The Process Research Of Oxidation-Adsorption Removal Of Thiophene Sulfide From Fuels And Preparation Of Catalysts On Desulfurization

Faced with an increasingly serious environmental problems, the world has developed increasingly stringent fuel sulfur standards. In order to meet the new fuel standards, fuel desulfurization technology is becoming more and more attention. The traditional hydrodesulfurization(HDS) needs high operating pressure, temperature, costs and it is very difficult to removal of dibenzothiophene(DBT) and its derivatives. Oxidation and adsorption desulfurization process have many advantages that process is simple, low cost, easy to remove dibenzothiophene and its derivatives, and they become the most promising desulfurization technology.In this paper, activated carbon as a carrier and a series of desulfurizer were prepared by impregnation method and the desulfurization performance was evaluated. The types of modifier, type and load of the metal, adsorption time, calcination temperature on the influence of desulfurization rate were investigation in the model oil and the catalysts were characterized by gas chromatography, scanning electron microscopy, infrared spectroscopy and so on.Firstly, activated carbon was pretreated with deionized water, HCl and oxidants in order to remove the ash and change the number and species of oxygen-containing functional groups, the activated carbon has been characterized before and after modification, and the desulfurization performance was evaluated. The results suggested that:after pretreatment, the impurities are removed and the specific surface area and pore volume increase; the desulfurization rate enhancement after nitric acid treatment, because the acidic group increases on the surface of the activated carbon and the possible mechanism was discussed.The phosphotungstic acid (PTA) supported on activated carbon modified HNO3 and PTA/AC catalyst was prepared and desulfurization experiment was carried out. The study found that under the conditions:the mass fraction of phosphotungstic acid was 10%, calcination temperature was 400℃, the desulfurization rate of PTA/AC catalyst was highest. In BT/hexadecane model oil-hydrogen peroxide system, the oxidation kinetics of the BT was the first order reaction and the apparent activation energy was 31.7kJ/mol.Activated carbon modified by nitric acid as carrier, copper nitrate and nitrite cerium as active components, the adsorbent was prepared and the desulfurization experiments were carried out and adsorbents were characterized. The results suggested that:the active center of adsorbent was mainly Cu2O and CeO2, under the optimum conditions, the desulfurization rate reached 96.6% and 95.9% respectively.When both Cu and Ce on the adsorbent, the desulfurization performance was investigated. The study found that when the model oil system only contain thiophene and n-octane, Cu2O and CeO2 molar ratio was 2:1, the desulfurization rate reached 96.7%; when toluene was added, Cu2O and CeO2 molar ratio was 1:2, the desulfurization performance was best. The effect of different regeneration methods of the adsorbent and frequency of adsorbent use times on desulfurization performance were investigated. The study found that toluene and acetonitrile had the best effect, but nitrogen gas high temperature regeneration was poor. The acetonitrile as the solvent, the adsorbent repeated use 4 times, the desulfurization rate only a small decline, suggesting that the adsorbent had good stability.