钙钛矿型复合氧化物Ca_xSr_（1－x）TiO_3催化剂上的甲烷氧化偶联反应

OXIDATIVE COUPLING OF METHANE OVER Ca_xSr_(1-x)TiO_3 PEROVSKITE CATALYSTS

在固定床反应器上，评价了不同温度下钙钛矿型复合氧化物ＳｒＴｉＯ３和ＣａＴｉＯ３的组成变化对甲烷氧化偶联反应的影响．同时，利用ＸＰＳ和ＣＯ２－ＴＰＤ对催化剂的结构及其氧物种的反应特性进行了表征．结果表明：ＳｒＴｉＯ３和少量Ｃａ掺杂的ＣａｘＳｒｌ－ｘＴｉＯ３有利于在较低温度（９２３Ｋ）下催化反应的活性和选择性，而ＣａＴｉＯ３体系则在高温（１０７３Ｋ）下表现出较好的活性和选择性．钙钛矿型复合氧化物ＳｒＴｉＯ３和ＣａＴｉＯ３组成变化对不同温度下反应活性的影响与ＣＯ２－ＴＰＤ的脱附谱图有很好的平行关系．

CaxSr1-x TiO3 perovskite catalysts for the oxidative coupling of methane were evaluated in a fixed bed reactor. XPS and CO2-TPD also were used to characterize the surface properties of the catalysts. It was found that SrTiO3 and Ca0.1Sr0.9TiO3 can initiate the reaction at 923 K and exhibit quite well activity and selectivity for C2,while CaTiO3 and Ca0.9Sr0.1TiO3 catalysts are good at 1073 K. XPS measurements showed that the 01s spectra of the fresh and used Ca0.1Sr0.9TiO3 catalysts change a lot.CO2-TPD showed that the catalyst with good activity and selectivity at relatively low temperature gives a CO2 desorption peak between room temperature and 650 K,while the catalyst with good activity and selectivity at high temperature produces a smaller CO2 desorption peak between room temperature and 650 K and another desorption peak at 753 K. The parallel relationship between the reaction performances and CO2-TPD profiles of the CaxSr1-xTiO3 perovskite catalysts is obvious.