在甲烷氧化偶联反应中碱、碱土、稀土金属氧化物之间的相互作用 Ⅱ.掺CaO的La_2O_3和掺La_2O_3的CaO催化剂的催化性能

INTERACTION BETWEEN ALKALI,ALKALINE EARTH AND RARE EARTH METAL OXIDES IN CATALYTIC OXIDATIVE COUPLING OF METHANE Ⅱ.CATALYTIC PROPERTIES OF CaO DOPED La_2O_3 AND La_2O_3 DOPED CaO CATALYSTS

报导了非Li催化剂CaO-La_2O_3和La_2O_3-CaO的催化性能。甲烷氧化偶联反应的活性测试表明:以共沉淀方法制备的CaO-La_2O_3催化剂除了具有较好的C_2选择性外,其活性明显高于其它样品,而且适用于较大的空速条件(100000h^(-1)),是一个有应用前景的催化剂。但这类催化剂表现出明显的热点效应。用XRD,SEM等技术研究了相应催化剂体系的晶胞参数变化规律以及颗粒分散程度,并同其催化性能进行了关联。

The function of surface lithium in the catalytic oxidative coupling of methane was studied by using XRD, SEM, ESR and IR-PAS techniques, the surface composition, structure and the activity of Li-Mn-MgO catalysts for the given reaction were determined. The experimental results revealed that there existed a parallel correlation between the C2 hydrocarbon yield and the lithium content of catalyst. The deactivation of the Li-containing catalysts was related to the loss of surface Li and the lost surface Li could be compensated by the bulk Li diffusing to the surface at proper temperature, however, the compensation was limited to a large extent.