Effects of pore diameter on particle size, phase, and turnover frequency in mesoporous silica supported cobalt Fischer–Tropsch catalysts

[Display omitted] ▶ Silicas with large pore diameters support higher TOFs. ▶ Small pore diameters yield larger mole fraction of CoO. ▶ XRD on post-reduction and post-FTS materials indicate significant changes in dispersivity after reduction. A series of mesoporous silica supported cobalt catalysts f...

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Bibliographic Details
Published in:	Applied catalysis. A, General Vol. 388; no. 1; pp. 57 - 67
Main Authors:	Ghampson, I.T., Newman, C., Kong, L., Pier, E., Hurley, K.D., Pollock, R.A., Walsh, B.R., Goundie, B., Wright, J., Wheeler, M.C., Meulenberg, R.W., DeSisto, W.J., Frederick, B.G., Austin, R.N.
Format:	Journal Article
Language:	English
Published:	Kidlington Elsevier B.V 20-11-2010 Elsevier
Subjects:	Catalysis Catalysts Chemistry Co heterogeneous catalyst Cobalt Colloidal state and disperse state Diffraction Exact sciences and technology Fischer–Tropsch synthesis General and physical chemistry HMS Hydrogen reduction MCM-41 MCM-48 Particle size Pore size Porosity Porous materials SBA15 Silicon dioxide Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry Turnover frequency X-ray diffraction Co heterogeneous catalyst Turnover frequency MCM-48 Pore size SBA15 X-ray diffraction MCM-41 Fischer–Tropsch synthesis HMS Binary compound Particle size Support Hydrogen Cobalt Porous material Precursor Silica Supported catalyst Characterization Particle Chemical reduction Chemical reactivity Diameter Composition Fischer Tropsch synthesis Transition metal Reaction rate X ray diffraction Mesoporosity Heterogeneous catalysis Fischer-Tropsch synthesis Distribution Fischer Tropsch catalyst Frequency Surface area
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Summary:	[Display omitted] ▶ Silicas with large pore diameters support higher TOFs. ▶ Small pore diameters yield larger mole fraction of CoO. ▶ XRD on post-reduction and post-FTS materials indicate significant changes in dispersivity after reduction. A series of mesoporous silica supported cobalt catalysts for the Fischer–Tropsch reaction with pore diameters from 3 to 22 nm was synthesized and characterized. Detailed X-ray diffraction measurements were used to determine the composition and particle diameters of the metal fraction, analyzed as a three-phase system containing Co fcc, Co hcp and CoO. Catalyst properties were determined at three stages of catalyst history: (1) after the initial calcination step to thermally decompose the catalyst precursor into Co 3O 4, (2) after the hydrogen reduction step to activate the catalyst to Co and (3) after the FT reaction. Small Co hcp particles were detected in all reduced catalysts contributing significantly to the Co surface area. The reaction rate increased with the pore diameter of the silica support. The results indicate the importance of careful catalyst characterization in determining the factors that contribute to reactivity. In addition, the identification of significant quantities of two cobalt metal phases suggests that further study of the intrinsic activity of each phase, as well as the structural features of the supports that determine the distribution of cobalt phases and particle sizes is warranted.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	0926-860X 1873-3875
DOI:	10.1016/j.apcata.2010.08.028