纳米晶堆积多级结构ZSM-5分子筛的设计合成及其催化甲醇制丙烯反应性能

采用硅凝胶原位转化自组装的方法,并且没有使用第二模板剂或有机添加剂情况下,成功地水热合成了纳米晶堆积多级结构ZSM-5分子筛。对合成样品进行了N2吸附-脱附、SEM、TEM和XRD表征,并考察其催化甲醇转化制丙烯(MTP)反应性能。结果表明,多级结构ZSM-5分子筛由50~90nm的ZSM-5晶体堆积而成,具有丰富的介孔结构;其介孔孔容和外比表面积相对常规ZSM-5分子筛和纳米晶ZSM-5分子筛都有较大的提高,并且结晶度良好。相对于纳米晶ZSM-5分子筛,纳米晶堆积多级结构ZSM-5分子筛由于其结构上的优势,具有更好的扩散性能,能够有效地提高催化寿命及丙烯选择性,在产品分离上也具有极大的优势。

Design and Synthesis of Hierarchical ZSM-5 Zeolite and its Catalytic Performance of MTP Reaction

 Nanocrystal aggregates hierarchical ZSM-5 zeolite was synthesized without other organic additives and secondary template than TPAOH template, and characterized by N₂ adsorption-desorption, SEM, TEM and XRD methods. Its catalytic performance in MTP reaction was investigated. The results showed that hierarchical ZSM-5 zeolite with a particle size of 50-90 nm was formed by the aggregation of lots of nanocrystals, possessing rich mesopores with remarkably larger external surface area and mesopore volume, and exhibited the excellent catalytic performance in MTP reaction with higher propylene selectivity and longer catalytic lifetime, compared with conventional ZSM-5 zeolite and nanocrystal ZSM-5 zeolite. Furthermore, the hierarchical ZSM-5 zeolite could be easily separated from the reaction products via filtration..