Controllable depolymerization of lignin using carbocatalyst graphene oxide under mild conditions

FUEL

卷:267

Article

Zeng, Jijiao^1,2  Tong, Zhaohui¹  Bao, Hanxi¹  Chen, Nusheng¹  Wang, Fei¹  Wang, Yigui³  Xiao, Dequan³ 

[1] Univ Florida, Dept Agr & Biol Engn, 1741 Museum Rd, Gainesville, FL 32611 USA

[2] Sichuan Univ Sci & Engn, Coll Chem Adn Environm Engn, 180 Xueyuan St,Huixing Rd, Zigong 643000, Sichuan, Peoples R China

[3] Univ New Haven, Ctr Integrat Mat Discovery, Dept Chem & Chem Engn, 300 Boston Post Rd, West Haven, CT 06516 USA

关键词: Lignin depolymerization;    Graphene oxide;    Enol ether;    Carbocatalyst;    Energy diagram;   

DOI  :  10.1016/j.fuel.2020.117100

来源: Elsevier

【 摘 要 】

Many efforts have been devoted to depolymerizing lignin to high-value aromatic monomers. However, a controllable and complete lignin inter-unit bond cleavage remains difficult because of the randomness in lignin structure and low selectivity in catalysis. Herein, we demonstrate that a sole carbocatalyst graphene oxide (GO) can selectively oxidize aryl- and alkyl-hydroxyl groups of lignin without the presence of any additional oxidizers, leading to lignin degradation under mild conditions. The results from lignin dimers, lignin oligomers, and organosolv lignin indicate that the depolymerization is catalyzed via an oxidative mechanism through an enol ether intermediate, a stable intermediate that has been chemically isolated here. Quantum chemistry calculations at the density functional theory level indicate that the phenolic -OH group in lignin facilitates the formation of radical cations and thus prohibits ring opening reactions, leading to the complete conversion of lignin dimers to guaiacol through the enol ether intermediate.

【 授权许可】

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