查看更多>>摘要：The conversion of CO2 into specific aromatics by modulating the morphology of zeolites is a promising strategy.HZSM-5 zeolite with hollow tubular morphology is reported.The morphology of zeolite was precisely controlled,and the acid sites on its outer surface were passivated by steam-assisted crystalliza-tion method,so that the zeolite exhibits higher aromatic selectivity than sheet HZSM-5 zeolite and greater p-xylene selectivity than chain HZSM-5 zeolite.The tandem catalyst was formed by combining hollow tubular HZSM-5 zeolites with ZnZrOx metal oxides.The para-selectivity of p-xylene reached 76.2％at reaction temperature of 320 ℃,pressure of 3.0 MPa,and a flow rate of 2400 mL g-1 h-1 with an H2/CO2 molar ratio of 3/1.Further research indicates that the high selectivity of p-xylene is due to the pore structure of hollow tubular HZSM-5 zeolite,which is conducive to the formation of p-xylene.Moreover,the passivation of the acid site located on the outer surface of zeolite effectively prevents the isomerization of p-xylene.The reaction mechanism of CO2 hydrogenation over the tandem catalyst was investigated using in-situ diffuse reflectance Fourier transform infrared spectroscopy and density functional theory.The results showed that the CO2 to p-xylene followed a methanol-mediated route over ZnZrOx/hollow tubular HZSM-5 tandem catalysts.In addition,the catalyst showed no significant deacti-vation in the 100 h stability test.This present study provides an effective strategy for the design of cat-alysts aimed at selectively preparing aromatics through CO2 hydrogenation.
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