气相晶化法合成SAPO-34分子筛

分别以磷酸、拟薄水铝石和硅溶胶为磷源、铝源和硅源,吗啉和三乙胺为模板剂,采用气相晶化法在不同条件下合成了SAPO-34分子筛。研究了各种因素对气相晶化法合成SAPO-34分子筛的影响,确定了制备SAPO-34分子筛的最佳合成条件。干胶配比、干胶中的硅铝比和晶化温度对气相晶化法合成SAPO-34分子筛有重要影响,最佳干胶配比为n(SiO2)∶n(Al2O3)∶n(P2O5)∶n(H2O)=1.0∶1∶2∶30,最佳晶化温度为180℃,但在160,140℃时也能合成出纯SAPO-34分子筛。模板剂不同,合成的分子筛不同,搅拌有利于气相晶化。以制备的SAPO-34分子筛为催化剂催化甲醇制低碳烯烃反应结果表明,甲醇转化率达98%以上,乙烯和丙烯的总选择性达80%以上。

Synthesis of SAPO-34 Molecular Sieves by Gas Phase Crystallization

SAPO-34 molecular sieve was synthesized from phosphoric acid,AlO(OH)·3H2O and silica sol with triethylamine or morpholine as templates by gas-phase crystallization.The effects of various factors on synthesis of SAPO-34 molecular sieve were studied.Material composition,n(SiO2) ∶n(Al2O3) in dry gel and crystallization temperature show important influences on synthesis of SAPO-34 molecular sieve.Optimal conditions are n(SiO2) ∶n(Al2O3) ∶n(P2O5) ∶n(H2O) 1.0 ∶1 ∶2 ∶30 and crystallization temperature 180 ℃.SAPO-34 molecular sieve can also be prepared at 160 ℃ and 140 ℃.By using different templates,different molecular sieves can be obtained.Stirring is advantageous to the gas-phase crystallization.Conversion of methanol and the selectivity to both ethylene and propylene reach more than 98% and more than 80% respectively in methanol-to-olefin process on SAPO-34 molecular sieve catalyst.