硅磷酸铝分子筛SAPO-34稳定性的研究

Investigation on the Stability of Silicoaluminophosphate Molecular Sieve SAPO-34

利用差热分析（ＤＴＡ）、原位ＸＲＤ技术研究了ＳＡＰＯ－３４分子筛原粉样品的晶体结构在模板剂烧除过程以及环境气氛中的变化情况。采用１０７３Ｋ下的高温焙烧和水蒸汽处理以及甲醇转化试验跟踪考察了该分子筛在结构和催化性能上的稳定性。

The stability of silicoaluminophosphate molecular sieve SAPO-34 has been investigated with DTA,XRD and severe treatment at high temperature.DTA tests of as-synthesized and calcined samples revealed that the framework destruction temperature of SAPO-34 is over 1300K.According to in situ XRD studies,no framework collapse happens during the organic template removing process at the temperature of ～973K and the following cooling period.The crystallinity of SAPO-34 sample remains over 80% and its catalytic performances in methanol conversion change little after 300h continuous calcination in air at 1073K.The successive steaming treatment over 45h at 1073K only destroyed the sample′s crystallinity of less than 20% and damaged a little of its catalytic property,showing the high hydrothermal stability of SAPO-34.The surface composition analysis results discloses that calcination,especially steaming at 1073K gives rise to the deprivation of aluminum and phosphorus from SAPO-34 framework.