Submitted to: Chemical Engineering Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 5, 2006
Publication Date: May 12, 2006
Citation: Stephenson, S.K., Offeman, R.D., Robertson, G.H., Orts, W.J. 2006. Ethanol and water capacities of alcohols: a molecular dynamics study. Chemical Engineering Science. 61: 5834-5840. Interpretive Summary: Significantly more usable energy may be produced from the same amount of natural resources by improving energy efficiency in the processing steps that convert and purify ethanol for use as a fuel. As part of research to develop liquid-liquid solvent extraction for ethanol separation and purification, this research outlines computer methods to predict the efficiency of a given solvent for these applications. Results from molecular dynamics simulations on 24 linear alcohol isomers containing from 6 to 12 carbon atoms show the effects of hydroxyl location on bulk hydrogen-bonded structures which correlate well with the solvents performance. These findings will improve the ability to rapidly optimize liquid-liquid extractions by focusing the selection process on a few candidate solvents, reduce the need for time consuming experiments, shorten the development time for the process and facilitate successful implementation of the method.
Technical Abstract: The extended hydrogen bond networks formed by alcohols are good indicators of their capacities to hold water. Results from molecular dynamics simulations on 24 linear alcohol isomers containing from 6 to 12 carbon atoms show the effects of the hydroxyl location on bulk hydrogen-bonded structures. Calculated oxygen-oxygen radial distributions obtained from simulations were correlated to experimental liquid-liquid solvent extraction studies involving ternary water/ethanol/alcohol systems. It was found that the hydroxyl group location determines the primary structure of the hydrogen bond network occurring within an alcohol and that an alcohol's capacity for water correlates directly to the size of this network.