Green and sustainable manufacture of chemicals from biomass: state of the art

The various strategies for the valorisation of waste biomass to platform chemicals, and the underlying developments in chemical and biological catalysis which make this possible, are critically reviewed. The option involving the least changes to the status quo is the drop-in strategy of complete deoxygenation to petroleum hydrocarbons and further processing using existing technologies. The alternative, redox economic approach, is direct conversion of, for example, carbohydrates to oxygenates by fermentation or chemocatalytic processes. Examples of both approaches are described, e.g. fermentation of carbohydrates to produce hydrocarbons, lower alcohols, diols and carboxylic acids or acid catalyzed hydrolysis of hexoses to hydroxymethyl furfural (HMF) and subsequent conversion to levulinic acid (LA), γ-valerolactone (GVL) and furan dicarboxylic acid (FDCA). Three possible routes for producing a bio-based equivalent of the large volume polymer, polyethylene terephthalate (PET) are delineated. Valorisation of waste protein could, in the future, form an important source of amino acids, such as L-glutamic acid and L-lysine, as platform chemicals, which in turn can be converted to nitrogen containing commodity chemicals. Glycerol, the coproduct of biodiesel manufacture from triglycerides, is another waste stream for which valorisation to commodity chemicals, such as epichlorohydrin and acrolein, is an attractive option.