Process for producing 1, 3-propanediol

1. A process for the recovery of 1,3-propanediol from a fermentation broth comprising 1,3-propanediol, comprising the steps of:

contacting a fermentation broth that comprises water, 1,3-propanediol, and at least one contaminant selected from glycerol, glucose, and butanetriol, with at least one solvent extractant to form a first mixture, and

separating the first mixture into a first phase and a second phase,

wherein the first phase comprises a majority of the solvent extractant and at least some of the 1,3-propanediol that was present in the fermentation broth, and the weight ratio in the first phase of 1,3-propanediol to at least one of glycerol, glucose, or butanetriol, is greater than the weight ratio of 1,3-propanediol to the same contaminant in the fermentation broth prior to the fermentation broth being contacted with the solvent extractant,

wherein the second phase comprises a majority of the water and at least some of the contaminant from the fermentation broth,

recovering 1,3-propanediol by removing the first phase from the second phase, wherein the removed first phase further comprises at least some water,

contacting the removed first phase with at least one hydrophobic solvent to form a second mixture,

separating the second mixture into a third phase and a fourth phase,

wherein the third phase comprises the majority of both the solvent extractant and the hydrophobic solvent of the second mixture,

wherein the fourth phase comprises 1,3-propanediol and the majority of the water of the first phase, and

wherein the weight ratio in the fourth phase of 1,3-propanediol to any one contaminant present is greater than the weight ratio of 1,3-propanediol to the same contaminant in the fermentation broth prior to the fermentation broth being contacted with the solvent extractant.

2. The process of claim 1 , wherein the weight ratio of the removed first phase to the hydrophobic solvent is between about 4:1 and 1:4.

3. The process of claim 1 , wherein the hydrophobic solvent is selected from solvents with log P in the range of between about 3.5 and 10.

4. The process of claim 3 , wherein the solvent is an alkane having from 6 to 12 carbon atoms.

5. The process of claim 1 , wherein the at least one solvent extractant is selected from the group consisting of alkanols, ketones, esters, acids, ethers or vegetable oils.

6. The process of claim 5 , wherein the solvent extractant is selected from the group consisting of pentanol, propan-1-ol, hexanol, oleyl alcohol, 4-methyl pentan-2-one, isopropyl acetate, tributyl phosphate, oleic acid, soya oil, and castor oil.

7. The process of claim 6 , wherein the solvent extractant is selected from the group consisting of hexanol and tributyl phosphate.