重稀土复合氧化物多孔板状催化剂用于氨氧化制硝酸的研究 Ⅰ.板状催化剂的反应性能

STUDIES ON POROUS PLATE CATALYST CONTAINING MIXED OXIDES OF HEAVIER RARE EARTH AND COBALT FOR AMMONIA OXIDATION Ⅰ. REACTION PERFORMANCE OF PLATE CATALYST

制备了用于氨氧化制硝酸的含重稀土和钴的复合氧化物催化剂。研究了几种不同的载体和它们的几何形状对催化剂活性的影响。测定了板状催化剂的传质因素。用X射线电子能谱、热重分析等方法比较了复合氧化物和Co_3O_4催化剂的反应稳定性。结果表明,用α-Al_2O_3载体制备的多孔板状催化剂与粒状和蜂窝状催化剂相比具有比表面积大,表面反应性能好等特点。复合氧化物催化剂较Co_3O_4催化剂具有更好的反应稳定性,其原因主要是复合氧化物具有稳定的晶相结构和Co^(3+)活性中心离子。

Catalysts containing mixed oxides of heavier rare earth and cobalt for the production of HNO3 through ammonia oxidation have been prepared. The influence of carriers and their geometry on the catalytic activity of the catalyst was studied. The effect of reaction temperature and space velocity on activity was also determined. In addition, the stability of the mixed oxides catalyst was studied by XPS and thermogravimetric analysis. The efficiency of mass transfer of the porous plate catalyst was investigated by determining the factor of mass transfer. The results showed that the porous plate catalyst supported on α-Al2O3 had a larger specific surface area and better performance for surface reaction than the pellet and honeycomb catalysts. The porous plate catalyst showed a larger external surface area, a lower catalyst bed height and a smaller resistance to gas than the pellet catalyst.Compared with the Co3O4 catalyst, the mixed oxides catalyst had better thermal stability clue to its stable crystal structure and active center ion Co3 + .