Aqueous Electrocatalytic Hydrogenation Depolymerization of Lignin β-O-4 Linkage via Selective Caryl–O(C) Bond Cleavage: The Regulation of Adsorption,Journal of the American Chemical Society

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Aqueous Electrocatalytic Hydrogenation Depolymerization of Lignin β-O-4 Linkage via Selective Caryl–O(C) Bond Cleavage: The Regulation of Adsorption
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2024-11-05 , DOI: 10.1021/jacs.4c12220
Yuanqing He ₁ , Xu Zeng ₂ , Zhuoran Lu ₁ , Shiheng Mo ₁ , Qizheng An ₃ , Qinghua Liu ₃ , Yulu Yang ₁ , Wu Lan ₄ , Shuangyin Wang ₁ , Yuqin Zou ₁

Affiliation

The cleavage of the benzene–oxygen (C_aryl–O(C)) bond of the lignin β-O-4 linkage is expected to relieve condensation of the degradation product and improve the product value. Nevertheless, the electrochemical breaking of the C_aryl–O(C) bond has not been achieved yet due to the high dissociation energy (∼409 kJ mol^–1) and the easy over-reduction of aromatic compounds. Here, we report an aqueous electrochemical reduction strategy for breaking C_aryl–O(C) bonds via the regulation of molecular adsorption. The density functional theory (DFT) calculations and quartz crystal microbalance (QCM) measurements reveal that the residual Cu(I) in the CuO electrocatalyst enhances the adsorption of the 2-phenoxy-1-phenylethyl alcohol (PPE) by the C_aryl–O(C) bond and lowers the energy barrier of the protons attacking the oxygen atom in the β-O-4 linkage. Thus, compared to the Cu electrocatalyst (with a hydroquinone yield of 47.4% and a benzyl alcohol yield of 24.8%), the CuO nanorod exhibits a much higher yield of hydroquinone (95.3%) and benzyl alcohol (88.6%) at a potential of −0.4 V vs reversible hydrogen electrode (RHE) in an undivided cell. Moreover, the reaction pathway and the cleavage of the C_aryl–O(C) bond are identified through a combination of in situ synchrotron-radiation Fourier transformed infrared spectroscopy (SR-FTIR) and DFT calculations. This effective method is utilized for poplar lignin electrolysis, yielding 10.9 wt % of guaiacylglycerol, with an outstanding selectivity of >63.0%. This work provides an efficient and mild method of cleavage of C_aryl–O(C) bonds in lignin valorization.

中文翻译：

水电催化 Caryl-O（C）键裂解木质素 β-O-4 键的氢化解聚：吸附的调节

木质素 β-O-4 键的苯-氧（C_芳基-O（C））键的断裂有望缓解降解产物的缩合并提高产品价值。然而，由于高解离能（∼409 kJ mol^–1）和芳香族化合物容易过还原，C_芳基-O（C）键的电化学断裂尚未实现。在这里，我们报道了一种通过调节分子吸附来破坏 C_芳基-O（C）键的水性电化学还原策略。密度泛函理论（DFT）计算和石英晶体微天平（QCM）测量表明，CuO 电催化剂中残留的 Cu（I）增强了 C_芳基-O（C）键对 2-苯氧基-1-苯乙醇（PPE）的吸附，并降低了 β-O-4 键中攻击氧原子的质子的能垒。因此，与铜电催化剂（对苯二酚产率为 47.4%，苯甲醇产率为 24.8%）相比，CuO 纳米棒在 -0.4 V 电位下对苯二酚（95.3%）和苯甲醇（88.6%）的产率要高得多，而不是在未分割的电池中。此外，通过原位同步辐射傅里叶变换红外光谱（SR-FTIR）和 DFT 计算的组合来确定反应途径和 C_芳基-O（C）键的裂解。这种有效的方法用于杨木木质素电解，产生 10.9 wt % 的愈创木酰甘油，具有出色的选择性 >63.0%。这项工作提供了一种在木质素增值中裂解 C_芳基-O（C）键的有效和温和方法。

更新日期：2024-11-05

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