posters 5th Asia-Pacific NMR Symposium 2013

NMR Characterization of Biomass-PET Pyrolysis Products (#151)

Kwang Hyun Ko 1 , Aditya Rawal 2 , Veena Sahajwalla 1
  1. SMART Centre, School of Material Science and Engineering, University of New South Wales, Sydney
  2. Mark Wainwright Analytical Centre, University of New South Wales, Sydney

The energy recovery of biomass and plastics through pyrolysis is increasingly seen as crucial to sustainable development. Pyrolysis of solid materials such as biomass, plastics, hazardous and medical wastes under a vacuum or inert gas environment can also yield functional materials for applications such as electrodes for metallurgical applications and absorbents for organic pollutants.  In the current study, the degradation kinetics and structural evolution of a blend of biomass (macadamia nut shell or coconut shell) with polyethylene terephthalate (PET) during the co-pyrolysis have been analysed by a combined solid state NMR and TGA approach. The rapid structural changes that occur in the temperature range between 400 oC to 500 oC are readily monitored by solid state 13C and 1H MAS NMR. The 13C NMR spectroscopy with CP-TOSS indicates that the co-pyrolysis accelerates the degradation of the PET fraction. This accelerated degradation of PET is highest for a biomass to PET blend ratio of 80:20. Solid State 1H saturation recovery experiments on the co-pyrolyzed blends indicate the formation and stabilization of a higher concentration of reactive radical species as compared to individually pyrolyzed biomass or PET. The structural insights from the NMR measurements were closely followed by analysing the thermal degradation kinetics by TGA. The TGA revealed that the presence of a strong synergistic effect during the co-pyrolysis between the biomass and the PET. This effect which is assigned to the enhanced radical formation is shown to not only speed up the degradation of the PET but also promote the crosslinking mechanisms that enhance formation of polycyclic aromatic hydrocarbons which are crucial to enhancing the residue yield in the final high temperature ( >600 oC) pyrolysis products.