Kinetic Models of Deep Hydrotreating Reactions to Produce Ultralow Sulfur Diesel

Due to the current worldwide environmental problems caused by high emissions of polluting gases such as CO, NOx, and SOx, resulting from the combustion of fossil fuels, many organizations and governments have established standards aimed at producing cleaner and more environmentally friendly fuels. These standards focus on eliminating hazardous substances, particularly the sulfur compounds in diesel, as they are among the most harmful organic compounds to both human health and the environment. Hydrotreating is the main refinery process used to produce ultralow sulfur diesel. For proper modeling and simulation of this process, it is mandatory to develop adequate kinetic models that include all the reactions taking place during the hydrotreating of gas oil, as well as the removal of the most refractory compounds present in the chemical composition of diesel, such as 4-MDBT and 4,6-DMDBT. This work reports an exhaustive discussion of the kinetic models of hydrotreating reactions for the production of ultralow sulfur diesel reported so far in the literature. The main topics include the reaction systems, type of catalysts, and operating conditions. A comparison of the reported kinetic parameters was also carried out. Finally, a set of kinetic models to be considered for the simulation of the hydrotreating process to produce ultralow sulfur diesel is proposed.