【摘要】 本文采用了ＣＯ２程序升温脱附（ＣＯ２－ＴＰＤ）、ＣＯ２分步热脱附（ＣＯ２－ＳＴＤ）、ＣＯ２气氛中电导测量和ＣＯ２作为甲烷氧化偶联反应（ＯＣＭ）稀释气等方法，研究了在受主掺杂ＣａＴｉＯ３体系的ＯＣＭ反应中ＣＯ２的作用．受主杂质Ｌｉ＋、Ｍｇ２＋、Ａｌ３＋掺杂的ＣａＴｉＯ３系列催化剂在制备过程或ＯＣＭ反应过程中能吸附大量ＣＯ２，ＣＯ２吸附量与气氛中ＣＯ２的分压及吸附温度等因素有关．大部分吸附的ＣＯ２与催化剂中的Ｃａ（ＯＨ）２作用形成了ＣＯ３－，少部分与催化剂晶格中的活泼氧物种Ｏδ－结合形成了．在Ｈｅ气氛中６００℃时开始分解释放出ＣＯ２，７５０℃以上开始分解同时使活泼氧物种Ｏδ－裸露出来．ＣＯ２吸脱附过程是可逆的．在ＣＯ２中测量样品电导的结果表明，吸附的ＣＯ２还可能捕获价带中的正导电空穴ｈ＇，使样品的Ｐ型电导下降，从而减少了催化剂中活泼氧物种Ｏδ－的浓度，加之ＣＯ２可使Ｏδ－形成不活泼的因此ＣＯ２的存在降低了ＯＣＭ反应中Ｃ２烃的选择性．更多还原

【Abstract】 he effect of CO2 on acceptor-doped CaTiO3 catalyst for oxidativecoupling of methane (OCM) was studied by means of CO, temperatureprogrammed desorption (CO2-TPD), CO2 stepwise thermal desorption(CO2-STD) and conductivity measurement in CO2 etc. It was shownthat acceptor doped CaTiO, catalyst could adsorb CO, during the preparing process of catalyst or the reaction process for OCM, the adsorbedamount depended on CO2 concentration in the atmosphere and adsorption temperature. It was also found that the adsorbed CO2 mainly reacted with Ca(OH)2 existed in the catalyst to form CaCO3 which could decompose at 650℃ and also combined with active oxygen species Oδ- existed on the lattice of catalyst to form which could decomposeover 750C. Conductivity measurement indicated that adsorbed CO2could trap positive hole h from valence band resulting in a decrease ofp-type conductivity, in addition, adsorbed CO, could result in a poisoning of Oδ- from CO2-STD measurement, therefore CO2 was not beneficial to the C2 selectivity for OCM reaction.更多还原