Catalytic refining lignin into toluene over atomically dispersed Cu/Ni dual sites
Xin Zhao, Changzhi Li, Jie Wen, Qiang Qian, Zirong Shen, Haipeng Yu, Xin Zhou, Fengxia Yue, Ruiqi Fang, Yingwei Li, Tao Zhang
Abstract
Lignin refining still suffers from great challenges of selective depolymerization and cleavage of stubborn C‒C linkages. Here, a robust atomically dispersed Cu/Ni-SA@HNC catalyst is fabricated for super-selective hydrogenolysis of lignin and model compounds via an unusual “preferential Cα–Cβ bond cleavage in β-O-4 linkages” pathway, affording toluene in yield up to 75.7% from β-O-4 model compounds, and up to 33.7 ± 1.6 wt% (nine parallel experiments) from poplar lignin. The catalyst exhibits high stability, and the scale-up potential is demonstrated by the high space-time yield of toluene (33.7 g·gcat−1·h−1) in continuous flow reaction of β-O-4 model compound. The origin of the extraordinary selectivity towards Cα–Cβ bond cleavage rather than C‒O bond cleavage in β-O-4 model compounds is uncovered. This work conquers the major challenges in lignin valorization by using non-noble dual-metal single-atom catalyst, not only showcasing the application perspective of atomically dispersed catalysts in biopolymer refinery, but also providing a cost-efficient, petroleum independent solution to valuable commodity chemicals. Lignin refining continues to face major challenges in achieving selective depolymerization and breaking resistant C–C bonds. In this work, the authors design a robust atomically dispersed Cu/Ni-SA@HNC catalyst that enables highly selective hydrogenolysis of lignin and model compounds through an unconventional pathway involving preferential Cα–Cβ bond cleavage in β-O-4 linkages.