Thermo-catalytic degradation of low density polyethylene over clinoptilolite - The effect of carbon residue deposition

Thermo-catalytic degradation of low density polyethylene (PE-LD) was studied in the presence of the natural zeolite - dinoptilolite. The effect of carbon deposition on the catalyst activity was also investigated. It was observed that the PE-LD degradation process over dinoptilolite proceeded at shorter time and lower temperature. The catalyst activity tests were carried out in argon in a stainless steel batch reactor at temperature, up to 410 °C at ambient pressure. The decomposition products were classified into three groups: gases, liquids and solid-like residues. The liquid products were analysed by gas chromatography coupled with mass spectrometry GC/MS method. A shift towards lower molecular mass products was observed in reactions with fresh dinoptilolite. The application of this catalyst in thermal degradation of PE-LD leads to lower alkane to alkene ratios and inhibits the formation of cyclohydrocarbons. The presence of carbon deposit on the surface of re-used dinoptilolite leads to higher ratio of saturated to unsaturated hydrocarbons, but neither did it significantly change reaction temperature nor the phase composition of the reaction products.