Insight into oxygen vacancies roles and reaction mechanism of PMoA-TiO2-M catalyst on deep oxidative desulfurization of fuel oil

DFT calculation simulation path of dibenzothiophene oxidative desulfurization. • A novel mesoporous PMoA-TiO 2 -M catalyst was synthesized by one-step method. • DFT modeling verified the role of oxygen vacancy in the ODS reaction. • APPI FT-ICR MS and NMR characterized the distribution of the organosulfur compound. • ODS reaction order follows DBT > BT > 4,6-DMDBT. • The catalytic mechanism of DBT oxidative desulfurization is summarized. Oxidative desulfurization (ODS) technology has attracted increasing attention as a practical approach for producing cleaner fuel oil. This study synthesized a novel phosphomolybdic acid (PMoA) based mesoporous catalyst with a high density of oxygen vacancies using a facile one-pot method. The role of oxygen vacancies in the ODS mechanism was detailed and proposed through density functional theory (DFT) simulation. The ODS catalytic performance of different model oil compounds over the series of catalysts was systematically evaluated. Remarkably, dibenzothiophene (DBT) achieved a desulfurization efficiency of 99.5% within 10 min at 60 °C and an O/S ratio of 3 in a batch reactor using hydrogen peroxide (H 2 O 2 ) as the oxidant. The ODS reactivity order followed DBT > BT (benzothiophene) > 4,6-DMDBT (4,6-Dimethyldibenzothiophene). Furthermore, the ODS of Arabian Extra Light oil (AXL) was investigated under optimized conditions using an extraction-adsorption process. Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS) and Nuclear Magnetic Resonance (NMR) results revealed that O 2 S and O 2 S 2 species with lower carbon numbers (<30) can be easily separated due to their higher polarity property for the AXL ODS experiment. DFT results confirmed that oxygen vacancies significantly enhance H 2 O 2 adsorption, thereby improving the efficiency of the ODS process. This study provides theoretical insights into the rational design of ODS catalysts and demonstrates that the synthesized catalyst is a promising candidate for industrial ODS applications.