Thermo gravimetric kinetics of polypropylene degradation on ZSM-12 and ZSM-5 catalysts

The growth in waste plastics discarded each year is causing significant environmental problems. Polypropylene, mainly used to make car parts, pieces of furniture, fibers, fabric and film, represents 22 wt% of thermoplastic demand in the world. An alternative to this problem is chemical recycling in order to have a cheap source of useful chemicals and energy. In this work, the kinetics of catalytic thermo gravimetric degradation of polypropylene used in domestic furniture was investigated using ZSM-12 and ZSM-5 catalysts. The ZSM-12 catalyst demonstrated lower activation energy and higher activity in comparison with thermal degradation without a catalyst. A ZSM-12 zeolite content of 30 wt% in the mixture of polymer was sufficient to obtain high degradation conversions. The application of model-free Vyazovkin kinetics showed that to obtain 95% polypropilene degradation on ZSM-12 in 60 min required a temperature of 328 °C. This temperature was 55 °C lower than the thermal degradation for pure polymer. The ZSM-12 activity was more efficient than that of ZSM-5 under the same operational conditions.