Catalytic Furfural/5-Hydroxymethyl Furfural Oxidation to Furoic Acid/Furan-2,5-dicarboxylic Acid with H₂ Production Using Alkaline Water as the Formal Oxidant

Abstract

Furfural and 5-hydroxymethyl furfural (HMF) are abundantly available biomass-derived renewable chemical feedstocks, and their oxidation to furoic acid and furan-2,5-dicarboxylic acid (FDCA), respectively, is a research area with huge prospective applications in food, cosmetics, optics, and renewable polymer industries. Water-based oxidation of furfural/HMF is a lucrative approach for simultaneous generation of H 2 and furoic acid/FDCA. However, this process is currently limited to (photo)electrochemical methods that can be challenging to control, improve, and scale up. Herein, we report well-defined ruthenium pincer catalysts for direct homogeneous oxidation of furfural/HMF to furoic acid/FDCA, using alkaline water as the formal oxidant while producing pure H 2 as the reaction byproduct. Mechanistic studies indicate that the ruthenium complex not only catalyzes the aqueous oxidation but also actively suppresses background decomposition by facilitating initial Tishchenko coupling of substrates, which is crucial for reaction selectivity. With further improvement, this process can be used in scaled-up facilities for a simultaneous renewable building block and fuel production.

Ultra-low voltage bipolar hydrogen production from biomass-derived aldehydes and water in membrane-less electrolyzers

“…Catalytic H2 generation from biobased aldehydes can also be accompanied by the production of valuable by-products, such as carboxylic acids. In the past years, the transformation of aldehydes to carboxylic acids along with H2 evolution was reported from several non-Faradaic reactions, including base-, 17,18 heterogeneous-, [19][20][21] and homogeneous [22][23][24][25] -catalyzed processes (RXN 3). However, these reactions generally require a high concentration of base (>>1 M OH − ) or elevated temperature (>100 ℃) with both aldehyde and H2O as proton sources in the formation of H2.…”

Electrocatalytic valorization of 5-hydroxymethylfurfural coupled with hydrogen production using tetraruthenium-containing polyoxometalate-based composites

“…Chem. A, 2022, 10,19963 These catalysts were reported to effectively catalyze the oxidation of HMF to FDCA in strong alkali electrolyte via path II (Scheme 1). Interestingly, DFF is also a high value-added platform chemical and can be used either as a monomer, or as starting material in the synthesis of furan-urea resins, foams, binders, and pharmaceuticals.…”

Sustainable catalysis with fluxional acridine-based PNP pincer complexes

“…24a and b). 80 Furfural and HMF are bio-based renewable feedstocks, and their oxidation products are important for the implementation of future green chemical industry. 81,82 It was found that while in the presence of other pyridine-based pincer complexes furfural and HMF degraded to unidentifiable polymers, the acridine-based complexes selectively oxidized them with high yields (495%), while suppressing decomposition.…”