Tuesday, March 15, 2016
Making plastics from agricultural wastes and carbon dioxide
Approximately 50 megatons of polyethylene terephthalate (PET) are produced annually, which represent about 18% of world polymer production. This material is derived to refine oil and natural gas and its carbon footprint is about 6 kg CO2 per kg of plastic, thus is considered an important source of contamination.
Production of biobased plastics has been considered an alternative to PET. Polyethylene furandicarboxylate (PEF) is a biobased polymer made from 2-5-Furandicarboxylic acid (FDCA) and ethylene glycol. This polymer has a superior physical properties to PET, as low gas permeability and better heat resistance due to its glass transition temperature and melting point. Additionally, CO2 emissions are less in its production than in PET production.
The conventional route of PEF production is well known, fructose derived from plants is converted into Furanics and subsequent recovery and upgrading into 5- hydroxymethylfurfural (HMF) and HMF ethers. These compounds are oxidized to FDCA and polymerized with ethylene glycol to make PEF. PEF present great attributes to be used as plastic, but its production at scale is not affordable.
In the last week, Banerjee and co-workers of Oxford University published in Nature a sustainable way to produce PEF from agricultural wastes and CO2. They used Furfural derived from agricultural wastes. Production of FDCA (one of the monomers used to generate PEF) from furfural and CO2 needs expensive chemicals and energy. This team found an alternative to these chemicals: carbonate.
They used caesium carbonate at intermediate-temperature (200 to 350ºC), to promote C-H carboxylation followed by protonation to convert 2-furan carboxylate (FC) with CO2 to FDCA.
This study provide a new strategy to reduce CO2 emissions, utilize agricultural wastes and production of FDCA, which can be applied in many areas, including PEF synthesis. PEF has a great potential to be used in plastic industry and compete with PET.
1. Banerjee, A., Dick, G. R., Yoshino, T., & Kanan, M. W. (2016). Carbon dioxide utilization via carbonate- promoted C–H carboxylation. Nature, 531(7593), 215-219.
2. Beckman, E. J. (2016). Sustainable chemistry: Putting carbon dioxide to work. Nature, 531(7593), 180-181.