Unified kinetics of n-heptane hydroisomerisation over various Pt/zeolite catalysts

Abstract

Hydroisomerisation of n-heptane has been carried out over six Pt-loaded zeolite-based catalysts. The activity and selectivity of each catalyst under various operating conditions of temperature, pressure and time were studied. Generally, a low pressure and high temperature favoured the overall n-heptane conversion while the selectivity towards isomers decreased at high temperature as the overall conversion increased to a high value. Based on the initial rates, kinetic modelling of the experimental data was carried out using power law kinetics and a simplified dual-site Langmuir–Hinshelwood–Hougen–Watson (LHHW) model. The LHHW approach was found more appropriate in representing the experimental data obtained over each catalyst and a kinetic model equation developed on the basis of surface reaction rate controlling best fitted to the experimental data. The activation energies were found to be in the range 94–143 kJ mol–1.