Abstract: Hydrocracking catalyst for Fischer-Tropsch synthesis of wax was prepared by impregnation method with Ni/W metals on amorphous SiO2-Al2O3 support modified by USY sieve and characterized. The active phase and activity evaluation of sulfide catalyst were also studied. The results indicate that active metal components disperse on the support with high dispersion, and the catalyst with mesoporous structure has higher specific surface area and adsorption capacity. There exist three reduction peaks on the surface of catalyst at 340, 548 and 870℃, which represent NiO?Ni, W6+?W4+ and W4+?W2+ or W, respectively. Meanwhile, FT-IR spectra show that the species of NiWS, WS2 and NiSx exist on the surface of sulfide catalyst. The layer number of WS2 slabs is the important factor to determine the catalytic activity of catalyst. It is induced that alkene has higher hydrogenation activity. Alkane is cracked and isomerized to small molecule alkene, some of which may be in intermediate transition state for farther formation of the small molecule alkane during the hydrocracking and isomerization. At the reaction temperature of 370℃, pressure of 6.4 MPa, hydrogen/wax volume ratio of 800:1 and space velocity of 2.5 h-1, the wax conversion rate maintains almost 50%, and the diesel selectivity almost 90%. Ni/W metals supported on USY/SiO2-Al2O3 can obtain a relative balance of hydrogenation and cracking, thus the catalyst can assure higher wax conversion rate and diesel selectivity.

Key words: hydrocracking, catalyst, Fischer-Tropsch synthesis wax, active phase, selectivity

摘要： 以Ni/W为加氢活性组分，USY/SiO2-Al2O3为载体，采用浸渍法制备了费托合成蜡加氢裂化催化剂，对其进行了表征、活性相研究及活性评价. 结果表明，Ni/W以高分散度形式分散在催化剂载体上，催化剂具有比表面积较大、吸附能力强的中孔结构，在340, 548和870℃上有3个还原峰，分别对应NiO?Ni, W6+?W4+及W4+?W2+或W. 硫化态催化剂表面同时含NiWS, WS2和NiSx等活性相，WS2相片晶堆垛层数决定催化剂的活性. 烯烃具有较高的加氢反应活性，烷烃会裂化异构成小分子的烯烃，其中有的吸附态可能是进一步形成小分子烷烃过程中产生的中间过渡态. 在温度370℃、压力6.4 MPa、氢油体积流量比800、空速2.5 h-1的条件下，石蜡转化率约为50%，柴油的选择性约为90%. Ni/W均匀浸渍在USY/SiO2-Al2O3载体上，可获得相对均衡的加氢-裂解性能匹配，在不降低蜡转化率的同时保证了柴油的高选择性.

关键词: 加氢裂化, 催化剂, 费托合成蜡, 活性相, 选择性