State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology

开发和利用可再生生物质资源是实现二氧化碳减排的有效途径。而生物质结构复杂，整体反应性和利用率较低。木质素是自然界中唯一具有高能量密度的可再生芳香族聚合物，其转化和利用在全球范围内引起了广泛关注。然而，木质素结构的复杂性、连接方式的不确定性、侧链连接的稳定性以及反应片段不可避免的再缩合，使得将木质素解聚成生物燃料或芳香化学品成为一项艰巨的挑战。催化氢解技术可将木质素转化为高选择性、高收率的酚类单体。但是木质素催化解聚过程中化学键的定向剪切，产物与结构之间的转化机理仍不清晰。本工作针对木质素的催化氢解生产高值化学品的最新研究进展，重点总结了木质素的催化氢解过程中催化剂及其高值化学品产物间的耦合关联，着重讨论了不同催化剂体系对木质素解聚产物过程机理的影响，尤其对于金属基催化剂，综述了贵金属基催化剂、过渡基金属催化剂、水滑石催化剂和金属有机框架催化剂对于产物分布影响的最新进展，并进一步总结了不同催化剂存在的问题和转化机制；同时木质素加氢催化裂解过程中溶剂是促进木质素溶解、加速传热传质、促进反应物和催化剂在反应器中均匀分散的关键。本工作并对木质素液化的主要溶剂，例如水、醇类和新型溶剂体系对木质素的解聚效应进行综述。最后，就领域所面临的机遇和挑战进行了总结和展望，为木质素高效定向转化与高值化利用提供了理论参考。

The development and utilization of renewable biomass resources is an effective way to achieve CO2 reduction. Biomass has a complex structure with low overall reactivity and utilization. Lignin is the only renewable aromatic polymer with high energy density in nature, and its conversion and utilization have attracted much attention worldwide. However, the complexity of the lignin structure, the uncertainty of the linkages, the stability of the side-chain connections, and the inevitable recondensation of the reactive fragments make the depolymerization of lignin into biofuels or aromatic chemicals a formidable challenge. Catalytic hydrogenolysis technology converts lignin into highly selective, high-yield phenolic monomers with high heating value, low oxygen content, and high carbon utilization of the product. However, the mechanism of the conversion between products and structures remains unclear with respect to the directed bond shearing during the catalytic depolymerization of lignin. In this paper, in view of the latest research progress on the catalytic hydrogenolysis of lignin for the production of high-value chemicals. We focus on the catalytic hydrogenolysis of lignin to summarize the coupling correlation between the catalysts and their products of high-value chemicals and focus on the influence of different catalyst systems on the process mechanism of lignin depolymerization products. For metal-based catalysts in particular, a detailed review of recent advances in the effects of noble metal-based catalysts, transition metal-based catalysts, hydrotalcite catalysts, and metal-organic framework catalysts on product distribution is presented. And further summarized the problems and conversion mechanisms of different catalysts. Meanwhile, the solvent in the lignin catalytic hydrogenolysis cracking process is the key to promote lignin dissolution, accelerating the heat and mass transfer, and promoting the homogeneous dispersion of reactants and catalysts in the reactor. In this paper, the main solvents for lignin liquefaction, such as water, alcohol, and new solvent systems, are reviewed for their depolymerization impact on lignin. And further, outline the effect of the solvent system on the properties of lignin conversion products. Nevertheless, there are still many difficulties in the catalytic hydrogenolysis of lignin for the preparation of high-value chemicals. The complexity of the macromolecular structure of lignin, the directed depolymerization of the C−O and C−C structures is still difficult, and the preparation of efficient catalysts as well as the mechanism of directional regulation of the products are still to be further investigated. Due to the insolubility of lignin, no solvent system that can completely dissolve lignin has been found yet; secondly, the research on the solvent effect is still only in the preliminary exploration stage. Novel technology for favorable conversion of lignin is still only at the stage of laboratory research. And the efficient conversion of renewable lignin into valuable chemicals and fuels is of great significance in solving the energy crisis and slowing down global warming, and at the same time, it will help our country to realize the energy-dependence transition from oil to renewable biomass. So finally, the opportunities and challenges facing the field are summarized and outlooked, providing a theoretical reference for efficient targeted conversion and high-value utilization of lignin.

国家自然科学基金杰出青年科学基金 ( 52125601) 资助

刘菊平, 唐紫玥, 陈应泉, 王贤华, 陈汉平, 杨扬, 杨海平. 木质素催化氢解制备高附加值化学品研究进展[J]. 燃料化学学报（中英文）, 2024, 52(7): 945-958.

LIU Juping, TANG Ziyue, CHEN Yingquan, WANG Xianhua, CHEN Hanping, YANG Yang, YANG Haiping. Recent advances in the preparation of high-value-added chemicals by catalytic hydrogenolysis of lignin[J]. Journal of Fuel Chemistry and Technology, 2024, 52(7): 945-958.