Characterization and catalytic activity of CoMoHDS catalysts supported on alumina-MCM-41

A series of CoMo HDS catalysts supported on alumina with different amounts of aluminum-modified MCM-41 was prepared, characterized by different techni ques (S-BET, NH3-TPD, TPR, UV-VIS-DRS, HREM and NO adsorption analyzed by F TIR) and tested in the dibenzothiophene hydrodesulfurization reaction. The results show that the incorporation of MCM-41 to the catalyst formulation l eads to higher catalytic activity. The TPR results indicate a diminished in teraction of the Co and Mo phases with the support, compared to those exist ing in the alumina-supported catalyst. This decrease in the interaction cau ses the formation of greater amounts of polymeric Mo species and a decrease in the population of tetrahedral Co as CoAl2O4, as evidenced by the DRS re sults. The changes in the intensity and position of the NO adsorption LR ba nds indicate that an interaction between Co and Mo exists and that not all the Co present in the catalysts is completely sulfided, and therefore, may not contribute to the formation of the catalytically active Co-Mo-S mixed p hase. (C) 2000 Elsevier Science B.V. All rights reserved.