Enzymatic production of alcohol esters for recovery of diols produced by fermentation

Abstract

Diols produced in fermentation are processed in broth by esterification of the product diol with a carboxylic acid (e.g., fatty acid) and a catalyst (e.g., lipase) capable of esterifying the product diol, such as 1,3-propanediol, with the carboxylic acid to form the diol esters. The diol esters can be extracted from the broth, and the product diol recovered from the diol esters. The carboxylic acid can also serve as an extractant for removal of the diol esters from the fermentation medium.

Description

[0001]This application is a divisional of U.S. Ser. No. 13 / 326,660, filed Dec. 15, 2011, now pending, which is a continuation-in-part of U.S. Ser. No. 13 / 193,147, filed Jul. 28, 2011 which claims the benefit of U.S. Ser. No. 61 / 368,429, filed Jul. 28, 2010; U.S. Ser. No. 61 / 379,546 filed Sep. 2, 2010; U.S. Ser. No. 61 / 368,444, filed Jul. 28, 2010; U.S. Ser. No. 61 / 368,436, filed Jul. 28, 2010; U.S. Ser. No. 61 / 368,451, filed Jul. 28, 2010; and U.S. Ser. No. 13 / 163,243 filed Jun. 17, 2011 which claims priority to U.S. Ser. No. 61 / 356,290, filed Jun. 18, 2010, all expired and additionally claims the benefit of U.S. Ser. No. 13 / 161,168, filed Jun. 15, 2011, now pending which claims the benefit of U.S. Ser. No. 61 / 356,379, filed Jun. 18, 2010, now expired, and additionally claims the benefit of U.S. Ser. No. 61 / 440,034, filed Feb. 7, 2011; and U.S. Ser. No. 13 / 874,737 filed May 1, 2013 which claims the benefit of U.S. Ser. No. 13 / 163,243 filed Jun. 17, 2011; U.S. Ser. No. 61 / 356,290, fi...

AI Technical Summary

Benefits of technology

The invention provides a method for recovering a diol from a fermentation process by converting the diol into a diol ester. This simplifies the recovery and purification of the diol product. The carboxylic acid can be derived from biomass or added to the fermentation vessel. The catalyst can be added to the fermentation vessel or post-fermentation vessel. The method allows for the separation of the diol esters from the fermentation medium or post-fermentation vessel and recovery of the diol. The efficiency of the diol production can be increased by increasing the liquid-liquid mass transfer coefficient, extraction efficiency, or the rate of phase separation between the fermentation broth or post-fermentation vessel and the extractant. The diol can be 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, or 2,3-butanediol.

Problems solved by technology

Thus it is a challenge to recover the diols from large volumes of liquid by an economically viable process.

(2010) WO2010 / 141780) require large amounts of energy and thus are costly.

The extractant can become contaminated over time with each recycle, for example, by the build-up of lipids present in the biomass that is fed to the fermentation vessel as feedstock of hydrolyzable starch.

In addition, the presence of undissolved solids, from processed biomass feedstocks used for fermentation, during extractive fermentation can negatively affect the efficiency of the alcohol production.

For example, the presence of undissolved solids may lower the mass transfer coefficient inside the fermentation vessel, impede phase separation in the fermentation vessel, result in the accumulation of corn oil from the undissolved solids in the extractant leading to reduced extraction efficiency over time, increase the loss of solvent because it becomes trapped in solids and ultimately removed as Dried Distillers' Grains with Solubles (DDGS), slow the disengagement of extractant drops from the fermentation broth, and / or result in a lower fermentation vessel volume efficiency.

Wet milling is an expensive, multi-step process that separates a biomass (e.g., corn) into its key components (germ, pericarp fiber, starch, and gluten) in order to capture value from each co-product separately.

This process gives a purified starch stream; however, it is costly and includes the separation of the biomass into its non-starch components which is unnecessary for fermentative alcohol production.

However, fractionation does not remove the entirety of the fiber or germ, and does not result in total elimination of solids.

Furthermore, there is some loss of starch in fractionation.

Wet milling of corn is more expensive than dry fractionation, but dry fractionation is more expensive than dry grinding of unfractionated corn.

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