Studies on Alkylation of Toluene with Tert-butyl Alcohol over USY Zeolite

Catalytic performances of zeolite molecular sieves ( HM, USY, Hβ and HZSM-5) were investigated for the alkylation of toluene with tert-butyl alcohol in a 100 mL stainless steel batch reactor equipped with a stirrer, and the physical chemical properties of the above catalytic zeolites were characterized by ammonia program temperature desorption (NH3-TPD) and pyridine infrared spectroscopy (Py-IR) techniques. The results show that, besides the acid amount of catalyst, both the acid type and pore structure of the zeolites are the key factors influencing the catalytic behavior. The Lewis acid sites in catalyst mainly act as the active centers for the tert-butylation of toluene, and the strong acid sites do not favor the selectivity of target product. For the USY zeolite catalyst, which shows high catalytic conversion and selectivity, the influence of reaction conditions on tert-butylation of toluene were evaluated. The results show that the toluene conversion of 46.4%, the tert-butyltoluene (TBT) selectivity of 97.0% and the para-tert-butyltoluene (p-TBT) selectivity of 65.9% can be obtained by using the USY zeolite with calcination temperature 623 K as catalyst and under the suitable conditions as fallows: The reaction temperature and reaction time are 180℃ and 4 h, respectively, the initial pressure is 0.6 MPa, the molar ratio of tert-butyl alcohol to toluene is 2 and the cyclohexane is used as solvent.