Selective valorization of lignin to C8 phenols over atomically dispersed Ni on basic AlN

Lignin is mainly composed of three basic C9 phenolic monomers, which makes it a formidable challenge to selectively produce C8 phenolic monomers, precursors for the ethylbenzene and styrene, due to intricate C–O and C–C cleavages. Here, we introduce a Ni 0.5% /AlN catalyst, featuring atomically dispersed Ni on a basic AlN support. The catalyst yields 52.7 % relative phenolic monomers with an unparalleled selectivity of 58.7 % for C8 phenolic species (Phenol, 4-ethyl, and Phenol, 4-ethyl-2-methoxy). The inherent basic sites within the AlN support crucially facilitate the formation of quinone intermediates, subsequently directed by single-atom Ni into C8 phenolic monomers. The catalyst showcases robust recyclability over five cycles, because of the strong interactions between Ni and AlN support. This study reveals a synergistic interplay between single-atom Ni and the basic support, paving a transformative pathway for the selective valorization of lignin.