乙醇辅助的化学沉积法制备硫化型Mo/γ-Al2O3加氢脱硫催化剂

以硫代乙酰胺为硫源,钼酸钠为钼源,乙醇为分散剂,采用化学沉积法制备了MoS₃/Al₂O₃催化剂前驱体,再用H₂高温处理得到高分散硫化型MoS₂/γ-Al₂O₃催化剂,运用N₂吸附-脱附、X射线光电子能谱以及高分辨透射电子显微镜等技术对MoS₂/γ-Al₂O₃催化剂进行了表征,并以二苯并噻吩作为模型化合物评价了催化剂的加氢脱硫(HDS)活性.结果表明,与浸渍法相比,所制催化剂具有更大的比表面积和孔体积、更高的活性金属分散度、更佳的Mo物种硫化度以及更短的MoS₂片层长度和更高的堆积度,因而在二苯并噻吩HDS反应中表现出远优于浸渍法所制催化剂的活性.乙醇可通过S?H-O氢键吸附至MoS₃纳米粒子表面,可有效防止其生长和团聚,起到分散剂的作用.

Sulfided Mo/Al2O3 hydrodesulfurization catalyst prepared by ethanol-assisted chemical deposition method

In this communication, we report a novel strategy to prepare a MoS₂/Al₂O₃ hydrodesulfurization (HDS) catalyst by thermally treating a MoS₃/Al₂O₃ precursor in H₂ atmosphere. In our approach, the active phase precursor MoS₃ was first prepared using thioacetamide and sodium molybdate as sources of S and Mo, respectively, and ethanol as a dispersant. The precursor was deposited onto the surface of a γ-Al₂O₃ support and heat-treated to form the catalyst. The catalyst was characterized by N₂ adsorption-desorption, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy. The HDS activity of the catalyst was assessed using dibenzothiophene as a model reactant. The catalyst possessed larger specific surface area and pore volume, higher dispersion and degree of sulfidation of Mo species, and shorter and more suitable stacking of MoS₂ slabs, resulting in superior catalytic activity compared with a catalyst with the same metal content prepared by the conventional impregnation method. Ethanol could disperse the precursor MoS₃ particles via “S…H-O” H-bonding to lessen their aggregation.