A scheme for producing gasohol by distillation and then extraction of the resulting 90 wt % ethanol, 10 wt % water feed with gasoline is presented. Theoretical calculations for extraction with pure solvents are presented and used as a guide for gasoline extraction. Experimental results from a Scheibel column are presented for extraction with heptane, heptane-toluene blends, a commercial gasoline, and a naphtha. These results agreed qualitatively with the theoretical predictions and showed that a 10% ethanol gasohol mixture can be produced by extraction with gasoline.Although it is now a commercial process, the use of fermentation alcohol as a liquid fuel in gasohol is still controversial. The controversy centers around the net energy balance for alcohol production and the overall economics. These questions have been considered in detail by Chambers et al. (1979), Scheller and Mohr (1977), and Scheller (1978. The most energy intensive step in the process is the separation of ethanol from water. This step has recently received considerable attention. Black (1980) modeled improved distillation schemes, Ladisch and Dyck (1979) and Fanta et al. (1980) studied adsorbent drying, Wymore (1962) reported use of cation exchange resins, Gregor and Jeffries (1979) studied membrane methods, and Hartline (1979) reviewed a variety of possible separation methods.In the older literature extraction of ethanol from water was studied by several researchers. Othmer and Trueger (1941) and Othmer and Ratcliff (1943) used n-amyl alcohol and isoamyl alcohol to extract dilute alcohol from water. Schiebel (1950) investigated mixed solvent systems of methyl-n-amyl ketone and glycol, and o-xylene and glycol. Doronin et al. (1963) also studied ethanol extraction. Roddy (1981) investigated the distribution of ethanolwater mixtures in a variety of organic solvents. Recently, the possibility of direct extraction of ethanol with gasoline has invoked a flurry of letters to the editor of Chemical and Engineering News (Meyers, 1980;Arora, 1980; Gelbein, 1980, and Othmer, 1980). Some of these writers were quite critical of the idea. In this paper we present a proposed scheme for separation of ethanol from water by extraction with gasoline, and present experimental data on the extraction step. Separation MethodThe method proposed for recovery of the ethanol is shown in Figure 1. The predistillation column concentrates the ethanol from a feed concentration of 6 to 12 wt % to approximately 90 wt %. This mixture is then directly extracted with gasoline to form gasohol as a product. The raffinate from the extraction column is sent to a gasoline recovery still and the bottoms from this still is recycled to the predistillation column. It may be possible to send the raffinate directly to the predistillation column and recover the gasoline in this column along with the ethanol. The direct use of gasoline in a fermentation plant is not new since gasoline is used commercially as the entrainer in azeotropic distillations (Hartline, 1979).'EG&G Idaho, Inc., Idaho ...

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