CuO/γ-Al_2O_3上CO和NO吸附的红外光谱研究——Ⅱ.还原态

An Infrared Spectroscopic Study of CO and NO Adsorption on CuO/γ-Al2O3 Ⅱ . Reduced Sample

应用红外光谱技术研究了CO和NO及其混合气体在还原态CuO/γ-Al_2O_3上的吸附.XRD分析样品物相仅有Cu^0,但是,XPS和IR都证明样品表面上除Cu^0外,还有Cu^(2+)和Cu^+。CO以分子态的形式吸附在Cu^+和Cu^0上(低于173K,无NO存在时,CO可以吸附在Cu^(2+)上);NO以分子态吸附在Cu^(2+)上,在Cu^0上为离解吸附(173K以下,无CO存在时,NO可以吸附在Cu^+上)。CO吸附时,表面还生成HCO_3^-、CO_3^(2-)、HCOO^-,NO吸附时,除被氧化为NO3^-外,表面上还出现N_2O物种;高于室温时,CO和NO共吸附,表面上除生成HCO_3^-、CO_3^(2-)和N_2O外,还有NCO^-物种生成,讨沦了CO和NO反应的基本步骤。

The adsorption and reaction of CO and NO on reduced CuO/γ-Al2O3 were studied by infrared spectroscopy. The composition of bulk phase and the valence states of surface copper ions were measured by XRD and XPS methods. The bulk phase was composed of Cu0, XPS and IR indicated that, besides Cu0, Cu2+ and Cu+ existed on the surface of sample.CO can be adsorbed on the Cu0 and Cu0 sites, NO can be adsorbed on the Cu2+sites, and it may be dissociatively adsorbed on Cu0 above room temperature. The species of HCO3-, CO32- and HCOO- formed on the surface for CO adsorption. NO3- and N2O were found on the surface for NO adsorption. During CO and NO coadsorption, the HCO3-, CO32- , N2O and NCO- were detected on the surface, the elementary steps of (CO+NO) reaction were discussed.