The presence of elevated levels of sulfur in diesel oil results in an increased sulfur content in the process stream, which poses significant risks to human health, animals, the environment, vehicles, and infrastructure. Sulfur is a major contributor to particulate matter (PM) and total PM emissions. The level of pollutants emitted is correlated to the sulfur content in diesel fuel. Consequently, regulations regarding the sulfur content in crude oil products, particularly in diesel oil, have become increasingly stringent. Refiners are working to develop sulfur-free fuels with less than 10 ppm of sulfur. To address the impending threats to human health and the environment, and the impact of climate change on property, eco-friendly desulfurization techniques such as biodesulfurization (BDS) are being explored. Several bacterial species have been identified for the BDS of diesel oil, but extensive studies are needed to fully understand the mechanism. Further research on BDS is also required to make it more attractive and competitive in industrial applications. Combining BDS with other technologies for the desulfurization of diesel oil can potentially reduce operating costs and improve resource allocation, making this innovation a viable option for industry.

Desulfurization of fossil fuel derived oil is needed in order to comply with environmental regulations. Dibenzothiophene and benzothiophene are among the predominant sulfur compound present in raw diesel oil. In this study, mixing-assisted oxidative desulfurization of dibenzothiophene and benzothiophene were carried out using polyoxometalate/H2O2 systems and a phase transfer agent. The effects of reaction time (2–30 min) and temperature (30–70 °C) were examined in the oxidation of model sulfur compounds mixed in toluene. A pseudo first-order reaction kinetic model and the Arrhenius equation were utilized in order to evaluate the kinetic rate constant and activation energy of each catalyst tested in the desulfurization process. Results showed the order of catalytic activity and activation energy of the different polyoxometalate catalysts to be H3PW12O40 > H3PM12O40 > H4SiW12O40 for both dibenzothiophene and benzothiophene