Selective hydrogenolysis of aryl ethers over a nitrogen-doped porous carbon supported Ni–CeO2 catalyst at low temperature

Abstract

Selective hydrogenolysis of aryl ethers to produce aromatic compounds is a key strategy for lignin valorization. The use of non-noble-metal catalysts to realize the cleavage of C–O ether bonds under mild conditions has been of considerable research interest recently. We herein report the synthesis of a nitrogen-doped porous-carbon-skeleton-supported Ni–CeO₂ catalyst (Ni–CeO₂/CN). The synergistic effect between Ni and CeO₂ species led to the Ni–CeO₂/CN catalyst having a high activity and selectivity for the cleavage of C–O ether bonds at a low reaction temperature. In particular, the Ni–CeO₂/CN catalyst showed excellent effectiveness in the hydrogenolysis of benzyl phenyl ether (α-O-4 bonds), and the full conversion was achieved after 2 h at a temperature of 60 °C, with phenol and toluene as the sole reaction products. In addition, the conversion of more robust β-O-4 ether bonds in 2-phenoxy-1-phenylethanol reached up to 100% with the yield of ethylbenzene and phenol at 150 °C for 2.5 h being 60.2% and 68.3%, respectively. The reusability-experiment results indicate that Ni–CeO₂/CN maintained a high catalytic activity in five reaction runs, making this a promising route for C–O ether bond cleavage under mild conditions.