Thermochemical bioalcohol production from butyric acid using methanol as an in-situ hydrogen source

Abstract

Biobutanol is a promising substitute for gasoline, and thermochemical processes offer a solution to the low yields caused by microbial deactivation in conventional biological methods for butanol production. Given that butyric acid, a primary intermediate from the anaerobic digestion of food waste, has a suitable carbon chain length for butanol production, this study proposes a novel thermochemical approach for biobutanol production through the hydrogenation of food waste-derived butyric acid using methanol as an in-situ hydrogen source. A calcium oxide-based catalyst was synthesised from industrial waste by incorporating steel slag as the calcium source and a polyester textile as the functional support. The synergistic effect of calcium oxide and oxygen-functionalized supports enhanced methanol dehydrogenation at moderate temperatures (<450 °C), facilitating butanol conversion. The reaction occurred in a single step, wherein methanol and butyric acid were chemisorbed onto the catalyst, followed by the simultaneous dehydrogenation of methanol and hydrogenation of chemisorbed butyric acid. This process achieved a maximum C4-C7 alcohol yield of 67.2% within 1 min at 440 °C, with 81.1% selectivity toward 1-butanol. Compared with conventional hydrogenation processes, this strategy simplifies production steps and provides a scalable and sustainable route for biobutanol synthesis.