微波辅助制备Ni-W-P/γ-Al2O3煤焦油加氢催化剂

采用微波辅助浸渍法、微波管式焙烧制备了Ni-W-P/γ-Al₂O₃催化剂,并以中低温煤焦油轻油为原料,在固定床反应器装置上评价了催化剂的加氢活性。通过N₂吸附-脱附、GC-MS等方法对催化剂的物化性能及加氢产物油进行表征,并根据FHH模型,计算出催化剂的表面分形维数。结果表明,添加助剂P可调节催化剂的微观孔结构,改变催化剂的酸性分布与强度,并有助于加氢饱和反应的进行;当助剂P含量为0.9%时,催化剂的加氢脱硫、脱氮活性最高,加氢饱和性能最好;焙烧温度直接影响催化剂物性参数,当温度为500 ℃时,加氢活性最高、加氢产物品质最佳;微波焙烧相比常规制备方法,可增加晶粒烧结程度,形成更多三维孔隙结构,为加氢反应提供更大的表面和空间,且增加中等强度酸的酸量,更有助于表面活性组分的分散及硫化性的增强。

Microwave-assisted preparation of Ni-W-P/γ-Al2O3 catalyst for coal tar hydrogenation

Ni-W-P/γ-Al₂O₃ catalyst was prepared through microwave-assisted impregnation and calcination in microwave tube oven,tested hydrogenation activity in a fixed-bed reactor using middle/low temperature coal tar light oil as raw material.Physical property of the catalyst and hydrogenation products were characterized by N₂ adsorption-desorption ,GC-MS and so on.The surface fractal dimension of catalyst was calculated by full adsorption data according to the FHH model.The results show that P addition can adjust pore structure of catalyst,alter acid strength and site distributions,and improve catalytic performance.Hydrodesulfurization(HDS)and hydrodenitrogenation(HDN) activities of the catalyst are the highest at P content of 0.9%,while activity of hydrosaturation is also the best.Calcination temperature has direct effect on physical property of the catalyst,and hydrogenation activity and product quality are best at 500 ℃. Compared with catalysts prepared by conventional methods,catalysts prepared by microwave-assisted calcinations has higher degree of grain sintering,more three-dimensional pore structure,larger surface and space for hydrogenation,more medium acid site,higher dispersion of active components and vulcanization.