| In this paper, a novel method for removing the carbon disulfide has been developed as a supplement of the technique for the crude benzene refining. It based on the reaction of carbon disulfide and sodium alcoholate to form the sodium xanthate. The xanthate can be easily removed during distillation due to the boiling point difference.In the chapter3, many basic experiments have been done. The sodium alcoholate in different forms was added to crude benzene, toluene and light benzene respectively. The content of carbon disulfide was direct determined using gas chromatograph with flame photometric detector (FPD) before and after treatment. The qualitative and quantitative analysis for carbon disulfide and xanthate were also carried out using Ultraviolet Spectrometer (UV). Based on above work, the mechanism of the chemical treatment process has been determined. Then the alcohol was chosen as the solvent to dissolve the sodium alcohol, and factors on the conversion processing have been studied.The results showed that:(1) Sodium alcoholate can be dissolve easily in the alcohol, not hardly in benzene.(2) The method for removing carbon disulfide base on the reaction of sodium alcoholate and carbon disulfide to generate xanthate in crude benzene is feasible and practical.(3) It has also worked well in removing carbon disulfide in toluene or light benzene. Compared two preparation methods relate to sodium alcoholate, the dissolving method and the synthesis method are mentioned. The former is much effective than the latter.(4) Dehydration is indispensably before the reaction of removing carbon disulfide. The reasons are as follows, sodium alcoholate can reacts with water to form alcohol and sodium hydroxide, and xanthate can also reacts with water to form carbon disulfide.(5) It is revealed that the sodium methylate is more easily react with carbon disulfide than the sodium ethylate during the carbon disulfide removal in toluene, light benzene and crude benzene.(6) The reaction between carbon disulfide and sodium alcoholate is the main reaction in the sphere of the reaction, the product of the reaction is sodium xanthate verified using UV.In the chapter4, the effects on CS2conversion rate were investigated by single factor analysis method, such as moisture mass, C2H5ONa/CS2molar ratio, the temperature and time of reaction. The optimum treatment conditions were get by using the orthogonal experimental design.The results showed that:(1) CS2conversion decreases with the increase of moisture mass percent. The conversion obviously decreases when the moisture mass is greater than0.1%. Under the room temperature, reaction time2hours, the CS2conversion can reach to85%. The influence of temperature on conversion is not so apparent. CS2conversion rate increases with the increase of molar ratio of reactant, but the speed-up is quite slow when the molar ratio is greater than10.(2) Through the analysis of orthogonal test, the result of intuitionistic analysis showed that the order of affecting CS2conversion rate was ranked as moisture mass percent> reaction temperature> reaction time> molar ratio of reactant. The best reaction conditions have been selected:the reaction temperature40℃, the molar ratio of reactant1.49, the moisture mass percent0.0445%, the reaction time120min.(3) Significance analysis of influential factors has been made extreme difference analysis and variance analysis, the results are consistent and the results both may be confirmed.(4)The optimum reaction conditions were obtained on basis of the experimental results, the moisture mass percent should less than0.1%, the reaction temperature is at20℃, the molar ratio of reactant is1.5, the reaction time should longer than120min.In the chapter5, the kinetics of the reaction between the carbon disulfide and the sodium ethylate had been studied. The apparent reaction order, frequency factor and activation energy were obtained. The relationship between the concentration of carbon disulfide and the ions from the sphere of the reaction were studied by analyzing main reaction and side reactions.The results showed that:(1)The reaction order is2.5752, CS21.2277and sodium ethylate1.3475.(2)The activation energy is69.94kJ/mol, and the pre-exponential factors is2027562156.(3) The concentration of CS2increases with the increase of hydrogen ion, and decreases with the increase of sodium ethylate. Hydrogen ion is produced by ionization of water. Consequently, the mass of water must be reduced and the concentration of sodium ethylate is greater than carbon disulfide.After the above basic experimental researches, the process for removing carbon disulfide has been established. In the chapter6, it was used to do a test on the crude benzene. |
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