Feedstock recycling of polymers by pyrolysis in a fluidised bed

Feedstock recycling of polymers is an attractive option to recycle the increasing amount of plastic wastes and respond to restrictions for waste disposal in a lot of countries. Different processes are investigated such as degradation of plastics to monomers, pyrolysis into monomers and oil, gasification into syngas. Pyrolysis of mixed plastic wastes and elastomers is a cost-effective process to recover feedstocks for the petrochemical industry. The Hamburg process, using an indirectly heated fluidised bed, can be varied to produce mainly monomers, aliphatic hydrocarbons, or aromatics. At temperatures of 450 degreesC, poly(methyl methacrylate) (PMMA) is depolymerised to more than 98% of the monomer. The influence of fillers on the monomer yield has been studied. Polystyrene as feed gives up to 75% of styrene and 10% of oligomers. First demonstration plants are running for feedstock recycling of PMMA in a fluidised bed. (C) 2004 Elsevier Ltd. All rights reserved.