Ga/ZSM-5催化剂上乙醇芳构化研究

Study on Ethanol Aromatization Over Ga/ZSM-5 Catalyst

采用Na2CO3水溶液处理法制备了多级孔ZSM-5分子筛,采用BET、NH3-TPD、SEM、XRD等手段进行了表征,研究了碱处理前后ZSM-5分子筛孔结构、表面酸性、形貌和晶相的变化。采用浸渍法制备了碱处理ZSM-5分子筛负载金属镓的Ga/ZSM-5催化剂。结果表明,碱处理后ZSM-5分子筛形成了较多介孔,ZSM-5分子筛的比表面积、孔容和孔径均有增加。比表面积由338 m2/g增大到364 m2/g,平均孔径由处理前的1.92 nm增大到37.94 nm。碱处理后ZSM-5分子筛的形貌和晶相变化不大,酸强度与酸量有所下降。在固定床反应器中进行了乙醇芳构化性能评价。在400℃、0.5 MPa、1.0 h-1的条件下,乙醇转化率接近100%,芳烃收率达到74.25%。

The hierarchical ZSM-5 zeolites were prepared by Na2CO3 aqueous solution treatment and characterized by BET, NH3-TPD, SEM and XRD. Changes of pore structure, surface acidity, morphology and crystal phase of ZSM-5 zeolites before and after alkali treatment were investigated. Using ZSM-5 zeolites as support,Ga/ZSM-5 catalyst was prepared by impregnation using alkali treatment. The results show that, the mesoporous formed in ZSM-5 zeolite by alkali treatment, and the surface area, pore volume and pore size increased. The specific surface area increased from 338 m^2/g to 364 m^2/g, and average pore diameter increased from 1.92 nm to 37.94 nm. The morphologies and crystal phases of ZSM-5 zeolites did not changed after the alkali treatment, acid strength and acid amount declined. Ethanol aromatization was conducted in a fixed bed reactor. Under the condition of 400 ℃, 0.5 MPa and1.0 h-1, the ethanol conversion and aromatics yield reached to 100% and74.25% respectively.