Synthesis Of CHA/AEI Intergrown Framework Structure SAPO Molecular Sieve And Study Of Catalytic Performance In 1-butene Cracking

Zeolite is natural or chemical substances with synthetic mesh structure,according to a large aperture small can be divided into three categories:Zeolites,mesoporous and macroporous molecular sieve.Composite Zeolite appears to make up for the shortcomings of a single pore zeolite,and can play to their strengths,which greatly expanded the scope of application of molecular sieve.In this paper,by hydrothermal synthesis method,tetraethyl ammonium hydroxide（TEAOH）as the template,successful synthesized of SAPO-18/SAPO-34 intergrown molecular sieve（SAPO-18 with AEI framework-structure,SAPO-34 with CHA framework structure）,and their characterizations of XRD,SEM,BET and NH₃-TPD were characterized.At the same time,we successfully synthesized the intergrown molecular sieves by synthesis method of changing the template.The synthesized CHA/AEI intergrown molecular sieve was applied in 1-butene cracking,studying the effects of reaction conditions（reaction temperature,and 1-butenen WHSV）and catalytic properties comparison of CHA/AEI intergrown molecular sieve,SAPO-18,SAPO-34,and simple mechanical mixing in 1-butene cracking catalytic reactions.In this study,CHA/AEI intergrown molecular sieve was successful prepared under the hydrothermal synthesis conditions,the molar ratio of raw material was:0.1SiO₂/TEAOH/H₃PO₄/Al₂O₃/xH₂O（TEAOH as template,x=25 or 35）.In the synthesis process,it was very critical to add raw materials with order,and the crystallization speed should be heated as a certain temperature rise crystallization temperature by stirring.CHA/AEI intergrown molecular sieve was crystal aggregates,low acidity,and low specific surface area.CHA/AEI intergrown molecular sieve was successfully synthesized by mixed template,and achieved the expected effect.The synthesis of CHA/AEI intergrown molecular sieve was applied in butene cracking,studied the influence of the reaction temperature and WHSV on the CHA/AEI intergrown molecular sieve in 1-butene cracking,investigated and compared the catalytic performance of SAPO-18,SAPO-34 and mechanical mixing in 1-butene catalytic cracking reaction,and the CHA/AEI intergrown molecular sieve.The results showed that reaction conditions were:temperature T=550℃,WHSV=3.5h^-1,TOS=1min,catalytic performance of CHA/AEI intergrown molecular sieve was optimal in 1-butene cracking,the propene yield was 45.11%,selectivity was 61.09%,the ethene yield of 21.55%,the selectivity was 29.19%;at the same time,higher yield of propene and selectivities of ethene and propene on CHA/AEI intergrown molecular sieve than that on SAPO-18,SAPO-34 and a simple mechanical mixing in 1-butene catalytic cracking reactions under the optimized reaction conditions.