Recycling polymeric wastes by means of pyrolysis

Different polymeric wastes, which include materials from the automobile industry, such as tyres, automobile shredder residues (ASR) and sheet moulding compound (SMC), and materials from municipal solid wastes (MSW), such as cardboard, tetrabrik and plastics (LDPE, PP, PS, PET and PVC), pure and mixed, have been pyrolysed in a 3.5 dm(3) autoclave at 500degreesC for 30 min in a nitrogen atmosphere. The amount and characteristics of the solid, liquids and gases obtained are presented. The suitability of the different materials for the pyrolysis recycling process is discussed. It is concluded that pyrolysis is a very promising technique for recycling tyres, SMC, one type of ASR (heavy ASR), and LDPE, PP and PS, either pure or mixed; with all of them valuable solid, liquid and gaseous products are obtained in pyrolysis. On the contrary, light ASR, tetrabrik and cardboard do not yield valuable products in the pyrolysis process and therefore their recycling by pyrolysis is not of interest, except as a way of volume reduction. PET and PVC turned out to be troublesome in the pyrolysis experiments; for a proper study of their recycling by pyrolysis other operating conditions and installations are required. (C) 2002 Society of Chemical Industry.