Recycling of polymers by pyrolysis

The pyrolysis of plastic waste, scrap tires and other polymeric materials in a fluidized bed has been carried out based on a scale up program (laboratory plants 70 g/h, 500 g/h, 3000 g/h, and pilot plant 20-50 kg/h). The fluidized bed shows short residence times and high heat and mass transfers, and is heated indirectly up to 600 800 OC. In the case of poly(methylmethacry1ate) (PMMA) or polystyrene as feedstock up to 97 w t . % of the monomer can be recovered. Other polymers give a more unspecific product spectrum. Depending on the process parameters between30 and 60 % of the polymeric material could be recovered as oil which is comparable to that of a mixture of light benzene and bitumious coal tar if the pyrolysis gas is used as fluidizing gas. The other fractions are gas anda residue containing fillers and impurities (heavy metals). The gas fraction contains mainly methane, ethane, ethene, and propene, the oil fraction benzene, toluene, xylene, and naphthalene.