Pyrolysis Behavior of Polyethylene Terephthalate (PET) Plastic Waste Under the Presence of Activated Montmorillonite Catalyst: TGA and EGA-MS Studies

Production of PET-based plastics, which are mainly used for food and beverage packaging, continuously increases in amount annually, which has been widely reported to cause various severe environmental issues. Pyrolysis is one of the possible methods to convert PET plastic wastes into valuable products such as benzene-rich oil. Unfortunately, its larger-scale development is still hindered and challenging to pursue since it produces acidic compounds as the main product, such as terephthalic acid, which is undesirable because it can cause blockage of the reactor pipeline and corrosion. In this work, catalytic pyrolysis of PET has been investigated over a thermally activated montmorillonite (AMMT) catalyst to increase the feasibility of PET recycling for energy production. The thermal and catalytic pyrolysis behavior of PET under AMMT was comprehensively investigated by TGA and EGA-MS analyses. TGA analysis results indicated that the presence of AMMT reduced the onset and maximum decomposition temperature of PET pyrolysis. Moreover, the isothermal TGA result exhibited that the presence of AMMT could significantly reduce the amount of the produced carbonaceous residue. From EGA-MS analysis, it can be obtained that the presence of AMMT indeed changed the amount and distribution of evolved gaseous products, as indicated by the difference in the extracted ion thermogram intensities.