A promising alternative potential solution for sustainable and economical development of coal to ethylene glycol industry: Dimethyl oxalate to methyl glycolate process

The rapid expansion of coal-to-ethylene glycol (CtEG) industry leads to an oversupply of ethylene glycol and poor economic performance. Dimethyl oxalate is an important intermediate in this process, which can be selectively hydrogenated to methyl glycolate by changing the catalyst. Methyl glycolate is urgently needed for large-scale production of high-end degradable polyglycolic acid. However, the reported literature neither explores whether this alternative technology can turn the CtEG process into profit nor investigates the effect of various catalysts on the system performance of this alternative technology route. Therefore, three coal-to-methyl glycolate (CtMG) processes with various catalysts are proposed and optimized through rigorous modeling and simulation. The advantages and disadvantages of these three CtMG processes are analyzed and compared with the CtEG process. Results show that the dimethyl oxalate to methyl glycolate process with Ag-based catalyst has the highest yield of methyl glycolate (93.51%) compared with other catalysts. Three proposed CtMG processes have better techno-economic performance than the CtEG process. The carbon utilization and exergy efficiencies of the proposed CtMG processes are increased by 11.47%–19.22% and 9.58%–19.01%, respectively. The proposed CtMG processes turn a loss into a profit, which can improve the internal rate of return of CtEG process from −0.31% to higher than 24.14%. In particular, the CtMG process with Ag-based catalyst has the highest exergy efficiency, 50.95%, and internal rate of return, 27.48%. Therefore, CtMG technology can significantly relieve the survival pressure of CtEG enterprises, and improve their profitability and anti-risk capabilities. The research results of this study can provide an excellent theoretical basis and technical support for the transformation and upgrading of the CtEG industry.