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Synergy of electronic and steric effects of Br-Ni catalysts for selective hydrogenolysis of diphenyl ether to phenol
Chemical Engineering Journal ( IF 13.3 ) Pub Date : 2023-09-18 , DOI: 10.1016/j.cej.2023.146144
Xiaomeng Yang , Zhen Zhang , Puhua Shao , Armin Rezayan , Dan Wu , Chunbao Charles Xu , Jianshe Wang , Yongsheng Zhang

Selective hydrogenolysis of 4-O-5 bond in lignin under relatively mild conditions is an important strategy for the production of valuable aromatic products, e.g. phenols, from renewable carbon resources. However, the easy saturation of benzene rings under reductive conditions over metal catalyst reduces the selectivity to aromatics. In this work, we investigated the effect of bromination of supported Ni nanoparticles on the phenol selectivity during the hydrogenolysis of diphenyl ether (DPE), a commonly used lignin model compound. Compared with the unmodified catalysts, Br-Ni/Al2O3 catalyst derived from Ni-Al layered double oxides exhibits enhanced phenol selectivity (37% vs. 15%) under similar DPE conversions (60%). Various characterizations including transmission electron microscopy (TEM), in-situ X-ray photoelectron spectroscopy (XPS), extended X-ray absorption fine structure (EXAFS), and CO-Fourier transform infrared spectroscopy (FTIR) indicate that Br preferentially located at the terrace site of Ni nanoparticles, deactivating the continuous Ni sites for benzene ring hydrogenation. In addition, the electron-withdrawing effect of Br creates positively charged Ni sites at the corners, facilitating the hydrogenolysis of C–O aryl ether bonds. During the hydrogenation of real lignin, the selective poisoning and electronic effects introduced by Br synergistically increased the yield of phenols from 12.20% on the initial Ni/Al2O3 to 30.47% over the Br-Ni/Al2O3 catalyst. This work provides an advanced strategy for the catalytic valorization of lignin by halogen modified metal-based catalysts.



中文翻译:

Br-Ni催化剂的电子和空间效应协同二苯醚选择性氢解制苯酚

在相对温和的条件下选择性氢解木质素中的4-O-5键是从可再生碳资源生产有价值的芳香族产品(例如酚)的重要策略。然而,苯环在金属催化剂的还原条件下容易饱和,降低了对芳烃的选择性。在这项工作中,我们研究了负载型镍纳米粒子的溴化对二苯醚(DPE)(一种常用的木质素模型化合物)氢解过程中苯酚选择性的影响。与未改性催化剂相比,Br-Ni/Al 2 O 3由 Ni-Al 层状双氧化物衍生的催化剂在相似的 DPE 转化率 (60%) 下表现出更高的苯酚选择性 (37% vs. 15%)。各种表征,包括透射电子显微镜 (TEM)、原位X射线光电子能谱(XPS)、扩展X射线吸收精细结构(EXAFS)和CO-傅里叶变换红外光谱(FTIR)表明Br优先位于Ni纳米颗粒的平台位点,使苯的连续Ni位点失活环氢化。此外,Br的吸电子效应在角部产生带正电的Ni位点,促进C-O芳基醚键的氢解。在真实木质素加氢过程中,Br引入的选择性中毒和电子效应协同地将酚的产率从初始Ni/Al 2 O 3的12.20%提高到Br-Ni/Al 2 O 3的30.47%催化剂。这项工作为卤素改性金属基催化剂催化木质素增值提供了一种先进的策略。

更新日期:2023-09-18
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