07.10.19 – Depolymerizing biomass using protection group chemistry

“For his discovery of the acetal functionalization of lignin and carbohydrates, which prevent degradation reactions during the extraction of these fractions from plant matter. Acetal formation notably enables the isolation of lignin, which can easily be upgraded to useful chemicals, with the potential to greatly increase the productivity of biorefineries and of pulp and paper processes.”

After atmospheric carbon dioxide, lignocellulosic biomass is the second-largest source of renewable carbon on our planet. This makes biomass a very attractive source of sustainable alternatives to fossil-derived chemicals. The production of various chemicals from biomass usually involves the depolymerization of biomass’s three constituent polymers: cellulose and hemicellulose, which are both polysaccharides; and lignin, which is an aromatic polymer. The molecules resulting from this depolymerization can be catalytically upgraded to either direct or indirect substitutes for petrochemicals. In depolymerization, the biggest challenge is usually not achieving the desired reaction, but rather avoiding being outcompeted by other, detrimental reactions. These degradation reactions are especially pronounced during lignin deconstruction which has systematically prevented its successful upgrading to chemicals.

Jeremy Luterbacher’s and his research group have discovered that the use of functionalization with acetals, both during lignin extraction and polysaccharide depolymerization, can reversibly “trap” stabilized intermediate molecules, and facilitate their high-yield upgrading. Notably, they have shown that under the right conditions, extracted lignin, which is normally very difficult to utilize, could be catalytically upgraded at high yields to one or two major products. This particular chemistry has the potential to greatly enhance the productivity of biorefineries and pulp and paper processes.