Catalysts

Research

14 pages, 3548 KiB

Open AccessArticle

Comparison of Efficiencies and Mechanisms of Catalytic Ozonation of Recalcitrant Petroleum Refinery Wastewater by Ce, Mg, and Ce-Mg Oxides Loaded Al₂O₃

by Chunmao Chen^1,†, Yu Chen^1,†, Brandon A. Yoza², Yuhao Du¹, Yuxian Wang¹, Qing X. Li³

, Lanping Yi¹, Shaohui Guo¹ and Qinghong Wang^1,*

¹ State Key Laboratory of Heavy Oil Processing, State Key Laboratory of Petroleum Pollution Control, China University of Petroleum, Beijing 102249, China

² Hawaii Natural Energy Institute, University of Hawaii at Manoa, Honolulu, HI 96822, USA

³ Department of Molecular Biosciences and Bioengineering, University of Hawaii at Manoa, Honolulu, HI 96822, USA

^† These authors contributed equally to this work.

Catalysts 2017, 7(3), 72; https://doi.org/10.3390/catal7030072 - 24 Feb 2017

Cited by 17 | Viewed by 8098

Abstract

The use of catalytic ozonation processes (COPs) for the advanced treatment of recalcitrant petroleum refinery wastewater (RPRW) is rapidly expanding. In this study, magnesium (Mg), cerium (Ce), and Mg-Ce oxide-loaded alumina (Al₂O₃) were developed as cost efficient catalysts for [...] Read more.

The use of catalytic ozonation processes (COPs) for the advanced treatment of recalcitrant petroleum refinery wastewater (RPRW) is rapidly expanding. In this study, magnesium (Mg), cerium (Ce), and Mg-Ce oxide-loaded alumina (Al₂O₃) were developed as cost efficient catalysts for ozonation treatment of RPRW, having performance metrics that meet new discharge standards. Interactions between the metal oxides and the Al₂O₃ support influence the catalytic properties, as well as the efficiency and mechanism. Mg-Ce/Al₂O₃ (Mg-Ce/Al₂O₃-COP) reduced the chemical oxygen demand by 4.7%, 4.1%, 6.0%, and 17.5% relative to Mg/Al₂O₃-COP, Ce/Al₂O₃-COP, Al₂O₃-COP, and single ozonation, respectively. The loaded composite metal oxides significantly increased the hydroxyl radical-mediated oxidation. Surface hydroxyl groups (–OHs) are the dominant catalytic active sites on Al₂O₃. These active surface –OHs along with the deposited metal oxides (Mg²⁺ and/or Ce⁴⁺) increased the catalytic activity. The Mg-Ce/Al₂O₃ catalyst can be economically produced, has high efficiency, and is stable under acidic and alkaline conditions. Full article

(This article belongs to the Special Issue Heterogeneous Catalysis for Environmental Remediation)

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29 pages, 6661 KiB

Open AccessArticle

Catalytic Dehydration of Glycerol to Acrolein over a Catalyst of Pd/LaY Zeolite and Comparison with the Chemical Equilibrium

by Israel Pala Rosas¹

, José Luis Contreras^2,*, José Salmones¹, Carlos Tapia², Beatriz Zeifert¹, Juan Navarrete³, Tamara Vázquez¹ and Diana Carolina García²

¹ Escuela Superior de Ingeniería Química e Industrias Extractivas, Instituto Politécnico Nacional, Av. Instituto Politécnico Nacional s/n, Col. San Pedro Zacatenco, C.P. 07738 Ciudad de Mexico, Mexico

² Departamento de Energía, CBI, Universidad Autónoma Metropolitana-Azcapotzalco, Av. San Pablo 180, Col. Reynosa, C.P. 02200 Ciudad de Mexico, Mexico

³ Instituto Mexicano del Petróleo, Eje Central Lázaro Cárdenas 152, Col. San Bartolo Atepehuacán, C.P. 07730 Ciudad de Mexico, Mexico

Catalysts 2017, 7(3), 73; https://doi.org/10.3390/catal7030073 - 25 Feb 2017

Cited by 44 | Viewed by 11876

Abstract

Glycerol dehydration to acrolein was studied with three catalysts using zeolite-Y. This zeolite in its protonic form (HY), with La (LaY) and Pd with La (Pd/LaY), was characterized by X-ray diffraction (XRD), Fourier-transform-infrared spectroscopy (FTIR) with pyridine, BET, Scanning Electron Microscope (SEM)–Energy-Dispersive Spectroscopy [...] Read more.

Glycerol dehydration to acrolein was studied with three catalysts using zeolite-Y. This zeolite in its protonic form (HY), with La (LaY) and Pd with La (Pd/LaY), was characterized by X-ray diffraction (XRD), Fourier-transform-infrared spectroscopy (FTIR) with pyridine, BET, Scanning Electron Microscope (SEM)–Energy-Dispersive Spectroscopy X-ray (EDS) and the catalytic activity tests were carried out under H₂ atmosphere. It was found that La ions exchanged in the zeolite-Y resulted in the improvement of both glycerol conversion and yield to acrolein, also a relatively constant glycerol conversion was achieved up to three hours, due to the presence of Pd on the catalyst and H₂ in the feed. The comparison of the calculated and experimental yields obtained from the catalytic tests of the Pd/LaY catalyst indicates a greater activity for the reaction to acrolein than for the reaction to acetol. The calculated equilibrium yields of the dehydration reaction from glycerol to acrolein, acetol, ethanal, methanol, and water and the experimental yields of a Pd/LaY catalyst were compared. Thermodynamically, a complete conversion of glycerol can be achieved since the general system remains exothermic and promotes the path to acetol below 480 K. Above this temperature the system consumes energy and favors the production of acrolein, reaching its maximum concentration at 600 K. Full article

(This article belongs to the Special Issue Catalysis of Biomass-Derived Molecules)

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12 pages, 2021 KiB

Open AccessArticle

Effect of Different Nano-Sized Silica Sols as Supports on the Structure and Properties of Cu/SiO₂ for Hydrogenation of Dimethyl Oxalate

by Chuancai Zhang¹, Denghao Wang², Mingyuan Zhu², Feng Yu²

and Bin Dai^2,*

¹ School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China

² School of Chemistry and Chemical Engineering of Shihezi University, Shihezi 832000, China

Catalysts 2017, 7(3), 75; https://doi.org/10.3390/catal7030075 - 25 Feb 2017

Cited by 16 | Viewed by 6058

Abstract

Cu/x-SiO₂ catalysts with 4, 10, and 20 nm silica sols as supports was produced by ammonia evaporation method and characterized. Different nano-sized silica sols as supports significantly affected the structure and catalytic properties of the copper catalysts for ethylene glycol [...] Read more.

Cu/x-SiO₂ catalysts with 4, 10, and 20 nm silica sols as supports was produced by ammonia evaporation method and characterized. Different nano-sized silica sols as supports significantly affected the structure and catalytic properties of the copper catalysts for ethylene glycol synthesis from dimethyl oxalate. Compared with Cu/20-SiO₂ and Cu/4-SiO₂ catalysts, the catalytic performance and stability of Cu/10-SiO₂ catalyst were greatly enhanced. The Cu/10-SiO₂ catalyst showed 99.9% conversion with 94% EG selectivity and a lifetime of over 3080 h if it is calculated by industrial weight liquid hourly space velocity (WLHSV) of 0.5 h⁻¹. The Cu/10-SiO₂ catalyst has one of the longest lifetimes among the catalysts and is a good alternative catalyst for this reaction. Improvement in the catalytic performance and stability of Cu/10-SiO₂ is attributed to the proper S_BET, D_p and larger dispersion of copper. In addition, the supports of Cu/10-SiO₂ catalyst have smaller particles than that of Cu/20-SiO₂; thus, the migration and growth of copper species in catalysts are restrained during the reaction. Full article

(This article belongs to the Special Issue Mesostructured Materials and Their Catalytic Applications)

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16 pages, 6867 KiB

Open AccessFeature PaperArticle

Suzuki-Miyaura C-C Coupling Reactions Catalyzed by Supported Pd Nanoparticles for the Preparation of Fluorinated Biphenyl Derivatives

by Roghayeh Sadeghi Erami^1,2, Diana Díaz-García¹, Sanjiv Prashar¹

, Antonio Rodríguez-Diéguez³

, Mariano Fajardo¹, Mehdi Amirnasr² and Santiago Gómez-Ruiz^1,*

¹ Departamento de Biología y Geología, Física y Química Inorgánica, ESCET, Universidad Rey Juan Carlos, Calle Tulipán s/n, E-28933 Móstoles (Madrid), Spain

² Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111, Iran

³ Departamento de Química Inorgánica, Universidad de Granada, 18071 Granada, Spain

Catalysts 2017, 7(3), 76; https://doi.org/10.3390/catal7030076 - 28 Feb 2017

Cited by 25 | Viewed by 9584

Abstract

Heterogeneous recyclable catalysts in Suzuki-Miyaura C-C coupling reactions are of great interest in green chemistry as reusable alternatives to homogeneous Pd complexes. Considering the interesting properties of fluorinated compounds for the pharmaceutical industry, as precursors of novel materials, and also as components of [...] Read more.

Heterogeneous recyclable catalysts in Suzuki-Miyaura C-C coupling reactions are of great interest in green chemistry as reusable alternatives to homogeneous Pd complexes. Considering the interesting properties of fluorinated compounds for the pharmaceutical industry, as precursors of novel materials, and also as components of liquid crystalline media, this present study describes the preparation of different fluorinated biphenyl derivatives by Suzuki-Miyaura coupling reactions catalyzed by a heterogeneous system (G-COOH-Pd-10) based on Pd nanoparticles supported onto COOH-modified graphene. The catalytic activity of the hybrid material G-COOH-Pd-10 has been tested in Suzuki-Miyaura C–C coupling reactions observing excellent versatility and good conversion rates in the reactions of phenylboronic acid, 4-vinylphenylboronic acid, 4-carboxyphenylboronic acid, and 4-fluorophenylboronic acid with 1-bromo-4-fluorobenzene. In addition, the influence of the arylbromide has been studied by carrying out reactions of 4-fluorophenylboronic acid with 1-bromo-2-fluorobenzene, 1-bromo-3-fluorobenzene, 1-bromo-4-fluorobenzene, 2-bromo-5-fluorotoluene, and 2-bromo-4-fluorotoluene. Finally, catalyst recyclability tests show a good degree of reusability of the system based on G-COOH-Pd-10 as the decrease in catalytic activity after five consecutive catalytic cycles in the reaction of 1-bromo-4-fluorobenzene with 4-florophenylboronic acid at 48 hours of reaction is lower than 8% while in the case of reactions at three hours the recyclability of the systems is much lower. Full article

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

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9 pages, 1415 KiB

Open AccessArticle

Polymerization of Alkylsilanes on ZIF-8 to Hierarchical Siloxane Microspheres and Microflowers

by Lin Yang, Congjia Xie, Yizhou Li, Lei Guo, Minfang Nie, Jinping Zhang, Zhiying Yan, Jiaqiang Wang^* and Wei Wang^*

Yunnan Provincial Collaborative Innovation Center of Green Chemistry for Lignite Energy, Yunnan Province Engineering Research Center of Photocatalytic Treatment of Industrial Wastewater, The Universities’ Center for Photocatalytic Treatment of Pollutants in Yunnan Province, School of Energy, School of Chemical Sciences & Technology, Yunnan University, Kunming 650091, China

Catalysts 2017, 7(3), 77; https://doi.org/10.3390/catal7030077 - 3 Mar 2017

Cited by 40 | Viewed by 6860

Abstract

The use of metal-organic frameworks (MOFs) in the polymerization field remains comparatively rare up to now, let alone studies on the fabrication of polymer microstructures through a MOFs-catalyzed assembly process. Zeolitic imidazolate framework-8 (ZIF-8), a well-known MOF for its chemical and thermal stabilities, [...] Read more.

The use of metal-organic frameworks (MOFs) in the polymerization field remains comparatively rare up to now, let alone studies on the fabrication of polymer microstructures through a MOFs-catalyzed assembly process. Zeolitic imidazolate framework-8 (ZIF-8), a well-known MOF for its chemical and thermal stabilities, was used to induce a polymerization reaction of saturated alkylsilanes for the first time. The reaction temperature was found to be critical for morphology control of the polymerized ZIF-siloxane composites. The polymerization of alkylsilanes by ZIF-8 at room temperature resulted in siloxane microspheres while rose petal-like microstructures were obtained at higher temperature. The effects of the reaction time on the structures of the polymerization products were also investigated and the polymerization reaction process was proposed. This work expands the field of MOFs’ applications and develops a reasonable method for the multidimensional assembly of MOFs building blocks into required structures or platforms for designing new kinds of hierarchical morphologies, which to our knowledge has not been previously investigated. Full article

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10 pages, 6918 KiB

Open AccessArticle

Two-Dimensional Layered Double Hydroxide Derived from Vermiculite Waste Water Supported Highly Dispersed Ni Nanoparticles for CO Methanation

by Panpan Li¹, Mingyuan Zhu¹, Zhiqun Tian², Yang Han¹, Yu Zhang³, Tuantuan Zhou³

, Lihua Kang¹, Jianming Dan¹, Xuhong Guo^1,4

, Feng Yu^1,*

, Qiang Wang^1,3,* and Bin Dai^1,*

¹ Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan, School of Chemistry and Chemical Engineering, Shihezi University, Shihezi 832003, China

² Collaborative Innovation Center of Renewable Energy Materials, Guangxi University, Nanning 530004, China

³ Environmental Functional Nanomaterials (EFN) Laboratory, College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083, China

⁴ State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China

Catalysts 2017, 7(3), 79; https://doi.org/10.3390/catal7030079 - 7 Mar 2017

Cited by 26 | Viewed by 8899

Abstract

Expanded multilayered vermiculite (VMT) was successfully used as catalyst support and Ni/VMT synthesized by microwave irradiation assisted synthesis (MIAS) exhibited excellent performance in our previous work. We also developed a two-dimensional porous SiO2 nanomesh (2D VMT-SiO2) by mixed-acid etching of VMT. Compared with [...] Read more.

Expanded multilayered vermiculite (VMT) was successfully used as catalyst support and Ni/VMT synthesized by microwave irradiation assisted synthesis (MIAS) exhibited excellent performance in our previous work. We also developed a two-dimensional porous SiO2 nanomesh (2D VMT-SiO2) by mixed-acid etching of VMT. Compared with three-dimensional (3D) MCM-41, 2D VMT-SiO2 as a catalyst support provided a superior position for implantation of NiO species and the as-obtained catalyst exhibited excellent performance. In this paper, we successfully synthesized a layered double hydroxide (LDH) using the spent liquor after mixed-acid etching of VMT, which mainly contained Mg2+ and Al3+. The as-calcined layered double oxide (LDO) was used as a catalyst support for CO methanation. Compared with Ni/MgAl-LDO, Ni/VMT-LDO had smaller active component particles; therefore, in this study, it exhibited excellent catalytic performance over the whole temperature range of 250–500 °C. Ni/VMT-LDO achieved the best activity with 87.88% CO conversion, 89.97% CH4 selectivity, and 12.47 × 10−2·s−1 turn over frequency (TOF) at 400 °C under a gas hourly space velocity of 20,000 mL/g/h. This study demonstrated that VMT-LDO as a catalyst support provided an efficient way to develop high-performance catalysts for synthetic natural gas (SNG) from syngas. Full article

(This article belongs to the Special Issue C1 Chemistry—C1-Platform Chemicals as Cornerstone for a Sustainable Energy)

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10 pages, 2827 KiB

Open AccessArticle

Synthesis of Renewable Diesel Range Alkanes by Hydrodeoxygenation of Palmitic Acid over 5% Ni/CNTs under Mild Conditions

by Yanan Duan¹, Ranran Ding², Yanchun Shi¹, Xiao Fang¹, Husheng Hu¹, Mingde Yang¹ and Yulong Wu^1,3,*

¹ Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084, China

² School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China

³ Beijing Key Laboratory of Fine Ceramics, Beijing 100084, China

Catalysts 2017, 7(3), 81; https://doi.org/10.3390/catal7030081 - 9 Mar 2017

Cited by 14 | Viewed by 6065

Abstract

Recently, the catalytic upgrading of bio-oil to renewable diesel has been attracting more and more attention. In the current paper, carbon nanotube (CNT)-supported nickel catalysts, namely, 5% Ni/CNTs, were prepared for liquid hydrocarbon production through the deoxygenation of palmitic acid, the model compound [...] Read more.

Recently, the catalytic upgrading of bio-oil to renewable diesel has been attracting more and more attention. In the current paper, carbon nanotube (CNT)-supported nickel catalysts, namely, 5% Ni/CNTs, were prepared for liquid hydrocarbon production through the deoxygenation of palmitic acid, the model compound of bio-oil under a mild condition of 240 °C reaction temperature and 2 MPa H₂ pressure. The experimental results revealed that the main reaction product was pentadecane (yield of 89.64%) at an optimum palmitic acid conversion of 97.25% via the hydrodecarbonylation (HDC) process. The deoxygenation mechanism for palmitic acid conversion was also investigated. This study provides technical parameters and a theoretical basis for further industrialization in the bio-oil upgrading process. Full article

(This article belongs to the Special Issue Catalytic Sustainable Processes in Biorefineries)

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13 pages, 4282 KiB

Open AccessArticle

Biotemplated Mesoporous TiO2/SiO2 Composite Derived from Aquatic Plant Leaves for Efficient Dye Degradation

by Zhiying Yan, Jiao He, Lei Guo, Yueting Li, Deliang Duan, Yongjuan Chen, Junjie Li, Fagui Yuan and Jiaqiang Wang ^*

Yunnan Provincial Collaborative Innovation Center of Green Chemistry for Lignite Energy, Yunnan Province Engineering Research Center of Photocatalytic Treatment of Industrial Wastewater, The Universities’ Center for Photocatalytic Treatment of Pollutants in Yunnan Province, School of Chemical Sciences & Technology, School of Energy, Yunnan University, Kunming 650091, China

Catalysts 2017, 7(3), 82; https://doi.org/10.3390/catal7030082 - 9 Mar 2017

Cited by 25 | Viewed by 5946

Abstract

The biotemplating technique is an environmental-protective high-efficiency new technology by which the resulting TiO2 may simultaneously attain the duplication of structure and self-doping elements from biotemplate materials, which is highly desirable for photocatalytic applications. In this paper, aquatic plant leaves—including reed, water hyacinth, [...] Read more.

The biotemplating technique is an environmental-protective high-efficiency new technology by which the resulting TiO2 may simultaneously attain the duplication of structure and self-doping elements from biotemplate materials, which is highly desirable for photocatalytic applications. In this paper, aquatic plant leaves—including reed, water hyacinth, and duckweed—were used as both templates and silicon precursors to successfully synthesize biomorphic TiO2/SiO2 composite with mesoporous structures. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, N2 adsorption–desorption, and UV–visible diffuse reflectance spectra were applied to characterize the microstructures of the samples. The results show that all TiO2/SiO2 composites are mainly composed of an anatase phase with mesoporous structure and possess high specific surface area. Compared with commercial Degussa P25 TiO2, all TiO2/SiO2 samples display intensive light-harvesting efficiency, particularly in the visible light range. The activities were evaluated by using gentian violet as a target for photocatalytic degradation experiments under simulated solar irradiation. The TiO2/SiO2 samples templated by reed and water hyacinth leaves exhibit high activity, while the TiO2/SiO2 samples obtained from duckweed are inferior to P25 in the degradation of gentian violet. A synergistic effect of SiO2 incorporation and structural construction through biotemplating is proposed to be beneficial to photocatalytic activity. Full article

(This article belongs to the Special Issue Heterogeneous Catalysis for Environmental Remediation)

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18 pages, 2594 KiB

Open AccessArticle

Solvent-Free Biginelli Reactions Catalyzed by Hierarchical Zeolite Utilizing a Ball Mill Technique: A Green Sustainable Process

by Ameen Shahid¹, Nesreen S. Ahmed^2,3, Tamer S. Saleh^4,5,*

, Shaeel Ahmed Al-Thabaiti², Sulaiman N. Basahel², Wilhelm Schwieger¹ and Mohamed Mokhtar^2,6,*

¹ Institute of Chemical Reaction Technology, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058 Erlangen, Germany

² Department of Chemistry, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589, Saudi Arabia

³ Medicinal Chemistry Department, National Research Centre, El Buhouth St., Dokki, Cairo 12622, Egypt

⁴ Department of Chemistry, Faculty of Science, University of Jeddah, P.O. Box 80329, Jeddah 21589, Saudi Arabia

⁵ Green Chemistry Department, National Research Centre, Dokki, Cairo 12622, Egypt

⁶ Surface Chemistry and Catalysis Lab, Physical Chemistry Department, National Research Centre, El Buhouth St., Dokki, Cairo 12622, Egypt

Catalysts 2017, 7(3), 84; https://doi.org/10.3390/catal7030084 - 13 Mar 2017

Cited by 55 | Viewed by 9316

Abstract

A sustainable, green one-pot process for the synthesis of dihydropyrimidinones (DHPMs) derivatives by a three-component reaction of β-ketoester derivatives, aldehyde and urea or thiourea over the alkali-treated H-ZSM-5 zeolite under ball-milling was developed. Isolation of the product with ethyl acetate shadowed by vanishing [...] Read more.

A sustainable, green one-pot process for the synthesis of dihydropyrimidinones (DHPMs) derivatives by a three-component reaction of β-ketoester derivatives, aldehyde and urea or thiourea over the alkali-treated H-ZSM-5 zeolite under ball-milling was developed. Isolation of the product with ethyl acetate shadowed by vanishing of solvent was applied. The hierachical zeolite catalyst (MFI27_6) showed high yield (86%–96%) of DHPMs in a very short time (10–30 min). The recyclability of the catalyst for the subsequent reactions was examined in four subsequent runs. The catalyst was shown to be robust without a detectable reduction in catalytic activity, and high yields of products showed the efficient protocol of the Biginelli reactions. Full article

(This article belongs to the Special Issue Enabling Technologies toward Green Catalysis)

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26 pages, 4726 KiB

Open AccessArticle

Dendrimer-Stabilized Ru Nanoparticles Immobilized in Organo-Silica Materials for Hydrogenation of Phenols

by Eduard Karakhanov^1,*, Anton Maximov^1,2, Anna Zolotukhina¹, Adila Mamadli¹, Anna Vutolkina¹ and Andrey Ivanov²

¹ Department of Petroleum Chemistry and Organic Catalysis, Moscow State University, Moscow 119991, Russia

² A.V. Topchiev Institute of Petrochemical Synthesis, Russian Academy of Sciences, Moscow 119991, Russia

Catalysts 2017, 7(3), 86; https://doi.org/10.3390/catal7030086 - 14 Mar 2017

Cited by 32 | Viewed by 7943

Abstract

New hybrid catalysts based on Ru nanoparticles, encapsulated into poly(propylene imine dendrimers), immobilized into silica pores, were synthesized and examined for the hydrogenation of alkyl-substituted phenols. The corresponding alkyl-substituted cyclohexanols were presented as the major reaction products, while incomplete hydrogenation products appeared to [...] Read more.

New hybrid catalysts based on Ru nanoparticles, encapsulated into poly(propylene imine dendrimers), immobilized into silica pores, were synthesized and examined for the hydrogenation of alkyl-substituted phenols. The corresponding alkyl-substituted cyclohexanols were presented as the major reaction products, while incomplete hydrogenation products appeared to be minor. A competition between the sterical factors of dendrimer-containing carriers and the electronic factors of substrate substituents influenced the hydrogenation rate of the alkyl-substituted phenols. The carrier structure was found to have a significant influence on both the physical and chemical properties of the catalysts and their hydrogenation activity. The synthesized hybrid catalysts appeared to be stable after recycling and could be re-used several times without significant loss of activity. Full article

(This article belongs to the Special Issue Ruthenium Catalysts)

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13 pages, 3280 KiB

Open AccessArticle

The Role of Ruthenium in CO₂ Capture and Catalytic Conversion to Fuel by Dual Function Materials (DFM)

by Shuoxun Wang¹, Erik T. Schrunk², Harshit Mahajan² and And Robert J. Farrauto^1,*

¹ Earth and Environmental Engineering, Columbia University in the City of New York, New York 10027, NY, USA

² Chemical Engineering, Columbia University in the City of New York, New York 10027, NY, USA

Catalysts 2017, 7(3), 88; https://doi.org/10.3390/catal7030088 - 17 Mar 2017

Cited by 88 | Viewed by 12206

Abstract

Development of sustainable energy technologies and reduction of carbon dioxide in the atmosphere are the two effective strategies in dealing with current environmental issues. Herein we report a Dual Function Material (DFM) consisting of supported sodium carbonate in intimate contact with dispersed Ru [...] Read more.

Development of sustainable energy technologies and reduction of carbon dioxide in the atmosphere are the two effective strategies in dealing with current environmental issues. Herein we report a Dual Function Material (DFM) consisting of supported sodium carbonate in intimate contact with dispersed Ru as a promising catalytic solution for combining both approaches. The Ru-Na₂CO₃ DFM deposited on Al₂O₃ captures CO₂ from a flue gas and catalytically converts it to synthetic natural gas (i.e., methane) using H₂ generated from renewable sources. The Ru in the DFM, in combination with H₂, catalytically hydrogenates both adsorbed CO₂ and the bulk Na₂CO₃, forming methane. The depleted sites adsorb CO₂ through a carbonate reformation process and in addition adsorb CO₂ on its surface. This material functions well in O₂- and H₂O-containing flue gas where the favorable Ru redox property allows RuO_x, formed during flue gas exposure, to be reduced during the hydrogenation cycle. As a combined CO₂ capture and utilization scheme, this technology overcomes many of the limitations of the conventional liquid amine-based CO₂ sorbent technology. Full article

(This article belongs to the Special Issue Ruthenium Catalysts)

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11 pages, 2585 KiB

Open AccessArticle

Organocatalytic Enantioselective Epoxidation of Some Aryl-Substituted Vinylidenebisphosphonate Esters: On the Way to Chiral Anti-Osteoporosis Drugs

by Andrea Chiminazzo, Laura Sperni, Alessandro Scarso and Giorgio Strukul^*

Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca’ Foscari Venezia, via Torino 155, 30170 Venezia Mestre, Italy

Catalysts 2017, 7(3), 90; https://doi.org/10.3390/catal7030090 - 20 Mar 2017

Cited by 5 | Viewed by 5567

Abstract

The synthesis of a new class of epoxide derivatives from prochiral vinylidene bisphosphonate (VBP) precursors is reported using hydrogen peroxide as the terminal oxidant. The reaction is carried out using a series of possible organic activators having a basic character, with the best [...] Read more.

The synthesis of a new class of epoxide derivatives from prochiral vinylidene bisphosphonate (VBP) precursors is reported using hydrogen peroxide as the terminal oxidant. The reaction is carried out using a series of possible organic activators having a basic character, with the best results being observed using quinine and sparteine. These activators not only provide from good to excellent epoxide yields with a large variety of VBPs, but also interesting enantioselectivities in the 67%–96% ee range, at least in the case of the Ph and m-MeO–Ph VBP derivatives, opening the way to a number of chiral anti-osteoporosis potentially active pharmaceutical ingredients. Full article

(This article belongs to the Special Issue Activation of Dioxygen and Liquid Phase Oxidation Catalysis for Fine Chemistry)

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12 pages, 2811 KiB

Open AccessArticle

Stabilization of a Lipolytic Enzyme for Commercial Application

by Simone Antonio De Rose¹

, Halina Novak¹, Andrew Dowd²

, Sukriti Singh², Dietmar Andreas Lang² and Jennifer Littlechild^1,*

¹ Henry Wellcome Building for Biocatalysis, Biosciences, College of Life and Environmental Sciences, University of Exeter, Stocker Road, Exeter EX4 4QD, UK

² Unilever R&D, HomeCare Discover, Disruptive Biotechnology, Quarry Road East, Bebington CH63 3JW, UK

Catalysts 2017, 7(3), 91; https://doi.org/10.3390/catal7030091 - 21 Mar 2017

Cited by 11 | Viewed by 6487

Abstract

Thermomyces lanouginosa lipase has been used to develop improved methods for carrier-free immobilization, the Cross-Linked Enzyme Aggregates (CLEAs), for its application in detergent products. An activator step has been introduced to the CLEAs preparation process with the addition of Tween 80 as activator [...] Read more.

Thermomyces lanouginosa lipase has been used to develop improved methods for carrier-free immobilization, the Cross-Linked Enzyme Aggregates (CLEAs), for its application in detergent products. An activator step has been introduced to the CLEAs preparation process with the addition of Tween 80 as activator molecule, in order to obtain a higher number of the individual lipase molecules in the ”open lid” conformation prior to the cross-linking step. A terminator step has been introduced to quench the cross-linking reaction at an optimal time by treatment with an amine buffer in order to obtain smaller and more homogenous cross-linked particles. This improved immobilization method has been compared to a commercially available enzyme and has been shown to be made up of smaller and more homogenous particles with an average diameter of 1.85 ± 0.28 µm which are 129.7% more active than the free enzyme. The CLEAs produced show improved features for commercial applications such as an improved wash performance comparable with the free enzyme, improved stability to proteolysis and a higher activity after long-term storage. Full article

(This article belongs to the Special Issue Immobilized Enzymes: Strategies for Enzyme Stabilization)

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8 pages, 1486 KiB

Open AccessArticle

Catalytic Transfer Hydrogenation of Biobased HMF to 2,5-Bis-(Hydroxymethyl)Furan over Ru/Co₃O₄

by Ting Wang¹, Junhua Zhang^1,2,*, Wenxing Xie¹, Yanjun Tang^1,*, Daliang Guo^1,3 and Yonghao Ni^2,*

¹ Bioenergy & Biomass Centre, National Engineering Laboratory of Textile Materials Processing Technology, Zhejiang Sci-Tech. University, Hangzhou 310018, China

² Department of Chemical Engineering, University of New Brunswick, Fredericton, NB E3B 5A3, Canada

³ Key Laboratory of Pulp and Paper Science & Technology of Ministry of Education of China, Qilu University of Technology, Jinan 250353, China

Catalysts 2017, 7(3), 92; https://doi.org/10.3390/catal7030092 - 21 Mar 2017

Cited by 57 | Viewed by 10431

Abstract

2,5-Bis-(hydroxymethyl)furan (BHMF) is an important biomass-based platform chemical that can be derived from the hydrogenation of biomass-based 5-hydroxymethylfurfural (HMF). In this paper, the formation of BHMF from HMF via the catalytic transfer hydrogenation (CTH) process, using isopropanol as the hydrogen source and Ru/Co [...] Read more.

2,5-Bis-(hydroxymethyl)furan (BHMF) is an important biomass-based platform chemical that can be derived from the hydrogenation of biomass-based 5-hydroxymethylfurfural (HMF). In this paper, the formation of BHMF from HMF via the catalytic transfer hydrogenation (CTH) process, using isopropanol as the hydrogen source and Ru/Co₃O₄ as the catalyst, was studied. The results revealed that the Ru/Co₃O₄ catalyst displayed a high catalytic efficiency, and that a BHMF yield of up to 82% was obtained at 190 °C in 6 h. Moreover, it was found that the recovered Ru/Co₃O₄ exhibited a similar catalytic activity to the pristine Ru/Co₃O₄ catalyst. These results supported the conclusion that the present CTH process is an attractive green route for the synthesis of BHMF from biomass-based HMF. Full article

(This article belongs to the Special Issue Ruthenium Catalysts)

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16 pages, 5651 KiB

Open AccessArticle

Graphene Oxide-Supported Oxime Palladacycles as Efficient Catalysts for the Suzuki–Miyaura Cross-Coupling Reaction of Aryl Bromides at Room Temperature under Aqueous Conditions

by Melania Gómez-Martínez, Alejandro Baeza^*

and Diego A. Alonso^*

Departamento de Química Orgánica and Instituto de Síntesis Orgánica (ISO), Facultad de Ciencias, Universidad de Alicante. Apdo. 99, E-03080 Alicante, Spain

Catalysts 2017, 7(3), 94; https://doi.org/10.3390/catal7030094 - 22 Mar 2017

Cited by 21 | Viewed by 7016

Abstract

Palladacycles are highly efficient precatalysts in cross-coupling reactions whose immobilization on carbonaceous materials has been hardly studied. Herein, we report a detailed study on the synthesis and characterization of new oxime palladacycle-graphene oxide non-covalent materials along with their catalytic activity in the Suzuki–Miyaura [...] Read more.

Palladacycles are highly efficient precatalysts in cross-coupling reactions whose immobilization on carbonaceous materials has been hardly studied. Herein, we report a detailed study on the synthesis and characterization of new oxime palladacycle-graphene oxide non-covalent materials along with their catalytic activity in the Suzuki–Miyaura reaction. Catalyst 1-GO, which has been fully characterized by ICP, XPS, TGA, and UV-Vis analyses has been demonstrated to be an efficient catalyst for the Suzuki–Miyaura coupling between aryl bromides and arylboronic acids using very low catalyst loadings (0.002 mol % of Pd) at room temperature under aqueous conditions. Full article

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

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13 pages, 5225 KiB

Open AccessArticle

Highly Selective Solid Acid Catalyst H_1−xTi₂(PO₄)_3−x(SO₄)_x for Non-Oxidative Dehydrogenation of Methanol and Ethanol

by Gheorghiţa Mitran^1,*, Daniel G. Mieritz² and Dong-Kyun Seo^2,*

¹ Laboratory of Chemical Technology and Catalysis, Department of Organic Chemistry, Biochemistry & Catalysis, Faculty of Chemistry, University of Bucharest, 4-12, Blv. Regina Elisabeta, 030018 Bucharest, Romania

² School of Molecular Sciences, Arizona State University, Tempe, AZ 85287-1604, USA

Catalysts 2017, 7(3), 95; https://doi.org/10.3390/catal7030095 - 22 Mar 2017

Cited by 14 | Viewed by 5410

Abstract

The conversion of alcohols towards aldehydes in the presence of catalysts by non-oxidative dehydrogenation requires special importance from the perspective of green chemistry. Sodium (Na) super ionic conductor (NASICON)-type hydrogen titanium phosphate sulfate (HTPS; H_1−xTi₂(PO₄)₃₋ [...] Read more.

The conversion of alcohols towards aldehydes in the presence of catalysts by non-oxidative dehydrogenation requires special importance from the perspective of green chemistry. Sodium (Na) super ionic conductor (NASICON)-type hydrogen titanium phosphate sulfate (HTPS; H_1−xTi₂(PO₄)_3−x(SO₄)_x, x = 0.5–1) catalysts were synthesized by the sol-gel method, characterized by N₂ gas sorption, X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), NH₃ temperature-programmed desorption (NH₃-TPD), ultraviolet–visible (UV-VIS) spectroscopy, and their catalytic properties were studied for the non-oxidative dehydrogenation of methanol and ethanol. The ethanol is more reactive than methanol, with the conversion for ethanol exceeding 95% as compared to methanol, where the conversion has a maximum value at 55%. The selectivity to formaldehyde is almost 100% in methanol conversion, while the selectivity to acetaldehyde decreases from 56% to 43% in ethanol conversion, when the reaction temperature is increased from 250 to 400 °C. Full article

(This article belongs to the Special Issue C1 Chemistry—C1-Platform Chemicals as Cornerstone for a Sustainable Energy)

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Review

Jump to: Research, Other

32 pages, 3860 KiB

Open AccessReview

The Suzuki–Miyaura Cross-Coupling as a Versatile Tool for Peptide Diversification and Cyclization

by Tom Willemse^1,2, Wim Schepens³, Herman W. T. van Vlijmen³, Bert U. W. Maes² and Steven Ballet^1,*

¹ Research Group of Organic Chemistry, Departments of Bioengineering Sciences and Chemistry, Vrije Universiteit Brussel, 1050 Brussels, Belgium

² Organic Synthesis Division, University of Antwerp, 2020 Antwerp, Belgium

³ Discovery Sciences, Janssen Research and Development, 2340 Beerse, Belgium

Catalysts 2017, 7(3), 74; https://doi.org/10.3390/catal7030074 - 25 Feb 2017

Cited by 73 | Viewed by 18424

Abstract

The (site-selective) derivatization of amino acids and peptides represents an attractive field with potential applications in the establishment of structure–activity relationships and labeling of bioactive compounds. In this respect, bioorthogonal cross-coupling reactions provide valuable means for ready access to peptide analogues with diversified [...] Read more.

The (site-selective) derivatization of amino acids and peptides represents an attractive field with potential applications in the establishment of structure–activity relationships and labeling of bioactive compounds. In this respect, bioorthogonal cross-coupling reactions provide valuable means for ready access to peptide analogues with diversified structure and function. Due to the complex and chiral nature of peptides, mild reaction conditions are preferred; hence, a suitable cross-coupling reaction is required for the chemical modification of these challenging substrates. The Suzuki reaction, involving organoboron species, is appropriate given the stability and environmentally benign nature of these reactants and their amenability to be applied in (partial) aqueous reaction conditions, an expected requirement upon the derivatization of peptides. Concerning the halogenated reaction partner, residues bearing halogen moieties can either be introduced directly as halogenated amino acids during solid-phase peptide synthesis (SPPS) or genetically encoded into larger proteins. A reversed approach building in boron in the peptidic backbone is also possible. Furthermore, based on this complementarity, cyclic peptides can be prepared by halogenation, and borylation of two amino acid side chains present within the same peptidic substrate. Here, the Suzuki–Miyaura reaction is a tool to induce the desired cyclization. In this review, we discuss diverse amino acid and peptide-based applications explored by means of this extremely versatile cross-coupling reaction. With the advent of peptide-based drugs, versatile bioorthogonal conversions on these substrates have become highly valuable. Full article

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

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36 pages, 8456 KiB

Open AccessReview

Upgrading Lignocellulosic Biomasses: Hydrogenolysis of Platform Derived Molecules Promoted by Heterogeneous Pd-Fe Catalysts

by Claudia Espro¹

, Bianca Gumina¹

, Emilia Paone²

and Francesco Mauriello^2,*

¹ Dipartimento di Ingegneria, Università di Messina, Contrada di Dio Vill. S. Agata, I-98166 Messina, Italy

² Dipartimento DICEAM, Università Mediterranea di Reggio Calabria, Loc. Feo di Vito, I-89122 Reggio Calabria, Italy

Catalysts 2017, 7(3), 78; https://doi.org/10.3390/catal7030078 - 7 Mar 2017

Cited by 48 | Viewed by 11555

Abstract

This review provides an overview of heterogeneous bimetallic Pd-Fe catalysts in the C–C and C–O cleavage of platform molecules such as C2–C6 polyols, furfural, phenol derivatives and aromatic ethers that are all easily obtainable from renewable cellulose, hemicellulose and lignin (the major components [...] Read more.

This review provides an overview of heterogeneous bimetallic Pd-Fe catalysts in the C–C and C–O cleavage of platform molecules such as C2–C6 polyols, furfural, phenol derivatives and aromatic ethers that are all easily obtainable from renewable cellulose, hemicellulose and lignin (the major components of lignocellulosic biomasses). The interaction between palladium and iron affords bimetallic Pd-Fe sites (ensemble or alloy) that were found to be very active in several sustainable reactions including hydrogenolysis, catalytic transfer hydrogenolysis (CTH) and aqueous phase reforming (APR) that will be highlighted. This contribution concentrates also on the different synthetic strategies (incipient wetness impregnation, deposition-precipitaion, co-precipitaion) adopted for the preparation of heterogeneous Pd-Fe systems as well as on the main characterization techniques used (XRD, TEM, H₂-TPR, XPS and EXAFS) in order to elucidate the key factors that influence the unique catalytic performances observed. Full article

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34 pages, 3767 KiB

Open AccessReview

Electrocatalysts Prepared by Galvanic Replacement

by Athanasios Papaderakis¹, Ioanna Mintsouli¹, Jenia Georgieva² and Sotiris Sotiropoulos^1,*

¹ Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece

² Rostislaw Kaischew Institute of Physical Chemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria

Catalysts 2017, 7(3), 80; https://doi.org/10.3390/catal7030080 - 8 Mar 2017

Cited by 119 | Viewed by 17880

Abstract

Galvanic replacement is the spontaneous replacement of surface layers of a metal, M, by a more noble metal, M_noble, when the former is treated with a solution containing the latter in ionic form, according to the general replacement reaction: nM [...] Read more.

Galvanic replacement is the spontaneous replacement of surface layers of a metal, M, by a more noble metal, M_noble, when the former is treated with a solution containing the latter in ionic form, according to the general replacement reaction: nM + mM_nobleⁿ⁺ → nM^m⁺ + mM_noble. The reaction is driven by the difference in the equilibrium potential of the two metal/metal ion redox couples and, to avoid parasitic cathodic processes such as oxygen reduction and (in some cases) hydrogen evolution too, both oxygen levels and the pH must be optimized. The resulting bimetallic material can in principle have a M_noble-rich shell and M-rich core (denoted as M_noble(M)) leading to a possible decrease in noble metal loading and the modification of its properties by the underlying metal M. This paper reviews a number of bimetallic or ternary electrocatalytic materials prepared by galvanic replacement for fuel cell, electrolysis and electrosynthesis reactions. These include oxygen reduction, methanol, formic acid and ethanol oxidation, hydrogen evolution and oxidation, oxygen evolution, borohydride oxidation, and halide reduction. Methods for depositing the precursor metal M on the support material (electrodeposition, electroless deposition, photodeposition) as well as the various options for the support are also reviewed. Full article

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25 pages, 859 KiB

Open AccessFeature PaperReview

Review of Heterogeneous Catalysts for Catalytically Upgrading Vegetable Oils into Hydrocarbon Biofuels

by Xianhui Zhao^1,2, Lin Wei^1,*, Shouyun Cheng¹

and James Julson¹

¹ Department of Agricultural & Biosystems Engineering, South Dakota State University, Brookings, SD 57007, USA

² Department of Chemical & Biomedical Engineering, University of South Florida, Tampa, FL 33620, USA

Catalysts 2017, 7(3), 83; https://doi.org/10.3390/catal7030083 - 11 Mar 2017

Cited by 99 | Viewed by 16136

Abstract

To address the issues of greenhouse gas emissions associated with fossil fuels, vegetable oilseeds, especially non-food oilseeds, are used as an alternative fuel resource. Vegetable oil derived from these oilseeds can be upgraded into hydrocarbon biofuel. Catalytic cracking and hydroprocessing are two of [...] Read more.

To address the issues of greenhouse gas emissions associated with fossil fuels, vegetable oilseeds, especially non-food oilseeds, are used as an alternative fuel resource. Vegetable oil derived from these oilseeds can be upgraded into hydrocarbon biofuel. Catalytic cracking and hydroprocessing are two of the most promising pathways for converting vegetable oil to hydrocarbon biofuel. Heterogeneous catalysts play a critical role in those processes. The present review summarizes current progresses and remaining challenges of vegetable oil upgrading to biofuel. The catalyst properties, applications, deactivation, and regeneration are reviewed. A comparison of catalysts used in vegetable oil and bio-oil upgrading is also carried out. Some suggestions for heterogeneous catalysts applied in vegetable oil upgrading to improve the yield and quality of hydrocarbon biofuel are provided for further research in the future. Full article

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38 pages, 13877 KiB

Open AccessReview

Recent Advancements in Stereoselective Olefin Metathesis Using Ruthenium Catalysts

by T. Patrick Montgomery, Adam M. Johns and Robert H. Grubbs^*

The Arnold and Mabel Beckman Laboratory of Chemical Synthesis, Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA

Catalysts 2017, 7(3), 87; https://doi.org/10.3390/catal7030087 - 14 Mar 2017

Cited by 109 | Viewed by 15214

Abstract

Olefin metathesis is a prevailing method for the construction of organic molecules. Recent advancements in olefin metathesis have focused on stereoselective transformations. Ruthenium olefin metathesis catalysts have had a particularly pronounced impact in the area of stereoselective olefin metathesis. The development of three [...] Read more.

Olefin metathesis is a prevailing method for the construction of organic molecules. Recent advancements in olefin metathesis have focused on stereoselective transformations. Ruthenium olefin metathesis catalysts have had a particularly pronounced impact in the area of stereoselective olefin metathesis. The development of three categories of Z-selective olefin metathesis catalysts has made Z-olefins easily accessible to both laboratory and industrial chemists. Further design enhancements to asymmetric olefin metathesis catalysts have streamlined the construction of complex molecules. The understanding gained in these areas has extended to the employment of ruthenium catalysts to stereoretentive olefin metathesis, the first example of a kinetically E-selective process. These advancements, as well as synthetic applications of the newly developed catalysts, are discussed. Full article

(This article belongs to the Special Issue Ruthenium Catalysts)

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27 pages, 7214 KiB

Open AccessReview

Pd/C Catalysis under Microwave Dielectric Heating

by Elena Cini¹, Elena Petricci²

and Maurizio Taddei^2,*

¹ Lead Discovery Siena, Strada del Petriccio e Belriguardo 35, 53100 Siena, Italy

² Dipartimento di Biotecnologie Chimica e Farmacia, Università degli Studi di Siena, via A. Moro 2, 53100 Siena, Italy

Catalysts 2017, 7(3), 89; https://doi.org/10.3390/catal7030089 - 20 Mar 2017

Cited by 24 | Viewed by 15225

Abstract

Microwave-assisted organic synthesis (MAOS) provides a novel and efficient means of achieving heat organic reactions. Nevertheless, the potential arcing phenomena via microwave (MW) interaction with solid metal catalysts has limited its use by organic chemists. As arcing phenomena are now better understood, new [...] Read more.

Microwave-assisted organic synthesis (MAOS) provides a novel and efficient means of achieving heat organic reactions. Nevertheless, the potential arcing phenomena via microwave (MW) interaction with solid metal catalysts has limited its use by organic chemists. As arcing phenomena are now better understood, new applications of Pd/C-catalyzed reactions under MW dielectric heating are now possible. In this review, the state of the art, benefits, and challenges of coupling MW heating with heterogeneous Pd/C catalysis are discussed to inform organic chemists about their use with one of the most popular heterogeneous catalysts. Full article

(This article belongs to the Special Issue Enabling Technologies toward Green Catalysis)

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14 pages, 239 KiB

Open AccessReview

Photocatalytic Water Oxidation on ZnO: A Review

by Sharifah Bee Abdul Hamid^*, Swe Jyan Teh

and Chin Wei Lai

Nanotechnology and Catalysis Research Centre, Institute of Graduate Studies, University of Malaya, 50603 Kuala Lumpur, Malaysia

Catalysts 2017, 7(3), 93; https://doi.org/10.3390/catal7030093 - 21 Mar 2017

Cited by 147 | Viewed by 11832

Abstract

The investigation of the water oxidation mechanism on photocatalytic semiconductor surfaces has gained much attention for its potential to unlock the technological limitations of producing H₂ from carbon-free sources, i.e., H₂O. This review seeks to highlight the available scientific and [...] Read more.

The investigation of the water oxidation mechanism on photocatalytic semiconductor surfaces has gained much attention for its potential to unlock the technological limitations of producing H₂ from carbon-free sources, i.e., H₂O. This review seeks to highlight the available scientific and fundamental understanding towards the water oxidation mechanism on ZnO surfaces, as well as present a summary on the modification strategies carried out to increase the photocatalytic response of ZnO. Full article

(This article belongs to the Special Issue Water Oxidation Catalysis)

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12 pages, 1838 KiB

Open AccessLetter

Olefin Metathesis with Ru-Based Catalysts Exchanging the Typical N-Heterocyclic Carbenes by a Phosphine–Phosphonium Ylide

by Laia Arnedo¹, Remi Chauvin^2,3,* and Albert Poater^2,*

¹ Institut de Química Computacional i Catàlisi and Departament de Química, Universitat de Girona, Campus Montilivi, 17003 Girona, Catalonia, Spain

² CNRS, LCC (Laboratoire de Chimie de Coordination), 205 Route de Narbonne, BP44099, 31077 Toulouse CEDEX 4, France

³ Université de Toulouse, UPS, ICT-FR 2599, 31062 Toulouse CEDEX 9, France

Catalysts 2017, 7(3), 85; https://doi.org/10.3390/catal7030085 - 14 Mar 2017

Cited by 6 | Viewed by 6210

Abstract

Density functional theory (DFT) calculations have been used to describe the first turnover of an olefin metathesis reaction calling for a new in silico family of homogenous Ru-based catalysts bearing a phosphine–phosphonium ylide ligand, with ethylene as a substrate. Equal to conventional Ru-based [...] Read more.

Density functional theory (DFT) calculations have been used to describe the first turnover of an olefin metathesis reaction calling for a new in silico family of homogenous Ru-based catalysts bearing a phosphine–phosphonium ylide ligand, with ethylene as a substrate. Equal to conventional Ru-based catalysts bearing an N-heterocyclic carbene (NHC) ligand, the activation of these congeners occurs through a dissociative mechanism, with a more exothermic first phosphine dissociation step. In spite of a stronger electron-donating ability of a phosphonium ylide C-ligand with respect to a diaminocarbene analogue, upper energy barriers were calculated to be on average ca. 5 kcal/mol higher than those of Ru–NHC standards. Overall, the study also highlights advantages of bidentate ligands over classical monodentate NHC and phosphine ligands, with a particular preference for the cis attack of the olefin. The new generation of catalysts is constituted by cationic complexes potentially soluble in water, to be compared with the typical neutral Ru–NHC ones. Full article

(This article belongs to the Special Issue Ruthenium Catalysts)

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