NaAlO2改性ZSM-5分子筛的制备及其在甲醇芳构化中的应用

采用NaAlO2和HCl两步法对ZSM-5分子筛进行改性，运用XRD、SEM、NH3-TPD、N2吸附-脱附、ICP-OES、TG等方法对改性前后的分子筛进行表征。结果表明:经NaAlO2改性后的ZSM-5分子筛中引入了介孔，且分子筛的晶型、酸性、微孔体积等保持较好，并具有较高的固相收率；酸洗前通过中间焙烧有利于消除孔道覆盖和恢复酸性。将改性后的分子筛应用于甲醇芳构化反应中，在温度400 ℃、压力0.15 MPa、质量空速1.9 h-1的反应条件下，经0.45 mol/L NaAlO2改性的分子筛反应效果最优，产物芳烃收率可达41.9%，BTX收率达32.7%；与原粉分子筛相比，产物芳烃收率提高了3.8百分点，BTX收率提高了4.4百分点；同时，其反应稳定性可达30 h，较原粉延长了1倍多。

METHANOL AROMATIZATION PERFORMANCE OF ZSM-5 MODIFIED BY NaAlO2

ZSM-5 zeolite was modified successively by sodium aluminate and HCl washing with a calcination between the two steps. The samples were characterized by XRD, SEM, NH3-TPD, N2 adsorption, ICP-OES, and TG techniques. The results show that mesopores were created, and a higher solid yield was obtained with the crystallinity, acidity and micropore volume largely preserved. Besides, the calcination before acid washing is in favor of eliminating the pore blocking and recovering the acidity. The methanol aromatization performance over the modified catalysts was investigated at the conditions of 400 ℃, 0.15 MPa and the weight hourly space velocity of 1.9 h-1. The ZSM-5 zeolite modified with 0.45 mol/L NaAlO2 presents the optimal performance. The aromatics yield reaches 41.9% and BTX yield is 32.7%, increased by 3.8 and 4.4 percentage points compared with catalytic activity of parent ZSM-5, respectively. Meanwhile, the modified catalyst’s lifetime is 30h, one more times than the parent zeolite.