MCM-22和ITQ-2分子筛负载型催化剂加氢裂化性能的对比研究

Comparative Study on Hydrocracking over MCM-22 and ITQ-2 Zeolite-Supported Catalysts

以MCM-22和ITQ-2分子筛为载体,WNi为活性组分,制得两种负载型催化剂,考察了两种催化剂的加氢裂化性能,并通过N2吸附、氨程序升温脱附和原位红外光谱对催化剂进行了表征.减压瓦斯油加氢裂化反应结果表明,WNi/ITQ-2的加氢裂化活性高于WNi/MCM-22,并且前者的反应温度相对较低.WNi/ITQ-2具有高催化活性是因为ITQ-2分子筛具有空旷的次级结构和较多的可接近的酸性位;中油选择性高是因为空旷的次级结构使裂化产物快速离开酸性位而避免了二次裂化.

A series of supported WNi catalysts for hydrocracking of vacuum gas oil （VGO） were prepared using ITQ-2 and MCM-22 zeolites as supports. The catalysts were characterized by temperature-programmed desorption of ammonia, infrared spectroscopy of pyridine adsorption, and nitrogen adsorption. The acidities of WNi/ MCM-22 and WNi/ITQ-2 catalysts were similar; but the surface area and pore volume of WNi/ITQ-2 were larger than those of WNi/MCM-22. The results of VGO hydrocracking indicated that WNi/ITQ-2 catalysts had higher catalytic activity and selectivity for middle distillates. The higher activity was due to the large secondary pore structure of the ITQ-2 zeolite and its rich accessible acidic centers. The reason for the higher selectivity was that products left acid centers rapidly and secondary cracking was avoided because of the large secondary structure.