Pyrolysis Products of Tetra Pack in Different Oxygen Concentrations

The tetra pack is one of the principal materials in municipal solid wastes (MSW). The amount of waste tetra pack is over 6000 tons per year in Taiwan. The components of tetra pack are kraft paper (about 70 wt %), low-density polyethylene (LDPE, about 25 wt %), and aluminum foil (about wt 5%), generally. Accordingly, its conversion to useful fuels as well as the recycling aluminum foil has become a worthy goal from not an economic, but also from an environmental standpoint. In this study, the experiments for the partial oxidation of tetra pack were carried out with a thermogravimetric analysis (TGA) reaction system. The pyrolysis reactions of tetra pack were performed in four different oxygen concentrations (C O2 ) of 5.4, 10.4, 14.8, and 21.0% for analyzing the pyrolysis products. The gaseous products were collected at room temperature (298 K) and analyzed by gas chromatography (GC). The residues were collected at the pyrolysis temperatures 575, 656, 700, 730, and 1073 K and analyzed by elemental analyzer, and X-ray powdered diffraction (XRPD). The cumulated masses and the instantaneous concentrations of gaseous products corresponding to the different oxygen concentrations were obtained under the experimental conditions. The recovery of total gaseous products based on the mass of tetra pack sample was over 88% for four different oxygen concentrations. The major gaseous products of tetra pack pyrolysis reaction were CO 2 , CO, H 2 O, and hydrocarbons (HCs). The hydrocarbons mainly consist of low molecular paraffins and olefins (C 1-5 ). The percentages of C 1-5 relative to the total hydrocarbons gases were about 69.9, 71.1, 74.3, and 68.8 wt % for tetra pack pyrolysis in C O2 = 5.4, 10.4, 14.8, and 21.0%, respectively. In the XRPD analysis, the results indicated that a high-purity aluminum foil could be obtained from the final residues.