ZSM-5凝胶体系硅铝比对SAPO-34/ZSM-5复合分子筛结构性质的影响

摘要

The SAPO-34/ZSM-5 composite zeolite has been synthesized via microwave hydrothermal coating method,and the effect of silicon to aluminum ratio(molar ratio) of parent ZSM-5 gel on microstructure and physicochemistry characteristics of SAPO-34/ZSM-5 composite zeolite was investigated.The microstructure,morphology,pore structure and the surface acid nature of the composite zeolite were characterized by using XRD,SEM,BET and NH3-TPD techniques.The results indicated that the silicon to aluminum ratio of parent ZSM-5 gel posed little impact on crystalline phase composition,but had a significant influence on the specific surface area,pore structure parameters and surface acidity of the synthesized composite products.When silicon to aluminum ratio was 150,the SAPO-34/ZSM-5 composite zeolite exhibits a distinct morphology of cladding crystal and novel physicochemistry characteristics of hierarchical pore(microporous volume 0.21 cm3/g and mesoporous volume 0.09 cm3/g) and a large amount of weak acid sites(0.209 mmol/g).%采用微波水热包覆法制备SAPO-34/ZSM-5复合分子筛.考察了ZSM-5凝胶体系硅铝摩尔比对复合分子筛微观结构和物化性质的影响,采用XRD、SEM、BET、NH3-TPD等手段对合成的复合分子筛微观结构、形貌、孔结构及表面酸性质等进行分析表征.结果表明,ZSM-5凝胶体系硅铝比对复合分子筛样品晶相组成影响较小,但对样品比表面积、孔结构参数及表面酸性质影响较大.硅铝比为150时,SAPO-34/ZSM-5复合分子筛具有包裹状特殊晶体结构及多级孔(微孔孔容0.21 cm3/g、介孔孔容0.09 cm3/g)和弱酸中心(0.209 mmol/g)独特物化性质.