Pyrolysis studies of PP/PE/PS/PC/HIPS-Br plastics mixed with PET and dehalogenation (Br, Cl) of the liquid products

摘要

Pyrolysis of polypropylene (PP)/polyethylene (PE)/polystyrene (PS)/poly(vinyl chloride) (PVC)/high impact polystyrene with brominated flame retardant (HIPS-Br) plastics mixed with poly(ethylene terephthalate) (PET) was performed at 430℃ under atmospheric pressure using a semi-batch operation. The presence of PET in the pyrolysis mixture of PP/PE/PS/PVC/HIPS-Br affected significantly the formation of decomposition products and the decomposition behavior of the plastic mixture. We observed the following effects of PET on the pyrolysis of PP/PE/PS/PVC/HIPS-Br mixed plastics: (ⅰ) the yield of liquid product decreased and the formation of gaseous products increased; (ⅱ) a waxy residue was formed in addition to the solid carbon residue; (ⅲ) the formation of SbBr_3 was not detected in liquid products; (ⅳ) the yield of chlorinated branched alkanes increased as well as vinyl bromide and ethyl bromide were formed. The use of calcium carbonate carbon composite (Ca-C) completely removed the chlorine and bromine content from the liquid products during PP/PE/PS/PVC/HIPS-Br pyrolysis, however in the presence of PET, the catalytic experiment (Ca-C, 8 g) yielded liquid products containing 310 ppm of Br and 20 ppm of Cl. In addition, the Ca-C increased the yield of liquid products about 3-6 wt.%, as well as enhanced the gaseous product evolution and decreased the yield of residue. The halogen free liquid hydrocarbons can be used as a feedstock in a refinery or as a fuel.