Given the high 100g/ L titer 2,3-butanediol (BDO) can be obtained from fermentation of sugars, it appears as a potential feedstock for extending the network of bio-based chemicals and fuels. Here, catalytic upgrading of 2,3-BDO to methyl-ethyl-ketone and butadiene products was demonstrated in aqueous media and bio-2,3-BDO, respectively. Additionally, a two-step process was developed for the conversion of 2,3-BDO fermentation broth to n-butene-rich olefins fuel precursors via Methyl-Ethyl-Ketone (MEK) intermediate. This unique 2-step approach allows for operating with aqueous 2,3-BDO feedstock and as such it does not require energy intensive separation of 2,3-BDO from the fermentation broth. Unlike other approaches, the conversion of 2,3-BDO n-butene-rich olefins can be conducted without H<sub>2</sub>. However, operating under H<sub>2</sub> allows for higher carbon efficiency (~83% olefins selectivity at 98% conversion). Experiments conducted with model aqueous 2,3-BDO feedstocks and a real 2,3-BDO fermentation broth enabled to identify impurities (e.g., glycerol) from the fermentation broth that led to catalyst deactivation due to coking. The jet fuel produced from n-butene-rich olefins oligomerization followed by hydrogenation presented fuel properties consistent with ASTM specifications. Overall, the process and catalysts show promise to be part of a marketable process for jet and diesel fuel production from the 2,3-BDO fermentation broth.

Catalytic conversion of 2,3-butanediol to fuels and chemicals

ACS Spring 2022

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