Heterogeneous Catalysis for the Conversion of Sugars into Polymers

The synthesis of commodity polymers from biomass presents interesting challenges and opportunities for new catalytic chemistries. Starting from glucose, reaction pathways to a variety of monomers for commodity polymers are presented. The first step for each pathway is the isomerization of glucose to fructose. This reaction can now be accomplished in aqueous media with hydrophobic, large pore molecular sieves that contain Lewis acid sites as catalysts. A typical catalyst is a pure-silica molecular sieve having the zeolite beta topology and containing a small amount of framework Sn4+ (Sn-Beta). Dehydration of fructose into 5-hydroxymethylfurfural (HMF) provides a convenient path that can lead to 2,5-furandicarboxylic acid (FDCA) for the synthesis of polyethylene furanoate (PEF) or purified terephthalic acid (PTA) (via Diels-Alder reactions) for the synthesis of polyethylene terephthalate (PET). Recent progress on the dehydration of lactic acid could open new routes to acrylic acid and acrylonitrile that are used to produce polyacrylic acid and polyacrylonitrile, respectively, provided more selective catalysts for the retro-aldol deconstruction of fructose are developed.