2D HZSM-5 nano-sheet with different b-axis thickness and Si/Al atom ratios were synthesized by seed-induced method under the hydrothermal conditions, using tetrapropylammonium bromide as the template, ethylamine as the mineralizer, silica sol as the silicon source, aluminium chloride as the aluminium source and the 60 nm silicate-1 as the crystal seed, respectively. And the 2D hierarchical HZSM-5 nano-sheet were obtained by alkaline treatment with different sources, including NaOH treatment, tetrapropylammonium hydroxide(TPAOH) treatment, and NaOH with TPAOH co-alkaline treatment. The structure and acidity of the samples were characterized by means of X-ray diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM), Ar adsorption-desorption, ammonia temperature-programmed desorption(NH3-TPD), X-ray fluorescence(XRF) and X-ray photoelectron spectroscopy(XPS). The effects of Si/Al atom ratio and the thickness of b-axis on the alkylation of benzene with dilute ethylene were investigated. The research results show that, under the reaction conditions of 360 ℃, 1.4 MPa, the molar ratio of benzene/ethylene is 6, and the concentration and weight hourly space velocity(WHSV) of ethylene were 15% and 1.5 h-1, the conversion of benzene decreased slightly with the increasing of Si/Al atom ratio, the ethyl selectivity maintained above 99.2%, while the selectivity of toluene and xylene decreased from 0.11% and 0.09% to 0.05%, respectively. The HZSM-5 catalysts with different b-axis thickness were evaluated under the condition of benzene/ethylene is 1, the microscale HZSM-5 with the high silica content deactivated seriously. The conversion of benzene declined from 34.6% to 8% during 50 h, and the ethyl selectivity was 88%. While the benzene conversion of 2D HZSM-5 nano-sheet with same Si/Al atom ratio was stable at 44.0%, the ethyl selectivity reached to 94.8%, and the xylene selectivity reduced from 0.37% to 0.22%.
