Hydrocarbons obtained by waste plastic pyrolysis: Comparative analysis of decomposition described by different kinetic models

Thermal degradation of waste polymers has been investigated in a batch reactor at temperatures of 410, 430 and 450 °C using atmospheric pressure without catalysts. Raw materials were real wastes (plastics, paper, etc.), but considerably differences have been found among them. According to FTIR analysis raw materials contained polyethylene, polypropylene, polystyrene and polyamide 6. The composition of plastics (polyethylene, polypropylene, polystyrene, etc.) was different, however in case of one sample (W-3) significant motor oil content has been demonstrated. Different hydrocarbon fractions were produced in the cracking reactions: gases, pyrolytic oil and heavy oil. The polymer destruction was described based on different reaction kinetic approaches (yields of volatile products, theory of continuous distribution, and number of scissions per an average polymer chain) and reaction kinetic parameters (e.g. activation energy of the degradation) have been calculated then results were compared. The values obtained have also been compared to literature data and try to reflect the complexity of pyrolysis process. Pyrolysis reactions could be well described by the used models. The calculated results well approached the data obtained from the literature, but due to the difference in raw material composition, the calculated kinetic parameters have been different, too.

► Thermal degradation of waste polymers has been investigated.
► The depolymerisation of plastic wastes has been realized in a batch reactor.
► Reaction kinetic parameters were calculated by different kinetic model approaches.