Energy-saving reactive pressure-swing distillation process for separation of methanol - dimethyl carbonate azeotrope via reacting with propylene oxide

Pressure-swing distillation (PSD) is a widely used in the chemical industry to separate azeotropes without the introduction of a any third component; however, the process involves high energy consumption and operating costs are required owing to the change in pressure. For the separation of methanol–dimethyl carbonate azeotropes, an intensified reactive pressure-swing distillation (R-PSD) process has been proposed, wherein a reactive distillation column is used, instead of a high-pressure column, and the propylene oxide (PO) is introduced into the system as a reactant to reacts with methonal. To compare the feasibility of the proposed R-PSD process with the conventional heat-integrated PSD process, three indicators—total energy requirements, total annual cost, and CO2 emissions—were used. The results show that the R-PSD process performs better than the conventional heat-integrated PSD process in terms of energy, economics and environmental owing to the partial consumption of methanol and the simultaneous co-production of high-value propylene glycol methyl ether (PGME). Moreover, at 50% methanol consumption, the total energy consumption, total annual cost, and the CO2 emissions were reduced by 46.0%, 34.3%, and 45.0%, respectively, compared with the conventional heat-integrated PSD process. This implies the improved R-PSD process has significant energy-saving potential.