Direct Electrosynthesis of 2-Butanone from Fermentation Supernatant

Abstract

Fossil-based products strongly attribute to the CO2-footprint of the chemical industry, which must decline to restrain the consequences of the anthropogenic climate change. This can be achieved by sustainable production processes from bio-based resources. We propose a sustainable production process for methy-ethyl-ketone (MEK), an abundantly used solvent. The process includes the biotechnological conversion of biomass to acetoin and the subsequent electrochemical reduction to MEK. Direct electrocatalytic reduction of acetoin in a fermentation supernatant without prior purification mitigates process complexity and increases process efficiency. We show that production of MEK from a fermentation broth is feasible with a slightly decreased yield compared to model solution experiments. Further, constant current experiments reveal a yield and selectivity dependence of the fermentation broth pH, which is not apparent in the model solution. Starting from 50 g L−1 acetoin fermentation broth, we reach approximately 50 % yield of MEK with a product selectivity of 80 %. The conversion of acetoin is limited due to side product formation and hydrogen evolution reaction. This work contributes to the development of sustainable solvents to decrease CO2-emission in the chemical industry.