(633f) Exploring the Potential of Co-Upcycling PS and PE for Enhanced Aromatics Production

With the continuous increase in the volume of waste plastic, plastic upcycling is a viable option as it is a fast and efficient process that produces high value products. In this work, the potential of co-upcycling polystyrene (PS) and polyethylene (PE) for enhanced aromatics production is explored in thermal reactor and microwave reactor. In the conventional thermal reactor, the plastics PS and PE were converted using ZSM-5 catalyst operated at reaction temperature of 400^oC. Moreover, the interaction between PS and PE to enhance the aromatics production was studied by in-situ FTIR. While PS is capable of producing high level of aromatics, the main product from PE was straight-chain hydrocarbons. It was observed that co-upcycling of PS and PE can enhance the overall yield of aromatics and reduce the required reaction temperature. Based on these findings, a reaction scheme was proposed to describe the interaction of the plastic feedstock. When PS is present in the feedstock, PE straight chain radicals can easily crosslink with the benzene radicals produced from cracking of PS. Therefore, the concentration of monocyclic aromatics hydrocarbons was found to be significantly higher with the mixed plastic compared to pure PS and LDPE. The main product of pure LDPE and PS were alkanes and polycyclic hydrocarbons, respectively. Hence, combining two plastics in pyrolysis generates synergy that leads to the formation of specific group of desirable products.

Moreover, this work features the newly microwave-driven catalytic upcycling of plastics. Microwave-driven reactor setups are known for their selective and rapid heating of materials. Therefore, the reaction temperature can be reduced even further as only the plastic-catalyst interface was heated. However, the hurdle was that plastics, unlike catalyst, are generally transparent to microwave. The ZSM-5 supported catalysts were developed for microwave-driven co-upcycling of PS and PE and demonstrated the high selectivity for aromatics.