Desulfurization Of Gasoline And Diesel Oil By Adsorption And Oxidation

Desulfurization of fuel oil has long been a hot spot of the scientists all over the world since the fuel refining industry started. Conventional hydrodesulfurization techniques are constantly being improved, but there are some thiophene derivatives which are difficult to be removed via the hydrogenation process, therefore, it's necessary to find new desulfurization methods to solve the problem.At present, the adsorption desulfurization technology has attracted a widespread attention as a non-hydrodesulfurization process because of its simple equipment and low operating costs. At the same time, oxidation desulfurization process tends to be a future desulfurization technology because it can convert some of thiophene sulfides into corresponding sulfones or sulfoxide sulfides at mild conditions.In this paper, three kinds of modified activated carbons NAC, SAC and AAC were obtained by treating the powder activated carbon (AC) with concentrated nitric acid, oil of vitriol and aqua fortis respectively. The corresponding isothermal adsorption data of NAC, SAC, AAC and AC were measured in benzothiophene (BT)-Octane, dibenzothiophene (DBT)-Octane and 3-methyl-thiophene (3-MT)-Octane systems at 30℃and 50℃. The experimental data were treated by Freundlich and Langmuir isothermal adsorption equations. The results showed that all data were well correlated with Langmuir isothermal adsorption equations. It was also noted that the adsorption capacities sharply improved after the modifications, and the adsorption capacities followed the order AAC＞NAC＞SAC＞AC. Compared to AC, the maximal adsorption amounts of AAC at 30℃for BT, DBT and 3-MT increased 88.7%,63.4% and 95.1% respectively. The FTIR and Boehm titration results showed that the more oxygen-containing functional groups of activated carbon had, the stronger adsorption capacity of activated carbon was. After regeneration for four times of AAC, the equilibrium adsorption amounts of BT, DBT and 3-MT were still kept at 71.5%,72.7% and 40.7% of the first time respectively, which suggested a good regeneration.In the catalyzed oxidation-extraction experiment, [(C4H6N2)2H]3 [P(W3O10)4] showed a good catalytic action, ionic liquid [BMIM]BF4 has a stronger desulfurization ability than [BMIM]DMP. By treating the model gasoline with catalyst [(C4H6N2)2H]3[P(W3O10)4], extractant [BMIM]BF4 and hydrogen peroxide at 60℃, the desulfurization ratio of 97.3% and 98.9% were obtained for BT and DBT, and the desulfurization ratio was kept at 78.2% and 83.7% after three times reuse of [BMIM]BF4 for the same BT-Hexane and DBT-Hexane systems.