ABSTRACT
Regulations have been introduced in both Europe and the United States with a view to reducing hazardous emissions from diesel motors by limiting the content of sulfur and aromatic compounds in diesel. In 1991, the Swedish Government proposed the introduction of three classes of diesel, each with a specific “energy tax”. The good fit to zero order kinetics suggests that the reaction is inhibited by adsorption of unconverted aromatics, and that the kinetics would be better represented by a Langmuir-Hinshelwood - Hougen-Watson type rate equation. The aromatics hydrogenation catalyst exhibits high activity at pressures typically used in diesel hydrodesulfurization units, which means that the second stage can be “added-on” and integrated into the existing desulfurization units. The purpose of the initial hydrotreating is to reduce the sulfur and nitrogen content in the diesel to a sufficiently low level to be able to achieve the required degree of aromatics removal in the aromatics hydrogenation section.
