Catalysis Today, Vol.123, No.1-4, 198-207, 2007
Hydrodesulfurization of 4,6-dimethyldibenzothiophene over Pt, Pd, and Pt-Pd catalysts supported on amorphous silica-alumina
The activities and selectivities of Pt, Pd, and Pt-Pd supported on amorphous silica-alumina (ASA) in the hydrodesulfurization (HDS) of 4,6-dimethyldibenzothiophene (4,6-DM-DBT) were investigated. The ASA-supported catalysts had much higher activities than alumina-supported catalysts, due to the creation of electron-deficient metal particles. Pd had a high hydrogenation activity for 4,6-DM-DBT, but the removal of sulfur from 4,6-DM-DBT and its HDS intermediates occurred faster over Pt than over Pd. Comparison of two Pt/ASA catalysts with different Pt loadings showed that the metal dispersion strongly influenced the product selectivity. Larger metal particles led to relatively faster hydrogenation and slower C-S bond breaking. Bimetallic Pt-Pd catalysts were much more active than the monometallic constituents, indicating that the metal particles were alloyed. Acid-catalyzed cracking and isomerization occurred especially over Pt/ASA. (c) 2007 Elsevier B.V. All rights reserved.
Keywords:hydrodesulfurization;4,6-dimethyldibenzothiophene;dibenzothiophene;platinum;palladium;Pt-Pd catalysts;amorphous silica-alumina