A review of advanced methods for ultra-deep desulfurization under mild conditions and the absence of hydrogen

The amount of sulfur in crude oil has become a global concern because high levels of sulfur in refinery streams cause catalysts to become inactive and refinery equipment to corrode. Also, the sulfur in the fuel of vehicles leads to the release of undesirable gases and acid rain. Therefore, the refinery must be able to remove sulfur from crude oil. The hydrodesulfurization process is one of the common methods for removing sulfur. Due to costly technical challenges to eliminate sulfur compounds and reduce octane number during this process, new technologies have been developed as complementary methods. Although various methods for complementary desulfurization have been introduced in the articles, few of these methods are used on a large scale. The reason for this is the lack of knowledge of the advantages and disadvantages of each method, which is an obstacle to their development. Therefore, articles to fully understand each technique can open the way for development and implementation in the industry.