Hydrodesulfurization of Dibenzothiophene Catalyzed by Supported Metal Carbonyls(Part 3). Effects of Supports on Catalysts Prepared from Supported Anionic Molybdenum Carbonyls.

Abstract

In hydrodesulfurization (HDS) of dibenzothiophene (DBT) catalyzed by a supported anionic molybdenum carbonyl, [NEt4][Mo(CO)5(CH3COO)]/support (Et=ethyl group), the effects of supports (SiO2-Al2O3, Al2O3, SiO2, TiO2, NaY zeolite, HY zeolite HZSM-5, and active carbon) on catalytic activity and product selectivity were investigated in a pressurized flow reactor. The yields of hydrodesulfurization products, biphenyl (BP), cyclohexylbenzene (CHB), and bicyclohexyl (BCH) decreased in the order, SiO2-Al2O3>Al2O3>TiO2=Active carbon>SiO2>NaY zeolite=HZSM-5>HY zeolite. The rates of HDS per amount of molybdenum loaded decreased in the order, SiO2-Al2O3>TiO2>NaY zeolite>Al2O3>SiO2. When HY zeolite was used, hydrocracking occurred significantly and BP, CHB, and BCH were not produced. When active carbon was used, a substantial amount of DBT was adsorbed on it, and the material balance could not be completely obtained. From NO chemisorption and XPS measurement of the catalysts derived from silica-alumina supported anionic molybdenum carbonyls, it was deduced that presulfidation of [NEt4][Mo(CO)5(CH3COO)]/SiO2-Al2O3 and Mo(CO)6-triethylamine(NEt3)-ethanethiol (EtSH)/SiO2-Al2O3 systems would give a silica-alumina supported MoS2-x species which was active in HDS of DBT.