Thermochemical Conversion of Polyvinyl Chloride (PVC) in the Presence of Fe3O4 and CO2 for Syngas Production

Thermochemical energy recovery (i.e., syngas production) from waste plastic valorization is more challenging compared to the recovery from biomass due to the relatively high stability of plastic. Thermal degradation of polyvinyl chloride (PVC) assisted by Fe₃O₄ was carried out to investigate the feasibility of using Fe₃O₄ to facilitate enhanced syngas production (H₂ and CO). The enhanced generation of H₂ and CO from thermolysis of PVC/Fe₃O₄ was more obvious in CO₂ atmosphere than N₂ atmosphere. In the presence of Fe₃O₄, the generation of CO from PVC thermolysis began at 560 °C, which was different from the CO generation from powdered activated carbon (PAC) thermolysis that initiated at the temperature over 720 °C. This substantial production of CO was attributed to redox reaction between Fe₃O₄ and CO₂. A small amount of Fe₃O₄ (Fe₃O₄/PVC = 0.01) was able to trigger a CO₂-looping gasification, increasing CO production in the temperature of 560-720 °C (up to 7.1 mole% at 680 °C). On the other hand, further addition of Fe₃O₄ at a ratio of 0.5 enhanced the concentration level of CO, particularly in the latter half of thermolysis (up to 4.5 mole % at 900 °C). Good adsorption capability of biochar from PVC/Fe₃O₄ thermolysis was also demonstrated to achieve over 77% removal efficiency of methylene blue.