锂在甲烷氧化偶联催化剂中的助催化作用

自Lunsford等首次报道在Li/MgO催化剂上的甲烷氧化偶联(OCM)以来,许多研究者相继报道了添加碱金属对该反应的影响,其中以Li的添加最受关注。Li在OCM反应中对提高C_2烃选择性的作用最为明显,因而弄清Li在这一反应中的作用十分必要。本文讨论了Li在几个有代表性的碱土(CaO)及稀土(La_2O_3)中的存在形式与生成C_2产物的关系。

The Function of Lithium as a Promoter in Oxidative Coupling of Methane

in this paper, the function of lithium as a promoter in oxidative coupling of methane is reported. Based on the determination of different lithium salts, the authors found that the addition of lithium sulphate showed a higher selectivity for C2 formation, that of LiNO3 gave better C2 yield, the difference of catalytical properties over the two catalysts is related to the different forms of lithium. In Li/CaO catalyst the active center is LiO] and in Li/La2O3 catalyst the active site is the surface non-stoichiometric oxide of La.O,. Additionlly, the difference of the relations between the structrue and catalytic properties of Li/La2C>3 and Li-La/CaO catalysts was studied as well. Based on the results of luminescence emission spectra determination, we also clarfied the interaction between Li and CaO, La2O3 correlated to the account of lithium.