Hydrodesulfurization of hindered dibenzothiophenes: an overview

Hydrodesulfurization is a well-documented process which has been commonly used in the refining of crude oil for over 60 years. It is a process for which interest is frequently renewed due to the requirement to use new feedstocks and the application of more severe environmental legislation, for example, the need to reduce sulfur levels in fuels. Of particular importance in achieving low sulfur levels in fuels is the problem posed by a particular class of compounds, namely hindered dibenzothiophenes, e.g. dibenzothiophene, 3-methyldibenzothiophene and 4,6-dimethyldibenzothiophene. Dibenzothiophenes demonstrate resilience to hydrodesulfurization using current catalyst formulations. This overview addresses the key area of hydrodesulfurization chemistry concerning the desulfurization of highly hindered sulfur containing molecules. (C) 2000 Elsevier Science B.V. All rights reserved.