Submitted to: Industrial and Engineering Chemistry Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 23, 2005
Publication Date: July 17, 2005
Citation: Offeman, R.D., Stephenson, S.K., Robertson, G.H., Orts, W.J. 2005. Solvent extraction of ethanol from aqueous solutions. 2. Linear, branched and ring-containing alcohol solvents. Industrial and Engineering Chemistry Research. 44: 6797-6803. Interpretive Summary: Currently the energy required to distill a gallon of ethanol from a fermentor and dehydrate it is equivalent to 18-22% of the fuel value of a gallon of ethanol. Solvent extraction is a less energy-intensive alternative to distillation. This paper is the second in a series that searches for better solvents for recovering ethanol from aqueous solutions, and seeks to develop a better understanding of solvent molecular properties that enhance extraction. This paper examines the effects of systematic molecular structure changes on the extractive performance of 57 alcohol solvents. Improvements in extraction solvents could lead to reduction in energy required to produce ethanol from grain and biomass sources.
Technical Abstract: Distribution coefficients have been measured for the partitioning of ethanol and water from aqueous mixtures into 57 different alcohol solvents. The study has focused on the effects of systematic variations in chemical structure of the alcohols. Factors found to be important include chain length and hydroxyl position for the x-alcohols (i.e., 1-heptanol through 1-dodecanol, 2-heptanol through 2-undecanol, etc.), branch structure (e.g. methyl, ethyl, n-propyl, i-propyl, etc.) for a branch located on the hydroxyl carbon, location of the branch relative to the hydroxyl carbon, and multiple branching.