Ring enlargement of methylcyclopentane over Pt/(HZSM-48+pseudoboehmite) catalysts

Platinum catalysts loaded on a hybrid support, composed of HZSM-48 and pseudoboehmite, were applied to the synthesis of benzene through methylcyclopentane (MCP) reforming in order to investigate the effect of the addition of pseudoboehmite to Pt/HZSM-48 for ring-enlargement reaction. A total of 0.5 wt% of platinum was impregnated on the hybrid support by using the incipient wetness method. Catalyst characterization was performed with nitrogen sorption, X-ray diffraction, temperature-programmed desorption of NH₃, and infrared spectroscopy of adsorbed pyridine. It was found that mesoporous structures were well-developed in Pt/(HZSM-48 + pseudoboehmite) catalyst as a result of the pseudoboehmite addition, of which the average pore size was in the range of 7–8 nm. The presence of pseudoboehmite in the catalyst increases the total amount of acid sites and weakens the acid strength, compared with those of the Pt/HZSM-48 catalyst. Lewis acid sites were more abundant than Brönsted acid sites over the Pt/(HZSM-48+pseudoboehmite) catalysts. It was found that selectivity to the ring-enlargement reaction is dominant over selectivity to the ring-opening reaction over the Pt/(HZSM-48 + pseudoboehmite) catalysts. The benzene yield over Pt/(HZSM-48 + pseudoboehmite, 1:1) catalyst reached 65.1% at 450 °C and 0.3 h⁻¹. As well as being influenced by the mesoporous structure, the higher activity and selectivity in MCP reforming was also determined by appropriate acidity of the Pt/(HZSM-48 + pseudoboehmite) catalysts.