核壳结构Co_(3)O_(4)@MnOx整体式催化剂的碳烟催化燃烧性能

Catalytic soot combustion performance of core-shell Co_(3)O_(4)@MnOx monolithic catalyst

采用两步水热法在泡沫镍基底上合成了具有纳米棒形貌的Co_(3)O_(4)@MnOx整体式催化剂,通过X射线衍射、X射线能谱分析、氢气-程序升温还原、X射线光电子能谱、拉曼光谱和碳烟-程序升温还原等手段对催化剂进行表征,在微型固定床反应器上评价了其催化碳烟燃烧性能,通过等温动力学实验探究了催化剂的本征活性。结果表明,Co_(3)O_(4)@MnOx催化剂呈现了以Co_(3)O_(4)为核、以MnOx为壳的核壳结构。与催化剂Co-NW相比,Co_(3)O_(4)@MnOx催化剂中Co_(3)O_(4)与MnOx之间的相互作用使其表面产生了更多高价物种Mn^(4+)和Mn^(3+)以及更多的表面氧空位,其氧化还原性能提高,催化剂的活性氧物种数量增加了两倍,催化性能得到改善,在NO存在的反应气氛中使碳烟起燃温度降低148℃。此外,相比催化剂CoNW,Co_(3)O_(4)@MnOx催化剂使碳烟燃烧反应的活化能从113.6 kJ/mol降低至102.2 kJ/mol,催化剂的本征活性提高了两倍。

The Co_(3)O_(4)@MnOx monolithic catalyst with nanorod morphology was synthesized on nickel foam by a two-step hydrothermal process and characterized by XRD,EDS-mapping,H2-TPR,XPS,Raman and Soot-TPR.The catalytic soot combustion activities of the catalysts were investigated in a fixed-bed micro-reactor and the intrinsic activities of the catalysts were investigated by the isothermal kinetic experiments.The results reveal that the Co_(3)O_(4)@MnOx catalyst shows a core-shell structure with Co_(3)O_(4) as the core and MnOx as the shell.Compared with Co-NW,there exist more high-valent state species of Mn^(4+)and Mn^(3+)and oxygen vacancies on the Co_(3)O_(4)@MnOx catalyst surface due to the interaction between Co_(3)O_(4) and MnOx,which improve the redox performance of Co_(3)O_(4)@MnOx.Compared with Co-NW,the active oxygen species amount of Co_(3)O_(4)@MnOx is increased by two times,and Co_(3)O_(4)@MnOx shows enhanced activity,which lowers the ignition temperature by 148℃in the presence of NO.Also,compared with Co-NW,Co_(3)O_(4)@MnOx decreases the activation energy of soot combustion reaction from 113.6 to 102.2 kJ/mol,and its intrinsic activity is increased by two times.