【摘要】 考察了氮气预处理温度对硫代硫酸铵预硫化的Mo/Al2O3催化剂噻吩加氢脱硫(HDS)活性的影响.采用X射线衍射、高分辨电镜、光电子能谱、热重质谱和硫分析等方法对催化剂进行了表征.结果表明,预硫化催化剂经80℃低温处理并于200℃氢气原位活化后噻吩转化率达到最高.对于氮气低温预处理或常温干燥的预硫化催化剂,载体氧化铝被硫酸根修饰,减少了Mo与载体的相互作用,使得催化剂活化后硫化程度高,MoS2活性相呈多层的Ⅱ型结构,因而HDS活性高.高于200℃的氮气热处理造成硫代硫酸铵的分解,并有少量的多层MoS2活性相生成,但高温热处理造成硫的流失使得活性金属活化后硫化程度偏低,而且MoS2活性相呈现单层的Ⅰ型结构,因而HDS活性较低.更多还原

【Abstract】 A series of Mo/Al2O3 catalysts were presulfidized with (NH4)2S2O3 aqueous solution, dried at ambient temperature, and thermally treated in N2 flow. The catalysts were characterized by X-ray diffraction, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, thermogravimetry-mass spectrometry, and sulfur analysis. Thermal pretreatment in N2 had a significant effect on the catalytic performance of the (NH4)2S2O3-presulfidized Mo/Al2O3 for the hydrodesulfurization (HDS) of thiophene. The sample pretreated at 80 ℃ in N2 flow and activated at 200 ℃ in H2 gave the highest thiophene conversion. This is due to that the modification of the Al2O3 support by sulfate ions weakened the interaction of Mo species with the support, which increased its sulfidization to form a highly active multilayer Type Ⅱ MoS2 structure. In contrast, N2 thermal treatment above 200 ℃ led to the decomposition of (NH4)2S2O3 and decreased the sulfiding degree, which resulted in the formation of a less active single layer Type Ⅰ MoS2 structure with a low activity for thiophene HDS.更多还原