Ni5Fe5/Al2O3 catalytic hydrogenolysis of lignin: mechanism investigation and selectivity regulation

• Published in: Green chemistry : an international journal and green chemistry resource : GC 2023-10, Vol.25 (19), p.7782-7793
• Main Authors: Shen, Zhensheng, Wang, Wei, Pan, Lun, Huang, Zhenfeng, Zhang, Xiangwen, Shi, Chengxiang, Ji-Jun Zou
• Format: Article
• Language: English
• Subjects: Alcohols; Aluminum oxide; Bimetals; Catalysts; Green chemistry; Hydrogenolysis; Intermediates; Lignin; Lignocellulose; Sawdust; Sinapyl alcohol
• ISSN: 1463-9262; 1463-9270
• DOI: 10.1039/d3gc01988h

The development of novel catalysts to regulate product selectivity and insight into the mechanism of lignin hydrogenolysis are important for the comprehensive utilization of lignocellulose. Herein, we present a non-precious bimetallic catalyst Ni5Fe5/Al2O3 with improved catalytic performance relative to commercial Pd/C and Ni10/Al2O3 for hydrogenolysis of woody sawdust. In particular, the selectivity of propylguaiacol and propylsyringol is 79.1%. We developed kinetic experimental studies on β-O-4 model compounds and directly monitored the coniferyl alcohol or sinapyl alcohol intermediates in the reaction system for the first time. This directly demonstrates the lignin hydrolysis reaction pathway with simultaneous breakage of Cα–OH and Cβ–O. In the catalytic system, the reason for the difference in selectivity between Ni5Fe5/Al2O3 and other catalysts is their different hydrogenation pathways for intermediates coniferyl alcohol or sinapyl alcohol. Our work provides both an efficient catalyst and insight into understanding and regulating the mechanism of lignin hydrogenolysis.