Heat integrated technology assisted pressure-swing distillation for the mixture of ethylene glycol and 1,2-butanediol

Production of ethylene glycol (EG) from coal derived syngas has been an alternative to the petroleum route, where a certain amount of mixture product of EG and 1,2-butanediol (BDO) is inevitably side-produced as a low value-added product. Thus, designing a separation process with high economic performance for this azeotropic mixture is highly desirable. Herein, pressure-swing distillation (PSD) processes without and with aid of heat integration are designed and simulated by using Aspen Plus for recovering high purity EG and BDO from the mixture product. The results show that the CO2 emissions and total annual cost (TAC) of the four modified PSD process have been significantly reduced compared with the optimized basic PSD process. Among these processes, the full heat integrated pressure-swing distillation process has the best economic performance with TAC decreasing by 35%, while the bottom flash pressure-swing distillation process has the best environmental performance with CO2 emissions decreasing by 95%. These findings provide fundamentals for the rational design of industrial separation and purification of EG and BDO azeotrope in the coal-based EG production.