Aritani H, Yamada H, Yamamoto T, Tanaka T, Imamura S
Faculty of Engineering & Design, Kyoto Institute of Technology, Japan.
J Synchrotron Radiat. 2001 Mar 1;8(Pt 2):593-5. doi: 10.1107/s0909049500014448.
To characterize the defect sites in the near-surface and bulk phase of Li-MgO and Li-La2O3-MgO, XANES at Mg K-edge and La L3-edge was applied. For Li-MgO, it can be suggested that Li doping at a low content (2.5 wt%) brings about the formation of defect species only in the near-surface. This is due to the localization of doped Li ions in the surface, and thus the catalytically active species containing [Li+ O-] type center exist in the surface region. After OCM reaction, the detect species are formed in the near-surface over MgO and Li-MgO. By addition of La2O3 to Li-MgO (La/(Mg+La)=0.25), the structural change during the reaction is almost suppressed in the surface. In addition, the Li-La2O3-MgO shows higher C2 selectivity than Li-MgO.
