Dechlorination of chlorine compounds in poly(vinyl chloride) mixed plastics derived oil by solid sorbents

The degradation of poly(ethylene) (PE) (8 g)/poly(vinyl chloride) (2 g) at 430 °C, poly(propylene) (PP) (8 g)/PVC (2 g) at 380 °C, and poly(styrene) (PS) (8 g)/PVC (2 g) at 360 °C into fuel oil was carried out in a glass reactor under atmospheric pressure by batch operation. The purpose of this study is to determine the composition of the products of the degradation of PVC mixed plastics and to remove chlorine compounds from products with suitable sorbents. The organic chlorine compounds were distributed in the boiling point (bp) range of 36-174 °C (equivalent to the bps of n-C₆ to n-C₁₀) for PE/PVC and PP/PVC and 36-195 °C for PS/PVC. These compounds are thought to be produced by the reaction between the hydrogen chloride originating from PVC and the hydrocarbons obtained from the degradation of PE, PP, and PS. The degradation of the PP/PVC mixture was also carried out in the presence of a silica-alumina (SA1) catalyst, which is known as an effective catalyst for the degradation of hydrocarbons, and iron oxides (FeOOH, Fe₂O₃, and Fe₃O₄), as chlorine sorbents. Compared to thermal degradation, the SA1 catalyst accelerated the rate of degradation and lowered the bp of products, and the iron oxides FeOOH and Fe₃O₄ decreased the chlorine content in the oil to a very low level. We suggest that the chlorine removed from the products of degradation of PVC mixed plastics are fixed in the form of iron compounds such as ferrous chloride.