Study On Catalytic Oxidative Extraction Desulfurization Of Diesel With Supported Heteropoly Acid

Most countries have regulated to produce and use eco-friendly ultralow sulfur diesel fuel with the increasingly environmental awareness.The conventional HDS process is carried out under severe conditions, which result in high operating cost, and is less effective to produce ultralow sulfur compounds fuel. Therefore, much attention has been paid to the oxidative desulfurization due to its mild reaction condition, high efficiency and environmental protection.The phosphotungstic acid used in oxidative desulfurization reaction has small specific surface area, and was hard to separate in homogeneous reaction, so the self-made supported phosphotungstic acid was prepared in this paper, the oxidative desulfurization results was better, and the recycled catalysts could decrease the industrial costs.The catalyst of phosphotungstic acid( HPW) loading on Zr O2 was prepared by impregnation method, and characterized by XRD, FT-IR. Wth HPW/Zr O2 as catalyst,30% hydrogen peroxide as oxidant and cetyltrimethylammonium bromide( CTAB) as surfactant,organic sulfur compounds were removed from model oil by catalytic oxidation method. The effects of reaction temperature, reaction time, the amount of catalyst, the amount of CTAB and the amount of H2O2 on desulfurization were investigated. Desulfurization performance of different fuel oil, transfer agents and catalysts were studied.The effects of extraction agents, extration temperature, extraction time, solvent/oil ratio and extraction series for FCC diesel were also inspected. At last,the catalysts were recycled and evaluated, and the extract phase were utilizated comprehensively.The results showed that Zr O2 was a good carrier and the HPW keggin structure remained unchanged, which played the catalytic role.Under the optimal conditions of model oil: reaction temperature 60 ℃, reaction time 70 min, mole ratio of H2O2 to sulfur 3.0, CTAB dosage 0.2 wt %( based on the mass of diesel,the same below),HPW/Zr O2 dosage 2.0%, the sulfur content in the diesel could be lowered from 3000 ppm to 96 ppm, with the sulfur removal rate of 96.8%. The results showed that different fuel oil has different catalytic performance with the same catalytic,for one specific oil,CTAB is the best transfer agent, HPW is the best heteropolyacid and Zr O2 is the best carrier, the sulfur content of diesel fuel could be lowered from 3452 ppm to 102 ppm,with the sulfur removal rate of 97.0 % in the best oxidation conditions.FCC diesel was oxidative in the best conditions, then extracted with solvents. The best extraction conditions of FCC diesel were as followed: furfural as the optimal extraction solvent,extraction temperature 35 ℃, extraction time 10 min, furfural/FCC diesel 1/2 g/g,extraction series 4, the sulfur content of diesel fuel could be lowered to 47 ppm, with the sulfur removal rate of 98.6 %, which meets the standard of GB19147-2013. The desulfurization rate reach above 88.0 % after the catalysts were recycled three times.And the used extractants could be recycled by distillation, so that increased the economic benefits of refinery plant.