Abstract:

N₂O is an important greenhouse gas with significant destructive effect on ozone layer. Direct catalytic decomposition is one of the most cost-effective ways to remove N₂O. In recent years, plenty of researches on direct catalytic decomposition of N₂O have been focusing on supported cobalt oxide catalysts due to their excellent low-temperature catalytic performance. An encapsulated cobalt-based core-shell material was first introduced into the N₂O direct catalytic decomposition reaction. The dimension-limited core structure and mesoporous shell structure could effectively improve the metal dispersion, reduce particle size, and increase contact interface between active metal oxide and reactants, so that low temperature catalytic activity was significantly enhanced in N₂O catalytic decomposition. Furthermore, a series of Co₃O₄@SiO₂ spherical core-shell catalysts with different metal content were prepared to investigate the effect of encapsulation structure on catalytic performance. Characterizations on catalysts with techniques such as X-ray fluorescence spectroscopy (XRF), high-resolution transmission electron microscopy (HR-TEM), X-ray diffraction (XRD), N₂ adsorption-desorption and hydrogen temperature-programmed reduction (H₂-TPR) indicated that catalysts with more active Co sites have better activity under premise of stable monodisperse core-shell structure.

Key words: greenhouse gas emission, N₂O direct catalytic decomposition, nanomaterial, Co₃O₄@SiO₂, core-shell catalyst

摘要：

N₂O是一种重要的温室气体，且对臭氧层有很大的破坏作用，而直接催化分解法是除去N₂O最经济有效的方法之一。针对目前报道较多的钴氧化物催化剂活性较差的问题，将包覆型Co₃O₄核壳材料引入N₂O直接催化分解反应，利用核壳结构的限域特性与壳层的多孔孔道使Co₃O₄分散性增加，粒径减小，金属载体相互作用与接触反应界面增强，从而提高了催化剂在N₂O直接催化分解反应中的低温活性。此外，还制备了一系列不同金属含量的Co₃O₄@SiO₂球形核壳催化剂来研究包覆结构对催化剂性能的影响，通过X射线荧光光谱（XRF）、透射电镜（TEM）、X射线衍射（XRD）、N₂物理吸附、H₂-程序升温还原（H₂-TPR）等表征，证实在保证稳定单分散核壳结构的前提下，活性Co₃O₄位点越多，催化剂反应活性越好。

关键词: 温室气体减排, N₂O直接催化分解, 纳米材料, Co₃O₄@SiO₂, 核壳催化剂