镧改性铁催化剂的研究 Ⅲ.镧改性铁催化剂的表面吸附性能

A STUDY OF LANTHANA-MODIFIED IRON CATALYSTS Ⅲ.SURFACE ADSORPTIVE PROPERTIES OF LANTHANA-MODIFIED IRON CATALYSTS

用XPS,IR和Cahn微量天平技术研究了Fe_2O_3/γ-Al_2O_3,Fe_2O_3-La_2O_3/γ-Al_2O_3和Fe_2O_3/La_2O_3/γ-Al_2O_3催化剂的表面吸附性能。结果表明,部分镧覆盖了催化剂表面,这部分镧优先堵盖CO的桥式吸附位,同时由于部分镧的覆盖,减少了CO和H_2的化学吸附量,但大大促进了(CO+H_2)的共吸附,提高了催化剂的再吸附能力。

The surface adsorptive properties of Fe2O3/γ-Al2O3, Fe2O3-La2O3/γ-A12O3 and Fe2O3/La2O3/γ-Al2O3 catalysts have been investigated by X-ray photoelectron spectroscopy, infrared spectroscopy and Cabn micro-balance.The results show that the addition of lanthana to Fe2O3/γ-A12O3 catalyst results in a partial coverage of the supported Fe crystallites with LaOx islands.These moieties block preferably the adsorption site for bridge-bonded CO, reduce the chemisorption capacity of CO and H2,but promote the co-chemisorption of CO and H2.Lanthana-modified catalysts improve also the readsorption capability.