Study On Removal Of Sulfur Compounds From Petroleum Coke By Chemical Oxidation Process

The appearing and continuing of more and more high-sulfur coke is an inevitable trend in the development of petrochemical industry in China, and also one of the main factors that affect the quality of aluminium-consuming carbon anode. The study of high-sulfur coke desulfurization is much significant on improving the electrolytic production environment, reducing production costs, and the sustainable development of aluminium carbon. The author used chemical oxidation to remove sulfur from high-sulfur coke on the basic of previous work, chosen proper oxidation desulfurizer and optimized process conditions. The main results are as follows.(1) The experimental results of desulfurizer selection show that nitric acid-hydrochloric acid mixture system is the best desulfurizer in aqua, nitric acid, hydrochloric acid, acetic acid and hydrogen peroxide of single and mixed system. The orthogonal test was used to determine the degree of influence of various process conditions in desulfurization. The results show that the petroleum coke particle size is most sensitive to desulfurization efficiency, followed by the liquid-solid ratio, reaction time and mixed-acid ratio, and reaction temperature shows the lest sensitivity.(2) The influences of various process conditions on desulfurization ratio had been analyzed by single factor method during the desulfurization process of nitric acid-hydrochloric acid mixture system, and the technological conditions were optimized on the basis. The result shows that under the conditions of petroleum coke particle size<0.1mm, acid ratio of mixed acid 1.0±0.5, liquid-solid ratio 30mL/g, reaction time 24 h, and reaction temperature 60℃, the desulfurization ratio can achieve 63.50%.(3) The cycling desulfurization results of nitric acid-hydrochloric acid mixture system show that mixed acid can always keep the desulfurization rate more than 40% by adding 30% fresh mixed acid to recovery desulfurization liquid each time.(4) The morphology of petroleum coke changes little before and after desulfurization. The true density of petroleum coke decreased after desulfurization. The resistivity of calcined coke increased after desulfurization. The results of IR Testing show that most of the thiophene and mercaptan organic sulfur and all of inorganic sulfur can be removed from petroleum coke by mixed acid; the basic structure of petroleum coke does not change obviously after desulfurization.