Surface species changes over ZrO2 modified Cu catalysts in the process of reduction and reaction
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摘要: 通过热分解法制备Cu模型催化剂,然后经浸渍制备ZrO2/Cu催化剂,采用SEM、XPS考察了催化剂表面形态和组成,并采用in-situ Raman考察了催化剂在还原和吸附CO和水的过程中随时间的变化。结果表明,还原前Cu催化剂表面主要存在CuO物种,而在ZrO2/Cu表面,除了CuO物种,还存在着大量的表面羟基物种。ZrO2/Cu相对Cu更加容易还原为Cu0,同时,ZrO2在催化剂表面聚集形成絮状态,而Cu催化剂还原后主要形成Cu2O物种。Cu催化剂表面吸附CO后,除了形成Cu-CO外,Cu2O物种均会迅速消失形成CO2。Cu催化剂对水的作用比较弱,但是ZrO2/Cu催化剂和水作用较强,并且通过Cu-OH中间物形成Cu2O物种。Abstract: Cu model catalyst was prepared through thermal decomposition method and ZrO2/Cu was obtained through impregnation method. The morphology and surface composition of the catalysts were investigated using SEM and XPS. Surface specie changes over Cu and ZrO2/Cu in the process of the reduction were investigated using in-situ Raman. In the mean time, CO and H2O were passed through in sequence, and the Raman spectra were recorded. The results show that surface of Cu mainly consists of CuO species while that of ZrO2/Cu contains rich surface hydroxyl groups besides CuO species. ZrO2/Cu is easier to be reduced to CuO with ZrO2 species agglomerating to floccus state. However, Cu2O formed over Cu catalysts after reduction. CO adsorption over Cu produces Cu-CO with the disappearance of Cu2O and production of CO2. Water is weakly adsorbed over Cu but is adsorbed strongly over ZrO2/Cu to produce Cu2O species via Cu-OH intermediate.
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Key words:
- Cu /
- ZrO2/Cu /
- in-situ Raman /
- surface species
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