Co3O4-SiO2 Nanocomposite: A Very Active Catalyst for CO Oxidation with Unusual Catalytic Behavior
Co3O4-SiO2 Nanocomposite: A Very Active Catalyst for CO Oxidation with Unusual Catalytic Behavior
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DOI：
10.1021/ja2028926
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发表时间：
2011-07-27
影响因子：
15
通讯作者：
Schueth, Ferdi
中科院分区：
文献类型：
--
作者：
Jia, Chun-Jiang;Schwickardi, Manfred;Schueth, Ferdi
以活性炭为模板剂制备了高比表面积Co3O4-SiO2纳米复合催化剂。Co3O4-SiO2复合材料与普通Co3O4相比，其表面富含二氧化硅和Co（II）物种，即使在低至-76 ℃的温度下也表现出非常高的CO氧化活性。在正常进料气体（H2O含量类似于3ppm）下观察到相当不寻常的温度依赖性活性曲线，在约80 ℃下转化率最低。活性曲线的U形表明在一定温度范围内的负表观活化能，这是很少观察到的CO的非均相催化氧化Co3O4-SiO2催化剂的催化行为的仔细调查导致的结论，H2O分子在催化剂的表面上的吸附引起的异常行为。原位漫反射傅里叶变换红外（DRIFT）光谱实验在正常和干燥条件下支持这一结论。
A high surface area Co3O4-SiO2 nanocomposite catalyst has been prepared by use of activated carbon as template. The Co3O4-SiO2 composite, the surface of which is rich in silica and Co (II) species compared with normal Co3O4, exhibited very high activity for CO oxidation even at a temperature as low as -76 degrees C. A rather unusual temperature-dependent activity curve, with the lowest conversion at about 80 degrees C, was observed with a normal feed gas (H2O content similar to 3 ppm). The U-shape of the activity curve indicates a negative apparent activation energy over a certain temperature range, which has rarely been observed for the heterogeneously catalyzed oxidation of CO. Careful investigation of the catalytic behavior of Co3O4-SiO2 catalyst led to the conclusion that adsorption of H2O molecules on the surface of the catalyst caused the unusual behavior. This conclusion was supported by in situ diffuse reflectance Fourier transform infrared (DRIFT) spectroscopic experiments under both normal and dry conditions.