Cohydrothermal carbonization of waste polyvinyl chloride and wood chip for dechlorination

The co-hydrothermal carbonization (Co-HTC) of polyvinyl chloride (PVC) film and wood chip (WC) was conducted at 200-260oC in an autoclave filled in air or nitrogen for the chemical recycling of wastes with dechlorination of PVC. Effects of the Co-HTC temperature and the oxidation reaction during the Co-HTC on the decomposition behaviors were investigated. The percentage decomposition in nitrogen atmosphere increased with increasing the reaction temperature and reached 76.1% at 260oC. The percentage decompositions in nitrogen were several percent higher than those in air. The synergistic effect of PVC and WC for the decomposition was observed at 220oC in N2 . When the Co-HTC was performed in air, decomposition was suppressed, indicating the increase in hydrochar yield. The dechlorination yield was determined from the Cl content in the recovered PVC after the Co-HTC reaction. Under nitrogen atmosphere conditions, the dechlorination yield increased slightly with increasing the temperature. At a carbonization temperature of 260oC, the dechlorination yield of PVC was about 40%.