摘要
利用ESR,XPS,XRD等手段研究了K_2CO_3/BaCO_3模型催化剂结构与催化性能的关联。结果表明;K_2CO_3添加量≤5％时,它能均匀地混溶在BaCO_3晶格中,为了保持BaCO_3晶格电中性,同时在BaCO_3晶格中产生空穴,这些空穴在高温下与氧作用,生成[K^+O^-]和O^-氧物种。K_2CO_3/BaCO_3催化剂表面[K^+O^-]和O^-中心的产生有利于甲烷氧化偶联反应。当K^2CO_3添加量>10％时,催化剂表面被形成的K_2CO_3晶格所覆盖,不利于甲烷氧化偶联反应。
The correlation of structure aad catalytic property of K2CO3/BaCO3 catalysts had been studied by GC, ESR, XPS, XRD. ESR studies showed that the dissolution of K2CO3 in BaCO3 lattice would result in the formation of (K+O-) and O- centets on the surface of catalysts. The methane conversion and C2 yield increased as K2CO3 loading increased up to 5 mol %, Both 'XRD and XPS results indicated that at this level, K2CO3 was homogeneously dissolved in the BaCO3 lattice. The formation of (K+O-) and O- centers 'on the surface promoted the oxidative coupling of methane. When K2CO3 loading exceeded 10mol %, crystalline K2CO3 was formed on the catalyst surface and the reac--tion was suppressed.
基金
国家教育委员会优秀年轻教师基金
