Deep Desulfurization By Catalytic Oxidation In Emulsion System

It's difficult to finish the process of deep oxidative desulfurization by the hydrogen peroxide (H₂O₂) as oxidant because of water phase and oil phase can not mutual dissolution which resulted in higher mass transfer resistance. So in this paper, using the concept of emulsion- oxidation catalysis, combine emulsion catalysis with heterogeneous catalysis. The oxidation of sulfur-containing compounds (benzothiophene, BT) in model fuel (decahydronaphthalene) was conducted in emulsion oxidative system (water in oil, W/O) composed of model fuel, 30 wt% hydrogen peroxide, and a phase transfer catalyst under mild conditions.In this paper, the phase transfer catalyst in the catalytic oxidative desulfurization was researched, we made a high selectivity and activity catalyst by researching the type and concentration of the quaternary ammonium salt, metal modified and the temperature of the process of preparing catalyst. The experimental results indicated that the best conditions for catalyst preparation is methyl trioctyl ammonium chloride as quaternary ammonium salt, modified by adding ferric nitrate, the best temperature in catalyst preparation is 30℃.By the investigation on the conditions of desulfurization we determined the reaction conditions including speed of making emulsion, the weight ratio of catalyst and model fuel, the molar ratio between the oxidant and BT, the content of model fuel. The results indicated the best conditions to oxidative desulfurization is emulsification time 5min, standing time was 10 min, the weight between catalyst and model fuel 1%, and the molar ratio between oxidant and sulfur is 3:1. When the sulfur content is 1500μg/g, the desulfurization rate is 99.16% and the content of model fuel is 12.6μg/g.After a study on the extraction process to determine the best extraction conditions: volume ratio between extraction solvent and model oil is 0.5:1, including 40% water, the extraction time is 30min, the desulfurization rate of 99.65% and the content of model oil is 7μg / g.