Study On The Advanced Desulfurization Technology For High-sulfur Petroleum

Recently, as the high-sulfur crude oil was refined, the yield of high-sulfur petroleum coke is increasing year by year. High-sulfur petroleum coke can corrode equipments and pollute environment in the produce process. When it is used as the raw materials of prebacked anode, the high content sulfur will seriously influence the quality of prebacked anode. So it is very important for sustainable development of aluminium electrolysis and carbon field, the decrease of environment pollution and other useful prospect of high-sulfur to develop the advanced technology for removing the sulfur from petroleum coke.In this paper, the high-sulfur petroleum was desulfurized by the way of chemical oxidation and high-temperature calcinations. In the normal temperature and pressure, the mixed solution of acid A and hydrogen peroxide was selected as the best system of chemical oxidation desulfurization comparing to the results of chemical oxidation desulfurization of four desulfurizers. The single factor method was used to inspect the influence of the petroleum coke particle size, the liquid-solid ratio, and reaction time on the desulphurization rate of acid A and hydrogen peroxide. The best conditions for desulfurization is as follows:petroleum coke particle size of0.15mm, the liquid-solid ratio of20mL/g, the response time of24h, and desulfurization rate of20.72%. In this paper, we still discussed the reinforcement effect of ultrasonic radiation to chemical oxidation in the process of desulfurization. The result indicates, under the condition of ultrasonic of six hours, the desulfurization rate of four kinds of oxidants are higher compared to the desulfurization rate under condition of non-ultrasonic oxidation of24hours. In addition, the desulphurization rate of acid A and hydrogen peroxide mixed solution is26.46%,which is the highest among the four oxidations. However, the effect of ultrasonic radiation on the system of glacial acetic acid is most obvious, and the desulfurization rate is300%compared to the desulfurization rate conventional oxidation. Electrochemical desulfurization of different petroleum coke was carried out with electrolyte of sodium hydroxide. The results of the study show that, the desulfurization rate of diffrent petroleum cokes is not the same under the same condition of electrolysis. Specifically, the desulphurization rate of the petroleum coke with low-sulfur content is higher with a value of26.10%, but the desulphurization rate of the low-sulfur petroleum coke is relatively low and with value less than6%. And the bigger the particle size of petroleum has the lower the the desulphurization rate.Desulfuration of petroleum coke is implemented by the way of calcination with high tempreture from1000℃to1600℃. The research shows that desulfurization rate increases with the increase of the temperature. The variation of desulfurization rate is not obvious in range of1000℃and1400℃, and when the tempreture is1400℃, the desulfurization rate is32.14%, when the tempreture is over1500℃, the desulfurization rate begin to increase quickly, when the tempreture is1600℃, the desulfurization effect is obvious with a desulfurization rate of86.51%. In the temperature of1300℃, with the decrease of the petroleum coke particle size, the desulfurization rate increases. Besides, the influence of the particle size of raw materials on the desulphurization rate is not relatively obvious compared to the effect of temperature on the desulphurization rate. Desulphurization of petroleum coke is proceeded by the combine way of chemical oxidation and high temperature calcination. The research indicates that the desulfurization rate of petroleum coke is55.12%, which is treated by chemical oxidation with the mixed solution of acid A and hydrogen peroxide and high temperature firing (1300℃). The value of desulphurization rate is significantly higher than that of directly calcination or oxidation.The effect of desulfurization of calcined petroleum coke is not obvious and poor compared to that of green coke, when the methods of chemical oxidation, electrochemical desulfurization, and chemical method combining with the high temperature firing are used.The petroleum coke before and after the desulfurization was analyzed by Scan Electron Microscope(SEM), X-ray Diffraction(XRD) and FT-IR. The analysis indicates that the basic structure of petroleum coke treated by the mixed solution of acid A and hydrogen peroxide is not evidently changed, and the graphite crystal structure also won’t be destroyed after calcination. But the microscopic surface outline of petroleum coke treated by the mixed solution of acid A and hydrogen peroxide becomes clear and fruity, and the organic molecules in particle surface reduce. Moreover, the surface of treated petroleum coke present long and narrow imperceptible crack, which helps the internal sulfur remove in the process of calcination. The surface of petroleum treated by chemical oxidation and calcination of1300℃exhibit more and bigger cracks, which is in favour of adhesion of calcined petroleum coke and coal tar.