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Volume 7
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Catalysts, Volume 7, Issue 1 (January 2017) – 35 articles

Cover Story (view full-size image): Mimicking a leaf’s ability to convert solar energy into chemical energy in a very sophisticated photosynthesis process is the holy grail of photocatalysis. Very recently, scientists have been making huge and important progress in engineering and producing materials that can make the development of efficient artificial leaves a reality.
Photoelectrochemical water splitting is a form of artificial photosynthesis. It uses abundant and perpetual resources, such as water and the sun, to produce the solar fuels - H2 and O2. The bottleneck for this process is the water oxidation half-reaction, and BiVO4 is a very promising material to address this issue. View this paper.
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26 pages, 7729 KiB  
Review
The New Graphene Family Materials: Synthesis and Applications in Oxygen Reduction Reaction
by Xin Tong 1,2, Qiliang Wei 2, Xinxing Zhan 1, Gaixia Zhang 2 and Shuhui Sun 2,*
1 Key Lab for Functional Materials Chemistry of Guizhou Province, School of Chemistry and Material Science, Guizhou Normal University, Guiyang 550001, China
2 Institut National de la Recherche Scientifique (INRS), Énergie, Matériaux et Télécommunications, 650 Boulevard Lionel-Boulet, Varennes, QC J3X 1S2, Canada
Catalysts 2017, 7(1), 1; https://doi.org/10.3390/catal7010001 - 23 Dec 2016
Cited by 39 | Viewed by 11682
Abstract
Graphene family materials, including graphene quantum dots (GQDs), graphene nanoribbons (GNRs) and 3D graphene (3D-G), have attracted much research interest for the oxygen reduction reaction (ORR) in fuel cells and metal-air batteries, due to their unique structural characteristics, such as abundant activate sites, [...] Read more.
Graphene family materials, including graphene quantum dots (GQDs), graphene nanoribbons (GNRs) and 3D graphene (3D-G), have attracted much research interest for the oxygen reduction reaction (ORR) in fuel cells and metal-air batteries, due to their unique structural characteristics, such as abundant activate sites, edge effects and the interconnected network. In this review, we summarize recent developments in fabricating various new graphene family materials and their applications for use as ORR electrocatalysts. These new graphene family materials play an important role in improving the ORR performance, thus promoting the practical use in metal-air batteries and fuel cells. Full article
(This article belongs to the Special Issue Graphene-Based Materials for Energy Conversion)
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27 pages, 490 KiB  
Review
Strengths, Weaknesses, Opportunities and Threats: Computational Studies of Mn- and Fe-Catalyzed Epoxidations
by Filipe Teixeira * and M. Natália D. S. Cordeiro *
LAQV-REQUIMTE, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal
Catalysts 2017, 7(1), 2; https://doi.org/10.3390/catal7010002 - 23 Dec 2016
Cited by 12 | Viewed by 8767
Abstract
The importance of epoxides as synthetic intermediates in a number of highly added-value chemicals, as well as the search for novel and more sustainable chemical processes have brought considerable attention to the catalytic activity of manganese and iron complexes towards the epoxidation of [...] Read more.
The importance of epoxides as synthetic intermediates in a number of highly added-value chemicals, as well as the search for novel and more sustainable chemical processes have brought considerable attention to the catalytic activity of manganese and iron complexes towards the epoxidation of alkenes using non-toxic terminal oxidants. Particular attention has been given to Mn(salen) and Fe(porphyrin) catalysts. While the former attain remarkable enantioselectivity towards the epoxidation of cis-alkenes, the latter also serve as an important model for the behavior of cytochrome P450, thus allowing the exploration of complex biological processes. In this review, a systematic survey of the bibliographical data for the theoretical studies on Mn- and Fe-catalyzed epoxidations is presented. The most interesting patterns and trends are reported and finally analyzed using an evaluation framework similar to the SWOT (Strengths, Weaknesses, Opportunities and Threats) analysis performed in enterprise media, with the ultimate aim to provide an overview of current trends and areas for future exploration. Full article
(This article belongs to the Special Issue Computational Methods and Their Application in Catalysis)
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17 pages, 4710 KiB  
Article
Synthesis of Magnetic Carbon Supported Manganese Catalysts for Phenol Oxidation by Activation of Peroxymonosulfate
by Yuxian Wang 1,*, Yongbing Xie 2, Chunmao Chen 1, Xiaoguang Duan 3, Hongqi Sun 4 and Shaobin Wang 3
1 State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Beijing, 18 Fuxue Road, Beijing 102249, China
2 Beijing Engineering Research Center of Process Pollution Control, Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
3 Department of Chemical Engineering, Curtin University, GPO Box U1987, Perth 6845, Australia
4 School of Engineering, Edith Cowan University, 270 Joondalup Drive, Joondalup 6027, Australia
Catalysts 2017, 7(1), 3; https://doi.org/10.3390/catal7010003 - 26 Dec 2016
Cited by 13 | Viewed by 7132
Abstract
Magnetic core/shell nanospheres (MCS) were synthesized by a novel and facile one-step hydrothermal method. Supported manganese oxide nanoparticles (Fe3O4/C/Mn) were obtained from various methods (including redox, hydrothermal and impregnation) using MCS as the support material and potassium permanganate as [...] Read more.
Magnetic core/shell nanospheres (MCS) were synthesized by a novel and facile one-step hydrothermal method. Supported manganese oxide nanoparticles (Fe3O4/C/Mn) were obtained from various methods (including redox, hydrothermal and impregnation) using MCS as the support material and potassium permanganate as the precursor of manganese oxide. The Mn/MCS catalysts were characterized by a variety of characterization techniques and the catalytic performances of Fe3O4/C/Mn nanoparticles were tested in activation of peroxymonosulfate to produce reactive radicals for phenol degradation in aqueous solutions. It was found that Fe3O4/C/Mn catalysts can be well dispersed and easily separated from the aqueous solutions by an external magnetic field. Kinetic analysis showed that phenol degradation on Fe3O4/C/Mn catalysts follows the first order kinetics. The peroxymonosulfate activation mechanism by Fe3O4/C/Mn catalysts for phenol degradation was then discussed. Full article
(This article belongs to the Special Issue Heterogeneous Catalysis for Environmental Remediation)
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10 pages, 1806 KiB  
Article
Synthesis and Characterization of Highly Stabilized Polymer–Trypsin Conjugates with Autolysis Resistance
by Yasushi Sasai 1,*, Hiroshi Kanno 1, Naoki Doi 1, Yukinori Yamauchi 2, Masayuki Kuzuya 3 and Shin-ichi Kondo 1
1 Laboratory of Pharmaceutical Physical Chemistry, Department of Drug Delivery Technology and Sciences, Gifu Pharmaceutical University, 1-25-4, Daigaku-Nishi, Gifu 501-1196, Japan
2 Department of Pharmaceutical Physical Chemistry, College of Pharmaceutical Sciences, Matsuyama University, 4-2 Bunkyo-cho, Matsuyama, Ehime 790-8578, Japan
3 Faculty of Human Welfare, Chubu Gakuin University, 2-1 Kirigaoka, Sek-shi, Gifu 501-3993, Japan
Catalysts 2017, 7(1), 4; https://doi.org/10.3390/catal7010004 - 26 Dec 2016
Cited by 13 | Viewed by 7610
Abstract
Protein digestion by trypsin has been widely used in many industrial and research applications. However, extensive use of trypsin is limited because of the rapid decrease in enzymatic activity caused by autolysis at optimal pH and temperature. To improve the enzymatic performance of [...] Read more.
Protein digestion by trypsin has been widely used in many industrial and research applications. However, extensive use of trypsin is limited because of the rapid decrease in enzymatic activity caused by autolysis at optimal pH and temperature. To improve the enzymatic performance of trypsin, we synthesized highly stabilized polymer–trypsin conjugates using vinylmethylether-maleic acid copolymer (VEMAC) via multi-point attachment. The VEMAC modification significantly enhanced the thermal stability of trypsin, and the resulting conjugates showed a strong resistance to autolysis. VEMAC-modified trypsin (VEMAC-Tryp) showed maximum activity at 55 °C and at 1.4-fold higher levels than that of unmodified trypsin. Bovine serum albumin was effectively digested by VEMAC-Tryp, indicating that the modified trypsin can be used for digestion of high molecular weight substrates. VEMAC modification is a simple and cost-effective strategy to obtain fully active modified enzymes, and may be used to develop bioreactors. Full article
(This article belongs to the Special Issue Immobilized Enzymes: Strategies for Enzyme Stabilization)
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12 pages, 2543 KiB  
Article
Reaction Mechanisms of CO2 Reduction to Formaldehyde Catalyzed by Hourglass Ru, Fe, and Os Complexes: A Density Functional Theory Study
by Chunhua Dong 1,2,3, Mingsong Ji 1, Xinzheng Yang 1,*, Jiannian Yao 2 and Hui Chen 2,*
1 Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
2 Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
3 College of Chemistry, Chemical Engineering and Material, Handan Key Laboratory of Organic Small Molecule Materials, Handan University, Handan 056005, China
Catalysts 2017, 7(1), 5; https://doi.org/10.3390/catal7010005 - 27 Dec 2016
Cited by 20 | Viewed by 9139
Abstract
The reaction mechanisms for the reduction of carbon dioxide to formaldehyde catalyzed by bis(tricyclopentylphosphine) metal complexes, [RuH2(H2)(PCyp3)2] (1Ru), [FeH2(H2)(PCyp3)2] (1Fe) and [...] Read more.
The reaction mechanisms for the reduction of carbon dioxide to formaldehyde catalyzed by bis(tricyclopentylphosphine) metal complexes, [RuH2(H2)(PCyp3)2] (1Ru), [FeH2(H2)(PCyp3)2] (1Fe) and [OsH4(PCyp3)2] (1Os), were studied computationally by using the density functional theory (DFT). 1Ru is a recently reported highly efficient catalyst for this reaction. 1Fe and 1Os are two analogues of 1Ru with the Ru atom replaced by Fe and Os, respectively. The total free energy barriers of the reactions catalyzed by 1Ru, 1Fe and 1Os are 24.2, 24.0 and 29.0 kcal/mol, respectively. With a barrier close to the experimentally observed Ru complex, the newly proposed iron complex is a potential low-cost catalyst for the reduction of carbon dioxide to formaldehyde under mild conditions. The electronic structures of intermediates and transition states in these reactions were analyzed by using the natural bond orbital theory. Full article
(This article belongs to the Special Issue Ruthenium Catalysts)
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13 pages, 2512 KiB  
Article
Hydrothermal Stability of Ru/SiO2–C: A Promising Catalyst for Biomass Processing through Liquid-Phase Reactions
by Martín N. Gatti 1, Bárbara Lombardi 2, Delia Gazzoli 3, Gerardo F. Santori 1, Francisco Pompeo 1 and Nora N. Nichio 1,*
1 Centro de Investigación y Desarrollo en Ciencias Aplicadas (CINDECA) y Facultad de Ingeniería, Universidad Nacional de La Plata-Consejo Nacional de Investigaciones Científicas y Técnicas (UNLP-CONICET), 47 No. 257, 1900 La Plata, Argentina
2 Centro de Tecnología de Recursos Minerales y Cerámica (CETMIC), Comisión de Investigaciones Científicas-Consejo Nacional de Investigaciones Científicas y Técnicas (CIC-CONICET) La Plata, Universidad Nacional de La Plata (UNLP), Camino Centenario y 506, 1897 Gonnet, Argentina
3 Dipartimento di Chimica, Università di Roma “La Sapienza”, P.le A. Moro 5, 00185 Roma, Italy
Catalysts 2017, 7(1), 6; https://doi.org/10.3390/catal7010006 - 27 Dec 2016
Cited by 6 | Viewed by 6269
Abstract
In this work, structural and morphological properties of SiO2–C composite material to be used as support for catalysts in the conversion of biomass-derived oxygenated hydrocarbons, such as glycerol, were investigated in liquid water under various temperatures conditions. The results show that [...] Read more.
In this work, structural and morphological properties of SiO2–C composite material to be used as support for catalysts in the conversion of biomass-derived oxygenated hydrocarbons, such as glycerol, were investigated in liquid water under various temperatures conditions. The results show that this material does not lose surface area, and the hot liquid water does not generate changes in the structure. Neither change in relative concentrations of oxygen functional groups nor in Si/C ratio due to hydrothermal treatment was revealed by X-ray photoelectron spectroscopy (XPS) analysis. Raman analysis showed that the material is made of a disordered graphitic structure in an amorphous silica matrix, which remains stable after hydrothermal treatment. Results of the hydrogenolysis of glycerol using a Ru/SiO2–C catalyst indicate that the support gives more stability to the active phase than a Ru/SiO2 consisting of commercial silica. Full article
(This article belongs to the Special Issue Ruthenium Catalysts)
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11 pages, 7403 KiB  
Article
Dehydrogenative Oxidation of Alcohols Catalyzed by Highly Dispersed Ruthenium Incorporated Titanium Oxide
by Youngyong Kim 1, Seokhoon Ahn 2, Jun Yeon Hwang 2, Doo-Hyun Ko 3,* and Ki-Young Kwon 1,*
1 Department of Chemistry, Gyeongsang National University and RINS, Jinju 660-701, Korea
2 Institute of Advanced Composite Materials, Korea Institute of Science and Technology, Chudong-ro 92, Bongdong-eup, Wanju-gun, Jeonbuk 565-950, Korea
3 Department of Applied Chemistry, Kyung Hee University, 1 Seochun-Dong, Giheung-Gu, Yongin-Si, Gyeonggi-Do 446-701, Korea
Catalysts 2017, 7(1), 7; https://doi.org/10.3390/catal7010007 - 28 Dec 2016
Cited by 16 | Viewed by 6250
Abstract
Ruthenium incorporated titanium oxides (RuxTiO2) were prepared by a one-step hydrothermal method using Ti(SO4)2 and RuCl3 as the precursor of Ti and Ru, respectively. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscope (TEM), [...] Read more.
Ruthenium incorporated titanium oxides (RuxTiO2) were prepared by a one-step hydrothermal method using Ti(SO4)2 and RuCl3 as the precursor of Ti and Ru, respectively. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscope (TEM), Energy-dispersive X-ray spectroscopy (EDS) mapping, and BET were applied for the analyses of catalysts. Ruthenium atoms are well dispersed in the anatase phase of TiO2 and the crystallite size of RuxTiO2 (≈17 nm) is smaller than that of pure TiO2 (≈45 nm). In particular, we found that our homemade pure TiO2 exhibits a strong Lewis acid property. Therefore, the cooperation of ruthenium atoms playing a role in the hydride elimination and the Lewis acid site of TiO2 can efficiently transfer primary alcohols into corresponding aldehydes in an oxidant-free condition. Full article
(This article belongs to the Special Issue Ruthenium Catalysts)
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13 pages, 3311 KiB  
Article
In Situ FTIR Analysis of CO-Tolerance of a Pt-Fe Alloy with Stabilized Pt Skin Layers as a Hydrogen Anode Catalyst for Polymer Electrolyte Fuel Cells
by Yoshiyuki Ogihara 1, Hiroshi Yano 2, Takahiro Matsumoto 3, Donald A. Tryk 2, Akihiro Iiyama 2 and Hiroyuki Uchida 2,4,*
1 Special Doctoral Program for Green Energy Conversion Science and Technology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, 4 Takeda, Kofu 400-8510, Japan
2 Fuel Cell Nanomaterials Center, University of Yamanashi, 4 Takeda, Kofu 400-8510, Japan
3 Department of Applied Chemistry, Faculty of Engineering, University of Yamanashi, 4 Takeda, Kofu 400-8510, Japan
4 Clean Energy Research Center, University of Yamanashi, 4 Takeda, Kofu 400-8510, Japan
Catalysts 2017, 7(1), 8; https://doi.org/10.3390/catal7010008 - 29 Dec 2016
Cited by 14 | Viewed by 10211
Abstract
The CO-tolerance mechanism of a carbon-supported Pt-Fe alloy catalyst with two atomic layers of stabilized Pt-skin (Pt2AL–PtFe/C) was investigated, in comparison with commercial Pt2Ru3/C (c-Pt2Ru3/C), by in situ attenuated total reflection Fourier transform [...] Read more.
The CO-tolerance mechanism of a carbon-supported Pt-Fe alloy catalyst with two atomic layers of stabilized Pt-skin (Pt2AL–PtFe/C) was investigated, in comparison with commercial Pt2Ru3/C (c-Pt2Ru3/C), by in situ attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy in 0.1 M HClO4 solution at 60 °C. When 1% CO (H2-balance) was bubbled continuously in the solution, the hydrogen oxidation reaction (HOR) activities of both catalysts decreased severely because the active sites were blocked by COad, reaching the coverage θCO ≈ 0.99. The bands in the IR spectra observed on both catalysts were successfully assigned to linearly adsorbed CO (COL) and bridged CO (COB), both of which consisted of multiple components (COL or COB at terraces and step/edge sites). The Pt2AL–PtFe/C catalyst lost 99% of its initial mass activity (MA) for the HOR after 30 min, whereas about 10% of the initial MA was maintained on c-Pt2Ru3/C after 2 h, which can be ascribed to a suppression of linearly adsorbed CO at terrace sites (COL, terrace). In contrast, the HOR activities of both catalysts with pre-adsorbed CO recovered appreciably after bubbling with CO-free pure H2. We clarify, for the first time, that such a recovery of activity can be ascribed to an increased number of active sites by a transfer of COL, terrace to COL, step/edge, without removal of COad from the surface. The Pt2AL–PtFe/C catalyst showed a larger decrease in the band intensity of COL, terrace. A possible mechanism for the CO-tolerant HOR is also discussed. Full article
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34 pages, 990 KiB  
Review
The Protagonism of Biocatalysis in Green Chemistry and Its Environmental Benefits
by Viridiana Santana Ferreira-Leitão 1,2,*, Magali Christe Cammarota 3, Erika Cristina Gonçalves Aguieiras 1, Lívian Ribeiro Vasconcelos de Sá 1,2, Roberto Fernandez-Lafuente 4,* and Denise Maria Guimarães Freire 1,*
1 Department of Biochemistry, Federal University of Rio de Janeiro, Avenida Athos da Silveira Ramos, 149, Bloco A, Sala 549-1, Cidade Universitária, CEP 21941-909 Rio de Janeiro, Brazil
2 Laboratory of Biocatalysis, Ministry of Science and Technology, National Institute of Technology, Avenida Venezuela, 82, Sala 302, CEP 20081-312 Rio de Janeiro, Brazil
3 Department of Biochemical Engineering, Federal University of Rio de Janeiro, CEP 21941-909 Rio de Janeiro, Brazil
4 Departamento de Biocatálisis, Instituto de Catálisis-CSIC, Campus UAM-CSIC, C/Marie Curie 2, Cantoblanco, 28049 Madrid, Spain
Catalysts 2017, 7(1), 9; https://doi.org/10.3390/catal7010009 - 1 Jan 2017
Cited by 66 | Viewed by 11661
Abstract
The establishment of a bioeconomy era requires not only a change of production pattern, but also a deep modernization of the production processes through the implementation of novel methodologies in current industrial units, where waste materials and byproducts can be utilized as starting [...] Read more.
The establishment of a bioeconomy era requires not only a change of production pattern, but also a deep modernization of the production processes through the implementation of novel methodologies in current industrial units, where waste materials and byproducts can be utilized as starting materials in the production of commodities such as biofuels and other high added value chemicals. The utilization of renewable raw resources and residues from the agro-industries, and their exploitation through various uses and applications through technologies, particularly solid-state fermentation (SSF), are the main focus of this review. The advocacy for biocatalysis in green chemistry and the environmental benefits of bioproduction are very clear, although this kind of industrial process is still an exception and not the rule. Potential and industrial products, such as biocatalysts, animal feed, fermentation medium, biofuels (biodiesel, lignocelulose ethanol, CH4, and H2), pharmaceuticals and chemicals are dealt with in this paper. The focus is the utilization of renewable resources and the important role of enzymatic process to support a sustainable green chemical industry. Full article
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12 pages, 2414 KiB  
Article
N2O Direct Dissociation over MgxCeyCo1−x−yCo2O4 Composite Spinel Metal Oxide
by Ning Liu 1,2, Ping Chen 1, Yingxia Li 1 and Runduo Zhang 1,*
1 State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China
2 Changzhou Institute of Advanced Materials, Beijing University of Chemical Technology, Changzhou 213164, China
Catalysts 2017, 7(1), 10; https://doi.org/10.3390/catal7010010 - 1 Jan 2017
Cited by 7 | Viewed by 6073
Abstract
A series of Mg- and/or Ce-doped Co3O4 (MgxCo1−xCo2O4 CexCo1−xCo2O4, MgxCeyCo1−x−yCo2O4) [...] Read more.
A series of Mg- and/or Ce-doped Co3O4 (MgxCo1−xCo2O4 CexCo1−xCo2O4, MgxCeyCo1−x−yCo2O4) composite spinel metal-oxide catalyst was prepared by a coprecipitation method and evaluated for N2O direct decomposition. The activity measurement results suggest that Mg0.025Ce0.05Co0.925Co2O4 with a Mg/Ce mole ratio of 0.5 exhibited the highest N2O conversion activity, achieving 100% N2O conversion at T = 250 °C (35 vol % N2O balanced by He, gas hourly space velocity (GHSV) = 30,000 h−1). Characterizations using X-ray diffraction (XRD), Brunauer–Emmett–Teller method (BET), hydrogen temperature-programmed reduction (H2-TPR), and X-ray photoelectron spectroscopy (XPS) reveal that there were three main reasons for the excellent catalytic behavior of Mg0.025Ce0.05Co0.925Co2O4: (a) Mg and Ce co-doping could reduce the grain size of composite spinel metal oxide, which thereby significantly increased the BET specific surface area of Mg0.025Ce0.05Co0.925Co2O4 (111.2 g·m2 with respect to that of 32.5 g·m−2 for Co3O4); (b) Mg and Ce co-doping could improve the redox ability of Mg0.025Ce0.05Co0.925Co2O4, including reductions of Co3+ → Co2+ and Co2+ → Co0; and (c) Mg and Ce co-doping not only could improve the migration ability of surface atomic O, but also could increase the concentrations of surface atomic O. Full article
(This article belongs to the Special Issue Ceria-based Catalysts)
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13 pages, 13138 KiB  
Article
The Distribution and Strength of Brönsted Acid Sites on the Multi-Aluminum Model of FER Zeolite: A Theoretical Study
by Miao He, Jie Zhang *, Rui Liu, Xiuliang Sun and Biaohua Chen
State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China
Catalysts 2017, 7(1), 11; https://doi.org/10.3390/catal7010011 - 1 Jan 2017
Cited by 11 | Viewed by 8848
Abstract
One of the fundamental issues in catalysis is to identify the catalytic active site. Due to its prominent pore topology and acidity, ferrierite (FER) zeolite has attracted extensive interest in various catalytic reactions such as isomerization of butenes. However knowledge on the active [...] Read more.
One of the fundamental issues in catalysis is to identify the catalytic active site. Due to its prominent pore topology and acidity, ferrierite (FER) zeolite has attracted extensive interest in various catalytic reactions such as isomerization of butenes. However knowledge on the active Brönsted acid site is still absent. In the present study, we perform extensive density functional theory calculations to explore the distribution and strength of the Brönsted acid sites and their potential catalytic activity for the double-bond isomerization of 1-butene to 2-butene. We employ a two-layered ONIOM scheme (our Own N-layered Integrated molecular Orbital + molecular Mechanics) to describe the structure and energetic properties of FER zeolite. We find that the hydrogen bond could improve the stability of Brönsted acid sites effectively, and, as a result, Al4-O6-Si2 and Al4-O-(SiO)2-Al4 are the most stable sites for 1-Al substitution and 2-Al substitution, respectively. We further find that the Brönsted acid strength tends to decrease with the increase of Al contents and increase when the distance between the Al atoms is increased in 2-Al substitution. Finally it is demonstrated that the strength of acid sites determines the catalytic activity for the double bond isomerization of 1-butene to 2-butene. Full article
(This article belongs to the Special Issue Computational Methods and Their Application in Catalysis)
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21 pages, 2940 KiB  
Review
C-Homoscorpionate Oxidation Catalysts—Electrochemical and Catalytic Activity
by Luísa M. D. R. S. Martins 1,2
1 Chemical Engineering Department, Instituto Superior de Engenharia de Lisboa, Instituto Politécnico de Lisboa, R. Conselheiro Emídio Navarro, 1959-007 Lisboa, Portugal
2 Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049–001 Lisboa, Portugal
Catalysts 2017, 7(1), 12; https://doi.org/10.3390/catal7010012 - 1 Jan 2017
Cited by 34 | Viewed by 7675
Abstract
A survey of the electrochemical properties of homoscorpionate tris(pyrazol-1-yl)methane complexes is presented. The relationship between structural features and catalytic efficiency toward the oxidative functionalization of inexpensive and abundant raw-materials to added-value products is also addressed. Full article
(This article belongs to the Special Issue New Trends in Scorpionate Catalysts)
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23 pages, 5521 KiB  
Review
Recent Advances in the BiVO4 Photocatalyst for Sun-Driven Water Oxidation: Top-Performing Photoanodes and Scale-Up Challenges
by Kristine Rodulfo Tolod 1,2, Simelys Hernández 1,3,* and Nunzio Russo 1
1 Politecnico di Torino, Corso Duca degli Abruzzi, 10129 Turin, Italy
2 Ecole Doctorale de Chimie, Université Claude Bernard Lyon 1, Villeurbanne Cedex, 69622 Lyon, France
3 Center for Sustainable Future Technologies (CSF@POLITO), Istituto Italiano di Tecnologia, 10129 Turin, Italy
Catalysts 2017, 7(1), 13; https://doi.org/10.3390/catal7010013 - 1 Jan 2017
Cited by 227 | Viewed by 20450
Abstract
Photoelectrochemical (PEC) water splitting, which is a type of artificial photosynthesis, is a sustainable way of converting solar energy into chemical energy. The water oxidation half-reaction has always represented the bottleneck of this process because of the thermodynamic and kinetic challenges that are [...] Read more.
Photoelectrochemical (PEC) water splitting, which is a type of artificial photosynthesis, is a sustainable way of converting solar energy into chemical energy. The water oxidation half-reaction has always represented the bottleneck of this process because of the thermodynamic and kinetic challenges that are involved. Several materials have been explored and studied to address the issues pertaining to solar water oxidation. Significant advances have recently been made in the use of stable and relatively cheap metal oxides, i.e., semiconducting photocatalysts. The use of BiVO4 for this purpose can be considered advantageous because this catalyst is able to absorb a substantial portion of the solar spectrum and has favourable conduction and valence band edge positions. However, BiVO4 is also associated with poor electron mobility and slow water oxidation kinetics and these are the problems that are currently being investigated in the ongoing research in this field. This review focuses on the most recent advances in the best-performing BiVO4-based photoanodes to date. It summarizes the critical parameters that contribute to the performance of these photoanodes, and highlights so far unresolved critical features related to the scale-up of a BiVO4-based PEC water-splitting device. Full article
(This article belongs to the Special Issue Water Oxidation Catalysis)
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21 pages, 3464 KiB  
Article
Lipase B from Candida antarctica Immobilized on a Silica-Lignin Matrix as a Stable and Reusable Biocatalytic System
by Jakub Zdarta 1, Lukasz Klapiszewski 1, Artur Jedrzak 1, Marek Nowicki 2, Dariusz Moszynski 3 and Teofil Jesionowski 1,*
1 Institute of Chemical Technology and Engineering, Faculty of Chemical Technology, Poznan University of Technology, Berdychowo 4, 60965 Poznan, Poland
2 Institute of Physics, Faculty of Technical Physics, Poznan University of Technology, Piotrowo 3, 60965 Poznan, Poland
3 Institute of Chemical and Environmental Engineering, Faculty of Chemical Technology and Engineering, West Pomeranian University of Technology, Pulaskiego 10, 70322 Szczecin, Poland
Catalysts 2017, 7(1), 14; https://doi.org/10.3390/catal7010014 - 31 Dec 2016
Cited by 55 | Viewed by 10866
Abstract
A study was conducted of the possible use of a silica-lignin hybrid as a novel support for the immobilization of lipase B from Candida antarctica. Results obtained by elemental analysis, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and atomic force [...] Read more.
A study was conducted of the possible use of a silica-lignin hybrid as a novel support for the immobilization of lipase B from Candida antarctica. Results obtained by elemental analysis, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM), as well as the determination of changes in porous structure parameters, confirmed the effective immobilization of the enzyme on the surface of the composite matrix. Based on a hydrolysis reaction, a determination was made of the retention of activity of the immobilized lipase, found to be 92% of that of the native enzyme. Immobilization on a silica-lignin matrix produces systems with maximum activity at pH = 8 and at a temperature of 40 °C. The immobilized enzyme exhibited increased thermal and chemical stability and retained more than 80% of its activity after 20 reaction cycles. Moreover immobilized lipase exhibited over 80% of its activity at pH range 7–9 and temperature from 30 °C to 60 °C, while native Candida antarctica lipase B (CALB) exhibited the same only at pH = 7 and temperature of 30 °C. Full article
(This article belongs to the Special Issue Immobilized Enzymes: Strategies for Enzyme Stabilization)
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20 pages, 3947 KiB  
Article
Response Surface Methodology and Aspen Plus Integration for the Simulation of the Catalytic Steam Reforming of Ethanol
by Bernay Cifuentes, Manuel Figueredo and Martha Cobo *
Energy, Materials and Environment Laboratory, Department of Chemical Engineering, Universidad de La Sabana, Campus Universitario Puente del Común, Km. 7 Autopista Norte, Bogotá 250001, Colombia
Catalysts 2017, 7(1), 15; https://doi.org/10.3390/catal7010015 - 14 Jan 2017
Cited by 26 | Viewed by 14038
Abstract
The steam reforming of ethanol (SRE) on a bimetallic RhPt/CeO2 catalyst was evaluated by the integration of Response Surface Methodology (RSM) and Aspen Plus (version 9.0, Aspen Tech, Burlington, MA, USA, 2016). First, the effect of the Rh–Pt weight ratio (1:0, 3:1, [...] Read more.
The steam reforming of ethanol (SRE) on a bimetallic RhPt/CeO2 catalyst was evaluated by the integration of Response Surface Methodology (RSM) and Aspen Plus (version 9.0, Aspen Tech, Burlington, MA, USA, 2016). First, the effect of the Rh–Pt weight ratio (1:0, 3:1, 1:1, 1:3, and 0:1) on the performance of SRE on RhPt/CeO2 was assessed between 400 to 700 °C with a stoichiometric steam/ethanol molar ratio of 3. RSM enabled modeling of the system and identification of a maximum of 4.2 mol H2/mol EtOH (700 °C) with the Rh0.4Pt0.4/CeO2 catalyst. The mathematical models were integrated into Aspen Plus through Excel in order to simulate a process involving SRE, H2 purification, and electricity production in a fuel cell (FC). An energy sensitivity analysis of the process was performed in Aspen Plus, and the information obtained was used to generate new response surfaces. The response surfaces demonstrated that an increase in H2 production requires more energy consumption in the steam reforming of ethanol. However, increasing H2 production rebounds in more energy production in the fuel cell, which increases the overall efficiency of the system. The minimum H2 yield needed to make the system energetically sustainable was identified as 1.2 mol H2/mol EtOH. According to the results of the integration of RSM models into Aspen Plus, the system using Rh0.4Pt0.4/CeO2 can produce a maximum net energy of 742 kJ/mol H2, of which 40% could be converted into electricity in the FC (297 kJ/mol H2 produced). The remaining energy can be recovered as heat. Full article
(This article belongs to the Special Issue Reforming Catalysts)
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27 pages, 1383 KiB  
Review
Catalyst, Membrane, Free Electrolyte Challenges, and Pathways to Resolutions in High Temperature Polymer Electrolyte Membrane Fuel Cells
by Timothy Myles 1, Leonard Bonville 1 and Radenka Maric 1,2,3,*
1 Center for Clean Energy Engineering, University of Connecticut, Storrs, CT 06269, USA
2 Department of Material Science and Engineering, University of Connecticut, Storrs, CT 06269, USA
3 Department of Chemical & Biomolecular Engineering, University of Connecticut, Storrs, CT 06269, USA
Catalysts 2017, 7(1), 16; https://doi.org/10.3390/catal7010016 - 6 Jan 2017
Cited by 42 | Viewed by 8315
Abstract
High temperature polymer electrolyte membrane fuel cells (HT-PEMFCs) are being studied due to a number of benefits offered versus their low temperature counterparts, including co-generation of heat and power, high tolerance to fuel impurities, and simpler system design. Approximately 90% of the literature [...] Read more.
High temperature polymer electrolyte membrane fuel cells (HT-PEMFCs) are being studied due to a number of benefits offered versus their low temperature counterparts, including co-generation of heat and power, high tolerance to fuel impurities, and simpler system design. Approximately 90% of the literature on HT-PEM is related to the electrolyte and, for the most part, these electrolytes all use free phosphoric acid, or similar free acid, as the ion conductor. A major issue with using phosphoric acid based electrolytes is the free acid in the electrodes. The presence of the acid on the catalyst sites leads to poor oxygen activity, low solubility/diffusion, and can block electrochemical sites through phosphate adsorption. This review will focus on these issues and the steps that have been taken to alleviate these obstacles. The intention is this review may then serve as a tool for finding a solution path in the community. Full article
(This article belongs to the Special Issue Catalysis in Membrane Reactors)
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13 pages, 2312 KiB  
Article
Hydrochlorination of Acetylene Catalyzed by an Activated Carbon-Supported Ammonium Hexachlororuthenate Complex
by Junjie Gu, Yumiao Gao, Jinli Zhang, Wei Li, Yanzhao Dong and You Han *
School of Chemical Engineering & Technology, Tianjin University, Tianjin 300350, China
Catalysts 2017, 7(1), 17; https://doi.org/10.3390/catal7010017 - 10 Jan 2017
Cited by 20 | Viewed by 6298
Abstract
Ammonium hexachlororuthenate ((NH4)2RuCl6) complex was used as a catalyst precursor and coconut activated carbon (AC) was used as the support in the preparation process of the Ru-based catalyst. (NH4)2RuCl6/AC catalyst was [...] Read more.
Ammonium hexachlororuthenate ((NH4)2RuCl6) complex was used as a catalyst precursor and coconut activated carbon (AC) was used as the support in the preparation process of the Ru-based catalyst. (NH4)2RuCl6/AC catalyst was prepared via an incipient wetness impregnation method and assessed in an acetylene hydrochlorination reaction. Meanwhile, the (NH4)2RuCl6/AC catalyst was analyzed with low-temperature N2 adsorption/desorption, thermogravimetry (TG), transmission electron microscopy (TEM), temperature programmed reduction (TPR), X-ray photoelectron spectra (XPS), and temperature programmed desorption (TPD) techniques. Catalytic performance test results show that the (NH4)2RuCl6/AC catalyst exhibits a superior catalytic activity with the highest acetylene conversion of 90.5% under the conditions of 170 °C and an acetylene gas hourly space velocity of 180 h−1. The characterization results illustrate that the presence of the NH4+ cation can inhibit coke deposition as well as the agglomeration of ruthenium particles, and it can also enhance the adsorption ability for reactant HCl, hence improving the catalytic activity and stability. Full article
(This article belongs to the Special Issue Ruthenium Catalysts)
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9 pages, 3093 KiB  
Article
Facile Sonication Synthesis of WS2 Quantum Dots for Photoelectrochemical Performance
by Liyan Zhou 1, Shancheng Yan 2,*, Han Wu 1, Haizeng Song 2 and Yi Shi 1,*
1 National Laboratory of Solid State Microstructures, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China
2 School of Geography and Biological Information, Nanjing University of Posts and Telecommunications, Nanjing 210023, China
Catalysts 2017, 7(1), 18; https://doi.org/10.3390/catal7010018 - 6 Jan 2017
Cited by 29 | Viewed by 11406
Abstract
Two-dimensional transition metal dichalcogenides, such as tungsten disulfide (WS2), have been actively studied as suitable candidates for photocatalysts due to their unique structural and electronic properties. The presence of active sites at the edges and the higher specific surface area of [...] Read more.
Two-dimensional transition metal dichalcogenides, such as tungsten disulfide (WS2), have been actively studied as suitable candidates for photocatalysts due to their unique structural and electronic properties. The presence of active sites at the edges and the higher specific surface area of these materials are crucial to the photocatalytic activity of the hydrogen evolution reaction. Here, WS2 quantum dots (QDs) have been successfully synthesized by using a combination of grinding and sonication techniques. The morphology of the QDs was observed, using transmission electron microscopy and an atomic force microscope, to have uniform sizes of less than 5 nm. Photoelectrochemical (PEC) measurements show that the current density of WS2 QDs under illumination is almost two times higher than that of pristine WS2. Furthermore, these high-quality WS2 QDs may have various applications in optoelectronics, solar cells, and biomedicine. Full article
(This article belongs to the Special Issue Soluble Nanoparticles in Catalytic Applications)
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11 pages, 6327 KiB  
Article
Core-Shell MnO2-SiO2 Nanorods for Catalyzing the Removal of Dyes from Water
by Wei Gong, Xianling Meng, Xiaohong Tang and Peijun Ji *
Department of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029, China
Catalysts 2017, 7(1), 19; https://doi.org/10.3390/catal7010019 - 6 Jan 2017
Cited by 33 | Viewed by 7863
Abstract
This work presented a novel core-shell MnO2@m-SiO2 for catalyzing the removal of dyes from wastewater. MnO2 nanorods were sequentially coated with polydopamine (PDA) and polyethyleneimine (PEI) forming MnO2@PDA-PEI. By taking advantage of the positively charged amine groups, [...] Read more.
This work presented a novel core-shell MnO2@m-SiO2 for catalyzing the removal of dyes from wastewater. MnO2 nanorods were sequentially coated with polydopamine (PDA) and polyethyleneimine (PEI) forming MnO2@PDA-PEI. By taking advantage of the positively charged amine groups, MnO2@PDA-PEI was further silicificated, forming MnO2@PDA-PEI-SiO2. After calcination, the composite MnO2@m-SiO2 was finally obtained. MnO2 nanorod is the core and mesoporous SiO2 (m-SiO2) is the shell. MnO2@m-SiO2 has been used to degrade a model dye Rhodamine B (RhB). The shell m-SiO2 functioned to adsorb/enrich and transfer RhB, and the core MnO2 nanorods oxidized RhB. Thus, MnO2@m-SiO2 combines multiple functions together. Experimental results demonstrated that MnO2@m-SiO2 exhibited a much higher efficiency for degradation of RhB than MnO2. The RhB decoloration and degradation efficiencies were 98.7% and 84.9%, respectively. Consecutive use of MnO2@m-SiO2 has demonstrated that MnO2@m-SiO2 can be used to catalyze multiple cycles of RhB degradation. After six cycles of reuse of MnO2@m-SiO2, the RhB decoloration and degradation efficiencies were 98.2% and 71.1%, respectively. Full article
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14 pages, 4156 KiB  
Article
Plant Extract Mediated Eco-Friendly Synthesis of Pd@Graphene Nanocatalyst: An Efficient and Reusable Catalyst for the Suzuki-Miyaura Coupling
by Mujeeb Khan 1, Mufsir Kuniyil 1, Mohammed Rafi Shaik 1, Merajuddin Khan 1,*, Syed Farooq Adil 1, Abdulrahman Al-Warthan 1, Hamad Z. Alkhathlan 1, Wolfgang Tremel 2, Muhammad Nawaz Tahir 2 and Mohammed Rafiq H. Siddiqui 1,*
1 Department of Chemistry, College of Science, King Saud University, P.O. 2455, Riyadh 11451, Saudi Arabia
2 Institute of Inorganic and Analytical Chemistry, Johannes Gutenberg-University of Mainz, Duesbergweg, 55128 Mainz, Germany
Catalysts 2017, 7(1), 20; https://doi.org/10.3390/catal7010020 - 9 Jan 2017
Cited by 21 | Viewed by 8006
Abstract
Suzuki-Miyaura coupling reaction catalyzed by the palladium (Pd)-based nanomaterials is one of the most versatile methods for the preparation of biaryls. However, use of organic solvents as reaction medium causes a big threat to environment due to the generation of toxic byproducts as [...] Read more.
Suzuki-Miyaura coupling reaction catalyzed by the palladium (Pd)-based nanomaterials is one of the most versatile methods for the preparation of biaryls. However, use of organic solvents as reaction medium causes a big threat to environment due to the generation of toxic byproducts as waste during the work up of these reactions. Therefore, the use of water as reaction media has attracted tremendous attention due to its environmental, economic, and safety benefits. In this study, we report on the synthesis of green Pd@graphene nanocatalyst based on an in situ functionalization approach which exhibited excellent catalytic activity towards the Suzuki–Miyaura cross-coupling reactions of phenyl halides with phenyl boronic acids under facile conditions in water. The green and environmentally friendly synthesis of Pd@graphene nanocatalyst (PG-HRG-Pd) is carried out by simultaneous reduction of graphene oxide (GRO) and PdCl2 using Pulicaria glutinosa extract (PGE) as reducing and stabilizing agent. The phytomolecules present in the plant extract (PE) not only facilitated the reduction of PdCl2, but also helped to stabilize the surface of PG-HRG-Pd nanocatalyst, which significantly enhanced the dispersibility of nanocatalyst in water. The identification of PG-HRG-Pd was established by various spectroscopic and microscopic techniques, including, high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), ultraviolet–visible spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FT-IR), and Raman spectroscopy. The as-prepared PG-HRG-Pd nanocatalyst demonstrated excellent catalytic activity towards the Suzuki-Miyaura cross coupling reactions under aqueous, ligand free, and aerobic conditions. Apart from this the reusability of the catalyst was also evaluated and the catalyst yielded excellent results upon reuse for several times with marginal loss of its catalytic performance. Therefore, the method developed for the green synthesis of PG-HRG-Pd nanocatalyst and the eco-friendly protocol used for the Suzuki coupling offers a mild and effective substitute to the existing protocols and may significantly contribute to the endeavors of green chemistry. Full article
(This article belongs to the Special Issue Suzuki–Miyaura Cross-Coupling Reaction and Potential Applications)
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11 pages, 3267 KiB  
Article
Core-Shell Structured Ni@SiO2 Catalysts Exhibiting Excellent Catalytic Performance for Syngas Methanation Reactions
by Yang Han 1, Bo Wen 1 and Mingyuan Zhu 1,2,*
1 School of Chemistry and Chemical Engineering of Shihezi University, Shihezi 832000, Xinjiang, China
2 Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan, Shihezi 832000, Xinjiang, China
Catalysts 2017, 7(1), 21; https://doi.org/10.3390/catal7010021 - 9 Jan 2017
Cited by 21 | Viewed by 7474
Abstract
In this study, we prepared core-shell structured Ni@SiO2 catalysts using chemical precipitation and modified Stöber methods. The obtained Ni@SiO2 samples exhibited excellent catalysis performances, including high CO conversion of 99.0% and CH4 yield of 89.8%. Moreover, Ni@SiO2 exhibited excellent [...] Read more.
In this study, we prepared core-shell structured Ni@SiO2 catalysts using chemical precipitation and modified Stöber methods. The obtained Ni@SiO2 samples exhibited excellent catalysis performances, including high CO conversion of 99.0% and CH4 yield of 89.8%. Moreover, Ni@SiO2 exhibited excellent catalytic stability during a 100 h lifetime test, which was superior to that of the Ni/SiO2 catalyst. The prepared samples were characterized using a series of techniques, and the results indicated that the catalytic performance for syngas methanation reaction of the Ni@SiO2 sample was markedly improved owing to its nanoreactor structure. The strong interaction between the Ni core and the SiO2 shell effectively restrained the growth of particles, and the deposition of C species. Full article
(This article belongs to the Special Issue C1 Chemistry—C1-Platform Chemicals as Cornerstone for a Sustainable Energy)
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21 pages, 9379 KiB  
Article
Synthesis and Application of Novel Ruthenium Catalysts for High Temperature Alkene Metathesis
by Tegene T. Tole, Jean I. Du Toit, Cornelia G. C. E. Van Sittert, Johan H. L. Jordaan and Hermanus C. M. Vosloo *
Research Focus Area for Chemical Resource Beneficiation, Catalysis and Synthesis Research Group, North-West University, Hoffmann Street, 2531 Potchefstroom, South Africa
Catalysts 2017, 7(1), 22; https://doi.org/10.3390/catal7010022 - 10 Jan 2017
Cited by 8 | Viewed by 5820
Abstract
Four pyridinyl alcohols and the corresponding hemilabile pyridinyl alcoholato ruthenium carbene complexes of the Grubbs second generation-type RuCl(H2IMes)(O^N)(=CHPh), where O^N = 1-(2′-pyridinyl)-1,1-diphenyl methanolato, 1-(2′-pyridinyl)-1-(2′-chlorophenyl),1-phenyl methanolato, 1-(2′-pyridinyl)-1-(4′-chlorophenyl),1-phenyl methanolato and 1-(2′-pyridinyl)-1-(2′-methoxyphenyl),1-phenyl methanolato, are synthesized in very good yields. At high temperatures, the precatalysts [...] Read more.
Four pyridinyl alcohols and the corresponding hemilabile pyridinyl alcoholato ruthenium carbene complexes of the Grubbs second generation-type RuCl(H2IMes)(O^N)(=CHPh), where O^N = 1-(2′-pyridinyl)-1,1-diphenyl methanolato, 1-(2′-pyridinyl)-1-(2′-chlorophenyl),1-phenyl methanolato, 1-(2′-pyridinyl)-1-(4′-chlorophenyl),1-phenyl methanolato and 1-(2′-pyridinyl)-1-(2′-methoxyphenyl),1-phenyl methanolato, are synthesized in very good yields. At high temperatures, the precatalysts showed high stability, selectivity and activity in 1-octene metathesis compared to the Grubbs first and second generation precatalysts. The 2-/4-chloro- and 4-methoxy-substituted pyridinyl alcoholato ligand-containing ruthenium precatalysts showed high performance in the 1-octene metathesis reaction in the range 80–110 °C. The hemilabile 4-methoxy-substituted pyridinyl alcoholato ligand improved the catalyst stability, activity and selectivity for 1-octene metathesis significantly at 110 °C. Full article
(This article belongs to the Special Issue Ruthenium Catalysts)
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12 pages, 4869 KiB  
Article
Catalytic Ammonia Decomposition over High-Performance Ru/Graphene Nanocomposites for Efficient COx-Free Hydrogen Production
by Gang Li 1, Masakoto Kanezashi 2 and Toshinori Tsuru 2,*
1 School of Light Industry and Engineering, South China University of Technology, 381 Wushan Road, Guangzhou 510641, China
2 Department of Chemical Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima 739-8527, Japan
Catalysts 2017, 7(1), 23; https://doi.org/10.3390/catal7010023 - 11 Jan 2017
Cited by 45 | Viewed by 8275
Abstract
Highly-dispersed Ru nanoparticles were grown on graphene nanosheets by simultaneously reducing graphene oxide and Ru ions using ethylene glycol (EG), and the resultant Ru/graphene nanocomposites were applied as a catalyst to ammonia decomposition for COx-free hydrogen production. Tuning the microstructures of [...] Read more.
Highly-dispersed Ru nanoparticles were grown on graphene nanosheets by simultaneously reducing graphene oxide and Ru ions using ethylene glycol (EG), and the resultant Ru/graphene nanocomposites were applied as a catalyst to ammonia decomposition for COx-free hydrogen production. Tuning the microstructures of Ru/graphene nanocomposites was easily accomplished in terms of Ru particle size, morphology, and loading by adjusting the preparation conditions. This was the key to excellent catalytic activity, because ammonia decomposition over Ru catalysts is structure-sensitive. Our results demonstrated that Ru/graphene prepared using water as a co-solvent greatly enhanced the catalytic performance for ammonia decomposition, due to the significantly improved nano architectures of the composites. The long-term stability of Ru/graphene catalysts was evaluated for COx-free hydrogen production from ammonia at high temperatures, and the structural evolution of the catalysts was investigated during the catalytic reactions. Although there were no obvious changes in the catalytic activities at 450 °C over a duration of 80 h, an aggregation of the Ru nanoparticles was still observed in the nanocomposites, which was ascribed mainly to a sintering effect. However, the performance of the Ru/graphene catalyst was decreased gradually at 500 °C within 20 h, which was ascribed mainly to both the effect of the methanation of the graphene nanosheet under a H2 atmosphere and to enhanced sintering under high temperatures. Full article
(This article belongs to the Special Issue Ruthenium Catalysts)
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5 pages, 219 KiB  
Editorial
Acknowledgement to Reviewers of Catalysts in 2016
by Catalysts Editorial Office
MDPI AG, St. Alban-Anlage 66, 4052 Basel, Switzerland
Catalysts 2017, 7(1), 24; https://doi.org/10.3390/catal7010024 - 11 Jan 2017
Cited by 1 | Viewed by 3750
Abstract
The editors of Catalysts would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2016.[...] Full article
13 pages, 6488 KiB  
Article
Cobalt-Doped Carbon Gels as Electro-Catalysts for the Reduction of CO2 to Hydrocarbons
by Abdalla Abdelwahab 1,†, Jesica Castelo-Quibén 1, María Pérez-Cadenas 2, Abdelhakim Elmouwahidi 1, Francisco J. Maldonado-Hódar 1, Francisco Carrasco-Marín 1 and Agustín F. Pérez-Cadenas 1,*
1 Carbon Materials Research Group, Department of Inorganic Chemistry, Faculty of Sciences, University of Granada, Campus Fuentenueva s/n, Granada 18071, Spain
2 Department of Inorganic and Technical Chemistry, Science Faculty, UNED, Paseo Senda del Rey 9, Madrid ES28040, Spain
† Present address: Materials Science and Nanotechnology Department, Faculty of Postgraduate Studies for Advanced Sciences, Beni-Suef University, Beni-Suef 62511, Egypt.
Catalysts 2017, 7(1), 25; https://doi.org/10.3390/catal7010025 - 12 Jan 2017
Cited by 27 | Viewed by 6954
Abstract
Two original series of carbon gels doped with different cobalt loadings and well-developed mesoporosity, aerogels and xerogels, have been prepared, exhaustively characterized, and tested as cathodes for the electro-catalytic reduction of CO2 to hydrocarbons at atmospheric pressure. Commercial cobalt and graphite sheets [...] Read more.
Two original series of carbon gels doped with different cobalt loadings and well-developed mesoporosity, aerogels and xerogels, have been prepared, exhaustively characterized, and tested as cathodes for the electro-catalytic reduction of CO2 to hydrocarbons at atmospheric pressure. Commercial cobalt and graphite sheets have also been tested as cathodes for comparison. All of the doped carbon gels catalyzed the formation of hydrocarbons, at least from type C1 to C4. The catalytic activity depends mainly on the metal loading, nevertheless, the adsorption of a part of the products in the porous structure of the carbon gel cannot be ruled out. Apparent faradaic efficiencies calculated with these developed materials were better that those obtained with a commercial cobalt sheet as a cathode, especially considering the much lower amount of cobalt contained in the Co-doped carbon gels. The cobalt-carbon phases formed in these types of doped carbon gels improve the selectivity to C3-C4 hydrocarbons formation, obtaining even more C3 hydrocarbons than CH4 in some cases. Full article
(This article belongs to the Special Issue Sol–Gel Chemistry: A Toolbox for Catalyst Preparation)
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14 pages, 4218 KiB  
Article
Chitosan–Collagen Coated Magnetic Nanoparticles for Lipase Immobilization—New Type of “Enzyme Friendly” Polymer Shell Crosslinking with Squaric Acid
by Marta Ziegler-Borowska 1,*, Dorota Chelminiak-Dudkiewicz 1, Tomasz Siódmiak 2, Adam Sikora 2, Katarzyna Wegrzynowska-Drzymalska 1, Joanna Skopinska-Wisniewska 1, Halina Kaczmarek 1 and Michał P. Marszałł 2
1 Faculty of Chemistry, Nicolaus Copernicus University in Torun, Gagarina 7, 87-100 Torun, Poland
2 Faculty of Pharmacy, Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University in Torun, dr A. Jurasza 2, 85-089 Bydgoszcz, Poland
Catalysts 2017, 7(1), 26; https://doi.org/10.3390/catal7010026 - 14 Jan 2017
Cited by 47 | Viewed by 10015
Abstract
This article presents a novel route for crosslinking a polysaccharide and polysaccharide/protein shell coated on magnetic nanoparticles (MNPs) surface via condensation reaction with squaric acid (SqA). The syntheses of four new types of collagen-, chitosan-, and chitosan–collagen coated magnetic nanoparticles as supports for [...] Read more.
This article presents a novel route for crosslinking a polysaccharide and polysaccharide/protein shell coated on magnetic nanoparticles (MNPs) surface via condensation reaction with squaric acid (SqA). The syntheses of four new types of collagen-, chitosan-, and chitosan–collagen coated magnetic nanoparticles as supports for enzyme immobilization have been done. Structure and morphology of prepared new materials were characterized by attenuated total reflectance Fourier-transform infrared (ATR-FTIR), XRD, and TEM analysis. Next, the immobilization of lipase from Candida rugosa was performed on the nanoparticles surface via N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (EDC)/N-hydroxy-succinimide (NHS) mechanism. The best results of lipase activity recovery and specific activities were observed for nanoparticles with polymer shell crosslinked via a novel procedure with squaric acid. The specific activity for lipase immobilized on materials crosslinked with SqA (52 U/mg lipase) was about 2-fold higher than for enzyme immobilized on MNPs with glutaraldehyde addition (26 U/mg lipase). Moreover, a little hyperactivation of lipase immobilized on nanoparticles with SqA was observed (104% and 112%). Full article
(This article belongs to the Special Issue Immobilized Enzymes: Strategies for Enzyme Stabilization)
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9 pages, 3006 KiB  
Communication
Aziridine- and Azetidine-Pd Catalytic Combinations. Synthesis and Evaluation of the Ligand Ring Size Impact on Suzuki-Miyaura Reaction Issues
by Hamza Boufroura, Benjamin Large, Talia Bsaibess, Serge Perato, Vincent Terrasson, Anne Gaucher and Damien Prim *
Institut Lavoisier de Versailles, UMR CNRS 8180, Université de Versailles Saint-Quentin-en-Yvelines, 45 Avenue des Etats-Unis, 78035 Versailles CEDEX, France
Catalysts 2017, 7(1), 27; https://doi.org/10.3390/catal7010027 - 13 Jan 2017
Cited by 4 | Viewed by 6157
Abstract
The synthesis of new vicinal diamines based on aziridine and azetidine cores as well as the comparison of their catalytic activities as ligand in the Suzuki-Miyaura coupling reaction are described in this communication. The synthesis of three- and four-membered ring heterocycles substituted by [...] Read more.
The synthesis of new vicinal diamines based on aziridine and azetidine cores as well as the comparison of their catalytic activities as ligand in the Suzuki-Miyaura coupling reaction are described in this communication. The synthesis of three- and four-membered ring heterocycles substituted by a methylamine pendant arm is detailed from the parent nitrile derivatives. Complexation to palladium under various conditions has been examined affording vicinal diamines or amine-imidate complexes. The efficiency of four new catalytic systems is compared in the preparation of variously substituted biaryls. Aziridine- and azetidine-based catalytic systems allowed Suzuki-Miyaura reactions from aryl halides including chlorides with catalytic loadings until 0.001% at temperatures ranging from 100 °C to r.t. The evolution of the Pd-metallacycle ring strain moving from azetidine to aziridine in combination with a methylamine or an imidate pendant arm impacted the Suzuki-Miyaura reaction issue. Full article
(This article belongs to the Special Issue Suzuki–Miyaura Cross-Coupling Reaction and Potential Applications)
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13 pages, 2482 KiB  
Article
The Effect of Sr Addition in Cu- and Fe-Modified CeO2 and ZrO2 Soot Combustion Catalysts
by Verónica Rico-Pérez, Eleonora Aneggi * and Alessandro Trovarelli
Dipartimento Politecnico di Ingegneria e Architettura, Università degli Studi di Udine, via Cotonificio 108, 33100 Udine, Italy
Catalysts 2017, 7(1), 28; https://doi.org/10.3390/catal7010028 - 17 Jan 2017
Cited by 17 | Viewed by 6682
Abstract
This study investigates the activity of transition and alkaline-earth metal-doped catalysts supported on ceria or zirconia for the NOx-assisted oxidation of diesel particulate. A series of Cu- and Fe-impregnated catalysts over CeO2 and ZrO2 supports were prepared by incipient [...] Read more.
This study investigates the activity of transition and alkaline-earth metal-doped catalysts supported on ceria or zirconia for the NOx-assisted oxidation of diesel particulate. A series of Cu- and Fe-impregnated catalysts over CeO2 and ZrO2 supports were prepared by incipient wetness impregnation and characterized by BET, X-ray diffraction (XRD), and temperature-programmed reduction (TPR) experiments while their catalytic activity was investigated in NOx-assisted reaction by means of temperature programmed oxidation experiments (TPO). Higher activity was achieved by copper modified catalysts; the addition of Sr positively affected the performance of the materials, suggesting a synergic effect between transition metals and alkaline-earth metal. The role of copper is correlated to the oxidation of NO to NO2, while strontium seems to be mainly involved in the storage of NOx species. Full article
(This article belongs to the Special Issue Ceria-based Catalysts)
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9 pages, 3590 KiB  
Article
Visualization of Gas Distribution in a Model AP-XPS Reactor by PLIF: CO Oxidation over a Pd(100) Catalyst
by Jianfeng Zhou 1,*, Sara Blomberg 2, Johan Gustafson 2, Edvin Lundgren 2 and Johan Zetterberg 1
1 Division of Combustion Physics, Lund University, SE-221 00 Lund, Sweden
2 Division of Synchrotron Radiation Research, Lund University, SE-221 00 Lund, Sweden
Catalysts 2017, 7(1), 29; https://doi.org/10.3390/catal7010029 - 17 Jan 2017
Cited by 23 | Viewed by 6118
Abstract
In situ knowledge of the gas phase around a catalyst is essential to make an accurate correlation between the catalytic activity and surface structure in operando studies. Although ambient pressure X-ray photoelectron spectroscopy (AP-XPS) can provide information on the gas phase as well [...] Read more.
In situ knowledge of the gas phase around a catalyst is essential to make an accurate correlation between the catalytic activity and surface structure in operando studies. Although ambient pressure X-ray photoelectron spectroscopy (AP-XPS) can provide information on the gas phase as well as the surface structure of a working catalyst, the gas phase detected has not been spatially resolved to date, thus possibly making it ambiguous to interpret the AP-XPS spectra. In this work, planar laser-induced fluorescence (PLIF) is used to visualize the CO2 distribution in a model AP-XPS reactor, during CO oxidation over a Pd(100) catalyst. The results show that the gas composition in the vicinity of the sample measured by PLIF is significantly different from that measured by a conventional mass spectrometer connected to a nozzle positioned just above the sample. In addition, the gas distribution above the catalytic sample has a strong dependence on the gas flow and total chamber pressure. The technique presented has the potential to increase our knowledge of the gas phase in AP-XPS, as well as to optimize the design and operating conditions of in situ AP-XPS reactors for catalysis studies. Full article
(This article belongs to the Special Issue In Situ and Operando Characterization in Catalysis)
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13 pages, 6192 KiB  
Article
Synergically Improving Light Harvesting and Charge Transportation of TiO2 Nanobelts by Deposition of MoS2 for Enhanced Photocatalytic Removal of Cr(VI)
by Jie Liu 1, Ying Li 1, Jun Ke 2,*, Zhong Wang 3 and Huining Xiao 1,*
1 School of Environmental Science and Engineering, North China Electric Power University, Baoding 071003, China
2 School of Chemistry and Environmental Engineering, Wuhan Institute of Technology, Wuhan 430072, China
3 Key Laboratory of Biofuels, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
Catalysts 2017, 7(1), 30; https://doi.org/10.3390/catal7010030 - 19 Jan 2017
Cited by 35 | Viewed by 7618
Abstract
Herein, MoS2/TiO2 nanobelts heterojunction have been successfully synthesized by in situ growth method for photocatalytic reduction of Cr(VI). TiO2 nanobelts (NBs) with rough surface were prepared firstly by acidic treatment process, which is beneficial for deposition and growth of [...] Read more.
Herein, MoS2/TiO2 nanobelts heterojunction have been successfully synthesized by in situ growth method for photocatalytic reduction of Cr(VI). TiO2 nanobelts (NBs) with rough surface were prepared firstly by acidic treatment process, which is beneficial for deposition and growth of MoS2 to form heterojunctions. As a result of special energy level offset and nanostructure, MoS2/TiO2 NBs composite were endowed with higher light-harvesting capacity and charge transportation efficiency, which are indispensible merits for excellent photocatalytic activity. The photocatalytic reduction of Cr(VI) reveals that the synthesized MoS2/TiO2 NBs composite have superior photocatalytic ability than other samples. Meanwhile, a photoreduction mechanism is proposed based on the systematic investigation, where the photogenerated electrons are demonstrated as the dominant reductive species to reduce Cr(VI) to Cr(III). Full article
(This article belongs to the Special Issue Heterogeneous Catalysis for Environmental Remediation)
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42 pages, 7206 KiB  
Review
Nanostructured Inorganic Materials at Work in Electrochemical Sensing and Biofuel Cells
by Yaovi Holade 1,*, Sophie Tingry 1, Karine Servat 2, Teko W. Napporn 2, David Cornu 1 and Kouakou Boniface Kokoh 2
1 Institut Européen des Membranes, IEM UMR 5635, CNRS-UM-ENSCM, Place Eugène Bataillon, 34095 Montpellier CEDEX 5, France
2 UMR 7285 CNRS, “Équipe SAMCat”, Université de Poitiers, 4 rue Michel Brunet, B27, TSA 51106, 86073 Poitiers CEDEX 09, France
Catalysts 2017, 7(1), 31; https://doi.org/10.3390/catal7010031 - 18 Jan 2017
Cited by 28 | Viewed by 10582
Abstract
The future of analytical devices, namely (bio)sensors, which are currently impacting our everyday life, relies on several metrics such as low cost, high sensitivity, good selectivity, rapid response, real-time monitoring, high-throughput, easy-to-make and easy-to-handle properties. Fortunately, they can be readily fulfilled by electrochemical [...] Read more.
The future of analytical devices, namely (bio)sensors, which are currently impacting our everyday life, relies on several metrics such as low cost, high sensitivity, good selectivity, rapid response, real-time monitoring, high-throughput, easy-to-make and easy-to-handle properties. Fortunately, they can be readily fulfilled by electrochemical methods. For decades, electrochemical sensors and biofuel cells operating in physiological conditions have concerned biomolecular science where enzymes act as biocatalysts. However, immobilizing them on a conducting substrate is tedious and the resulting bioelectrodes suffer from stability. In this contribution, we provide a comprehensive, authoritative, critical, and readable review of general interest that surveys interdisciplinary research involving materials science and (bio)electrocatalysis. Specifically, it recounts recent developments focused on the introduction of nanostructured metallic and carbon-based materials as robust “abiotic catalysts” or scaffolds in bioelectrochemistry to boost and increase the current and readout signals as well as the lifetime. Compared to biocatalysts, abiotic catalysts are in a better position to efficiently cope with fluctuations of temperature and pH since they possess high intrinsic thermal stability, exceptional chemical resistance and long-term stability, already highlighted in classical electrocatalysis. We also diagnosed their intrinsic bottlenecks and highlighted opportunities of unifying the materials science and bioelectrochemistry fields to design hybrid platforms with improved performance. Full article
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25 pages, 2017 KiB  
Review
A Short Review on the Catalytic Activity of Hydrotalcite-Derived Materials for Dry Reforming of Methane
by Radosław Dębek 1,2, Monika Motak 1, Teresa Grzybek 1, Maria Elena Galvez 2 and Patrick Da Costa 2,*
1 Faculty of Energy and Fuels, AGH University of Science and Technology, 30 A.Mickiewicza Av., 30-059 Kraków, Poland
2 Institut Jean Le Rond d’Alembert, Sorbonne Universités, UPMC, Univ. Paris 6, CNRS, UMR 7190, 2 Place de la Gare de Ceinture, 78210 Saint-Cyr-L’Ecole, France
Catalysts 2017, 7(1), 32; https://doi.org/10.3390/catal7010032 - 18 Jan 2017
Cited by 121 | Viewed by 20245
Abstract
Nickel-containing hydrotalcite-derived materials have been recently proposed as promising materials for methane dry reforming (DRM). Based on a literature review and on the experience of the authors, this review focuses on presenting past and recent achievements on increasing activity and stability of hydrotalcite-based [...] Read more.
Nickel-containing hydrotalcite-derived materials have been recently proposed as promising materials for methane dry reforming (DRM). Based on a literature review and on the experience of the authors, this review focuses on presenting past and recent achievements on increasing activity and stability of hydrotalcite-based materials for DRM. The use of different NiMgAl and NiAl hydrotalcite (HT) precursors, various methods for nickel introduction into HT structure, calcination conditions and promoters are discussed. HT-derived materials containing nickel generally exhibit high activity in DRM; however, the problem of preventing catalyst deactivation by coking, especially below 700 °C, is still an open question. The proposed solutions in the literature include: catalyst regeneration either in oxygen atmosphere or via hydrogasification; or application of various promoters, such as Zr, Ce or La, which was proven to enhance catalytic stability. Full article
(This article belongs to the Special Issue Reforming Catalysts)
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10 pages, 11480 KiB  
Article
Mild and Highly Efficient Copper(I) Inspired Acylation of Alcohols and Polyols
by Enoch A. Mensah * and Lindsey Earl
School of Natural Sciences, Indiana University Southeast, New Albany, IN 47150, USA
Catalysts 2017, 7(1), 33; https://doi.org/10.3390/catal7010033 - 18 Jan 2017
Cited by 9 | Viewed by 6907
Abstract
A new and highly efficient method mediated by tetrakis(acetonitrile)copper(I) triflate for activating both simple and highly hindered anhydrides in the acylation of alcohols and polyols is described. This new acylation method is mild and mostly proceeds at room temperature with low catalyst loading. [...] Read more.
A new and highly efficient method mediated by tetrakis(acetonitrile)copper(I) triflate for activating both simple and highly hindered anhydrides in the acylation of alcohols and polyols is described. This new acylation method is mild and mostly proceeds at room temperature with low catalyst loading. The method is versatile and has been extended to a wide variety of different alcohol substrates to afford the corresponding ester products in good to excellent yields. Full article
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3 pages, 142 KiB  
Editorial
Reflections on Catalytic Selective Oxidation: Opportunities and Challenges
by Stuart H. Taylor
Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, UK
Catalysts 2017, 7(1), 34; https://doi.org/10.3390/catal7010034 - 20 Jan 2017
Cited by 5 | Viewed by 4576
Abstract
Currently, and looking forward, there is an ever increasing demand to perform chemical transformations with optimized atom and energy efficiency [...] Full article
(This article belongs to the Special Issue Catalysts for Selective Oxidation)
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