Applicable Basic Study On Desulfurization Of Light Oil By Fiber Film Process

Fiber film technology has its unique advantages in light oil desulfurization processes, but the technology has some shortages, such as the use of untreated chromium-nickel alloys fibers results in high cost and poor surface hydrophilicity; cobalt sulfophthalocyanine(CoSPc) in caustic solution is instable; the products distribution of S2- oxidation in the successive extraction-oxidation process was hardly ever studied.For the above shortcomings, this paper launched a systematic study from the aspects of improving corrosion resistance and surface hydrophilicity of stainless steel, improving stability of CoSPc caustic solution, and exploring the oxidation of sulfides in CoSPc caustic solution, obtained corresponding conclusions, which will lay the theory foundation for the progress of fiber film desulfurization technology.For the first time, the surface modification method—stainless steel surface conversion film technology was developed, which can effectively improve corrosion resistance and surface hydrophilicity of stainless steel. The optimum treatment conditions of the stainless steel surface conversion film technology were obtained. The results showed that the stainless steel surface conversion film technology may effectively improve the corrosion resistance of stainless steel, and the stainless steel surface conversion film has good thermal expansion, impact resistance and ductility, and it is stable in most commonly industry medium and CoSPc caustic solution, and can play a good role in the protection of stainless steel; the stainless steel surface conversion film technology can significantly improve surface hydrophilicity of materials, and the stainless steel surface conversion film can retain good and stable hydrophilicity in water and caustic environments. Therefore, the technology can be used for treating stainless steel fiber of a fiber film reactor to increase its desulfurization efficiency and operating life.The surface morphology and structure of stainless steel before and after treatment were analysed to explore the mechanism of the stainless steel surface conversion film improving material corrosion resistance and surface hydrophility. The results showed that the stainless steel surface conversion film thickness increases, surface defects decrease, contents of Cr, O increase, thereby the corrosion resistance is significantly improved; surface tension and adhesion work increase, surface oxygen-containing polar groups increase significantly, surface organic pollutions removal, so the surface hydrophilicity of stainless steel is effectively improved.The study on the stability and activity of CoSPc caustic solution found influence factors of the solution stability and the unstability cause of CoSPc caustic solution at various conditions. The effect of a composite activator ST on CoSPc caustic solution stability was investigated. The results showed that ST can effectively improve the stability of CoSPc caustic solution under different conditions, and can extend cycle life of the solution. The stability mechanism of its was also proposed.Influence factors and oxidation products distribution of S2- oxidation was investigated, and it can be concluded that main oxidation products of S2- are S2O32- and sulfur under experiment conditions, and conversion of S2- and yield of S2O32- increase with increasing of oxidation temperature, oxidation time and content of oxygen. Successive extraction - oxidation was adopted to simulate fiber film sweetening process for studying conversion of S2- and RS- in the process, and the deep oxidation conditions of S2- were discussed. The results showed that conversion of S2- and RS- decreases with increase of extraction-oxidation cycles, while content of sulfur and S2O32- increases in the process, and sulfur in CoSPc caustic solution can dissolves in gasoline drawn for next extracion, which aggravates copper corrosion level of gasoline; higher oxidation temperature and longer oxidation time are favorable to oxidation process of S2- into S2O32-. These conclusions can offer theory support for promoting the deep oxidation of S2- and decreaseing light oil corrosion in fiber film desulphurization process.At present, some results of the studty have been adopted in developing a fiber film reactor and corresponding LPG fiber film desulfurization processes. It has been practically testified that the technology has preferable desulfurization efficiency and a broad prospect of application.