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Chemistry and Industry of Forest Products ›› 2023, Vol. 43 ›› Issue (4): 115-126.doi: 10.3969/j.issn.0253-2417.2023.04.016

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Progress in the Preparation and Transformation of Lignin-based Aromatic Aldehydes

Geliang XIE(), Xianjun ZHOU, Chengyu DONG, Wei CHEN, Lujiang XU(), Zhen FANG   

  1. College of Engineering, Nanjing Agricultural University, Nanjing 210095, China
  • Received:2022-04-25 Online:2023-08-28 Published:2023-08-26
  • Contact: Lujiang XU E-mail:1693538003@qq.com;lujiangxu@njau.edu.cn

Abstract:

Aromatic aldehydes were important raw materials for the synthesis of fine chemicals such as dyes, spices, pesticides and drugs. Lignin was the second largest component in lignocellulosic biomass, and was the only renewable resource for producing aromatic compounds. Catalytic oxidation could transform lignin into highly functionalized aromatic aldehydes(e.g., p-hydroxybenzaldehyde, vanillin, syringaldehyde, etc.) under mild conditions, which was regarded as one of the effective ways to realize the resource utilization of lignin. Firstly, the structural characteristics and depolymerization mechanism of lignin were introduced, and the effects of lignin structure on the production of aromatic aldehydes were summarized and discussed. Then, recent progress in the preparation of aromatic aldehydes by oxidative depolymerization of lignin was introduced in detail from the methods of catalytic oxidative depolymerization methods(e.g., wet oxidation and alkaline nitrobenzene oxidation, catalytic oxidative depolymerization with homogeneous and heterogeneous catalysts, photocatalytic oxidation and electrocatalytic oxidation) and types of catalysts(e.g., metal salts and metal porphyrins, heteropoly acids and other homogeneous catalysts, metal oxides and perovskite oxides and other heterogeneous catalysts). Moreover, the upgrading and conversion of aromatic aldehydes into high value-added products such as 2-methoxy-4-methylphenol, aromatic nitrile, aromatic amides and new organic polymer materials were further summarized. Finally, the existing problems in the current research on lignin oxidative depolymerization were summarized, and the possible development direction in the future was proposed, which laid a foundation for lignin oxidative depolymerization and high value-added utilization.

Key words: lignin, catalytic oxidation, aromatic aldehydes, synthesis, conversion

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