加压条件下MgO/BaCO_3催化剂上甲烷氧化偶联反应性能及失活 Ⅱ.催化剂表面结构对其催化性能的影响

CATALYTIC PERFORMANCE OF MgO/BaCO3 FOR OCM AND ITSDEACTIVATION AT ELEVATED PRESSUREⅡ. Effect of the Surface Structure on Catalytic Performance

用ＸＰＳ，ＣＯ２－ＴＰＤ及ＣＯ与ＣＨ４的恒温脉冲反应技术，深入研究加压失活ＭｇＯ／ＢａＣＯ３催化剂表面结构变化对其催化性能的影响．结果表明，加压失活催化剂表面活性氧物种Ｏ２－２离子浓度大大降低；表面晶格氧的流动性及晶格氧参与甲烷转化的能力都大大减弱；由于加压失活催化剂表面结构发生变化，ＭｇＯ和ＢａＣＯ３共同作用形成的强碱中心消失．

The MgO/BaCO3 catalyst gradually lost its activity at elevated pressure and the surface structure of the catalyst was changed by pressure. This paper was aimed at investigating the effect of the catalyst surface structure on its performance for oxidative coupling of methane (OCM) by means of XPS, CO2TPD, CO and CH4 constant temperature pulse reaction (CTPR) techniques. The results showed that the changes of surface structure led the catalyst to decrease surface O2-2 concentration and to lower lattice oxygen mobility. Also, the strong basic sites on the deactivated catalyst disappeared.