Process Study Of Ammonification And Acid Precipitation Reaction In The Production Of Sodium Saccharin

As an important organic synthesis intermediate in chemical industry,sodium saccharin is widely used in food additive industry,feed additive industry and electroplating industry.With the development of the economy and various industries,the demand and quality of saccharin is getting higher and higher.The traditional ammoniation process uses toluene as solvent,which has operational risks and serious pollution in the production process,so it is very important to improve and optimize the present process.In this paper,the ammonification reaction in saccharin production process was firstly modified by using water instead of toluene solvent for the ammonification experiment.By investigating different dosing methods,it was found that the reaction method of mixing water with 2-Methoxycarbonylbenzenesulfonyl chloride before adding ammonia has unique advantages,in which the reaction conditions are milder and the environmental pollution is effectively reduced;Based on the single-factor experiment,the ammonification reaction was optimized by combining response surface analysis,and the interaction between the factors was analyzed with the yield of saccharin as the evaluation criterion.The best process parameters were finally obtained as follows:n(2-Methoxycarbonylbenzenesulfonyl chloride): n(ammonia)= 1:4.22,the reaction temperature was 74℃,the reaction time was 32 min,and the yield of saccharin was88.75%.The kinetics of the ammonification reaction was investigated under optimal process condition,and the relevant kinetic equations were calculated by fitting the concentration-time variation curves of 2-Methoxycarbonylbenzenesulfonyl chloride,and the relevant reaction processes of the ammonification reaction were analyzed.In the experiment of activated carbon decolorization reaction,by investigating the effects of different types of activated carbon on the yield and chromaticity of saccharin,the experiment was conducted on the solution of ammonium saccharin,the results demonstrated that the decolorization effect of coal-based activated carbon was the best,but the effect of different types of activated carbon on the chromaticity of saccharin was extremely insignificant;the results of the single-factor experiment showed that the amount of activated carbon,p H value and reaction temperature had a significant effect on the yield of saccharin.The response surface methodology was used to optimize the parameters of the decolorization reaction,and it was found that there was a weak interaction between p H and activated carbon dosage,and the final optimal reaction conditions were obtained as follows: 4% activated carbon dosage,p H 3.6,reaction temperature 44°C,and the yield of saccharin was 87.25%.The purity of saccharin was improved by 1～2% compared with that under the condition of no activated carbon adsorption.The single-factor experimental optimization was carried out for the acid precipitation reaction,and it was found that the magnitude of endpoint p H,reaction time,reaction temperature and hydrochloric acid concentration had significant effects on the saccharin yield,and the reasons for each factor affecting the saccharin yield were analyzed and summarized.Based on the single-factor optimization,the acid precipitation reaction was investigated by response surface optimization method,and a four-factor and three-level experimental model was established,and the reliability and accuracy of the model were proved by significance test and ANOVA.The experimental model demonstrated that the influence of each factor on the saccharin yield was in the following order: p H>reaction time>reaction temperature>hydrochloric acid concentration,and the interaction between p H and reaction temperature,p H and reaction time,and reaction time and reaction temperature was obtained by analyzing the experimental data;the optimized process parameters after response surface optimization:p H was 0.80,reaction temperature was 24℃,reaction time was 13 min,hydrochloric acid concentration was 30%,and the saccharin yield under this condition could reach89.25%;Finally,the products of the acid precipitation reaction were characterized and the reaction processes related to the acid precipitation reaction were analyzed and summarized.After the optimization of the saccharin production process,the yield of saccharin products was improved and the production process conditions were safer and more environmentally friendly.