Hydroconversion of cyclohexene using catalysts containing PtPd, Ir and Re supported on H-ZSM-5 zeolite

The hydroconversion of cyclohexene (CHE) using catalysts containing 0.35 wt.% of either Pt, Pd, Ir or Re on H-ZSM-5 support as well as the unloaded H-ZSM-5 zeolite was carried out using a flow-type fixed-bed reactor in a continuous flow of H-2 gas. The hydroconversion of CHE was found to include its hydrogenation to CHA, dehydrogenation to benzene through cyclohexadienes (CHDEs) as intermediates, its isomerisation to the C-5 ring containing cycloolefins (methylcyclopentenes, MCPEs) followed by their hydrogenation to methylcyclopentane (MCPA). Moreover, hydrocracking and alkylation products (toluene and xylenes) were found to form at higher temperatures. Hydrogenation and dehydrogenation reactions not only took place on the metal sites, but also on the unloaded zeolite at comparatively higher temperatures. The hydrogenation/dehydrogenation activities of the current metals were found to be in the order: Pd > Pt > Ir > Re. However, rheniurn was almost catalytically inactive on all hydroconversion steps. (c) 2005 Elsevier B.V. All rights reserved.