Basic Research Of Ionic Liquids Strenthening Extraction Desulfurization Process With Lye From Mixed C₄

Mixed C4 is the main by-product of oil refineries,mainly including butene, butane and butadiene, mostly used as fuel in the past. Nowadays, we want to take advantage of butene and butadiene as chemical materials, making purification process essential, especially desulphurization and denitrification. Sulfides among mixed C4, consisting of hydrogen sulfide, mercaptan and sulfoether, are usually removed by Merox process. Procedures are that extract the sulfides, especially mercaptan, to lye above all, and then oxidate mercaptan, converting to disulfide. In the end, regenerate lye, as recycling extractant by reextraction.Ionic liquids, one kind of organic salt with low melting-point, own a number of unique properties. They have strong affinities with polar substances, furthermore, they are compatible with nonpolar substances. So they are effective additives for extraction. Strengthening chemical process by either physical means (enhancing stirring speed, adding heat transfer fins, adopting supergravity facilities) or chemical methods (adding extraction additives or entrainer), such as heat transfer, mass transfer (extraction), has been a hot spot in the research of chemical engineering in recent years.For the traditional extraction of mercaptan with lye have not show high efficiency yet, by adding ionic liquids into this system, it is likely to strengthen this process. As a result, suifide of mixed C4 would be extracted into lye phase efficiently.In this paper, different kinds of common ionic liquids were synthesized first of all. Then yields were calculated and structures were characterized. After comparing the desulphurizing capacity of lye with ionic liquids-lye as extracting agent, various univariate experiments, such as temperature, ratio of oil to extractant, stirring time and ionic types, were also carried out to explore the regularity inside. Therefore, [HMIM]Ac-NaOH, a system most suitable for industrial application tested, is chosen for optimizing experiment. It was proved that when the ratio of oil to extractant reaches 30:1, requirement of industry to take off the mercaptan would just be met under normal temperature and pressure. Eventually, related industrial design, including equipment selection and parameter calculating, was carried out according to experimental data. After all, this new process is certified to be feasible.