Abstract
This chapter is aimed toward providing a general overview of the significant progress that desulfurization technology has brought to the oil and gas industries. Organosulfur compounds are known to release various environmentally harmful sulfur products into the atmosphere from the combustion engines of vehicles, leading to a serious environmental threat. Efficient removal of these sulfur compounds from diesel and gasoline fuels that we inevitably use in various capacities every day is therefore paramount. Various desulfurization technologies have been developed over the years to address this issue, and one of the most efficient and cost-effective approaches is transition metal-catalyzed hydrodesulfurization (HDS). Several nanocatalysts have been designed for this purpose. The chapter encapsulates some of the various ways in which these catalysts are being prepared, including doped nanocatalysts which are relatively unexplored for this application. It also includes a discussion and examples of their activities in the desulfurization reactions. The limitations are discussed, as well as possible ways to improve their sulfur removal efficiency. Furthermore, some of the commercially employed HDS catalysts, including feedstock, the reaction conditions they work best under, the type of reactor, and various factors affecting the hydrodesulfurization reactions are discussed, along with illustrations. The HDS mechanism is another important aspect of desulfurization that was thoroughly reviewed, including a discussion of the suggested pathways for the hydrodesulfurization of dibenzothiophenes (DBTs) and their derivatives, in addition to the toxic processes of HDS catalysts. Finally, the ongoing research on improved desulfurization processes, specifically the deep HDS of diesel and gasoline fuels in order to comply with the current standard for sulfur removal specifications, is also briefly addressed in this chapter.