Effect of ZSM-5 Zeolite Morphology on Catalytic Performance of Benzene-ethanol Alkylation
In this paper,four kinds of nano-ZSM-5 zeolites with different morphologies and sizes,including cyclic,lamelliform,spheroidal aggregates,and small particles,were prepared by hydrothermal methods.The synthesized zeolites were characterized by X-ray diffraction(XRD),scanning electron microscope(SEM),Brauer-emmett-teller(BET),solid state nuclear magnetic resonance(MAS-NMR)and ammonia temperature programmed desorption(NH3-TPD),and the effects of the morphology on the alkylation properties of benzene and ethanol were investigated.The experimental results showed that zeolites with different morphologies had similar weak acid peak strengths at the similar Si/Al ratio.The presence of short B-axes and hollow structures reduces the strength of the strong acid peak in zeolite,which directly affects the alkylation performance.The catalytic alkylation performance of the four zeolite forms decreased in the order of lamellar ZSM-5,cyclic ZSM-5,spheroidal aggregates ZSM-5,and small particle ZSM-5.Under the conditions of lower acid strength,larger specific surface area and pore volume,and more straight pores,the best alkylation performance of zeolite and the greater selectivity of ethylbenzene were achieved.
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