Catalysts

1498 KiB

Open AccessReview

The Use of Palladium on Magnetic Support as Catalyst for Suzuki–Miyaura Cross-Coupling Reactions

by Magne O. Sydnes

Catalysts 2017, 7(1), 35; https://doi.org/10.3390/catal7010035 - 23 Jan 2017

Cited by 46 | Viewed by 8738

The development of new solid supports for palladium has received a lot of interest lately. These catalysts have been tested in a range of cross-coupling reactions, such as Suzuki–Miyaura, Mizoroki-Heck, and Sonogashira cross-coupling reactions, with good outcomes. Attaching the catalyst to a solid [...] Read more.

The development of new solid supports for palladium has received a lot of interest lately. These catalysts have been tested in a range of cross-coupling reactions, such as Suzuki–Miyaura, Mizoroki-Heck, and Sonogashira cross-coupling reactions, with good outcomes. Attaching the catalyst to a solid support simplifies the operations required in order to isolate and recycle the catalyst after a reaction has completed. Palladium on solid supports made of magnetic materials is particularly interesting since such catalysts can be removed very simply by utilizing an external magnet, which withholds the catalyst in the reaction vessel. This review will showcase some of the latest magnetic solid supports for palladium and highlight these catalysts’ performance in Suzuki–Miyaura cross-coupling reactions. Full article

(This article belongs to the Special Issue Suzuki–Miyaura Cross-Coupling Reaction and Potential Applications)

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142 KiB

Open AccessEditorial

Reflections on Catalytic Selective Oxidation: Opportunities and Challenges

by Stuart H. Taylor

Catalysts 2017, 7(1), 34; https://doi.org/10.3390/catal7010034 - 20 Jan 2017

Cited by 4 | Viewed by 4212

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)

6192 KiB

Open AccessArticle

Synergically Improving Light Harvesting and Charge Transportation of TiO₂ Nanobelts by Deposition of MoS₂ for Enhanced Photocatalytic Removal of Cr(VI)

by Jie Liu, Ying Li, Jun Ke, Zhong Wang and Huining Xiao

Catalysts 2017, 7(1), 30; https://doi.org/10.3390/catal7010030 - 19 Jan 2017

Cited by 34 | Viewed by 7266

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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11480 KiB

Open AccessArticle

Mild and Highly Efficient Copper(I) Inspired Acylation of Alcohols and Polyols

by Enoch A. Mensah and Lindsey Earl

Catalysts 2017, 7(1), 33; https://doi.org/10.3390/catal7010033 - 18 Jan 2017

Cited by 9 | Viewed by 6343

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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2017 KiB

Open AccessReview

A Short Review on the Catalytic Activity of Hydrotalcite-Derived Materials for Dry Reforming of Methane

by Radosław Dębek, Monika Motak, Teresa Grzybek, Maria Elena Galvez and Patrick Da Costa

Catalysts 2017, 7(1), 32; https://doi.org/10.3390/catal7010032 - 18 Jan 2017

Cited by 114 | Viewed by 16970

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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7206 KiB

Open AccessReview

Nanostructured Inorganic Materials at Work in Electrochemical Sensing and Biofuel Cells

by Yaovi Holade, Sophie Tingry, Karine Servat, Teko W. Napporn, David Cornu and Kouakou Boniface Kokoh

Catalysts 2017, 7(1), 31; https://doi.org/10.3390/catal7010031 - 18 Jan 2017

Cited by 24 | Viewed by 10009

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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3590 KiB

Open AccessArticle

Visualization of Gas Distribution in a Model AP-XPS Reactor by PLIF: CO Oxidation over a Pd(100) Catalyst

by Jianfeng Zhou, Sara Blomberg, Johan Gustafson, Edvin Lundgren and Johan Zetterberg

Catalysts 2017, 7(1), 29; https://doi.org/10.3390/catal7010029 - 17 Jan 2017

Cited by 22 | Viewed by 5606

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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2482 KiB

Open AccessFeature PaperArticle

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

Catalysts 2017, 7(1), 28; https://doi.org/10.3390/catal7010028 - 17 Jan 2017

Cited by 17 | Viewed by 6290

Abstract

This study investigates the activity of transition and alkaline-earth metal-doped catalysts supported on ceria or zirconia for the NO_x-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 NO_x-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 NO_x-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 NO_x species. Full article

(This article belongs to the Special Issue Ceria-based Catalysts)

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4218 KiB

Open AccessArticle

Chitosan–Collagen Coated Magnetic Nanoparticles for Lipase Immobilization—New Type of “Enzyme Friendly” Polymer Shell Crosslinking with Squaric Acid

by Marta Ziegler-Borowska, Dorota Chelminiak-Dudkiewicz, Tomasz Siódmiak, Adam Sikora, Katarzyna Wegrzynowska-Drzymalska, Joanna Skopinska-Wisniewska, Halina Kaczmarek and Michał P. Marszałł

Catalysts 2017, 7(1), 26; https://doi.org/10.3390/catal7010026 - 14 Jan 2017

Cited by 46 | Viewed by 9425

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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3947 KiB

Open AccessArticle

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

Catalysts 2017, 7(1), 15; https://doi.org/10.3390/catal7010015 - 14 Jan 2017

Cited by 26 | Viewed by 12714

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 Rh_0.4Pt_0.4/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 Rh_0.4Pt_0.4/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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3006 KiB

Open AccessCommunication

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

Catalysts 2017, 7(1), 27; https://doi.org/10.3390/catal7010027 - 13 Jan 2017

Cited by 3 | Viewed by 5593

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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6488 KiB

Open AccessArticle

Cobalt-Doped Carbon Gels as Electro-Catalysts for the Reduction of CO₂ to Hydrocarbons

by Abdalla Abdelwahab, Jesica Castelo-Quibén, María Pérez-Cadenas, Abdelhakim Elmouwahidi, Francisco J. Maldonado-Hódar, Francisco Carrasco-Marín and Agustín F. Pérez-Cadenas

Catalysts 2017, 7(1), 25; https://doi.org/10.3390/catal7010025 - 12 Jan 2017

Cited by 25 | Viewed by 6546

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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219 KiB

Open AccessEditorial

Acknowledgement to Reviewers of Catalysts in 2016

by Catalysts Editorial Office

Catalysts 2017, 7(1), 24; https://doi.org/10.3390/catal7010024 - 11 Jan 2017

Cited by 2 | Viewed by 3585

Abstract

The editors of Catalysts would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2016.[...] Full article

4869 KiB

Open AccessArticle

Catalytic Ammonia Decomposition over High-Performance Ru/Graphene Nanocomposites for Efficient CO_x-Free Hydrogen Production

by Gang Li, Masakoto Kanezashi and Toshinori Tsuru

Catalysts 2017, 7(1), 23; https://doi.org/10.3390/catal7010023 - 11 Jan 2017

Cited by 38 | Viewed by 7606

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 CO_x-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 CO_x-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 CO_x-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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9379 KiB

Open AccessArticle

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

Catalysts 2017, 7(1), 22; https://doi.org/10.3390/catal7010022 - 10 Jan 2017

Cited by 8 | Viewed by 5400

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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2312 KiB

Open AccessArticle

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

Catalysts 2017, 7(1), 17; https://doi.org/10.3390/catal7010017 - 10 Jan 2017

Cited by 18 | Viewed by 5858

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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3267 KiB

Open AccessArticle

Core-Shell Structured Ni@SiO₂ Catalysts Exhibiting Excellent Catalytic Performance for Syngas Methanation Reactions

by Yang Han, Bo Wen and Mingyuan Zhu

Catalysts 2017, 7(1), 21; https://doi.org/10.3390/catal7010021 - 9 Jan 2017

Cited by 15 | Viewed by 6901

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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4156 KiB

Open AccessArticle

Plant Extract Mediated Eco-Friendly Synthesis of Pd@Graphene Nanocatalyst: An Efficient and Reusable Catalyst for the Suzuki-Miyaura Coupling

by Mujeeb Khan, Mufsir Kuniyil, Mohammed Rafi Shaik, Merajuddin Khan, Syed Farooq Adil, Abdulrahman Al-Warthan, Hamad Z. Alkhathlan, Wolfgang Tremel, Muhammad Nawaz Tahir and Mohammed Rafiq H. Siddiqui

Catalysts 2017, 7(1), 20; https://doi.org/10.3390/catal7010020 - 9 Jan 2017

Cited by 21 | Viewed by 7614

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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6327 KiB

Open AccessArticle

Core-Shell MnO₂-SiO₂ Nanorods for Catalyzing the Removal of Dyes from Water

by Wei Gong, Xianling Meng, Xiaohong Tang and Peijun Ji

Catalysts 2017, 7(1), 19; https://doi.org/10.3390/catal7010019 - 6 Jan 2017

Cited by 29 | Viewed by 7427

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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3093 KiB

Open AccessArticle

Facile Sonication Synthesis of WS₂ Quantum Dots for Photoelectrochemical Performance

by Liyan Zhou, Shancheng Yan, Han Wu, Haizeng Song and Yi Shi

Catalysts 2017, 7(1), 18; https://doi.org/10.3390/catal7010018 - 6 Jan 2017

Cited by 25 | Viewed by 10740

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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1383 KiB

Open AccessFeature PaperReview

Catalyst, Membrane, Free Electrolyte Challenges, and Pathways to Resolutions in High Temperature Polymer Electrolyte Membrane Fuel Cells

by Timothy Myles, Leonard Bonville and Radenka Maric

Catalysts 2017, 7(1), 16; https://doi.org/10.3390/catal7010016 - 6 Jan 2017

Cited by 39 | Viewed by 7781

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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990 KiB

Open AccessReview

The Protagonism of Biocatalysis in Green Chemistry and Its Environmental Benefits

by Viridiana Santana Ferreira-Leitão, Magali Christe Cammarota, Erika Cristina Gonçalves Aguieiras, Lívian Ribeiro Vasconcelos de Sá, Roberto Fernandez-Lafuente and Denise Maria Guimarães Freire

Catalysts 2017, 7(1), 9; https://doi.org/10.3390/catal7010009 - 1 Jan 2017

Cited by 64 | Viewed by 10310

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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5521 KiB

Open AccessFeature PaperReview

Recent Advances in the BiVO₄ Photocatalyst for Sun-Driven Water Oxidation: Top-Performing Photoanodes and Scale-Up Challenges

by Kristine Rodulfo Tolod, Simelys Hernández and Nunzio Russo

Catalysts 2017, 7(1), 13; https://doi.org/10.3390/catal7010013 - 1 Jan 2017

Cited by 212 | Viewed by 18564

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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2940 KiB

Open AccessFeature PaperReview

C-Homoscorpionate Oxidation Catalysts—Electrochemical and Catalytic Activity

by Luísa M. D. R. S. Martins

Catalysts 2017, 7(1), 12; https://doi.org/10.3390/catal7010012 - 1 Jan 2017

Cited by 32 | Viewed by 7142

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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13138 KiB

Open AccessArticle

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

Catalysts 2017, 7(1), 11; https://doi.org/10.3390/catal7010011 - 1 Jan 2017

Cited by 9 | Viewed by 8150

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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2414 KiB

Open AccessArticle

N₂O Direct Dissociation over Mg_xCe_yCo_1−x−yCo₂O₄ Composite Spinel Metal Oxide

by Ning Liu, Ping Chen, Yingxia Li and Runduo Zhang

Catalysts 2017, 7(1), 10; https://doi.org/10.3390/catal7010010 - 1 Jan 2017

Cited by 6 | Viewed by 5772

Abstract

A series of Mg- and/or Ce-doped Co₃O₄ (Mg_xCo_1−xCo₂O₄ Ce_xCo_1−xCo₂O₄, Mg_xCe_yCo_1−x−yCo₂O₄) [...] Read more.

A series of Mg- and/or Ce-doped Co₃O₄ (Mg_xCo_1−xCo₂O₄ Ce_xCo_1−xCo₂O₄, Mg_xCe_yCo_1−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 Mg_0.025Ce_0.05Co_0.925Co₂O₄ 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 Mg_0.025Ce_0.05Co_0.925Co₂O₄: (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 Mg_0.025Ce_0.05Co_0.925Co₂O₄ (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 Mg_0.025Ce_0.05Co_0.925Co₂O₄, 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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3464 KiB

Open AccessArticle

Lipase B from Candida antarctica Immobilized on a Silica-Lignin Matrix as a Stable and Reusable Biocatalytic System

by Jakub Zdarta, Lukasz Klapiszewski, Artur Jedrzak, Marek Nowicki, Dariusz Moszynski and Teofil Jesionowski

Catalysts 2017, 7(1), 14; https://doi.org/10.3390/catal7010014 - 31 Dec 2016

Cited by 53 | Viewed by 9715

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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3311 KiB

Open AccessArticle

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, Hiroshi Yano, Takahiro Matsumoto, Donald A. Tryk, Akihiro Iiyama and Hiroyuki Uchida

Catalysts 2017, 7(1), 8; https://doi.org/10.3390/catal7010008 - 29 Dec 2016

Cited by 12 | Viewed by 9680

Abstract

The CO-tolerance mechanism of a carbon-supported Pt-Fe alloy catalyst with two atomic layers of stabilized Pt-skin (Pt_2AL–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 (Pt_2AL–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 CO_ad, reaching the coverage θ_CO ≈ 0.99. The bands in the IR spectra observed on both catalysts were successfully assigned to linearly adsorbed CO (CO_L) and bridged CO (CO_B), both of which consisted of multiple components (CO_L or CO_B at terraces and step/edge sites). The Pt_2AL–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 (CO_{L, 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 CO_{L, terrace} to CO_{L, step/edge}, without removal of CO_ad from the surface. The Pt_2AL–PtFe/C catalyst showed a larger decrease in the band intensity of CO_{L, terrace}. A possible mechanism for the CO-tolerant HOR is also discussed. Full article

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7403 KiB

Open AccessArticle

Dehydrogenative Oxidation of Alcohols Catalyzed by Highly Dispersed Ruthenium Incorporated Titanium Oxide

by Youngyong Kim, Seokhoon Ahn, Jun Yeon Hwang, Doo-Hyun Ko and Ki-Young Kwon

Catalysts 2017, 7(1), 7; https://doi.org/10.3390/catal7010007 - 28 Dec 2016

Cited by 14 | Viewed by 5826

Abstract

Ruthenium incorporated titanium oxides (Ru_xTiO₂) 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 (Ru_xTiO₂) 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 Ru_xTiO₂ (≈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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2512 KiB

Open AccessArticle

Hydrothermal Stability of Ru/SiO₂–C: A Promising Catalyst for Biomass Processing through Liquid-Phase Reactions

by Martín N. Gatti, Bárbara Lombardi, Delia Gazzoli, Gerardo F. Santori, Francisco Pompeo and Nora N. Nichio

Catalysts 2017, 7(1), 6; https://doi.org/10.3390/catal7010006 - 27 Dec 2016

Cited by 5 | Viewed by 5877

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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