A kinetic study of benzene alkylation with ethane into ethylbenzene over bifunctional PtH-MFI catalyst

Benzene alkylation with ethane into ethylbenzene (EB) was studied at 370 °C over a PtH-MFI bifunctional catalyst of high acidity (Si/Al = 15). Highly selective and stable catalyst operation was observed at benzene conversions up to 10–12%, which are close to the thermodynamic equilibrium conversion value of 13.5%. Kinetic analysis of the experimental data reveals that EB is formed via two consecutive reaction steps: (i) ethane dehydrogenation into ethene over Pt sites and (ii) benzene alkylation with ethene over acid sites. These reactions dominate at low contact times and benzene conversions up to 10-12%. At higher conversions (i.e. higher contact times) other reactions start to compete with the EB formation steps leading to a steep drop in the EB selectivity and to a decrease in the catalyst stability. The analysis of these side reactions results in a better understanding of the requirements for the selective and stable benzene alkylation with ethane into EB over bifunctional zeolite catalysts.