碱处理调变ZSM-5孔结构及甲苯甲醇烷基化制对二甲苯性能研究

Large grain ZSM-5 zeolite is prepared via hydrothermal method. A series of hierarchical porous ZSM-5 catalysts with large grains are obtained by adjusting alkali species and treatment time during alkali treatment. The catalysts are characterized by XRD, SEM, Ar-adsorption and thermogravimetry. Their catalytic performances are evaluated in the selective alkylation of toluene with methanol, and the effects of porous diameter of the catalysts on the conversion rate of toluene and the selectivity of p-xylene are studied. It is found the catalyst that has been treated by 0.2 mol•L^-1 of TPAOH solution with a liquid-solid ratio of 30 mL•g^-1 at 65℃ for 30 minutes performs the best performance. The average selectivity of p-xylene and the conversion rate of toluene can reach 68.36% and 11.24%, respectively over the optimal catalyst without modification in 30 h, while the carbon deposition rate is only 53% of the parent.