复旦大学龚鸣团队报道了定向离子交换的超密集负载氧化钌簇对5-羟甲基糠醛的有效增值。相关研究成果发表在2024年3月30日出版的国际知名学术期刊《德国应用化学》。

最大限度地增加活性中心的负载量而不聚集负载的催化剂是一个巨大的挑战，但对于实现高重量活性，特别是对于多步反应而言，这是至关重要的。5-羟甲基糠醛（HMF）是一种关键的生物质衍生平台分子，其氧化为2,5-呋喃二羧酸（FDCA）是聚酯单体的一种很有前途的替代品，这是一个涉及6个电子转移的多步骤反应。

该文中，研究人员设计了一种在钴羟基阴离子（CoHA）载体上产生超致密负载氧化钌团簇的策略。嘧啶配体首先被嵌入CoHA夹层中，随后它们的离开产生了用于与CoHA中内置阴离子进行定向离子交换的多孔通道，这使许RuCl₆^2-阴离子及其产生的Ru氧化物团簇的致密和单分散功能化。

这些超致密氧化钌团簇不仅能够在中性条件下实现高HMF电氧化电流，而且还在团簇之间产生微观通道，用于加速中间体向高度氧化的产物（如5-甲酰基-2-糠酸（FFCA）和FDCA）的再吸附和氧化。最终开发了一种两阶段HMF氧化工艺，包括在60℃下将HMF转化为FFCA和将FFCA氧化为FDCA，以首先实现92.1%的高FDCA产率和显著减少的聚合。

附：英文原文

Title: Ultra-Dense Supported Ruthenium Oxide Clusters via Directed Ion Exchange for Efficient Valorization of 5-Hydroxymethylfurfural

Author: Can Lei, Zhe Chen, Tao Jiang, Shaoyan Wang, Wei Du, Shuangshuang Cha, Yaming Hao, Ran Wang, Xueting Cao, Ming Gong

Issue&Volume: 2024-03-30

Abstract: Maximizing the loading of active centers without aggregation for a supported catalyst is a grand challenge but essential for achieving high gravimetric activity, especially toward multi-step reactions. The oxidation of 5-hydroxymethylfurfural (HMF), a key biomass-derived platform molecule, into 2,5-furandicarboxylic acid (FDCA), a promising alternative to polyester monomer, is such a multi-step reaction that involves 6 electron transfers. Herein, we devised a strategy of creating ultra-dense supported Ru oxide clusters on a Co hydroxyanion (CoHA) support. Pyrimidine ligands were first incorporated into the CoHA interlayers, and their subsequent evacuation created porous channels for the directed ion exchange with the built-in anions in CoHA, which allows the dense and mono-disperse functionalization of RuCl62- anions and their resulting Ru oxide clusters. These ultra-dense Ru oxide clusters not only enable high HMF electrooxidation currents under neutral conditions but also create microscopic channels in-between the clusters for the expedited re-adsorption and oxidation of intermediates toward highly oxidized product, such as 5-formyl-2-furoic acid (FFCA) and FDCA. A two-stage HMF oxidation process, consisting of ambient conversion of HMF into FFCA and FFCA oxidation into FDCA under 60 oC, was eventually developed to first achieve a high FDCA yield of 92.1% with significantly reduced polymerization.

DOI: 10.1002/anie.202319642

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202319642