Product Distribution at Different Conversions of Polypropylene (PP)

Plastics, derived from petrochemicals, have replaced metals and ceramics due to their low cost and lightweight nature. This has led to a surge in plastic production, resulting in increased plastic waste, with only 9% properly recycled. A Remade Project about chemical recycling, aims to address this issue. Our lab focuses on one of the four overall tasks: the development of mechanistic understanding of process components, where we work with the chemical degradation process known as pyrolysis. Pyrolysis decomposes organic materials into gases and oils useful for energy production. However, a lack of kinetic understanding of plastic pyrolysis restricts feedstock changes without compromising product quality. Therefore, we use a GCxGC system to analyze pyrolysis products, enhancing peak separation and yielding a three-dimensional chromatogram. We have previously observed that the total yield of polypropylene pyrolysis products increases with temperature. The current objective is identifying product distribution of non-catalytic PP pyrolysis at set temperature levels, in this case 400 degrees Celsius, but with different conversions. While GCxGC conditions don't affect pyrolysis, they do influence chromatogram quality. In the end, we made three conclusions. Cooling the reactor and using the cryotrap allowed this study to be possible. The major products identified were 2,4-Dimethylheptene, Pentane, and 2-methylPentene at observed conversion levels. And the information from the flame ionization detector and mass spectrometer allowed identification of these peaks in terms of carbon number and group (boiling point and polarity). Further steps involve quantifying these peaks for weight percentage and exploring different conditions and inputs to advance chemical recycling and reduce plastic waste.