AM-99-27 "Recent Advances In Biodesulfurization Of Diesel Fuel"

Description:

Energy BioSystems Corp. (EBC) is developing a unique refinery process using bacteria to selectively remove sulfur from diesel and diesel blend stocks. The process operates at ambient temperature and pressure and uses air instead of hydrogen to remove the sulfur. The biocatalyst for the process has been genetically engineered to have a high level of enzymatic activity for the selective oxidation of sulfur in diesel fuel and to produce a water-soluble organic sulfonate product. The process design has been changed recently to maximize the rate of sulfur removal in the bioreactors, thereby reducing capital cost; produce and regenerate the catalyst within the actual biodesulfurization (BDS) process, thereby reducing catalyst cost; and recover a valuable organic sulfonate commodity, thereby generating a significant potential revenue stream from the products of the iodesulfurization chemistry. The feedstock to EBC’s new process can be any refinery diesel stream that contains a relatively high concentration of polynuclear aromatic sulfur heterocyclic compounds. The process is suitable for treating LCCO, LCSGO, HS-HMD or the product of a diesel hydrotreater. The process can be used instead of conventional hydrodesulfurization (HDS), but it also provides considerable synergy with HDS. Upstream of an HDS unit, the technology can produce a very profitable yield of the organic sulfonate commodity and improve the performance of the downstream diesel hydrotreater. Downstream of an HDS unit, the technology removes the residual dibenzothiophenes left behind by the hydrotreater and provides a low-sulfur product with improved lubricity and oxidation stability. Recent advances in BDS process technology are described and illustrated with results from a wide variety of refinery diesel streams. Examples of surfactant products from diesel BDS are included, along with limited information on process economics. Finally, the status of EBC’s first commercial BDS project in Valdez, Alaska, is briefly reviewed.