摘要
Dehalogenation is a significant process in recycling of WEEE plastics as energy or feedstock. Steam gasification in the presence of molten carbonates is a promising means for recycling WEEE as the plastics they contain can be converted into main product of syngas that can be recycled, and valuable metals are left for further processing. In the process, the organic halogen compounds can be expected recovered as safe and stable inorganic salts. In the study, typical chlorine containing WEEE plastic of PVC was studied by the steam gasification in the presence of molten carbonates at the temperature of 625 °C. The dechlorination stage was investigated by thermo-gravimetric analysis and differential thermal analysis besides the steam gasification. The thermal decomposition of PVC proceeded in two steps, the first step is dechlorination in the low temperature region around 200-400 °C, and the second step is decomposition of the remainder from the first step. The dechlorination in the steam gasification was mainly affected by the steam flow rate, temperature and carbonates. Results indicate that most of the chlorine can be removed in the process directly that the steam gasification is expected to be used as a feasible method for converting WEEE plastics into clean gaseous products together with valuable metals recovery.