Air gasification of polyethylene terephthalate using a two-stage gasifier with active carbon for the production of H₂ and CO

Polyethylene terephthalate was gasified using a two-stage gasifier composed of a fluidized bed gasifier and tar-cracking reactor and air as the gasifying agent. The main challenge was to overcome problems such as equipment clogging caused by the condensable compounds (tars) generated during polyethylene terephthalate gasification. Active carbon was applied to the two-stage gasifier to reduce tar. As a result of gasification, we did not experience any problems caused by tar, thereby obtaining a clean producer gas. Active carbon played a crucial role in increasing H₂ production and reducing the tar content. The tar-cracking reactor temperature and equivalence ratio turned out to have a significant influence on the gas quality. The gas produced from the gasification of polyethylene terephthalate had high contents of H₂ and CO. At the tar-cracking reactor temperature of 844 °C and an equivalence ratio of 0.27, a producer gas containing 22 vol% H₂, 25 vol% CO, and 7 mg/Nm³ of tar was obtained. Considering the high amount of O in polyethylene terephthalate compared with that in polyolefin, CO production from the two-stage air gasification of polyethylene terephthalate appeared to be very attractive when the process was implemented on a commercial scale.