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研究以浸渍法和同晶置换法引入Zn对纳米ZSM-5分子筛催化己烯-1芳构化反应性能的促进作用。采用无模板剂的晶种引导法合成具有纳米尺度的ZSM-5分子筛。分别以传统浸渍法和同晶置换法制备Zn改性的纳米ZSM-5分子筛催化剂x Zn/HNZ5和y Zn/Al-HNZ5。采用XRD、XRF、N2物理吸附、SEM、NH3-TPD和Py-IR等分析手段对所制备样品的结构、化学组成以及酸性进行表征,并在480°C和质量空速为2.0 h-1的条件下对其催化己烯-1芳构化性能进行考察。与x Zn/HNZ5相比,y Zn/Al-HNZ5表现出更小的粒径尺寸和更高的Zn物种分散度,使其具有更大的晶间介孔和更均匀的酸中心分布。催化性能评价结果表明,Zn同晶置换改性的纳米ZSM-5分子筛具有更好的Brnsted和Lewis酸中心协同作用,能够显著地提高纳米ZSM-5分子筛的催化己烯-1芳构化反应收率和稳定性。
The impregnation method and the isomorphous substitution method were introduced to promote the catalytic effect of Zn on the hexene-1 aromatization of nano-sized ZSM-5 zeolite. ZSM-5 zeolite with nanometer scale synthesis was synthesized by using seedless guidance. Zn-modified zeolite ZSM-5 zeolite catalysts Zn x HnZ5 and y Zn / Al-HNZ5 were prepared by conventional impregnation and isomorphous substitution respectively. The structure, chemical composition and acidity of the prepared samples were characterized by means of XRD, XRF, N2 adsorption, SEM, NH3-TPD and Py-IR analysis, and the results were analyzed at 480 ° C and 2.0 h-1 Under the conditions of its catalytic hexene-1 aromatization performance were investigated. Y Zn / Al-HNZ5 exhibits smaller particle size and higher Zn species dispersion than x Zn / HNZ5, resulting in larger intergranular mesopores and a more uniform acid site distribution. The results of the catalytic performance evaluation show that the Zn-isomorphous substitution modified nano-ZSM-5 zeolite has a better synergistic effect between Brnsted and Lewis acid centers, and can significantly improve the catalytic hexene-1 aromatization of the nano-ZSM-5 zeolite Reaction yield and stability.