PNNL

Abstract

Selective upcycling of polyolefin waste has been hampered by the relatively high temperatures required to cleave the C-C bonds at reasonably high rates. We present a distinct approach that uses a highly ionic reaction environment to increase the polymer reactivity and lower the energy of ionic transition states. Combining endothermic cleavage of the polymer C-C bonds with exothermic alkylation reactions of the cracking products enables full conversion of polyethylene and polypropylene to liquid isoalkanes (C6-C10) at temperatures below 70 °C. Both reactions are catalyzed by a Lewis acidic species generated in a chloroaluminate ionic liquid. The alkylate product forms a separate phase and is easily separated from the reactant catalyst mixture. The process can convert unprocessed post-consumer items, such as disposable face masks, food packaging and polyethylene bottles, to high-quality liquid alkanes with high yields.