模板剂对ZSM-5分子筛甲醛环化制三聚甲醛性能的影响

以四丙基氢氧化铵、四丙基溴化铵、正丁胺和季戊四醇为模板剂水热合成ZSM-5分子筛，采用XRF、XRD、SEM、NH₃-TPD、Py-FTIR和²⁷Al MAS NMR等进行了表征，研究了模板剂对ZSM-5分子筛性质及甲醛制三聚甲醛催化性能的影响。结果表明，通过改变模板剂可改变ZSM-5分子筛的酸中心分布、表面酸性质和粒径；较大空间的孔道交叉位置的酸性中心、小催化剂粒径和高表面B酸/L酸比值有利于提高三聚甲醛选择性。以四丙基氢氧化铵为模板剂合成的ZSM-5分子筛的颗粒尺寸为240nm×240nm×150nm，分布于直形孔道和S形孔道的孔道交叉处的Br?nsted酸中心较多，甲醛转化率和三聚甲醛的选择性分别为30.15%和88.35%。

Effect of templates in ZSM-5 zeolite on the reaction performance of formaldehyde cyclotrimerization to trioxane

ZSM-5 zeolites were synthesized with different templates by hydrothermal method and characterized by XRF, XRD, SEM, NH₃-TPD, Py-FTIR, and ²⁷Al MAS NMR. The effect of templates on the catalytic performance of ZSM-5 zeolites in the trioxane synthesis was investigated. The results indicated that types of templates affected the distribution of acidity, the surface acidity and the particle size of the catalyst of the ZSM-5 zeolites. Acid sites located on the intersection of straight channel and S-channel, small particle size and high surface B acid /L acid ratio were favorable to enhancement of trioxane selectivity. Synthesized with tetrapropylammonium hydroxide, the ZSM-5 zeolite, of which the average particle size was 240nm×240nm×150nm and high acid sites distributed in the intersection of straight channel and S-channel, exhibited the formaldehyde conversion of 30.15% and trioxane selectivity of 88.35%.