The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform
Kaoru Fujimoto - One of the best experts on this subject based on the ideXlab platform.
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Supercritical Phase Fischer-Tropsch Synthesis Reaction
Studies in Surface Science and Catalysis, 2008Co-Authors: Kohshiroh Yokota, Yoshio Hanakata, Kaoru FujimotoAbstract:Summary Characteristic features of Fischer-Tropsch Synthesis reaction which was operated in the supercritical n-hexane media were summarized in three points, (1) quick diffusion of reactants (2) effective removal of reaction heat and (3) effective wax extraction, α-olefins and water, which was the primary product and by-product of F-T Synthesis, extracted from the catalyst bed most effectively in the supercritical phase reaction to suppress its secondary hydrogenation to paraffins. Extraction capability of the fluid was intensively studied and was found to be defined as the conbination of desorption from the catalyst surface and diffusion inside the catalyst pores.
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Three-component hybrid catalyst for direct Synthesis of isoparaffin via modified Fischer–Tropsch Synthesis
Catalysis Communications, 2003Co-Authors: Noritatsu Tsubaki, Yoshiharu Yoneyama, Keisuke Michiki, Kaoru FujimotoAbstract:Abstract Direct isoparaffin Synthesis method from syngas was developed by using a hybrid catalyst composed of Fischer–Tropsch Synthesis catalyst, ZSM-5 zeolite, and Pd/SiO2, where normal paraffin from Fischer–Tropsch Synthesis was hydrocracked in situ on ZSM-5 and Pd/SiO2 stabilized zeolite activity effectively even at pressurized steam atmosphere mainly via spillover effect.
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Hybrid Catalyst for Direct Synthesis of Isoparaffin through Modified Fischer-Tropsch Synthesis
Journal of The Japan Petroleum Institute, 2001Co-Authors: Noritatsu Tsubaki, Yoshiharu Yoneyama, Keisuke Michiki, Kaoru FujimotoAbstract:Direct isoparaffin Synthesis method from syngas was developed by using a hybrid catalyst composed of Fischer-Tropsch Synthesis catalyst and ZSM-5 zeolite. Normal paraffin were synthesized on Fischer-Tropsch Synthesis catalyst and consecutively hydrocracked on the coexisting zeolite, to form lighter branched hydrocarbon in the same reactor A third component, Pd/SiO2, was added to the hybrid catalyst and it stabilized the catalyst system effectively. It seems that Pd/SiO2 initiated spillover effect to stabilize zeolite activity even if water existed.
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Supercritical phase Fischer-Tropsch Synthesis reaction
Fuel, 1991Co-Authors: Kohshiroh Yokota, Kaoru FujimotoAbstract:Abstract A Fischer-Tropsch Synthesis reaction was conducted in a supercritical fluid medium using a fixed bed reactor. Although the rate of reaction and the diffusion of reactants and products were slightly lower than those in the gas phase reaction, the removal of reaction heat and waxy product from the catalyst surface were much more effective than those in the gas phase reaction. The supercritical phase reaction produced more higher carbon compounds (> C 25 ) than reactions in either liquid or gas phase.
A. Sayari - One of the best experts on this subject based on the ideXlab platform.
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Sulfated Zirconia as a Cocatalyst in Fischer−Tropsch Synthesis
Energy & Fuels, 1996Co-Authors: Xuemin Song And, A. SayariAbstract:This work deals with the direct Synthesis of branched hydrocarbons from Synthesis gas using a two-component catalyst: a Fischer−Tropsch Synthesis catalyst (RuKY) and a sulfated zirconia (SO42-/ZrO2) strong acid catalyst. The composition of C7 hydrocarbons was used to gauge the effect of the acid catalyst on hydrocarbon product selectivity. Over RuKY alone, C7 olefins prevail in C7 hydrocarbons while the content of branched C7 paraffins is very low. The use of SO42-/ZrO2 as a cocatalyst for Fischer−Tropsch Synthesis causes significant changes in the composition of hydrocarbon products, particularly in the early stages of the reaction. It increases the content of branched paraffins and decreases that of olefins. However, this catalyst suffers serious deactivation. Addition of small amounts of Pt to SO42-/ZrO2 is an effective way for stabilizing its activity under FTS reaction conditions. CO in the Synthesis gas has a suppressing effect on the catalytic activity of SO42-/ZrO2 catalysts. This effect becomes ...
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Sulfated zirconia as a co-catalyst in Fischer-Tropsch Synthesis
1995Co-Authors: Xuemin Song, A. SayariAbstract:This report describes studies of Fischer-Tropsch Synthesis utilizing sulfated zirconia and platinum sulfates as catalysts.
E. Van Steen - One of the best experts on this subject based on the ideXlab platform.
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Thermodynamic and experimental aspects of ‘supercritical’ Fischer–Tropsch Synthesis
Fuel Processing Technology, 2010Co-Authors: L.d. Biquiza, Michael Claeys, E. Van SteenAbstract:Abstract The addition of a hydrocarbon, n -hexane, to the feed of the iron-catalyzed Fischer–Tropsch Synthesis in a fixed bed reactor operating at a total pressure of 60 or 90 bar is shown to be beneficial, i.e. resulting in a higher activity with only a slight increase in methane selectivity. The thermodynamic properties of pseudo-binary systems containing H 2 :CO: n -hexane (2:1: y )–long chain hydrocarbon were investigated using the Peng–Robinson equation of state. The chain length of the long chain hydrocarbon is systematically varied to investigate the thermodynamic behaviour of the system in real waxes. It is concluded that supercritical conditions require pressures in excess of those applied in this study (and those reported in the literature). Thus, a supercritical phase is not formed. It is further shown that a three-phase system is likely to be present in the reactor under the typically applied reaction condition for the so-called ‘supercritical’ Fischer–Tropsch Synthesis. The reported beneficial effect of the added hydrocarbon to the feed of the Fischer–Tropsch Synthesis might be attributed to the change in the partial pressure of the reactants, hydrogen and carbon monoxide. The addition of a hydrocarbon can further aid in obtaining primary products of the Fischer–Tropsch Synthesis due to increase in the liquid flow rate through the reactor.
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Does mono-atomic Ru catalyse the Fischer-Tropsch Synthesis?
Studies in Surface Science and Catalysis, 2007Co-Authors: Michael Claeys, M. Hearshaw, John R. Moss, E. Van SteenAbstract:Abstract The Fischer-Tropsch Synthesis was studied using a Ru-dendrimer (Rp3G1C) supported on silica as a catalyst. The stability of the Ru-dendrimer catalyst was investigated using TGA in nitrogen, hydrogen, carbon monoxide and a hydrogen/carbon monoxide atmosphere. Under typical Fischer-Tropsch conditions the catalyst is meta-stable. The time-on-stream behaviour of this catalyst in the CO hydrogenation was compared with an impregnated Ru/SiO 2 catalyst and showed no FT-specific product patterns. This seems to indicate that a single metallic site is not sufficient for the Fischer-Tropsch Synthesis. This is substantiated by the rate of formation of some specific hydrocarbons.
Kohshiroh Yokota - One of the best experts on this subject based on the ideXlab platform.
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Supercritical Phase Fischer-Tropsch Synthesis Reaction
Studies in Surface Science and Catalysis, 2008Co-Authors: Kohshiroh Yokota, Yoshio Hanakata, Kaoru FujimotoAbstract:Summary Characteristic features of Fischer-Tropsch Synthesis reaction which was operated in the supercritical n-hexane media were summarized in three points, (1) quick diffusion of reactants (2) effective removal of reaction heat and (3) effective wax extraction, α-olefins and water, which was the primary product and by-product of F-T Synthesis, extracted from the catalyst bed most effectively in the supercritical phase reaction to suppress its secondary hydrogenation to paraffins. Extraction capability of the fluid was intensively studied and was found to be defined as the conbination of desorption from the catalyst surface and diffusion inside the catalyst pores.
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Supercritical phase Fischer-Tropsch Synthesis reaction
Fuel, 1991Co-Authors: Kohshiroh Yokota, Kaoru FujimotoAbstract:Abstract A Fischer-Tropsch Synthesis reaction was conducted in a supercritical fluid medium using a fixed bed reactor. Although the rate of reaction and the diffusion of reactants and products were slightly lower than those in the gas phase reaction, the removal of reaction heat and waxy product from the catalyst surface were much more effective than those in the gas phase reaction. The supercritical phase reaction produced more higher carbon compounds (> C 25 ) than reactions in either liquid or gas phase.
J. Van De Loosdrecht - One of the best experts on this subject based on the ideXlab platform.
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Fischer-Tropsch Synthesis : catalysts and chemistry
Comprehensive Inorganic Chemistry II, 2013Co-Authors: J. Van De Loosdrecht, F.g. Botes, Im Ionel Ciobica, Alta C. Ferreira, Philip Gibson, D.j. Moodley, A.m. Saib, Visagie Jacobus Lucas, C.j. Weststrate, J.w. NiemantsverdrietAbstract:The Fischer–Tropsch Synthesis represents a time-tested and fully proven technology for the conversion of Synthesis gas (CO + H 2 ) into paraffins, olefins, and oxygenated hydrocarbons. Depending on the origin of the syngas, one speaks of gas-to-liquids, coal-to-liquids, biomass-to-liquids, or ‘anything’-to-liquids. Industrial Fischer–Tropsch plants run on iron or cobalt catalysts, in fixed-bed-, fluidized-bed-, or slurry bubble-column-type reactors. The Fischer–Tropsch Synthesis has inspired a wealth of academic and industrial research, and questions as to the mechanism of the process, how to control the selectivity of the polymerization process, the surface structure of the active catalysts, and the reasons why the catalysts deactivate continue to be subjects of intense discussion at conferences and in the literature. This chapter presents an overview of the Fischer–Tropsch Synthesis, its historical development, the different modes of operation, the reactor technology, the Synthesis and characteristics of the catalysts, and the mechanism of the reactions.
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Cobalt Fischer-Tropsch Synthesis: Deactivation by oxidation?
Catalysis Today, 2007Co-Authors: J. Van De Loosdrecht, A.m. Saib, J.w. Niemantsverdriet, P. J. Van Berge, B. Balzhinimaev, J. A. Dalmon, S. V. Tsybulya, J. L. VisagieAbstract:Cobalt catalysts as used in the Fischer-Tropsch Synthesis (FTS) are relatively expensive (as compared to iron) and need to have a high metal dispersion and long life to be able to offer a good balance between cost and performance. The oxidation of nano-sized metallic cobalt to cobalt oxide during Fischer-Tropsch Synthesis has long been postulated as a major deactivation mechanism. However, to date there is no consistent picture. This paper presents an extensive overview of the literature on this topic of deactivation by means of oxidation for unsupported as well as silica-, alumina- and titania-supported cobalt catalysts. Furthermore, it presents results on the deactivation of an industrial Co/Al2O3 catalyst as obtained by pseudo in situ X-ray diffraction, magnetic measurements and X-ray absorption near-edge spectroscopy. These analyses were performed to study the oxidation state of spent industrial Co/Al2O3 catalyst samples withdrawn from a slurry reactor operating under realistic FTS conditions, and it was concluded that oxidation can be ruled out as a major deactivation mechanism. Finally, these data together with all relevant literature were used to create a common view on the oxidation behaviour of metallic cobalt during FTS. The apparent discrepancies in literature on the oxidation behaviour of cobalt are most likely due to the lack of direct characterisation of the cobalt oxidation state and due to the comparison of catalysts with varying cobalt crystallites sizes, compared at different reactor partial pressures of hydrogen and water (PH2O/PH2). It was shown that the oxidation of cobalt can be prevented by selecting the correct combination of the reactor partial pressures of hydrogen and water (PH2O/PH2) and the cobalt crystallite size.
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Calcination of Co-Based Fischer–Tropsch Synthesis Catalysts
Topics in Catalysis, 2003Co-Authors: J. Van De Loosdrecht, P. J. Van Berge, Sean Barradas, Elsie Adriana Caricato, N.g. Ngwenya, P.s. Nkwanyana, M.a.s. Rawat, B.h. Sigwebela, Visagie Jacobus LucasAbstract:The calcination of Co-based slurry-phase Fischer–Tropsch Synthesis catalysts was investigated. Fischer–Tropsch Synthesis is part of the gas-to-liquids (GTL) process that produces gas oil and naphtha from natural gas. For the GTL process, the preparation of highly active Co-based catalysts is of utmost importance. This paper shows that the conditions during the calcination of impregnated cobalt precursors have a significant influence on the performance of the final catalyst. The options of calcination in rotary kilns, furnaces and fluidized-bed reactors were considered. It was found that the catalyst performance is strongly dependent on the heating rate and the air-space velocity during the preferred option of fluidized bed calcination. The postulation that Co3O4 is not the preferred oxide phase of the calcined intermediate catalyst is supported by a temperature-programmed reduction (TPR) study.