Synthesis, Characterization, and Catalytic Performances of Novel CoMo Hydrodesulfurization Catalysts Supported on Mesoporous Aluminas

A series of mesoporous aluminas of different morphologies was prepared using synthesis methods recently described in the literature. These aluminas were used as supports for CoMo HDS catalysts that were fully characterized. Their performances were evaluated using an atmospheric thiophene HDS catalytic test. The proper-ties of the mesostructured alumina-based catalysts were compared with those of a conventional alumina-based CoMo catalyst and of a previously optimized sol-gel alumina-based catalyst (reference aluminas). The highest conversion was observed when using the alumina prepared from Al-sec-butoxide with P123 as a templating agent, which exhibited the largest mesopores and a fine fibrillar morphology, with a result ca. 25% larger than that observed on both reference aluminas. According to their catalytic behavior, the samples were divided into two groups, the first one comprising the low conversion catalysts, and the second one comprising the high conversion catalysts. Among all the considered parameters (physical properties of the solids, oxidic phase nature, sulfidic phase morphology), only the difference in the state of the oxo-molybdate phase gave a reliable correlation with catalytic performances. In the oxidic form, the low activity samples presented monomolybate species, whereas the high activity samples presented polymolybdate, species.