Upcycling of polyphenylene oxide into 2,6-dimethyl aniline via depolymerization and amination over a Pt/CeO2 catalyst

Abstract

Upcycling of plastic waste into N-containing compound is a novel and attractive strategy for its disposal and will opens up a promising direction for the production of value-added amines. Herein, an efficient strategy for the depolymerization-amination of polyphenylene oxide (PPO) into 2,6-dimethyl aniline is developed over a simple Pt/CeO₂ catalyst. The C–O linkages of PPO can be selectively broken, producing 2,6-dimethyl phenol and then hydrogenated and aminated to 2,6-dimethyl cyclohexylamine over the Pt/CeO₂ catalyst. Finally, 2,6-dimethyl aniline was produced with high selectivity through the dehydrogenation of 2,6-dimethyl cyclohexylamine in the same catalyst. Toluene can be used as the hydrogen-acceptor in the dehydrogenation step and enhance the selectivity of target product. Single N-containing compound, 2,6-dimethyl aniline, is obtained and separated after HCl treatment. Meanwhile, the Pt/CeO₂ catalyst exhibit remarkable stability and can sustainably catalyze the synthesis of 2,6-dimethyl aniline in several cycles.