Revisiting the extraction and dehydration of ethanol by the hot propane process

Abstract

Conventional liquid extraction is not a suitable separation method for the recovery and dehydration of ethanol and other light alcohols from aqueous solutions. Condensed non-polar gases like propane and CO2 looked promising as potential solvents. The favorable effect of temperature on the alcohol distribution coefficient of condensed propane led to the development of the hot propane process (HPP) for extraction and dehydration of alcohols. The dehydration of the alcohols took place in the solvent recovery column, thanks to the water entrainment effect of propane. Earlier pilot plant studies confirmed the process feasibility. In the present work, we design mixtures of propane + CO2 and phase conditions that fulfill the key properties of the HPP: (1) good alcohol distribution coefficient in the high-pressure extractor and (2) adequate water entrainment effect in the solvent recovery column.