不同空间群SAPO-11分子筛对正辛烷异构化反应的催化性能  

Catalytic Performance of SAPO-11 Zeolite with Different Spacers for Isomerization of Octane

作　　者：刘月明[1] 张凤美[2] 舒兴田[2] 何鸣元[1] 

机构地区：[1]华东师范大学离子液体化学研究中心,上海200062 [2]中国石油化工股份有限公司石油化工科学研究院,北京100083

出　　处：《催化学报》2003年第10期779-782,共4页

摘　　要：不同条件下合成的SAPO 11分子筛 ,经焙烧后其XRD谱发生不同的变化 .分析表明 ,SAPO 11分子筛晶胞的对称性发生不同的变化 :有保持Icm2空间群的 ,有从Icm2空间群转变为Pna2 1空间群的 .空间群发生变化的分子筛其晶胞收缩可达7 0 % .考察了不同空间群SAPO 11分子筛对n C08异构化反应的催化性能 .结果表明 ,具有Icm2空间群的SAPO 11分子筛的催化性能好 ,具有Pna2 1空间群的SAPO 11分子筛的催化性能差 .这是由于分子筛晶胞收缩 ,引起孔道结构发生变化 ,从而影响了其择形选择性 .SAPO 11 zeolite with special pore structure and tunable acidity shows its potential application in hydrocarbon isomerization. The spacer changes of SAPO 11 zeolite samples prepared by different methods before and after calcination were investigated. The effects of the spacer changes on the catalytic performance of SAPO 11 zeolite in hydrocarbon isomerization were studied. The XRD results showed that the unit cell symmetry of SAPO 11 zeolite changed after calcination. Some samples retained the spacer Icm2, and some samples changed from Icm2 to Pna2 1, and some samples had the mixture of Icm2 and Pna2 1. The spacer change from Icm2 to Pna2 1 led to the unit cell shrinkage of 7 00%. The Pd/SAPO 11 with different spacers was evaluated by n octane isomerization. The results showed that the isomerization of n octane is better over Pd/SAPO 11 with Icm2 than over that with Pna2 1. The shrinkage of unit cell showed that the compression of the framework took place along the elliptical channel ( c axis) and short axis of elliptical channel ( a axis), while the expansion occurred along the long axis of elliptical channels ( b axis). The larger the unit cell shrank, the more elliptical the elliptical channels. As a result, it was inconvenient for the product diffusion in the more elliptical channel, leading the product to be cracked deeply, thus the isomer selectivity decreased. Therefore, the SAPO 11 retaining Icm2 spacer after calcination had better catalytic performacne for hydrocarbon isomerization.

关 键 词：钯 SAPO-11分子筛 晶胞结构 空间群 正辛烷 异构化 异辛烷 

分 类 号：O643.3[理学—物理化学]