Effects of metal oxides on the pyrolysis of poly(ethylene terephthalate)

Metal oxides as Ca(OH)2, NiO, Fe2O3 or TiO2 showed different effects on the pyrolysis of PET. The experiments were carried out at 700 °C in a helium atmosphere using a laboratory equipment. Ca(OH)2 led to the hydrolysis of the PET and the following decarboxylation of the resulting terephthalic acid to benzene in a high amount up to 31 wt.%. By this means a yield of 77% related to the terephthalic acid content in the PET. The addition of Fe2O3 led to a similar but weaker effect. Nickel oxide showed less influence on the pyrolysis products of PET. With titanium dioxide considerably less gaseous products were obtained. When a mixture of Ca(OH)2 and NiO was used PET was converted to synthesis-gas with a high hydrogen and carbon monoxide content and a gas amount of about 70%. The experiments with mixtures of Fe2O3 or TiO2 with Ca(OH)2 showed little differences to the experiments with pure Ca(OH)2.