Refining technology for polyester-grade coal to ethylene glycol based on melt crystallization and its benefit analysis

The coal-to-ethylene glycol process is attractive to cut down petroleum but suffers from high carbon emissions and energy consumption due to an azeotropic product mixture and complicated refining process. Herein, melt crystallization replacing conventional distillation unit was performed in consideration of the melting point difference between crude glycol components. The process studies of static layer crystallization and suspension crystallization were designed and evaluated. Over 99.90 wt% ethylene glycol was successfully prepared by suspension crystallization followed by mechanical centrifugation at optimizing conditions, therein, the crystal fragmentation induced by centrifugal force was the key factor for removing the trace impurities embedded in the crystal particle. The practical application potential analysis revealed our method could reduce 30.50%, 12.23% and 4.87% of energy consumption, minimum selling price and life cycle greenhouse gas emissions, respectively, compared with the conventional distillation pathway. These findings provided valuable insights into low-carbon and energy-saving coal-to-ethylene glycol technology.