介孔MnOx-Co3O4催化剂的“软机械化学法”合成及催化氧化性能研究

The mesoporous metal oxides have the superior catalytic performances. However, their conventionally liquid-phase preparation route often have some disadvantages, such as tedious multistep processing and the need for delicate temperature control, as well as the formation of vast amount of environmental wastes. Herein, a variety of novel mesoporous cobalt-based mixed metal oxides are synthesized via a facile soft mechanochemical solid-state-reaction route, using surfactants or amino acids as the soft template. The work aims to get further insights into the catalytic properties of such cobalt oxide based catalysts for preferential oxidation of CO in hydrogen and total oxidation of air pollutants(CO, C3H8), which have drawn great attention due to their wide application and acedemic studies in the catalysis field. And then, an efficient non-noble metal catalyst will be developed to provide a new approach for selective oxidation and total oxidation. Meanwhile, combined with modern in-situ characterization techniques, the structure of the catalysts such as the mesoporous structure, morphology characteristics, surface composition, particle size, crystal cell parameters, the synergy effect between metals and so on, will be studied extensively. Our study may also have implications in the fundamental understanding of the activation process of oxygen and the nature for catalytic oxidation.

大比表面积、高孔隙率的介孔金属氧化物具有独特的催化性能,但传统湿法合成技术能耗高、时间长、环境污染严重、工艺复杂。本项目拟采用“软机械化学法”低温固相合成，以表面活性剂、氨基酸等为软模板，方便、快捷、高效环保合成一系列具有新颖介孔结构的钴基金属复合氧化物催化剂(MnOx-Co3O4)。针对具有重要应用前景的反应体系（富氢气氛下CO选择氧化；CO、C3H8等大气污染物的完全氧化），考察所制备催化剂的活性和选择性，为选择氧化和完全氧化提供新途径。同时结合多种现代原位表征手段，对催化剂的介孔结构、形貌特点、表面组成、粒径大小、晶胞参数、金属间的协同作用进行深入研究，从而在理论上进一步探究分子氧的活化过程及催化剂的催化氧化本质。

介孔过渡金属氧化物因具有大比表面积、高孔隙率等优点，其合成与应用成为催化材料领域的研究焦点之一。针对传统湿化学法合成技术的步骤繁琐、时间长、环境污染严重等问题，本项目利用“软机械化学法”低温固相合成技术，以碱式碳酸盐和配体酸为反应原料，利用酸碱反应机理进行活化，便捷高效合成了一系列介孔钴基金属氧化物，并采用多种表征手段对催化剂的结构进行了表征，进一步用于富氢气氛下CO选择氧化及大气污染物（CO，C3H8等）的完全氧化研究。研究发现适量的锰修饰四氧化三钴后，会降低催化剂的粒径，提高比表面，产生晶胞畸变，尤其是提高催化剂表面活性氧物种的含量，从而提高催化剂在富氢气氛下CO选择氧化和CO低温氧化领域的活性和稳定性。研究表明各种表面活性剂的适量修饰，则可以显著改善催化剂的介孔结构及比表面积等物化性质，从而改进催化剂的催化氧化性能。本项目拓展了固相合成化学法的应用范围，为合成新颖介孔结构的高活性金属氧化物材料提供了一种新途径，并为深度探索催化氧化反应的本质提供了理论依据。