Toluene Disproportionation Reaction over Modified HY and LaHY Catalysts

• Published in: Applied catalysis 1990, Vol.63 (1), p.91-106
• Main Authors: Leu, Li-Jen, Kang, Ben-Chang, Wu, Shwu-Tzy, Wu, Jung-Chung
• Format: Article
• Language: English
• Subjects: acid sites; benzene; catalyst preparation (ion exchange; Chemistry; dealumination; Exact sciences and technology; FT-IR; General and physical chemistry; Keywords: toluene disproportionation; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; XRD; xylene; zeolites
• ISSN: 0166-9834
• DOI: 10.1016/S0166-9834(00)81708-X

A series of catalysts were prepared by the modification of NH4NaY zeolite. Effects of pretreatment such as calcination, steaming, NH+4 ion-exchange, and La3+ ion-exchange of zeolite Y on the reaction of toluene disproportionation and its transient period were studied. It was found that the acid strength of zeolite increased with pretreatment by La3+ ion-exchange. The hydrothermal treatment caused more significant dealumination of zeolite than it did calcination, and the presence of La3+ ion in the zeolite could inhibit the dealumination process. It also indicated that the higher the acid strength, the higher the initial conversion, and the shorter the transient period; however, the catalysts calcined at 773 K gave the maximum average conversion. It was concluded that the best way to prepare Y zeolite catalysts for the toluene disproportionation reaction was NH+4 ion-exchange followed by La3+ ion-exchange, and then calcination at 773 K followed by another NH+4 ion-exchange. The appropriate amount of La3+ in LaHY zeolite was found to be 3.07-4.80 wt.-% for the reaction of toluene disproportionation.