Study On Deep Non-Hydrodesulfurization Of Refined Diesel

With increasingly strict standard of sulfur content and growth of market demand for clean diesel, deep desulfurization technology of diesel has been widely concerned. Catalytic oxidative desulfurization and adsorptive desulfurization can be considered as supplement for hydrodesulfurization process to achieve deep desulfurization of refined diesel, and make total sulfur content less than lOppm. Composition and distribution of organic sulfides in hydro fining diesel were analyzed; influence of deep desulfurization performance by oxidation with H2O2/HCOOH/heteropolyacid system, the reinforcement of ultrasonic, the process conditions and the composition of catalytic system were investigated; deep desulfurization performance of modified activated carbon, adsorption thermodynamics and adsorption selectivity of DBTs were studied.Experimental results showed that, in oxidative desulfurization process, main organic sulfides in refined diesel included4-MDBT,4,6-DMDBT,3,6-DMDBT,4E,6-MDBT,2,4,6-TMDBT and1,4,6-TMDBT. Ultrasonic could significantly increase the oxidative desulfurization rate, when dosage of heteropolyacid was0.2%, O/S molar ratio was10:1, concentration of HCOOH was80%, oil and water volume ratio was5:1, reaction temperature was80℃, ultrasonic time was25min, ultrasonic power was320W, and dilution ratio was2, process conditions were optimized and total sulfur removal reached more than97%; oxidative order of DBTs was4-MDBT>3,6-DMDBT>4,6-DMDBT≥2,4,6-TMDBT≥4E,6-MDBT>1,4,6-TMDBT; if substituent in β site was identical, oxidative difficulty increased with the number of methyls in non-β site, oxidative difficulty of non-β site as meta-site was greater than that of non-β site as ortho-site; oxidative difficulty increased with the number of substituents and its carbons in β site.In adsorption desulfurization process, sulfur removal ratios of model and hydrotreated diesel with modified carbon adsorbent were83.4%and75.9%, respectively, presenting obvious physical characteristic; adsorptive selectivity for DBTs increased in the order of DBT <4-MDBT<4,6-DMDBT, obvious competitive adsorption among DBTs led to a lower total sulfur removal ratio by adsorptive desulfurization than that by oxidative desulfurization.