Herein, we report a controllable and versatile strategy for the synthesis of highly dispersed Co nanoparticles embedded in open-channel hierarchically porous N/O-doped carbon skeleton. Moreover, the pore sizes of the hierarchical structures can be easily tuned by adjusting the size of precursors. The as-obtained Co@NC-2ST exhibits unprecedented activity and selectivity in the oxidative esterification of 5-hydroxymethylfurfural (HMF) to dimethyl furan-2,5-dicarboxylate under base-free and atmospheric conditions. In particular, the achieved turnover frequency value is an order of magnitude higher than that of the state-of-art heterogeneous catalysts reported to date. A combination of experimental and density function theory studies reveals that the unique features of Co@NC-2ST enable a novel reaction route, that is, the CHO group of HMF is preferentially esterified instead of the OH group. This can be attributed to the nucleophilic addition reaction caused by the attack of methoxy anion on the CHO group of HMF.

中文翻译：

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分级多孔碳限制的钴纳米颗粒用于 5-羟甲基糠醛的高效氧化酯化


在此，我们报告了一种可控且通用的策略，用于合成嵌入开放通道分层多孔 N/O 掺杂碳骨架中的高度分散的 Co 纳米颗粒。此外，通过调整前驱体的尺寸可以轻松调节分级结构的孔径。所获得的Co@NC-2ST在无碱和大气条件下，在5-羟甲基糠醛（HMF）氧化酯化为2,5-二甲酸二甲酯呋喃方面表现出前所未有的活性和选择性。特别是，所实现的周转频率值比迄今为止报道的最先进的多相催化剂高一个数量级。实验和密度函数理论研究相结合表明，Co@NC-2ST的独特特征实现了一种新颖的反应路线，即HMF的 CHO基团优先被酯化而不是 OH基团。这可以归因于甲氧基阴离子攻击HMF的-CHO基团引起的亲核加成反应。