Sustainable and Highly Efficient Recycling of Plastic Waste into Syngas via a Chemical Looping Scheme

Converting plastic waste into valuable products (syngas) is a promising approach to achieve sustainable cities and communities. Here, we propose for the first time to convert plastic waste into syngas via the Fe₂AlO_<i>x</i>-based chemical looping technology in a two-zone reactor. The Fe₂AlO_<i>x</i>-based redox cycle was achieved with the pyrolysis of plastic waste in the upper zone, followed by the decomposition and thermal cracking of hydrocarbon vapors, and the oxidation and water splitting in the lower zone (850 °C) enabled a higher carbon conversion (81.03%) and syngas concentration (92.84%) when compared with the mixed feeding process. The iron species could provide lattice oxygen and meanwhile act as the catalyst for the deep decomposition of hydrocarbons into CO and the accumulation of deposited carbon in the reduction step. Meanwhile, the introduced water would be split by the reduced iron and deposited carbon to further produce H₂ and CO in the following oxidation step. A high hydrogen yield of 85.82 mmol/g HDPE with a molar ratio of H₂/CO of 2.03 was achieved from the deconstruction of plastic waste, which lasted for five cycles. This proof of concept demonstrated a sustainable and highly efficient pathway for the recycling of plastic waste into valuable chemicals.