Low-Temperature Oxidation of CO Catalyzed by Co3O4 Nanorods.
Low-Temperature Oxidation of CO Catalyzed by Co3O4 Nanorods.
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DOI：
10.1002/chin.200927013
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发表时间：
2009-07
期刊：
影响因子：
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通讯作者：
Xiaowei Xie;Yong Li;Zhiqi Liu;M. Haruta;Wenjie Shen
中科院分区：
文献类型：
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作者：
Xiaowei Xie;Yong Li;Zhiqi Liu;M. Haruta;Wenjie Shen
CO的低温氧化可能是多相催化史上研究最广泛的反应，在清洁空气和降低汽车排放方面变得越来越重要。Hopcalite催化剂（锰和铜氧化物的混合物）最初是为净化潜艇中的空气而开发的，但它们在环境温度下不是特别活跃，而且在潮湿的情况下也会失效。另一方面，贵金属催化剂耐水，但通常需要100°C以上的温度才能有效运行。金在低温下表现出高活性，在潮湿条件下表现出优异的稳定性，但只有当金以纳米颗粒的形式沉积在碱性过渡金属氧化物上时，开发不含贵金属的活性稳定的常温CO低温氧化催化剂仍然是一个重大挑战。在这里，我们报道了四氧化三钴纳米棒不仅在低至-77°C的温度下催化CO氧化，而且在正常原料气的潮湿流中保持稳定。高分辨率透射电镜显示，co3o4纳米棒主要暴露其{110}面，有利于活性Co3+物质在表面的存在。动力学分析表明，纳米棒上单个Co3+位点的转换频率与该材料的常规纳米颗粒相似，这表明我们在纳米棒形态下获得的显著更高的反应速率可能是由于表面丰富的活性Co3+位点。这些结果表明了形态控制在制备碱性过渡金属氧化物作为高效氧化催化剂中的重要性。
Low-temperature oxidation of CO, perhaps the most extensively studied reaction in the history of heterogeneous catalysis, is becoming increasingly important in the context of cleaning air and lowering automotive emissions,. Hopcalite catalysts (mixtures of manganese and copper oxides) were originally developed for purifying air in submarines, but they are not especially active at ambient temperatures and are also deactivated by the presence of moisture,. Noble metal catalysts, on the other hand, are water tolerant but usually require temperatures above 100 °C for efficient operation,. Gold exhibits high activity at low temperatures and superior stability under moisture, but only when deposited in nanoparticulate form on base transition-metal oxides,,. The development of active and stable catalysts without noble metals for low-temperature CO oxidation under an ambient atmosphere remains a significant challenge. Here we report that tricobalt tetraoxide nanorods not only catalyse CO oxidation at temperatures as low as –77 °C but also remain stable in a moist stream of normal feed gas. High-resolution transmission electron microscopy demonstrates that the Co3O4nanorods predominantly expose their {110} planes, favouring the presence of active Co3+species at the surface. Kinetic analyses reveal that the turnover frequency associated with individual Co3+sites on the nanorods is similar to that of the conventional nanoparticles of this material, indicating that the significantly higher reaction rate that we have obtained with a nanorod morphology is probably due to the surface richness of active Co3+sites. These results show the importance of morphology control in the preparation of base transition-metal oxides as highly efficient oxidation catalysts.