两步晶化法合成纳米SAPO-34分子筛及其催化性能

分别以拟薄水铝石、硅溶胶和磷酸为铝源、硅源和磷源,四乙基氢氧化铵为模板剂,采用两步水热晶化法合成出粒径为200～300 nm的纳米级SAPO-34分子筛.采用X射线衍射(XRD)、X射线荧光光谱(XRF)、29Si 、27Al、31P MAS NMR、SEM、BET和NH3-TPD等手段对合成的SAPO-34分子筛进行...

Two-step Crystallization Synthesis and Catalytic Performance of Nano-scaled SAPO-34 Molecular Sieve

In this study, nano-scaled SAPO-34 molecualr sieves with size in the range of 200~300 nm were synthesized by the two-step crystallization and H2O2 oxidation process, with pseudoboehmite, colloidal silica and H3PO4 as sources of aluminum, silicon and phosphorous and TEAOH as templates. The prepared SAPO-34 was characterized by XRD, SEM, NH3-TPD, BET and so on. The catalytic performance of the SAPO-34 on the methanol-to-olefins reactions (MTO) was carried out on a fixed bed. The results showed that the particle size of the SAPO-34 could be effectively modulated by the crystallization temperature of the two-step crystallization process. In particular, when the first and second crystallization were conducted at 130℃ and 180℃, cubic SAPO-34 with 200~300 nm size could be successfully synthesized. Compared with the micro-scaled SAPO-34 prepared by the traditional hydrothermal process, the nano-scaled SAPO-34 crystals synthesized here showed better performance in the MTO reaction and the selectivity of C2~C4 and the lifetime for one-turn could attained about 92% and 10 hours, respectively.