New insights on oxidative desulfurization for low sulfur residual oil production

Abstract

Combustion of heavy fuel oils releases sulfur oxides (SO_x) which are known to cause various types of diseases which are harmful to human health, and also contribute to acid rain. The International Maritime Organization (IMO) regulations to reduce emission of SO_x from ships came into force in 2005. With the new regulation in force, from 1st January 2020 (IMO-2020) the upper limit of sulfur in fuel oil used in ships operating outside designated emission control areas is now restricted to 0.5 wt%. Currently, installation of scrubbers, catastrophic blending and hydrodesulfurization are some of the techniques available to the shipping industries to reduce the sulfur content and meet the specifications of IMO-2020 grade residual oil. However, the high capital cost for scrubber installation, demand for use of higher temperature/pressure and hydrogen consumption in hydrodesulfurization are some of the intrinsic drawbacks. In this regard, oxidative desulfurization (ODS) could be a solution to produce IMO-2020 grade residual oil. Herein, we present for the first time, a systematic evaluation and new insights to produce IMO-2020 compliant residual oil using a heterogeneous catalyst system together with a techno-economic evaluation. The V₂O₅/Al₂O₃ heterogeneous catalyst was used in combination with cumene hydroperoxide (CHP) to desulfurize residual oil at atmospheric pressure. The ability to recycle CHP makes the ODS process economically viable, and a potential competitor to the currently existing processes being used, to produce IMO-2020 compliant residual oil. This systematic study, gives new insights and the techno-economic evaluation shows the potential of ODS to produce IMO-2020 compliant residual oil for the shipping industries and this study could be utilized for future developmental purposes.