Oxidative desulfurization of dibenzothiophene over highly dispersed Mo-doped graphitic carbon nitride

Mo-doped graphitic carbon nitride (Mo/g-C3N4) was successfully prepared by thermal condensation of a Mo/melamine precursor in a semi-closed alumina crucible at 550 degrees C without atmosphere. Thermogravimetric analysis (TGA) was used to evaluate the polymerization route of the precursor, and theoretical and experimental investigations revealed that the Mo species were likely dispersed and anchored to the pyridinic groups of g-C3N4. As a result, the obtained Mo/g-C3N4 displayed exceptional catalytic activity in the oxidative desulfurization of dibenzothiophene (DBT) with H2O2. The effects of catalyst dosage, O/S ratio, and temperature on the catalytic properties of Mo/g-C3N4 were investigated. The kinetic studies revealed a pseudo-first-order kinetic process for DBT oxidation with an apparent activation energy of 43.6 kJ mol(-1). Experimental and theoretical evaluation of the Mo/g-C3N4 stability suggests that catalytically active Mo species are progressively leached from the g-C3N4 structure. The decrease in the Mo-N bond order after forming reactive peroxo-Mo(VI) groups was associated with catalyst deactivation.

Automated summary

In this study, Mo-doped graphitic carbon nitride was successfully prepared and exhibited exceptional catalytic activity in the oxidative desulfurization reaction. The catalytic properties of Mo/g-C3N4 were influenced by catalyst dosage, O/S ratio, and temperature. Kinetic studies showed a pseudo-first-order reaction with a low apparent activation energy for DBT oxidation. Additionally, the Mo/g-C3N4 catalyst exhibited poor stability as catalytically active Mo species were leached from the catalyst structure, leading to catalyst deactivation.