介-微孔HZSM-5分子筛的制备及其性能评价

以NaOH溶液为后处理改性剂，制备了具有介-微孔结构的HZSM-5分子筛。采用XRD、XRF、NH3-TPD、SEM和N2等温吸附-脱附手段表征制备的介-微孔HZSM-5分子筛，并采用MAT-Ⅱ催化裂化微反装置考察其催化活性。结果表明，经不同浓度NaOH溶液处理HZSM-5分子筛，能够在保持分子筛微孔结构不减少的同时形成二次介孔，引起外比表面积和介孔体积增加，进而有效地调变其孔径分布。其中0.5 mol/L NaOH溶液处理的HZSM-5分子筛的外比表面积从107.6 m2/g增至192.3 m2/g，介孔体积由0.118 cm3/g增至0.226 cm3/g，轻油微反活性显著提高。介-微双孔道结构分子筛具有较大的比表面积和宽泛的孔径分布，从而促进了反应物、中间过渡态和产物分子在其孔道内的传质和扩散，有效地提高了分子筛的活性中心可接近性，显示出良好的催化性能。

Preparation and Performance Assessment of Meso-microporous HZSM-5 Zeolite

The meso-microporous HZSM-5 zeolite was prepared by post-modification of NaOH solution. The modified zeolite samples were characterized by means of X-ray diffraction(XRD), X-ray fluorescence(XRF), NH3 temperature-programmed desorption(NH3-TPD), scanning electron microscope(SEM), N2 adsorption-desorption. The catalytic activity of meso-microporous HZSM-5 was investigated by MAT-Ⅱcatalytic cracking equipment. The results suggested that after treatment by NaOH solution with certain concentration, the micropore of HZSM-5 zeolite remained, while secondary mesopore was produced, causing the external specific surface area and mesopore volume increased, so as to regulate its pore size distribution effectively. The external specific surface area of HZSM-5 sample treated by 0.5 mol/L NaOH was increased from 107.6 m2/g to 192.3 m2/g, and its mesopore volume was enlarged from 0.118 cm3/g to 0.226 cm3/g, with the significant increase of micro-activity to light oil. The larger specific surface area and wider pore size distribution of meso-microporous HZSM-5 zeolite can promote the mass transfer and diffusion of reactant, intermediate transition state and product molecules in its channels, improving the accessibility to active center of zeolites effectively and obtaining excellent catalytic performance.