Ultra-deep oxidative desulfurization of fuel with H2O2 catalyzed by molybdenum oxide supported on alumina modified by Ca2+

Abstract

A highly active catalyst of molybdenum oxide supported on mesoporous alumina modified by Ca²⁺ was synthesized by an in situ method and applied in the catalytic oxidative desulfurization (CODS) system. This catalyst was characterized by FT-IR, XRD, BET and XPS. The influences of m(catalyst)/m(model oil), V(H₂O₂)/V(model oil), reaction temperature and reaction time on oxidative desulfurization of 4,6-dimethyldibenzothiophene (4,6-DMDBT), dibenzothiophene (DBT) and benzothiophene (BT) were investigated. This catalyst has high desulfurization activity in the removal of organic sulfides under mild conditions. The catalytic oxidation reactivity of sulfur-containing compounds is in the order of DBT > 4,6-DMDBT > BT. The kinetic studies reveal that the oxidative desulfurization of the organic sulfides can present a pseudo first-order kinetic process, and the apparent activation energies of 4,6-DMDBT, DBT and BT are 34.67 kJ mol⁻¹, 33.01 kJ mol⁻¹ and 40.16 kJ mol⁻¹, respectively. The recycling experiments indicate that 4,6-DMDBT, DBT and BT removal can still reach 90.0%, 89.9% and 87.3% after eight cycles.