Nitrogen-Doped Carbon-Modified Cobalt-Nanoparticle-Catalyzed Oxidative Cleavage of Lignin β-O-4 Model Compounds under Mild Conditions,ACS Sustainable Chemistry & Engineering

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Nitrogen-Doped Carbon-Modified Cobalt-Nanoparticle-Catalyzed Oxidative Cleavage of Lignin β-O-4 Model Compounds under Mild Conditions
ACS Sustainable Chemistry & Engineering ( IF 7.1 ) Pub Date : 2018-09-10 00:00:00 , DOI: 10.1021/acssuschemeng.8b02802
Huihui Luo _{1,

2} , Lianyue Wang ₂ , Guosong Li ₂ , Sensen Shang ₂ , Ying Lv ₂ , Jingyang Niu ₁ , Shuang Gao ₂

Affiliation

A noble-metal-free Co-based catalyst, derived from pyrolysis of natural vitamin B₁₂ on activated carbon, is developed for the first time for one-pot oxidative cleavage of lignin linkages to phenols and aromatic esters with molecular oxygen as the oxidant under mild reaction conditions. High yields of phenol were obtained, and no oxidative coupling of phenol was produced based on the present cobalt catalyst. Compared to the previous report, the present catalyst can achieve the oxidative cleavage of β-O-4 ketones even at room temperature using a dioxygen balloon. The heterogeneous catalyst shows robust recyclability and can be conveniently recovered and reused up to eight times without an appreciable loss of catalytic activity. Moreover, this catalyst system can realize the bond cleavage of organosolv lignin. The evidence of depolymerization was given by two-dimensional heteronuclear single quantum coherence NMR and gel permeation chromatography. Characterization of the catalyst by inductively coupled plasma, N₂ adsorption–desorption, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, high-angle angular dark-field scanning TEM, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and control experiments provide a fundamental understanding of the catalytic materials and the reaction pathway. Co₃O₄ in situ supported on a N-doped carbon matrix by the way of high-temperature pyrolysis might be a catalytically active species. Two reaction intermediates are detected and confirmed by gas chromatograph–mass spectrometry.

中文翻译：

轻度条件下氮掺杂碳修饰的钴-纳米颗粒催化木质素β-O-4模型化合物的氧化裂解

天然维生素B _12的热解衍生的无贵金属的钴基催化剂首次在活性炭上开发了一种在温和的反应条件下用分子氧作为氧化剂将木质素键与酚和芳香族酯进行单锅氧化裂解的方法。基于本发明的钴催化剂，获得了高产率的苯酚，并且没有产生苯酚的氧化偶联。与先前的报告相比，本发明的催化剂即使在室温下使用双氧气球也可以实现β-O-4酮的氧化裂解。该非均相催化剂显示出强大的可回收性，可以方便地回收和重复使用多达八次，而不会明显降低催化活性。而且，该催化剂体系可以实现有机溶剂木质素的键裂解。二维异核单量子相干核磁共振和凝胶渗透色谱法给出了解聚的证据。通过电感耦合等离子体N表征催化剂₂吸附-解吸，拉曼光谱，扫描电子显微镜，透射电子显微镜（TEM），高分辨率TEM，大角度暗场扫描TEM，能量分散X射线光谱，X射线光电子光谱和控制实验提供了对催化材料和反应途径的基本了解。通过高温热解原位负载在N掺杂碳基体上的Co ₃ O ₄可能是催化活性物质。气相色谱-质谱法检测并确认了两种反应中间体。

更新日期：2018-09-10

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