The reaction steps involved in the 5‐hydroxymethylfurfural to 2,5‐furandicarboxylic acid conversion by means of H2O2 were investigated employing a dedicated computational protocol based on density functional theory. The catalytic environment of choice was a molecular model representing a portion of the halloysite nanotube outer surface, functionalized by an organosilane, the 3‐aminopropyltriethoxysilane, whose amino group bonds one gold atom. At this stage of the investigation, the process was wholly detailed in terms of the interactions between the reaction intermediates and the catalyst, and the reaction standard free energies. In addition, the energy barriers of the elementary steps involving the hydrogen migration from the adsorbed organic species to the gold atom were analyzed. On the basis of the interaction geometries, a certain distinction among the preferred reaction path can be inferred as a function of the net negative charge characterizing the catalyst outer surface. Since the inner surface of halloysite can represent the acid environment needed to obtain 5‐hydroxymethylfurfural through dehydration of fructose, the present study is framed in a wider research field where the possibility to consider functionalized halloysite as one‐pot reactor for the valorization of biomass is explored.

中文翻译：

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改性埃洛石作为羟甲基糠醛转化为呋喃二甲酸的催化剂：DFT 研究

采用基于密度泛函理论的专用计算方案研究了通过 H2O2 将 5-羟​​甲基糠醛转化为 2,5-呋喃二甲酸的反应步骤。选择的催化环境是代表埃洛石纳米管外表面一部分的分子模型，由有机硅烷（3-氨基丙基三乙氧基硅烷）功能化，其氨基键合一个金原子。在研究的这个阶段，该过程在反应中间体和催化剂之间的相互作用以及反应标准自由能方面得到了全面详细的描述。此外，还分析了氢从吸附的有机物质迁移到金原子的基本步骤的能垒。基于相互作用的几何形状，可以将优选反应路径之间的某种区别推断为表征催化剂外表面的净负电荷的函数。由于埃洛石的内表面可以代表通过果糖脱水获得5-羟甲基糠醛所需的酸性环境，因此本研究处于更广泛的研究领域，其中将功能化埃洛石视为生物质增值的一锅反应器的可能性是探索过。