Hydrodecyclization of Methylcyclopentane and Benzene in the Presence of a Reforming Catalyst

Hydrodecyclization reaction of methylcyclopentane (MCP) and benzene was studied under the conditions close to commercial reforming processes, and in the presence of a platinum-alumina reforming catalyst poisoned by coke and/or thiophene or activated by chloride.Decyclization reaction of MCP takes place competitively on two different kinds of active site. One of them is highly active, but is easily poisoned by small amount of thiophene added to the feed or moderate amount of coke deposited on the catalyst, while the other one is relatively less active, but is little affected by those poisons. The former would be on the surface of platinum, and the latter is perhaps acid sites of the alumina carrier.The rate of hydrodecyclization of MCP-including small amount of hydrocracking-, which was catalyzed by each site mentioned above was nearly of first order with respect to the partial pressure of MCP. And the rate of isomerization of MCP to six-membered ring compounds was also observed to be of first order with respect to the partial pressure of MCP.From the experiment of chloride activation, it seems that decyclization reaction of MCP can take place on relatively weak acid sites, while isomerization to six-membered ring takes place only on relatively strong acid sites.According to the kinetic discussion on hydrodecyclization of MCP and benzene, it is concluded that the rate constant of cyclization of n-hexane to MCP is higher than that of n-hexane to six-membered ring, and the rate constant of MCP to six-membered ring is much higher than that of n-hexane to MCP, under the conditions close to commercial reforming processes, using the catalyst moderately poisoned by coke and sulfur compounds.