Effects of Synthesis Method on the Localization of Aluminum Atoms and on Catalytic Performance of BEA Zeolite in Toluene Disproportionation

The physicochemical properties of BEA zeolites with SiO₂/Al₂O₃ ratios of about 40–50 and 200–250 synthesized in fluoride and alkaline media have been characterized, and their catalytic activity have been tested in liquid-phase disproportionation of toluene. It has been found that samples with a close SiO₂/Al₂O₃ ratio obtained by fluoride synthesis have a smaller number of acid sites. The samples with lower SiO₂/Al₂O₃ ratios exhibite a higher activity in toluene disproportionation than the samples with lower Al content, regardless of the synthesis method. The BEA zeolites that have Al atoms in the T6 positions of the framework which are more active. Synthesis in an alkaline medium promotes the localization of aluminum at the T6 position.