ZrO2修饰Cu催化剂还原以及反应过程中表面组成的变化

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。

Surface species changes over ZrO2 modified Cu catalysts in the process of reduction and reaction

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.