Selective Catalytic Oxidation of Humins to Low-Chain Carboxylic Acids with Tailor-Made Polyoxometalate Catalysts

摘要

For the first time, a selective catalytic conversion of thermally induced side products (humins) from biomass valorization to short-chain carboxylic acids like formic acid and acetic acid is reported. Very interestingly, we found that homogeneous polyoxometalate catalysts could selectively oxidize humins from sugar-derived levulinic acid production to formic acid and acetic acid under very mild conditions in a simple monophasic aqueous approach. This green and sustainable process offers a very cost-effective and sustainable way for the conversion of undesired humins and benefits from its low reaction temperature (90-120℃) and its tunable product distribution. By variation of process parameters and chemical composition of the POM structures, we could control both product selectivity and humin conversion. Furthermore, catalyst recycling over three batches has been successfully carried out.