engleski

Thermogravimetric Analysis and Kinetic Study of Mixed Plastic Waste

The biggest producer of plastic products today is the packaging industry which makes up for almost 40% of European plastic converter demand. In one year roughly 80% of produced plastic packaging in Europe turns into waste. In 2016, for the first time, a larger share of overall collected post- consumer plastic waste in Europe was recycled (31%) than landfilled (27%), while the rest was energy recovered (42%) mostly by incineration. Pyrolysis, a thermochemical degradation, is a promising technology used to valorise plastic waste by converting it into valuable products, such as fuels and chemicals. Most common polymers used in the packaging industry are high and low- density polyethylene (HDPE and LDPE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC) and polyethylene terephthalate (PET). From those, PVC and PET are not preferable components in the feedstock for pyrolysis process because of the formation of corrosive and toxic compounds. As pyrolysis reactor design is conditioned by prediction of the thermochemical behaviour and kinetic parameters of feedstock, in this research thermogravimetric analysis (TGA) was carried out on various mixtures of waste plastics containing HDPE, LDPE, PP, and PS in ratios that are determined by the actual plastic mix in Europe. TGA was carried out in a nitrogen atmosphere over a set of heating rates (5, 10, 15 and 20 °C/min) within a temperature range 40−600 °C. Kinetic analysis was performed using the isoconversional (Kissinger–Akahira–Sunose) method. Aim of this paper was to investigate the kinetics of the pyrolysis process of polymer mixtures using Ni- or Fe- based catalysts on γ- Al2O3 as a support. The results of the kinetic analysis showed that degradation mechanism of the polymer mixtures was complexed because of the variation in apparent activation energy with the conversion. The value of apparent activation energy for actual plastic mix (22% HDPE, 31% LDPE, 35% PP, 12% PS) was in range 180.8−208.3 kJ/mol. With the addition of catalyst Fe/γ-Al2O3 it lowered to 161.5−182.8 kJ/mol, and to 170.6−183.9 kJ/mol with Ni/ γ- Al2O3 catalyst.

plastic waste ; thermochemical pyrolysis ; dynamic thermogravimetric analysis ; kinetic study ; catalyst

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