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Ethylene oxide (EO) is an important raw material for producing ethylene carbonate (EC). However, the traditional method for the separation of EO from mixture gas by water in the refining process is high energy consumption. In this paper, two processes of manufacturing EC from EO mixture gas were studied by process simulation. Two processes for producing EC from EO mixture as raw materials without EO purification, called the OSAC process and the Modified OSAC process, were developed and assessed systematically. Both processes use EC as the absorbent to capture EO, avoiding the separation process of EO from solution. For comparisons, the EC producing process containing EO absorption by water, EO refinement and carbonylation process were also modeled, which was called the ERC process. Three schemes were designed for the EO absorber using EC as absorbent. Compared with the initial absorber scheme, the optimal liquid–vapor ratio is reduced from 1.66 to 1.45 (mass). Moreover, the mass distribution analysis for the three processes were carried out in the form of the material chain. It was found that, compared with the ERC process, the energy consumption of the OSAC and the Modified OSAC process is reduced by 56.89% and 30.03%, respectively. This work will provide helpful information for the industrialization of the OSAC process.

Utilization of CO2 to produce value-added chemicals is a promising approach to mitigate greenhouse gas emissions. In this work, a new process for the conversion of CO2 to dimethyl carbonate (DMC) and ethylene glycol (EG) was rigorously simulated and assessed in term of the technical performance and the environmental impact. The proposed model involves the conversion of CO2 catalyzed by ionic liquid-based catalysts, the reactive distillation with the reaction kinetics model, the pressure-swing distillation with rigorous phase equilibrium equations, and complex material-energy nexus between each unit. The results show that the carbon utilization efficiency of this process reaches 99% and the negative CO2 emission is 0.14 ton CO2/ton product achieving CO2 reduction. The green degree value of the entire process is 176.30 gd/h indicating that this new process can be evaluated as an environmental friendly process. Additionally, the retrofitted heat exchanger network designed via the pinch technique achieves 48.70% saving in heating utility consumption and increasing the green degree by 193.89 gd/h.