One-Pot Photocatalytic Cleavage of Lignin β–O–4 Models by Dehydrogenation–Hydrogenolysis
Zhenlong Song, Yuzhen Hu, Song Li, Jianguo Liu, Xinghua Zhang, Longlong Ma, Lungang Chen, Qi Zhang
Abstract
Valorizing lignin into valuable chemicals requires the selective breaking of a large number of C–O bonds found in the β–O–4 structure. In this study, we present a one-pot strategy that utilizes two NiO/TiO 2 catalysts for the photocatalytic depolymerization of β–O–4 alcohols. The S-1.6%NiO/TiO 2 catalyst is used for the dehydrogenation of β–O–4 alcohols at 450 nm. Then, the L-0.8%NiO/TiO 2 catalyst is employed for the hydrogenolysis of β–O–4 ketones at 365 nm. Remarkably, the dehydrogenation–hydrogenolysis tandem reaction can be conducted in one pot, which affords high yields of ketones and phenols (up to 89%) from β–O–4 alcohols. Additionally, the L-0.8%NiO/TiO 2 catalyst prepared in this article is the smallest NiO/TiO 2 photocatalyst reported to date, and the size of NiO in the S-1.6%NiO/TiO 2 catalyst is even small enough to enter the lattice of TiO 2 . We successfully regulated the reaction selectivity by controlling the loading method and the amount of NiO. Our work offers a promising solution for efficiently cleaving target bonds in lignin and provides insights into the design of efficient photocatalysts.