An Investigation of the Thermal Degradation Mechanisms of a Waste Tire Through Chemical Analysis Including Hydrocarbons, Benzene Derivatives, and Polycyclic Aromatic Hydrocarbons (PAHs) at High Temperature

Abstract

Previous work has focused on a series of fundamental Thermal Gravimetric Analysis (TGA) studies using representative atmospheres found in Waste-to-Energy (WtE) boilers. Those studies were done for waste tires and their major constituents, such as Styrene-Butadiene Copolymer (SBR) and Poly-Isoprene (IR). The outcome has been the elucidation of the likely mechanism responsible for initial decomposition, final product and byproduct formation. To extend that understanding to a more practical level, a flow through apparatus has been used to test waste tire samples in the temperature range of 500 degrees C-800 degrees C. A chemical analysis in this temperature range has been performed to compare the thermal degradation mechanism and air pollutant generation in low temperature regimes. The release of chemicals from a tubular quartz reactor containing a tire sample has been determined experimentally using a GC/MS. Significant Volatile Organic Carbons (VOCs) including benzene derivatives, PAHs, and Hetero-N containing PAHs were observed, This study identifies and quantifies the concentration levels of various hazardous air pollutants, and provides new data for the overall development and validation of detailed reaction mechanisms that can describe the thermal degradation of waste tires. This information will enable the development of mitigation strategies that can address those levels of pollutant species.