Energy integration and carbon flow analysis of process of CO2 chemical transformation to dimethyl carbonate and ethylene glycol
The chemical conversion of CO2 to obtain energy or chemicals with economic value can realize the resource recycling of CO2,which is one of the ideal ways to solve the problem of carbon neutralization in China.The production of dimethyl carbonate(DMC)and by-product ethylene glycol by two-step transesterification is an effective way to realize the chemical conversion and high-value utilization of CO2.In view of the technical problems of difficult CO2 activation and high production cost faced by the process,the process enhancement methods such as one-step absorption of ethylene oxide by ethylene carbonate,ionic liquid catalyst,reactive distillation to realize transesterification and extractive distillation to separate dimethyl carbonate and methanol were used.The whole process simulation was completed by Aspen plus followed by the transesterification parameter optimization using BP neural network and multi-objective genetic algorithm(NSGA-Ⅱ).And energy integration by pinch technology of transesterification process and carbon flow analysis of whole process were performed.The optimization results show that the consumption of thermal utilities in the transesterification process is reduced by 40.34％.The carbon flow analysis results show that the total carbon atom utilization rate in the system reaches 99.81％.Considering the indirect carbon emissions from energy consumption,the carbon atom utilization efficiency is 86.90％,and the net CO2 emission is 0.314kg CO2/kg DMC.Compared with the processes reported in the literature,the DMC product obtained in this process has a higher purity(99.9995％)and lower energy consumption(1.10kW·h/kg DMC),which can provide technical guidance for the chemical conversion of dimethyl carbonate and ethylene glycol from CO2.
chemical transformation of CO2transesterificationreactive distillationgenetic algorithmpinch technologycarbon flow analysis
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