Abstract:

The surface properties of alumina support have been modified by introducing a heterogeneous carbon layer and doped boron by the method of carbon predeposition through precursor pyrolysis, with which the corresponding CoMo supported hydrodesulfurization (HDS) catalysts were then prepared. The physical-chemical properties of the modified Alumina and the series CoMo supported catalysts were characterized by using XRD, N₂-adsorption-desorption (BET), Py-FTIR, H₂-TPR, HRTEM, and XPS, and their HDS catalytic performance for the model compound DBT was assessed. The results showed that the introduction of carbon layer could effectively reduce the —OH functional group on the alumina support surface, and then regulate the acidity of alumina and the interaction between active metal and support (MSI), avoiding the formation of CoAl₂O₄ spinel. The doping of heteroatom B could produce more defect sites on the surface of the support, enhance the degrees of sulfidation and the dispersion of Mo species, and form more “Type Ⅱ” CoMoS active phase which was beneficial for the HDS of highly refractory organosulfur compounds. For DBT at 270℃ and 4,6-DMDBT at 290℃, with space velocity of 4h^-1, the HDS conversions on CoMo-Al₂O₃@BC reached 83.42% and 69.98%, respectively, which were 13.67% and 10.40% higher than those of CoMo-Al₂O₃ catalyst.

Key words: hydrodesulfurization, catalyst support, composites, alumina

摘要：

采用碳前体热解预积炭的方法，引入非均相碳层和杂原子硼对氧化铝载体表面性质进行改性掺杂，制备了相应的CoMo负载型加氢脱硫（HDS）催化剂。采用XRD、N₂-吸脱附（BET）、Py-FTIR、H₂-TPR、HRTEM和XPS等方法对改性氧化铝和CoMo系列负载催化剂进行物理化学性能表征，并对模型化合物DBT和4,6-DMDBT的HDS催化性能进行评价。分析结果表明：碳层的引入可以有效减少氧化铝载体表面的—OH官能团，进而调节氧化铝的酸性和调控活性金属与载体之间的相互作用，避免了CoAl₂O₄尖晶石的生成。杂原子B的掺杂可使得载体表面产生更多的缺陷位点，增强Mo物种的硫化程度和分散程度，活性金属在载体表面形成更多的“Type Ⅱ”型CoMoS活性相，这有利于复杂含硫化合物的加氢脱除。实验结果显示：270℃下DBT和290℃下4,6-DMDBT在CoMo-Al₂O₃@BC的催化剂上，重时体积空速为4h^-1条件下，HDS转化率最高，分别可达83.42%和69.98%，较CoMo-Al₂O₃催化剂分提升13.67%和10.40%。

关键词: 加氢脱硫, 催化剂载体, 复合材料, 氧化铝