机械化学法制备的Al/Ce复合氧化物负载NiMo催化剂的加氢脱硫活性(英文)

将Al和/或Ce的硝酸盐与NH_4HCO_3球磨混合,采用机械化学法制备了Al_2O_3-CeO_2载体(其中Ce含量为1-10 wt%),再以杂多钼酸盐(NH_4)_4NiMo_6O_(24)为活性金属Ni和Mo的前驱体,通过浸渍法制备NiMo_6/Al_2O_3-CeO_2催化剂,并将其用于1-苯并噻吩(BT)的加氢脱硫(HDS)反应中.运用化学分析、X射线衍射、N_2吸附-脱附法、H_2程序升温还原、NH_3程序升温脱附和X射线光电子能谱对催化剂的物化性质进行了表征.结果表明,催化剂的酸性随着载体中Ce含量的增加而下降.Ce修饰的Al_2O_3载体表面的NiS/MoS原子比下降了2倍.NiMo_6/Al_2O_3催化剂表现出最高的HDS活性(以单位重量催化剂计),其酸性和表面MoO_xS_y物种的浓度(Mo~(5+)浓度)也最高;当催化剂中Ce含量逐渐增加到10 wt%以上时,其活性逐渐将为0.与浸渍法制得的参比催化剂相比,前驱体和催化剂组成相同的情况下,采用机械化学法制得的所有催化剂活性明显提高.

Hydrodesulfurization activities of NiMo catalysts supported on mechanochemically prepared Al-Ce mixed oxides

Al2O3‐CeO2 supports containing 1–10 wt%Ce were prepared mechanochemically by milling alumi‐num and/or cerium nitrates with NH4HCO3. Heteropolymolybdate, (NH4)4NiMo6O24, was used as the precursor of the Ni and Mo to prepare NiMo6/Al2O3‐CeO2 components in catalysts by impregnation method. The physicochemical properties of the catalysts were determined using chemical analysis, X‐ray diffraction, temperature‐programmed H2 reduction, temperature‐programmed NH3 desorp‐tion, X‐ray photoelectron spectroscopy (XPS), and the Brunauer–Emmett–Teller method. The cata‐lyst acidity decreased with increasing Ce concentration in the support. XPS showed that the NiS/MoS ratio decreased two‐fold for the Ce‐modified alumina support. NiMo6/Al2O3, which had the highest acidity, showed the highest activity in hydrodesulfurization of 1‐benzothiophene (normal‐ized per weight of catalyst). The concentration of surface MoOxSy species (which is equal to the con‐centration of Mo5+) gradually decreased to zero for catalysts with Ce concentrations 3 10 wt%. However, the activities of all the catalysts prepared mechanochemically from Al2O3 and Al2O3‐CeO2 supports significantly exceeded that of a reference NiMo6/Al2O3 catalyst prepared by impregnation method using the same precursor and with the same composition.