The substitution of fossil resources by renewable alternatives is a major challenge for carbon-neutral society. It is important for carbon neutrality that various carbon compounds, as well as electricity currently used, can be produced from renewable raw materials. For the carbon compounds such as base chemicals, specialty chemicals, or fuels, various carboxylic acids from anaerobic fermentation can be converted by Kolbe electrolysis. Volatile fatty acids(VFAs) that are secreted extracellularly can be classified into short-chain carboxylic acids (SCCAs), such as acetic acid, propionic acid, butyric acid, and medium-chain carboxylic acids (MCCAs) with chains of 5~8 carbons (valeric acid, caproic acid, heptanoic acid, and caprylic acid). During anaerobic fermentation, SCCAs are elongated to MCCAs by the addition of 2-carbon (C<sub>2</sub>) units. Several bacteria have been reported to produce MCCAs by the reverse β-oxidation pathway (r-BOP). We have reported the various MCCAs production including odd-chain carboxylic acid (OCCA), even-chain carboxylic acids (ECCAs), and branched MCCAs from diverse carbon sources such as food wastes, Jerusalem artichoke tubers, glucose, fructose, galactitol, sucrose, etc. From these diverse chemical structures of MCCAs, alkanes, alcohols, and esters with chains of 6~14 carbons can be produced via Kolbe electrolysis. Throughout the Kolbe electrolysis, microbial chemical production and renewable electrical energy production can be integrated to create the need for suitable storage and conversion technologies of the wind power or photovoltaics having temporal fluctuations. MCCAs are produced cheaply by anaerobic conversion of renewable wastes and subsequently electrochemically upgraded to yield energy-dense alkanes, alcohols, and esters. Since the electrochemical MCCAs conversion is much faster than the MCCAs production, intermittent electrolysis during periods of excess renewable electrical power is possible. The integrated process of anaerobic MCCAs production and Kolbe electrolysis is promising to produce drop-in fuels and chemicals without any further downstream processing.

Syncretic n-alkane production for application of bio-jet fuel and bio-naphtha

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ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.