甲烷氧化偶联催化剂Li/MgO的结构及表面性质的研究

STUDY OF STRUCTURE AND SURFACE PROPERTIES OF Li/ MgO CATALYSTS FOR OXIDATIVE COUPLING OF METHANE

本文用XRD、TEM、XPS和荧光光谱等方法研究了一组不同Li^+含量的Li/MgO催化剂的结构及表面性质,并与它们的氧化偶联甲烷的催化性能相关联。结果表明,低配位O^(2-)(O_(3c)^(2-))是使甲烷活化的活性中心。O_(1s)结合能为531.9eV的氧物种是对甲烷氧化偶联反应的C_2选择性起作用的活性氧物种。

The structure and suface properties of Li / MgO catalysts with various Li+ content for oxidative coupling of methane have been studied using XRD, XPS, TEM and photolumincsccnce spcctroscopy in conjunction with traditional catalytic behavior measurement. A good correlation between C2 selectivity and relative intensity of surface oxygen species corresponding to an O1s XPS peak at 531.9eV has been obtained. As an increasing amount of Li+ was added, the ratios O3c2- / O4c2- increased, passing through a maximum at 10mol% Li+ and then decreasing. The variation of the ratios with Li content paralleled the conversion of CH4, suggesting O3c2- ions are the active sites responsible for methane activation.