ZrO_2修饰Cu催化剂还原以及反应过程中表面组成的变化

Surface species changes over ZrO_2 modified Cu catalysts in the process of reduction and reaction

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。

Cu model catalyst was prepared through thermal decomposition method and ZrO2 / Cu w as obtained through impregnation method.The morphology and surface composition of the catalysts w ere investigated using SEM and XPS.Surface specie changes over Cu and ZrO2 / Cu in the process of the reduction w ere investigated using in-situ Raman.In the mean time,CO and H2 O w ere passed through in sequence,and the Raman spectra w ere recorded.The results show that surface of Cu mainly consists of CuO species w hile that of ZrO2 / Cu contains rich surface hydroxyl groups besides CuO species.ZrO2 / Cu is easier to be reduced to CuO w ith ZrO 2 species agglomerating to floccus state.How ever,Cu2 O formed over Cu catalysts after reduction.CO adsorption over Cu produces Cu-CO w ith the disappearance of Cu2 O and production of CO2.Water is w eakly adsorbed over Cu but is adsorbed strongly over ZrO2 / Cu to produce Cu2 O species via Cu-OH intermediate.