Highly Active Sulfided NiPMo Hydrodesulfurization Catalyst Prepared from Keggin-type Phosphomolybdic Acid

A highly active sulfided NiPMo/MCM-41 (NiPMo-S/M41) hydrodesulfurization (HDS) catalyst was successfully synthesized using Keggin-type phosphomolybdic acid as the phosphorus and molybdenum source and thioacetamide as the sulfur source. The supported catalysts NiPMo/M41, Ni2P-Mo/M41, and Ni2P/M41 were also prepared to investigate the effects of Mo, S, and the Keggin structure on the HDS performance. The HDS activities of NiPMo/M41 and NiPMo-S/M41 toward dibenzothiophene were much higher than that of Ni2P-Mo/M41, demonstrating that the active phases in the Kegginstructured catalysts were significantly superior to the Mo-modified Ni2P phase. The HDS activities of the catalysts followed the order NiPMo-S/M41 (96.7%) > NiPMo/M41 (89.9%) > Ni2P-Mo/M41 (53.5%) > Ni2P/M41 (48.9%). For Ni2P/M41, Ni2P-Mo/M41, and NiPMo/M41, cyclohexylbenzene (CHB) was formed in low concentrations (<21.0%), indicating that direct desulfurization was the favored reaction route and that this did not change for Keggin-structured NiPMo/M41. By contrast, the CHB selectivity of NiPMo-S/M41 increased to 44.6%, much higher than that of NiPMo/M41 (17.6%), demonstrating that sulfidation enhanced the hydrogenation ability, which was ascribed to a metal-acid synergistic effect.