Oil desulfurization

Oil desulfurization is a widely used method for reducing sulfur dioxideand particulate (smoke) emissionsfrom automobiles, trucks and other internal combustion engines and oil-burning power plants. Typically, oil is desulfurized in refineries using a process, referred to as Hydrodesulfurization (HDS), involving the reaction of hydrogenwith oil in the presence of a catalyst at high temperature, resulting in the removal of sulfur in the form of hydrogen sulfidegas.

The effectiveness of HDS is determined by the type of catalyst employed, typically a catalyst containing transition metals such as Cobalt and Molybdenum, and the severity of the reactor conditions, notably, temperature, hydrogen pressure and residence time. In general the better the catalyst and the more severe the conditions the more desulfurization occurs in a given time period.

An alternative to conventional HDS has been developed using the enzymes of microorganisms as the catalysts for sulfur removal, referred to as biological desulfurization or BDS. Interestingly, dibenzothiophene sulfur compounds are typically the most susceptible to BDS, yet, in contrast, are the most resistant to HDS. The removal of these molecules can add significantly to refinery costs for the production of the low sulfur fuels mandated by current and pending EPA regulations.

This process has not yet been commercially practiced largely to due to process cost issues arising from low catalytic rate and longevity. Energy BioSystems (now Enchira) was a company dedicated to the development of this technology. Research in this area continues in various locations around the world.

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It uses material from the http://en.wikipedia.org/wiki/Oil+desulfurization Wikipedia article Oil desulfurization.