含N微孔SAPO-34分子筛的制备、表征及催化性能

PREPARATION AND CATALYTIC ACTIVITY OF N-CONTIONTAINING MICROPOROUS SAPO-34 MOLECULAR SIEVES

采用高温下NH3氮化的方法制备了含N微孔SAPO-34分子筛,采用XRD、BET、NH3-TPD和CO2-TPD等手段对SAPO-34分子筛氮化后的结构和酸碱性进行了表征。结果表明,SAPO-34分子筛经高温氮化后,仍具有良好的结晶度、晶体结构和高比表面积,表面酸中心强度和数目都有所降低,并产生了新的碱性中心。首次将含N的SAPO-34分子筛用于甲醇制烯烃(MTO)反应,与未氮化的SAPO-34分子筛相比,低碳烯烃的选择性明显提高,乙烯选择性从11.6%提高到39.7%。

Nitrogen containing SAPO-34 microporus molecular sieves were prepared by a secondary technique with a starting material of SAPO-34 treatment at elevated temperature by NH3. Comparing with precursor, after post treated at high temperature the obtained samples still kept high crystallinity and high specific surface area, detected by XRD and BET measurements. The characterization of NH3-TPD and CO2-TPD indicated that the acidity and basicity of N containing SAPO-34 were different from that of SAPO-34, and new basic sites were produced on its surface. The catalytic performance of N containing SAPO-34 for the reaction to prepare olefin from methanol （MTO） was investigated. It was found that light olefins selectivity over N containing SAPO-34 was more than that over SAPO-34, in which ethylene selectivity increased from 11.6% to 39.7%.