KINETICS OF SIMULTANEOUS ISOMERIZATION AND CRACKING OF NORMAL-HEXANE OVER PT-AL2O3

Simultaneous isomerization and cracking of n-hexane has been studied over a commercial 0.35 wt% Pt Al2O3 catalyst at 420 to 450 °C, a total pressure of 10.5 bar and a hydrogen/hydrocarbon partial pressure ratio of 20 in a fixed-bed reactor. Under these reaction conditions the individual reactions were assumed to be pseudomonomolecular and the method of Wei and Prater was used to obtain isomerization and cracking rate constants. The proposed reaction scheme consisted of a reversible three-component system, namely isomerization of n-hexane to 2-methylpentane and 3-methylpentane, and three irreversible steps, namely CC bond rupture of n-hexane, 2- and 3-methylpentane yielding C1C5 alkanes, and isomerization to 2,2- and 2,3-dimethylbutane. From measurements of the equilibrium composition, an artificial straight line reaction path, and a curved reaction path, the pseudomonomolecular reaction rate constant matrix was obtained. © 1979.