Catalytic pyrolysis of waste packaging polyethylene using AlCl3-NaCl eutectic salt as catalyst

Catalytic pyrolysis is an attractive and promising way to recycle waste plastics. In this paper, AlCl3-NaCl eutectic salt was used as the catalyst to pyrolyze waste polyethylene (WPE), and its catalytic activity was studied. Thermogravimetry (TG), gas chromatography-mass spectrometer (GC–MS) and Fourier transform infrared spectroscopy (FTIR) were applied to investigate the pyrolysis behavior of WPE in the presence of AlCl3-NaCl eutectic salt during the catalytic pyrolysis. Subsequently, the char separated from the pyrolysis residue were characterized by scanning electron microscope (SEM), energy dispersive spectrometer (EDS), nitrogen adsorption and desorption testing, respectively. The results show that our strategy allows for the pyrolysis of WPE in the presence of molten AlCl3-NaCl eutectic salt, which can not only reduce the initial pyrolysis temperature (below 200 °C) significantly but also play a key role in increasing the reaction rate. Accordingly, it is a safe and environmentally benign treatment of “white pollutions” by both reducing energy consumption of pyrolysis process and alleviating the environmental pollutions. Besides, another advantage of using the AlCl3-NaCl eutectic salt as catalyst in pyrolysis of WPE is that the components of the heavy oil in the liquid products was much more reduced and no olefin was generated thus narrowing the composition distribution and improving their utilization value for further use. What’s more, the char separated from residue contains many pore structures with a BET surface area of 218-277 m2 g−1. As results, this strategy provides a new avenue for the applications of eutectic salt for catalytic pyrolysis of waste plastics.