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

Abstract

Summary: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.

Hydrocracking of n-Hexane and Cyclohexane over Zeolites

“…per gram mole for hydrocracking cyclohexane. These apparent activation energies compared well to literature data handled in the same manner (Hartwig, 1964;Iijima et al, 1963).…”

Platinum/Alumina Catalysts in Reforming Methylcyclopentane

“…Selectivity has been investigated much more thoroughly, and several different ratios between the products have been reported. Of greatest interest for the present study is the work by Iijima et al (1963), who observed that the ring opening products are formed in the ratios 2MP:3MP:nHx = 2:1:2 on a fresh catalyst, while an aged (coked) catalyst and a sulfur poisoned catalyst gave higher percentages of nHx in the products. These observations are nearly identical with those obtained in the present study.…”

“…and Rohrer (1961) found with pn2 > 6 atm that a as well as ß is negative. Iijima et al (1963) found £()bs = 30-35 kcal/mol and Granhi/j (1972) found £"bs = 52.4 ± 13.7 kcal/mol and ß < 0 for high p h2.…”

“…Little information on the kinetics of the ring opening reactions is found in the literature. Iijima et al (1963) found £()bs to be ~30-35 kcal/mol, Smith et al (1971) found that nHx is the major ring opening product over a sulfur poisoned catalyst, and suggest that it is formed from MCP and MCP= in equilibrium by first-order reactions. Granh^j (1972) a catalyst, where nHx is the major ring opening product.…”