Catalytic Upgrading of Holocellulose-Derived C 5 and C 6 Sugars

Biorefineries are a new concept in chemical manufacturing in which naturally occurring, sustainable biomass resources such as forestry and agricultural waste are converted to diverse fuel and chemical product streams, akin to the processing of non-renewable fossil fuels by petrochemical refineries. Polysaccharides are attractive potential feedstocks for biorefineries, with the transformation of C5 and C6 sugars offering routes to the production of fine, bulk, and platform chemicals typically produced via petrochemical routes. The transformation of biomass-derived building blocks will require different processes to those currently employed in the petrochemical industry, wherein highly functional biomolecules are selectively deoxygenated to their target product, which requires new classes of catalyst that are compatible with hydrophilic, bulky substrates. Here, we review recent advances in the design and development of catalysts and processes for C5–C6 sugar reforming into chemical intermediates and products and highlight the challenges of aqueous phase operation and catalyst evaluation, in addition to process considerations such as solvent and reactor selection.