Separation of Alcohol-Water Mixtures by a Combination of Distillation, Hydrophilic and Organophilic Pervaporation Processes

Abstract

It can be stated that in the fine chemical industries, especially in the pharmaceutical industry, large amounts of liquid waste and industrial waste solvents are generated during the production technology. Addressing these is a key issue because their disposal often accounts for the largest proportion of the cost of the entire technology. There is need to develop regeneration processes that are financially beneficial to the plant and, if possible, reuse the liquid waste in the spirit of a circular economy, in a particular technology, or possibly elsewhere. The distillation technique proves to be a good solution in many cases, but in the case of mixtures with high water content and few volatile components, this process is often not cost-effective due to its high steam consumption, and in the case of azeotropic mixtures there are separation constraints. In the present work, the membrane process considered as an alternative; pervaporation is demonstrated through the treatment of low alcohol (methanol and ethanol) aqueous mixtures. Alcohol-containing process wastewaters were investigated in professional process simulator environment with user-added pervaporation modules. Eight different methods were built up in ChemCAD flowsheet simulator: organophilic pervaporation (OPV), hydrophilic pervaporation (HPV), hydrophilic pervaporation with recirculation (R-HPV), dynamic organophilic pervaporation (Dyn-OPV), dynamic hydronophilic pervaporation (Dyn-HPV), hybrid distillation-organophilic pervaporation (D + OPV), hybrid distillation-hydrophilic pervaporation (D + HPV), and finally hybrid distillation-hydrophilic pervaporation with recirculation (R-D + HPV). It can be stated the last solution in line was the most suitable in the terms of composition, however distillation of mixture with high water content has significant heat consumption. Furthermore, the pervaporation supplemented with dynamic tanks is not favourable due to the high recirculation rate in the case of tested mixtures and compositions.

Methane Oxidation to Methanol

“…The two theoretical studies described above reinforce the observations made by other authors of a beneficial effect of an aqueous environment on methanol formation. , Realistically, however, aqueous systems will produce a dilute methanol product, and new or emerging separations technologies will be needed to bridge the gap to an affordable, final distillation stage, most likely through pervaporation techniques. − Accordingly, work on direct methane oxidation in aqueous media should seek methanol product concentrations of at least a few wt %.…”

A Technoeconomic Model Coupled with HYSYS to Analyze the Electroreduction of Carbon Dioxide to Ethanol

“…[ 30 ] The azeotrope between water and ethanol limits ethanol purification using distillation at ≈96% (by mass). [ 31 ] Using a different technology, such as membrane separation, would be necessary to reach higher purification of ethanol needed for certain uses. However, this would increase the costs of separation.…”

Recent Advances in the Technologies and Catalytic Processes of Ethanol Production

“…Most energy-intensive units have remarkable effects on the gross energy demand that takes place during the distillation process. The cost of plant operation also increases due to the formation of an ethanol-water mixture that produces an azeotrope mixture where the simple distillation method cannot be used to change its composition [134,135].…”