Adsorptive Desulfurization Of Gasoline Distillate Over Metal-Organic Frameworks

SOx formed after combustion of organic sulfur compounds in fossiol fuels will cause a lot of damage to the environment once they are emitted into the atmosphere, causing acid rain, also will poison the catalysts in automobile tail gas treatment devices. Therefore, countries all over the world have mandated stringent legislations to restrict sulfur content of fossiol fuels. Traditional HDS techniques can effectively eliminate organo-sulfur compounds in gasoline, but it will also cause a significant decrease of octane number in the product owing to the hydrogenation of olefins, thus causing inevitable decline in the quality of gasoline. At the same time, hydrogenation of olefin will increase unnecessary hydrogen consumption and equipment investment. The adsorption desulfurization technology which is simple, convenient, fast, with no decrease of octane number in gasoline product, will reduce the equipment investment and energy consumption and considered as a promising desulfurization technology.Metal-Organic Frameworks have been considered as a prospective candidate in adsorption desulfurization of gasoline, with superior specific surface area and tunable pore size and shape. We used HKUST-1, a three-dimensional Metal-Organic Frameworks in which Cu2+act as metal centers and H3BTC as organic ligands. Firstly, the optimum pre-treatment and operation conditions were explored in fixed bed desulfurization experiments with thiophene-cyclohexane as model fuels; secondly, the effects of Tolu and CHE added to model fuels were investigated; thirdly, the adsorption performances of organic sulfur compounds with different molecular sizes over HKUST-1were preliminary explored; lastly, HKUST-1was flushed with inert gas to inspect its regeneration behavior. The results show that HKUST-1pre-treated at220℃displayed the best breakthrough capacity, the optimal flow rate of the model gasoline was0.25mL/min, the best adsorption temperature is30℃. Under the above-mentioned optimal conditions, the adsorption capacity of thiophene was8.98mg S/g ad.; the adding of Tolu and CHE can cause decrease of breakthrough capacity of HKUST-1, however, the influence of CHE is smaller comparing to Tolu, which was ascribed to smaller dipole moment of CHE; the difference of adsorption capacities are ascribed to the synergism effects of different molecule sizes, sulfur electron densities and steric hindrance effects. Then the batch adsorption experiment of real FCC gasoline with large quantities of olefins and aromatics was carried on and the result showed a sulfur removal of40.7%; HKUST-1was completely regenerated under high temperature with N2flow. These results confirm that adsorption desulfurization of gasoline over HKUST-1have good application prospects.