碱—碱土—稀土催化剂发射光谱的研究

用Eu~(3+)的发射光谱探讨了O~-物种的形成。对M/MgO、M/CaO体系(M为碱金属)的研究发现,Li~+、Na~+可进入MgO晶格;Li~+、Na~+、K~+可进入CaO晶格。由于Li~+不能进入La_2O_3晶格,故不能形成O~-物种,表明不同的催化剂体系在甲烷氧化偶联反应中会形成不同的活性中心。

Studies on Emission Spectra of the Catalysts of Alkali Alkaline-Earth Rare-Earth Metal Oxides

The formation of O species in oxide catalysts was investigated by characterization of emission spectra of Eu3+ ion. The experimental results show that in M/MgO and M/CaO sys-tems(M = Li+, Na+ and K+) Li+ and Na+ can enter into the lattice of MgO, and Li+ , Na+ and K+ ions can enter into the lattice of CaO. These conclusions are in good agreement with what was found by Lunsford in his ESR studies. Based on the results of emission spectra investigation > an evidence that Li+ ion can not enter into the lattice of La2O3 in Li/La2O3 mixed oxide and, as a result, no O- species can be formed was gained. The obtained experimental data also provided some useful information about the coordination conditions for simultaneous entrance of both mono- and tri-valence ions into the lattice of alkaline-earth metal oxides.