Production of biomass-derived monomers through catalytic conversion of furfural and hydroxymethylfurfural

The synthesis of biomass-derived monomers has received great attention in recent years, motivated by the depletion of fossil fuels and environmental issues. Moreover, the intrinsic functionality within the biomass or biomass-derived chemicals has great potential to produce new types of monomers containing multiple acid or alcohol groups, thereby leading to materials with novel properties. Given their versatile functional groups and easy production from cellulose/hemicellulose, furfural and hydroxymethylfurfural were regarded as very important biomass-derived platform chemicals through which multiple monomers can be produced via heterogeneous catalysis. In the current review, recent development in heterogeneous catalysis for the production of 6 bio-based monomers, furfuryl alcohol, 2,5-bis(hydroxymethyl)furan, 2,5-bis-(hydroxymethyl)tetrahydrofuran, 1,5-pentanediol, 1,6-hexanediol, and 2,5-furandicarboxylic acid, from furfural and hydroxymethylfurfural is reviewed and summarized. The major challenge is how to efficiently and selectively convert specific functional group(s) in furfural and hydroxymethylfurfural during the production of these monomers. Additionally, catalyst stability issues need to be addressed due to necessity of using hot water as reaction medium and high tendency of carbonaceous deposit formation on catalyst surface. The current review mainly focuses on efforts of catalytic site design and modification, including selection of metal/support, use of synergy between metal and support, tuning metal size, use of inverse catalysts, adding catalytic promoters, constructing bimetallic sites, etc., to realize efficient, selective and stable production of bio-based monomers from furfural and hydroxymethylfurfural.