through fractional crystallization, we obtained (2,6,6-trimethyltetrahydro-2H-pyran-2-yl)methanol enantiomers in an almost enantiopure form. The second synthetic approach is based on the lipase-mediated resolution of the aforementioned tetrahydropyranyl alcohol, which was prepared in racemic form starting from the industrial intermediate, dehydrolinalool. In this work, we report a large-scale resolution procedure that exploits the opposite enantioselectivity of Novozym® 435 lipase and lipase AK in the acetylation reaction of (2,6,6-trimethyltetrahydro-2H-pyran-2-yl)methanol. The two enantiomeric forms of the latter alcohol were employed for the first stereoselective synthesis of both enantiomers of the flavor, linaloyl oxide (2,2,6-trimethyl-6-vinyltetrahydro-2H-pyran).
      Citation: Catalysts
      PubDate: 2018-08-28
      DOI: 10.3390/catal8090362
      Issue No: Vol. 8, No. 9 (2018)
       
  • Catalysts, Vol. 8, Pages 363: High CO Methanation Performance of
           Two-Dimensional Ni/MgAl Layered Double Oxide with Enhanced Oxygen
           Vacancies via Flash Nanoprecipitation

    • Authors: Mengjuan Zhang, Feng Yu, Jiangbing Li, Kai Chen, Yongbin Yao, Panpan Li, Mingyuan Zhu, Yulin Shi, Qiang Wang, Xuhong Guo
      First page: 363
      Abstract: As a methanation tool, two-dimensional (2D) carrier-loaded Ni has attracted the attention of many researchers. We successfully prepared 2D MgAl layered double oxides (LDO) carriers via flash nanoprecipitation (FNP). Compared to the LDO samples prepared by conventional co-precipitation (CP), the 2D MgAl-LDO (FNP) has more oxygen vacancies and more exposed active sites. The Ni/MgAl-LDO (FNP) catalyst demonstrates a CO conversion of 97%, a CH4 selectivity of 79.8%, a turnover frequency of 0.141 s−1, and a CH4 yield of 77.4% at 350 °C. The weight hourly space velocity was 20,000 mL∙g−1∙h−1 with a synthesis gas flow rate of 65 mL∙min−1, and a pressure of 1 atm. A control experiment used the CP method to prepare Ni/MgAl-LDO. This material exhibits a CO conversion of 81.1%, a CH4 selectively of 75.1%, a TOF of 0.118 s−1, and a CH4 yield of 61% at 450 °C. We think that this FNP method can be used for the preparation of more 2D LDO catalysts.
      Citation: Catalysts
      PubDate: 2018-08-29
      DOI: 10.3390/catal8090363
      Issue No: Vol. 8, No. 9 (2018)
       
  • Catalysts, Vol. 8, Pages 364: Synthesis of 1,5-Functionalized
           1,2,3-Triazoles Using Ionic Liquid/Iron(III) Chloride as an Efficient and
           Reusable Homogeneous Catalyst

    • Authors: Antonio De Nino, Pedro Merino, Vincenzo Algieri, Monica Nardi, Maria Luisa Di Gioia, Beatrice Russo, Matteo Antonio Tallarida, Loredana Maiuolo
      First page: 364
      Abstract: An efficient, eco-compatible, and very cheap method for the construction of triazoles via eliminative azide–olefin cycloaddition (EAOC) reaction has been developed by a catalytic system, IL/FeCl3, offering a highly regioselective approach to structurally diverse 1,5-disubstituted 1,2,3-triazoles in up to 95% yield. This strategy features the reuse of a catalytic system through simple operations. Mechanistic studies indicated that an asynchronous concerted dipolar cycloaddition–elimination process might be involved.
      Citation: Catalysts
      PubDate: 2018-08-29
      DOI: 10.3390/catal8090364
      Issue No: Vol. 8, No. 9 (2018)
       
  • Catalysts, Vol. 8, Pages 365: Valorization of Biomass Derived Terpene
           Compounds by Catalytic Amination

    • Authors: Irina L. Simakova, Andrey V. Simakov, Dmitry Yu. Murzin
      First page: 365
      Abstract: This review fills an apparent gap existing in the literature by providing an overview of the readily available terpenes and existing catalytic protocols for preparation of terpene-derived amines. To address the role of solid catalysts in amination of terpenes the same reactions with homogeneous counterparts are also discussed. Such catalysts can be considered as a benchmark, which solid catalysts should match. Although catalytic systems based on transition metal complexes have been developed for synthesis of amines to a larger extent, there is an apparent need to reduce the production costs. Subsequently, homogenous systems based on cheaper metals operating by nucleophilic substitution (e.g., Ni, Co, Cu, Fe) with a possibility of easy recycling, as well as metal nanoparticles (e.g., Pd, Au) supported on amphoteric oxides should be developed. These catalysts will allow synthesis of amine derivatives of terpenes which have a broad range of applications as specialty chemicals (e.g., pesticides, surfactants, etc.) and pharmaceuticals. The review will be useful in selection and design of appropriate solid materials with tailored properties as efficient catalysts for amination of terpenes.
      Citation: Catalysts
      PubDate: 2018-08-29
      DOI: 10.3390/catal8090365
      Issue No: Vol. 8, No. 9 (2018)
       
  • Catalysts, Vol. 8, Pages 366: Carbon Self-Doped Carbon Nitride Nanosheets
           with Enhanced Visible-Light Photocatalytic Hydrogen Production

    • Authors: Hongwei Wang, Guiqing Huang, Zhiwei Chen, Weibing Li
      First page: 366
      Abstract: In this study, we prepared carbon self-doped carbon nitride nanosheets through a glucose synergic co-condensation method. In the carbon self-doped structure, the N atoms in the triazine rings were substituted by C atoms, resulting in enhanced visible-light photocatalytic hydrogen production, which is three-times higher than that of bulk carbon nitride. The enhanced photocatalytic hydrogen production was attributed to the higher charge-carrier transfer rate and widened light absorption range of the carbon nitride nanosheets after carbon self-doping. Thus, this work highlights the importance of carbon self-doping for improving the photocatalytic performance. Meanwhile, it provides a feasible method for the preparation of carbon self-doped carbon nitride without destroying the 2D conjugated backbone structures.
      Citation: Catalysts
      PubDate: 2018-08-29
      DOI: 10.3390/catal8090366
      Issue No: Vol. 8, No. 9 (2018)
       
  • Catalysts, Vol. 8, Pages 367: Improving Interfacial Charge-Transfer
           Transitions in Nb-Doped TiO2 Electrodes with
           7,7,8,8-Tetracyanoquinodimethane

    • Authors: Reo Eguchi, Yuya Takekuma, Tsuyoshi Ochiai, Morio Nagata
      First page: 367
      Abstract: Interfacial charge-transfer (ICT) transitions involved in charge-separation mechanisms are expected to enable efficient photovoltaic conversions through one-step charge-separation processes. With this in mind, the charge-transfer complex fabricated from TiO2 nanoparticles and 7,7,8,8-tetracyanoquinodimethane (TCNQ) has been applied to dye-sensitized solar cells. However, rapid carrier recombination from the conduction band of TiO2 to the highest occupied molecular orbital (HOMO) of TCNQ remains a major issue for this complex. In this study, to inhibit surface-complex recombinations, we prepared Nb-doped TiO2 nanoparticles with different atomic ratios for enhanced electron transport. To investigate the effects of doping on electron injection through ICT transitions, these materials were examined as photoelectrodes. When TiO2 was doped with 1.5 mol % Nb, the Fermi level of the TiO2 electrode shifted toward the conduction band minimum, which improved electron back-contact toward the HOMO of TCNQ. The enhancement in electron transport led to increases in both short circuit current and open circuit voltage, resulting in a slight (1.1% to 1.3%) improvement in photovoltaic conversion efficiency compared to undoped TiO2. Such control of electron transport within the photoelectrode is attributed to improvements in electron injection through ICT transitions.
      Citation: Catalysts
      PubDate: 2018-08-30
      DOI: 10.3390/catal8090367
      Issue No: Vol. 8, No. 9 (2018)
       
  • Catalysts, Vol. 8, Pages 368: Metal–Organic Frameworks-Based
           Catalysts for Biomass Processing

    • Authors: Vera I. Isaeva, Oleg M. Nefedov, Leonid M. Kustov
      First page: 368
      Abstract: : Currently, metal–organic frame works (MOFs) as novel hybrid nanoporous materials are a top research interest, including endeavors in heterogeneous catalysis. MOF materials are promising heterogeneous catalytic systems due to their unique characteristics, such as a highly ordered structure, a record high surface area and a compositional diversity, which can be precisely tailored. Very recently, these metal-organic matrices have been proven as promising catalysts for biomass conversion into value-added products. The relevant publications show that the structure of MOFs can contribute essentially to the advanced catalytic performance in processes of biomass refining. This review aims at the consideration of the different ways for the rational design of MOF catalysts for biomass processing. The particular characteristics and peculiarities of the behavior of different MOF based catalytic systems including hybrid nanomaterials and composites will be also discussed by illustrating their outstanding performance with appropriate examples relevant to biomass catalytic processing.
      Citation: Catalysts
      PubDate: 2018-08-31
      DOI: 10.3390/catal8090368
      Issue No: Vol. 8, No. 9 (2018)
       
  • Catalysts, Vol. 8, Pages 369: Efficient Physisorption of Candida
           Antarctica Lipase B on Polypropylene Beads and Application for Polyester
           Synthesis

    • Authors: Simone Weinberger, Alessandro Pellis, James W. Comerford, Thomas J. Farmer, Georg M. Guebitz
      First page: 369
      Abstract: In the present work, Candida antarctica lipase B (CaLB) was adsorbed onto polypropylene beads using different reaction conditions, in order to investigate their influence on the immobilization process and the enzyme activity of the preparations in polymerization reactions. In general, lower salt concentrations were more favorable for the binding of enzyme to the carrier. Polymerisation of dimethyl adipate (DMA) and 1,4-butanediol (BDO) was investigated in thin-film systems at 70 °C and at both atmosphere pressure (1000 mbar) and 70 mbar. Conversion rates and molecular masses of the reaction products were compared with reactions catalyzed by CaLB in its commercially available form, known as Novozym 435 (CaLB immobilized on macroporous acrylic resin). The best results according to molecular weight and monomer conversion after 24 h reaction time were obtained with CaLB immobilized in 0.1 M Na2HPO4\NaH2PO4 buffer at pH 8, producing polyesters with 4 kDa at conversion rates of 96% under low pressure conditions. The stability of this preparation was studied in a simulated continuous polymerization process at 70 °C, 70 mbar for 4 h reaction time. The data of this continuous polymerizations show that the preparation produces lower molecular weights at lower conversion rates, but is comparable to the commercial enzyme concerning stability for 10 cycles. However, after 24 h reaction time, using our optimum preparation, higher molecular weight polyesters (4 kDa versus 3.1 kDa) were obtained when compared to Novozym 435.
      Citation: Catalysts
      PubDate: 2018-08-31
      DOI: 10.3390/catal8090369
      Issue No: Vol. 8, No. 9 (2018)
       
  • Catalysts, Vol. 8, Pages 370: Statistically Guided Synthesis of MoV-Based
           Mixed-Oxide Catalysts for Ethane Partial Oxidation

    • Authors: Juan D. Jimenez, Kathleen Mingle, Teeraya Bureerug, Cun Wen, Jochen Lauterbach
      First page: 370
      Abstract: The catalytic performance of Mo8V2Nb1-based mixed-oxide catalysts for ethane partial oxidation is highly sensitive to the doping of elements with redox and acid functionality. Specifically, control over product distributions to ethylene and acetic acid can be afforded via the specific pairing of redox elements (Pd, Ni, Ti) and acid elements (K, Cs, Te) and the levels at which these elements are doped. The redox element, acid element, redox/acid ratio, and dopant/host ratio were investigated using a three-level, four-factor factorial screening design to establish relationships between catalyst composition, structure, and product distribution for ethane partial oxidation. Results show that the balance between redox and acid functionality and overall dopant level is important for maximizing the formation of each product while maintaining the structural integrity of the host metal oxide. Overall, ethylene yield was maximized for a Mo8V2Nb1Ni0.0025Te0.5 composition, while acetic acid yield was maximized for a Mo8V2Nb1Ti0.005Te1 catalyst.
      Citation: Catalysts
      PubDate: 2018-09-02
      DOI: 10.3390/catal8090370
      Issue No: Vol. 8, No. 9 (2018)
       
  • Catalysts, Vol. 8, Pages 371: Performance of an Auto-Reduced Nickel
           Catalyst for Auto-Thermal Reforming of Dodecane

    • Authors: Seong Bin Jo, Dong Geon Ju, Suk Yong Jung, Dong Su Ha, Ho Jin Chae, Soo Chool Lee, Jae Chang Kim
      First page: 371
      Abstract: To investigate the catalytic performance of diesel reforming catalysts for production of hydrogen gas, Ni-Al catalyst was prepared by the polymer-modified incipient method (NA10-PM). NA10-PM showed excellent catalytic performance and economic feasibility in the auto-thermal reforming reaction, compared to other commercially available catalysts. In particular, auto-reduced NA10-PM showed higher dodecane conversion and similar selectivity at 750 °C compared to H2-reduced NA10-PM. X-ray diffraction (XRD) studies showed that the fresh state of NA10-PM initially automatically reduced by product gases through thermal decomposition of dodecane, and then NiAl2O4 was completely reduced to metallic nickel by the CO and H2 gases produced during the reaction. Additionally, catalytic performance of auto-reduced NA10-PM were investigated at varying steam/carbon molar ratio (S/C) and oxygen/carbon molar ratio (O2/C) in order to determine the optimum conditions of the auto-thermal reforming reaction. The conversion of dodecane over auto-reduced NA10-PM catalyst was remarkable (93%) and increased during the reaction, under conditions of S/C = 1.23, O2/C = 0.25, and gas hourly space velocity of 12,000 h−1 at 750 °C. The results of this study demonstrated that the auto-reduced NA10-PM catalyst was applied successfully for auto-thermal reforming of dodecane.
      Citation: Catalysts
      PubDate: 2018-09-03
      DOI: 10.3390/catal8090371
      Issue No: Vol. 8, No. 9 (2018)
       
  • Catalysts, Vol. 8, Pages 372: Hydrogen Production from Chemical Looping
           Steam Reforming of Ethanol over Perovskite-Type Oxygen Carriers with
           Bimetallic Co and Ni B-Site Substitution

    • Authors: Lin Li, Bo Jiang, Zhehao Sun, Qian Zhang, Duyu Li, Dawei Tang
      First page: 372
      Abstract: This paper describes the synthesis of a series of La1.4Sr0.6Ni1−xCoxO4 perovskite OCs using co-precipitation method by employing Co and Ni as the B-site components of perovskite and the synergetic effect of Co doping on chemical looping reforming of ethanol. A variety of techniques including N2 adsorption-desorption, X-ray diffraction (XRD), transmission electron microscopy (TEM) and H2 temperature-programmed reduction (TPR) were employed to investigate the physicochemical properties of the fresh and used OCs. The activity and stability in chemical looping reforming were studied in a fixed bed reactor at 600 °C and a S/C ratio of three. The synergetic effect between Ni and Co was able to enhance the catalytic activity and improve the stability of perovskite OCs. La1.4Sr0.6Ni0.6Co0.4O4 showed an average ethanol conversion of 92.4% and an average CO2/CO ratio of 5.4 in a 30-cycle stability test. Significantly, the H2 yield and purity reached 11 wt.% and 73%, respectively. The Co doping was able to significantly improve the self-regeneration capability due to the increase in the number of oxygen vacancies in the perovskite lattice, thereby enhancing the sintering resistance. Moreover, Co promotion also contributes to the improved WGS activity.
      Citation: Catalysts
      PubDate: 2018-09-04
      DOI: 10.3390/catal8090372
      Issue No: Vol. 8, No. 9 (2018)
       
  • Catalysts, Vol. 8, Pages 373: Value-Added Products from Urea Glycerolysis
           Using a Heterogeneous Biosolids-Based Catalyst

    • Authors: Mattia Bartoli, Chengyong Zhu, Michael Chae, David C. Bressler
      First page: 373
      Abstract: Although thermal hydrolysis of digested biosolids is an extremely promising strategy for wastewater management, the process economics are prohibitive. Here, a biosolids-based material generated through thermal hydrolysis was used as a catalyst for urea glycerolysis performed under several conditions. The catalytic system showed remarkable activity, reaching conversion values of up to 70.8 ± 0.9% after six hours, at 140 °C using a catalyst/glycerol weight ratio of 9% and an air stream to remove NH3 formed during the process. Temperature played the most substantial role among reaction parameters; increasing temperature from 100 °C to 140 °C improved conversion by 35% and glycidol selectivity by 22%. Furthermore, the catalyst retained good activity even after the fourth catalytic run (conversion rate of 56.4 ± 1.3%) with only a slight decrease in glycidol selectivity. Thus, the use of a biosolids-based catalyst may facilitate conversion of various glycerol sources (i.e., byproduct streams from biodiesel production) into value-added products such as glycidol, and may also improve the economic feasibility of using thermal hydrolysis for treatment of biosolids.
      Citation: Catalysts
      PubDate: 2018-09-04
      DOI: 10.3390/catal8090373
      Issue No: Vol. 8, No. 9 (2018)
       
  • Catalysts, Vol. 8, Pages 374: Enhancement Photocatalytic Activity of the
           Heterojunction of Two-Dimensional Hybrid Semiconductors ZnO/V2O5

    • Authors: Juan Aliaga, Nasla Cifuentes, Guillermo González, Clivia Sotomayor-Torres, Eglantina Benavente
      First page: 374
      Abstract: In this work, we report the fabrication of the new heterojunction of two 2D hybrid layered semiconductors—ZnO (stearic acid)/V2O5 (hexadecylamine)—and its behavior in the degradation of aqueous methylene blue under visible light irradiation. The optimal photocatalyst efficiency, reached at a ZnO (stearic acid)/V2O5 (hexadecylamine) ratio of 1:0.25, results in being six times higher than that of pristine zinc oxide. Reusability test shows that after three photocatalysis cycles, no significant changes in either the dye degradation efficiency loss, nor the photocatalyst structure, occur. Visible light photocatalytic performance observed indicates there is synergetic effect between both 2D nanocomposites used in the heterojunction. The visible light absorption enhancement promoted by the narrower bandgap V2O5 based components; an increased photo generated charge separation favored by extensive interface area; and abundance of hydrophobic sites for dye adsorption appear as probable causes of the improved photocatalytic efficiency in this hybrid semiconductors heterojunction. Estimated band-edge positions for both conduction and valence band of semiconductors, together with experiments using specific radical scavengers, allow a plausible photodegradation mechanism.
      Citation: Catalysts
      PubDate: 2018-09-04
      DOI: 10.3390/catal8090374
      Issue No: Vol. 8, No. 9 (2018)
       
  • Catalysts, Vol. 8, Pages 375: Ce and Zr Modified WO3-TiO2 Catalysts for
           Selective Catalytic Reduction of NOx by NH3

    • Authors: Wenyi Zhao, Zhaoqiang Li, Yan Wang, Rongrong Fan, Cheng Zhang, Yu Wang, Xin Guo, Rong Wang, Shule Zhang
      First page: 375
      Abstract: A series of Ce and/or Zr modified WO3-TiO2 catalysts were synthesized by the impregnation method, which were employed for NH3-SCR reaction. The T50 contour lines of NOx were used to quickly optimize catalyst composition, the Ce20Zr12.5WTi catalyst was considered to be the optimization result, and also exhibited excellent NH3-SCR activity and thermal stability with broad operation temperature window, which is a very promising catalyst for NOx abatement from diesel engine exhaust. The excellent catalytic performance is associated with the formation of Ce-Zr solid solution. The introduction of Zr to CeWTi catalyst facilitated the redox of Ce4+/Ce3+ and the formation of more acid sites, more Ce3+ ions, more oxygen vacancies, larger quantities of surface adsorbed oxygen species and NH3, which were beneficial for the excellent selective catalytic reduction (SCR) performance.
      Citation: Catalysts
      PubDate: 2018-09-05
      DOI: 10.3390/catal8090375
      Issue No: Vol. 8, No. 9 (2018)
       
  • Catalysts, Vol. 8, Pages 376: Synthesis of High Crystalline TiO2
           Nanoparticles on a Polymer Membrane to Degrade Pollutants from Water

    • Authors: Kristina Fischer, Paulina Schulz, Igor Atanasov, Amira Abdul Latif, Isabell Thomas, Mathias Kühnert, Andrea Prager, Jan Griebel, Agnes Schulze
      First page: 376
      Abstract: Titanium dioxide (TiO2) is described as an established material to remove pollutants from water. However, TiO2 is still not applied on a large scale due to issues concerning, for example, the form of use or low photocatalytic activity. We present an easily upscalable method to synthesize high active TiO2 nanoparticles on a polyethersulfone microfiltration membrane to remove pollutants in a continuous way. For this purpose, titanium(IV) isopropoxide was mixed with water and hydrochloric acid and treated up to 210 °C. After cooling, the membrane was simply dip-coated into the TiO2 nanoparticle dispersion. Standard characterization was undertaken (i.e., X-ray powder diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, water permeance, contact angle). Degradation of carbamazepine and methylene blue was executed. By increasing synthesis temperature crystallinity and photocatalytic activity elevates. Both ultrasound modification of nanoparticles and membrane pre-modification with carboxyl groups led to fine distribution of nanoparticles. The ultrasound-treated nanoparticles gave the highest photocatalytic activity in degrading carbamazepine and showed no decrease in degradation after nine times of repetition. The TiO2 nanoparticles were strongly bound to the membrane. Photocatalytic TiO2 nanoparticles with high activity were synthesized. The innovative method enables a fast and easy nanoparticle production, which could enable the use in large-scale water cleaning.
      Citation: Catalysts
      PubDate: 2018-09-05
      DOI: 10.3390/catal8090376
      Issue No: Vol. 8, No. 9 (2018)
       
  • Catalysts, Vol. 8, Pages 377: Optimization and Tunability of 2D Graphene
           and 1D Carbon Nanotube Electrocatalysts Structure for PEM Fuel Cells

    • Authors: Emeline Remy, Yohann. R. J. Thomas, Laure Guetaz, Frédéric Fouda-Onana, Pierre-André Jacques, Marie Heitzmann
      First page: 377
      Abstract: In this work, N-doped Multi-Walled Carbon Nanotubes (MWCNTs) and Few Graphene Layers (FGLs) have been functionalized with platinum nanoparticles using two methods starting with hexachloroplatinic acid as precursor: (i) ethylene glycol (EG) reduction and (ii) impregnation followed by reduction in hydrogen atmosphere. Morphological scanning transmission electron microscopy (STEM) analyses showed a homogenous dispersion of metal particles with narrow-size distribution onto both carbon supports (Pt/C loadings between 30 wt % and 40 wt %). Electrocatalytic properties of the as-synthetized catalysts toward the Oxygen Reduction Reaction (ORR) was evaluated in aqueous electrolyte using a three electrodes electrochemical cell by cyclic voltammetry (CV) in rotating disk electrode (RDE). It is shown that a mixture of Pt supported on MWCNT and FGLs allows to enhance both the electrochemical surface area and the activity of the catalyst layer. Ageing tests performed on that optimized active layer showed higher stability than conventional Pt/C.
      Citation: Catalysts
      PubDate: 2018-09-05
      DOI: 10.3390/catal8090377
      Issue No: Vol. 8, No. 9 (2018)
       
  • Catalysts, Vol. 8, Pages 378: The Preparation of Pd/Foam-Ni Electrode and
           Its Electrocatalytic Hydrodechlorination for Monochlorophenol Isomers

    • Authors: Junjing Li, Huan Wang, Liang Wang, Chang Ma, Cong Luan, Bin Zhao, Zhaohui Zhang, Hongwei Zhang, Xiuwen Cheng, Junliang Liu
      First page: 378
      Abstract: Noble metal palladium modified foamed nickel electrode (Pd/foam-Ni) was prepared by electrodeposition method. The fabricated electrode showed better catalytic performance than the Pd/foam-Ni prepared by conventional electroless deposition. The catalysts were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). Electrocatalytic activity of the Pd/Ni was studied for the hydrodechlorination of monochlorophenol isomers. The Pd/Ni exhibited good catalytic activity for 3-chlorophenol (3-CP). Complete decomposition of chlorophenol isomers could be achieved within 2 h, and the hydrodechlorination process conformed to the pseudo-first-order kinetic model. It showed a supreme stability after recycling for 5 times. The Pd/Ni exhibited a promising application prospect with high effectiveness and low Pd loading.
      Citation: Catalysts
      PubDate: 2018-09-05
      DOI: 10.3390/catal8090378
      Issue No: Vol. 8, No. 9 (2018)
       
  • Catalysts, Vol. 8, Pages 379: Recent Advances in the Direct Synthesis of
           Hydrogen Peroxide Using Chemical Catalysis—A Review

    • Authors: Sumanth Ranganathan, Volker Sieber
      First page: 379
      Abstract: Hydrogen peroxide is an important chemical of increasing demand in today’s world. Currently, the anthraquinone autoxidation process dominates the industrial production of hydrogen peroxide. Herein, hydrogen and oxygen are reacted indirectly in the presence of quinones to yield hydrogen peroxide. Owing to the complexity and multi-step nature of the process, it is advantageous to replace the process with an easier and straightforward one. The direct synthesis of hydrogen peroxide from its constituent reagents is an effective and clean route to achieve this goal. Factors such as water formation due to thermodynamics, explosion risk, and the stability of the hydrogen peroxide produced hinder the applicability of this process at an industrial level. Currently, the catalysis for the direct synthesis reaction is palladium based and the research into finding an effective and active catalyst has been ongoing for more than a century now. Palladium in its pure form, or alloyed with certain metals, are some of the new generation of catalysts that are extensively researched. Additionally, to prevent the decomposition of hydrogen peroxide to water, the process is stabilized by adding certain promoters such as mineral acids and halides. A major part of today’s research in this field focusses on the reactor and the mode of operation required for synthesizing hydrogen peroxide. The emergence of microreactor technology has helped in setting up this synthesis in a continuous mode, which could possibly replace the anthraquinone process in the near future. This review will focus on the recent findings of the scientific community in terms of reaction engineering, catalyst and reactor design in the direct synthesis of hydrogen peroxide.
      Citation: Catalysts
      PubDate: 2018-09-05
      DOI: 10.3390/catal8090379
      Issue No: Vol. 8, No. 9 (2018)
       
  • Catalysts, Vol. 8, Pages 380: High Active and Selective Ni/CeO2–Al2O3
           and Pd–Ni/CeO2–Al2O3 Catalysts for Oxy-Steam Reforming of Methanol

    • Authors: Pawel Mierczynski, Agnieszka Mierczynska, Radoslaw Ciesielski, Magdalena Mosinska, Magdalena Nowosielska, Agnieszka Czylkowska, Waldemar Maniukiewicz, Malgorzata I. Szynkowska, Krasimir Vasilev
      First page: 380
      Abstract: Herein, we report monometallic Ni and bimetallic Pd–Ni catalysts supported on CeO2–Al2O3 binary oxide which are highly active and selective in oxy-steam reforming of methanol (OSRM). Monometallic and bimetallic supported catalysts were prepared by an impregnation method. The physicochemical properties of the catalytic systems were investigated using a range of methods such as: Brunauer–Emmett–Teller (BET), X-ray Powder Diffraction (XRD), Temperature-programmed reduction (TPR–H2), Temperature-programmed desorption (TPD–NH3), X-ray photoelectron spectroscopy (XPS) and Scanning Electron Microscope equipped with an energy dispersive spectrometer (SEM–EDS). We demonstrate that the addition of palladium facilitates the reduction of nickel catalysts. The activity tests performed for all catalysts confirmed the promotion effect of palladium on the catalytic activity of nickel catalyst and their selectivity towards hydrogen production. Both nickel and bimetallic palladium–nickel supported catalysts showed excellent stability during the reaction. The reported catalytic systems are valuable to make advances in the field of fuel cell technology.
      Citation: Catalysts
      PubDate: 2018-09-06
      DOI: 10.3390/catal8090380
      Issue No: Vol. 8, No. 9 (2018)
       
  • Catalysts, Vol. 8, Pages 381: Theoretical Study on the Hydrogenation
           Mechanisms of Model Compounds of Heavy Oil in a Plasma-Driven Catalytic
           System

    • Authors: Haigang Hao, Pengfei Lian, Juhui Gong, Rui Gao
      First page: 381
      Abstract: Heavy oil will likely dominate the future energy market. Nevertheless, processing heavy oils using conventional technologies has to face the problems of high hydrogen partial pressure and catalyst deactivation. Our previous work reported a novel method to upgrade heavy oil using hydrogen non-thermal plasma under atmospheric pressure without a catalyst. However, the plasma-driven catalytic hydrogenation mechanism is still ambiguous. In this work, we investigated the intrinsic mechanism of hydrogenating heavy oil in a plasma-driven catalytic system based on density functional theory (DFT) calculations. Two model compounds, toluene and 4-ethyltoluene have been chosen to represent heavy oil, respectively; a hydrogen atom and ethyl radical have been chosen to represent the high reactivity species generated by plasma, respectively. DFT study results indicate that toluene is easily hydrogenated by hydrogen atoms, but hard to hydrocrack into benzene and methane; small radicals, like ethyl radicals, are prone to attach to the carbon atoms in aromatic rings, which is interpreted as the reason for the increased substitution index of trap oil. The present work investigated the hydrogenation mechanism of heavy oil in a plasma-driven catalytic system, both thermodynamically and kinetically.
      Citation: Catalysts
      PubDate: 2018-09-07
      DOI: 10.3390/catal8090381
      Issue No: Vol. 8, No. 9 (2018)
       
  • Catalysts, Vol. 8, Pages 382: Modeling the OEC with Two New Biomimetic
           Models: Preparations, Structural Characterization, and Water Photolysis
           Studies of a Ba–Mn Box Type Complex and a Mn4N6 Planar-Diamond Cluster

    • Authors: Lara Rouco, M. Isabel Fernández-García, Rosa Pedrido, Luis M. Botana, David Esteban-Gómez, Carlos Platas-Iglesias, Marcelino Maneiro
      First page: 382
      Abstract: The oxygen-evolving complex (OEC) is the native enzyme that catalyzes the oxidation of water in natural photosynthesis. Two new classes of manganese cluster complexes of formula Ba2Mn2L12(H3L1)2(CH3OH)4 1 and Mn4L26Cl2 2 were prepared (H4L1 = N,N′-(ethane-1,2-diyl)bis(2-hydroxybenzamide); L2 = methyl picolinimidate) and characterized by standard techniques including microanalysis, IR spectroscopy, ESI spectrometry, and magnetic susceptibility measurements. X-ray diffraction studies of these complexes revealed (i) a box-type structure for 1 formed by two redox-active manganese(III) ions and two barium(II) ions connected by two bridging bisamido-bisphenoxy ligand molecules; and (ii) a planar-diamond array for Mn4N6 cluster 2 where the picolinimidates act as chelating ligands through the two nitrogen atoms. The ability of 1 and 2 to split water has been studied by means of water photolysis experiments. In these experiments, the oxygen evolution was measured in aqueous media in the presence of p-benzoquinone (acting as the hydrogen acceptor), the reduction of which was followed by UV-spectroscopy. The relevant photolytic activity found for 1 is in contrast to the inactivity of 2 in the photolytic experiments. This different behavior is discussed on the basis of the structure of the biomimetic models and the proposed reaction mechanism for this process supported by DFT calculations.
      Citation: Catalysts
      PubDate: 2018-09-07
      DOI: 10.3390/catal8090382
      Issue No: Vol. 8, No. 9 (2018)
       
  • Catalysts, Vol. 8, Pages 383: Two Possible Side Reaction Pathways during
           Furanic Etherification

    • Authors: Wenting Fang, Hualei Hu, Zhongsen Ma, Lei Wang, Yajie Zhang
      First page: 383
      Abstract: The revealing mechanism of side reactions is crucial for obtaining theoretical yield in industrialization when 2,5-bis(methoxymethyl)furan (BMMF) yield is above 95%. By-products catalyzed by the conventional ZSM-5 (C-ZSM-5) and hierarchical porous ZSM-5 (HP-ZSM-5) catalytic systems were different, and some key by-products were identified. Thus, possible pathways were proposed, which helps to further improve BMMF selectivity. Additionally, HP-ZSM-5 exhibited quicker reaction rate, higher BMMF yield and selectivity, and slower deactivation process. The relatively weak acidity of HP-ZSM-5 suppresses the ring-opening reaction and subsequent side reactions, and introduction of mesopores improves mass transport and slightly increases hydration of 2,5-bis(hydroxymethyl)furan (BHMF).
      Citation: Catalysts
      PubDate: 2018-09-08
      DOI: 10.3390/catal8090383
      Issue No: Vol. 8, No. 9 (2018)
       
  • Catalysts, Vol. 8, Pages 384: NOx Removal by Selective Catalytic Reduction
           with Ammonia over a Hydrotalcite-Derived NiFe Mixed Oxide

    • Authors: Ruonan Wang, Xu Wu, Chunlei Zou, Xiaojian Li, Yali Du
      First page: 384
      Abstract: A series of NiFe mixed oxide catalysts were prepared via calcining hydrotalcite-like precursors for the selective catalytic reduction of nitrogen oxides (NOx) with NH3 (NH3-SCR). Multiple characterizations revealed that catalytic performance was highly dependent on the phase composition, which was vulnerable to the calcination temperature. The MOx phase (M = Ni or Fe) formed at a lower calcination temperature would induce more favorable contents of Fe2+ and Ni3+ and as a result contribute to the better redox capacity and low-temperature activity. In comparison, NiFe2O4 phase emerged at a higher calcination temperature, which was expected to generate more Fe species on the surface and lead to a stable structure, better high-temperature activity, preferable SO2 resistance, and catalytic stability. The optimum NiFe-500 catalyst incorporated the above virtues and afforded excellent denitration (DeNOx) activity (over 85% NOx conversion with nearly 98% N2 selectivity in the region of 210–360 °C), superior SO2 resistance, and catalytic stability.
      Citation: Catalysts
      PubDate: 2018-09-08
      DOI: 10.3390/catal8090384
      Issue No: Vol. 8, No. 9 (2018)
       
  • Catalysts, Vol. 8, Pages 385: Toward the Sustainable Synthesis of
           Propanols from Renewable Glycerol over MoO3-Al2O3 Supported Palladium
           Catalysts

    • Authors: Shanthi Samudrala, Sankar Bhattacharya
      First page: 385
      Abstract: The catalytic conversion of glycerol to value-added propanols is a promising synthetic route that holds the potential to overcome the glycerol oversupply from the biodiesel industry. In this study, selective hydrogenolysis of 10 wt% aqueous bio-glycerol to 1-propanol and 2-propanol was performed in the vapor phase, fixed-bed reactor by using environmentally friendly bifunctional Pd/MoO3-Al2O3 catalysts prepared by wetness impregnation method. The physicochemical properties of these catalysts were derived from various techniques such as X-ray diffraction, NH3-temperature programmed desorption, scanning electron microscopy, 27Al NMR spectroscopy, surface area analysis, and thermogravimetric analysis. The catalytic activity results depicted that a high catalytic activity (>80%) with very high selectivity (>90%) to 1-propanol and 2-propanol was obtained over all the catalysts evaluated in a continuously fed, fixed-bed reactor. However, among all others, 2 wt% Pd/MoO3-Al2O3 catalyst was the most active and selective to propanols. The synergic interaction between the palladium and MoO3 on Al2O3 support and high strength weak to moderate acid sites of the catalyst were solely responsible for the high catalytic activity. The maximum glycerol conversion of 88.4% with 91.3% selectivity to propanols was achieved at an optimum reaction condition of 210 ∘ C and 1 bar pressure after 3 h of glycerol hydrogenolysis reaction.
      Citation: Catalysts
      PubDate: 2018-09-09
      DOI: 10.3390/catal8090385
      Issue No: Vol. 8, No. 9 (2018)
       
  • Catalysts, Vol. 8, Pages 386: Immobilized Biocatalysts

    • Authors: Peter Grunwald
      First page: 386
      Abstract: An application-related definition for immobilized enzymes was given by Chibata in 1978 […] 
      Citation: Catalysts
      PubDate: 2018-09-09
      DOI: 10.3390/catal8090386
      Issue No: Vol. 8, No. 9 (2018)
       
  • Catalysts, Vol. 8, Pages 387: Production of New Isoflavone Glucosides from
           Glycosylation of 8-Hydroxydaidzein by Glycosyltransferase from Bacillus
           subtilis ATCC 6633

    • Authors: Chien-Min Chiang, Tzi-Yuan Wang, Szu-Yi Yang, Jiumn-Yih Wu, Te-Sheng Chang
      First page: 387
      Abstract: 8-Hydroxydaidzein (8-OHDe) has been proven to possess some important bioactivities; however, the low aqueous solubility and stability of 8-OHDe limit its pharmaceutical and cosmeceutical applications. The present study focuses on glycosylation of 8-OHDe to improve its drawbacks in solubility and stability. According to the results of phylogenetic analysis with several identified flavonoid-catalyzing glycosyltransferases (GTs), three glycosyltransferase genes (BsGT110, BsGT292 and BsGT296) from the genome of the Bacillus subtilis ATCC 6633 strain were cloned and expressed in Escherichia coli. The three BsGTs were then purified and the glycosylation activity determined toward 8-OHDe. The results showed that only BsGT110 possesses glycosylation activity. The glycosylated metabolites were then isolated with preparative high-performance liquid chromatography and identified as two new isoflavone glucosides, 8-OHDe-7-O-β-glucoside and8-OHDe-8-O-β-glucoside, whose identity was confirmed by mass spectrometry and nuclear magnetic resonance spectroscopy. The aqueous solubility of 8-OHDe-7-O-β-glucoside and 8-OHDe-8-O-β-glucoside is 9.0- and 4.9-fold, respectively, higher than that of 8-OHDe. Moreover, more than 90% of the initial concentration of the two 8-OHDe glucoside derivatives remained after 96 h of incubation in 50 mM of Tris buffer at pH 8.0. In contrast, the concentration of 8-OHDe decreased to 0.8% of the initial concentration after 96 h of incubation. The two new isoflavone glucosides might have potential in pharmaceutical and cosmeceutical applications.
      Citation: Catalysts
      PubDate: 2018-09-10
      DOI: 10.3390/catal8090387
      Issue No: Vol. 8, No. 9 (2018)
       
  • Catalysts, Vol. 8, Pages 388: Rational Design of High Surface Area
           Mesoporous Ni/CeO2 for Partial Oxidation of Propane

    • Authors: Mohammad Peymani, Seyed Mehdi Alavi, Hamidreza Arandiyan, Mehran Rezaei
      First page: 388
      Abstract: A Ni loaded catalyst on mesoporous ceria, with a large surface area, prepared through the surfactant-assisted precipitation and impregnation method was investigated as an efficient catalyst for propane partial oxidation to produce synthesis gas. The results show that 2.5 wt% Ni/CeO2 had the optimum Ni loading, exhibiting the highest catalytic propane conversion. It also showed excellent stability, with no obvious activity drop after a 10 h time-on-stream reaction and slightly decreased in H2 and CO yields. The investigation of the reactant composition effect on carbon formation showed that by decreasing the C/O2 ratio the content of accumulated carbon decreased and propane conversion increased. The good activity of the Ni/CeO2 can be ascribed to the high surface area and rich surface defects of the ceria support and a high dispersion of active sites (Ni nanoparticles).
      Citation: Catalysts
      PubDate: 2018-09-10
      DOI: 10.3390/catal8090388
      Issue No: Vol. 8, No. 9 (2018)
       
  • Catalysts, Vol. 8, Pages 389: A Hybrid Reactor System Comprised of
           Non-Thermal Plasma and Mn/Natural Zeolite for the Removal of Acetaldehyde
           from Food Waste

    • Authors: Min Young Song, Hae Won Ryu, Sang-Chul Jung, JiHyeon Song, Byung-Joo Kim, Young-Kwon Park
      First page: 389
      Abstract: The degradation of low concentrations of acetaldehyde while using a non-thermal plasma (NTP)/catalyst hybrid reactor system was investigated while using humidified air at ambient temperature. A series of highly active manganese-impregnated natural zeolite (Mn/NZ) catalysts were synthesized by the incipient wetness method using sonication. The Mn/NZ catalysts were analyzed by Brunauer-Emmett-Teller surface area measurements and X-ray photoelectron spectroscopy. The Mn/NZ catalyst located at the downstream of a dc corona was used for the decomposition of ozone and acetaldehyde. The decomposition efficiency of ozone and acetaldehyde was increased significantly using the Mn/NZ catalyst with NTP. Among the various types of Mn/NZ catalysts with different Mn contents, the 10 wt.% Mn/NZ catalyst under the NTP resulted the highest ozone and acetaldehyde removal efficiency, almost 100% within 5 min. Moreover, this high efficiency was maintained for 15 h. The main reason for the high catalytic activity and stability was attributed to the high dispersion of Mn on the NZ made by the appropriate impregnation method using sonication. This system is expected to be efficient to decompose a wide range of volatile organic compounds with low concentrations.
      Citation: Catalysts
      PubDate: 2018-09-10
      DOI: 10.3390/catal8090389
      Issue No: Vol. 8, No. 9 (2018)
       
  • Catalysts, Vol. 8, Pages 390: Enhanced Catalytic Dechlorination of
           1,2-Dichlorobenzene Using Ni/Pd Bimetallic Nanoparticles Prepared by a
           Pulsed Laser Ablation in Liquid

    • Authors: Hyeon Jin Jung, Seung Jun Lee, Ravindranadh Koutavarapu, Sung Kuk Kim, Hyun Chul Choi, Myong Yong Choi
      First page: 390
      Abstract: Bimetallic nanoparticles (NPs) exhibit advantageous electrical, optical, and catalytic properties. Among the various NP synthesis methods, pulsed laser ablation in liquid (PLAL) is currently attracting much attention because of its simplicity and versatility. In this study, a pulsed laser was used to produce nickel/palladium (Ni/Pd) bimetallic NPs in methanol and deionized water. The morphological and optical properties of the resulting Ni/Pd bimetallic NPs were characterized. The synthesized Ni/Pd bimetallic NPs were used for the dechlorination of 1,2-dichlorobenzene (1,2-DCB) under various conditions. The dechlorination rates of 1,2-DCB while using single (Ni and Pd) and bimetallic (Ni powder/Pd and Ni/Pd) NPs were investigated. The results showed that the Ni/Pd bimetallic NPs with 19.16 wt.% Pd exhibited much enhanced degradation efficiency for 1,2-DCB (100% degradation after 30 min). Accordingly, the results of enhanced the degradation of 1,2-DCB provide plausible mechanism insights into the catalytic reaction.
      Citation: Catalysts
      PubDate: 2018-09-10
      DOI: 10.3390/catal8090390
      Issue No: Vol. 8, No. 9 (2018)
       
  • Catalysts, Vol. 8, Pages 391: Bio-Glycidol Conversion to Solketal over
           Acid Heterogeneous Catalysts: Synthesis and Theoretical Approach

    • Authors: Maria Ricciardi, Laura Falivene, Tommaso Tabanelli, Antonio Proto, Raffaele Cucciniello, Fabrizio Cavani
      First page: 391
      Abstract: The present work deals with the novel use of heterogeneous catalysts for the preparation of solketal from bio-glycidol. Sustainable feedstocks and mild reaction conditions are considered to enhance the greenness of the proposed process. Nafion NR50 promotes the quantitative and selective acetalization of glycidol with acetone. DFT calculations demonstrate that the favored mechanism consists in the nucleophilic attack of acetone to glycidol concerted with the ring opening assisted by the acidic groups on the catalyst and in the following closure of the five member ring of the solketal.
      Citation: Catalysts
      PubDate: 2018-09-11
      DOI: 10.3390/catal8090391
      Issue No: Vol. 8, No. 9 (2018)
       
  • Catalysts, Vol. 8, Pages 392: A Facile Synthesis of Visible-Light Driven
           Rod-on-Rod like α-FeOOH/α-AgVO3 Nanocomposite as Greatly Enhanced
           Photocatalyst for Degradation of Rhodamine B

    • Authors: Meng Sun, Raja Arumugam Senthil, Junqing Pan, Sedahmed Osman, Abrar Khan
      First page: 392
      Abstract: In this work, we have synthesized the rod-on-rod–like α-FeOOH/α-AgVO3 nanocomposite photocatalysts with the different amounts of solvothermally synthesized α-FeOOH nanorods via a simple co-precipitation method. The as-synthesized photocatalysts were characterized by X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy, UV−Visible diffuse reflectance spectroscopy, scanning electron microscopy (SEM), element mapping, high-resolution transmission electron microscopy (HR-TEM) and X-ray photoelectron spectroscopy (XPS) analysis. The observed SEM images show that both α-AgVO3 and α-FeOOH exhibits the rod-shaped morphology with nano size. Furthermore, the photocatalytic activities of the obtained photocatalysts were evaluated towards the degradation of Rhodamine B (RhB) under visible-light irradiation. It is demonstrated that the 3 mg α-FeOOH added to the α-FeOOH/α-AgVO3 nanocomposite exhibited an enhanced photocatalytic performance as compared with the pure α-AgVO3 and α-FeOOH. This significant improvement can be attributed to the increased photo-excited electron-hole pair separation efficiency, large portion of visible-light absorption ability and the reduced recombination of the electron-hole pair. The recycling test revealed that the optimized nanocomposite exhibited good photostability and reusability properties. In addition, the believable photodegradation mechanism of RhB using α-FeOOH/α-AgVO3 nanocomposite is proposed. Hence, the developed α-FeOOH/α-AgVO3 nanocomposite is a promising material for the degradation of organic pollutants in an aqueous environment.
      Citation: Catalysts
      PubDate: 2018-09-12
      DOI: 10.3390/catal8090392
      Issue No: Vol. 8, No. 9 (2018)
       
  • Catalysts, Vol. 8, Pages 393: A Zn-MOF-Catalyzed Terpolymerization of an
           Epoxide, CO2, and β-butyrolactone

    • Authors: Sudakar Padmanaban, Sivanesan Dharmalingam, Sungho Yoon
      First page: 393
      Abstract: The terpolymerization of propylene oxide (PO), CO2, and a lactone is one of the prominent sustainable procedures for synthesizing thermoplastic materials at an industrial scale. Herein, the one-pot terpolymerization of PO, CO2, and β-butyrolactone (BBL) was achieved for the first time using a heterogeneous nano-sized catalyst: zinc glutarate (ZnGA-20). The reactivity of both PO and BBL increased with the CO2 pressure, and the polyester content of the terpolymer poly (carbonate-co-ester) could be tuned by controlling the infeed ratio of PO to BBL. When the polyester content increased, the thermal stability of the polymers increased, whereas the glass transition temperature (Tg) decreased.
      Citation: Catalysts
      PubDate: 2018-09-13
      DOI: 10.3390/catal8090393
      Issue No: Vol. 8, No. 9 (2018)
       
  • Catalysts, Vol. 8, Pages 394: Synthesis of Stable Hierarchical MIL-101(Cr)
           with Enhanced Catalytic Activity in the Oxidation of Indene

    • Authors: Tian Zhao, Ming Dong, Ling Yang, Yuejun Liu
      First page: 394
      Abstract: Nowadays, the controllable synthesis of stable hierarchical metal–organic frameworks (MOFs) is very important for practical applications, especially in catalysis. Herein, a well-known chromium–benzenedicarboxylate metal–organic framework, MIL-101(Cr), with a stable hierarchical structure, was produced by using phenylphosphonic acid (PPOA) as a modulator via the hydrothermal method. The presence of phenylphosphonic acid could create structural defects and generate larger mesopores. The synthesized hierarchical MIL-101(Cr) possesses relatively good porosity, and the larger mesopores had widths of 4–10 nm. The hierarchical MIL-101(Cr) showed significant improvement for catalytic activity in the oxidation of indene. Further, the presence of a hierarchical structure could largely enhance large dye molecule uptake properties by impregnating.
      Citation: Catalysts
      PubDate: 2018-09-13
      DOI: 10.3390/catal8090394
      Issue No: Vol. 8, No. 9 (2018)
       
  • Catalysts, Vol. 8, Pages 395: Microemulsion-Based One-Step Electrochemical
           Fabrication of Mesoporous Catalysts

    • Authors: Albert Serrà, Elisa Vallés
      First page: 395
      Abstract: Electrochemical technology has been proposed as an alternative or complementary method to classical inorganic synthesis for the fabrication of effective metallic solid catalysts. Microemulsion-based electrodeposition is a novel, fast, and one-step procedure to obtain mesoporous catalysts with extraordinarily effective areas, which can be used in heterogeneous catalysis for degradation of pollutants and clean energy production. The fabrication process involves conducting microemulsions containing ionic species (dissolved in aqueous solutions) as precursors of the metallic catalysts. The presence of nanometric droplets of organic or ionic-liquid components in the microemulsion defines the mesoporosity of the catalysts during a one-step electrodeposition process. This method also allows the fabrication of metal catalysts as supported mesoporous films or mesoporous nanowires with very high effective areas. Additionally, reactants have excellent accessibility to the overall surface of the catalysts. The different catalysts fabricated with the help of this technology have been tested for competitive degradation of organic pollutants and anodes' materials for fuel cell devices.
      Citation: Catalysts
      PubDate: 2018-09-14
      DOI: 10.3390/catal8090395
      Issue No: Vol. 8, No. 9 (2018)
       
  • Catalysts, Vol. 8, Pages 396: Wetting Fraction in a Tubular Reactor with
           Solid Foam Packing and Gas/Liquid Co-Current Downflow

    • Authors: Iman Mohammed, Uwe Hampel
      First page: 396
      Abstract: The performance of fixed-bed reactors with structured catalysts depends heavily on the gas–liquid–solid contacting pattern. For a broad range of flow conditions, the liquid phase does not cover the solid surface of the packing homogeneously; this is known as partial wetting. The wetting fraction in solid foams was obtained using a modified electrochemical measurement method with adaption of the limiting-current technique in different pre-wetting scenarios. The external wetting fraction, which is defined as fraction of the external solid-foam area covered by the liquid phase to the total external solid-foam area, is directly linked to the overall rate of reaction through the overall liquid mass transfer rate. The wetting fraction decreased with an increase in foam density, a process which was related to decreasing the strut thickness, increasing foam surface area, and consequently, decreasing the wetted area. Additionally, the results indicate that a better distribution of liquid and an increased wetting fraction occurred when a spray nozzle distributor was applied. A new wetting correlation for solid foams is proposed to estimate the wetting fraction with consideration of foam morphology and flow regime.
      Citation: Catalysts
      PubDate: 2018-09-14
      DOI: 10.3390/catal8090396
      Issue No: Vol. 8, No. 9 (2018)
       
  • Catalysts, Vol. 8, Pages 397: Hydrotreating of Light Cycle Oil over
           Supported on Porous Aromatic Framework Catalysts

    • Authors: Eduard Karakhanov, Anton Maximov, Yulia Kardasheva, Maria Vinnikova, Leonid Kulikov
      First page: 397
      Abstract: The hydroprocessing of substituted naphthalenes and light cycle oil (LCO) over bimetallic Ni-W-S and Ni-Mo-S catalysts that were obtained by decomposition of [N(n-Bu)4]2[Ni(MeS4)2] (Me = W, Mo) complexes in situ in the pores of mesoporous aromatic frameworks (PAFs) during the reaction, was studied. The promotion of acid-catalyzed processes by PAF-AlCl3, synthesized by impregnation of a PAF with AlCl3 from its toluene solution, was investigated. It has been found that Ni-W-S catalytic systems were more active in the hydrodearomatization reactions, while Ni-Mo-S catalytic systems were more active in hydrodesulfurization and hydrocracking reactions. The introduction of sulfur into the reaction medium enhanced the activity of the catalysts and the presence of PAF-AlCl3 led to an acceleration of the hydrocracking processes.
      Citation: Catalysts
      PubDate: 2018-09-14
      DOI: 10.3390/catal8090397
      Issue No: Vol. 8, No. 9 (2018)
       
  • Catalysts, Vol. 8, Pages 398: Catalytic Transformation of Lignocellulosic
           Platform Chemicals

    • Authors: Anna Maria Raspolli Galletti
      First page: 398
      Abstract: n/a
      Citation: Catalysts
      PubDate: 2018-09-16
      DOI: 10.3390/catal8090398
      Issue No: Vol. 8, No. 9 (2018)
       
  • Catalysts, Vol. 8, Pages 399: Performance of Mn-Fe-Ce/GO-x for Catalytic
           Oxidation of Hg0 and Selective Catalytic Reduction of NOx in the Same
           Temperature Range

    • Authors: Donghai An, Xiaoyang Zhang, Xingxing Cheng, Yong Dong
      First page: 399
      Abstract: A series of composites of Mn-Fe-Ce/GO-x have been synthesized by a hydrothermal method. Their performance in simultaneously performing the catalytic oxidation of Hg0 and the selective catalytic reduction of nitrogen oxides (NOx) in the same temperature range were investigated. In order to investigate the physicochemical properties and surface reaction, basic tests, including Brunauer-Emmett-Teller (BET), XRD, scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS) were selected. The results indicate that the active components deposited on graphene play an important role in the removal of mercury and NOx, with different valences. Especially, the catalyst of Mn-Fe-Ce/GO-20% possesses an excellent efficiency in the temperature range of 170 to 250 °C. Graphene has a huge specific surface area and good mechanical property; thus, the active components of the Mn-Fe-Ce catalyst can be highly dispersed on the surface of graphene oxide. In addition, the effects of O2, H2O, NO and SO2 on the removal efficiency of Hg0 were examined in flue gas. Furthermore, the regeneration experiments conducted by thermal methods proved to be promising methods.
      Citation: Catalysts
      PubDate: 2018-09-18
      DOI: 10.3390/catal8090399
      Issue No: Vol. 8, No. 9 (2018)
       
  • Catalysts, Vol. 8, Pages 400: Biosynthesis of Nylon 12 Monomer,
           ω-Aminododecanoic Acid Using Artificial Self-Sufficient P450, AlkJ and
           ω-TA

    • Authors: Md Murshidul Ahsan, Mahesh D. Patil, Hyunwoo Jeon, Sihyong Sung, Taeowan Chung, Hyungdon Yun
      First page: 400
      Abstract: ω-Aminododecanoic acid is considered as one of the potential monomers of Nylon 12, a high-performance member of the bioplastic family. The biosynthesis of ω-aminododecanoic acid from renewable sources is an attractive process in the polymer industry. Here, we constructed three artificial self-sufficient P450s (ArtssP450s) using CYP153A13 from Alcanivorax borkumensis and cytochrome P450 reductase (CPR) domains of natural self-sufficient P450s (CYP102A1, CYP102A5, and 102D1). Among them, artificial self-sufficient P450 (CYP153A13BM3CPR) with CYP102A1 CPR showed the highest catalytically activity for dodecanoic acid (DDA) substrate. This form of ArtssP450 was further co-expressed with ω-TA from Silicobacter pomeroyi and AlkJ from Pseudomonas putida GPo1. This single-cell system was used for the biotransformation of dodecanoic acid (DDA) to ω-aminododecanoic acid (ω-AmDDA), wherein we could successfully biosynthesize 1.48 mM ω-AmDDA from 10 mM DDA substrate in a one-pot reaction. The productivity achieved in the present study was five times higher than that achieved in our previously reported multistep biosynthesis method (0.3 mM).
      Citation: Catalysts
      PubDate: 2018-09-18
      DOI: 10.3390/catal8090400
      Issue No: Vol. 8, No. 9 (2018)
       
  • Catalysts, Vol. 8, Pages 401: Immobilization of Chitosanases onto Magnetic
           Nanoparticles to Enhance Enzyme Performance

    • Authors: Wei Wang, Na Guo, Wencan Huang, Zhaohui Zhang, Xiangzhao Mao
      First page: 401
      Abstract: In this study, chitosanase cloning from Streptomyces albolongus was fermented and purified by a Ni-NTA column. Fe3O4-SiO2 magnetite nanoparticles (MNPs) were synthesized by the co-precipitation method coating with silica via a sol-gel reaction and were then amino functioned by treating with 3-aminopropyltriethoxysilane. Chitosanases were immobilized onto the surface of MNPs by covalent bonding (MNPs@chitosanase). Transmission electron microscopy (TEM), Fourier transform infrared spectrometer (FT–IR), and magnetic measurements were used to illustrate the MNPs and immobilized chitosanase. The optimal conditions of immobilization were studied. The thermal, pH, and stabilities of immobilized chitosanase were tested and the results showed that the stabilities were significantly enhanced compared with free chitosanase. After being recycled 10 times, the residual activity of the immobilized chitosanase was 43.7% of the initial activity.
      Citation: Catalysts
      PubDate: 2018-09-18
      DOI: 10.3390/catal8090401
      Issue No: Vol. 8, No. 9 (2018)
       
  • Catalysts, Vol. 8, Pages 402: Synergistic Degradation of Dye Wastewaters
           Using Binary or Ternary Oxide Systems with Immobilized Laccase

    • Authors: Katarzyna Antecka, Jakub Zdarta, Katarzyna Siwińska-Stefańska, Grzegorz Sztuk, Ewelina Jankowska, Piotr Oleskowicz-Popiel, Teofil Jesionowski
      First page: 402
      Abstract: In recent years, groundwater contamination caused by dyes has become an important problem. They enter into wastewater as a result of the textile, automotive, or cosmetics industries. For this reason, new methods are being sought, which would aid at the removal of dye impurities with high efficiency and also would be relatively cheap. In the presented study synthesized TiO2-ZrO2 (with TiO2:ZrO2 molar ratio of 8:2) and TiO2-ZrO2-SiO2 (with TiO2:ZrO2:SiO2 molar ratio of 8:1:1) oxide materials were used as supports for enzyme immobilization. Effective synthesis of the carriers was confirmed by results of scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), low-temperature nitrogen sorption and Fourier transform infrared spectroscopy (FTIR). The materials achieve high immobilization efficiency of the laccases from Trametes versicolor (83% and 96% for TiO2-ZrO2-laccase and TiO2-ZrO2-SiO2-laccase, respectively). The effect of selected dye concentrations, pH, temperature, and reusability were also tested. The obtained results showed that after removal of textile dyes, such as Alizarin Red S (ARS), Remazol Brilliant Blue R (RBBR), and Reactive Black 5 (RB5), under optimal process conditions, which were pH 5 and 25 °C, from dye solution of 5 mg/L degradation efficiency reached 100%, 91%, and 77%, respectively, suggesting synergistic mechanism of degradation by simultaneous sorption and catalytic action. Finally, reduction of chemical oxygen demand (COD) of the solution after treatment indicated lower mixture toxicity and effective dye degradation.
      Citation: Catalysts
      PubDate: 2018-09-18
      DOI: 10.3390/catal8090402
      Issue No: Vol. 8, No. 9 (2018)
       
  • Catalysts, Vol. 8, Pages 403: Photooxidation of Cyclohexane by Visible and
           Near-UV Light Catalyzed by Tetraethylammonium Tetrachloroferrate

    • Authors: Kira M. Fahy, Adam C. Liu, Kelsie R. Barnard, Valerie R. Bright, Robert J. Enright, Patrick E. Hoggard
      First page: 403
      Abstract: Tetraethylammonium tetrachloroferrate catalyzes the photooxidation of cyclohexane heterogeneously, exhibiting significant photocatalysis even in the visible portion of the spectrum. The photoproducts, cyclohexanol and cyclohexanone, initially develop at constant rates, implying that the ketone and the alcohol are both primary products. The yield is improved by the inclusion of 1% acetic acid in the cyclohexane. With small amounts of catalyst, the reaction rate increases with the amount of catalyst employed, but then passes through a maximum and decreases, due to increased reflection of the incident light. The reaction rate also passes through a maximum as the percentage of dioxygen above the sample is increased. This behavior is due to quenching by oxygen, which at the same time is a reactant. Under one set of reaction conditions, the photonic efficiency at 365 nm was 0.018 mol/Einstein. Compared to TiO2 as a catalyst, Et4N[FeCl4] generates lower yields at wavelengths below about 380 nm, but higher yields at longer wavelengths. Selectivity for cyclohexanol is considerably greater with Et4N[FeCl4], and oxidation does not proceed past cyclohexanone.
      Citation: Catalysts
      PubDate: 2018-09-19
      DOI: 10.3390/catal8090403
      Issue No: Vol. 8, No. 9 (2018)
       
  • Catalysts, Vol. 8, Pages 404: Covalent Organic Frameworks: Promising
           Materials as Heterogeneous Catalysts for C-C Bond Formations

    • Authors: Dongge Ma, Yi Wang, Anan Liu, Shuhong Li, Chichong Lu, Chuncheng Chen
      First page: 404
      Abstract: Covalent organic frameworks (COFs) are defined as highly porous and crystalline polymers, constructed and connected via covalent bonds, extending in two- or three-dimension. Compared with other porous materials such as zeolite and active carbon, the versatile and alternative constituent elements, chemical bonding types and characteristics of ordered skeleton and pore, enable the rising large family of COFs more available to diverse applications including gas separation and storage, optoelectronics, proton conduction, energy storage and in particular, catalysis. As the representative candidate of next-generation catalysis materials, because of their large surface area, accessible and size-tunable open nano-pores, COFs materials are suitable for incorporating external useful active ingredients such as ligands, complexes, even metal nanoparticles deposition and substrate diffusion. These advantages make it capable to catalyze a variety of useful organic reactions such as important C-C bond formations. By appropriate pore-engineering in COFs materials, even enantioselective asymmetric C-C bond formations could be realized with excellent yield and ee value in much shorter reaction time compared with their monomer and oligomer analogues. This review will mainly introduce and discuss the paragon examples of COFs materials for application in C-C bond formation reactions for the organic synthetic purpose.
      Citation: Catalysts
      PubDate: 2018-09-19
      DOI: 10.3390/catal8090404
      Issue No: Vol. 8, No. 9 (2018)
       
  • Catalysts, Vol. 8, Pages 405: Molecular-Level Understanding of Selectively
           Photocatalytic Degradation of Ammonia via Copper Ferrite/N-Doped Graphene
           Catalyst under Visible Near-Infrared Irradiation

    • Authors: Hang Zhang, Yang Zhou, Shou-Qing Liu, Qin-Qin Gu, Ze-Da Meng, Li Luo
      First page: 405
      Abstract: Developing photocatalysts with molecular recognition function is very interesting and desired for specific applications in the environmental field. Copper ferrite/N-doped graphene (CuFe2O4/NG) hybrid catalyst was synthesized and characterized by surface photovoltage spectroscopy, X-ray powder diffraction, transmission electron microscopy, Raman spectroscopy, UV–Vis near-infrared diffuse reflectance spectroscopy and X-ray photoelectron spectroscopy. The CuFe2O4/NG catalyst can recognize ammonia from rhodamine B (RhB) in ammonia-RhB mixed solution and selectively degrade ammonia under visible near-infrared irradiation. The degradation ratio for ammonia reached 92.6% at 6 h while the degradation ratio for RhB was only 39.3% in a mixed solution containing 100.0 mg/L NH3-N and 50 mg/L RhB. Raman spectra and X-ray photoelectron spectra indicated ammonia adsorbed on CuFe2O4 while RhB was adsorbed on NG. The products of oxidized ammonia were detected by gas chromatography, and results showed that N2 was formed during photocatalytic oxidization. Mechanism studies showed that photo-generated electrons flow to N-doped graphene following the Z-scheme configuration to reduce O2 dissolved in solution, while photo-generated holes oxidize directly ammonia to nitrogen gas.
      Citation: Catalysts
      PubDate: 2018-09-20
      DOI: 10.3390/catal8100405
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 406: Photocatalytic Inactivation of Bacteriophage
           f2 with Ag3PO4/g-C3N4 Composite under Visible Light Irradiation:
           Performance and Mechanism

    • Authors: Rong Cheng, Liang-jie Shen, Jin-hui Yu, Shao-yu Xiang, Xiang Zheng
      First page: 406
      Abstract: Water-borne virus pollution has caused great harm and attracted widespread attention in many countries. Visible-light-driven photocatalysis is considered as a promising process for disinfection. In this study, Ag3PO4/g-C3N4 (AgCN) composites were synthesized by hydrothermal method. The photocatalytic disinfection was investigated using bacteriophage f2 as the model virus. Moreover, the effects of pH and humic acid on photocatalytic disinfection were studied. Meanwhile, the mechanism of enhanced disinfection by Ag3PO4/g-C3N4 was systematically investigated by radical scavenger experiments. The results show that Ag3PO4 particles were uniformly distributed on g-C3N4 sheets. By means of photoluminescence spectrometer analysis, it is confirmed that a lower carrier recombination rate for Ag3PO4/g-C3N4 was achieved compared with Ag3PO3 and g-C3N4. Meanwhile, complete inactivation of f2 with concentration of 3 × 106 PFU/mL was reached within 80 min in the presence of Ag3PO4/g-C3N4 composite. The pH had little effect on removal efficiency overall, while the existence of humic acid resulted in a significant negative effect on the inactivation of f2 due to the optical shielding and absorption of humic acid. Recycling tests of Ag3PO4/g-C3N4 confirmed that Ag3PO4/g-C3N4 presented superior stability. The results from radical scavenger experiments indicated that holes (h+) and hydroxyl radicals (·OH) played important roles in photocatalytic disinfection process.
      Citation: Catalysts
      PubDate: 2018-09-20
      DOI: 10.3390/catal8100406
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 407: Determination of Uric Acid in Co-Presence of
           Dopamine and Ascorbic Acid Using Cuprous Oxide Nanoparticle-Functionalized
           Graphene Decorated Glassy Carbon Electrode

    • Authors: Jingheng Ning, Quanguo He, Xin Luo, Min Wang, Donglin Liu, Jianhui Wang, Guangli Li, Jun Liu
      First page: 407
      Abstract: Cuprous oxide nanoparticles (Cu2O NPs) were dispersed into a graphene oxide (GO) solution to form a homogeneous Cu2O-GO dispersion. After this, the cuprous oxide nanoparticles were functionalized to electrochemically reduce the graphene oxide decorated glassy carbon electrode (Cu2O-ErGO/GCE). This was prepared by coating the Cu2O-GO dispersion onto the surface of the glassy carbon electrode (GCE), which was followed by a potentiostatic reduction process. An irreversible two-electron reaction of uric acid (UA) was observed at the voltammetric sensor. Moreover, the high concentrations of dopamine (DA) and ascorbic acid (AA) hardly affected the peak current of UA, which suggested that Cu2O-ErGO/GCE have excellent selectivity for UA. This is probably because the response peaks of the three compounds are well-separated from each other. The oxidation peak current was proportional to the concentration of UA in the ranges of 2.0 nM−0.6 μM and 0.6 μM−10 μM, respectively, with a low limit of detection (S/N = 3, 1.0 nM) after an accumulation time of 120 s. Cu2O-ErGO/GCE was utilized for the rapid detection of UA in human blood serum and urine samples with satisfactory results.
      Citation: Catalysts
      PubDate: 2018-09-20
      DOI: 10.3390/catal8100407
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 408: Erratum: Zhang, Y., et al. Interface-Active
           Metal Organic Frameworks for Knoevenagel Condensations in Water. Catalysts
           2018, 8, 315

    • Authors: Catalysts Editorial Office
      First page: 408
      Abstract: n/a
      Citation: Catalysts
      PubDate: 2018-09-20
      DOI: 10.3390/catal8100408
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 409: Photocatalytic Treatment of An Actual
           Confectionery Wastewater Using Ag/TiO2/Fe2O3: Optimization of
           Photocatalytic Reactions Using Surface Response Methodology

    • Authors: Yi Ping Lin, Mehrab Mehrvar
      First page: 409
      Abstract: Titanium dioxide (TiO2) photocatalysis is one of the most commonly studied advanced oxidation processes (AOPs) for the mineralization of deleterious and recalcitrant compounds present in wastewater as it is stable, inexpensive, and effective. Out of all, doping with metal and non-metals, and the heterojunction with another semiconductor were proven to be efficient methods in enhancing the degradation of organic pollutants under ultraviolet (UV) and visible light. However, complex degradation processes in the treatment of an actual wastewater are difficult to model and optimize. In the present study, the application of a modified photocatalyst, Ag/TiO2/Fe2O3, for the degradation of an actual confectionery wastewater was investigated. Factorial studies and statistical design of experiments using the Box-Behnken method along with response surface methodology (RSM) were employed to identify the individual and cross-factor effects of independent parameters, including light wavelength (nm), photocatalyst concentration (g/L), initial pH, and initial total organic carbon (TOC) concentration (g/L). The maximum TOC removal at optimum conditions of light wavelength (254 nm), pH (4.68), photocatalyst dosage (480 mg/L), and initial TOC concentration (11,126.5 mg/L) was determined through the numerical optimization method (9.78%) and validated with experimental data (9.42%). Finally, the first-order rate constant with respect to TOC was found to be 0.0005 min−1 with a residual value of 0.998.
      Citation: Catalysts
      PubDate: 2018-09-21
      DOI: 10.3390/catal8100409
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 410: Brønsted and Lewis Solid Acid Catalysts in
           the Valorization of Citronellal

    • Authors: Federica Zaccheria, Federica Santoro, Elvina Dhiaul Iftitah, Nicoletta Ravasio
      First page: 410
      Abstract: Terpenes are valuable starting materials for the synthesis of molecules that are of interest to the flavor, fragrance, and pharmaceutical industries. However, most processes involve the use of mineral acids or homogeneous Lewis acid catalysts. Here, we report results obtained in the liquid-phase reaction of citronellal with anilines under heterogeneous catalysis conditions to give tricyclic compounds with interesting pharmacological activity. The terpenic aldehyde could be converted into octahydroacridines with a 92% yield through an intramolecular imino Diels–Alder reaction of the imine initially formed in the presence of an acidic clay such as Montmorillonite KSF. Selectivity to the desired product strongly depended on the acid sites distribution, with Brønsted acids favoring selectivity to octahydroacridine and formation of the cis isomer. Pure Lewis acids such as silica–alumina with a very low amount of alumina gave excellent results with electron-rich anilines like toluidine and p-anisidine. This protocol can be applied starting directly from essential oils such as kaffir lime oil, which has a high citronellal content.
      Citation: Catalysts
      PubDate: 2018-09-22
      DOI: 10.3390/catal8100410
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 411: Versatile Synthesis of Pd and Cu Co-Doped
           Porous Carbon Nitride Nanowires for Catalytic CO Oxidation Reaction

    • Authors: Kamel Eid, Yahia H. Ahmad, Assem T. Mohamed, Anas G. Elsafy, Siham Y. Al-Qaradawi
      First page: 411
      Abstract: Developing efficient catalyst for CO oxidation at low-temperature is crucial in various industrial and environmental remediation applications. Herein, we present a versatile approach for controlled synthesis of carbon nitride nanowires (CN NWs) doped with palladium and copper (Pd/Cu/CN NWs) for CO oxidation reactions. This is based on the polymerization of melamine by nitric acid in the presence of metal-precursors followed by annealing under nitrogen. This intriguingly drove the formation of well-defined, one-dimensional nanowires architecture with a high surface area (120 m2 g−1) and doped atomically with Pd and Cu. The newly-designed Pd/Cu/CN NWs fully converted CO to CO2 at 149 °C, that was substantially more active than that of Pd/CN NWs (283 °C) and Cu/CN NWs (329 °C). Moreover, Pd/Cu/CN NWs fully reserved their initial CO oxidation activity after 20 h. This is mainly attributed to the combination between the unique catalytic properties of Pd/Cu and outstanding physicochemical properties of CN NWs, which tune the adsorption energies of CO reactant and reaction product during the CO oxidation reaction. The as-developed method may open new frontiers on using CN NWs supported various noble metals for CO oxidation reaction.
      Citation: Catalysts
      PubDate: 2018-09-22
      DOI: 10.3390/catal8100411
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 412: Synthesis of Bimetallic Gold-Silver (Au-Ag)
           Nanoparticles for the Catalytic Reduction of 4-Nitrophenol to
           4-Aminophenol

    • Authors: Nurafaliana Berahim, Wan Jefrey Basirun, Bey Fen Leo, Mohd Rafie Johan
      First page: 412
      Abstract: Bimetallic gold-silver nanoparticles as unique catalysts were prepared using seed colloidal techniques. The catalytic capabilities of the nanoparticles were ascertained in the reduction of 4-nitrophenol to 4-aminophenol in the presence of sodium borohydride. Our results clearly showed that the rate of 4-NP reduction to 4-AP increased with a corresponding decrease in the diameter of the bimetallic NPs. The Au-Ag nanoparticles prepared with 5.0 mL Au seed volume indicated higher reduction activity, which was approximately 1.2 times higher than that of 2.0 mL Au seed volume in the reductive conversion of 4-NP to 4-AP. However, the monometallic NPs showed relatively less catalytic activity in the reductive conversion of 4-NP to 4-AP compared to bimetallic Au-Ag nanoparticles. Our studies also reinforced the improved catalytic properties of the bimetallic Au-Ag nanoparticles structure with a direct impact of the size or diameter and relative composition of the bimetallic catalytic nanoparticles.
      Citation: Catalysts
      PubDate: 2018-09-25
      DOI: 10.3390/catal8100412
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 413: Effect of Ce Doping of a Co/Al2O3 Catalyst
           on Hydrogen Production via Propane Steam Reforming

    • Authors: Jeong Yeon Do, Rama Krishna Chava, Namgyu Son, Junyeong Kim, No-Kuk Park, Doyeon Lee, Myung Won Seo, Ho-Jung Ryu, Jun Hwa Chi, Misook Kang
      First page: 413
      Abstract: We synthesized cerium-doped cobalt-alumina (CoxCey/Al2O3) catalysts for the propane steam reforming (PSR) reaction. Adding cerium introduces oxygen vacancies, and the oxygen transfer capacity of the Ce promoter favors CO to CO2 conversion during PSR, inhibiting coke deposition and promoting hydrogen production. The best PSR activity was achieved at 700 °C using the Co0.85Ce0.15/Al2O3 catalyst, which showed 100% propane (C3H8) conversion and about 75% H2 selectivity, and 6% CO, 5% CO2, and 4% CH4 were obtained. In contrast, the H2 selectivity of the base catalyst, Co/Al2O3, is 64%. The origin of the difference in activity was the lower C3H8 gas desorption temperature of the Co0.85Ce0.15/Al2O3 catalyst compared to that of the Co/Al2O3 catalyst; thus, the PSR occurred at low temperatures. Furthermore, more CO was adsorbed on the Co0.85Ce0.15/Al2O3 catalyst, and subsequently, desorbed as CO2. The activation energy for water desorption from the Co0.85Ce0.15/Al2O3 catalyst was 266.96 kJ/mol, higher than that from Co/Al2O3. Furthermore, the water introduced during the reaction probably reacted with CO on the Co0.85Ce0.15/Al2O3 catalyst, increasing CO2 generation. Finally, we propose a mechanism involving the Co0.85Ce0.15/Al2O3 catalyst, wherein propane is reformed on CoxCey sites, forming H2, and CO, followed by the conversion of CO to CO2 by water on CeO2 sites.
      Citation: Catalysts
      PubDate: 2018-09-25
      DOI: 10.3390/catal8100413
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 414: Laccase-Catalyzed Reduction of Oxygen at
           Electrodes Modified by Carbon Nanotubes with Adsorbed Promazine or
           Acetosyringone

    • Authors: Bartłomiej Olszewski, Krzysztof Stolarczyk
      First page: 414
      Abstract: One of the problems with the use of enzymes as catalysts in biofuel cells is to achieve good contact between the enzyme and the electrode surface. One solution to this problem is the use of various nanostructures such as carbon nanotubes, fullerenes, graphene derivatives, gold nanoparticles, as well as mediators for the construction of electrodes. Acetosyringone and promazine adsorbed on glassy carbon electrodes (GCEs) covered with multiwall carbon nanotubes (MWCNTs) and laccase were used as biocathodes. These mediators showed very efficient adsorption on modified glassy carbon electrodes covered with MWCNTs and enabled efficient and stable adsorption of laccase, which acts as the bioelectrocatalyst. Very good electrical contact between the electrode surface and the laccase enzymatic active sites made it possible to increase the catalytic current density of oxygen-reduction by about 82% compared to electrodes without mediators. Application of acetosyringone and promazine used in the construction of biocathode also improved the current and power of the biobattery ca. twice comparing to the system without mediators. The device output reached the power that equaled approximately 2 mW/cm2 at 0.8 V and open circuit potential (OCP) was 1.6 V. The systems elaborated proved also useful in oxygen sensing and allowed to determine lower oxygen concentrations in solution compared to the GCE modified with MWCNTs and laccase alone. The electrode showed also better stability in long-timescale measurements.
      Citation: Catalysts
      PubDate: 2018-09-25
      DOI: 10.3390/catal8100414
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 415: Evolution of Copper Supported on Fe3O4
           Nanorods for WGS Reaction

    • Authors: Lingjuan Ma, Hongbin Ma, Dawei Han, Mingyue Qiu, Yafei Guan, Yanlei Hu
      First page: 415
      Abstract: Rod-shaped Cu1Fe9Ox precursor was successfully prepared through an aqueous precipitation method. The shape and phase composition were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). It was found that Cu1Fe9Ox is composed of CuFe2O4 and Fe2O3. The reduction performance of Cu1Fe9Ox was studied by in situ XRD and H2 temperature-programmed reduction (H2-TPR). Cu/Fe3O4 nanorod catalyst is obtained through the controllable reduction of Cu1Fe9Ox nanorod, and the formed Cu/Fe3O4 nanorod catalyst does not have low-temperature water gas shift (WGS) activity, but exhibits high-temperature WGS reaction activity. Ambient pressure X-ray photoelectron spectroscopy (AP-XPS) studies showed that the main species of copper is Cu+ during the WGS reaction. The interaction between Cu and Fe3O4 rod and phase evolution of Cu species are quite different from Cu/Fe3O4 nanoparticles.
      Citation: Catalysts
      PubDate: 2018-09-25
      DOI: 10.3390/catal8100415
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 416: OcUGT1-Catalyzed Glucosylation of Sulfuretin
           Yields Ten Glucosides

    • Authors: Shuai Yuan, Yan-Li Xu, Yan Yang, Jian-Qiang Kong
      First page: 416
      Abstract: Sulfuretin glucosides are important sources of innovative drugs. However, few glucosides of sulfuretin have been observed in nature. Therefore, it is urgent to diversify sulfuretin glycosides. Herein, glycosyltransferase (GT)-catalyzed glycodiversification of sulfuretin was achieved. Specifically, a flavonoid GT designated as OcUGT1 was used as a biocatalyst for the glucosylation of sulfuretin with UDP-Glc. The OcUGT1-assisted glucosylation of sulfuretin yielded ten glycosylated products, including three monoglucosides, five diglucosides and two triglucosides. The three monoglucosides were thus identified to be sulfuretin 3′-, 4′- and 6-glucoside according to HR-ESI-TOFMS data and their coelution with respective standards. A major diglucoside was assigned as sulfuretin 4′,6-diglucoside by HR-ESI-TOFMS in conjunction with NMR analysis. The exact structure of the other four diglucosides was not well characterized due to their trace amount. However, they were reasonably inferred as sulfuretin 3′,6-diglucoside, sulfuretin 3′,4′-diglucoside and two disaccharide glucosides. In addition, the structural identification of the remaining two triglucosides was not performed because of their small amount. However, one of the triglucosides was deduced to be sulfuretin 3′,4′,6-triglucoside based on the catalytic behavior of OcUGT1. Of the ten sulfuretin glucosides, at least six were new compounds. This is the first time to obtain monoglucosides, diglucosides and triglucosides of sulfuretin simultaneously by a single glycosyltransferase.
      Citation: Catalysts
      PubDate: 2018-09-25
      DOI: 10.3390/catal8100416
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 417: Effect of H2O and O2 on the Adsorption and
           Degradation of Acetaldehyde on Anatase Surfaces—An In Situ ATR-FTIR
           Study

    • Authors: Stephanie Melchers, Jenny Schneider, Alexei V. Emeline, Detlef W. Bahnemann
      First page: 417
      Abstract: The effect of H2O and O2 on the adsorption and degradation of gaseous acetaldehyde on the anatase TiO2 surface has been studied, in the dark and upon UV illumination, at ambient temperatures. The processes occurring at the surface have been elucidated by means of in situ ATR–FTIR (Attenuated Total Reflection—Fourier Transform Infrared) spectroscopy, while gas detectors allowed the analysis of the adducts and products in the gas phase. In the dark and under dry conditions acetaldehyde reacts independently of the atmosphere, upon aldol condensation to crotonaldehyde. However, under humid conditions, this reaction was prevented due to the replacement of the adsorbed acetaldehyde molecules, by water molecules. Upon UV illumination under oxygenic conditions, acetaldehyde was decomposed to acetate and formate. Under an N2 atmosphere, the formation of acetate and formate was observed during the first hour of illumination, until all adsorbed oxygen had been consumed. In the absence of molecular oxygen acetate, methane, and CO2 were detected, the formation of which most likely involved the participation of the bridging O atoms, within the TiO2 lattice.
      Citation: Catalysts
      PubDate: 2018-09-25
      DOI: 10.3390/catal8100417
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 418: Influence of Bio-Oil Phospholipid on the
           Hydrodeoxygenation Activity of NiMoS/Al2O3 Catalyst

    • Authors: Muhammad Abdus Salam, Derek Creaser, Prakhar Arora, Stefanie Tamm, Eva Lind Grennfelt, Louise Olsson
      First page: 418
      Abstract: Hydrodeoxygenation (HDO) activity of a typical hydrotreating catalyst, sulfided NiMo/γ-Al2O3 for deoxygenation of a fatty acid has been explored in a batch reactor at 54 bar and 320 °C in the presence of contaminants, like phospholipids, which are known to be present in renewable feeds. Oleic acid was used for the investigation. Freshly sulfided catalyst showed a high degree of deoxygenation activity; products were predominantly composed of alkanes (C17 and C18). Experiments with a major phospholipid showed that activity for C17 was greatly reduced while activity to C18 was not altered significantly in the studied conditions. Characterization of the spent catalyst revealed the formation of aluminum phosphate (AlPO4), which affects the active phase dispersion, blocks the active sites, and causes pore blockage. In addition, choline, formed from the decomposition of phospholipid, partially contributes to the observed deactivation. Furthermore, a direct correlation was observed in the accumulation of coke on the catalyst and the amount of phospholipid introduced in the feed. We therefore propose that the reason for the increased deactivation is due to the dual effects of an irreversible change in phase to aluminum phosphate and the formation of choline.
      Citation: Catalysts
      PubDate: 2018-09-25
      DOI: 10.3390/catal8100418
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 419: Novel Bifunctional Mesoporous Catalysts
           

    • Authors: Omar Portilla-Zúñiga, Ángel Sathicq, José Martínez, Hugo Rojas, Eduardo De Geronimo, Rafael Luque, Gustavo P. Romanelli
      First page: 419
      Abstract: In this paper, we report the synthesis of Preyssler heteropolyacids supported on mesoporous alumina in order to obtain materials with acid–base properties. A series of pyrrole derivatives were synthesized using a suitable procedure under solvent-free conditions. Using the alumina-supported material, more complex pyrrole derivatives can be obtained through a tandem one-pot process that involves the formation of 2-amino-3-cyano 4-H-chromenes by a multicomponent reaction and their subsequent conversion to pyrrole using a Paal–Knorr reaction.
      Citation: Catalysts
      PubDate: 2018-09-26
      DOI: 10.3390/catal8100419
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 420: Titanate Nanotube-Supported Au–Rh
           Bimetallic Catalysts: Characterization and Their Catalytic Performances in
           Hydroformylation of Vinyl Acetate

    • Authors: Ya Chen, Penghe Su, Xiaotong Liu, Hongchi Liu, Baolin Zhu, Shoumin Zhang, Weiping Huang
      First page: 420
      Abstract: A series of titanate nanotube-supported metal catalysts (M/TNTs, M = Rh, Au orAu–Rh) were facilely synthesized. The effects of different Au contents, reduction processes and sequence of loading metals on their catalytic performances in the hydroformylation of vinyl acetate were comparatively investigated. The results showed that some Au and Rh formed bimetallic particles. Furthermore, the presence of Au in catalysts could significantly improve the selectivity of reaction for aldehydes. Compared with the monometallic catalysts (Rh0.33/TNTs-1 and Au0.49/TNTs-2), the resultant bimetallic catalysts exhibited significantly higher selectivity for aldehydes as well as higher TOF values in the hydroformylation of vinyl acetate. Among them, Au0.52/Rh0.32/TNTs-12 displayed the best catalytic performance. The corresponding selectivity for aldehydes was as high as 88.67%and the turnover frequency (TOF) reached up to 3500 h−1. In addition, for the reduction of Rh3+ and Au3+ ions, the photo-reduction and ethanol-reduction were the optimal techniques under the present conditions, respectively.
      Citation: Catalysts
      PubDate: 2018-09-26
      DOI: 10.3390/catal8100420
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 421: Theoretical Studies on the Direct Propylene
           Epoxidation Using Gold-Based Catalysts: A Mini-Review

    • Authors: Jingjing Ji, Zheng Lu, Yu Lei, C. Heath Turner
      First page: 421
      Abstract: Direct propylene epoxidation using Au-based catalysts is an important gas-phase reaction and is clearly a promising route for the future industrial production of propylene oxide (PO). For instance, gold nanoparticles or clusters that consist of a small number of atoms demonstrate unique and even unexpected properties, since the high ratio of surface to bulk atoms can provide new reaction pathways with lower activation barriers. Support materials can have a remarkable effect on Au nanoparticles or clusters due to charge transfer. Moreover, Au (or Au-based alloy, such as Au–Pd) can be loaded on supports to form active interfacial sites (or multiple interfaces). Model studies are needed to help probe the underlying mechanistic aspects and identify key factors controlling the activity and selectivity. The current theoretical/computational progress on this system is reviewed with respect to the molecular- and catalyst-level aspects (e.g., first-principles calculations and kinetic modeling) of propylene epoxidation over Au-based catalysts. This includes an analysis of H2 and O2 adsorption, H2O2 (OOH) species formation, epoxidation of propylene into PO, as well as possible byproduct formation. These studies have provided a better understanding of the nature of the active centers and the dominant reaction mechanisms, and thus, could potentially be used to design novel catalysts with improved efficiency.
      Citation: Catalysts
      PubDate: 2018-09-27
      DOI: 10.3390/catal8100421
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 422: Straightforward Design for Phenoxy-Imine
           Catalytic Activity in Ethylene Polymerization: Theoretical Prediction

    • Authors: Pongsakorn Chasing, Phornphimon Maitarad, Hongmin Wu, Dengsong Zhang, Liyi Shi, Vinich Promarak
      First page: 422
      Abstract: The quantitative structure-activity relationship (QSAR) of 18 Ti-phenoxy-imine (FI-Ti)-based catalysts was investigated to clarify the role of the structural properties of the catalysts in polyethylene polymerization activity. The electronic properties of the FI-Ti catalysts were analyzed based on density functional theory with the M06L/6-31G** and LANL2DZ basis functions. The analysis results of the QSAR equation with a genetic algorithm showed that the polyethylene catalytic activity mainly depended on the highest occupied molecular orbital energy level and the total charge of the substituent group on phenylimine ring. The QSAR models showed good predictive ability (R2) and R2 cross validation (R2cv) values of greater than 0.927. The design concept is “head-hat”, where the hats are the phenoxy-imine substituents, and the heads are the transition metals. Thus, for the newly designed series, the phenoxy-imine substituents still remained, while the Ti metal was replaced by Zr or Ni transition metals, entitled FI-Zr and FI-Ni, respectively. Consequently, their polyethylene polymerization activities were predicted based on the obtained QSAR of the FI-Ti models, and it is noteworthy that the FI-Ni metallocene catalysts tend to increase the polyethylene catalytic activity more than that of FI-Zr complexes. Therefore, the new designs of the FI-Ni series are proposed as candidate catalysts for polyethylene polymerization, with their predicted activities in the range of 35,000–48,000 kg(PE)/mol(Cat.)·MPa·h. This combined density functional theory and QSAR analysis is useful and straightforward for molecular design or catalyst screening, especially in industrial research.
      Citation: Catalysts
      PubDate: 2018-09-28
      DOI: 10.3390/catal8100422
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 423: Application of Lecitase® Ultra-Catalyzed
           Hydrolysis to the Kinetic Resolution of (E)-4-phenylbut-3-en-2-yl Esters

    • Authors: Aleksandra Leśniarek, Anna Chojnacka, Witold Gładkowski
      First page: 423
      Abstract: The possibility of using Lecitase® Ultra as a novel alternative biocatalyst for the kinetic resolution of model racemic allyl esters of (E)-4-phenylbut-3-en-3-ol: Acetate (4a) and propionate (4b) through their enantioselective hydrolysis was investigated. Reaction afforded (+)-(R)-alcohol (3) and unreacted (−)-(S)-ester (4a or 4b). Hydrolysis of propionate 4b proceeded with higher enantioselectivity than acetate 4a. (R)-Alcohol (3) with highest enantiomeric excess (93–99%) was obtained at 20–30 °C by hydrolysis of propionate 4b, while the highest optical purity of unreacted substrate was observed for (S)-acetate 4a (ee = 34–56%). The highest enantioselectivity was found for the hydrolysis of propionate 4b catalyzed at 30 °C (E = 38). Reaction carried out at 40 °C significantly lowered enantiomeric excess of produced alcohol 3 and enantioselectivity in resolution. Lecitase® Ultra catalyzed the enantioselective hydrolysis of allyl esters 4a,b according to Kazlauskas’ rule to produce (R)-alcohol 3 and can find application as a novel biocatalyst in the processes of kinetic resolution of racemic allyl esters.
      Citation: Catalysts
      PubDate: 2018-09-28
      DOI: 10.3390/catal8100423
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 424: First-Principles Modeling in Heterogeneous
           Electrocatalysis

    • Authors: Dominic R. Alfonso, De Nyago Tafen, Douglas R. Kauffmann
      First page: 424
      Abstract: The last decade has witnessed tremendous progress in the development of computer simulation based on quantum mechanical description of the interactions between electrons and between electrons and atomic nuclei with electrode potentials taken into account–promoting the possibility to model electrocatalytic reactions. The cornerstone of this development was laid by the widely used computational hydrogen electrode method which involves a posteriori correction of standard constant charge first principles studies in solvent environment. The description of this technique and its contribution to our effort to understand electrocatalytic reactions on the active sites of metal-based nanoparticles are reviewed. The pathways and energetics of the relevant elementary reactions are presented. We also discussed a recent attempt in the literature to account for the inflow and outflow of electrons from the electrode as electrochemical reactions proceed, which has been greatly assisted by the development of density functional theory within the grand canonical framework. Going beyond the computational hydrogen electrode method by explicit incorporation of electrode potential within the calculations permits access to more detailed insights without requiring extra computational burden.
      Citation: Catalysts
      PubDate: 2018-09-28
      DOI: 10.3390/catal8100424
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 425: Catalytic Hydrogenation, Hydrodeoxygenation,
           and Hydrocracking Processes of a Lignin Monomer Model Compound Eugenol
           over Magnetic Ru/C–Fe2O3 and Mechanistic Reaction Microkinetics

    • Authors: Ana Bjelić, Miha Grilc, Sašo Gyergyek, Andraž Kocjan, Darko Makovec, Blaž Likozar
      First page: 425
      Abstract: Conversion of waste lignocellulosic (LC) biomass, a widely-available low-cost feedstock, into value-added biobased chemicals (and biofuels) has been gaining much attention recently. Therefore, the present lignin valorisation study was aimed at developing magnetically-separable highly-active catalysts for hydrodeoxygenation (HDO), also proposing surface chemical kinetics. Five carbonaceous substrate-deposited Ru were synthesised and tested for the HDO of monomer moiety eugenol. Their annealing temperatures differed, specifically between 300 and 750 °C, while one was not subjected to calcination. Experiments revealed the substantial influence of annealing temperature on the product distribution. Namely, fresh nonannealed nanocomposites were not active for hydrogenolysis. By further pretreatment increase, hydrogenation and, exclusively, the deoxygenation of saturated cyclic species, were enhanced, these being more promoted considering rates and yields than commercial carbon-supported ruthenium. Over 80 mol% of 4-propyl-cylohexanol and propyl-cyclohexane could be formed over the samples, treated at 500 and 600 °C, for 100 and 125 min, respectively, under 275 °C and 5 MPa of reactor hydrogen pressure. Interestingly, a notable 4-propyl-phenol amount was produced upon 750 °C pretreating. The intrinsic microkinetic model, developed previously, was applied to determine relevant turnover parameters. Calculated modelling results indicated a 47- and 10-fold greater demethoxylation and dehydroxylation mechanism ability upon the reheatingpreheating at 600 °C in comparison to industrial (heterogeneous) Ru/C.
      Citation: Catalysts
      PubDate: 2018-09-28
      DOI: 10.3390/catal8100425
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 426: Significantly Enhanced Aqueous Cr(VI)
           Removal Performance of Bi/ZnO Nanocomposites via Synergistic Effect of
           Adsorption and SPR-Promoted Visible Light Photoreduction

    • Authors: Xiaoya Yuan, Zijuan Feng, Jianjun Zhao, Jiawei Niu, Jiasen Liu, Dong Peng, Xin Cheng
      First page: 426
      Abstract: Bismuth nanoparticles (BiNPs) and Zinc Oxide photocatalysts (BiNPs/ZnO) with different Bi loadings were successfully prepared via a facile chemical method. Their morphology and structure were thoroughly characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), UV-Vis (Ultraviolet-Visible) diffuse reflectance spectroscopy (DRS), photoluminescence spectra (PL), and electrochemical impedance spectroscopy (EIS). The results showed that a modification of hexagonal wurtzite-phase ZnO nanoparticles with Bi is achievable with an intimate interfacial interaction within its composites. The performance of the photocatalytic Cr(VI) removal under visible light irradiation indicated that BiNPs/ZnO exhibited a superior removal performance to bare ZnO, Bi, and the counterpart sample prepared using a physical mixing method. The excellent performance of the BiNPs/ZnO photocatalysts could be ascribed to the synergistic effect between the considerable physical Cr (VI) adsorption and enhanced absorption intensity in the visible light region, due to the surface plasmon resonance (SPR) as well as the effective transfer and separation of the photogenerated charge carriers at the interface.
      Citation: Catalysts
      PubDate: 2018-09-29
      DOI: 10.3390/catal8100426
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 427: Effect of Residual Na+ on the Combustion of
           Methane over Co3O4 Bulk Catalysts Prepared by Precipitation

    • Authors: Andoni Choya, Beatriz de Rivas, Jose Ignacio Gutiérrez-Ortiz, Rubén López-Fonseca
      First page: 427
      Abstract: The effect of the presence of residual sodium (0.4 %wt) over a Co3O4 bulk catalyst for methane combustion was studied. Two samples, with and without residual sodium, were synthesized by precipitation and thoroughly characterised by X-ray diffraction (XRD), N2 physisorption, Wavelength Dispersive X-ray Fluorescence (WDXRF), temperature-programmed reduction with hydrogen followed by temperature-programmed reduction with oxygen (H2-TPR/O2-TPO), temperature-programmed reaction with methane (CH4-TPRe), ultraviolet–visible–near-infrared diffuse reflectance spectroscopy (UV-vis-NIR DRS), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). It was found that during calcination, a fraction of the sodium atoms initially deposited on the surface diffused and migrated into the spinel lattice, inducing a distortion that improved its textural and structural properties. However, surface sodium had an overall negative impact on the catalytic activity. It led to a reduction of surface Co3+ ions in favour of Co2+, thus ultimately decreasing the Co3+/Co2+ molar ratio (from 1.96 to 1.20) and decreasing the amount and mobility of active lattice oxygen species. As a result, the catalyst with residual sodium (T90 = 545 °C) was notably less active than its clean counterpart (T90 = 500 °C). All of this outlined the significance of a proper washing when synthesizing Co3O4 catalyst using a sodium salt as the precipitating agent.
      Citation: Catalysts
      PubDate: 2018-09-29
      DOI: 10.3390/catal8100427
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 428: Alkanethiolate-Capped Palladium
           Nanoparticles for Regio- and Stereoselective Hydrogenation of Allenes

    • Authors: Ting-An Chen, Young-Seok Shon
      First page: 428
      Abstract: Colloidal Pd nanoparticles capped with octanethiolate ligands have previously shown an excellent selectivity toward the mono-hydrogenation of both isolated and conjugated dienes to internal alkenes. This paper reports an efficient stereoselective mono-hydrogenation of cumulated dienes (allenes) to either Z or E olefinic isomers, depending on the substitution pattern around C=C bonds. Kinetic studies indicate that the reaction progresses through the hydrogenation of less hindered C=C bonds to produce internal Z olefinic isomers. In the cases of di-substitued olefinic products, this initial hydrogenation step is followed by the subsequent isomerization of Z to E isomers. In contrast, the slow isomerization of Z to E isomers for tri-substituted olefinic products results in the preservation of Z stereochemistry. The high selectivity of Pd nanoparticles averting an additional hydrogenation is steered from the controlled electronic and geometric properties of the Pd surface, which are the result of thiolate-induced partial poisoning and surface crowding, respectively. The high activity of colloidal Pd nanoparticle catalysts allows the reactions to be completed at room temperature and atmospheric pressure.
      Citation: Catalysts
      PubDate: 2018-09-29
      DOI: 10.3390/catal8100428
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 429: Nanoplasmon–Semiconductor Hybrid for
           Interface Catalysis

    • Authors: Jingang Wang, Naixing Feng, Ying Sun, Xijiao Mu
      First page: 429
      Abstract: We firstly, in this review, introduce the optical properties of plasmonic metals, and then focus on introducing the unique optical properties of the noble metal–metal-oxide hybrid system by revealing the physical mechanism of plasmon–exciton interaction, which was confirmed by theoretical calculations and experimental investigations. With this noble metal–metal-oxide hybrid system, plasmonic nanostructure–semiconductor exciton coupling interactions for interface catalysis has been analyzed in detail. This review can provide a deeper understanding of the physical mechanism of exciton–plasmon interactions in surface catalysis reactions.
      Citation: Catalysts
      PubDate: 2018-09-29
      DOI: 10.3390/catal8100429
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 430: High Pressure Photoreduction of CO2: Effect
           

    • Authors: Elnaz Bahadori, Antonio Tripodi, Alberto Villa, Carlo Pirola, Laura Prati, Gianguido Ramis, Ilenia Rossetti
      First page: 430
      Abstract: The photoreduction of CO2 is an intriguing process which allows the synthesis of fuels and chemicals. One of the limitations for CO2 photoreduction in the liquid phase is its low solubility in water. This point has been here addressed by designing a fully innovative pressurized photoreactor, allowing operation up to 20 bar and applied to improve the productivity of this very challenging process. The photoreduction of CO2 in the liquid phase was performed using commercial TiO2 (Evonink P25), TiO2 obtained by flame spray pyrolysis (FSP) and gold doped P25 (0.2 wt% Au-P25) in the presence of Na2SO3 as hole scavenger (HS). The different reaction parameters (catalyst concentration, pH and amount of HS) have been addressed. The products in liquid phase were mainly formic acid and formaldehyde. Moreover, for longer reaction time and with total consumption of HS, gas phase products formed (H2 and CO) after accumulation of significant number of organic compounds in the liquid phase, due to their consecutive photoreforming. Enhanced CO2 solubility in water was achieved by adding a base (pH = 12–14). In basic environment, CO2 formed carbonates which further reduced to formaldehyde and formic acid and consequently formed CO/CO2 + H2 in the gas phase through photoreforming. The deposition of small Au nanoparticles (3–5 nm) (NPs) onto TiO2 was found to quantitatively influence the products distribution and increase the selectivity towards gas phase products. Significant energy storage in form of different products has been achieved with respect to literature results.
      Citation: Catalysts
      PubDate: 2018-09-30
      DOI: 10.3390/catal8100430
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 431: Selective Benzyl Alcohol Oxidation over Pd
           Catalysts

    • Authors: Carine Edith Chan-Thaw, Aditya Savara, Alberto Villa
      First page: 431
      Abstract: In the last decades, the selective liquid phase oxidation of alcohols to the corresponding carbonyl compounds has been a subject of growing interest. Research has focused on green methods that use “clean” oxidants such as O2 in combination with supported metal nanoparticles as the catalyst. Among the alcohols, benzyl alcohol is one of the most studied substrates. Indeed, benzyl alcohol can be converted to benzaldehyde, largely for use in the pharmaceutical and agricultural industries. This conversion serves as model reaction in testing new potential catalysts, that can then be applied to other systems. Pd based catalysts have been extensively studied as active catalytic metals for alcohol oxidation for their high activity and selectivity to the corresponding aldehyde. Several catalytic materials obtained by careful control of the morphology of Pd nanoparticles, (including bimetallic systems) and by tuning the support properties have been developed. Moreover, reaction conditions, including solvent, temperature, pressure and alcohol concentration have been investigated to tune the selectivity to the desired products. Different reaction mechanisms and microkinetic models have been proposed. The aim of this review is to provide a critical description of the recent advances on Pd catalyzed benzyl alcohol oxidation.
      Citation: Catalysts
      PubDate: 2018-09-30
      DOI: 10.3390/catal8100431
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 432: A Novel Method for the Prediction of Erosion
           Evolution Process Based on Dynamic Mesh and Its Applications

    • Authors: Yunshan Dong, Zongliang Qiao, Fengqi Si, Bo Zhang, Cong Yu, Xiaoming Jiang
      First page: 432
      Abstract: Particle erosion is a commonly occurring phenomenon, and it plays a significantly important role in service life. However, few simulations have replicated erosion, especially the detailed evolution process. To address this complex issue, a new method for establishing the solution of the erosion evolution process was developed. The approach is introduced with the erosion model and the dynamic mesh. The erosion model was applied to estimate the material removal of erosion, and the dynamic mesh technology was used to demonstrate the surface profile of erosion. Then, this method was applied to solve a typical case—the erosion surface deformation and the expiry period of an economizer bank in coal-fired power plants. The mathematical models were set up, including gas motion, particle motion, particle-wall collision, and erosion. Such models were solved by computational fluid dynamics (CFD) software (ANSYS FLUENT), which describes the evolution process of erosion based on the dynamic mesh. The results indicate that: (1) the prediction of the erosion profile calculated by the dynamic mesh is in good agreement with that on-site; (2) the global/local erosion loss and the maximum erosion depth is linearly related to the working time at the earlier stage, but the growth of the maximum erosion depth slows down gradually in the later stage; (3) the reason for slowing down is that the collision point trajectory moves along the increasing direction of the absolute value of θ as time increases; and (4) the expiry period is shortened as the ash diameter increases.
      Citation: Catalysts
      PubDate: 2018-09-30
      DOI: 10.3390/catal8100432
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 433: Copper-Catalyzed Synthesis, Bio-Evaluation,
           and in Silico Studies of 2-Aryl-N-Alkylbenzimidazoles as Neuroprotective
           Agents

    • Authors: Yun-Xin Yao, Nan-Nan Jia, Ya-Nan Cao, Xing-Xiu Chen, Feng Gao, Xiao-Xia Liang
      First page: 433
      Abstract: 2-aryl-N-alkylbenzimidazole derivatives synthesized by CuI/PPh3 promoted direct coupling of N-alkylbenzimidazoles with aryl bromides. In vitro neurotoxicities of 20 compounds were evaluated, and the neuroprotective abilities of low-neurotoxic compounds (3b, 3g, 3h, 3i, 3j, 3k, 3o, 3q, 3s and 3t) were investigated against toxicity induced by 1-methyl-4-phenylpyridinium ion (MPP+) in SH-SY5Y neuronal cells. In silico studies revealed that compound 3g could have molecule docking with the following proteins: the bone morphogenetic protein receptor type 1B (BMPR1B), human cytochrome P450 1B1(CYP1B1), Metabotropic glutamate receptor 7 (GRM7), histone deacetylase 6 (HDAC6), 5-hydroxytryptamine receptor 5A (HTR5A), human topoisomerase II beta (TOP2B). A molecular docking simulation of model compound 3g and model protein CYP1B1 has been shown.
      Citation: Catalysts
      PubDate: 2018-09-30
      DOI: 10.3390/catal8100433
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 434: Fluorescein Diacetate Hydrolysis Using the
           Whole Biofilm as a Sensitive Tool to Evaluate the Physiological State of
           Immobilized Bacterial Cells

    • Authors: Anna Dzionek, Jolanta Dzik, Danuta Wojcieszyńska, Urszula Guzik
      First page: 434
      Abstract: Due to the increasing interest and the use of immobilized biocatalysts in bioremediation studies, there is a need for the development of an assay for quick and reliable measurements of their overall enzymatic activity. Fluorescein diacetate (FDA) hydrolysis is a widely used assay for measuring total enzymatic activity (TEA) in various environmental samples or in monoculture researches. However, standard FDA assays for TEA measurements in immobilized samples include performing an assay on cells detached from the carrier. This causes an error, because it is not possible to release all cells from the carrier without affecting their metabolic activity. In this study, we developed and optimized a procedure for TEA quantification in the whole biofilm formed on the carrier without disturbing it. The optimized method involves pre-incubation of immobilized carrier in phosphate buffer (pH 7.6) on the orbital shaker for 15 min, slow injection of FDA directly into the middle of the immobilized carrier, and incubation on the orbital shaker (130 rpm, 30 °C) for 1 h. Biofilm dry mass was obtained by comparing the dried weight of the immobilized carrier with that of the unimmobilized carrier. The improved protocol provides a simple, quick, and more reliable quantification of TEA during the development of immobilized biocatalysts compared to the original method.
      Citation: Catalysts
      PubDate: 2018-10-02
      DOI: 10.3390/catal8100434
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 435: Trimetallic Ni-Based Catalysts over
           Gadolinia-Doped Ceria for Green Fuel Production

    • Authors: Patrizia Frontera, Anastasia Macario, Angela Malara, Saveria Santangelo, Claudia Triolo, Fortunato Crea, Pierluigi Antonucci
      First page: 435
      Abstract: The present work concerns the characterization of trimetallic nickel catalysts, NiMoRe (Nickel/Molybdenum/Rhenium), NiMoCu (Nickel/Molybdenum/Copper) and NiMoCo (Nickel/Molybdenum/Cobalt), supported on gadolinia-doped ceria and the evaluation of their catalytic performance in the auto-thermal reforming of ethanol to hydrogen. Catalysts have been prepared by wet impregnation and characterized by XRD, SEM-EDX, TG-DSC, TEM, CHNS, H2-TPR and micro-Raman spectroscopy. The resistance of Ni-alloy catalysts to the carbon deposition and sulfur poisoning has been studied. All catalysts show a similar behavior in the auto-thermal reforming reaction: 100% of ethanol conversion and high selectivity to syngas products, up to 77 vol.%. At 800 °C the coke deposition is very low (less than 0.34 wt%). Sulfur content affects the selectivity and the activity of the catalysts, especially towards the coke formation: high sulfur content promotes the ethylene formation, therefore the amount of coke deposited on spent catalyst increases. NiMoCu seems to be the trimetallic catalyst less sensitive to this aspect.
      Citation: Catalysts
      PubDate: 2018-10-02
      DOI: 10.3390/catal8100435
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 436: Study of Chemical and Morphological
           Transformations during Ni2Mo3N Synthesis via an Oxide Precursor Nitration
           Route

    • Authors: Denis V. Leybo, Dmitry I. Arkhipov, Konstantin L. Firestein, Denis V. Kuznetsov
      First page: 436
      Abstract: Chemical and morphological transformations during Ni2Mo3N synthesis were studied in this work. Nitride samples were synthesized from oxide precursors in H2/N2 flow and were analyzed by thermogravimetry, X-ray diffraction analysis, scanning electron microscopy, and energy dispersive X-ray spectroscopy methods. In addition, physical and chemical adsorption properties were studied using low-temperature N2 physisorption and NH3 temperature-programmed desorption. It was shown that nitride formation proceeds through a sequence of phase transformations: NiMoO4 + MoO3 → Ni + NiMo + MoO2 → Ni + NiMo + Mo2N → Ni2Mo3N. The weight changes that were calculated from the proposed reactions were in agreement with the experimental data from thermogravimetry. The morphology of the powder changed from platelets and spheres for the oxide sample, to aggregates of needle-like particles for the intermediate product, to porous particles with an extended surface area for the nitride final product. The obtained results should prove useful for subsequent Ni2Mo3N based catalysts production process optimization.
      Citation: Catalysts
      PubDate: 2018-10-03
      DOI: 10.3390/catal8100436
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 437: Ammonia Plasma-Catalytic Synthesis Using Low
           Melting Point Alloys

    • Authors: Javishk R. Shah, Joshua M. Harrison, Maria L. Carreon
      First page: 437
      Abstract: The Haber-Bosch process has been the commercial benchmark process for ammonia synthesis for more than a century. Plasma-catalytic synthesis for ammonia production is theorized to have a great potential for being a greener alternative to the Haber-Bosch process. However, the underlying reactions for ammonia synthesis still require some detailed study especially for radiofrequency plasmas. Herein, the use of inductively coupled radiofrequency plasma for the synthesis of ammonia when employing Ga, In and their alloys as catalysts is presented. The plasma is characterized using emission spectroscopy and the surface of catalysts using Scanning Electron Microscope. A maximum energy yield of 0.31 g-NH3/kWh and energy cost of 196 MJ/mol is achieved with Ga-In (0.6:0.4 and 0.2:0.8) alloy at 50 W plasma power. Granular nodes are observed on the surface of catalysts indicating the formation of the intermediate GaN.
      Citation: Catalysts
      PubDate: 2018-10-03
      DOI: 10.3390/catal8100437
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 438: The Synergistic Effect of Pyridinic Nitrogen
           and Graphitic Nitrogen of Nitrogen-Doped Graphene Quantum Dots for
           Enhanced TiO2 Nanocomposites’ Photocatalytic Performance

    • Authors: Fei Li, Ming Li, Yi Luo, Ming Li, Xinyu Li, Jiye Zhang, Liang Wang
      First page: 438
      Abstract: In this study, nitrogen-doped graphene quantum dots (N-GQDs) and a TiO2 nanocomposite were synthesized using a simple hydrothermal route. Ammonia water was used as a nitrogen source to prepare the N-GQDs. When optically characterized by UV-vis, N-GQDs reveal stronger absorption peaks in the range of ultraviolet (UV) light than graphene quantum dots (GQDs). In comparison with GQDs/TiO2 and pure TiO2, the N-GQDs/TiO2 have significantly improved photocatalytic performance. In particular, it was found that, when the added amount of ammonia water was 50 mL, the content of pyridinic N and graphitic N were as high as 22.47% and 31.44%, respectively. Most important, the photocatalytic activity of N-GQDs/TiO2-50 was about 95% after 12 min. The results illustrated that pyridinic N and graphitic N play a significant role in photocatalytic performance.
      Citation: Catalysts
      PubDate: 2018-10-04
      DOI: 10.3390/catal8100438
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 439: Catalytic Combustion Characteristics of
           Methane-Air Mixtures in Small-Scale Systems at Elevated Temperatures

    • Authors: Chen, Gao, Xu
      First page: 439
      Abstract: The catalytic combustion characteristics of methane-air mixtures in small-scale systems were investigated at elevated temperatures, with particular emphasis on identifying the main factors that affect formation and removal of combustion-generated pollutants. Computational fluid dynamics simulations were performed using detailed chemical kinetic mechanisms, and more insights were offered into the phenomena occurring in the temperature range where homogeneous and heterogeneous reaction pathways are both important. Reaction engineering analysis was performed to provide an in-depth understanding of how to achieve low emissions of pollutants. Spatial distributions of the major species involved were presented to gain insight into the interplay between the two competing pathways involved. The results indicated that the distribution of oxidized products depends critically on the feed composition, dimension, temperature, and pressure. Small-scale catalytic systems enable low emissions of pollutants even in a high temperature environment, along with high combustion efficiency. The interplay between the two competing pathways via radicals is strong, and the heterogeneous pathway can significantly inhibit the homogeneous pathway. The inhibiting effect also accounts for the low emissions of nitrogen oxides. Almost all of the nitrogen oxides emitted by small-scale catalytic systems are nitric oxide. Catalytic combustion technology can be used to reduce the formation of undesired products, especially pollutant nitrogen oxide gases far below what can be achieved without catalysts. Recommendations for the design of small-scale catalytic systems are provided.
      Citation: Catalysts
      PubDate: 2018-10-06
      DOI: 10.3390/catal8100439
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 440: Strongly Enhancing Photocatalytic Activity
           of TiO2 Thin Films by Multi-Heterojunction Technique

    • Authors: Cheng, Hung, Yu, Yang
      First page: 440
      Abstract: The photocatalysts of immobilized TiO2 film suffer from high carrier recombination loss when compared to its powder form. Although the TiO2 with rutile-anatase mixed phases has higher carrier separation efficiency than those with pure anatase or rutile phase, the single junction of anatase/rutile cannot avoid the recombination of separated carriers at the interface. In this study, we propose a TiO2/SnO2/Ni multi-heterojunction structure which incorporates both Schottky contact and staggered band alignment to reduce the carrier recombination loss. The low carrier recombination rate of TiO2 film in TiO2/SnO2/Ni multi-heterojunction structure was verified by its low photoluminescence intensity. The faster degradation of methylene blue for TiO2/SnO2/Ni multi-junctions than for the other fabricated structures, which means that the TiO2 films grown on the SnO2/Ni/Ti coated glass have a much higher photocatalytic activity than those grown on the blank glass, SnO2-coated and Ni/Ti-coated glasses, demonstrated its higher performance of photogenerated carrier separation.
      Citation: Catalysts
      PubDate: 2018-10-06
      DOI: 10.3390/catal8100440
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 441: Experimental Study on the Effect of Hydrogen
           Sulfide on High-Temperature Proton Exchange Membrane Fuel Cells by Using
           Electrochemical Impedance Spectroscopy

    • Authors: Ren-Jun Kang, Yong-Song Chen
      First page: 441
      Abstract: When the fuel supplied to a high-temperature proton exchange membrane fuel cell (HT-PEMFC) is produced by hydrocarbon formation, hydrogen sulfide (H2S) may appear, resulting in decreased cell performance and durability. To study the effects of H2S on the performance and durability of the HT-PEMFC, a series of experiments was conducted. In the first step, the effects of polyvinylidene fluoride (PVDF) and platinum loading on cell performance were investigated and discussed under pure hydrogen operation conditions. Optimal PVDF and platinum compositions in the catalyst layer are suggested. Then, the effect of H2S on membrane electrode assembly (MEA) performance with various platinum loadings was investigated by supplying hydrogen containing 5.2 ppm of H2S to the anode of the MEA. An electrochemical impedance spectroscope was employed to measure the impedance of the MEAs under various operating conditions. Finally, degradation of the MEA when supplied with hydrogen containing 5.2 ppm of H2S was analyzed and discussed. The results suggest that the performance of an MEA with 0.7 mg Pt cm−2 and 10% PVDF can be recovered by supplying pure hydrogen. The rate of voltage decrease is around 300 μV h−1 in the presence of H2S.
      Citation: Catalysts
      PubDate: 2018-10-09
      DOI: 10.3390/catal8100441
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 442: Catalysts for the Controlled Polymerization
           of Conjugated Dienes

    • Authors: Marc Visseaux
      First page: 442
      Abstract: Since its first discovery at the beginning of the 1960s […] 
      Citation: Catalysts
      PubDate: 2018-10-09
      DOI: 10.3390/catal8100442
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 443: Novel Magnetically-Recyclable,
           Nitrogen-Doped Fe3O4@Pd NPs for Suzuki–Miyaura Coupling and Their
           Application in the Synthesis of Crizotinib

    • Authors: Kai Zheng, Chao Shen, Jun Qiao, Jianying Tong, Jianzhong Jin, Pengfei Zhang
      First page: 443
      Abstract: Novel magnetically recyclable Fe3O4@Pd nanoparticles (NPs) were favorably synthesized by fixing palladium on the surface of nitrogen-doped magnetic nanocomposites. These catalysts were fully characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), thermogravimetric analysis (TG), and X-ray photoelectron spectroscopy (XPS). The prepared catalyst exhibited good catalytic activity for Suzuki–Miyaura coupling reactions of aryl or heteroaryl halides (I, Br, Cl) with arylboronic acids. These as-prepared catalysts could be readily isolated from the reaction liquid by an external magnet and reused at least ten times with excellent yields achieved. In addition, using this protocol, the marketed drug crizotinib (anti-tumor) could be easily synthesized.
      Citation: Catalysts
      PubDate: 2018-10-10
      DOI: 10.3390/catal8100443
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 444: Theoretical Study on the Quantum Capacitance
           Origin of Graphene Cathodes in Lithium Ion Capacitors

    • Authors: Fangyuan Su, Li Huo, Qingqiang Kong, Lijing Xie, Chengmeng Chen
      First page: 444
      Abstract: Quantum capacitance (QC) is a very important character of the graphene cathode in lithium ion capacitors (LIC), which is a novel kind of electrochemical energy conversion and storage device. However, the QC electronic origin of the graphene cathode, which will affect the electrochemical reaction at the electrode/electrolyte interface, is still unclear. In this article, the QC of various kinds of graphene cathode is investigated systematically by DFT calculation. It was found that the value and origin of QC strongly depend on the defects and alien atoms of graphene. Graphene with pentagon defects possesses a higher QC than pristine graphene due to the contribution from the electronic states localized at the carbon pentagon. The introduction of graphitic B can contribute to QC, while graphitic N and P does not work in the voltage range of the LIC cathode. Single vacant defect graphene and pyrrolic N-doped graphene demonstrate very high QC due to the presence of states associated with the σ orbital of unbonded carbon atoms. However, pyridinic graphene shows an even higher QC because of the states from the N atom. For the residual O in graphene, its QC mainly originated from the pz states of carbon atoms and the effect of O, especially the O in bridged oxygen functional group (–COC–), is very limited. These results provide new insight into further study of the catalytic behavior and the design of a high performance graphene cathode for LIC.
      Citation: Catalysts
      PubDate: 2018-10-11
      DOI: 10.3390/catal8100444
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 445: Kinetic and Mechanistic Study on Catalytic
           Decomposition of Hydrogen Peroxide on Carbon-Nanodots/Graphitic Carbon
           Nitride Composite

    • Authors: Zhongda Liu, Qiumiao Shen, Chunsun Zhou, Lijuan Fang, Miao Yang, Tao Xia
      First page: 445
      Abstract: The metal-free CDots/g-C3N4 composite, normally used as the photocatalyst in H2 generation and organic degradation, can be also applied as an environmental catalyst by in-situ production of strong oxidant hydroxyl radical (HO·) via catalytically decomposition of hydrogen peroxide (H2O2) without light irradiation. In this work, CDots/g-C3N4 composite was synthesized via an electrochemical method preparing CDots followed by the thermal polymerization of urea. Transmission electron microscopy (TEM), X-Ray diffraction (XRD), Fourier Transform Infrared (FTIR), N2 adsorption/desorption isotherm and pore width distribution were carried out for characterization. The intrinsic catalytic performance, including kinetics and thermodynamic, was studied in terms of catalytic decomposition of H2O2 without light irradiation. The second-order rate constant of the reaction was calculated to be (1.42 ± 0.07) × 10−9 m·s−1 and the activation energy was calculated to be (29.05 ± 0.80) kJ·mol−1. Tris(hydroxymethyl) aminomethane (Tris) was selected to probe the produced HO· during the decomposing of H2O2 as well as to buffer the pH of the solution. The composite was shown to be base-catalyzed and the optimal performance was achieved at pH 8.0. A detailed mechanism involving the adsorb-catalyze double reaction site was proposed. Overall, CDots/g-C3N4 composite can be further applied in advanced oxidation technology in the presence of H2O2 and the instinct dynamics and the mechanism can be referred to further applications in related fields.
      Citation: Catalysts
      PubDate: 2018-10-11
      DOI: 10.3390/catal8100445
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 446: Effect of Calcination Atmosphere and
           Temperature on the Hydrogenolysis Activity and Selectivity of Copper-Zinc
           Catalysts

    • Authors: Oleg Kikhtyanin, Violetta Pospelova, Jaroslav Aubrecht, Miloslav Lhotka, David Kubička
      First page: 446
      Abstract: A series of CuZn catalysts with a Cu/Zn ratio of 1.6 was prepared by the calcination of a single precursor, CuZn-P consisting of an equimolar mixture of aurichalcite and zincian malachite, in three different calcination atmospheres (air, nitrogen, and hydrogen) at three temperatures (220, 350, and 500 °C). All catalysts were characterized by XRD and N2-physisorption to assess their phase composition, crystallite sizes and textural properties and tested in dimethyl adipate (DMA) hydrogenolysis in a batch reactor at 220 °C and 10 MPa H2. The XRD examination of these catalysts proved that both parameters, calcination temperature and atmosphere, affected the resulting phase composition of the catalysts as well as their crystallite sizes. In an oxidizing atmosphere, CuO and ZnO in intimate contact prevailed whereas in inert or reducing atmosphere both oxides were accompanied by Cu2O and Cu. The crystallite size of Cu2O and Cu was larger than the size of CuO and ZnO thus indicating a less intimate contact between the Cu-phases and ZnO in catalysts calcined in nitrogen and hydrogen. Catalysts prepared by calcination at 220 °C and CuZn catalyst calcined in the air at 350 °C significantly outperformed the other catalysts in DMA hydrogenolysis with a 59–78% conversion due to the small crystallite size and intimate contact between the CuO and ZnO phases prior to catalyst reduction. Despite the low DMA conversion (<30%), transesterification products were the main reaction products with overall selectivities of >80% over the catalysts calcined in nitrogen or hydrogen at least at 350 °C. The obvious change in the preferred reaction pathway because of the atmosphere calcination and temperature shows that there are different active sites responsible for hydrogenolysis and transesterification and that their relative distribution has changed.
      Citation: Catalysts
      PubDate: 2018-10-11
      DOI: 10.3390/catal8100446
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 447: Ag-Based Catalysts in Heterogeneous
           Selective Oxidation of Alcohols: A Review

    • Authors: Viktoriia V. Torbina, Andrei A. Vodyankin, Sergey Ten, Grigory V. Mamontov, Mikhail A. Salaev, Vladimir I. Sobolev, Olga V. Vodyankina
      First page: 447
      Abstract: Alcohols (bioalcohols) is a class of chemicals that are used as a feedstock for the manufacturing of a large number of valuable intermediates in industrially important processes. Currently, sustainable technologies for selective conversion of alcohols utilize “green” oxidants, mainly, ambient air or oxygen. Due to the high affinity of oxygen towards silver, the latter serves as an active component of supported heterogeneous catalysts. In this review, we consider Ag-based catalysts that participate in gas- or liquid-phase oxidation of alcohols. Oxidation of methanol, ethanol, ethylene glycol, propylene glycol, glycerol, benzyl and allyl alcohols is mostly considered. A particular attention is paid to selective photooxidation of alcohols over Ag-based catalysts. We discuss the catalyst composition in terms of (1) the state of the active component, (2) the nature of the substrate, (3) support nature, and (4) the strength of the metal–support interactions.
      Citation: Catalysts
      PubDate: 2018-10-11
      DOI: 10.3390/catal8100447
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 448: Rh/CeO2 Thin Catalytic Layer Deposition on
           Alumina Foams: Catalytic Performance and Controlling Regimes in Biogas
           Reforming Processes

    • Authors: Cristina Italiano, Muhammad Arsalan Ashraf, Lidia Pino, Carmen Williana Moncada Quintero, Stefania Specchia, Antonio Vita
      First page: 448
      Abstract: The application of ceramic foams as structured catalyst supports is clearly expanding due to faster mass/heat transfer and higher contact efficiency than honeycomb monoliths and, mainly, packed beds. In this paper, alumina open-cell foams (OCFs) with different pore density (20, 30 and 40 ppi) were coated with Rh/CeO2 catalyst via a two steps synthesis method involving: (i) the solution combustion synthesis (SCS) to in-situ deposit the CeO2 carrier and (ii) the wet impregnation (WI) of the Rh active phase. The catalytic coatings were characterized in terms of morphology and adhesion properties by SEM/EDX analysis and ultrasounds test. Permeability and form coefficient were derived from pressure drop data. Catalytic performance was evaluated towards biogas Steam Reforming (SR) and Oxy-Steam Reforming (OSR) processes at atmospheric pressure by varying temperature (800–900 °C) and space velocity (35,000–140,000 NmL·g−1·h−1). Characteristics time analysis and dimensionless numbers were calculated to identify the controlling regime. Stability tests were performed for both SR and OSR over 200 h of time-on-stream (TOS) through consecutive start-up and shut-down cycles. As a result, homogenous, thin and high-resistance catalytic layers were in situ deposited on foam struts. All structured catalysts showed high activity, following the order 20 ppi < 30 ppi ≈ 40 ppi. External interphase (gas-solid) and external diffusion can be improved by reducing the pore diameter of the OCF structures. Anderson criterion revealed the absence of internal heat transfer resistances, as well as Damköhler and Weisz-Prater numbers excluded any internal mass transfer controlling regime, mainly due to thin coating thickness provided by the SCS method. Good stability was observed over 200 h of TOS for both SR and OSR processes.
      Citation: Catalysts
      PubDate: 2018-10-11
      DOI: 10.3390/catal8100448
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 449: Synthesis and Regeneration of Nickel-Based
           Catalysts for Hydrodeoxygenation of Beech Wood Fast Pyrolysis Bio-Oil

    • Authors: Caroline Carriel Schmitt, María Belén Gagliardi Reolon, Michael Zimmermann, Klaus Raffelt, Jan-Dierk Grunwaldt, Nicolaus Dahmen
      First page: 449
      Abstract: Four nickel-based catalysts are synthesized by wet impregnation and evaluated for the hydrotreatment/hydrodeoxygenation of beech wood fast-pyrolysis bio-oil. Parameters such as elemental analysis, pH value, and water content, as well as the heating value of the upgraded bio-oils are considered for the evaluation of the catalysts’ activity and catalyst reuse in cycles of hydrodeoxygenation after regeneration. The reduction temperature, selectivity and hydrogen consumption are distinct among them, although all catalysts tested produce upgraded bio-oils with reduced oxygen concentration, lower water content and higher energy density. Ni/SiO2, in particular, can remove more than 50% of the oxygen content and reduce the water content by more than 80%, with low coke and gas formation. The evaluation over four consecutive hydrotreatment reactions and catalyst regeneration shows a slightly reduced hydrodeoxygenation activity of Ni/SiO2, mainly due to deactivation caused by sintering and adsorption of poisoning substances, such as sulfur. Following the fourth catalyst reuse, the upgraded bio-oil shows 43% less oxygen in comparison to the feedstock and properties comparable to the upgraded bio-oil obtained with the fresh catalyst. Hence, nickel-based catalysts are promising for improving hardwood fast-pyrolysis bio-oil properties, especially monometallic nickel catalysts supported on silica.
      Citation: Catalysts
      PubDate: 2018-10-12
      DOI: 10.3390/catal8100449
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 450: H2 Thermal Desorption Spectra on Pt(111): A
           Density Functional Theory and Kinetic Monte Carlo Simulation Study

    • Authors: Caoming Yu, Fang Wang, Yunlei Zhang, Leihong Zhao, Botao Teng, Maohong Fan, Xiaona Liu
      First page: 450
      Abstract: Theoretical investigation of the static and kinetic behaviors of H and H2 on metal surface plays a key role in the development of hydrogenation catalysts and new materials with high H2 storage capacity. Based on the density functional theory (DFT) calculation of H and H2 adsorption on Pt(111), H(a) adatom strongly interacts with surface Pt; while H2 weakly adsorbs on Pt(111). H(a) adatoms stably occupy the face-centered cubic sites on Pt(111) which agrees with the experimental LERS observations. By using kinetic Monte Carlo (kMC) simulation, the qualitative effects of the kinetic parameters on the H2 TDS spectra indicate that the H2 desorption peaks shift to the low temperature with increasing pre-exponential factor and decreasing desorption barrier. Simultaneously, the desorption peaks shift downwards and broaden to two peaks with the increase of the lateral interaction energy among H(a) adatoms. Using the kMC simulation based on DFT calculation, the predicted H2 TDS spectra are well consistent with the experimental ones. It unanimously proves that the two peaks of TDS spectra are derived from the lateral interactions among H(a). This work provides the intrinsic kinetics of H(a) and H2 on Pt(111) at an atomic level, and gives insight into the development of hydrogenation catalysts.
      Citation: Catalysts
      PubDate: 2018-10-12
      DOI: 10.3390/catal8100450
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 451: Rapid Suzuki-Miyaura Couplings with ppm
           Level of Palladium Catalyst in a High-Pressure and High-Temperature Water
           System

    • Authors: Ikuhiro Nagao, Maya Chatterjee, Hajime Kawanami
      First page: 451
      Abstract: A microflow process was developed for Suzuki-Miyaura Couplings (SMCs) in high-pressure and high-temperature (HPHT) water with a small amount of ethanol. Using this approach, an efficient SMC between 4-methylphenylboronic acid and iodobenzene as a model reaction was demonstrated in water medium, in the presence of ppm order PdCl2/NaOH as a simple catalyst/base without any additional ligands, affording the desired products in good yields within <25 s of residence time. The strategy developed for SMCs also demonstrated an aspect of separation by quantitative tracing of 0.1 ppm contaminated Pd with the product, which might be attributed to the low catalyst amount along with the reaction conditions, as well as the immediate membrane separation applied in the sequence.
      Citation: Catalysts
      PubDate: 2018-10-12
      DOI: 10.3390/catal8100451
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 452: Catalytic Oxidation of Benzyl Alcohol Using
           

    • Authors: Sameerah I. Al-Saeedi, Laila H. Abdel-Rahman, Ahmed M. Abu-Dief, Shimaa M. Abdel-Fatah, Tawfiq M. Alotaibi, Ali M. Alsalme, Ayman Nafady
      First page: 452
      Abstract: In this work, nanosized Cu and Ni Schiff-base complexes, namely ahpvCu, ahpnbCu, and ahpvNi, incorporating imine ligands derived from the condensation of 2-amino-3-hydroxypyridine, with either 3-methoxysalicylaldehyde (ahpv) or 4-nitrobenzaldehyde (ahpnb), were synthesized using sonochemical approach. The structure and properties of the new ligands and their complexes with Ni(II) and Cu(II) were determined via infrared (IR), nuclear magnetic resonance (NMR), electronic spectra (UV-Vis), elemental analysis (CHN), thermal gravimetric analysis (TGA), molar conductivity (Λm), and magnetic moment (μeff). The combined results revealed the formation of 1:1 (metal: ligand) complexes for ahpvCu and ahpvNi and 1:2 for ahpnbCu. Additionally, CuO and NiO nanoparticles were prepared by calcination of the respective nanosized Cu/Ni complexes at 500 °C, and characterized by powder X-ray diffraction (XRD) and transmission electron microscopy (TEM). Significantly, the as-prepared nanosized Schiff-base Cu/Ni complexes and their oxides showed remarkable catalytic activity towards the selective oxidation of benzyl alcohol (BzOH) in aqueous H2O2/ dimethylsulfoxide (DMSO) solution. Thus, catalytic oxidation of BzOH to benzaldehyde (BzH) using both ahpvCu complex and CuO nanoparticles in H2O2/DMSO media at 70 °C for 2 h yielded 94% and 98% BzH, respectively, with 100% selectivity.
      Citation: Catalysts
      PubDate: 2018-10-13
      DOI: 10.3390/catal8100452
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 453: SnO2 Composite Films for Enhanced
           Photocatalytic Activities

    • Authors: Ke Han, Xue-Lei Peng, Fang Li, Ming-Ming Yao
      First page: 453
      Abstract: As a new type of promising semiconductor photocatalyst, SnO2 cannot be widely applied due to its low utilization efficiency to visible light and swift recombination of photogenerated electrons and holes. These drawbacks were effectively overcome by preparing the B/Ag/F tridoped SnO2-ZnO composite films using the simple sol–gel method. The degradation of the methyl green and formaldehyde solutions was used to value the photocatalytic activity of the samples. Photoluminescence (PL) spectra and the UV–Vis absorption spectroscopy results of the samples illustrated that the B/Ag/F tridoped SnO2-ZnO composite film not only improved the lifetime of the charge carriers, but also enhanced their visible light absorption. The X-ray diffraction (XRD) results showed that the crystalline SnO2 was in the structure of rutile. As exhibited in the BET surface area results, the specific surface area of pure SnO2 was 19.9 m2g−1, while that of the B/Ag/F tridoped SnO2-ZnO was 85.3 m2g−1. Compared to pure SnO2, SnO2-ZnO, or the mono- or di-doped SnO2-ZnO films, the B/Ag/F tridoped SnO2-ZnO composite film had the highest photocatalytic activity.
      Citation: Catalysts
      PubDate: 2018-10-14
      DOI: 10.3390/catal8100453
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 454: Hydrogen Oxidation on Ni-Based
           Electrocatalysts: The Effect of Metal Doping

    • Authors: Elena S. Davydova, Jérémie Zaffran, Kapil Dhaka, Maytal Caspary Toroker, Dario R. Dekel
      First page: 454
      Abstract: Carbon supported nanoparticles of monometallic Ni catalyst and binary Ni-Transition Metal (Ni-TM/C) electrocatalytic composites were synthesized via the chemical reduction method, where TM stands for the doping elements Fe, Co, and Cu. The chemical composition, structure and morphology of the Ni-TM/C materials were characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM) and energy-dispersive X-ray spectroscopy (EDS). The electrochemical properties towards hydrogen oxidation reaction in alkaline medium were studied using the rotating disc electrode and cycling voltammetry methods. A significant role of the TM dopants in the promotion of the hydrogen electrooxidation kinetics of the binary Ni-TM/C materials was revealed. A record-high in exchange current density value of 0.060 mA cm2Ni was measured for Ni3Fe1/C, whereas the monometallic Ni/C counterpart has only shown 0.039 mA cm2Ni. In order to predict the feasibility of the electrocatalysts for hydrogen chemisorption, density functional theory was applied to calculate the hydrogen binding energy and hydroxide binding energy values for bare Ni and Ni3TM1.
      Citation: Catalysts
      PubDate: 2018-10-15
      DOI: 10.3390/catal8100454
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 455: Photoelectrocatalytic vs. Photocatalytic
           Degradation of Organic Water Born Pollutants

    • Authors: Ioannis Papagiannis, Georgia Koutsikou, Zacharias Frontistis, Ioannis Konstantinou, George Avgouropoulos, Dionissios Mantzavinos, Panagiotis Lianos
      First page: 455
      Abstract: The azo dye Basic Blue 41 was subjected to photocatalytic and photoelectrocatalytic degradation using nanopararticulate titania films deposited on either glass slides or Fluorine doped Tin Oxide (FTO) transparent electrodes. The degradation was carried out by irradiating titania films with weak ultraviolet (UVA) radiation. The degradation was faster when using FTO as a titania support even without bias and was further accelerated under forward electric bias. This result was explained by enhanced electron-hole separation even in the case of the unbiased titania/FTO combination. This system for organic material photocatalytic degradation was also successfully applied to the degradation of the anti-inflammatory drug piroxicam, which demonstrated a well distinguished degradation behavior in going from a plain glass support to unbiased and biased FTO. The degradation pathway of piroxicam has been additionally studied using liquid chromatography-accurate mass spectrometry analysis.
      Citation: Catalysts
      PubDate: 2018-10-15
      DOI: 10.3390/catal8100455
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 456: Oligomerization of Butene Mixture over
           NiO/Mesoporous Aluminosilicate Catalyst

    • Authors: Donggun Lee, Hyeona Kim, Young-Kwon Park, Jong-Ki Jeon
      First page: 456
      Abstract: This study is aimed at preparing C8–C16 alkene through oligomerization of a butene mixture using nickel oxide supported on mesoporous aluminosilicate. Mesoporous aluminosilicate with an ordered structure was successfully synthesized from HZSM-5 zeolite by combining a top-down and a bottom-up method. MMZZSM-5 catalyst showed much higher butene conversion and C8–C16 yield in the butene oligomerization reaction than those with HZSM-5. This is attributed to the pore geometry of MMZZSM-5, which is more beneficial for internal diffusion of reactants, reaction intermediates, and products. The ordered channel-like mesopores were maintained after the nickel-loading on MMZZSM-5. The yield for C8–C16 hydrocarbons over NiO/MMZZSM-5 was higher than that of MMZZSM-5 catalyst, which seemed to be due to higher acid strength from a higher ratio of Lewis acid to Brønsted acid. The present study reveals that a mesoporous NiO/MMZZSM-5 catalyst with a large amount of Lewis acid sites is one of the potential catalysts for efficient generation of aviation fuel through the butene oligomerization.
      Citation: Catalysts
      PubDate: 2018-10-16
      DOI: 10.3390/catal8100456
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 457: Ultrasonic-Assisted Synthesis of 2D
           α-Fe2O3@g-C3N4 Composite with Excellent Visible Light Photocatalytic
           Activity

    • Authors: Huoli Zhang, Changxin Zhu, Jianliang Cao, Qingjie Tang, Man Li, Peng Kang, Changliang Shi, Mingjie Ma
      First page: 457
      Abstract: In this study, α-Fe2O3@g-C3N4 photocatalyst was synthesized using an ultrasonic assisted self-assembly preparation method. The α-Fe2O3@g-C3N4 photocatalyst had a stronger optical absorption in the visible light region than pure graphitic carbon nitride (g-C3N4). The Z-Scheme heterojunction between α-Fe2O3 and g-C3N4 significantly inhibited the recombination of electrons and holes. The photocatalytic performances of α-Fe2O3@g-C3N4 photocatalyst were excellent in degradation of Rhodamine B (RhB) under visible light irradiation. The results indicated that 5 wt.% α-Fe2O3/g-C3N4 had the optimal photocatalytic activity because two-dimension (2D) α-Fe2O3 nanosheets can be well-dispersed on the surface of g-C3N4 layers by ultrasonic assisted treatment. A possible photocatalytic mechanism is also discussed.
      Citation: Catalysts
      PubDate: 2018-10-16
      DOI: 10.3390/catal8100457
      Issue No: Vol. 8, No. 10 (2018)
       
  • Catalysts, Vol. 8, Pages 458: Recent Progress in the Transition Metal
           Catalyzed Synthesis of Indoles

    • Authors: Raffaella Mancuso, Renato Dalpozzo
      First page: 458
      Abstract: Indole is the most frequently found heterocyclic core structures in pharmaceuticals, natural products, agrochemicals, dyes and fragrances. For about 150 years, chemists were absorbed in finding new and easier synthetic strategies to build this nucleus. Many books and reviews have been written, but the number of new syntheses that appear in the literature, make necessary continuous updates. This reviews aims to give a comprehensive overview on indole synthesis catalyzed by transition metals appeared in the literature in the years 2016 and 2017.
      Citation: Catalysts
      PubDate: 2018-10-16
      DOI: 10.3390/catal8100458
      Issue No: Vol. 8, No. 10 (2018)
       
 
 
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