Investigating polymeric entrainers for azeotropic distillation of the ethanol/water and MTBE/methanol systems

In this work, selected polymeric entrainers have been investigated to assess their capability of breaking the azeotrope of ethanol/water and MTBE/methanol systems. Solubility testing and group contribution model calculations were used to guide in the initial selection of potential polymers. Experimental VLE measurements were performed to determine whether the selected polymers are capable of breaking the azeotrope. We have found polymeric entrainers capable of breaking the azeotrope for the ethanol/water system. Poly(ethylene glycol) at 10 wt % and poly(acrylic acid) at 0.45 wt % did break the azeotrope for the ethanol/water system. This conclusion is based on composition and temperature data. Other polymers used with the ethanol/water system might be capable of breaking the azeotrope, but we could not conclusively determine this from the collected data. From the results obtained for the MTBE/methanol system, we were not able to definitively identify such entrainers. This is because of the difficulty in finding a polymer that will substantially dissolve in both MTBE and methanol and, at the same time, will provide the required specific interaction with each component. The experimental VLE data for selected systems were fit to the UNIQUAC model. A satisfactory fit was obtained, and the parameters are reported.