Malonic acid is a high-value dicarboxylic acid with strong industrial demand, used in diverse products including automotive coatings, flavor and fragrances, biodegradable polymers, and anodic oxide films in batteries. Yet its current production heavily relies on petrochemical feedstocks.
Fermentation of biomass-derived sugars is emerging as an alternative route to produce high-value organic acids like malonic acid (MA). Although direct MA fermentation has been suggested in several studies, its highest reported titer remains far below that of 3-hydroxypropionic acid, a bio-based C3 platform molecule that can serve as a precursor for MA production.
In a new paper, University of Wisconsin-Madison researchers at the Center for Advanced Bioenergy and Bioproducts Innovation (CABBI) report the first systematic study for sustainable production of malonic acid via oxidation of 3-hydroxypropionic acid (3-HP) with a Pd/Carbon catalyst.
The effects of oxidant type (O2 and H2O2), pH, and temperature on the reaction chemistry were comprehensively evaluated. Guided by experimental observation and DFT-calculated thermochemical energetics, reaction networks for 3-HP oxidation with both oxidants were proposed and validated through kinetic modeling. MA was identified as the primary oxidation product, while further oxidation yields acetic acid and oxalic acid.
The kinetic model validated the network, displaying excellent agreement (R2 > 0.95). Kinetic observations also enabled a direct comparison between O2 and H2O2 and revealed their distinct behaviors. The model was further developed into a temperature-time map, providing insight into conditions that maximize MA production. Malonic acid selectivity of 56.9 % and yield of 50.5 % were achieved at 3 bar oxygen, equimolar NaOH:3-HP ratio, and 50 °C.
This framework of 3-HP oxidation will be a good starting point for those interested in MA production via 3-HP.
This work was funded by CABBI, a U.S. Department of Energy-funded Bioenergy Research Center, with a grant from the DOE Office of Science, Biological and Environmental Research Program.
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