On Stability of High-Surface-Area Al2O3, TiO2, SiO2-Al2O3, and Activated Carbon Supports during Preparation of NiMo Sulfide Catalysts for Parallel Deoxygenation of Octanoic Acid and Hydrodesulfurization of 1-Benzothiophene

Abstract

NiMo sulfide catalysts were prepared by the impregnation of high surface area supports with an aqueous solution made of NiCO3·2Ni(OH)2, MoO3 and citric acid, followed by freeze drying and sulfidation in H2S/H2 mixture. N2 physisorption and X-ray diffraction were selected to investigate the amphoteric oxides Al2O3 and TiO2, acidic SiO2-Al2O3 and activated carbon supports, fresh prepared sulfide NiMo catalysts and spent catalysts after model parallel reaction of octanoic acid deoxygenation and 1-benzothiophene hydrodesulfurization. The studied mesoporous amphoteric oxides Al2O3 and TiO2 did not lead to highly active NiMo catalysts due to the low hydrothermal stability of these supports during the preparation of the active sulfide phase and deoxygenation reaction. The most active catalyst based on oxidic support was the NiMo sulfide supported on acidic mesoporous SiO2-Al2O3, which was explained by the increased stability of this support to the water and CO/CO2 mixture during the activation of the sulfidic phase and deoxygenation reaction. The extraordinarily high stability of the activated carbon support led to outstanding activities of the sulfidic NiMo/C catalyst.