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  Subjects -> CHEMISTRY (Total: 849 journals)
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CHEMISTRY (598 journals)                  1 2 3 | Last

Showing 1 - 200 of 735 Journals sorted alphabetically
2D Materials     Hybrid Journal   (Followers: 8)
Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement     Hybrid Journal   (Followers: 26)
ACS Catalysis     Full-text available via subscription   (Followers: 32)
ACS Chemical Neuroscience     Full-text available via subscription   (Followers: 17)
ACS Combinatorial Science     Full-text available via subscription   (Followers: 23)
ACS Macro Letters     Full-text available via subscription   (Followers: 23)
ACS Medicinal Chemistry Letters     Full-text available via subscription   (Followers: 39)
ACS Nano     Full-text available via subscription   (Followers: 227)
ACS Photonics     Full-text available via subscription   (Followers: 11)
ACS Synthetic Biology     Full-text available via subscription   (Followers: 21)
Acta Chemica Iasi     Open Access   (Followers: 2)
Acta Chimica Sinica     Full-text available via subscription   (Followers: 1)
Acta Chimica Slovaca     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: 5)
Acta Scientifica Naturalis     Open Access   (Followers: 2)
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 5)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 7)
Adsorption Science & Technology     Full-text available via subscription   (Followers: 5)
Advanced Functional Materials     Hybrid Journal   (Followers: 50)
Advanced Science Focus     Free   (Followers: 3)
Advances in Chemical Engineering and Science     Open Access   (Followers: 53)
Advances in Chemical Science     Open Access   (Followers: 13)
Advances in Chemistry     Open Access   (Followers: 14)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 18)
Advances in Drug Research     Full-text available via subscription   (Followers: 22)
Advances in Enzyme Research     Open Access   (Followers: 9)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 8)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 15)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 8)
Advances in Materials Physics and Chemistry     Open Access   (Followers: 19)
Advances in Nanoparticles     Open Access   (Followers: 14)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 15)
Advances in Polymer Science     Hybrid Journal   (Followers: 41)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 18)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 19)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 5)
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: 2)
African Journal of Pure and Applied Chemistry     Open Access   (Followers: 7)
Agrokémia és Talajtan     Full-text available via subscription   (Followers: 2)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 3)
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: 14)
American Journal of Chemistry     Open Access   (Followers: 26)
American Journal of Plant Physiology     Open Access   (Followers: 13)
American Mineralogist     Hybrid Journal   (Followers: 13)
Analyst     Full-text available via subscription   (Followers: 38)
Angewandte Chemie     Hybrid Journal   (Followers: 164)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 212)
Annales UMCS, Chemia     Open Access   (Followers: 1)
Annals of Clinical Chemistry and Laboratory Medicine     Open Access   (Followers: 1)
Annual Reports in Computational Chemistry     Full-text available via subscription   (Followers: 3)
Annual Reports Section A (Inorganic Chemistry)     Full-text available via subscription   (Followers: 3)
Annual Reports Section B (Organic Chemistry)     Full-text available via subscription   (Followers: 8)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 12)
Annual Review of Food Science and Technology     Full-text available via subscription   (Followers: 14)
Anti-Infective Agents     Hybrid Journal   (Followers: 3)
Antiviral Chemistry and Chemotherapy     Hybrid Journal  
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 7)
Applied Spectroscopy     Full-text available via subscription   (Followers: 23)
Applied Surface Science     Hybrid Journal   (Followers: 28)
Arabian Journal of Chemistry     Open Access   (Followers: 6)
ARKIVOC     Open Access   (Followers: 2)
Asian Journal of Biochemistry     Open Access   (Followers: 1)
Atomization and Sprays     Full-text available via subscription   (Followers: 3)
Australian Journal of Chemistry     Hybrid Journal   (Followers: 7)
Autophagy     Hybrid Journal   (Followers: 2)
Avances en Quimica     Open Access   (Followers: 1)
Biochemical Pharmacology     Hybrid Journal   (Followers: 10)
Biochemistry     Full-text available via subscription   (Followers: 284)
Biochemistry Insights     Open Access   (Followers: 5)
Biochemistry Research International     Open Access   (Followers: 6)
BioChip Journal     Hybrid Journal  
Bioinorganic Chemistry and Applications     Open Access   (Followers: 9)
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: 1)
Biomacromolecules     Full-text available via subscription   (Followers: 19)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 10)
Biomedical Chromatography     Hybrid Journal   (Followers: 6)
Biomolecular NMR Assignments     Hybrid Journal   (Followers: 3)
BioNanoScience     Partially Free   (Followers: 4)
Bioorganic & Medicinal Chemistry     Hybrid Journal   (Followers: 110)
Bioorganic & Medicinal Chemistry Letters     Hybrid Journal   (Followers: 93)
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: 2)
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: 3)
Carbohydrate Research     Hybrid Journal   (Followers: 26)
Carbon     Hybrid Journal   (Followers: 67)
Catalysis for Sustainable Energy     Open Access   (Followers: 6)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 8)
Catalysis Science and Technology     Free   (Followers: 6)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysts     Open Access   (Followers: 7)
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: 12)
Chemical Bulletin of Kazakh National University     Open Access  
Chemical Communications     Full-text available via subscription   (Followers: 70)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 23)
Chemical Research in Chinese Universities     Hybrid Journal   (Followers: 3)
Chemical Research in Toxicology     Full-text available via subscription   (Followers: 19)
Chemical Reviews     Full-text available via subscription   (Followers: 174)
Chemical Science     Open Access   (Followers: 21)
Chemical Technology     Open Access   (Followers: 16)
Chemical Vapor Deposition     Hybrid Journal   (Followers: 5)
Chemical Week     Full-text available via subscription   (Followers: 8)
Chemie in Unserer Zeit     Hybrid Journal   (Followers: 55)
Chemie-Ingenieur-Technik (Cit)     Hybrid Journal   (Followers: 25)
ChemInform     Hybrid Journal   (Followers: 8)
Chemistry & Biodiversity     Hybrid Journal   (Followers: 6)
Chemistry & Biology     Full-text available via subscription   (Followers: 30)
Chemistry & Industry     Hybrid Journal   (Followers: 5)
Chemistry - A European Journal     Hybrid Journal   (Followers: 150)
Chemistry - An Asian Journal     Hybrid Journal   (Followers: 15)
Chemistry and Materials Research     Open Access   (Followers: 18)
Chemistry Central Journal     Open Access   (Followers: 4)
Chemistry Education Research and Practice     Free   (Followers: 5)
Chemistry in Education     Open Access   (Followers: 9)
Chemistry International     Hybrid Journal   (Followers: 2)
Chemistry Letters     Full-text available via subscription   (Followers: 45)
Chemistry of Materials     Full-text available via subscription   (Followers: 243)
Chemistry of Natural Compounds     Hybrid Journal   (Followers: 9)
Chemistry World     Full-text available via subscription   (Followers: 22)
Chemistry-Didactics-Ecology-Metrology     Open Access  
ChemistryOpen     Open Access   (Followers: 2)
Chemkon - Chemie Konkret, Forum Fuer Unterricht Und Didaktik     Hybrid Journal  
Chemoecology     Hybrid Journal   (Followers: 2)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 15)
Chemosensors     Open Access  
ChemPhysChem     Hybrid Journal   (Followers: 9)
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: 10)
Chromatographia     Hybrid Journal   (Followers: 24)
Chromatography Research International     Open Access   (Followers: 7)
Clay Minerals     Full-text available via subscription   (Followers: 9)
Cogent Chemistry     Open Access  
Colloid and Interface Science Communications     Open Access  
Colloid and Polymer Science     Hybrid Journal   (Followers: 10)
Colloids and Surfaces B: Biointerfaces     Hybrid Journal   (Followers: 8)
Combinatorial Chemistry & High Throughput Screening     Hybrid Journal   (Followers: 3)
Combustion Science and Technology     Hybrid Journal   (Followers: 18)
Comments on Inorganic Chemistry: A Journal of Critical Discussion of the Current Literature     Hybrid Journal   (Followers: 2)
Composite Interfaces     Hybrid Journal   (Followers: 6)
Comprehensive Chemical Kinetics     Full-text available via subscription   (Followers: 2)
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: 9)
Coordination Chemistry Reviews     Full-text available via subscription   (Followers: 2)
Copernican Letters     Open Access  
Critical Reviews in Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 5)
Crystal Structure Theory and Applications     Open Access   (Followers: 3)
CrystEngComm     Full-text available via subscription   (Followers: 11)
Current Catalysis     Hybrid Journal   (Followers: 2)
Current Metabolomics     Hybrid Journal   (Followers: 5)
Current Opinion in Colloid & Interface Science     Hybrid Journal   (Followers: 9)
Current Research in Chemistry     Open Access   (Followers: 8)
Current Science     Open Access   (Followers: 56)
Dalton Transactions     Full-text available via subscription   (Followers: 19)
Detection     Open Access   (Followers: 2)
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  
Doklady Chemistry     Hybrid Journal  
Drying Technology: An International Journal     Hybrid Journal   (Followers: 4)
Eclética Química     Open Access   (Followers: 1)
Ecological Chemistry and Engineering S     Open Access   (Followers: 4)
Ecotoxicology and Environmental Contamination     Open Access  
Educación Química     Open Access   (Followers: 1)
Education for Chemical Engineers     Hybrid Journal   (Followers: 5)
EJNMMI Radiopharmacy and Chemistry     Open Access  
Elements     Full-text available via subscription   (Followers: 2)
Environmental Chemistry     Hybrid Journal   (Followers: 9)
Environmental Chemistry Letters     Hybrid Journal   (Followers: 4)
Environmental Science & Technology Letters     Full-text available via subscription   (Followers: 5)

        1 2 3 | Last

Journal Cover Catalysts
  [SJR: 1.123]   [H-I: 14]   [7 followers]  Follow
    
  This is an Open Access Journal Open Access journal
   ISSN (Online) 2073-4344
   Published by MDPI Homepage  [151 journals]
  • Catalysts, Vol. 7, Pages 193: Chiral Catalyst Deactivation during the
           Asymmetric Hydrogenation of Acetophenone

    • Authors: Jose Ruelas-Leyva, Gustavo Fuentes
      First page: 193
      Abstract: Asymmetric hydrogenation in solution catalyzed by chiral catalysts is a powerful tool to obtain chiral secondary alcohols. It is possible to reach conversions and enantiomeric excesses close to 99%, but that frequently requires the use of non-optimal amounts of catalysts or long reaction times. That is in part caused by the lack of kinetic information needed for the design of large-scale reactors, including few reported details about catalyst deactivation. In this work, we present a kinetic model for the asymmetric hydrogenation in solution of acetophenone, a prochiral substrate, catalyzed by different bisphosphine-diamine Ru complexes. The experimental data was fitted with a first order model that includes first order deactivation of the catalyst and the presence of residual activity. The fit of the experimental data is very good, and an analysis of the kinetic and deactivation parameters gives further insight into the role of each ligand present in the Ru catalysts. This is the first report of a kinetic analysis of homogenous complexes’ catalysis including an analysis of their deactivation.
      PubDate: 2017-06-23
      DOI: 10.3390/catal7070193
      Issue No: Vol. 7, No. 7 (2017)
       
  • Catalysts, Vol. 7, Pages 194: Hydrothermal Carbonation Carbon-Coated CdS
           Nanocomposite with Enhanced Photocatalytic Activity and Stability

    • Authors: Yuanliang Ma, Zhongkun Zhao, Zhurui Shen, Qiang Cai, Huiming Ji, Leichao Meng
      First page: 194
      Abstract: Herein, a novel CdS nanocomposite is fabricated by a facile one-pot hydrothermal method assisted by glucose and polyvinylpyrrolidone (PVP). The as-prepared CdS is coated with a thin layer, which is determined to be hydrothermal carbonation carbon (HTCC) mainly containing semiconductive polyfuran. The as-prepared HTCC-coated CdS shows superior photocatalytic activity for the degradation of Rhodamine B (RhB) under visible light irradiation (λ ≥ 420 nm). The optimum sample (glucose content of 0.1 g) shows a degradation rate four-times that of pure CdS reference. Moreover, it also shows an improved stability, and the activity can be maintained at 96.2% after three cycles of recycling. The enhanced photocatalytic activity and stability of nanocomposite can mainly be attributed to: (i) The addition of PVP in the reaction solution can significantly increase the specific surface area of CdS and thus offer more active sites; (ii) The HTCC in the nanocomposite can expand the range of light absorption; (iii) The HTCC layer can form a heterojunction with CdS and improve the charge separation and transfer.
      PubDate: 2017-06-24
      DOI: 10.3390/catal7070194
      Issue No: Vol. 7, No. 7 (2017)
       
  • Catalysts, Vol. 7, Pages 195: Intramolecular Transfer of Pd Catalyst on
           Carbon–Carbon Triple Bond and Nitrogen–Nitrogen Double Bond in
           Suzuki–Miyaura Coupling Reaction

    • Authors: Takeru Kamigawara, Hajime Sugita, Koichiro Mikami, Yoshihiro Ohta, Tsutomu Yokozawa
      First page: 195
      Abstract: Intramolecular transfer of t-Bu3P-ligated Pd catalyst on a carbon–carbon triple bond (C≡C) and nitrogen–nitrogen double bond (N=N) was investigated and compared with the case of a carbon–carbon double bond (C=C), which is resistant to intramolecular transfer of the Pd catalyst. Suzuki–Miyaura coupling reaction of equimolar 4,4’-dibromotolan (1a) or 4,4’-dibromoazobenzene (1b) with 3-isobutoxyphenylboronic acid (2) was carried out in the presence of t-Bu3P-ligated Pd precatalyst 3 and KOH/18-crown-6 as a base at room temperature. In both cases, the diphenyl-substituted product was selectively obtained, indicating that the Pd catalyst walked from one benzene ring to the other through the C≡C or N=N bond after the first substitution with 2. Taking advantage of this finding, we conducted unstoichiometric Suzuki–Miyaura polycondensation of 1.3 equiv. of 1 and 1.0 equiv. of phenylenediboronic acid (ester) 6 in the presence of 3 and CsF/18-crown-6 as a base, obtaining high-molecular-weight conjugated polymer with a boronic acid (ester) moiety at both ends, contrary to the Flory principle.
      PubDate: 2017-06-23
      DOI: 10.3390/catal7070195
      Issue No: Vol. 7, No. 7 (2017)
       
  • Catalysts, Vol. 7, Pages 196: Selective Hydrogenolysis of Glycerol and
           Crude Glycerol (a By-Product or Waste Stream from the Biodiesel Industry)
           to 1,2-Propanediol over B2O3 Promoted Cu/Al2O3 Catalysts

    • Authors: Malaya Nanda, Zhongshun Yuan, Hengfu Shui, Chunbao Xu
      First page: 196
      Abstract: The performance of boron oxide (B2O3)-promoted Cu/Al2O3 catalyst in the selective hydrogenolysis of glycerol and crude glycerol (a by-product or waste stream from the biodiesel industry) to produce 1,2-propanediol (1,2-PDO) was investigated. The catalysts were characterized using N2-adsorption-desorption isotherm, Inductively coupled plasma atomic emission spectroscopy (ICP-AES), X-ray diffraction (XRD), ammonia temperature programmed desorption (NH3-TPD), thermogravimetric analysis (TGA), temperature programmed reduction (TPR), and transmission electron microscopy (TEM). Incorporation of B2O3 to Cu/Al2O3 was found to enhance the catalytic activity. At the optimum condition (250 °C, 6 MPa H2 pressure, 0.1 h−1 WHSV (weight hourly space velocity), and 5Cu-B/Al2O3 catalyst), 10 wt% aqueous solution of glycerol was converted into 1,2-PDO at 98 ± 2% glycerol conversion and 98 ± 2% selectivity. The effects of temperature, pressure, boron addition amount, and liquid hourly space velocity were studied. Different grades of glycerol (pharmaceutical, technical, or crude glycerol) were used in the process to investigate the stability and resistance to deactivation of the selected 5Cu-B/Al2O3 catalyst.
      PubDate: 2017-06-25
      DOI: 10.3390/catal7070196
      Issue No: Vol. 7, No. 7 (2017)
       
  • Catalysts, Vol. 7, Pages 197: The Effects of CeO2 Nanorods and CeO2
           Nanoflakes on Ni–S Alloys in Hydrogen Evolution Reactions in Alkaline
           Solutions

    • Authors: Meiqin Zhao, Yao Li, Haifeng Dong, Lixin Wang, Zhouhao Chen, Yazhou Wang, Zhiping Li, Meirong Xia, Guangjie Shao
      First page: 197
      Abstract: Composite coatings synthesized by different morphologies of CeO2 in supergravity devices are highly active in hydrogen evolution reactions (HERs). By adding CeO2 nanoflakes (CeO2 Nf) or CeO2 nanorods (CeO2 Nr), the change in the microstructures of composites becomes quite distinct. Moreover, most Ni–S alloys are attached on the surface of CeO2 and roughen it compare with pure CeO2. In order to make the expression more concise, this paper uses M instead of Ni–S. At a current density of 10 mA/cm2, overpotentials of Ni–S/CeO2 Nr (M–CeO2 Nr) and Ni–S/CeO2 Nf (M–CeO2 Nf) are 200 mV and 180 mV respectively, which is lower than that of Ni–S (M-0) coating (240 mV). The exchange current density (j0) values of M–CeO2 Nf and M–CeO2 Nr are 7.48 mA/cm2 and 7.40 mA/cm2, respectively, which are higher than that of M-0 (6.39 mA/cm2). Meanwhile, double-layer capacitances (Cdl) values of M–CeO2 Nf (6.4 mF/cm2) and M–CeO2 Nr (6 mF/cm2) are 21.3 times and 20 times of M-0 (0.3 mF/cm2), respectively
      PubDate: 2017-06-27
      DOI: 10.3390/catal7070197
      Issue No: Vol. 7, No. 7 (2017)
       
  • Catalysts, Vol. 7, Pages 198: Ordered PtSn/C Electrocatalyst: A High
           Performance Material for the Borohydride Electrooxidation Reaction

    • Authors: Francielle Bortoloti, Antonio Angelo
      First page: 198
      Abstract: This work used a rotating disc electrode and quasi-steady state polarization curves to investigate the sodium borohydride electrooxidation of ordered intermetallic PtSn/C in alkaline solution. Under similar experimental conditions, PtSn/C proved to be a better electrocatalyst than Pt in an overall process that involved eight electrons. Assays performed in the presence of thiourea and S2− species evidenced that a chemical hydrolysis step took place, followed by electrochemical oxidation of the generated H2. The results presented herein suggest that PtSn/C constitutes a promising electrode material for application in alkaline borohydride fuel cell.
      PubDate: 2017-06-29
      DOI: 10.3390/catal7070198
      Issue No: Vol. 7, No. 7 (2017)
       
  • Catalysts, Vol. 7, Pages 199: A Review on Selective Catalytic Reduction of
           NOx by NH3 over Mn–Based Catalysts at Low Temperatures: Catalysts,
           Mechanisms, Kinetics and DFT Calculations

    • Authors: Fengyu Gao, Xiaolong Tang, Honghong Yi, Shunzheng Zhao, Chenlu Li, Jingying Li, Yiran Shi, Xiaomi Meng
      First page: 199
      Abstract: It is a major challenge to develop the low–temperature catalysts (LTC, <250 °C) with excellent efficiency and stability for selective catalytic reduction (SCR) of NOx by NH3 from stationary sources. Mn-based LTC have been widely investigated due to its various valence states and excellent redox performance, while the poisoning by H2O or/and SO2 is one of the severe weaknesses. This paper reviews the latest research progress on Mn-based catalysts that are expected to break through the resistance, such as modified MnOx–CeO2, multi-metal oxides with special crystal or/and shape structures, modified TiO2 supporter, and novel carbon supporter (ACF, CNTs, GE), etc. The SCR mechanisms and promoting effects of redox cycle are described in detail. The reaction kinetics will be a benefit for the quantitative study of Eley–Rideal (ER) and Langmuir–Hinshelwood (LH) mechanisms. This paper also introduces the applications of quantum-chemical calculation using density functional theory to analyze the physic-chemical properties, explicates the reaction and poisoning mechanisms, and directs the design of functional catalysts on molecule levels. The intensive study of H2O/SO2 inhibition effects is by means of the combination analysis of in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and density functional theory (DFT), and the amplification of tolerance mechanisms will be helpful to design an excellent SCR catalyst.
      PubDate: 2017-06-29
      DOI: 10.3390/catal7070199
      Issue No: Vol. 7, No. 7 (2017)
       
  • Catalysts, Vol. 7, Pages 200: Activated Carbon Supported Mo-Ti-N Binary
           Transition Metal Nitride as Catalyst for Acetylene Hydrochlorination

    • Authors: Hui Dai, Mingyuan Zhu, Haiyang Zhang, Feng Yu, Chao Wang, Bin Dai
      First page: 200
      Abstract: Recently, many scientists have focused on the development of green industrial technology. However, the process of synthesizing vinyl chloride faces the problem of Hg pollution. Via a novel approach, we used two elements Mo and Ti to prepare an inexpensive and green binary transition metal nitride (BTMN) as the active ingredient in a catalyst with nano-sized particles and an excellent degree of activation, which was supported on activated carbon. When the Mo/Ti mole ratio was 3:1, the conversion of acetylene reached 89% and the selectivity exceeded 98.5%. The doping of Ti in Mo-based catalysts reduced the capacity of adsorption for acetylene and also increased the adsorption of hydrogen chloride. Most importantly, the performance of the BTMN excelled those of the individual transition metal nitrides, due to the synergistic activity between Mo and Ti. This will expand the new epoch of the employment of transition metal nitrides as catalysts in the hydrochlorination of acetylene reaction.
      PubDate: 2017-06-30
      DOI: 10.3390/catal7070200
      Issue No: Vol. 7, No. 7 (2017)
       
  • Catalysts, Vol. 7, Pages 201: Highly Effective Dual Transition Metal
           Macrocycle Based Electrocatalyst with Macro-/Mesoporous Structures for
           Oxygen Reduction Reaction

    • Authors: Xinxin Jin, Yan Xie, Jiahui Huang
      First page: 201
      Abstract: Metal macrocycle based non-noble metal electrocatalysts (NNMEs) with highly efficient oxygen reduction reaction (ORR) activity, good stability, and excellent resistance to the methanol cross-over effect have been regarded as one of the most important alternatives for Pt or Pt based alloys, which are widely used in fuel cells. However, the expensive price of most metal macrocycles hinder further investigation of such a family of NNMEs in large production for practical applications. Here, we introduce a simple strategy to synthesize metal macrocycle based porous carbon (MMPC) material with low cost and easy production of metal macrocycles (hemin (Hm) and vitamin B12 (VB12)) as raw materials by using a hard template of MgO. The pyrolysis of MMPC under the optimal temperature at 900 °C shows comparative ORR performance relative to commercial Pt/C, which could be attributed to the large surface area, macro-/mesoporous structure, the carbon layer encapsulating transition metal based oxides, as well as N-doped carbon species. In addition, MMPC (900) displays a better electrochemical property than 20 wt % Pt/C in terms of durability and tolerance to methanol in O2-saturated 0.1 M KOH media.
      PubDate: 2017-06-30
      DOI: 10.3390/catal7070201
      Issue No: Vol. 7, No. 7 (2017)
       
  • Catalysts, Vol. 7, Pages 202: High Active Zn/Mg-Modified Ni–P/Al2O3
           Catalysts Derived from ZnMgNiAl Layered Double Hydroxides for
           Hydrodesulfurization of Dibenzothiophene

    • Authors: Feng Li, Jinrong Liang, Wenxi Zhu, Hua Song, Keliang Wang, Cuiqin Li
      First page: 202
      Abstract: A series of ZnMgNiAl layered double hydroxides (LDHs) containing 20 wt.% Ni and different Zn/Mg molar ratios were prepared by a coprecipitation method, and then were introduced with H2PO4− via a microwave-hydrothermal method. With the resulting mixtures as the precursors, Zn/Mg-modified ZnMgNi–P/Al2O3 catalysts were prepared. The Zn/Mg molar ratio affected the formation of Ni2P and Ni12P5 in nickel phosphides. The ZnMgNi–P/Al2O3 catalyst with a Zn/Mg molar ratio of 3:1 exhibits the best dibenzothiophene hydrodesulfurization (HDS) activity. Compared with the Ni–P/Al2O3 catalyst prepared from the impregnation method, the ZnMgNi–P/Al2O3 catalyst shows a higher HDS activity (81.6% vs. 54.3%) and promotes the direct desulfurization of dibenzothiophene.
      PubDate: 2017-07-04
      DOI: 10.3390/catal7070202
      Issue No: Vol. 7, No. 7 (2017)
       
  • Catalysts, Vol. 7, Pages 203: Rapid Jatropha-Castor Biodiesel Production
           with Microwave Heating and a Heterogeneous Base Catalyst
           Nano-Ca(OH)2/Fe3O4

    • Authors: Ken-Lin Chang, Yuan-Chung Lin, Syu-Ruei Jhang, Way Lee Cheng, Shang-Cyuan Chen, Sung-Yuan Mao
      First page: 203
      Abstract: In this study, a nano-Ca(OH)2/Fe3O4 catalyst was used to produce biodiesel from a 1:1 mixed jatropha-castor oil. By loading Ca(OH)2 onto Fe3O4 nanoparticles, it increased the specific surface area by almost 40%, which improved the catalytic activity as it provided a larger area for the reactants to interact. The main purpose of mixing jatropha oil with castor oil was to lower the viscosity of the castor oil. The transesterification reaction was carried out at elevated temperature, using a microwave heating system. Moreover, it was shown that the preferred reaction conditions are using high temperature and short reaction duration. The optimized yield of methyl ester was 95%, achieved by using a catalyst with a Ca:Fe ratio of 7:1, temperature of 65 °C, methanol/oil ratio of 12:1, and reaction time of 35 min. The catalyst was shown to be reusable, easily recyclable, and its activity was very stable. Only 2% of the catalyst was lost, and the yield was 3% lower after ten successive applications. The solid, magnetic base catalyst could be easily separated from the reaction products, unlike homogeneous catalysts.
      PubDate: 2017-07-04
      DOI: 10.3390/catal7070203
      Issue No: Vol. 7, No. 7 (2017)
       
  • Catalysts, Vol. 7, Pages 204: Acidity-Reactivity Relationships in
           Catalytic Esterification over Ammonium Sulfate-Derived Sulfated Zirconia

    • Authors: Abdallah Rabee, Gamal Mekhemer, Amin Osatiashtiani, Mark Isaacs, Adam Lee, Karen Wilson, Mohamed Zaki
      First page: 204
      Abstract: New insight was gained into the acidity-reactivity relationships of sulfated zirconia (SZ) catalysts prepared via (NH4)2SO4 impregnation of Zr(OH)4 for propanoic acid esterification with methanol. A family of systematically related SZs was characterized by bulk and surface analyses including XRD, XPS, TGA-MS, N2 porosimetry, temperature-programmed propylamine decomposition, and FTIR of adsorbed pyridine, as well as methylbutynol (MBOH) as a reactive probe molecule. Increasing surface sulfation induces a transition from amphoteric character for the parent zirconia and low S loadings <1.7 wt %, evidenced by MBOH conversion to 3-hydroxy-3-methyl-2-butanone, methylbutyne and acetone, with higher S loadings resulting in strong Brønsted-Lewis acid pairs upon completion of the sulfate monolayer, which favored MBOH conversion to prenal. Catalytic activity for propanoic acid esterification directly correlated with acid strength determined from propylamine decomposition, coincident with the formation of Brønsted-Lewis acid pairs identified by MBOH reactive titration. Monodispersed bisulfate species are likely responsible for superacidity at intermediate sulfur loadings.
      PubDate: 2017-07-05
      DOI: 10.3390/catal7070204
      Issue No: Vol. 7, No. 7 (2017)
       
  • Catalysts, Vol. 7, Pages 205: DeNOx Abatement Modelling over Sonically
           Prepared Copper USY and ZSM5 Structured Catalysts

    • Authors: Przemysław J. Jodłowski, Łukasz Kuterasiński, Roman J. Jędrzejczyk, Damian Chlebda, Anna Gancarczyk, Sylwia Basąg, Lucjan Chmielarz
      First page: 205
      Abstract: Metallic supports play an important role as structured reactor internals. Due to their specific properties including enhanced heat and mass transport, high mechanical resistivity and elimination of local hot-spots, they are commonly used in gas exhaust abatement from stationary and automotive industries. In this study, the performance of three structured supports with deposited Cu/USY (Ultrastabilised Y—zeolite) for deNOx abatement were modelled. Based on kinetic and flow resistance experimental results, the one-dimensional (1D) model of structured reactor was developed. The performance of the structured reactors was compared by the length of the reactor necessary to achieve an arbitrary 90% NOx conversion. The performed simulations showed that the sonochemically prepared copper USY and ZSM-5 zeolites deposited on metallic supports may be successfully used as catalysts for deNOx process.
      PubDate: 2017-07-06
      DOI: 10.3390/catal7070205
      Issue No: Vol. 7, No. 7 (2017)
       
  • Catalysts, Vol. 7, Pages 206: Cerium Coordination Polymer Based Composite
           Mimicking Peroxidase for Detection of Nitroaniline

    • Authors: Xi Wang, Kunkun Zheng, Peijun Ji
      First page: 206
      Abstract: Cerium coordination polymer (CeCP) was synthesized with 1,3,5-benzenetricarboxylic acid as the ligand. By using the carboxyl groups on the surface of CeCP as the anchors, platinum nanoparticles were formed on CeCP forming the composite CeCP@Pt. The composite was characterized by measuring TEM images, and EDS and XPS spectra. CeCP@Pt was used to catalyze the oxidation of 3,3,5,5-tetramethylbenzidine in the presence of H2O2. The activity assay demonstrated that CeCP@Pt exhibited an activity similar to that of horseradish peroxidase, but with a much higher activity. CeCP@Pt was utilized to detect nitroaniline, being able to detect trace amount of nitroaniline (>3.125 × 10−4 mg/mL).
      PubDate: 2017-07-07
      DOI: 10.3390/catal7070206
      Issue No: Vol. 7, No. 7 (2017)
       
  • Catalysts, Vol. 7, Pages 207: Bimetallic Nanoparticles in Alternative
           Solvents for Catalytic Purposes

    • Authors: Trung Dang-Bao, Daniel Pla, Isabelle Favier, Montserrat Gómez
      First page: 207
      Abstract: Bimetallic nanoparticles represent attractive catalytic systems thanks to the synergy between both partners at the atomic level, mainly induced by electronic effects which in turn are associated with the corresponding structures (alloy, core-shell, hetero-dimer). This type of engineered material can trigger changes in the kinetics of catalyzed processes by variations on the electrophilicity/nucleophilicity of the metal centers involved and also promote cooperative effects to foster organic transformations, including multi-component and multi-step processes. Solvents become a crucial factor in the conception of catalytic processes, not only due to their environmental impact, but also because they can preserve the bimetallic structure during the catalytic reaction and therefore increase the catalyst life-time. In this frame, the present review focuses on the recent works described in the literature concerning the synthesis of bimetallic nanoparticles in non-conventional solvents, i.e., other than common volatile compounds, for catalytic applications.
      PubDate: 2017-07-07
      DOI: 10.3390/catal7070207
      Issue No: Vol. 7, No. 7 (2017)
       
  • Catalysts, Vol. 7, Pages 208: Newly Designed Ternary Metallic PtPdBi
           Hollow Catalyst with High Performance for Methanol and Ethanol Oxidation

    • Authors: Zhiping Xiong, Shumin Li, Hui Xu, Ke Zhang, Bo Yan, Yukou Du
      First page: 208
      Abstract: This paper reported the fabrication of ternary metallic PtPdBi hollow nanocatalyst through a facile, one-pot, wet-chemical method by adopting sodium borohydride and polyvinylpyrrolidone as reducing agent and surfactant directing agent, respectively. The hollow structure offers novel morphology and large surface areas, which are conducive to enhancing the electrocatalytic activity. The electrocatalytic properties of hollow PtPdBi nanocatalyst were investigated systematically in alkaline media through cyclic voltammetry and the as-prepared PtPdBi nanocatalyst displays greatly enhanced electrocatalytic activities towards methanol and ethanol oxidation. The calculated mass activities of PtPdBi electrocatalyst are 2.133 A mgPtPd−1 for methanol oxidation reaction and 5.256 A mgPtPd−1 for ethanol oxidation reaction, which are much better than that of commercial Pt/C and commercial Pd/C. The as-prepared hollow nanocatalyst may be a potential promising electrocatalyst in fuel cells and also may be extended to the applications of other desirable functions.
      Citation: Catalysts
      PubDate: 2017-07-10
      DOI: 10.3390/catal7070208
      Issue No: Vol. 7, No. 7 (2017)
       
  • Catalysts, Vol. 7, Pages 209: Low-Temperature Synthesis of
           Anatase/Rutile/Brookite TiO2 Nanoparticles on a Polymer Membrane for
           Photocatalysis

    • Authors: Kristina Fischer, Alina Gawel, David Rosen, Maria Krause, Amira Abdul Latif, Jan Griebel, Andrea Prager, Agnes Schulze
      First page: 209
      Abstract: Removing pollutants from water by using the photocatalyst TiO2 is a highly-promising method. A large amount of work has been done to increase the activity of TiO2, whereas the main two findings are increasing the surface area and applying mixed phase modifications (anatase, brookite, and rutile). Here, we present a method to directly synthesize non-agglomerated TiO2 nanoparticles with different crystal phase ratios via low temperature dissolution-precipitation (LTDRP) on a porous microfiltration membrane (polyethersulfone). The amount of hydrochloric acid and the temperature was varied between 0.1–1 M and 25–130 °C, respectively, while the concentration of titanium precursor (titanium(IV) isopropoxide) was kept unchanged. The TiO2 nanoparticles and the membrane were thoroughly characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), measuring the water contact angle and permeation flux, and examining the degradation of methylene blue. The mixed phase anatase/brookite with a main component being anatase exhibited the highest photocatalytic activity in removing methylene blue. Higher synthesis temperature induces enhanced crystallinity and, subsequently, the degradation rate of methylene blue was improved. Additionally, the photocatalytic activity remains high and unchanged for up to nine repeated cycles, i.e., full recovery of the photocatalytic properties is sustained.
      Citation: Catalysts
      PubDate: 2017-07-10
      DOI: 10.3390/catal7070209
      Issue No: Vol. 7, No. 7 (2017)
       
  • Catalysts, Vol. 7, Pages 210: Solventless Coupling of Epoxides and CO2 in
           Compressed Medium Catalysed by Fluorinated Metalloporphyrins

    • Authors: Rui Carrilho, Lucas Dias, Raquel Rivas, Mariette Pereira, Carmen Claver, Anna Masdeu-Bultó
      First page: 210
      Abstract: Metal complexes of meso-arylporphyrins (Cr(III), Fe(III), and Zn(II)) were evaluated in the coupling reaction of cyclohexene oxide (CHO) with CO2 in compressed medium, where the Cr complexes were demonstrated to be the most active systems, leading predominantly to copolymerisation products. It is noteworthy that no addition of solvent was required. To improve the catalytic activity, and to simultaneously increase the solubility in compressed CO2, a new fluorinated catalyst, tetrakis(4-trifluoromethylphenyl)porphyrinatochromium(III) chloride (CrCl-pCF3TPP), was applied to this reaction. The alternating copolymerisation of CHO with CO2, using the Cr(III) fluorinated porphyrin catalyst, required the use of a co-catalyst, bis(triphenylphosphine)iminium chloride (PPNCl), with the best yields of copolymers being obtained at 80 °C, and CO2 pressures in the range of 50–110 bar, over a period of 24 h, with a low catalyst/substrate molar ratio (0.07%). The polycarbonate’s structure was analysed by 1H NMR, 13C NMR, and MALDI-TOF spectroscopy, which demonstrated high carbonate incorporations (98–99%). Gel permeation chromatography revealed number-average molecular weights (Mn) in the range of 4800–12,800 and narrow molecular weight distributions (Mw/Mn ≤ 1.63).
      Citation: Catalysts
      PubDate: 2017-07-14
      DOI: 10.3390/catal7070210
      Issue No: Vol. 7, No. 7 (2017)
       
  • Catalysts, Vol. 7, Pages 211: Arenesulfonic Acid-Functionalized Bentonite
           as Catalyst in Glycerol Esterification with Acetic Acid

    • Authors: Maryam Tangestanifard, Hassan Ghaziaskar
      First page: 211
      Abstract: The present study is focused on the synthesis of arenesulfonic acid-functionalized bentonite as a catalyst to produce monoacetin, diacetin, and triacetin from glycerol and acetic acid using toluene as solvent and a water removing agent. The best conditions for the present reaction with acetic acid were an acetic acid:glycerol:toluene molar ratio of 7:1:1.4, 100 °C, and 0.074 wt % of catalyst (based on the total weight of glycerol). Under the reaction conditions, 96% glycerol conversion was achieved within 0.5 h from the start of the reaction. The maximum selectivity of 66% and 74% were achieved for diacetin and triacetin after 0.5 and 3 h of reaction, respectively, without formation of any byproduct. The arenesulfonic acid-functionalized bentonite was characterized by X-ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy, N2 adsorption/desorption experiments (Brunauer, Emmett and Teller, BET, method), field emission scanning electron microscopy, and the surface acidity was determined by back titration. Without significant treatment, the catalyst was reusable for 5 consecutive runs.
      Citation: Catalysts
      PubDate: 2017-07-14
      DOI: 10.3390/catal7070211
      Issue No: Vol. 7, No. 7 (2017)
       
  • Catalysts, Vol. 7, Pages 212: In Silico Studies of Small Molecule
           Interactions with Enzymes Reveal Aspects of Catalytic Function

    • Authors: Rajni Verma, Katie Mitchell-Koch
      First page: 212
      Abstract: Small molecules, such as solvent, substrate, and cofactor molecules, are key players in enzyme catalysis. Computational methods are powerful tools for exploring the dynamics and thermodynamics of these small molecules as they participate in or contribute to enzymatic processes. In-depth knowledge of how small molecule interactions and dynamics influence protein conformational dynamics and function is critical for progress in the field of enzyme catalysis. Although numerous computational studies have focused on enzyme–substrate complexes to gain insight into catalytic mechanisms, transition states and reaction rates, the dynamics of solvents, substrates, and cofactors are generally less well studied. Also, solvent dynamics within the biomolecular solvation layer play an important part in enzyme catalysis, but a full understanding of its role is hampered by its complexity. Moreover, passive substrate transport has been identified in certain enzymes, and the underlying principles of molecular recognition are an area of active investigation. Enzymes are highly dynamic entities that undergo different conformational changes, which range from side chain rearrangement of a residue to larger-scale conformational dynamics involving domains. These events may happen nearby or far away from the catalytic site, and may occur on different time scales, yet many are related to biological and catalytic function. Computational studies, primarily molecular dynamics (MD) simulations, provide atomistic-level insight and site-specific information on small molecule interactions, and their role in conformational pre-reorganization and dynamics in enzyme catalysis. The review is focused on MD simulation studies of small molecule interactions and dynamics to characterize and comprehend protein dynamics and function in catalyzed reactions. Experimental and theoretical methods available to complement and expand insight from MD simulations are discussed briefly.
      Citation: Catalysts
      PubDate: 2017-07-14
      DOI: 10.3390/catal7070212
      Issue No: Vol. 7, No. 7 (2017)
       
  • Catalysts, Vol. 7, Pages 213: Pure and Fe-Doped Mesoporous Titania
           Catalyse the Oxidation of Acid Orange 7 by H2O2 under Different
           Illumination Conditions: Fe Doping Improves Photocatalytic Activity under
           Simulated Solar Light

    • Authors: Francesca Freyria, Matteo Compagnoni, Nicoletta Ditaranto, Ilenia Rossetti, Marco Piumetti, Gianguido Ramis, Barbara Bonelli
      First page: 213
      Abstract: A sample of mesoporous TiO2 (MT, specific surface area = 150 m2·g−1) and two samples of MT containing 2.5 wt.% Fe were prepared by either direct synthesis doping (Fe2.5-MTd) or impregnation (Fe2.5-MTi). Commercial TiO2 (Degussa P25, specific surface area = 56 m2 g−1) was used both as a benchmark and as a support for impregnation with either 0.8 or 2.5 wt.% Fe (Fe0.80-IT and Fe2.5-IT). The powders were characterized by X-ray diffraction, N2 isotherms at −196 °C, Energy Dispersive X-ray (EDX) Spectroscopy, X-ray Photoelectron Spectroscopy (XPS), Diffuse Reflectance (DR) ultra-violet (UV)-Vis and Mössbauer spectroscopies. Degradation of Acid Orange 7 (AO7) by H2O2 was the test reaction: effects of dark-conditions versus both UV and simulated solar light irradiation were considered. In dark conditions, AO7 conversion was higher with MT than with Degussa P25, whereas Fe-containing samples were active in a (slow) Fenton-like reaction. Under UV light, MT was as active as Degussa P25, and Fe doping enhanced the photocatalytic activity of Fe2.5-MTd; Fe-impregnated samples were also active, likely due to the occurrence of a photo-Fenton process. Interestingly, the Fe2.5-MTd sample showed the best performance under solar light, confirming the positive effect of Fe doping by direct synthesis with respect to impregnation.
      Citation: Catalysts
      PubDate: 2017-07-18
      DOI: 10.3390/catal7070213
      Issue No: Vol. 7, No. 7 (2017)
       
  • Catalysts, Vol. 7, Pages 214: Sulfur-Doped TiO2: Structure and Surface
           Properties

    • Authors: Sara Cravanzola, Federico Cesano, Fulvio Gaziano, Domenica Scarano
      First page: 214
      Abstract: A comprehensive study on the sulfur doping of TiO2, by means of H2S treatment at 673 K, has been performed in order to highlight the role of sulfur in affecting the properties of the system, as compared to the native TiO2. The focus of this study is to find a relationship among the surface, structure, and morphology properties, by means of a detailed chemical and physical characterization of the samples. In particular, transmission electron microscopy images provide a simple tool to have a direct and immediate evidence of the effects of H2S action on the TiO2 particles structure and surface defects. Furthermore, from spectroscopy analyses, the peculiar surface, optical properties, and methylene blue photodegradation test of S-doped TiO2 samples, as compared to pure TiO2, have been investigated and explained by the effects caused by the exchange of S species with O species and by the surface defects induced by the strong H2S treatment.
      Citation: Catalysts
      PubDate: 2017-07-18
      DOI: 10.3390/catal7070214
      Issue No: Vol. 7, No. 7 (2017)
       
  • Catalysts, Vol. 7, Pages 215: Mo(VI) Complexes Immobilized on SBA-15 as an
           Efficient Catalyst for 1-Octene Epoxidation

    • Authors: Jovita Moreno, Jose Iglesias, Juan Melero
      First page: 215
      Abstract: SBA-15 materials were functionalized through a post-synthetic methodology with molybdenum-Schiff bases to provide catalytic activity in epoxidation reactions. Thus, glycidoxypropyl functionalities were first attached to the surface of the mesostructured silica, followed by the reaction of the immobilized oxirane groups with 2-amino propyl pyridine. This reaction allowed the obtaining of (hydroxypropyl)-2-aminomethyl pyridine ligands, directly tethered to the surface of the mesoporous silica-based SBA-15, which resulted in excellent chelating ligands to immobilize dioxo molydenum species by a reaction with MoO2(acac)2. This investigation comprises a thorough characterization of the process for building the immobilized molybdenum-Schiff base complexes, as well as the use of the obtained materials in 1-octene oxidation in the presence of organic hydroperoxides. These materials displayed high intrinsic catalytic activity in the epoxidation of 1-octene with organic hydroperoxides under a wide variety of conditions, although both the reaction solvent as well as the nature of the organic hydroperoxide, exerted a dramatic influence on the catalytic activity of these heterogeneous oxidation catalysts. Thus, whereas nonpolar solvents provided good epoxide yields with high efficiency in the use of the oxidant, polar solvents depressed the catalytic activity of the supported Mo-Schiff bases. These results have been ascribed to the competition with the solvent, when polar, for binding to the metal sites, thus avoiding the formation of the hydroperoxo-metal cycle and the epoxidation of the olefin. The catalysts presented here show good reusability with low catalytic activity decay after the first reuse.
      Citation: Catalysts
      PubDate: 2017-07-18
      DOI: 10.3390/catal7070215
      Issue No: Vol. 7, No. 7 (2017)
       
  • Catalysts, Vol. 7, Pages 216: Highly ordered Nanomaterial Functionalized
           Copper Schiff Base Framework: Synthesis, Characterization, and Hydrogen
           Peroxide Decomposition Performance

    • Authors: Fatemeh Rajabi, María Pinilla-de Dios, Rafael Luque
      First page: 216
      Abstract: An immobilized copper Schiff base tridentate complex was prepared in three steps from SBA-15 supports. The immobilized copper nanocatalyst (heterogeneous catalyst) was characterized by Fourier transform infrared spectroscopy (FT-IR), cross polarization magic angle spinning (CP-MAS), 13-carbon nuclear magnetic resonance (13C-NMR), atomic absorption spectroscopy (AAS), thermogravimetric analysis (TGA), and N2-physisorption. Moreover, morphological and structural features of the immobilized nanocatalyst were analyzed using transmission electron microscopy (TEM) and X-ray powder diffraction spectrometry (PXRD). After characterizing the nanocatalyst, the catalytic activity was determined in hydrogen peroxide (H2O2) decomposition. The high decomposition yield of H2O2 was obtained for low-loaded copper content materials at pH 7 and at room temperature. Furthermore, the nanocatalyst exhibited high activity and stability under the investigated conditions, and could be recovered and reused for at least five consecutive times without any significant loss in activity. No copper leaching was detected during the reaction by AAS measurements.
      Citation: Catalysts
      PubDate: 2017-07-19
      DOI: 10.3390/catal7070216
      Issue No: Vol. 7, No. 7 (2017)
       
  • Catalysts, Vol. 7, Pages 217: Co-Immobilization of Superoxide Dismutase
           with Catalase on Soft Microparticles Formed by Self-Assembly of
           Amphiphilic Poly(Aspartic Acid)

    • Authors: Siyu Mao, Rong Li, Wenchen Wang, Wei Feng, Peijun Ji
      First page: 217
      Abstract: Through genetic engineering technology, catalase (CAT) and superoxide dismutase (SOD) have been separately fused to an elastin-like polypeptide (ELP). Thus, the enzymes can be purified through phase transition. Hexadecylamine-modified poly(aspartic acid) (HPASP) is able to self-assemble, forming soft microparticles. The HPASP microparticles were used to co-immobilize SOD-ELP and CAT-ELP through amidation reaction. Circular dichroism (CD) confirmed that the secondary structures of the co-immobilized enzymes have been preserved. Fluorescence spectra showed that the co-immobilized enzymes exhibited a higher stability than the free enzymes. Dismutation of superoxide by superoxide dismutase (SOD) generates hydrogen peroxide. By using the co-immobilized enzymes (SOD-ELP/CAT-ELP@HPASP), the generated hydrogen peroxide of SOD-ELP can be decomposed in situ by CAT-ELP. Activity assay results demonstrated that the superoxide anion (•O2−) scavenging ability is 63.15 ± 0.75% for SOD-ELP/CAT-ELP@HPASP. The advantages of the approach of enzyme co-immobilization include the fact that the soft support HPASP itself is a polypeptide in nature, the stability of immobilized enzymes is improved, and a high activity has been achieved. Potentially SOD-ELP/CAT-ELP@HPASP can be applied in the cosmetic industry.
      Citation: Catalysts
      PubDate: 2017-07-19
      DOI: 10.3390/catal7070217
      Issue No: Vol. 7, No. 7 (2017)
       
  • Catalysts, Vol. 7, Pages 218: Catalytic Conversion of Carbohydrates to
           Furanic Derivatives in the Presence of Choline Chloride

    • Authors: François Jérôme, Karine De Oliveira Vigier
      First page: 218
      Abstract: The synthesis of furanic derivatives (5-hydroxymethylfurfural (HMF), furfural…) from carbohydrates is of high interest for a wide range of applications. These reactions are carried out in the presence of various solvents, and among them choline chloride can be used. It is a salt that can form a low melting mixture with a carbohydrate (fructose, glucose…) or a deep eutectic mixture with carboxylic acid. A review of the studies performed in the conversion of carbohydrates to furanic derivatives in the presence of choline chloride is presented here with the advantages and drawbacks of this solvent. Choline chloride can enhance the selectivity to HMF by stabilizing effect and allows the conversion of highly concentrated feed. However, the extraction of the products from these solvents still needs improvement.
      Citation: Catalysts
      PubDate: 2017-07-20
      DOI: 10.3390/catal7070218
      Issue No: Vol. 7, No. 7 (2017)
       
  • Catalysts, Vol. 7, Pages 219: Recyclable Fe3O4 Nanoparticles Catalysts for
           Aza-Michael Addition of Acryl Amides by Magnetic Field

    • Authors: Zhen-Xing Li, Dan Luo, Ming-Ming Li, Xiao-Fei Xing, Zheng-Zheng Ma, Hao Xu
      First page: 219
      Abstract: A nanostructure-based catalytic system has the advantages of both homogeneous and heterogeneous catalysis. It is of great significance to develop the sustainable and green process of homogeneous catalytic reaction. We report a novel, efficient and recyclable magnetic Fe3O4 nanoparticles-catalyzed aza-Michael addition reaction of acryl amides, and the magnetic nanoparticles catalysts can be recovered by external magnetic field. Both primary amine and secondary amine can react with various acryl amides providing a good output to target products successfully at room temperature. Further experiments reveal that the magnetic Fe3O4 nanoparticles-based catalyst shows excellent yields, which can be recycled 10 times, and, at the same time, it maintains a high catalytically activity. In this catalytic system, the tedious separation procedures are replaced by external magnetic field, which gives us a different direction for choosing a catalyst in a nanostructure-based catalytic system.
      Citation: Catalysts
      PubDate: 2017-07-20
      DOI: 10.3390/catal7070219
      Issue No: Vol. 7, No. 7 (2017)
       
  • Catalysts, Vol. 7, Pages 220: Electroreduction of CO2 into Ethanol over an
           Active Catalyst: Copper Supported on Titania

    • Authors: Jing Yuan, Li Liu, Rong-Rong Guo, Sheng Zeng, Huan Wang, Jia-Xing Lu
      First page: 220
      Abstract: A simple, inexpensive, and novel method was used to prepare electrocatalysts from Cu supported on titanium dioxide (Cu/TiO2). XRD, SEM, and TEM characterizations confirmed different loadings of Cu nanoparticles (NPs) on TiO2. Cyclic voltammetry tests indicated that Cu/TiO2 exhibited lower overpotential for CO2 reduction than that of Cu NPs. Moreover, 40 wt % Cu/TiO2 exhibited the highest faradaic efficiency for ethanol (FEethanol) of 27.4%, which is approximately 10-fold higher than that for Cu NPs (FEethanol = 2.7%). The 40 wt % Cu/TiO2 electrocatalyst exhibits a stable current density of 8.66 mA/cm2 over a 25 h stability test. The high efficiency towards CO2 electroreduction to ethanol may be attributed to the synergistic effect of Cu and TiO2 NPs. This work highlights the importance of compositional effect of NPs on their catalytic activities and provides a strategy for designing efficient catalysts for CO2 electroreduction in the future.
      Citation: Catalysts
      PubDate: 2017-07-20
      DOI: 10.3390/catal7070220
      Issue No: Vol. 7, No. 7 (2017)
       
  • Catalysts, Vol. 7, Pages 221: Conversion of Cellulose to Lactic Acid by
           Using ZrO2–Al2O3 Catalysts

    • Authors: Panya Wattanapaphawong, Osamu Sato, Koichi Sato, Naoki Mimura, Prasert Reubroycharoen, Aritomo Yamaguchi
      First page: 221
      Abstract: Lactic acid has a wide range of applications in many industries, both as an ingredient and as an intermediate. Here, we investigated the catalytic conversion of cellulose to lactic acid by using heterogeneous mixed-oxide catalysts containing ZrO2. Although pure ZrO2 has catalytic activity for the conversion of cellulose to lactic acid, the yield of lactic acid obtained is not satisfactory. In contrast, a series of ZrO2–Al2O3 catalysts containing various percentages of ZrO2 provided higher yields of lactic acid. The ZrO2–Al2O3 catalysts had more Lewis acid sites and far fewer base sites than ZrO2. This suggests that the Lewis acid sites on ZrO2–Al2O3 catalysts are more important than the base sites for the conversion of cellulose to lactic acid.
      Citation: Catalysts
      PubDate: 2017-07-21
      DOI: 10.3390/catal7070221
      Issue No: Vol. 7, No. 7 (2017)
       
  • Catalysts, Vol. 7, Pages 167: Synthesis, Structural Characterization and
           

    • Authors: Jiří Schulz, Filip Horký, Ivana Císařová, Petr Štěpnička
      First page: 167
      Abstract: Triethylammonium salts of phosphinoferrocene amidosulfonates with electron-rich dialkyphosphino substituents, R2PfcCONHCH2SO3(HNEt3) (4a–c), where fc = ferrocene-1,1′-diyl, and R = i-Pr (a), cyclohexyl (Cy; b), and t-butyl (c), were synthesized from the corresponding phosphinocarboxylic acids-borane adducts, R2PfcCO2H·BH3 (1a–c), via esters R2PfcCO2C6F5·BH3 (2a–c) and adducts R2PfcCONHCH2SO3(HNEt3)·BH3 (3a–c). Compound 4b was shown to react with [Pd(μ-Cl)(η-C3H5)]2 and AgClO4 to afford the zwitterionic complex [Pd(η3-C3H5)(Cy2PfcCONHCH2SO3-κ2O,P)] (5b), in which the amidosulfonate ligand coordinates as a chelating donor making use of its phosphine moiety and amide oxygen. The structures of 3b·CH2Cl2, 4b and 5b·CH2Cl2 were determined by single-crystal X-ray diffraction analysis. Compounds 4a–c and their known diphenylphosphino analogue, Ph2PfcCONHCH2SO3(HNEt3) (4d), were studied as supporting ligands in Pd-catalyzed cyanation of aryl bromides with K4[Fe(CN)6] and in Suzuki–Miyaura biaryl cross-coupling performed in aqueous reaction media under mild reaction conditions. In the former reaction, the best results were achieved with a catalyst generated from [PdCl2(cod)] (cod = η2:η2-cycloocta-1,5-diene) and 2 equiv. of the least electron-rich ligand 4d in dioxane–water as a solvent. In contrast, the biaryl coupling was advantageously performed with a catalyst resulting from palladium(II) acetate and ligand 4a (1 equiv.) in the same solvent.
      PubDate: 2017-05-24
      DOI: 10.3390/catal7060167
      Issue No: Vol. 7, No. 6 (2017)
       
  • Catalysts, Vol. 7, Pages 168: The Power of Non-Hydrolytic Sol-Gel
           Chemistry: A Review

    • Authors: Ales Styskalik, David Skoda, Craig Barnes, Jiri Pinkas
      First page: 168
      Abstract: This review is devoted to non-hydrolytic sol-gel chemistry. During the last 25 years, non-hydrolytic sol-gel (NHSG) techniques were found to be attractive and versatile methods for the preparation of oxide materials. Compared to conventional hydrolytic approaches, the NHSG route allows reaction control at the atomic scale resulting in homogeneous and well defined products. Due to these features and the ability to design specific materials, the products of NHSG reactions have been used in many fields of application. The aim of this review is to present an overview of NHSG research in recent years with an emphasis on the syntheses of mixed oxides, silicates and phosphates. The first part of the review highlights well known condensation reactions with some deeper insights into their mechanism and also presents novel condensation reactions established in NHSG chemistry in recent years. In the second section we discuss porosity control and novel compositions of selected materials. In the last part, the applications of NHSG derived materials as heterogeneous catalysts and supports, luminescent materials and electrode materials in Li-ion batteries are described.
      PubDate: 2017-05-25
      DOI: 10.3390/catal7060168
      Issue No: Vol. 7, No. 6 (2017)
       
  • Catalysts, Vol. 7, Pages 169: An Overview on Catalytic Hydrodeoxygenation
           of Pyrolysis Oil and Its Model Compounds

    • Authors: Zhan Si, Xinghua Zhang, Chenguang Wang, Longlong Ma, Renjie Dong
      First page: 169
      Abstract: Pyrolysis is considered the most promising way to convert biomass to fuels. Upgrading biomass pyrolysis oil is essential to produce high quality hydrocarbon fuels. Upgrading technologies have been developed for decades, and this review focuses on the hydrodeoxygenation (HDO). In order to declare the need for upgrading, properties of pyrolysis oil are firstly analyzed, and potential analysis methods including some novel methods are proposed. The high oxygen content of bio-oil leads to its undesirable properties, such as chemical instability and a strong tendency to re-polymerize. Acidity, low heating value, high viscosity and water content are not conductive to making bio-oils useful as fuels. Therefore, fast pyrolysis oils should be refined before producing deoxygenated products. After the analysis of pyrolysis oil, the HDO process is reviewed in detail. The HDO of model compounds including phenolics monomers, dimers, furans, carboxylic acids and carbohydrates is summarized to obtain sufficient information in understanding HDO reaction networks and mechanisms. Meanwhile, investigations of model compounds also make sense for screening and designing HDO catalysts. Then, we review the HDO of actual pyrolysis oil with different methods including two-stage treatment, co-feeding solvents and in-situ hydrogenation. The relative merits of each method are also expounded. Finally, HDO catalysts are reviewed in order of time. After the summarization of petroleum derived sulfured catalysts and noble metal catalysts, transitional metal carbide, nitride and phosphide materials are summarized as the new trend for their low cost and high stability. After major progress is reviewed, main problems are summarized and possible solutions are raised.
      PubDate: 2017-06-01
      DOI: 10.3390/catal7060169
      Issue No: Vol. 7, No. 6 (2017)
       
  • Catalysts, Vol. 7, Pages 170: Mechanocatalytic Production of Lactic Acid
           from Glucose by Ball Milling

    • Authors: Luyang Li, Lulu Yan, Feng Shen, Mo Qiu, Xinhua Qi
      First page: 170
      Abstract: A solvent-free process was developed for the direct production of lactic acid from glucose in a mechanocatalytic process in the presence of Ba(OH)2, and a moderate lactic acid yield of 35.6% was obtained. Glucose conversion and lactic acid formation were favorable at higher catalyst/glucose mass ratios. However, at relatively lower catalyst/glucose mass ratios, they were greatly inhibited, and the promotion of fructose formation was observed. The mechanocatalytic process was applicable for various carbohydrates such as C5 sugars, C6 sugars, and disaccharides with 20–36% lactic acid yields achieved. This work provides a new pathway for the production of value-added chemicals from biomass resources.
      PubDate: 2017-06-01
      DOI: 10.3390/catal7060170
      Issue No: Vol. 7, No. 6 (2017)
       
  • Catalysts, Vol. 7, Pages 171: Near-Graphite Coke Deposit on Nano-HZSM-5
           Aggregates for Methanol to Propylene and Butylene Reaction

    • Authors: Yu Sang, Aihua Xing, Chuanfu Wang, Zhihua Han, Yulong Wu
      First page: 171
      Abstract: Nanocrystal HZSM-5 zeolite aggregates with different SiO2/Al2O3 molar ratios were prepared under low temperature and were used to catalyze the conversion of methanol to propylene and butene. The coke location, coke content, and coke species deposited on HZSM-5 aggregates were investigated. The near-graphite carbon on the external surface of HZSM-5 zeolite (SiO2/Al2O3 molar ratio = 400) was distinguished by transmission electron microscopy (TEM) and energy dispersive spectrometer (EDS). The carbon distributions in the micropores and on the external surface of the spent HZSM-5 were revealed by thermogravimetric analysis (TGA) and Brunauer-Emmett-Teller (BET) results. Coke preferred to deposit in the mircopores of low SiO2/Al2O3 molar ratio samples (200, 300) with relatively uniform Al distribution, while coke also preferred to deposit on the external surface and in the intergranular spaces of high SiO2/Al2O3 molar ratio sample (400) with an obviously poor Al core and rich Al shell.
      PubDate: 2017-06-01
      DOI: 10.3390/catal7060171
      Issue No: Vol. 7, No. 6 (2017)
       
  • Catalysts, Vol. 7, Pages 172: Imidazoles-Intercalated α-Zirconium
           Phosphate as Latent Thermal Initiators in the Reaction of Glycidyl Phenyl
           Ether (GPE) and Hexahydro-4-Methylphthalic Anhydride (MHHPA)

    • Authors: Osamu Shimomura, Kensuke Tokizane, Takatoshi Nishisako, Shunro Yamaguchi, Junko Ichihara, Manabu Kirino, Atsushi Ohtaka, Ryôki Nomura
      First page: 172
      Abstract: The capabilities of imidazoles-intercalated α-zirconium phosphate (α-ZrP·imidazole): imidazol (α-ZrP·Im), 2-methylimidazole (α-ZrP·2MIm), and 2-ethyl-4-methylimidazole (α-ZrP·2E4MIm) as latent thermal initiators were examined by the copolymerization of glycidyl phenyl ether (GPE) and hexahydro-4-methylphthalic anhydride (MHHPA) with the imidazoles-intercalated α-zirconium phosphate at varying temperatures for one-hour periods. Polymerization was not observed until the reactants were heated to 100 °C or above. Increasing the temperature, polymerization in the presence of α-ZrP·Im, α-ZrP·2MIm, or α-ZrP·2E4MIm proceeded at 140 °C for 1 h with over 90% conversion. The thermal stabilities of α-ZrP·Im, α-ZrP·2MIm, and α-ZrP·2E4MIm in the reaction at 40 °C for 264 h were tested. With α-ZrP·2MIm, the conversion was less than 15% up to 96 h. In the cases of α-ZrP·Im and α-ZrP·2E4MIm, the conversion reached less than 15% at 264 h. The thermal stabilities of α-ZrP·Im, α-ZrP·2MIm, and α-ZrP·2E4MIm at 40 °C were superior to those of the commercially available thermal latent initiators: HX-3088 and HX-3722.
      PubDate: 2017-06-01
      DOI: 10.3390/catal7060172
      Issue No: Vol. 7, No. 6 (2017)
       
  • Catalysts, Vol. 7, Pages 173: Unconventional Approaches Involving
           Cyclodextrin-Based, Self-Assembly-Driven Processes for the Conversion of
           Organic Substrates in Aqueous Biphasic Catalysis

    • Authors: Frédéric Hapiot, Eric Monflier
      First page: 173
      Abstract: Aqueous biphasic catalysis is a convenient approach to convert organic, partially soluble molecules in water. However, converting more hydrophobic substrates is much more challenging as their solubility in water is extremely low. During the past ten years, substantial progress has been made towards improving the contact between hydrophobic substrates and a hydrophilic transition-metal catalyst. The main cutting-edge approaches developed in the field by using cyclodextrins as a supramolecular tool will be discussed and compared in this short review.
      PubDate: 2017-06-02
      DOI: 10.3390/catal7060173
      Issue No: Vol. 7, No. 6 (2017)
       
  • Catalysts, Vol. 7, Pages 174: Nanostructured Ceria-Based Materials: Effect
           of the Hydrothermal Synthesis Conditions on the Structural Properties and
           Catalytic Activity

    • Authors: Marco Piumetti, Samir Bensaid, Tahrizi Andana, Melodj Dosa, Chiara Novara, Fabrizio Giorgis, Nunzio Russo, Debora Fino
      First page: 174
      Abstract: In this work, several nanostructured ceria catalysts were prepared by means of a hydrothermal procedure, in which the synthesis conditions (i.e., temperature and pH values) were varied. CeO2 samples of different shapes and structural properties were obtained, namely cubes, rods, cube and nanorod mixtures, and other polyhedra. The prepared materials were tested using four probe catalytic reactions: CO oxidation, NO oxidation, NOx-free soot oxidation, and NOx-assisted soot oxidation. The physicochemical properties of the prepared catalysts were studied by means of complementary techniques (i.e., XRD, N2-physisorption at −196 °C, CO-TPR (temperature-programmed reduction), field emission scanning electron microscopy (FESEM), micro-Raman spectroscopy). The abundance of defects of the catalysts, measured through in-situ Raman spectroscopy at the typical temperatures of each catalytic process, was correlated to the CO and NO oxidation activity of the prepared catalysts, while the soot oxidation reaction (performed in loose conditions), which was hindered by a poor soot-catalyst contact, was found to be less sensitive to the observed structural defects.
      PubDate: 2017-06-02
      DOI: 10.3390/catal7060174
      Issue No: Vol. 7, No. 6 (2017)
       
  • Catalysts, Vol. 7, Pages 175: Carbon-Modified Mesoporous Anatase/TiO2(B)
           Whisker for Enhanced Activity in Direct Synthesis of Hydrogen Peroxide by
           Palladium

    • Authors: Rui Tu, Licheng Li, Suoying Zhang, Shuying Chen, Jun Li, Xiaohua Lu
      First page: 175
      Abstract: The regulation of the interaction between H2O2 and its catalysts is a promising route to achieve high productivity and selectivity towards H2O2. Herein, mesoporous anatase/TiO2(B) whisker (mb-TiO2) modified with heterogeneous carbon was prepared as the support of Pd-based catalysts for the direct synthesis of H2O2. The morphology and structure of the catalyst were investigated by transmission electron microscopy, X-ray diffraction, Raman spectroscopy, Brunner-Emmet-Teller measurements, and X-ray photoelectron spectroscopy. The interaction between H2O2 and the support was studied by isothermal calorimeter. The carbon heterogeneous modification can weaken the interaction between H2O2 and the support, then accelerate the desorption of H2O2 and reduce the re-adsorption of H2O2 in the reaction medium. Meanwhile, the synergistic effects between TiO2 and Pd nanoparticles are not influenced by the heterogeneous carbon distribution. The catalyst exhibits better performance for the synthesis of H2O2 compared with the corresponding unmodified catalyst; the productivity of H2O2 increases more than 40%, which can be ascribed to the decrease of further H2O2 conversion under the weakened interaction.
      PubDate: 2017-06-02
      DOI: 10.3390/catal7060175
      Issue No: Vol. 7, No. 6 (2017)
       
  • Catalysts, Vol. 7, Pages 176: Zirconium Phosphate Heterostructures as
           Catalyst Support in Hydrodeoxygenation Reactions

    • Authors: Daniel Ballesteros-Plata, Antonia Infantes-Molina, Elena Rodríguez-Aguado, Pilar Braos-García, José Jiménez-Jiménez, Enrique Rodríguez-Castellón
      First page: 176
      Abstract: A porous phosphate heterostructure (PPHs) formed by a layered zirconium(IV) phosphate expanded with silica galleries was prepared presenting a P/Zr molar ratio equal to 2 and a (Si + Zr)/P ratio equal to 3. This pillared zirconium phosphate heterostructure was used as a catalyst support for bi-functional catalysts based on noble metals (Pt or Pd) and molybdenum oxide containing a total metallic loading of 2 wt % and Pt(Pd)/Mo molar ratio equal to 1. The catalysts prepared were characterized by different experimental techniques and evaluated in the hydrodeoxygenation (HDO) reaction of dibenzofuran (DBF) as a model compound present in biomass derived bio-oil, at different reaction pressures. The catalyst characterization evidenced that a high dispersion of the active phase can be achieved by using these materials, as observed from transmission electron microscopy (TEM) characterization, where the presence of small particles in the nanometric scale is noticeable. Moreover, the textural and acidic properties of the phosphate heterostructure are barely affected by the incorporation of metals into its structure. Characterization results evidenced that the presented material is a good candidate to be used as a material support. In both cases, high conversions and high selectivities to deoxygenated compounds were achieved and the active phase played an important role. Thus, Pt/Mo presented a better hydrogenolysis capability, being more selective to O-free products; whereas, Pd/Mo showed a greater hydrogenation ability being more affected by changes in pressure conditions.
      PubDate: 2017-06-02
      DOI: 10.3390/catal7060176
      Issue No: Vol. 7, No. 6 (2017)
       
  • Catalysts, Vol. 7, Pages 177: A Reusable Palladium/Cationic
           2,2′-Bipyridyl System-Catalyzed Double Mizoroki-Heck Reaction in Water

    • Authors: Yu-Chi Chen, Chien-Chi Wu, Wei-Ting Liao, Ling-Jun Liu, Fu-Yu Tsai
      First page: 177
      Abstract: A reusable PdCl2(NH3)2/cationic 2,2′-bipyridyl system was used to catalyze the double Mizoroki-Heck reaction of aryl iodides with electron-deficient alkenes in water in the absence of inert gas, giving β,β-diarylated carbonyl derivatives in good to excellent yields. The formation of unsymmetrical β,β-diarylated alkenes were also studied by coupling aryl iodides with the corresponding aryl-substituted α,β-unsaturated carbonyl compounds. This water-soluble catalyst can be swiftly separated from the organic layer using simple extraction for the further reuse, and, thus, makes it an operationally-simple and environmentally-benign procedure.
      PubDate: 2017-06-02
      DOI: 10.3390/catal7060177
      Issue No: Vol. 7, No. 6 (2017)
       
  • Catalysts, Vol. 7, Pages 178: Immobilization of Lipases on Magnetic
           Collagen Fibers and Its Applications for Short-Chain Ester Synthesis

    • Authors: Shengsheng He, Dewei Song, Min Chen, Haiming Cheng
      First page: 178
      Abstract: Magnetic nanoparticles (MNp) Fe3O4 were prepared by chemical coprecipitation, and introduced onto collagen fibers to form magnetic collagen support (MNp-Col) for enzyme immobilization. Candida rugosa lipase has been successfully immobilized on MNp-Col supports by a covalent bond cross-linking agent, glutaraldehyde. The characteristics of MNp-Col and the immobilized lipase were investigated. The immobilized lipase displayed sound magnetic separation abilities in both aqueous and organic media. The activity of the immobilized lipase reached 2390 U/g under optimal conditions. The MNp-Col immobilized lipase shows broadened temperature and pH ranges for hydrolysis of olive oil emulsion. For synthesis of butyrate esters in an n-hexane medium, the yield changes through use of different alcohols, among which, butyric butyrate showed the highest yield. The prepared magnetic collagen fiber provides separation support for enzyme immobilization and has the potential to be used in other biotechnology fields.
      PubDate: 2017-06-07
      DOI: 10.3390/catal7060178
      Issue No: Vol. 7, No. 6 (2017)
       
  • Catalysts, Vol. 7, Pages 179: Conversion of Furans by Baeyer-Villiger
           Monooxygenases

    • Authors: Hemant Kumar, Marco Fraaije
      First page: 179
      Abstract: Various furans are considered as valuable platform chemicals as they can be derived from plant biomass. Yet, for their exploitation, follow-up chemistry is required. Here we demonstrate that Baeyer-Villiger monooxygenases (BVMOs) can be used as biocatalysts for the selective oxidation of several furans, including 5-(hydroxymethyl) furfural (HMF) and furfural. A total of 15 different BVMOs were tested for their activity on furfural, which revealed that most of the biocatalysts were active on this aromatic aldehyde. Phenylacetone monooxygenase (PAMO) and a mutant thereof (PAMOM446G) were selected for studying their biocatalytic potential in converting furfural and some other furans. While BVMOs are usually known to form an ester or lactone as a ‘normal’ product by inserting an oxygen atom adjacent to the carbonyl carbon of the substrate, our results reveal that both biocatalysts produce furanoid acids as the main product from the corresponding aldehydes. Altogether, our study shows that BVMOs can be employed for the selective oxidation of furans.
      PubDate: 2017-06-07
      DOI: 10.3390/catal7060179
      Issue No: Vol. 7, No. 6 (2017)
       
  • Catalysts, Vol. 7, Pages 180: Preparation of ZnO-Loaded Lignin-Based
           Carbon Fiber for the Electrocatalytic Oxidation of Hydroquinone

    • Authors: Yuexing Wei, Min Song, Lei Yu, Xinhong Tang
      First page: 180
      Abstract: To improve the hydroquinone (HQ) determination limit in wastewater and contribute to the comprehensive utilization of lignin, a zinc oxide-loaded lignin-based carbon fiber (ZCF) was prepared by a combination of electrospinning and thermal treatment processes, and was applied in electrocatalytic oxidation of HQ using cyclic voltammetry (CV). The characterization of composites was conducted by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectrometer (EDS). The CV curves demonstrate that a ZCF-modified electrode can efficiently enhance the electrochemical signal and provide a fast response to HQ with a linear range from 1 × 10−6 to 5 × 10−3 mol/L and a determination limit of 2.5 × 10−7 M. Compared with modification materials reported in other literature, it performs excellent. In addition, the effect of the scan rate and the stability of modified materials were also investigated to illustrate the electrochemical behavior on HQ determination. Under optimum conditions, the ZCF-modified electrode was also used for the simultaneous determination of HQ, catechol (CC), and resorcinol (RS), which could well separate the oxidation peaks of the three isomers.
      PubDate: 2017-06-08
      DOI: 10.3390/catal7060180
      Issue No: Vol. 7, No. 6 (2017)
       
  • Catalysts, Vol. 7, Pages 181: Effect of Ce/Y Addition on Low-Temperature
           SCR Activity and SO2 and H2O Resistance of MnOx/ZrO2/MWCNTs Catalysts

    • Authors: Lifu Dong, Yinming Fan, Wei Ling, Chao Yang, Bichun Huang
      First page: 181
      Abstract: The effects of SO2 and H2O on the low-temperature selective catalytic reduction (SCR) activity over MnOx/ZrO2/MWCNTs and MnOx/ZrO2/MWCNTs catalysts modified by Ce or Y was studied. MnCeZr and MnYZr catalysts reached nearly 100% and 93.9% NOx conversions at 200 °C and 240 °C, respectively. They displayed a better SO2 tolerance, and the effect of H2O was negligible. The structural properties of the catalysts were characterized by XRD, H2-TPR, XPS, and FTIR before and after the reaction. The results showed that Ce could increase the mobility of the oxygen and improve the valence and the oxidizability of manganese, while the effect of Y was the opposite. This might be the main reason why the catalytic activity of MnCeZr was better than MnYZr in the presence or absence of SO2 and H2O. Doping Ce or Y broadened the active temperature window. Ce or Y, which existed in the catalysts with a high dispersion or at the amorphous state, preferred to react with SO2 to form sulfate species, and protected the manganese active sites from combing with SO2 to some extent, which coincided with the theory of ionic polarization.
      PubDate: 2017-06-08
      DOI: 10.3390/catal7060181
      Issue No: Vol. 7, No. 6 (2017)
       
  • Catalysts, Vol. 7, Pages 182: Insights into the Metal Salt Catalyzed
           5-Ethoxymethylfurfural Synthesis from Carbohydrates

    • Authors: Xin Yu, Xueying Gao, Ruili Tao, Lincai Peng
      First page: 182
      Abstract: The use of common metal salts as catalysts for 5-ethoxymethylfurfural (EMF) synthesis from carbohydrate transformation was performed. Initial screening suggested AlCl3 as an efficient catalyst for EMF synthesis (45.0%) from fructose at 140 °C. Interestingly, CuSO4 and Fe2(SO4)3 were found to yield comparable EMF at lower temperature of 110 to 120 °C, and high yields of ethyl levulinate (65.4–71.8%) were obtained at 150 °C. However, these sulfate salts were inactive in EMF synthesis from glucose and the major product was ethyl glucoside with around 80% yield, whereas EMF of 15.2% yield could be produced from glucose using CrCl3. The conversion of sucrose followed the accumulation of the reaction pathways of fructose and glucose, and a moderate yield of EMF could be achieved.
      PubDate: 2017-06-08
      DOI: 10.3390/catal7060182
      Issue No: Vol. 7, No. 6 (2017)
       
  • Catalysts, Vol. 7, Pages 183: Review on Copper and Palladium Based
           Catalysts for Methanol Steam Reforming to Produce Hydrogen

    • Authors: Xinhai Xu, Kaipeng Shuai, Ben Xu
      First page: 183
      Abstract: Methanol steam reforming is a promising technology for producing hydrogen for onboard fuel cell applications. The methanol conversion rate and the contents of hydrogen, carbon monoxide and carbon dioxide in the reformate, significantly depend on the reforming catalyst. Copper-based catalysts and palladium-based catalysts can effectively convert methanol into hydrogen and carbon dioxide. Copper and palladium-based catalysts with different formulations and compositions have been thoroughly investigated in the literature. This work summarized the development of the two groups of catalysts for methanol steam reforming. Interactions between the activity components and the supports as well as the effects of different promoters were discussed. Compositional and morphological characteristics, along with the methanol steam reforming performances of different Cu/ZnO and Pd/ZnO catalysts promoted by Al2O3, CeO2, ZrO2 or other metal oxides, were reviewed and compared. Moreover, the reaction mechanism of methanol steam reforming over the copper based and palladium based catalysts were discussed.
      PubDate: 2017-06-08
      DOI: 10.3390/catal7060183
      Issue No: Vol. 7, No. 6 (2017)
       
  • Catalysts, Vol. 7, Pages 184: Catalytic Acetalization: An Efficient
           Strategy for High-Value Utilization of Biodiesel-Derived Glycerol

    • Authors: Suqun Sun, Min He, Yuanwei Dai, Xin Li, Zhijun Liu, Li Yao
      First page: 184
      Abstract: In this study, an efficient process for high value utilization of biodiesel-derived glycerol was proposed via a simple reaction of acetalization catalyzed by novel catalysts of ester sulfate-functionalized ionic liquids (ILs). The relationship between the IL structure and its catalytic activity was investigated. The effects of reaction conditions, and the substrate adaptability, were also carefully studied. The results demonstrate that ester sulfate-functionalized IL shows excellent catalytic activity on the acetalization of glycerol with aldehyde (ketone). Under the optimized condition, 87% glycerol conversion was obtained with 99% acetal selectivity when glycerol was condensed with cyclohexanone. In particular, 29% of product consists of six-membered compound, an important fine chemical and an excellent precursor in organic chemistry, because of the significant steric-hindrance effect of IL catalyst. Furthermore, the IL catalyst shows good recyclability where insignificant activity loss was exhibited even after six runs.
      PubDate: 2017-06-08
      DOI: 10.3390/catal7060184
      Issue No: Vol. 7, No. 6 (2017)
       
  • Catalysts, Vol. 7, Pages 185: Lipase-Catalyzed Synthesis of Indolyl
           4H-Chromenes via a Multicomponent Reaction in Ionic Liquid

    • Authors: Weian Zhang, Ziyuan Zhao, Zhi Wang, Chao Guo, Chunyu Wang, Rui Zhao, Lei Wang
      First page: 185
      Abstract: Synthesis of indolyl 4H-chromenes via a three-component reaction catalyzed by lipase in ionic liquidsis reported here for the first time. High yields (77–98%) were obtained when Mucor miehei lipase was used as the catalyst in [EMIM][BF4]. Furthermore, [EMIM][BF4] exhibited good reusability in this enzymatic reaction. This study affords a new example of lipase catalytic promiscuity and broadens the application range of ionic liquid in biocatalysis.
      PubDate: 2017-06-08
      DOI: 10.3390/catal7060185
      Issue No: Vol. 7, No. 6 (2017)
       
  • Catalysts, Vol. 7, Pages 186: Immobilized Palladium Nanoparticles on
           Zirconium Carboxy-Aminophosphonates Nanosheets as an Efficient Recoverable
           Heterogeneous Catalyst for Suzuki–Miyaura and Heck Coupling

    • Authors: Vadym Kozell, Tommaso Giannoni, Morena Nocchetti, Riccardo Vivani, Oriana Piermatti, Luigi Vaccaro
      First page: 186
      Abstract: Zirconium phosphate glycine diphosphonate nanosheets (ZPGly) have been used as support for the preparation of solid palladium nanoparticles, namely Pd@ZPGly. Thanks to the presence of carboxy-aminophosponate groups on the layer surface, ZPGly-based materials were able to stabilize a high amount of palladium (up to 22 wt %) also minimizing the amount of metal leached in the final products of representative important cross-coupling processes selected for proving the catalysts’ efficiency. The catalytic systems have been fully characterized and used in low amounts (0.1 mol %) in the Suzuki–Miyaura and Heck cross-couplings. Moreover, the protocols were optimized for the use of recoverable azeotropic mixtures (aq. EtOH 96% or aq. CH3CN 84%, respectively) and in the flow procedure allowing one to isolate the final pure products, without any purification step, with very low residual palladium content and with a very low waste production.
      PubDate: 2017-06-09
      DOI: 10.3390/catal7060186
      Issue No: Vol. 7, No. 6 (2017)
       
  • Catalysts, Vol. 7, Pages 187: Potential of Pervaporation and Vapor
           Separation with Water Selective Membranes for an Optimized Production of
           Biofuels—A Review

    • Authors: Catia Cannilla, Giuseppe Bonura, Francesco Frusteri
      First page: 187
      Abstract: The development of processes based on the integration of new technologies is of growing interest to industrial catalysis. Recently, significant efforts have been focused on the design of catalytic membrane reactors to improve process performance. In particular, the use of membranes, that allow a selective permeation of water from the reaction mixture, positively affects the reaction evolution by improving conversion for all reactions thermodynamically or kinetically limited by the presence of water. In this paper, how pervaporation (PV) and vapor permeation (VP) technologies can improve the catalytic performance of reactions of industrial interest is considered. Specifically, technological approaches proposed in the literature are discussed with the aim of highlighting advantages and problems encountered in order to address research towards the optimization of membrane reactor configurations for liquid biofuel production in large scale.
      PubDate: 2017-06-09
      DOI: 10.3390/catal7060187
      Issue No: Vol. 7, No. 6 (2017)
       
  • Catalysts, Vol. 7, Pages 188: Using Laccases in the Nanoflower to
           Synthesize Viniferin

    • Authors: Zhuofu Wu, Heng Li, XueJun Zhu, Shuai Li, Zhi Wang, Lei Wang, Zhengqiang Li, Guang Chen
      First page: 188
      Abstract: The laccase-incorporated nanoflower was fabricated and characterized by scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR). SEM images indicate that the laccase-incorporated nanoflower has a high surface area, which may facilitate the mass transfer of the substrate and the product. FTIR spectrums identify the existence of laccase in the nanoflowers. The novel immobilized laccase was used for the synthesis of viniferin. The reaction conditions had been optimized and the laccase-incorporated nanoflower can show its maximum specific activity (16.3 µmol/g/h) under the optimal reaction conditions. The specific activity of the laccase in the nanoflowers is enhanced about 2.2-fold compared with free laccase in solution without copper (II) ions. Furthermore, the laccase in the nanoflowers shows an increase in specific activity of ~180% compared with free laccase in a solution containing high concentrations (similar to the concentration in the flower) of copper (II) ions. The results also indicate that the laccase in the nanoflowers retain 93.2% of its initial specific activity even after ten continuous batches.
      PubDate: 2017-06-12
      DOI: 10.3390/catal7060188
      Issue No: Vol. 7, No. 6 (2017)
       
  • Catalysts, Vol. 7, Pages 189: Co3O4 Nanoparticle-Decorated N-Doped
           Mesoporous Carbon Nanofibers as an Efficient Catalyst for Oxygen Reduction
           Reaction

    • Authors: Hairong Xue, Tao Wang, Hao Gong, Hu Guo, Xiaoli Fan, Li Song, Wei Xia, Yaya Feng, Jianping He
      First page: 189
      Abstract: A low cost, durable, and efficient electrocatalyst for oxygen reduction reactions (ORR) is essential for high-performance fuel cells. Here, we fabricated Co3O4 nanoparticles (NPs) anchored on N-doped mesoporous carbon nanofibers (Co3O4/NMCF) by electrospinning combined with the simple heat treatment. Within this composite, carbon nanofibers possess a mesoporous structure, contributed to obtain a high surface area, which can facilitate the infiltration of electrolyte. Moreover, this one-dimensional (1D) carbon nanofiber also acts as a 1D conductive channel, effectively improving the transmission of electrons. In addition, the doping of the N element with high content combined with homogenously distributed Co3O4 NPs can significantly enhance the ORR electrocatalytic activity. Benefiting from the advantages of material and structure, the Co3O4/NMCF catalyst favors a four electron transfer process in alkaline media, exhibiting good ORR electrocatalytic activity, and its durability is much better than that of commercial Pt/C.
      PubDate: 2017-06-15
      DOI: 10.3390/catal7060189
      Issue No: Vol. 7, No. 6 (2017)
       
  • Catalysts, Vol. 7, Pages 190: Zirconium Phosphate Catalysts in the XXI
           Century: State of the Art from 2010 to Date

    • Authors: Monica Pica
      First page: 190
      Abstract: An overview on the developments of zirconium phosphate (ZrP) and its organic derivatives in heterogeneous catalysis in recent years is reported in the present review. Two basic aspects have been emphasized: first, the catalytic properties of zirconium phosphates were discussed, with particular attention to the effect of surface acidity and hydrophobic/hydrophilic character, textural properties, and particle morphology on the catalytic performances. Then, the use of zirconium phosphates as support for catalytic active species was reported, including organometallic complexes, metal ions, noble metal, and metal oxide nanoparticles. Zirconium phosphate plays, in those cases, a dual role, since it promotes the dispersion and stabilization of the catalysts, thanks to their interaction with the active sites on the surface of ZrP, and facilitates the recovery and reuse of the catalytic species due to their immobilization on the solid support.
      PubDate: 2017-06-19
      DOI: 10.3390/catal7060190
      Issue No: Vol. 7, No. 6 (2017)
       
  • Catalysts, Vol. 7, Pages 191: A Theoretical Insight into Enhanced
           Catalytic Activity of Au by Multiple Twin Nanoparticles

    • Authors: Kyoichi Sawabe, Taiki Koketsu, Junya Ohyama, Atsushi Satsuma
      First page: 191
      Abstract: Recently, it has been reported that the morphology of Au nanoparticles (NPs) affects the catalytic activity of CO oxidation; twin crystal NPs show higher activity for CO oxidation than single-crystal NPs. In this study, density functional calculations have been carried out to investigate the morphology effect of Au NPs using CO as a probe molecule. In the case of Au NPs with a size of more than 2 nm, CO adsorption energy on the Au NPs is mainly determined by a coordination number (CN) of adsorption sites. CO binding to a multiple twin NP with a size of about 1 nm is stronger than that on a single-crystal NP with the same size. A simple CN explanation cannot be applied to the enhancement of CO binding to the small multiple twin NP. This enhancement is related to a deformation of the NP structure before and after CO adsorption. It is suggested that the multiple twin NP with a size of less than 1 nm, which shows the deformation upon CO adsorption, contributes to the higher activity for CO oxidation.
      PubDate: 2017-06-19
      DOI: 10.3390/catal7060191
      Issue No: Vol. 7, No. 6 (2017)
       
  • Catalysts, Vol. 7, Pages 192: l-Amino Acid Production by a Immobilized
           Double-Racemase Hydantoinase Process: Improvement and Comparison with a
           Free Protein System

    • Authors: María Rodríguez-Alonso, Felipe Rodríguez-Vico, Francisco Las Heras-Vázquez, Josefa Clemente-Jiménez
      First page: 192
      Abstract: Protein immobilization is proving to be an environmentally friendly strategy for manufacturing biochemicals at high yields and low production costs. This work describes the optimization of the so-called “double-racemase hydantoinase process,” a system of four enzymes used to produce optically pure l-amino acids from a racemic mixture of hydantoins. The four proteins were immobilized separately, and, based on their specific activity, the optimal whole relation was determined. The first enzyme, d,l-hydantoinase, preferably hydrolyzes d-hydantoins from d,l-hydantoins to N-carbamoyl-d-amino acids. The remaining l-hydantoins are racemized by the second enzyme, hydantoin racemase, and continue supplying substrate d-hydantoins to the first enzyme. N-carbamoyl-d-amino acid is racemized in turn to N-carbamoyl-l-amino acid by the third enzyme, carbamoyl racemase. Finally, the N-carbamoyl-l-amino acid is transformed to l-amino acid by the fourth enzyme, l-carbamoylase. Therefore, the product of one enzyme is the substrate of another. Perfect coordination of the four activities is necessary to avoid the accumulation of reaction intermediates and to achieve an adequate rate for commercial purposes. The system has shown a broad pH optimum of 7–9, with a maximum activity at 8 and an optimal temperature of 60 °C. Comparison of the immobilized system with the free protein system showed that the reaction velocity increased for the production of norvaline, norleucine, ABA, and homophenylalanine, while it decreased for l-valine and remained unchanged for l-methionine.
      PubDate: 2017-06-20
      DOI: 10.3390/catal7060192
      Issue No: Vol. 7, No. 6 (2017)
       
  • Catalysts, Vol. 7, Pages 126: Ion-Exchange of Cu2+ Promoted Layered
           Perovskite K2La2Ti3O10 for Photocatalytic Degradation Chlorobenzene under
           Simulated Solar Light Irradiation

    • Authors: Dandan Pang, Jie Gao, Feng Ouyang, Rongshu Zhu, Charlene Xie
      First page: 126
      Abstract: The layered perovskite, K2La2Ti3O10 was prepared by sol-gel method. Ion-exchange of Cu2+ was prepared to improve the photocatalytic activity of K2La2Ti3O10 for chlorobenzene degradation under simulated solar light irradiation. The original K2La2Ti3O10 and Cu2+/K2La2Ti3O10 were characterized by power X-ray diffraction, UV-visible diffuse reflectance spectroscopy, and specific surface area measurement. The XRD analysis shows that Cu2+ ions is incorporated in place of K+ ions and the grain growth is inhibited by ion-exchange. With the rise of calcination temperature, more interlayer Cu2+ was converted into new crystal phase CuO. The degradation ratio reaches 51.1% on Cu2+/K2La2Ti3O10 calcined at 500 °C in air, which is higher 16.9% than the original K2La2Ti3O10. It should be ascribed to the narrow interlayer distance, the formation of CuO, smaller grain size, and the high visible light absorption on the surface of Cu2+/K2La2Ti3O10 calcined at 500 °C. It is found that the exposure of CO2 could promote the photocatalytic activity of Cu2+/K2La2Ti3O10. It also suggests that CO2 is involved in the reduction to form benzaldehyde during decomposition of chlorobenzene.
      PubDate: 2017-04-26
      DOI: 10.3390/catal7050126
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 127: Well-Shaped Sulfonic Organosilica Nanotubes
           with High Activity for Hydrolysis of Cellobiose

    • Authors: Jing Sun, Xiao Liu, Xinli Zhu, Hua Wang, Sadegh Rostamnia, Jinyu Han
      First page: 127
      Abstract: Sulfonic organosilica nanotubes with different acidity densities could be synthesized through the co-condensation of ethenyl- or phenylene-bridged organosilane and 3-mercaptopropyltrimethoxysilane followed by sulfhydryl (–SH) oxidation. Transmission electron microscopy (TEM) analysis and nitrogen adsorption-desorption experiment clearly exhibit the hollow nanotube structures with the diameters of about 5 nm. The compositions of the nanotube frameworks are confirmed by solid state 13C nuclear magnetic resonance (NMR) while X-ray photoelectron spectroscopy (XPS) shows that about 60–80% of SH groups were oxidized to sulfonic acid (SO3H). The acid contents were measured by both elemental analysis (CHNS mode) and acid-base titration experiment, which revealed that the acid density was in the range of 0.74 to 4.37 μmol·m−2 on the solid. These nanotube-based acid catalysts exhibited excellent performances in the hydrolysis of cellobiose with the highest conversion of 92% and glucose selectivity of 96%. In addition, the catalysts could maintain high activity (65% conversion with 92% selectivity) even after six recycles.
      PubDate: 2017-04-27
      DOI: 10.3390/catal7050127
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 128: Highly Dispersed PdNPs/α-Al2O3 Catalyst for
           the Selective Hydrogenation of Acetylene Prepared with Monodispersed Pd
           Nanoparticles

    • Authors: Huoli Zhang, Youchao Wang, Yan Wang, Jianliang Cao, Peng Kang, Qingjie Tang, Mingjie Ma
      First page: 128
      Abstract: Pd nanoparticles (PdNPs) stabilized by methyl cellulose (MC) were synthesized in an aqueous solution, which are monodispersed nanoparticles. PdNPs/α-Al2O3 catalyst was prepared with monodispersed PdNPs and showed better catalytic performance than Pd/α-Al2O3 catalyst prepared by the incipient wetness impregnation method using Pd(NO3)2 as a precursor. The catalysts were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD) and inductively coupled plasma mass spectrometry (ICP-MS). It was found that monodispersed PdNPs were spherical or elliptical nanoparticles with exposed (111) and (100) facets, and the PdNPs/α-Al2O3 catalyst showed a more concentrated distribution of Pd particles on the surface of α-Al2O3 support than the Pd/α-Al2O3 catalyst. The preparation method achieved the highly dispersed PdNPs/α-Al2O3 catalyst with smaller Pd particle size and decreased the aggregation of Pd active sites, which was responsible for higher acetylene conversion and ethylene selectivity.
      PubDate: 2017-04-28
      DOI: 10.3390/catal7050128
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 129: A Study of Low-Temperature CO Oxidation over
           Mesoporous CuO-TiO2 Nanotube Catalysts

    • Authors: Abdallah Zedan, Nageh Allam, Siham AlQaradawi
      First page: 129
      Abstract: Supported copper oxide nanoparticles have attracted considerable attention as active and non-precious catalysts for many catalytic oxidation reactions. Herein, mesoporous xCuO-TiO2 nanotube catalysts were fabricated, and their activity and kinetics toward CO oxidation were studied. The morphology and structure of the prepared catalysts were systematically studied using SEM, TEM, EDS, EDX, XRD, TGA, BET, XPS, H2-TPR, and Raman techniques. The BET surface area study revealed the effect of the large surface area of the mesoporous TiO2 nanotubes on promoting the catalytic activity of prepared catalysts. The results also revealed the existence of strong metal-support interactions in the CuO-TiO2 nanotube catalyst, as indicated by the up-shift of the E2g vibrational mode of TiO2 from 144 cm−1 to 145 cm−1 and the down-shift of the binding energy (BE) of Ti 2p3/2 from 458.3 eV to 458.1 eV. The active phase of the catalyst consists of fine CuO nanoparticles dispersed on a mesoporous anatase TiO2 nanotube support. The 50-CuO-TiO2 nanotube catalyst demonstrated the highest catalytic activity with 100% CO conversion at T100 = 155 °C and a reaction rate of 36 µmole s−1 g−1. Furthermore, the catalyst demonstrated excellent long-term stability with complete CO conversion that was stable for 60 h under a continuous stream. The enhanced catalytic activity is attributed to the interplay at the interface between the active CuO phase and the TiO2 nanotubes support.
      PubDate: 2017-04-28
      DOI: 10.3390/catal7050129
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 130: Old Yellow Enzyme-Catalysed Asymmetric
           Hydrogenation: Linking Family Roots with Improved Catalysis

    • Authors: Anika Scholtissek, Dirk Tischler, Adrie Westphal, Willem van Berkel, Caroline Paul
      First page: 130
      Abstract: Asymmetric hydrogenation of activated alkenes catalysed by ene-reductases from the old yellow enzyme family (OYEs) leading to chiral products is of potential interest for industrial processes. OYEs’ dependency on the pyridine nucleotide coenzyme can be circumvented through established artificial hydride donors such as nicotinamide coenzyme biomimetics (NCBs). Several OYEs were found to exhibit higher reduction rates with NCBs. In this review, we describe a new classification of OYEs into three main classes by phylogenetic and structural analysis of characterized OYEs. The family roots are linked with their use as chiral catalysts and their mode of action with NCBs. The link between bioinformatics (sequence analysis), biochemistry (structure–function analysis), and biocatalysis (conversion, enantioselectivity and kinetics) can enable an early classification of a putative ene-reductase and therefore the indication of the binding mode of various activated alkenes.
      PubDate: 2017-04-29
      DOI: 10.3390/catal7050130
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 131: Treatment of Aqueous Bromate by
           Superparamagnetic BiOCl-Mediated Advanced Reduction Process

    • Authors: Xiaowei Liu, Lili Wang, Zhe Sun, Yu Shao, Tingchao Yu
      First page: 131
      Abstract: Bromate ( BrO 3 − ) contamination in drinking water is a growing concern. Advanced reduction processes (ARPs) are reportedly promising in relieving this concern. In this work, UV/superparamagnetic BiOCl (BiOCl loaded onto superparamagnetic hydroxyapatite) assisted with small molecule carboxylic acid (formate, citrate, and acetate), a carboxyl anion radical ( CO 2 • − )-based ARP, was proposed to eliminate aqueous BrO 3 − . Formate and citrate were found to be ideal CO 2 • − precursor, and the latter was found to be safe for practical use. BrO 3 − (10 μg·L−1, WHO guideline for drinking water) can be completely degraded within 3 min under oxygen-free conditions. In this process, BrO 3 − degradation was realized by the reduction of CO 2 • − (major role) and formyloxyl radical (minor role) in bulk solution. The formation mechanism of radicals and the transformation pathway of BrO 3 − were proposed based on data on electron paramagnetic resonance monitoring, competitive kinetics, and degradation product analysis. The process provided a sustainable decontamination performance (<5% deterioration for 10 cycles) and appeared to be more resistant to common electron acceptors (O2, NO 3 − , and Fe3+) than hydrated electron based-ARPs. Phosphate based-superparamagnetic hydroxyapatite, used to support BiOCl in this work, was believed to be applicable for resolving the recycling problem of other metal-containing catalyst.
      PubDate: 2017-05-01
      DOI: 10.3390/catal7050131
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 132: Transition Metal-Modified Zirconium
           Phosphate Electrocatalysts for the Oxygen Evolution Reaction

    • Authors: Joel Sanchez, Mario V. Ramos-Garcés, Ieva Narkeviciute, Jorge L. Colón, Thomas F. Jaramillo
      First page: 132
      Abstract: Zirconium phosphate (ZrP), an inorganic layered nanomaterial, is currently being investigated as a catalyst support for transition metal-based electrocatalysts for the oxygen evolution reaction (OER). Two metal-modified ZrP catalyst systems were synthesized: metal-intercalated ZrP and metal-adsorbed ZrP, each involving Fe(II), Fe(III), Co(II), and Ni(II) cations. Fourier transform infrared spectroscopy, X-ray powder diffraction, thermogravimetric analysis, and X-ray photoelectron spectroscopy were used to characterize the composite materials and confirm the incorporation of the metal cations either between the layers or on the surface of ZrP. Both types of metal-modified systems were examined for their catalytic activity for the OER in 0.1 M KOH solution. All metal-modified ZrP systems were active for the OER. Trends in activity are discussed as a function of the molar ratio in relation to the two types of catalyst systems, resulting in overpotentials for metal-adsorbed ZrP catalysts that were less than, or equal to, their metal-intercalated counterparts.
      PubDate: 2017-05-01
      DOI: 10.3390/catal7050132
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 133: Sol-Gel-Assisted Microwave-Derived Synthesis
           of Anatase Ag/TiO2/GO Nanohybrids toward Efficient Visible Light Phenol
           Degradation

    • Authors: E. H. Alsharaeh, T. Bora, A. Soliman, Faheem Ahmed, G. Bharath, M. G. Ghoniem, Khalid M. Abu-Salah, J. Dutta
      First page: 133
      Abstract: : A simple microwave-assisted (MWI) wet chemical route to synthesize pure anatase phase titanium dioxide (TiO2) nanoparticles (NPs) is reported here using titanium tetrachloride (TiCl4) as starting material. The as-prepared TiO2 NPs were characterized by electron microscopy, X-ray diffraction, UV/visible absorption spectroscopy, and infrared and Raman spectroscopic techniques. Further modification of the anatase TiO2 NPs was carried out by incorporating plasmonic silver (Ag) NPs and graphene oxide (GO) in order to enhance the visible light absorption. The photocatalytic activities of the anatase TiO2, Ag/TiO2, and Ag/TiO2/GO nanocomposites were evaluated under both ultraviolet (UV) and visible light irradiation using phenol as a model contaminant. The presence of Ag NPs was found to play a significant role to define the photocatalytic activity of the Ag/TiO2/GO nanocomposite. It was found that the Ag performed like a sink under UV excitation and stored photo-generated electrons from TiO2, whereas, under visible light excitation, the Ag acted as a photosensitizer enhancing the photocatalytic activity of the nanocomposite. The detailed mechanism was studied based on photocatalytic activities of Ag/TiO2/GO nanocomposites. Therefore, the as-prepared Ag/TiO2/GO nanocomposite was used as photocatalytic materials under both UV and visible light irradiation toward degradation of organic molecules.
      PubDate: 2017-05-01
      DOI: 10.3390/catal7050133
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 134: Dynamic Processes on Gold-Based Catalysts
           Followed by Environmental Microscopies

    • Authors: Eric Genty, Luc Jacobs, Thierry Visart de Bocarmé, Cédric Barroo
      First page: 134
      Abstract: Since the early discovery of the catalytic activity of gold at low temperature, there has been a growing interest in Au and Au-based catalysis for a new class of applications. The complexity of the catalysts currently used ranges from single crystal to 3D structured materials. To improve the efficiency of such catalysts, a better understanding of the catalytic process is required, from both the kinetic and material viewpoints. The understanding of such processes can be achieved using environmental imaging techniques allowing the observation of catalytic processes under reaction conditions, so as to study the systems in conditions as close as possible to industrial conditions. This review focuses on the description of catalytic processes occurring on Au-based catalysts with selected in situ imaging techniques, i.e., PEEM/LEEM, FIM/FEM and E-TEM, allowing a wide range of pressure and material complexity to be covered. These techniques, among others, are applied to unravel the presence of spatiotemporal behaviours, study mass transport and phase separation, determine activation energies of elementary steps, observe the morphological changes of supported nanoparticles, and finally correlate the surface composition with the catalytic reactivity.
      PubDate: 2017-05-01
      DOI: 10.3390/catal7050134
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 135: Functional and Biochemical Analysis of
           Glucose-6-Phosphate Dehydrogenase (G6PD) Variants: Elucidating the
           Molecular Basis of G6PD Deficiency

    • Authors: Saúl Gómez-Manzo, Jaime Marcial-Quino, Daniel Ortega-Cuellar, Hugo Serrano-Posada, Abigail González-Valdez, America Vanoye-Carlo, Beatriz Hernández-Ochoa, Edgar Sierra-Palacios, Adriana Castillo-Villanueva, Horacio Reyes-Vivas
      First page: 135
      Abstract: G6PD deficiency is the most common enzymopathy, leading to alterations in the first step of the pentose phosphate pathway, which interferes with the protection of the erythrocyte against oxidative stress and causes a wide range of clinical symptoms of which hemolysis is one of the most severe. The G6PD deficiency causes several abnormalities that range from asymptomatic individuals to more severe manifestations that can lead to death. Nowadays, only 9.2% of all recognized variants have been related to clinical manifestations. It is important to understand the molecular basis of G6PD deficiency to understand how gene mutations can impact structure, stability, and enzymatic function. In this work, we reviewed and compared the functional and structural data generated through the characterization of 20 G6PD variants using different approaches. These studies showed that severe clinical manifestations of G6PD deficiency were related to mutations that affected the catalytic and structural nicotinamide adenine dinucleotide phosphate (NADPH) binding sites, and suggests that the misfolding or instability of the 3D structure of the protein could compromise the half-life of the protein in the erythrocyte and its activity.
      PubDate: 2017-05-02
      DOI: 10.3390/catal7050135
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 136: Photocatalytic Graphene-TiO2 Thin Films
           Fabricated by Low-Temperature Ultrasonic Vibration-Assisted Spin and Spray
           Coating in a Sol-Gel Process

    • Authors: Fatemeh Zabihi, Mohammad-Reza Ahmadian-Yazdi, Morteza Eslamian
      First page: 136
      Abstract: In this work, we communicate a facile and low temperature synthesis process for the fabrication of graphene-TiO2 photocatalytic composite thin films. A sol-gel chemical route is used to synthesize TiO2 from the precursor solutions and spin and spray coating are used to deposit the films. Excitation of the wet films during the casting process by ultrasonic vibration favorably influences both the sol-gel route and the deposition process, through the following mechanisms. The ultrasound energy imparted to the wet film breaks down the physical bonds of the gel phase. As a result, only a low-temperature post annealing process is required to eliminate the residues to complete the conversion of precursors to TiO2. In addition, ultrasonic vibration creates a nanoscale agitating motion or microstreaming in the liquid film that facilitates mixing of TiO2 and graphene nanosheets. The films made based on the above-mentioned ultrasonic vibration-assisted method and annealed at 150 °C contain both rutile and anatase phases of TiO2, which is the most favorable configuration for photocatalytic applications. The photoinduced and photocatalytic experiments demonstrate effective photocurrent generation and elimination of pollutants by graphene-TiO2 composite thin films fabricated via scalable spray coating and mild temperature processing, the results of which are comparable with those made using lab-scale and energy-intensive processes.
      PubDate: 2017-05-02
      DOI: 10.3390/catal7050136
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 137: Catalytic Abatement of Nitrous Oxide Coupled
           with Ethane Oxydehydrogenation over Mesoporous Cr/Al2O3 Catalyst

    • Authors: Yan Zhang, Suresh Kumar Megarajan, Xia Xu, Jingting Lu, Heqing Jiang
      First page: 137
      Abstract: Waste nitrous oxide (N2O) was utilized as an oxidant for ethane oxydehydrogenation reaction at the temperature range from 450 °C to 700 °C over the mesoporous Cr/Al2O3 catalyst synthesized via the one-pot evaporation-induced self-assembly (EISA) method. The catalyst was characterized by X-ray diffraction, transmission electron microscopy, and nitrogen adsorption-desorption analysis. The obtained mesoporous material with favorable textural property and advantageous thermal stability was investigated as the catalyst for ethane oxydehydrogenation. It was found that the utilization of N2O as an oxidant for the oxydehydrogenation reaction of ethane resulted in simultaneous and complete N2O abatement. Moreover, the catalytic conversion of C2H6 to C2H4 was increased from 18% to 43% as the temperature increased from 450 °C to 700 °C. The increased N2O concentration from 5 vol % to 20 vol % resulted in an increased ethane conversion but decreased ethylene selectivity because the nonselective reactions occurred. Ethane was converted into ethylene with approximately 51% selectivity and 22% yield at 700 °C and N2O concentration of 10%. After a catalytic steady state was reached, no obvious decline was observed during a 15 h evaluation period.
      PubDate: 2017-05-04
      DOI: 10.3390/catal7050137
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 138: Cobalt-iron Oxide, Alloy and Nitride:
           Synthesis, Characterization and Application in Catalytic Peroxymonosulfate
           Activation for Orange II Degradation

    • Authors: Kaixin Zhu, Changzi Jin, Zoltán Klencsár, Ayyakannu Ganeshraja, Junhu Wang
      First page: 138
      Abstract: In meeting the need for environmental remediation in wastewater treatment and the development of popular sulfate-radical-based advanced oxidation processes (SR-AOPs), a series of Co/Fe-based catalysts with confirmed phase structure were prepared through extended soft chemical solution processes followed by atmosphere-dependent calcination. Powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and 57Fe Mössbauer spectroscopy were employed to characterize the composition, morphology, crystal structure and chemical state of the prepared catalysts. It was shown that calcination in air, nitrogen and ammonia atmospheres generated Co-Fe catalysts with cobalt ferrite (CoFe2O4), Co-Fe alloy and Co-Fe nitride as dominant phases, respectively. The prepared Co/Fe-based catalysts were demonstrated to be highly efficient in activating peroxymonosulfate (PMS) for organic Orange II degradation. The activation efficiency of the different catalysts was found to increase in the order CoFe2O4 < Co-Fe nitride < Co-Fe alloy. Sulfate radical was found to be the primary active intermediate species contributing to the dye degradation for all the participating catalysts. Furthermore, a possible reaction mechanism was proposed for each of the studied catalysts. This study achieves progress in efficient cobalt-iron catalysts using in the field of SR-AOPs, with potential applications in environment remediation.
      PubDate: 2017-05-04
      DOI: 10.3390/catal7050138
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 139: Tailoring the Oxygen Evolution Activity and
           Stability Using Defect Chemistry

    • Authors: Julius Scholz, Marcel Risch, Garlef Wartner, Christoph Luderer, Vladimir Roddatis, Christian Jooss
      First page: 139
      Abstract: Improving the activity of catalysts for the oxygen evolution reaction (OER) requires a detailed understanding of the surface chemistry and structure to deduce structure-function relationships (descriptors) for fundamental insight. We chose epitaxial (100)-oriented La0.6Sr0.4Mn1−δO3 (LSMO) thin films as a model system with high electrochemical activity comparable to (110)-oriented IrO2 to investigate the effect of Mn off-stoichiometry on both catalytic activity and stability. Extensive structural characterization was performed by microscopic and spectroscopic methods before and after electrochemical characterization using rotating ring-disk studies. Stoichiometric LSMO had the highest activity, while both Mn deficiency and excess reduced the catalytic activity. Furthermore, all samples preserved the crystal structure up to the very surface. Mn excess improved the long-term activity, and we hypothesize that excess Mn stabilizes the surface chemistry during catalysis. Our data show that the defect chemistry should be considered when designing catalysts with enhanced activity and rugged stability.
      PubDate: 2017-05-05
      DOI: 10.3390/catal7050139
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 140: Exploring Promising Catalysts for Chemical
           Hydrogen Storage in Ammonia Borane: A Density Functional Theory Study

    • Authors: Sateesh Bandaru, Niall English, Andrew Phillips, J. MacElroy
      First page: 140
      Abstract: Density functional theory (DFT) has been applied to study potential ammonia borane (AB) dehydrogenation pathways via new bifunctional ruthenium-based catalysts, alongside their computationally-designed iron-based counterparts (i.e., four catalysts), using the wB97XD (dispersion-included) functional. The efficiency of each catalyst was under scrutiny based on the addition of ammonia borane, with a focus on the associated activation-energy barriers, whilst hydrogen release from the catalyst was also studied in detail. Here, natural-population analysis charges were key quantities of interest. It was found that the iron-based catalysts display more promising dehydrogenation energy barriers vis-
      PubDate: 2017-05-05
      DOI: 10.3390/catal7050140
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 141: Post Synthesis of Aluminum Modified
           Mesoporous TUD-1 Materials and Their Application for FCC Diesel
           Hydrodesulfurization Catalysts

    • Authors: Zesheng Xia, Jianye Fu, Aijun Duan, Longnian Han, Huadong Wu, Zhen Zhao, Chunming Xu, Dong Wang, Bo Wang, Qian Meng
      First page: 141
      Abstract: Post-synthesis methods are a promising technology and have received much attention. In this paper, a series of post-synthesis aluminum modified TUD-1 (PAT) materials with different Al contents were successfully prepared by using aluminum isopropoxide to be Al sources, then the as-synthesized materials were adopted as support additives mixed with commercial γ-Al2O3 to prepare hydrodesulfurization (HDS) catalysts for FCC diesel. The supports and catalysts were analyzed using N2 adsorption-desorption, XRD, SEM, Py-IR, ICP, 27Al MAS NMR, UV-vis, H2-TPR and HRTEM techniques. The results of Py-IR and 27Al MAS NMR indicated that the addition of Al species could bring Lewis (L) and Brönsted (B) sites into Si-TUD-1, and that the material of PAT-3 had the highest total acidity sites and Brönsted acid sites among the series PAT composites. The HRTEM technique showed that, compared to the traditional catalyst NiMo/γ-Al2O3, the sulfided catalyst NiMo/APAT-3 had a relatively short length (3.2 nm) and suitable stacking number (2.5) of MoS2 slabs. The HDS efficiencies of all the catalysts were tested in a fixed bed micro-reactor with FCC diesel as feedstock. The catalytic results confirmed that the catalyst NiMo/APAT-3 possessed the highest HDS efficiency (97.0%), due to synergistic effects of advantageous properties such as higher acidity, moderate MSI, and relatively short length of the MoS2 slabs.
      PubDate: 2017-05-07
      DOI: 10.3390/catal7050141
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 142: Are Directed Evolution Approaches Efficient
           in Exploring Nature’s Potential to Stabilize a Lipase in Organic
           Cosolvents?

    • Authors: Ulrich Markel, Leilei Zhu, Victorine Frauenkron-Machedjou, Jing Zhao, Marco Bocola, Mehdi Davari, Karl-Erich Jaeger, Ulrich Schwaneberg
      First page: 142
      Abstract: Despite the significant advances in the field of protein engineering, general design principles to improve organic cosolvent resistance of enzymes still remain undiscovered. Previous studies drew conclusions to engineer enzymes for their use in water-miscible organic solvents based on few amino acid substitutions. In this study, we conduct a comparison of a Bacillus subtilis lipase A (BSLA) library—covering the full natural diversity of single amino acid substitutions at all 181 positions of BSLA—with three state of the art random mutagenesis methods: error-prone PCR (epPCR) with low and high mutagenesis frequency (epPCR-low and high) as well as a transversion-enriched Sequence Saturation Mutagenesis (SeSaM-Tv P/P) method. Libraries were searched for amino acid substitutions that increase the enzyme’s resistance to the water-miscible organic cosolvents 1,4-dioxane (DOX), 2,2,2-trifluoroethanol (TFE), and dimethyl sulfoxide (DMSO). Our analysis revealed that 5%–11% of all possible single substitutions (BSLA site-saturation mutagenesis (SSM) library) contribute to improved cosolvent resistance. However, only a fraction of these substitutions (7%–12%) could be detected in the three random mutagenesis libraries. To our knowledge, this is the first study that quantifies the capability of these diversity generation methods generally employed in directed evolution campaigns and compares them to the entire natural diversity with a single substitution. Additionally, the investigation of the BSLA SSM library revealed only few common beneficial substitutions for all three cosolvents as well as the importance of introducing surface charges for organic cosolvent resistance—most likely due to a stronger attraction of water molecules.
      PubDate: 2017-05-07
      DOI: 10.3390/catal7050142
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 143: Preparation of Salen–Metal Complexes
           (Metal = Co or Ni) Intercalated ZnCr-LDHs and Their Photocatalytic
           Degradation of Rhodamine B

    • Authors: Yue Meng, Wei Luo, Shengjie Xia, Zheming Ni
      First page: 143
      Abstract: Salen–metal complexes (SalenM) were successfully intercalated into ZnCr layered double hydroxides (LDHs) through coprecipitation method, then a series of novel organic–inorganic hybrid materials were obtained. The structure and properties of the materials were thoroughly characterized by inductively-coupled plasma atomic emission spectrometry (ICP-AES), powder X-ray diffraction (XRD), Fourier transform infrared spectrometry (FTIR), scanning electron microscopy (SEM), and ultraviolet visible diffuse reflectance spectroscopy (UV-Vis DRS). Meanwhile, with Rhodamine B (RhB) as a target contaminant, the photocatalytic activities of SalenM-intercalated ZnCr-LDHs were investigated and compared with the traditional LDHs (ZnCr-LDHs, ZnCoCr-LDHs, and ZnNiCr-LDHs). Furthermore, the effect of the intercalation amount of SalenM (M = Co or Ni) on the photocatalytic activity was studied. The results showed that when the molar ratio of SalenM to Cr was 0.75, SalenM-intercalated ZnCr-LDHs exhibited significantly higher photocatalytic activities than the traditional LDHs. The degradation rates of RhB reached about 90%, and all of them had good recycling rates. In addition, the kinetics of photocatalytic process and the mechanism of photocatalysis are discussed.
      PubDate: 2017-05-07
      DOI: 10.3390/catal7050143
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 144: Catalysts Promoted with Niobium Oxide for
           Air Pollution Abatement

    • Authors: Wendi Xiang, Xiaochen Han, Jennifer Astorsdotter, Robert Farrauto
      First page: 144
      Abstract: Pt-containing catalysts are currently used commercially to catalyze the conversion of carbon monoxide (CO) and hydrocarbon (HC) pollutants from stationary chemical and petroleum plants. It is well known that Pt-containing catalysts are expensive and have limited availability. The goal of this research is to find alternative and less expensive catalysts to replace Pt for these applications. This study found that niobium oxide (Nb2O5), as a carrier or support for certain transition metal oxides, promotes oxidation activity while maintaining stability, making them candidates as alternatives to Pt. The present work reports that the orthorhombic structure of niobium oxide (formed at 800 °C in air) promotes Co3O4 toward the oxidation of both CO and propane, which are common pollutants in volatile organic compound (VOC) applications. This was a surprising result since this structure of Nb2O5 has a very low surface area (about 2 m2/g) relative to the more traditional Al2O3 support, with a surface area of 150 m2/g. The results reported demonstrate that 1% Co3O4/Nb2O5 has comparable fresh and aged catalytic activity to 1% Pt/γ-Al2O3 and 1% Pt/Nb2O5. Furthermore, 6% Co3O4/Nb2O5 outperforms 1% Pt/Al2O3 in both catalytic activity and thermal stability. These results suggest a strong interaction between niobium oxide and the active component—cobalt oxide—likely by inducing an oxygen defect structure with oxygen vacancies leading to enhanced activity toward the oxidation of CO and propane.
      PubDate: 2017-05-08
      DOI: 10.3390/catal7050144
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 145: Hydrogenation of Phenol over Pt/CNTs: The
           Effects of Pt Loading and Reaction Solvents

    • Authors: Feng Li, Bo Cao, Wenxi Zhu, Hua Song, Keliang Wang, Cuiqin Li
      First page: 145
      Abstract: Carbon nanotubes (CNTs)-supported Pt nanoparticles were prepared with selective deposition of Pt nanoparticles inside and outside CNTs (Pt–in/CNTs and Pt–out/CNTs). The effects of Pt loading and reaction solvents on phenol hydrogenation were investigated. The Pt nanoparticles in Pt–in/CNTs versus Pt–out/CNTs are smaller and better dispersed. The catalytic activity and reuse stability toward phenol hydrogenation both improved markedly. The dichloromethane–water mixture as the reaction solvent, compared with either pure medium, decreased the catalytic activity toward phenol hydrogenation and selectivity of cyclohexanone over Pt–in/CNTs, but significantly improved the catalytic activity toward phenol hydrogenation and selectivity of cyclohexanone over Pt–out/CNTs.
      PubDate: 2017-05-08
      DOI: 10.3390/catal7050145
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 146: Palladium-Catalyzed Suzuki–Miyaura
           Cross-Coupling in Continuous Flow

    • Authors: Christophe Len, Sophie Bruniaux, Frederic Delbecq, Virinder Parmar
      First page: 146
      Abstract: Carbon–carbon cross-coupling reactions are among the most important processes in organic chemistry and Suzuki–Miyaura reactions are the most widely used protocols. For a decade, green chemistry and particularly catalysis and continuous flow, have shown immense potential in achieving the goals of “greener synthesis”. To date, it seems difficult to conceive the chemistry of the 21st century without the industrialization of continuous flow process in the area of pharmaceuticals, drugs, agrochemicals, polymers, etc. A large variety of palladium Suzuki–Miyaura cross-coupling reactions have been developed using a continuous flow sequence for preparing the desired biaryl derivatives. Our objective is to focus this review on the continuous flow Suzuki–Miyaura cross-coupling using homogeneous and heterogeneous catalysts.
      PubDate: 2017-05-09
      DOI: 10.3390/catal7050146
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 147: Spongin-Based Scaffolds from Hippospongia
           communis Demosponge as an Effective Support for Lipase Immobilization

    • Authors: Jakub Zdarta, Małgorzata Norman, Wojciech Smułek, Dariusz Moszyński, Ewa Kaczorek, Allison Stelling, Hermann Ehrlich, Teofil Jesionowski
      First page: 147
      Abstract: The main purpose of the study was to achieve effective immobilization of lipase B from Candida antarctica (CALB) onto 3D spongin-based scaffolds from Hippospongia communis marine demosponge for rapeseed oil transesterification. Successful immobilization onto the marine sponge skeleton was confirmed for the first time. Lipase B-containing biocatalytic system exhibited the highest catalytic activity retention (89%) after 60 min of immobilization at pH 7 and temperature of 4 °C. Immobilization was found to improve the thermal and chemical stability compared to free lipase, and retain over 80% of its initial catalytic activity over a wide range of temperature (30–60 °C) and pH (6–9). Additionally, immobilized lipase has good storage stability and retains over 70% of its initial activity even after catalyzing of 25 reaction cycles. The obtained product was used in a transesterification reaction of rapeseed oil with methanol and proved to be an efficient biocatalyst for biofuel production. The highest conversion value and fatty acids methyl esters (FAME) concentration were observed after a process conducted at 40 °C and pH 10. The possible mechanism of interaction between the enzyme and the spongin-based support is proposed and discussed.
      PubDate: 2017-05-10
      DOI: 10.3390/catal7050147
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 148: Methanol Steam Reforming: Na Doping of
           Pt/YSZ Provides Fine Tuning of Selectivity

    • Authors: Michela Martinelli, Gary Jacobs, Uschi Graham, Burtron Davis
      First page: 148
      Abstract: In this work, we found that sodium doping can be used to improve CO2 selectivity for supported Pt catalyst during methanol steam reforming. These materials are usually very active in the low temperature range; however, they are characterized by high selectivity of CO, which is a poison in downstream polymer electrolyte membrane fuel cells (PEM-FC) application. With Na doping, we found that CO2 selectivity was higher than 90% when 2.5 wt.% of sodium was added to Pt/YSZ. We have speculated that the different product distribution is due to a different reaction pathway being opened for CH3OH decomposition. Methanol decarbonylation was favored when Na was absent or low, while a formate decarboxylation pathway was favored when Na content reached 2.5 wt.%. The proposal is rooted in the observed weakening of the C-H bond of formate, as demonstrated in in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and kinetic isotope effect (KIE) experiments for the water-gas shift reaction conducted at low temperature. When adsorbed methoxy, produced when methanol is dissociatively adsorbed, was converted in the presence of H2O in DRIFTS spectroscopy, formate species were prevalent for a 2% Pt–2.5% Na/YSZ catalyst, while only a minor contribution was observed for 2% Pt/YSZ. Moreover, the formate produced on Na-doped Pt/YSZ exhibited ν(CH) stretching bands at low wavenumber, consistent with C–H bond weakening, thus favoring dehydrogenation (and decarboxylation). It is proposed that when Na is present, formate is likely an intermediate, and because its dehydrogenation is favored, selectivity can be fine-tuned between decarbonylation and decarboxylation based on Na dopant level.
      PubDate: 2017-05-10
      DOI: 10.3390/catal7050148
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 149: Factors Controlling the Redox Activity of
           

    • Authors: Chunzhen Yang, Alexis Grimaud
      First page: 149
      Abstract: Triggering the redox reaction of oxygens has become essential for the development of (electro) catalytic properties of transition metal oxides, especially for perovskite materials that have been envisaged for a variety of applications such as the oxygen evolution or reduction reactions (OER and ORR, respectively), CO or hydrocarbons oxidation, NO reduction and others. While the formation of ligand hole for perovskites is well-known for solid state physicists and/or chemists and has been widely studied for the understanding of important electronic properties such as superconductivity, insulator-metal transitions, magnetoresistance, ferroelectrics, redox properties etc., oxygen electrocatalysis in aqueous media at low temperature barely scratches the surface of the concept of oxygen ions oxidation. In this review, we briefly explain the electronic structure of perovskite materials and go through a few important parameters such as the ionization potential, Madelung potential, and charge transfer energy that govern the oxidation of oxygen ions. We then describe the surface reactivity that can be induced by the redox activity of the oxygen network and the formation of highly reactive surface oxygen species before describing their participation in catalytic reactions and providing mechanistic insights and strategies for designing new (electro) catalysts. Finally, we give a brief overview of the different techniques that can be employed to detect the formation of such transient oxygen species.
      PubDate: 2017-05-11
      DOI: 10.3390/catal7050149
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 150: Synthesis of SAPO-34 Molecular Sieves via
           Novel Intermittent Hydrothermal Treatment and Its Effect on the
           Crystallization and Product Properties

    • Authors: Zhihui Guo, Ping Miao, Weiping Zhu, Lei Guo, Fei Li, Yunpeng Xue, Qi Yin, Ruixue Yuan, Lianbin Xu
      First page: 150
      Abstract: Intermittent hydrothermal treatment was introduced into the synthesis of SAPO-34 molecular sieves to control the nucleation and the growth in the crystallization. The effect of the crystallization time, the order of long-time and short-time crystallization in two-stage crystallization, and frequency in multi-stage crystallization on synthesis, physicochemical properties and catalytic performance for conversion of methanol to light olefins (MTO) has been studied. The results show that pure SAPO-34 can be obtained with increasing crystallization time. The interruption of the initial crystallization is more beneficial for improving the Si distribution and the MTO catalytic performance of SAPO-34 molecular sieves. The sample obtained by repeatedly alternating heating and cooling during crystallization shows smaller particle size, higher acidity, longer lifetimes and higher yields of ethylene than that obtained by the conventional continuous crystallization at high temperature.
      PubDate: 2017-05-11
      DOI: 10.3390/catal7050150
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 151: Effect of Citric Acid on MoO3/Al2O3
           Catalysts for Sulfur-Resistant Methanation

    • Authors: Dajun Meng, Baowei Wang, Wenxia Yu, Weihan Wang, Zhenhua Li, Xinbin Ma
      First page: 151
      Abstract: A series of MoO3/Al2O3 catalysts with different amounts (molar ratio of CA/Mo = 0, 1, 1.5, and 2) of citric acid (CA) prepared by simultaneous impregnation were evaluated for sulfur-resistant methanation. Based on the evaluation results, catalytic activity increased accompanied with the rise of citric acid amount. Combine with the analysis of N2-physisorption, XRD, H2-TPR, XPS, and TEM, the catalyst saturated loading capacity improved, resulting in increasing dispersion of Mo species on Al2O3 surface clearly. According to H2-TPR result, the Mo oxide precursors can be more easily sulfureted when citric acid is added. Moreover, based on the Raman analysis, increasingly tetrahedrally coordinated Mo6+ species with high methanation performance are generated after citric acid treatment. These factors probably together accelerate MoO3/Al2O3 catalytic activity growth for methanation.
      PubDate: 2017-05-12
      DOI: 10.3390/catal7050151
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 152: Methanation of CO2 on Ni/Al2O3 in a
           Structured Fixed-Bed Reactor—A Scale-Up Study

    • Authors: Daniel Türks, Hesham Mena, Udo Armbruster, Andreas Martin
      First page: 152
      Abstract: Due to the ongoing change of energy supply, the availability of a reliable high-capacity storage technology becomes increasingly important. While conventional large-scale facilities are either limited in capacity respective supply time or their extension potential is little (e.g., pumped storage power stations), decentralized units could contribute to energy transition. The concepts of PtX (power-to-X) storage technologies and in particular PtG (power-to-gas) aim at fixation of electric power in chemical compounds. CO2 hydrogenation (methanation) is the foundation of the PtG idea as H2 (via electrolysis) and CO2 are easily accessible. Methane produced in this way, often called substitute natural gas (SNG), is a promising solution since it can be stored in the existing gas grid, tanks or underground cavern storages. Methanation is characterized by a strong exothermic heat of reaction which has to be handled safely. This work aims at getting rid of extreme temperature hot-spots in a tube reactor by configuring the catalyst bed structure. Proof of concept studies began with a small tube reactor (V = 12.5 cm3) with a commercial 18 wt % Ni/Al2O3 catalyst. Later, a double-jacket tube reactor was built (V = 452 cm3), reaching a production rate of 50 L/h SNG. The proposed approach not only improves the heat management and process safety, but also increases the specific productivity and stability of the catalyst remarkably.
      PubDate: 2017-05-15
      DOI: 10.3390/catal7050152
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 153: Structure-Dependent Photocatalytic
           Performance of BiOBrxI1−x Nanoplate Solid Solutions

    • Authors: Huan-Yan Xu, Xu Han, Qu Tan, Xiu-Lan He, Shu-Yan Qi
      First page: 153
      Abstract: BiOXxY1−x (X, Y = Cl, Br, and I) solid solutions have been regarded as promising photocatalysts attributed to their unique layered structure, tunable band structure, and chemical and optical stability. In this study, BiOBrxI1−x nanoplate solid solutions with a high exposure of {001} crystal facets were prepared by a facile alcoholysis method at room temperature and atmospheric pressure. X-ray diffraction (XRD) peaks exhibited a slight shift to lower diffraction angle with the increase of I content in BiOBrxI1−x samples, which resulted in a gradual increase in their cell parameters. Field emission scanning electron microscopy (FESEM) and transmission electron microscope (TEM) images revealed that BiOBrxI1−x samples exhibited 2D plate-like structure with the in-plane wrinkles. The regular changes in optical absorption threshold and Eg value seen in UV-vis diffuse reflectance spectra (UV-vis DRS) indicated that the optical absorption property and band structure could be modulated by the formation of BiOBrxI1−x solid solutions. The photocatalytic degradation of active dye Rhodamine B (RhB) over BiOBrxI1−x solid solutions showed that BiOBr0.75I0.25 had the best photocatalytic activity. The RhB photodegradation processes followed a pseudo-first-order kinetic model. The synergistic effect of structural factors (including amount of exposed {001} facets, interlayer spacing of (001) plane, and energy-level position of the valence band) determined the photocatalytic performance of BiOBrxI1−x solid solutions.
      PubDate: 2017-05-13
      DOI: 10.3390/catal7050153
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 154: Perovskite Electrocatalysts for the Oxygen
           Reduction Reaction in Alkaline Media

    • Authors: Marcel Risch
      First page: 154
      Abstract: Oxygen reduction is considered a key reaction for electrochemical energy conversion but slow kinetics hamper application in fuel cells and metal-air batteries. In this review, the prospect of perovskite oxides for the oxygen reduction reaction (ORR) in alkaline media is reviewed with respect to fundamental insight into activity and possible mechanisms. For gaining these insights, special emphasis is placed on highly crystalline perovskite films that have only recently become available for electrochemical interrogation. The prospects for applications are evaluated based on recent progress in the synthesis of perovskite nanoparticles. The review concludes with the current understanding of oxygen reduction on perovskite oxides and a perspective on opportunities for future fundamental and applied research.
      PubDate: 2017-05-13
      DOI: 10.3390/catal7050154
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 155: Catalytic Performance of MgO-Supported Co
           Catalyst for the Liquid Phase Oxidation of Cyclohexane with Molecular
           Oxygen

    • Authors: Mingzhou Wu, Yu Fu, Wangcheng Zhan, Yanglong Guo, Yun Guo, Yunsong Wang, Guanzhong Lu
      First page: 155
      Abstract: A highly-efficient and stable MgO-supported Co (Co/MgO) catalyst was developed for the oxidation of cyclohexane with oxygen. The effects of the Co loading and support on the catalytic activity of the supported Co3O4 catalyst were investigated. The results show that the Co supported on MgO presented excellent activity and stability. When the Co/MgO catalyst with the Co content of 0.2 wt% (0.2%Co/MgO) was used, 12.5% cyclohexane conversion and 74.7% selectivity to cyclohexanone and cyclohexanol (KA oil) were achieved under the reaction conditions of 0.5 MPa O2 and 140 °C for 4 h. After being repeatedly used 10 times, its catalytic activity was hardly changed. Further research showed that the high catalytic performance of the 0.2%Co/MgO catalyst is attributed to its high oxygen-absorbing ability and the high ratio between the amount of weak and medium base sites with the help of the synergistic interaction between Co and MgO.
      PubDate: 2017-05-13
      DOI: 10.3390/catal7050155
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 156: Effective Electron Transfer Pathway of the
           Ternary TiO2/RGO/Ag Nanocomposite with Enhanced Photocatalytic Activity
           under Visible Light

    • Authors: Hongwei Tian, Chenxing Wan, Xin Xue, Xiaoying Hu, Xiaoyi Wang
      First page: 156
      Abstract: Mesoporous TiO2/reduced graphene oxide/Ag (TiO2/RGO/Ag) ternary nanocomposite with an effective electron transfer pathway is obtained by an electrostatic self-assembly method and photo-assisted treatment. Compared with bare mesoporous TiO2 (MT) and mesoporous TiO2/RGO (MTG), the ternary mesoporous TiO2/RGO/Ag (MTGA) nanocomposite exhibited superior photocatalytic performance for the degradation of methylene blue (MB) under visible light, and the degradation rate reached 0.017 min−1, which was 3.4-times higher than that of MTG. What is more, the degradation rate of MTGA nanocomposite after three cycle times is 91.2%, and the composition is unchanged. In addition, we found that the OH•, h+ and especially O2•− contribute to the high photocatalytic activity of MTGA for MB degradation. It is proposed that Ag nanoparticles can form the local surface plasmon resonance (LSPR) to absorb the visible light and distract the electrons into MT, and RGO can accept the electrons from MT to accelerate the separation efficiency of photogenerated carriers. The establishment of MTGA ternary nanocomposite makes the three components act synergistically to enhance the photocatalytic performance.
      PubDate: 2017-05-15
      DOI: 10.3390/catal7050156
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 157: Development of Active and Stable Low Nickel
           Content Catalysts for Dry Reforming of Methane

    • Authors: Quan Ha, Udo Armbruster, Hanan Atia, Matthias Schneider, Henrik Lund, Giovanni Agostini, Jörg Radnik, Huyen Vuong, Andreas Martin
      First page: 157
      Abstract: Methane dry reforming (DRM) was investigated over highly active Ni catalysts with low metal content (2.5 wt %) supported on Mg-Al mixed oxide. The aim was to minimize carbon deposition and metal sites agglomeration on the working catalyst which are known to cause catalyst deactivation. The solids were characterized using N2 adsorption, X-ray diffraction, temperature-programmed reduction, X-ray photoelectron spectroscopy, and UV-Vis diffuse reflectance spectroscopy. The results showed that MgO-Al2O3 solid solution phases are obtained when calcining Mg-Al hydrotalcite precursor in the temperature range of 550–800 °C. Such phases contribute to the high activity of catalysts with low Ni content even at low temperature (500 °C). Modifying the catalyst preparation with citric acid significantly slows the coking rate and reduces the size of large octahedrally coordinated NiO-like domains, which may easily agglomerate on the surface during DRM. The most effective Ni catalyst shows a stable DRM course over 60 h at high weight hourly space velocity with very low coke deposition. This is a promising result for considering such catalyst systems for further development of an industrial DRM technology.
      PubDate: 2017-05-16
      DOI: 10.3390/catal7050157
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 158: Influence of Dissolved Ions on the Water
           Purification Performance of TiO2-Impregnated Porous Silica Tubes

    • Authors: Mio Hayashi, Tsuyoshi Ochiai, Shoko Tago, Hiromasa Tawarayama, Toshifumi Hosoya, Tsukaho Yahagi, Akira Fujishima
      First page: 158
      Abstract: TiO2-coated porous silica glass tubes containing macropores were fabricated and evaluated for their water-purification capacity using aqueous solutions of methylene blue. From the results of photocatalytic degradation tests at different initial methylene blue concentrations, the equilibrium adsorption constant (K) was determined to be 4.6 × 10−2 L µmol−1, and the Langmuir-Hinshelwood rate constant (kLH) was calculated as 2.6 µM min−1. To determine the influence of ions on the efficiency of methylene blue degradation, we examined both Milli-Q water (soft water) and Contrex water (hard water) as solvents, and confirmed the reduced purification for the Contrex solution. It was, therefore, considered that the presence of inorganic salts decreased the photocatalytic efficiency. Furthermore, variations in the methylene blue decomposition ability were observed between anion-free and cation-free Contrex. Finally, we concluded that the efficiency of photocatalytic decomposition of TiO2 was influenced by multiple parameters, including the presence of anions and cations, as well as the solution pH.
      PubDate: 2017-05-16
      DOI: 10.3390/catal7050158
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 159: Process Simulation for the Design and Scale
           Up of Heterogeneous Catalytic Process: Kinetic Modelling Issues

    • Authors: Antonio Tripodi, Matteo Compagnoni, Rocco Martinazzo, Gianguido Ramis, Ilenia Rossetti
      First page: 159
      Abstract: Process simulation represents an important tool for plant design and optimization, either applied to well established or to newly developed processes. Suitable thermodynamic packages should be selected in order to properly describe the behavior of reactors and unit operations and to precisely define phase equilibria. Moreover, a detailed and representative kinetic scheme should be available to predict correctly the dependence of the process on its main variables. This review points out some models and methods for kinetic analysis specifically applied to the simulation of catalytic processes, as a basis for process design and optimization. Attention is paid also to microkinetic modelling and to the methods based on first principles, to elucidate mechanisms and independently calculate thermodynamic and kinetic parameters. Different case studies support the discussion. At first, we have selected two basic examples from the industrial chemistry practice, e.g., ammonia and methanol synthesis, which may be described through a relatively simple reaction pathway and the relative available kinetic scheme. Then, a more complex reaction network is deeply discussed to define the conversion of bioethanol into syngas/hydrogen or into building blocks, such as ethylene. In this case, lumped kinetic schemes completely fail the description of process behavior. Thus, in this case, more detailed—e.g., microkinetic—schemes should be available to implement into the simulator. However, the correct definition of all the kinetic data when complex microkinetic mechanisms are used, often leads to unreliable, highly correlated parameters. In such cases, greater effort to independently estimate some relevant kinetic/thermodynamic data through Density Functional Theory (DFT)/ab initio methods may be helpful to improve process description.
      PubDate: 2017-05-18
      DOI: 10.3390/catal7050159
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 160: Catalytic Behaviour of CuO-CeO2 Systems
           Prepared by Different Synthetic Methodologies in the CO-PROX Reaction
           under CO2-H2O Feed Stream

    • Authors: Juan Cecilia, Ana Arango-Díaz, Jaasiel Marrero-Jerez, Pedro Núñez, Elisa Moretti, Loretta Storaro, Enrique Rodríguez-Castellón
      First page: 160
      Abstract: CuO-CeO2 catalysts, with 6 wt % of Cu, have been synthesised by different preparation methods (calcination of nitrate precursors, thermal urea-nitrate combustion, freeze-drying method, using polymethyl metacrylate PMMA microspheres as template and precipitation using NaOH or the decomposition of urea as precipitating agents). The obtained materials have been characterised by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, N2 adsorption-desorption at −196 °C, H2 thermoprogrammed reduction (H2-TPR) and X-ray photoelectron spectroscopy (XPS). The catalysts displayed high dispersion of copper oxide, obtaining CO conversion values of 90–100% at 115 °C in the CO preferential oxidation in excess of hydrogen (CO-PROX) and maintaining this activity even after 48 h of time on stream. The incorporation of CO2 and H2O in the feed stream (simulating a PROX unit) caused a decrease in the CO conversion, except for the catalyst synthesised using PMMA microspheres as a template which maintained a CO conversion of 95% at 115 °C. This catalyst exhibits an excellent catalytic performance, also under real operating conditions, thanks to many and concomitant factors, such as the very small CeO2 particle size (5.6 nm), the surface being rich in copper (atomic ratio Cu/Ce = 0.35) that is easily reducible, and the peculiar morphology and porosity of the material.
      PubDate: 2017-05-18
      DOI: 10.3390/catal7050160
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 161: Reactivity of Copper Electrodes towards
           Functional Groups and Small Molecules in the Context of CO2
           Electro-Reductions

    • Authors: Bernhard Schmid, Christian Reller, Sebastian Neubauer, Maximilian Fleischer, Romano Dorta, Guenter Schmid
      First page: 161
      Abstract: The direct electro-reduction of CO2 to functional molecules like ethene is a highly desirable variant of CO2 utilization. The formation of, for example, ethene from CO2 is a multistep electrochemical process going through various intermediates. As these intermediates are organic species, the CO2 reducing electro-catalyst has to be competent for a variety of organic functional group transformations to yield the final product. In this work, the activity of an in situ-grown nano-structured copper catalyst towards a variety of organic functional group conversions was studied. The model reagents were selected from the product spectrum of actual CO2 reduction reaction (CO2RR) experiments and from proposals in the literature. The CO2 bulk electrolysis benchmark was conducted at 170 mAcm−2 current density with up to 43% Faradaic Efficiency (FE) for ethene and 23% FE for ethanol simultaneously. To assure relevance for application-oriented conditions, the reactivity screening was conducted at elevated current densities and, thus, overpotentials. The found reactivity pattern was then also transferred to the CO reduction reaction (CORR) under benchmark conditions yielding additional insights. The results suggest that at high current density/high overpotential conditions, also other ethene formation pathways apart from acetaldehyde reduction such as CH2 dimerization are present. A new suggestion for a high current density mechanism will be presented, which is in agreement with the experimental observations and the found activity pattern of copper cathodes toward organic functional group conversion.
      PubDate: 2017-05-18
      DOI: 10.3390/catal7050161
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 162: Cellulose with a High Fractal Dimension Is
           Easily Hydrolysable under Acid Catalysis

    • Authors: Mariana Díaz, Magali Hernández, Ilich Ibarra, Ariel Guzmán, Victor Lara, Enrique Lima
      First page: 162
      Abstract: The adsorption of three diverse amino acids couples onto the surface of microcrystalline cellulose was studied. Characterisation of modified celluloses included changes in the polarity and in roughness. The amino acids partially break down the hydrogen bonding network of the cellulose structure, leading to more reactive cellulose residues that were easily hydrolysed to glucose in the presence of hydrochloric acid or tungstophosphoric acid catalysts. The conversion of cellulose and selectivity for glucose was highly dependent on the self-assembled amino acids adsorbed onto the cellulose and the catalyst.
      PubDate: 2017-05-19
      DOI: 10.3390/catal7050162
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 163: Catalytic Processes for Utilizing
           Carbohydrates Derived from Algal Biomass

    • Authors: Sho Yamaguchi, Ken Motokura, Kan Tanaka, Sousuke Imamura
      First page: 163
      Abstract: The high productivity of oil biosynthesized by microalgae has attracted increasing attention in recent years. Due to the application of such oils in jet fuels, the algal biosynthetic pathway toward oil components has been extensively researched. However, the utilization of the residue from algal cells after oil extraction has been overlooked. This residue is mainly composed of carbohydrates (starch), and so we herein describe the novel processes available for the production of useful chemicals from algal biomass-derived sugars. In particular, this review highlights our latest research in generating lactic acid and levulinic acid derivatives from polysaccharides and monosaccharides using homogeneous catalysts. Furthermore, based on previous reports, we discuss the potential of heterogeneous catalysts for application in such processes.
      PubDate: 2017-05-19
      DOI: 10.3390/catal7050163
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 164: Solar and Visible Light Illumination on
           Immobilized Nano Zinc Oxide for the Degradation and Mineralization of
           Orange G in Wastewater

    • Authors: Hung-Yee Shu, Ming-Chin Chang, Tien-Hsin Tseng
      First page: 164
      Abstract: An advanced oxidation process (AOP) utilizing immobilized zinc oxide (ZnO) photocatalyst was employed to decolorize and mineralize orange G (OG) azo dye in wastewater under solar and visible light irradiation. This AOP employed visible light and ZnO in a so-called Vis/ZnO process. Operating parameters, including ZnO dosage, initial OG concentration, pH, visible-light intensity, catalyst loaded area, and treatment volume were investigated to illustrate their influences on OG degradation and mineralization. From the results, neither visible light alone, nor the ZnO adsorption process could degrade or remove OG from wastewater. However, for the Vis/ZnO process, the higher ZnO dosage and visible light intensity are two major parameters to improve the OG degradation and total organic carbons (TOC) mineralization. The initial pH of 11 was the most effective pH condition on the OG degradation. The first-order rate constant is exponentially decreased from 0.025 to 0.0042 min−1 with the increase of the initial OG concentration and an empirical equation can be derived to estimate the first-order rate constant with a known initial OG concentration. In contrast, the first-order rate constant is linearly increased from 0.0027 to 0.0083 min−1 by increasing the visible light intensity. The results present that the Vis/ZnO process is an effective AOP for the degradation of OG in wastewater.
      PubDate: 2017-05-20
      DOI: 10.3390/catal7050164
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 165: Use of Metal Catalysts Bearing Schiff Base
           Macrocycles for the Ring Opening Polymerization (ROP) of Cyclic Esters

    • Authors: Carl Redshaw
      First page: 165
      Abstract: Schiff base macrocycles are emerging as useful scaffolds for binding two or more catalytic metals in close proximity. Such coordination chemistry allows for the evaluation of potentially beneficial catalytic cooperative effects. In the field of ring opening polymerization (ROP) of cyclic esters, only a handful of metal systems bound by Schiff base [2 + 2] type macrocycles have been studied. Nevertheless, results to date have, for certain metals, identified some interesting structure activity relationships, whilst for other systems results have revealed particular combinations of metals and macrocycles to be virtually inactive. This perspective review takes a look at two types of recently-reported Schiff base macrocycles that have been employed as pro-ligands in the metal-catalyzed ROP of cyclic esters, specifically ε-caprolactone and rac-lactide.
      PubDate: 2017-05-22
      DOI: 10.3390/catal7050165
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 166: Catalytic Decomposition of N2O over
           Cu–Zn/ZnAl2O4 Catalysts

    • Authors: Xiaoying Zheng, Runhu Zhang, Fang Bai, Chao Hua
      First page: 166
      Abstract: The catalytic decomposition of N2O was investigated over Cu-Zn/ZnAl2O4 catalysts in the temperature range of 400–650 °C Catalytic samples have been prepared by wet impregnation method. Prepared catalysts were characterized using several techniques like BET surface area, X-ray diffraction (XRD), and Scanning electron microscopy (SEM). The Cu-Zn/ZnAl2O4 showed higher catalytic performance along with long term stability during N2O decomposition. The Cu-Zn/ZnAl2O4 catalysts yielded 100% N2O conversion at 650 °C. The Cu-Zn/ZnAl2O4 catalysts are promising for decrease this strong greenhouse gas in the chemical industry.
      PubDate: 2017-05-22
      DOI: 10.3390/catal7050166
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 122: Promotive Effect of Sn2+ on Cu0/Cu+ Ratio
           and Stability Evolution of Cu/SiO2 Catalyst in the Hydrogenation of
           Dimethyl Oxalate

    • Authors: Chuancai Zhang, Denghao Wang, Bin Dai
      First page: 122
      Abstract: The influence of Sn2+doping on the structure and performance of silica supported copper catalyst was systematically investigated and characterised. Catalytic evaluation showed that the suitable content of Sn2+ introduced into a Cu/SiO2 catalyst evidently improved the catalytic activity and stability of ethylene glycol synthesis from dimethyl oxalate. X-ray diffraction and X-ray auger electron spectroscopy indicated that the Cu0/Cu+ ratio gradually increased with increasing Sn2+ content, and an appropriate proportion of Cu0/Cu+ ratio played a very significant role in this reaction. Transmission electron microscopy revealed that the active copper particles in the Cu-xSn/SiO2 catalyst were smaller than those of the Cu/SiO2 catalyst. This result may be due to the introduction of Sn2+ species transformed into SnO2. Furthermore, SnO2 effectively segregated the active copper. These effects are beneficial in inhibiting the aggregation of copper in the catalysts, thereby improving the stability of the catalyst and prolonging the life span.
      PubDate: 2017-04-19
      DOI: 10.3390/catal7040122
      Issue No: Vol. 7, No. 4 (2017)
       
  • Catalysts, Vol. 7, Pages 123: A Simple and Efficient Process for Large
           Scale Glycerol Oligomerization by Microwave Irradiation

    • Authors: Rémi Nguyen, Nicolas Galy, Abhishek Singh, Florian Paulus, Daniel Stöbener, Cathleen Schlesener, Sunil Sharma, Rainer Haag, Christophe Len
      First page: 123
      Abstract: Herein, an optimized method for 100 g scale synthesis of glycerol oligomers using a microwave multimode source and the low priced K2CO3 as catalyst is reported. This method allows the complete conversion of glycerol to its oligomers in only 30 min, yielding molecular weights up to 1000 g mol−1. Furthermore, a simple iterative purification process, involving the precipitation of the crude product in acetone and methanol, affords a final product composed of larger oligomers with a narrow dispersity (D < 1.5).
      PubDate: 2017-04-19
      DOI: 10.3390/catal7040123
      Issue No: Vol. 7, No. 4 (2017)
       
  • Catalysts, Vol. 7, Pages 124: In Search of Governing Gas Flow Mechanism
           through Metal Solid Foams

    • Authors: Anna Gancarczyk, Marcin Piątek, Marzena Iwaniszyn, Przemysław Jodłowski, Joanna Łojewska, Jolanta Kowalska, Andrzej Kołodziej
      First page: 124
      Abstract: Solid foams have been intensely studied as promising structured catalytic internals. However, mechanisms governing flow and transport phenomena within the foam structures have not been properly addressed in the literature. The aim of this study was to consider such flow mechanisms based on our experimental results on flow resistance. Two mechanisms were considered: developing laminar flow in a short capillary channel (flow-through model), and flow around an immersed solid body, either a cylinder or sphere (flow-around model). Flow resistance experiments were performed on three aluminum foams of 10, 20, and 40 PPI (pores per inch), using a 57 mm ID test column filled with the foams studied. The foam morphology was examined using microtomography and optical microscopy to derive the geometric parameters applied in the model equations. The flow-through model provided an accuracy of 25% for the experiments. The model channel diameter was the foam cell diameter, and the channel length was the strut thickness. The accuracy of the flow-around model was only slightly worse (35%). It was difficult to establish the geometry of the immersed solid body (sphere or cylinder) because experiment characteristics tended to change from sphere to cylinder with increasing PPI value.
      PubDate: 2017-04-21
      DOI: 10.3390/catal7040124
      Issue No: Vol. 7, No. 4 (2017)
       
  • Catalysts, Vol. 7, Pages 125: Preparation of Rh/Ni Bimetallic
           Nanoparticles and Their Catalytic Activities for Hydrogen Generation from
           Hydrolysis of KBH4

    • Authors: Liqiong Wang, Liang Huang, Chengpeng Jiao, Zili Huang, Feng Liang, Simin Liu, Yuhua Wang, Haijun Zhang
      First page: 125
      Abstract: ISOBAM-104 protected Rh/Ni bimetallic nanoparticles (BNPs) of 3.1 nm in diameter were synthesized by a co-reduction method with a rapid injection of KBH4 solution. The catalytic activities of as-prepared BNPs for hydrogen generation from hydrolysis of a basic KBH4 solution were evaluated. Ultraviolet-visible spectrophotometry (UV-Vis), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM) were employed to characterize the structure, particle size, and chemical composition of the resultant BNPs. Catalytic activities for hydrolysis of KBH4 and catalytic kinetics of prepared BNPs were also investigated. It was shown that Rh/Ni BNPs displayed much higher catalytic activities than that of Rh or Ni monometallic nanoparticles (MNPs), and the prepared Rh10Ni90 BNPs possessed the highest catalytic activities with a value of 11580 mol-H2·h−1·mol-Rh−1. The high catalytic activities of Rh/Ni BNPs could be attributed to the electron transfer effect between Rh and Ni atoms, which was confirmed by a density functional theory (DFT) calculation. The apparent activation energy for hydrogen generation of the prepared Rh10Ni90 BNPs was about 47.2 ± 2.1 kJ/mol according to a kinetic study.
      PubDate: 2017-04-23
      DOI: 10.3390/catal7040125
      Issue No: Vol. 7, No. 4 (2017)
       
 
 
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