Pyrolysis study of a PVDC and HIPS-Br containing mixed waste plastic stream: Effect of the poly(ethylene terephthalate)

摘要

Pyrolysis of poly(vinylidene chloride) (PVDC), brominated flame retardant containing high impact polystyrene (HIPS-Br), poly(ethylene) (PE), poly(propylene) (PP), poly(styrene) (PS) mixed were performed in the presence and absence of poly(ethylene terephthalate) (PET) under atmospheric pressure at 430 ℃ using a semi-batch operation. We attempted the dehalogenation (Cl, Br) of chlorinated and brominated liquid hydrocarbons using iron oxide and calcium hydroxide based carbon composites for the production of halogen free liquid hydrocarbons. The presence of PET in the plastics mixture of PP/PE/PS/PVDC/HIPS-Br affected significantly the formation of pyrolysis products and the pyrolysis behavior of plastic mixture. We observed the following effects of PET on the pyrolysis of PP/PE/PS/PVCD/HIPS-Br mixed plastic pyrolysis: (ⅰ) The yield of liquid product was decreased and the formation of gaseous products increased during the thermal decomposition, (ⅱ) the waxy residue was observed in addition to the solid carbon residue and (ⅲ) use of calcium hydroxide carbon composite (CaH-C) removed the major portion of chlorine and bromine content from the liquid products from PP/PE/PS/PVDC/HIPS-Br pyrolysis, however in the presence of PET, the combination of calcium hydroxide carbon composite (CaH-C) and iron oxide carbon composites could not dehalogenate the liquid products effectively. X-ray diffraction analysis reveals the presence of antimony compounds in carbon and wax residues.