Controllable synthesis of Bi2O3-MoO3 binary system metal composite oxides and structure–activity relationships for aerobic oxidative desulfurization

The deep removal of sulfide from fuel oil is the key to the production of clean energy using Bi2O3-MoO3 binary semiconductor materials that effectively improve the activity of the catalytic reaction. In this study, the controllable synthesis of Bi2O3-MoO3 binary metal composite oxides with different crystalline phases (α, β, and γ) was realized via microwave hydrothermal method at the pH of 1 through the variation of the theoretical Bi/Mo molar ratio. The catalytic oxidative desulfurization (ODS) experiments revealed that γ-Bi2MoO6 catalyst had higher catalytic activity than α-Bi2Mo3O12 and β-Bi2Mo2O9. At 65℃, γ-Bi2MoO6 catalyst exhibited the outstanding deep catalytic oxidation ability for dibenzothiophene (DBT), benzo thiophene (BT), and 4,6-dimethyldibenzothiophene (4,6-DMDBT). After 7 times of recycling, the removal rate of DBT still reached 99.11%. According to the kinetic fitting data, the catalytic oxidative desulfurization of DBT in model oil by γ-Bi2MoO6 conformed to the first-order kinetic equation with the reaction activation energy of 51.05 kJ/mol. Moreover, the possible mechanisms of ODS were explored. The ultrafast oxidation was concluded to be due to peroxo species produced through the action of composite metal oxides.