Comparative Studies on the Bio-desulfurization of Crude Oil with Other Desulfurization Techniques and Deep Desulfurization through Integrated Processes

With an increase in environmental degradation, the environmental norms are becoming more and more stringent day by day. Research work is currently being undertaken around the world to bring about deeper desulfurization of crude oils. Presently, two crude oil samples, i.e., heavy crude oil (HCO, 1.88% S) and light crude oil (LCO, 0.378% S) were procured from a local petroleum refinery. Bio-desulfurization (BDS) of LCO using Pantoea agglomerans D23W3 resulted in 61.40% removal of sulfur, whereas HCO showed 63.29% S removal under similar conditions. The use of P. agglomerans D23W3 under anaerobic conditions showed marginally better results than those under aerobic conditions. However, the use of thermophile Klebsiella sp. 13T resulted in 62.43% S removal from LCO and 68.08% S removal from HCO. Studies have also been extended on the use of reactive adsorption techniques for the removal of sulfur from crude oils. Among all of the different adsorbents studied, residual coal obtained after the solvent extraction of Samla coal showed the maximum removal of sulfur, i.e., 78.90% from LCO and 74.46% from HCO. Hydro-desulfurization is an established technology for the deep desulfurization of petroleum and its products. Widening the choice and exploring further developments in deeper desulfurization of petroleum alternative technologies may also be developed. Comparative studies were extended on the use of BDS, reactive adsorption, oxy-desulfurization, photo-desulfurization, and solvent extraction for the removal of sulfur from HCO and LCO. Among all of these techniques, oxy-desulfurization was found to be the best. To study the deep desulfurization of LCO and HCO, two- and three-step integrated processes were developed for the removal of sulfur from HCO and LCO. BDS under anaerobic conditions followed by oxy-desulfurization followed by reactive adsorption integration resulted in maximum removal, i.e., 95.21% removal of sulfur from HCO and 94.30% removal of sulfur from LCO.