Yamamoto T, Tanaka T, Matsuyama T, Funabiki T, Yoshida S
Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Japan.
J Synchrotron Radiat. 2001 Mar 1;8(Pt 2):634-6. doi: 10.1107/s0909049500017106.
Structural analysis of La/Al2O3 catalyst materials was carried out by means of XRD and La K-edge XAFS. Influences of loading amounts and treatment temperature on the local structure around La were investigated. La atoms are supported on gamma-Al2O3 in a highly dispersed form when a loading amount is less than 0.2 mmol g(Al2O3)(-1), and structural transformation of the La species does not take place in the temperature ranges of 873-1273 K. La species of highly loaded catalysts start to change their structure from oxide-like form to the aluminate at 1073 K. Formation of LaAlO3 perovskite on the catalyst surface requires a concentration of La atoms above 0.5 mmol g(Al2O3)(-1) (7.5 wt% as La2O3).
采用XRD和La K边XAFS对La/Al₂O₃催化剂材料进行了结构分析。研究了负载量和处理温度对La周围局部结构的影响。当负载量小于0.2 mmol g(Al₂O₃)⁻¹时，La原子以高度分散的形式负载在γ-Al₂O₃上，并且在873 - 1273 K的温度范围内La物种不会发生结构转变。高负载催化剂的La物种在1073 K时开始从氧化物状结构转变为铝酸盐结构。在催化剂表面形成LaAlO₃钙钛矿需要La原子浓度高于0.5 mmol g(Al₂O₃)⁻¹（以La₂O₃计为7.5 wt%）。
