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Kegong Fang - One of the best experts on this subject based on the ideXlab platform.
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preparation structural characteristics and catalytic performance of cu co alloy supported on mn al oxide for higher alcohol synthesis via syngas
Industrial & Engineering Chemistry Research, 2018Co-Authors: Lu Zhao, Jiani Duan, Qiulan Zhang, Kegong FangAbstract:A series of Mn–Al oxide supported Cu–Co alloy catalysts having various molar ratios of Cu/Co were prepared using the facile sol–gel synthesis, with the aim of investigating the effects of the chemical, physical properties in the catalytic behavior on higher alcohol synthesis (HAS). The as-prepared samples were characterized through utilizing XRD, BET, TEM, XPS, H2-TPD/TPR, CO-TPD, in-situ CO adsorption DRIFTS, and CO-TPSR techniques. The study suggests that the proper ratio of Cu/Co could adjust the amount of adsorbed hydrogen and nondissociatively adsorbed CO at the surface of catalyst on CO hydrogenation and insertion, improve the reducibility, and ameliorate the catalytic behavior for HAS. Especially, the 3Cu–5Co/(Mn–Al) catalyst showed the best catalytic behavior with a CO conversion of 33.4%, total alcohol selectivity of 39.7%, C2+ alcohol selectivity in the total alcohols of 57.3% at GHSV of 5000 h–1, 260 °C, and 5 MPa.
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a novel catalyst for higher alcohol synthesis from syngas co zn supported on mn al oxide
Fuel Processing Technology, 2018Co-Authors: Lu Zhao, Kegong FangAbstract:Abstract A series of the Co Zn catalysts supported on Mn Al oxide with different Co/Zn molar ratios were synthesized according to the sol–gel method and used for higher alcohol synthesis from syngas. The chemical and physical properties of the as-synthesized catalysts were investigated by various characterization methods such as XRD, H2-TPR, N2 adsorption and desorption, CO2-TPD, CO-TPD, DRIFTS, H2-TPD, TEM, XPS, and CO-TPSR. The results indicated that CO conversion and alcohol selectivity changed depending upon the Co/Zn molar ratio that significantly influenced the properties of the as-synthesized catalysts. The proper Co/Zn molar ratio can increase the concentration of moderate/strong basic sites, improve the amount of non-dissociated CO on the catalyst surface for CO insertion, and enhance the catalytic performance for higher alcohol synthesis. In particular, the 4Co 4Zn catalyst shows the highest selectivity to higher alcohols (80%) among all the catalysts.
Lu Zhao - One of the best experts on this subject based on the ideXlab platform.
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preparation structural characteristics and catalytic performance of cu co alloy supported on mn al oxide for higher alcohol synthesis via syngas
Industrial & Engineering Chemistry Research, 2018Co-Authors: Lu Zhao, Jiani Duan, Qiulan Zhang, Kegong FangAbstract:A series of Mn–Al oxide supported Cu–Co alloy catalysts having various molar ratios of Cu/Co were prepared using the facile sol–gel synthesis, with the aim of investigating the effects of the chemical, physical properties in the catalytic behavior on higher alcohol synthesis (HAS). The as-prepared samples were characterized through utilizing XRD, BET, TEM, XPS, H2-TPD/TPR, CO-TPD, in-situ CO adsorption DRIFTS, and CO-TPSR techniques. The study suggests that the proper ratio of Cu/Co could adjust the amount of adsorbed hydrogen and nondissociatively adsorbed CO at the surface of catalyst on CO hydrogenation and insertion, improve the reducibility, and ameliorate the catalytic behavior for HAS. Especially, the 3Cu–5Co/(Mn–Al) catalyst showed the best catalytic behavior with a CO conversion of 33.4%, total alcohol selectivity of 39.7%, C2+ alcohol selectivity in the total alcohols of 57.3% at GHSV of 5000 h–1, 260 °C, and 5 MPa.
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a novel catalyst for higher alcohol synthesis from syngas co zn supported on mn al oxide
Fuel Processing Technology, 2018Co-Authors: Lu Zhao, Kegong FangAbstract:Abstract A series of the Co Zn catalysts supported on Mn Al oxide with different Co/Zn molar ratios were synthesized according to the sol–gel method and used for higher alcohol synthesis from syngas. The chemical and physical properties of the as-synthesized catalysts were investigated by various characterization methods such as XRD, H2-TPR, N2 adsorption and desorption, CO2-TPD, CO-TPD, DRIFTS, H2-TPD, TEM, XPS, and CO-TPSR. The results indicated that CO conversion and alcohol selectivity changed depending upon the Co/Zn molar ratio that significantly influenced the properties of the as-synthesized catalysts. The proper Co/Zn molar ratio can increase the concentration of moderate/strong basic sites, improve the amount of non-dissociated CO on the catalyst surface for CO insertion, and enhance the catalytic performance for higher alcohol synthesis. In particular, the 4Co 4Zn catalyst shows the highest selectivity to higher alcohols (80%) among all the catalysts.
Kyu Wan Lee - One of the best experts on this subject based on the ideXlab platform.
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Fischer-Tropsch Synthesis by Carbon Dioxide Hydrogenation on Fe-Based Catalysts
Catalysis Surveys from Asia, 2008Co-Authors: P.s. Sai Prasad, Ki-won Jun, Kyu Wan Lee, Jong Wook BaeAbstract:Impregnated and co-precipitated, promoted and unpromoted, bulk and supported iron catalysts were prepared, characterized, and subjected to hydrogenation of CO2 at various pressures (1–2 MPa) and temperatures (573–673 K). Potassium, as an important promoter, enhanced the CO2 uptake and selectivity towards olefins and long-chain hydrocarbons. Al2O3, when added as a structural promoter during co-precipitation, increased CO2 conversion as well as selectivity to C2+ hydrocarbons. Among V, Cr, Mn and Zn promoters, Zn offered the highest selectivity to C2–C4 alkenes. The different episodes involved in the transformation of the catalyst before it reached steady-state were identified, on the co-precipitated catalyst. Using a biomass derived syngas (CO/CO2/H2), CO alone took part in hydrogenation. When enriched with H2, CO2 was also converted to hydrocarbons. The deactivation of impregnated Fe–K/Al2O3 catalyst was found to be due to carbon deposition, whereas that for the precipitated catalyst was due to increase in crystallinity of iron species. The suitability of SiO2, TiO2, Al2O3, HY and ion exchanged NaY as supports was examined for obtaining high activity and selectivity towards light olefins and C2+ hydrocarbons and found Al2O3 to be the best support. A comparative study with Co catalysts revealed the advantages of Fe catalysts for hydrocarbon production by F–T synthesis.
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comparative study of fischer tropsch synthesis with h2 co and h2 co2 syngas using fe and co based catalysts
Applied Catalysis A-general, 1999Co-Authors: Thomas Riedel, Ki-won Jun, Michael Claeys, Hans Schulz, Georg Schaub, Sangsung Nam, Myoungjae Choi, Gurram Kishan, Kyu Wan LeeAbstract:Hydrogenation of CO, CO2 and their mixtures has been comparatively studied with a Co–MnO–Aerosil–Pt and a Fe–Al2O3–Cu–K catalyst at the University of Karlsruhe. With iron catalysts as promising for CO2 hydrogenation, their composition was varied: (1) several supports (SiO2, TiO2, Al2O3), (2) alkali promotion (Li, Na, K, Rb), (3) usage of Zeolite Y as catalyst component. The catalysts were characterised by adsorption methods, XRD, TPR and temperature programmed decarburisation after a H2/CO2 treatment (Korea Research Institute of Chemical Technology). Iron and cobalt catalysts behaved differently in CO2 hydrogenation. With the alkalised iron catalyst the same hydrocarbon product composition was obtained from a H2/CO2 and from a H2/CO synthesis gas in spite of the CO partial pressure remaining low, specifically due to water gas shift equilibrium constraints. With the cobalt catalyst at increasing CO2 and respectively decreasing CO content of the syngas, the product composition shifted from a Fischer–Tropsch type (mainly higher hydrocarbons) to almost exclusively methane. These basically different catalyst behaviours are explained by different modes of formation of the kinetic regime of FT synthesis—selective inhibition of methane formation and the selective inhibition of product desorption as a prerequisite for chain growth—in the case of iron through irreversible carbiding and alkali surface coverage and in case of cobalt through strong reversible CO adsorption. Investigation of the various modified iron catalysts showed alumina to be the best support for CO2 hydrogenation and potassium to act as a powerful promotor. With the Fe–Y–zeolite–alkali catalysts, a decrease of methane selectivity was observed in the order Li < Na < K < Rb being applied as promotors.
Jiling Huang - One of the best experts on this subject based on the ideXlab platform.
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ethylene polymerization with long lifetime monopendant thienyl substituted group 4 metallocenes thienyl substituted group 4 metallocenes for ethylene polymerization
Applied Organometallic Chemistry, 2014Co-Authors: Wei Xiao, Jiling HuangAbstract:A series of group 4 metallocenes (RCp)[Cp―(bridge)―(2-C4H3S)]MCl2 [M = Ti (C1, C2, C3, C4); M = Zr (C5, C6, C7, C8)] bearing a pendant thiophene group on a cyclopentadienyl ring have been synthesized, characterized and tested as catalyst precursors for ethylene polymerization. The molecular structures of representative titanocenes C2 and C4 were confirmed by single-crystal X-ray diffraction and revealed that both complexes exist in an expected coordination environment for a monomeric bent metallocene. No intramolecular coordination between the thiophene group and the titanium center could be observed in the solid state. Upon activation by methylaluminoxane (MAO), titanocenes C1, C2, C3, C4 showed moderate catalytic activities and produced high- or ultra-high-molecular-weight polyethylene (Mv 70.5–227.1 × 104 g mol−1). Titanocene C3 is more active and long-lived, with a lifetime of nearly 9 h at 30 °C. At elevated temperatures of 80–110 °C, zirconocenes C5, C6, C7, C8 displayed high catalytic activities (up to 27.6 × 105 g PE (mol Zr)−1 h−1), giving high-molecular-weight polyethylene (Mv 11.2–53.7 × 104 g mol−1). Even at 80 °C, a long lifetime of at least 2 h was observed for the C8/MAO catalyst system. Copyright © 2014 John Wiley & Sons, Ltd.
Christopher W Jones - One of the best experts on this subject based on the ideXlab platform.
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vapor phase hydrogenation of furfural over nickel mixed metal oxide catalysts derived from layered double hydroxides
Applied Catalysis A-general, 2016Co-Authors: Taylor P Sulmonetti, Simon H Pang, Micaela Taborga Claure, David A Cullen, Pradeep K Agrawal, Christopher W JonesAbstract:Abstract The hydrogenation of furfural is investigated over various reduced nickel mixed metal oxides derived from layered double hydroxides (LDHs) containing Ni-Mg-Al and Ni-Co-Al. Upon reduction, relatively large Ni(0) domains develop in the Ni-Mg-Al catalysts, whereas in the Ni-Co-Al catalysts smaller metal particles of Ni(0) and Co(0), potentially as alloys, are formed, as evidenced by XAS, XPS, STEM and EELS. All the reduced Ni catalysts display similar selectivities towards major hydrogenation products (furfuryl alcohol and tetrahydrofurfuryl alcohol), though the side products varied with the catalyst composition. The 1.1Ni-0.8Co-Al catalyst showed the greatest activity per titrated site when compared to the other catalysts, with promising activity compared to related catalysts in the literature. The use of base metal catalysts for hydrogenation of furanic compounds may be a promising alternative to the well-studied precious metal catalysts for making biomass-derived chemicals if catalyst selectivity can be improved in future work by alloying or tuning metal-oxide support interactions
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on the stability and recyclability of supported metal ligand complex catalysts myths misconceptions and critical research needs
Topics in Catalysis, 2010Co-Authors: Christopher W JonesAbstract:Research on heterogenized metal complex catalysts has been carried out for 40 years. Despite thousands of published catalysts, there are only two significant commercial processes that utilize supported metal complex catalysts. Most academic papers are simply “demonstration of concept” studies reporting myriad ways to support various metal complex catalysts. Too few papers focus on rigorous studies of reaction kinetics, catalyst recycle, catalyst stability and deactivation pathways. Here, preliminary stability and deactivation studies of supported enantioselective Co-salen epoxide ring-opening catalysts and enantioselective Ru-salen olefin cyclopropanation catalysts are summarized. Insights with regard to catalyst deactivation suggest methodologies for catalyst stabilization, allowing for more effective catalyst recycle and enhanced catalyst turnover. Further examples where supported metal complex catalysts are applied in commercial processes will require the field to shift focus from “demonstration of concept” studies to more detailed investigations of catalyst stability and recyclability.
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magnetic nanoparticle polymer brush catalysts alternative hybrid organic inorganic structures to obtain high local catalyst loadings for use in organic transformations
Catalysis Letters, 2009Co-Authors: Christopher S Gill, Wei Long, Christopher W JonesAbstract:A new class of hybrid organic/inorganic molecular catalysts with high, local catalyst concentrations is demonstrated by supporting organic and organometallic catalysts on magnetic nanoparticle based polymer brushes (MPB). Poly(styrene) brushes containing Co(III)-salen or piperazine side chains are prepared via atom-transfer radical polymerization (ATRP) from Fe3O4 nanoparticles modified with appropriate initiator molecules. The polymer brush architecture promotes the cooperative interactions required for Co-salen catalyzed ring-opening of epoxides as demonstrated in the hydrolytic kinetic resolution of rac-epichlorohydrin. In addition, the piperazine functionalized MPB catalyst contains the high catalyst concentration that is required for promoting the Knoevenagel condensation of benzaldehyde and malononitrile with this type of amine catalyst. All the MPB catalysts were easily removed from solution via application of a magnetic field, allowing straightforward recovery and reuse. The versatile MPB architecture can be used to create a variety of recoverable supported organic or organometallic catalysts.
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engineering polymer enhanced bimetallic cooperative interactions in the hydrolytic kinetic resolution of epoxides
Advanced Synthesis & Catalysis, 2008Co-Authors: Xiaolai Zheng, Christopher W Jones, Marcus WeckAbstract:Through systematic variations of the length of oligo(ethylene glycol)-based linkers and the catalyst density of poly(styrene)-supported cobalt-salen catalysts, we have elucidated an optimal catalyst flexibility and density of polymeric Co-salen catalysts for the hydrolytic kinetic resolution (HKR) of racemic terminal epoxides that follows a bimetallic cooperative pathway. The optimized polymeric catalyst brings the two cooperative Co-salen units to a favorable proximity efficiently and hence displays significantly improved catalytic performance in the HKR compared with its monomeric small molecule analogue. Complex Co(5b), representing the most active poly(styrene)-supported HKR catalyst known so far, can effect the resolution of a variety of epoxides to reach ≥98 % ee in 6–24 h with a low cobalt loading of 0.01–0.1 mol %.