Controlling generation of benzenes and polycyclic aromatic hydrocarbons in thermolysis of polyvinyl chloride in CO2

Abstract

This study emphasizes the control of benzene derivatives and polycyclic aromatic hydrocarbons (PAHs) in thermolysis of polyvinyl chloride (PVC) using CO2. To this end, the generation of benzenes and PAHs from the thermolysis of PVC in N-2 was characterized and all experimental findings from the thermolysis of PVC in N-2 were used as the reference value to configure the role of CO2 in the thermolysis of PVC. The formation of hydrogen chloride (HCl) followed by the subsequent dechlorination in the thermolysis of PVC in N-2 resulted in the high yield of charring compounds, providing a favorable condition for forming benzene derivatives and PAHs. However, the thermal degradation of PVC in CO2 showed the genuine thermal degradation patterns. For instance, despite the presence of the source for oxygen, the formation of CO at temperatures higher than 600 degrees C was observed in the thermolysis of PVC in CO2, suggesting that some unknown reactions between hydrocarbons from the thermolysis of PVC and CO2 are initiated to form CO. In addition to these unknown reactions, the enhanced thermal cracking induced by CO2 was observed. Two identified roles of CO2 during the thermolysis of CO2 was only limited at temperatures higher than 600 degrees C. However, despite no precise description for the mechanistic role of CO2 at this stage of study, the formation of benzene derivatives and PAHs was effectively controlled in the presence of CO2 at temperatures higher than 480 degrees C. Thus, these empirical findings in this study are necessary to further be investigated in the future, which offers a great venue offering a new means for modifying and/or controlling the harmful chemical species.