The interaction of 5-Hydroxymethyl Furfural (HMF) on a biochar catalyst after the addition of an oxidant and co-catalyst - MAPS

The oxidation of 5-hydroxymethyl furfural (HMF) can lead to the production of poly(ethylene 2,5-furandicarboxylate) (PEF) – a polymer that could replace the petroleum based polyethylene terephthalate (PET). In this context, we have developed a naturally iron-containing biochar (BCR) catalyst from palm oil empty fruit bunch which we found to catalyse the reaction under very mild conditions by use of an organic peroxide and radical mediator co-catalyst. We have recently probed the mechanism of the catalysis to understand the molecular-scale interaction of the HMF with the BCR using INS and results show that the C-H and O-H of bending modes of HMF are observed differently when the radical initiator TEMPO as the co-catalyst was added. We now wish to probe the mechanism of the catalysis when both the co-catalyst and the oxidant are added. For HMF oxidation such mechanistic detail is missing in the literature and for our material such information will allow us to improve and optimise the catalyst further. BCR is very difficult to study by conventional vibrational spectroscopy, as the infrared spectrum is dominated by the residual oxygen functionalities and the Raman by carbon modes. INS enables the complete spectral range to be examined, and parallel proposals for MAPS (for the region above 2500 cm-1) and TOSCA (for the region below 2500 cm-1) will be submitted.

5-羟甲基糠醛（5-hydroxymethyl furfural, HMF）的氧化反应可用于制备聚（2,5-呋喃二甲酸乙二醇酯）（poly(ethylene 2,5-furandicarboxylate), PEF）——一种可替代石油基聚对苯二甲酸乙二醇酯（PET）的高分子材料。在此背景下，我们以棕榈油空果串为原料制备了天然含铁生物炭（BCR）催化剂，发现其可在极温和的反应条件下，借助有机过氧化物与自由基介导型助催化剂催化该氧化反应。近期我们借助非弹性中子散射（Inelastic Neutron Scattering, INS）探究了该催化反应的机理，以解析HMF与BCR之间的分子尺度相互作用，研究结果显示：当添加作为助催化剂的自由基引发剂TEMPO时，HMF的C-H与O-H弯曲振动模式的响应存在显著差异。本次研究我们希望进一步探究同时添加助催化剂与氧化剂时的催化反应机理。目前公开文献中尚未有针对HMF氧化反应的此类机理细节研究，而针对我们研发的BCR催化剂而言，此类信息将助力我们进一步优化与改良该催化体系。常规振动光谱法难以对BCR进行有效表征：其红外光谱会被残留的含氧官能团主导，拉曼光谱则受碳骨架振动模式干扰，而INS可覆盖完整的光谱探测范围。因此我们将分别提交针对2500 cm⁻¹以上波段的MAPS谱仪申请，以及针对2500 cm⁻¹以下波段的TOSCA谱仪申请。