| 摘要:为了解决氨燃料发动机的氧化亚氮（N2O）排放问题，研究一种Ni、Mg掺杂的钴尖晶石催化剂用于N2O高效分解。采用共沉淀法合成一系列过渡金属M（Cu、Ni、Mg）掺杂钴尖晶石（Co3O4）形成MxCo3-xO4复合金属氧化物，并探究其在不同气氛下的催化活性。Ni0.4Mg0.2Co2.4O4催化剂可在350 ℃时达到90%的N2O分解效率，在通有10%水蒸气反应的情况下480 ℃完全转化。通过一系列表征手段发现：Ni、Mg同时掺杂进入晶格结构较好，形成较为完整的整体尖晶石结构；Ni、Mg协同Co作为活性位点，使钴尖晶石分散度更好，并未像Cu等掺杂时形成对应金属氧化物的杂相而减少活性中心是其改性效果进一步提升的重要原因；同时因Ni、Mg同时掺杂进入晶格，使掺杂后钴尖晶石晶格膨胀，晶格尺寸变大，比表面积有明显提升，高于Ni、Mg单独掺杂，增加了接触活性位点，使其拥有更低的反应温度；通过XPS发现Ni0.4Mg0.2Co2.4O4中Co2+、Ni2+的结合能均最高，电子云密度相对最低，有助于N、O中的电子向其转移，且作为主要分解活性中心的Co2+占比最高，从能量和价态角度解释了其同温度下分解效率最高的现象；此外，在H2-TPR下，随着Ni、Mg掺杂量的增加，H2的还原温度更高，说明其在高低温下的还原性更强，有助于对N2O中的高价N进行吸附还原，而Ni0.4Mg0.2Co2.4O4在60 h时的60 000 h-1空速气流下也显示出较好的稳定性（350 ℃下转化率维持在90%左右）。 |
| 关键词: 氨燃料 氧化亚氮 钴尖晶石 Ni掺杂催化剂 催化分解 复合金属氧化物 |
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| Catalytic Decomposition of N2O Using Cobalt Spinel Catalyst Doped with Ni and Mg |
| HU Nan,ZHAO Xuteng,ZHANG Yiran,CHEN Ting,LIN He |
| School of Mechanical Engineering， Shanghai Jiao Tong University， Shanghai 200240， China |
| Abstract:Research was conducted on a cobalt spinel catalyst doped with Ni and Mg for the efficient decomposition of nitrous oxide（N2O），to address the issue of N2O emissions from ammonia-fueled engines.Series of transition metal M（Cu，Ni，Mg）doped cobalt spinels（Co3O4）were synthesized by the co-precipitation method to form composite metal oxides MxCo3-xO4，and their catalytic activities under different atmospheres were investigated.The Ni0.4Mg0.2Co2.4O4 catalyst could achieve a 90% decomposition efficiency of N2O at 350 ℃，and complete conversion is achieved at 480 ℃ under the reaction with 10% steam. A series of characterization methods revealed that：The simultaneous doping of Ni and Mg into the lattice structure was well integrated，forming a more complete overall spinel structure；The synergistic effect of Ni and Mg，along with Co as active sites，resulted in better dispersion of the cobalt spinel，and unlike doping with Cu and other elements that formed corresponding metal oxide impurities，reduced the number of active centers，which was an important reason for the further improvement of its modification effect；Due to the simultaneous doping of Ni and Mg into the lattice，the doped cobalt spinel experienced lattice expansion and increasing of lattice dimensions，resulting in a significant enhancement of the specific surface area，which was higher than that of individual doping with Ni or Mg，thus increased the number of active sites for contact，enabling it to have a lower reaction temperature；XPS analysis revealed that in Ni0.4Mg0.2Co2.4O4，Co2+ and Ni2+ had the highest binding energy，and the density of electron cloud is the lowest，which facilitated the transfer of electrons from N and O to them；The proportion of Co2+，as the main decomposition active center，was the highest，which explained the phenomenon of its highest decomposition efficiency at the same temperature from the perspectives of energy and valence state；Under H2-TPR conditions，as the doping amounts of Ni and Mg increase，the reduction temperature of H2 was higher，indicating stronger reducibility at both high and low temperatures，which was beneficial for the adsorption and reduction of the high-valent N in N2O；Ni0.4Mg0.2Co2.4O4 also showed good stability under a 60 000 h-1 air flow at 60 h（maintaining a conversion rate of around 90% at 350 ℃）. |
| Key words: ammonia fuel nitrous oxide cobalt spinel Ni-doped catalyst catalytic decomposition composite metal oxide |
