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

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.