原位FT-IR研究甲烷和氧与SrO-La_2O_3/CaO催化剂表面的相互作用和反应(英文)

用原位FT－IR研究了甲烷和氧与纯CaO，La_2O_3和SrO氧化物以及LC和SLC催化剂的相互作用和反应．当不存在气相氧时，引入的甲烷与表面晶格氧反应生成碳酸盐物种。在室温或高温下，在这些氧化物和催化剂上不能检测到CH_4或O_2的吸附物类。但是，当CH_4和O_2同时存在时，在La_2O_3和LC催化剂上能检测到1118cm~－1的新谱带、这一谱带可能来自于表面碳酸盐在高温下氧气氛中的分解，并可归属为物种。甲烷与这一活性氧物种反应生成C_2H_4。但对SLC催化剂，在高温下不能检测到物种，而甲烷和氧在高温下反应也能产生表面碳酸盐并在气相中形成乙烯，这就表明，气相氧对这些催化剂也起着关键作用，但是在LC和SLC催化剂上甲烷氧化偶联反应可能有本质上的差别。

AN IN SITU FT-IR STUDY ON THE INTERACTION AND REACTION OF CH4 AND O2 WITH THE SURFACE OF SrO-La2O3/CaO CATALYSTS

The interaction and reaction of CH4 and miXture of CH4 and O2With pure oxides of CaO, La2O3, SrO, La2O3/CaO(LC) and SrO-La2O3/CaO(SLC) catalysts were studied by in situ FT-IR. When CH4 is introduced overthe catalysts in the absence of gas phase oxygen, it reacts with surface latticeoXygen to form carbonate species. Neither CH4 nor O2 adspecies weredetected on these catalyst surfaces at room and high tempeyatures.Meanwhile, it is noteworthy that there is a new band at 1118 cm-1 for La2O3and LC catalysts when CH4 and O2 are both presented. This band is fromthe decomposition of surface carbonate in oxygen at high temperatUres andcan be assigned as O2- species. CH4 reacts with the active oxygen species toform C2H4. With SLC catalyst, no O2- active oxygen species were detectedat high temperatures. But the reaction of CH4 and oxygen at hightemperatures produces surface carbonates and C2N4 in the gas phase. Thisindicates that the gas phase oxygen plays a key role for these catalysts andthere are some differences in the nature of the OCM reactions over LC andSLC catalysts.