Synthesis of small-sized ZSM-11 zeolite and its performance in n-octane catalytic cracking
Small grained hierarchical pore ZSM-11 zeolites were synthesized by dynamic crystallization using conventional hydrothermal synthesis with polyacrylamide(PAM)as the mesoporous template agent.In order to reduce the amount of organic template agent and the synthesis cost,ZSM-11 zeolite was synthesized by a pre-crystallization liquid method.A variety of techniques including XRD,cryogenic N2 physisorption,SEM,and NH3-TPD were used to characterize the synthesized samples.The relation of PAM with zeolite particle size and catalytic cracking reaction performance was investigated.It was found that the addition of PMA to the synthesis gel did not change the topology of ZSM-11 zeolites but significantly affected the morphology,pore structure,and acidity of the zeolites.The particle size of ZSM-11 zeolites would be greatly reduced,with the formation of mesoporous structure,and the amount of acid and acid strength of the sample were increased.In the evaluation of n-octane catalytic cracking reaction,the small crystal sized ZSM-11 gave higher reactivity,less hydrogen transfer reaction,and higher yield of propene.
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