Hydroisomerization of C6–C8 n-alkanes, cyclohexane and benzene over palladium and platinum beta catalysts agglomerated with bentonite Original Research Article

Hydroisomerization of three linear alkanes (n-hexane, n-heptane and n-octane), cyclohexane and benzene was studied over two bifunctional catalysts based on beta zeolite agglomerated with bentonite, and as the metallic functions, palladium and platinum. In both catalysts, the reactivity of n-alkanes increased with the chain length due to enhanced adsorption properties. n-Octane was converted in a major extent than both n-heptane and n-hexane. However, the presence of cracking processes was more evident when the former was fed to the reactor. The conversion of cyclohexane (cC6) was clearly temperature dependent. In fact, the selectivity towards the dehydrogenation to benzene increased with increasing reaction temperatures. The conversion of benzene dropped as the temperature was increased. The higher hydrogenating capacity of platinum was the responsible of the higher benzene conversion values obtained with the platinum catalyst.The influence of each individual alkane on the catalytic activity of the others was studied by examining the reactivity of binary and ternary mixtures of alkanes in the hydroisomerization reaction. The inhibition by cyclohexane was higher due to its well known preferential adsorption over the zeolite. The simultaneous hydroisomerization of benzene and two linear alkanes favoured the partial conversion of the latter, but not the selectivity towards alkane isomers.