Ni2P/SBA-15催化剂的结构及加氢脱硫性能

以硝酸镍为镍源, 磷酸氢二铵为磷源, 介孔分子筛SBA-15为载体, 用共浸渍法制备了含磷化镍前驱体的样品, 然后在氢气流中采用程序升温还原法, 制备了Ni2P质量分数为5%-40%的Ni2P/SBA-15催化剂. 用X射线衍射(XRD)、N2吸附脱附、透射电子显微镜(TEM)、傅立叶变换红外光谱(FTIR)等分析测试技术对催化剂的结构进行了表征, 以噻吩和二苯并噻吩(DBT)为模型化合物, 在微型固定床反应器上对催化剂的加氢脱硫(HDS)性能进行了评价. 结果表明, Ni2P/SBA-15催化剂中SBA-15 的介孔结构依然存在, 活性组分Ni2P具有良好的分散性, 但随Ni2P含量的增加, 催化剂的比表面积、孔容和孔径均有明显减小. 当反应温度为320 ℃时, Ni2P含量为15%-25%(w)的催化剂就具有很好的加氢脱硫催化性能; 反应温度在360 ℃以上时, 所有催化剂都具有优异的深度脱硫催化性能. Ni2P/SBA-15催化剂对二苯并噻吩的加氢脱硫(HDS)主要以直接脱硫机理(DDS)进行.

Structure and Hydrodesulfurization Performances of Ni2P/SBA-15 Catalysts

The samples containing nickel phosphide precursors were synthesized by co-impregnation method using mesoporous molecular sieve SBA-15 as support, nickel nitrate as nickel source, and (NH4)2HPO4 as phosphorus source. Then, the Ni2P/SBA-15 catalysts with different Ni2P contents were prepared by temperature-programmed reduction method in H2 flow. The structure of the catalysts was characterized using X-ray diffraction (XRD), N2 adsorption/desorption, transmission electron microscopy (TEM), and Fourier transform infrared (FTIR) techniques. The catalytic performances of hydrodesulfurization (HDS) were evaluated in a fixed-bed micro-reactor using thiophene and dibenzothiophene (DBT) as the model compounds. The results indicated that the mesoporous structure of SBA-15 was still preserved in the Ni2P/SBA-15 catalysts. The active component Ni2P was well dispersed on the surface of the catalysts. The BET surface area, pore volume, and pore diameter decreased obviously with the increase of Ni2P loading. The Ni2P/SBA-15 catalysts had the better catalytic performance at 320 ℃ when Ni2P loading was from 15% to 25% (w, mass fraction) . All of the catalysts showed an excellent deep HDS performance when reaction temperature was higher than 360 ℃. The mechanism of the HDS of DBT was the main direct desulfurization (DDS) over the Ni2P/SBA-15 catalysts.