Direct amination of poly(p-phenylene oxide) to substituted anilines over bimetallic Pd–Ru catalysts

Abstract

Chemical upcycling of plastic waste offers a promising opportunity for synthesizing value-added products. Despite its potential, transforming poly(phenylene oxide) (PPO) into nitrogen-based chemicals remains underexplored. To that end, we report the direct conversion of PPO to dimethylanilines over bimetallic Pd–Ru/CNT in a mixture of octane and aqueous ammonia. In a one-pot manner, PPO is initially converted into substituted phenols, and then is aminated, yielding 30% dimethylanilines over Pd₇Ru₃/CNT under optimum conditions. The bimetallic catalyst outperforms its monometallic equivalents. Transmission electron microscopy (TEM), powder X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDX) unveiled the features of well dispersed and small-sized metallic nanoparticles. Control experiments using deuterium indicated a high reliance of hydrogen and water for the amination step and the hydrogenolysis step, respectively. Furthermore, we demonstrated product isolation through a straightforward acid–base treatment and extraction. This work introduces a viable route for upcycling PPO into valuable nitrogen-containing compounds.