Azeotrope separation of ethyl propionate and ethanol by extractive distillation and pressure swing distillation method

Abstract

Ethyl Propionate is produced by esterficating propanoic acid and ethanol in the presence of a catalyst (sulphuric acid). However, in ethyl propionate production, ethanol and ethyl propionate forms azeotrope, resulting in its poor purity. In this regard, Aspen Plus simulation software has been used to analyze the separation by performing property analysis and phase behavior of each component and then simulated azeotrope separation by using two methods: extractive distillation method-(EDM) and pressure swing distillation method-(PSDM). For extractive distillation method-(EDM) two novel heavy entrainers (glycerol and ethylene glycol) have been used. Property analysis for both materials was favorable, however, glycerol showed more promising results than ethylene glycol. In EDM-simulation process, the separation capability of glycerol was higher than ethylene glycol for ethyl propionate with the purities of 99.90 and 99.71 mol% respectively, which were extracted from 1st radfrac extractive distillation column-(RF-EDC-1). Whereas, the resultant purities for ethanol/glycerol and ethanol/ethylene glycol in 2nd radfrac extractive distillation column-(RF-EDC-2) were 99.83/99.99 and 99.47/99.99 mol%, respectively. However, reboilers total heat duty in (RF-EDC-1 + RF-EDC-2) for glycerol and ethylene glycol were 6818.38 kW and 5351.66 kW respectively. In PSDM, the property analysis was performed by the variation of pressure and were favorable for this process. The resultant purities of ethyl propionate and ethanol in their respective 1st radfrac distillation column-(RF-DC-1) and 2nd radfrac distillation column-(RF-DC-2) were 99.99 % and 99.00 % respectively. The reboilers total heat duty (RF-DC-1 + RF-DC-2) was 3839.638 kW. The economic analysis in terms of total annual cost (TAC) for EDM (glycerol and ethylene glycol) and PSDM was done, where, EDM(glycerol) was 27.01 and 33.47 percent more efficient among other two methods.