The conversion of macromolecular saccharides (fructose, glucose, sucrose, and inulin) to 5-hydroxymethylfurfural (HMF) is often limited by the mass transfer resistance of existing catalysts. Herein, a two-dimensional metal–organic framework (NUS-8-PhSO₃H) containing high densities of dual acidic sites (Lewis and Brønsted acid sites) was developed for the first time by diazo grafting. Characterization results and reaction kinetics showed that the rapid molecular diffusion leads to an unusual pseudozeroth reaction order and a considerably lower apparent activation energy for the fructose reaction over NUS-8-PhSO₃H in contrast to the first order and higher activation energy over three-dimensional counterpart (NUS-16-PhSO₃H) and reported catalysts. In addition, NUS-8-PhSO₃H can also produce substantially high HMF yields and has a low activation energy for other saccharides (glucose, sucrose, and inulin) by powerful tandem steps, including polysaccharide hydrolysis, glucose isomerization, and fructose dehydration. The preparation of hydrophobic acidic NUS-8-PhSO₃H provides an efficient means of synthesizing HMF from various saccharides.

中文翻译：

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具有双酸性位点的二维金属有机骨架，用于将糖类稳定化为 5-羟甲基糠醛

大分子糖类（果糖、葡萄糖、蔗糖和菊粉）向 5-羟甲基糠醛 (HMF) 的转化通常受到现有催化剂的传质阻力的限制。在此，首次通过重氮接枝开发了含有高密度双酸位点（Lewis 和 Brønsted 酸位点）的二维金属有机骨架 (NUS-8-PhSO _{3 H)。表征结果和反应动力学表明，快速分子扩散导致不寻常的伪零级反应阶数和果糖反应在 NUS-8-PhSO 3} H 上的明显较低的表观活化能，这与三级反应的一级反应和较高的活化能形成对比。三维对应物（NUS-16-PhSO ₃H) 和报道的催化剂。此外，NUS-8-PhSO ₃ H 还可以通过强大的串联步骤（包括多糖水解、葡萄糖异构化和果糖脱水）产生非常高的 HMF 产率并且对其他糖类（葡萄糖、蔗糖和菊粉）具有低活化能。疏水酸性NUS-8-PhSO ₃ H的制备提供了从各种糖类合成HMF的有效手段。