Biofuels production from bio-derived carboxylic-acid esters

Abstract

A process for producing for producing biofuels compounds directly from carboxylic acid esters recovered from a fermentation system is described. The process involves taking a fermentation broth that has been reduced to a dry powder containing free organic acids; reacting the carboxylic acid in the powder with an alcohol solvent under a CO2-containing atmosphere in substantial absence of any other acid catalyst at a reaction temperature and pressure that corresponds to supercritical, critical or near critical conditions for at least one of the alcohol or CO2 to synthesize an ester, then subjecting the ester to either hydrogenolysis or hydrogenation to form a biofuel.

Description

PRIORITY CLAIM[0001]The present Application claims benefit of priority from U.S. Provisional Application No. 61 / 739,790, filed Dec. 20, 2012, the contents of which are herein incorporated.FIELD OF INVENTION[0002]The present invention relates to a process for the production of certain biofuels. In particular, the invention pertains to a method for producing biofuel products from bio-derived esters of carboxylic acids by means of either hydrogenation or hydrogenolysis.BACKGROUND[0003]Development of alternative fuels has gained increasing importance with increased awareness of environmental concerns and in the wake of economic pressures and fuel costs that have resulted from supply volatility of petroleum and other fossil-based resources. Policy makers have recognized this importance and have encouraged production and increased use of biofuels. As interest has grown in moving away from petrochemical or natural gas-derived hydrocarbon sources, some have concentrated on finding renewable...

AI Technical Summary

Benefits of technology

The present methods provide additional features and benefits that improve upon existing technologies. These features are useful and useful for understanding the invention. The details of the methods, including benefits, are described in the following summary and examples. Overall, the invention provides better technology with more benefits and improvements.

Problems solved by technology

Although the fermentative production of carboxylic acids, such as malic or succinic acid, has several advantages over petrochemical-based fuels, the production costs for the bio-based carboxylic acids have been too high for bio-based production to be cost-competitive with petrochemical production regimes.

Generation of carboxylic acid salts versus the free organic acid form brings about significant processing costs.

About 60% of the total production costs are generated by downstream processing, because of the difficulties associated with the separation and purification of the acids and their salts in the fermentation broth.

Recovery of carboxylic acids as salts has a number of associated problems and requires several different steps in post-fermentation, downstream processing to isolate free acids and to prepare the carboxylic acids for chemical transformation and to convert the raw acids to useful compounds.

The amount of reagent used can increase costs.

For instance, calcium salts of C4 diacids have a very low solubility in aqueous broth solutions (typically less than 3 g / liter at room temperature), and arc not suitable for many applications for which a free acid species is needed, such as chemical conversion to derivative products like butanediol and biofuels.

All of these individual operational units contribute to the overall costs of the process.

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