以乙二胺为模板剂合成Y/ZSM-5复合分子筛

以乙二胺为模板剂,采用两步晶化法,在先合成ZSM-5分子筛的基础上合成出具有双微孔结构的Y/ZSM-5复合分子筛,考察了原料配比和溶液pH对合成产物的影响;采用X射线衍射、N2吸附-脱附、傅里叶变换红外光谱、扫描电子显微镜和NH3程序升温脱附法对Y/ZSM-5复合分子筛进行了表征,并与Y型及ZSM-5分子筛的机械混合物进行了比较;研究了Y/ZSM-5复合分子筛对丁烷裂解和芳构化反应的催化性能。实验结果表明,当n(S iO2)∶n(A l2O3)=20~30,pH=12.0~12.5时,可合成出Y/ZSM-5复合分子筛;Y/ZSM-5复合分子筛的结构和性能明显不同于Y型及ZSM-5分子筛的机械混合物;在650℃时,Y/ZSM-5复合分子筛对丁烷裂解和芳构化反应的乙烯和丙烯选择性达40.72%,苯和甲苯选择性达27.46%。

Synthesis of Y/ZSM-5 Composite Molecular Sieve with Ethylenediamine as Template

Y/ZSM-5 composite molecular sieve was hydrothermally synthesized by two-step crystallization with ethylenediamine as template.Effects of n(SiO_2) ∶n(Al_2O_3)and pH,on synthesis were investigated.The synthesizing conditions can affect structure of product Y/ZSM-5 composite molecular sieve.The well-crystallized Y/ZSM-5 composite molecular sieve can be synthesized when(n(SiO_2)) ∶(n(Al_2O_3)) 20-30 and pH 12.0-12.5.Y/ZSM5 composite molecular sieve was characterized by means of XRD,N_2 adsorption-desorption,FTIR,SEM and NH_3-TPD.Y/ZSM-5 composite molecular sieve is different in structures and properties from mechanical mixture of NaY and ZSM-5 molecular sieves.When cracking and aromatization of n-butane/i-butane were carried out over Y/ZSM-5 composite molecular sieve at 650℃,selectivity to ethylene and propylene can reach 40.72% and selectivity to benzene and toluene can reach 27.46%.