Polyethylene Terephthalate Gasification Using CO2: Impact of SFCC Catalyst Contact Mode and Amount

Abstract The influence of spent fluid catalytic cracking (sFCC) catalyst on CO2-assisted gasification of polyethylene terephthalate (PET) was investigated at 900 °C using a semi-batch fixed-bed reactor. The effects of catalyst amount and contact mode on the release of synthesis gas (syngas) and char yields were studied. sFCC catalysis increased the maximum syngas yield by about 45% and energy yield by 60% in comparison to non-catalytic gasification. High syngas energy was extracted during CO2-assisted catalytic gasification, revealing the efficacy of sFCC and CO2 in PET conversion. The efficiency comparison with different amounts of catalyst revealed that the catalyst is more effective in a quasi-in-situ mode wherein the catalyst was located downstream of the feedstock sample at approximately 1.5 to 2 cm. This mode resulted in effective thermal cracking of the sample without posing limitations on the solid-solid heat transfer. Catalytic gasification using CO2 produced 1.2 times more combustible gas than the feedstock mass, implying CO2 consumption of more than 0.2 grams to create combustible gases (such as H2 and CO). The results reveal that co-utilization of PET wastes, sFCC catalyst, and CO2 can help provide energy-efficient carbon sequestration and waste management for sustainable energy recovery.