Catalytic oxidative desulfurization of light gas oil over Keggin-type phosphomolybdic acid supported on TUD-1 metallosilicates

A facile one-pot synthesis was developed to produce a series of metal-substituted TUD-1 mesoporous (MTUD-1) supports. The synthesized supports, with nominal Si/M molar ratio of 40 (where M = Al, Zr, Fe, Cu, or Ce), were impregnated with 20 wt% heteropoly phosphomolybdic acid (HPMo) and applied for the catalytic oxidation desulfurization of light gas oil (LGO). Physicochemical properties of the supports and catalysts were characterized using techniques such as N2-sorption, TPD-NH3, FT-IR, XRD, XPS, and XANES. Powder XRD analyses of the catalysts confirmed the highly dispersed Mo Keggin ion particles on metal substituted TUD-1 supports that that of pristine TUD-1 support. The substitution of heteroatoms in the TUD-1 matrix was verified by FTIR and XPS. The heterogenized molybdenum heteropoly acid was found to retain its Keggin structure on TUD-1 supports. Catalytic oxidation desulfurization performances of the catalysts were evaluated with LGO in a stirred tank batch reactor. Among the catalysts, cerium substituted TUD-1 supported catalyst showed the highest oxidation activity to sulfur compounds of LGO. The oxidation activity of HPMo/CeTUD-1catalyst was optimized by varying the process conditions. Besides a catalyst, ODS of LGO required an oxidant. The efficiency of oxidants for ODS of LGO over HPMo/CeTUD-1 followed the order: cumene hydroperoxide > tert-butyl hydroperoxide > hydrogen peroxide > molecular oxygen. The ODS activity of heterogenized molybdenum heteropoly acid is promoted by the Lewis acidity of CeTUD-1.