Abstract:

Nitrous oxide (N₂O) is the third greenhouse gas in amount, after carbon dioxide (CO₂) and methane (CH₄), and has extremely harmful impact on environment. A series of Ag-doped cobalt based transition metal oxide catalysts (3.0F-Ag _x Co, x=0—0.1) were prepared by the sol-gel method using the surfactant F127 as the complexing agent and used for direct catalytic decomposition of N₂O. It was observed that Ag was highly dispersed on the catalyst surface in the form of Ag₂O. In comparison to 3.0F-Co₃O₄, the incorporation of Ag resulted in a reduction of the average grain size of Co₃O₄ and a weakening of the Co—O bond, which significantly enhanced the low-temperature activity of the catalyst. Meanwhile, the weakening of the Co—O bond facilitated the regeneration of oxygen vacancies on the catalyst surface, resulting in a lower reaction activation energy and a higher specific reaction rate. Furthermore, the 3.0F-Ag_0.02Co catalyst displayed high catalytic activity and stability under 5% O₂, 100μL/L NO and 2% H₂O, maintaining a N₂O conversion of 85% for 15h at 400℃.

Key words: catalytic N₂O decomposition, catalyst, surfactants, silver, tricobalt tetraoxide

摘要：

N₂O作为继CO₂和CH₄后的第三大温室气体，对大气环境危害极大。本文以表面活性剂F127为络合剂，采用溶胶-凝胶法制备了一系列Ag掺杂的钴基过渡金属氧化物催化剂3.0F-Ag _x Co（x=0～0.1），并用于直接催化分解N₂O的研究。研究发现，与3.0F-Co₃O₄相比，Ag以Ag₂O的形式高度分散在催化剂表面。助剂Ag的加入减小了Co₃O₄的平均晶粒尺寸，削弱了Co—O键，从而显著增强了催化剂的低温活性。同时，由于Co—O键的削弱促进了催化剂表面氧空位的再生，使得3.0F-Ag_0.02Co催化剂在反应中的活化能降低，并表现出更高的比反应速率。此外，3.0F-Ag_0.02Co催化剂在5%（体积分数）O₂ + 100μL/L NO + 2%（体积分数）H₂O的共同影响下依然具有较高的催化活性和稳定性，在15h以上的稳定性测试中，400℃时仍能维持85%的N₂O转化率。

关键词: 催化分解N₂O, 催化剂, 表面活性剂, 银, 四氧化三钴