Volatile products of catalytic thermal decomposition of waste poly(ethylene terephthalate)

Abstract

Poly(ethylene terephthalate), commonly abbreviated as PET, is one of the most widely used thermoplastics in everyday life thanks to its excellent physical and chemical properties. Due to the slow biodegradability of PET wastes and the fact that its consumption is still increasing, there is a growing interest on recycling of post-consumer PET wastes to reduce its volume in land-fill sites. Among the recycling methods, chemical recycling is the most acceptable method in environmental terms as it leads to the formation of the materials from which the polymer is originally made or other raw materials. Moreover, the recycling of polymer waste by thermal processes (pyrolysis) can be an important source of hydrocarbons for the petrochemical industry, contributing to the environmental protection. However, this process requires high quantity of energy due to the poor thermal conductivity and endothermicity of plastics. To decrease thermal decomposition costs of polymeric material wastes, cheap catalysts have become of the most interest from a global recycling point of view. In the present work, two kinds of fly ash (coal and biomass fly ash) were tested as catalysts to examine their influence on the volatile compounds emitted during thermal decomposition process of waste PET in selected conditions: 400ºC in N2 atmosphere. Moreover, two methods of mixing sample with each fly ash were performed to compare their effects. The analysis was performed using gas chromatography method with different detectors and spectrophotometric method.