Cumene disproportionation over micro/mesoporous catalysts obtained by recrystallization of mordenite

Micro/mesoporous materials with different contribution of micro/mesoporosity have been studied in cumene disproportionation. The materials were prepared by recrystallization of mordenite and characterized by X-ray diffraction, nitrogen adsorption–desorption, transmission electron microscopy, infrared spectroscopy, and temperature-programmed desorption of ammonia. Micro/mesoporous materials with a low degree of recrystallization showed remarkably high activity and stability with respect to the parent and desilicated mordenites. The enhanced catalytic activity is due to a high zeolitic acidity combined with improved accessibility of active sites and transport of bulky molecules provided by uniform and homogeneously distributed intracrystalline mesopores. The high catalyst resistance to deactivation is due to two reasons: i) the improved transport of bulky products, which prevents the catalyst from the formation of “soft” coke inside the zeolite pores; ii) the coating of the zeolite with a mesoporous layer, which prevents the formation of “hard” coke on the external surface of the crystal.