Application Of Hierarchically Macro-/Mesoporous Structured Metal Oxides To Hydrodesulfurization Of Thiophene And Benzothiophene

Hierarchically macro-/mesoporous structured Co-Mo-Ni/Al2O3, Co-Mo-Ni/TiO2-Al2O3 and CO-MO/Al2O3 catalysts were prepared by incipient wetness impregnation method, and applied to hydrodesulfurization of thiophene and benzothiophene. Catalyst characterization clearly showed that the as-prepared novel catalysts possessed monolithic macrochannels and the walls separating the macropores consisted of accessible mesopores. The hierarchically porous CO-MO-Ni/Al2O3 catalyst exhibited very similar intrinsic activities in thiophene hydrodesulfurization to the commercial Co-Mo-Ni/Al2O3 without the macroporous structure. However, when apparent activities were concerned, the former showed much higher activities than the latter, indicating the positive effect of the hierarchically porous structure on decreasing the internal diffusion of species in the catalyst. The addition of titanium into the support can decrease the interaction between active metal and support. When the titanium amount was relatively low (e.g.,28 wt%), the hierarchically porous Co-Mo-Ni/TiO2-Al2O3 catalyst displayed very high activities in thiophene hydrodesulfurization, no matter whether the catalyst was presulfided or not. However, more titanium in the support (e.g.,61 wt%) led to a sharp decrease in catalytic activities. The above results were further evidenced by rigorous kinetic investigations. Finally, the hierarchically porous CO-MO/Al2O3 catalyst exhibited much higher apparent activities in hydrodesulfurization of benzothiophene than the home-made CO-MO/Al2O3 without the macroporous structure, which further highlighted the diffusion-enhanced effect of the hierarchically macro-/mesoporous structure of the novel catalysts.