Enhanced CO2 gasification of polyethylene terephthalate using a two-stage gasification process to produce CO-rich and tar-deficient syngas.

This study demonstrates that a two-stage gasification process consisting of a fluidized bed gasifier followed by a tar-cracking reactor packed with activated carbon enables stable and efficient CO2 gasification of polyethylene terephthalate. Conventional fluidized-bed CO2 gasification typically suffers from low CO2 conversion due to limited gas-solid residence time and the inherently low reactivity of CO2. In contrast, the present two-stage configuration significantly enhances CO2 utilization by first fixing polyethylene terephthalate-derived tar on activated carbon and subsequently promoting its reaction with CO2, thereby intensifying the Boudouard reaction. Under 100 vol% CO2, the system achieved outstanding performance, producing CO-rich syngas with CO concentrations up to 80 vol% and CO yields of 1.03 kg per kg of dry feed, while simultaneously reducing char formation. The carbon utilization efficiency reached 57-64 %, indicating that a substantial portion of supplied CO2 was successfully converted into syngas carbon. Moreover, when the tar-cracking reactor temperature exceeded 800 °C, the condensed tar yield decreased to 3-7 g per kg of dry feed, confirming that this configuration effectively mitigates tar-related issues that have traditionally limited CO2 plastic gasification. These findings show that the two-stage process overcomes the intrinsic limitations of CO2 fluidized-bed gasification and offers a practical route for simultaneous polyethylene terephthalate recycling and CO2 utilization. The significant improvement in CO2-to-CO conversion further highlights the potential of CO2 gasification as a promising method for producing high-purity CO while contributing to carbon circularity.