Cu基复合纳米材料的可控制备及催化糠醛转化研究

Oxidation of furfural to maleic acid and maleic anhydride is one of the key steps of furfural upgrading. However, the currently utilized heterogeneous metal-based catalysts suffer from low reactivity, low selectivity and deactivation, of which the fundamental reason is that it is difficult to regulate the physicochemical properties of both metal species and supports in the preparation process. In this project, we will employ the molten salts, which process good electrical conductivity, thermal conductivity and polarity, to regulate the pyrolysis process of the Cu-based metal organic frameworks (MOFs), aiming to prepare the composite nanoscale catalyst with Cu nanoparticles with small sizes, specific morphology and crystal facet and carbon supports with certain topography and pore structures. In theory, this study will reveal the effects of MOFs templates, molten salts and pyrolysis programs on the above-mentioned properties of the obtained Cu-based nanomaterials. Meanwhile, this project will also establish the structure-performance relationship of Cu-based catalysts and elucidate the reaction mechanisms of furfural oxidation to maleic acid and maleic anhydride. In technology, a general strategy utilizing molten salt to regulate the pyrolysis of MOFs will be developed to provide the highly efficient catalysts for the green upgrading of furfural. This project is of important theoretical and practical significance.

糠醛氧化制备马来酸和马来酸酐是其高值化利用的重要步骤之一，但目前此过程所使用的非均相金属催化剂普遍存在活性和选择性较低、易失活等问题，根本原因在于制备过程中难以同时调控金属和载体两组分的物理化学性质。本项目拟利用具有优良导电性、导热性和极性的熔融盐调控Cu基金属有机骨架(MOFs)的热解过程，以期制备具有细小尺寸、特殊形貌、晶型的Cu纳米颗粒和一定形貌、孔结构的碳载体的复合纳米催化剂。在理论层面上，揭示MOFs和熔融盐种类、热解程序等条件对所得Cu基纳米材料以上性质的影响规律；建立Cu基纳米材料结构与催化性能之间的定性或定量关系；阐明Cu基催化剂上糠醛氧化制备马来酸和马来酸酐的反应机理。在技术层面上，开发出利用熔融盐调控MOFs热解的通用策略，为糠醛的绿色高值化利用提供高效催化剂。本项目具有重要的理论和实际意义。

本项目从糠醛高值化利用的实际需求出发，聚焦糠醛氧化制备马来酸和马来酸酐过程中催化剂活性、选择性和稳定性等关键问题，研制新型熔融盐介导的Cu基金属有机骨架(MOF)热解制备技术，以期制备高性能催化剂。项目进行期间，成功开发出通用、高效的熔融盐辅助热解制备技术及理论，在MOF热解过程中同时调控金属和碳组分的理化性质，制得负载在微孔-介孔-大孔多级结构碳载体中的原子级催化剂。通过控制实验和理论计算归纳并验证了相关机制，总结出一般规律。所得Cu基双金属催化剂应用于糠醛氧化反应，在最优条件下成功实现了几乎定量制备马来酸，催化活性是目前文献报道最优结果的20倍以上，循环利用六次无衰减。进一步地，通过控制实验和理论计算，揭示了糠醛分子的转化过程和反应机理。本项目的相关成果，可望为研制高性能Cu基纳米催化剂提供新思路。