Mixture effects in alkane/cycloalkane hydroconversion over Pt/HUSY: Carbon number impact

Abstract

Cycloalkanes are known to impact the metal–acid balance of the hydrocracking of n-alkanes with similar carbon number, however, how this impact varies with the carbon number of the components involved is still to be understood in more detail. For this purpose, the hydroconversion of n-octane and tert-butylcyclohexane, and n-decane and methylcyclohexane mixtures was investigated in this work over Pt/HUSY catalyst in both the ideal and the nonideal hydrocracking regime. Irrespective of the hydrocracking regime for pure n-octane, its conversion and isomer yields were significantly lowered upon admixture of tert-butylcyclohexane. On the other hand, n-octane admixture did not impact the tert-butylcyclohexane conversion nor its cyclic isomer yields. Upon methylcyclohexane admixture with n-decane, no impact was observed over the catalyst ensuring ideal hydrocracking of pure n-decane. Over the catalyst with significantly lower Pt loading, which does not ensure ideal hydrocracking of n-decane, methylcyclohexane lowered the n-decane conversion. A slightly negative impact of n-decane admixture on methylcyclohexane conversion was also observed. The observed effects are mainly attributed to the differences in adsorption strengths within the zeolite pores on top of differences in alkane and cycloalkane adsorption on the metal sites.