Metal-organic framework-derived CuO catalysts for the efficient hydrogenolysis of hardwood lignin into phenolic monomers

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2023-11, Vol.11 (44), p.2389-2382
• Main Authors: Xu, Qian, Wang, Qiang, Xiao, Ling-Ping, Li, Xiao-Ying, Xiao, Xi, Li, Meng-Xin, Lin, Meng-Ran, Zhao, Yu-Man, Sun, Run-Cang
• Format: Article
• Language: English
• Subjects: Catalysts; Cleavage; Copper; Copper oxides; Hardwoods; Hydrogenolysis; Lignin; Lignocellulose; Metal-organic frameworks; Monomers; Phenolic compounds; Phenols; Propanol
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/d3ta04927b

The selective reductive catalytic deconstruction (RCD) of lignin into phenolic monomers provides the possibility for making the full use of lignocellulose. However, the widespread use of precious metal catalysts and the harsh reaction conditions present the challenge of poor industrial utilization in the current research. Herein, we report a metal-organic framework (MOF)-derived copper oxide catalyst (CuO/c-UiO-66), which exhibits superior catalytic properties in the RCD of hardwood lignin and affords high yields (up to 42.8 wt%) of monomeric phenols via the C-O bond scission. The mechanistic reactions using lignin model compounds reveal that phenolic compounds with propyl or propanol end chains are selectively produced during the catalytic hydrogenolysis reaction. The enhanced catalytic reactivity is attributed to the synergy of acid and base sites of the catalyst, which facilitates the C-O bond cleavage process. The new insights of this study provide guidance toward the rational design of Cu-based catalysts for RCD of lignin. The synergistic effects of the fabricated CuO/c-UiO-66 catalyst and hydrogen lead to the efficient scission of C-O bonds of the methoxylated β- O -4′ intermediates, transforming hardwood lignins into monophenols.