Characterization and hydrodesulfurization activity of CoMo catalysts supported on sol-gel prepared Al2O3

A series of CoMo/Al2O3 catalysts was prepared by impregnation on a series of alumina powders synthesized by the sol-gel method with different hydrolysis ratios R (defined as [H2O]/[aluminum-tri-sec-butoxide (ASB)]; R=3,4,...,12,13). The oxide precursors were characterized and subsequently tested in...

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Published in:Applied catalysis. A, General General, 2005-06, Vol.287 (1), p.135-145
Main Authors: DUMEIGNIL, Franck, SATO, Koichi, IMAMURA, Motoyasu, MATSUBAYASHI, Nobuyuki, PAYEN, Edmond, SHIMAD, Hiromichi
Format: Article
Language:English
Subjects:
Catalysis
Chemical Sciences
Chemistry
Colloidal gels. Colloidal sols
Colloidal state and disperse state
Exact sciences and technology
General and physical chemistry
Porous materials
Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry
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Summary:A series of CoMo/Al2O3 catalysts was prepared by impregnation on a series of alumina powders synthesized by the sol-gel method with different hydrolysis ratios R (defined as [H2O]/[aluminum-tri-sec-butoxide (ASB)]; R=3,4,...,12,13). The oxide precursors were characterized and subsequently tested in the hydrodesulfurization (HDS) of thiophene, dibenzothiophene (DBT), and 4,6-dimethyldibenzothiophene (4,6-DMDBT). Mainly due to their large pore diameters of ca. 6nm, the catalysts prepared from the alumina with hydrolysis ratio R=7-10 showed higher HDS activity compared with the activities of the other prepared catalysts. The effect of the pore diffusional limitation was more significant than expected, due to the ink-bottle shape of the pores of the prepared catalysts with hydrolysis ratio R < 8 and R > 10. Due to highly dispersed CoMo active phase, the HDS activity of the prepared catalysts with hydrolysis ratio R=8 and 9 for thiophene was similar to that of a reference industrial catalyst that was designed and manufactured for deep HDS of diesel fuel fractions. Furthermore, the HDS activity of the prepared catalysts with hydrolysis ratio R > 5 for DBT was higher than that of the reference industrial catalyst. For 4,6-DMDBT, however, the reference industrial catalyst showed higher HDS activity compared with the activities of the prepared catalysts. Relatively high HDS activity was observed for the prepared catalysts with R=9 and 10 with cylindrical pore shape and with a high proportion of strong acid sites. The strong acidity supposedly enhanced the hydrogenation activity of the catalysts that was essential for the HDS of 4,6-DMDBT.
ISSN:0926-860X
1873-3875
DOI:10.1016/j.apcata.2005.03.034