CeO_2及Pt/CeO_2催化剂上H_2、O_2的作用特性

THE CHARACTERISTIC BEHAVIOR OF H_2 AND O_2 OVER CeO_2 AND Pt/CeO_2 CATALYSTS

采用TPD、TPR、FT-IR和TPEC等方法研究了CeO_2及Pt/CeO_2上H_2、O_2作用特性。结果表明,Pt促进CeO_2还原,并形成高活动性氢物种。Pt的存在使吸H_2和放氢温度下阵达300℃。部分还原的CeO_2常温下吸附氧形成分子离子氧物种(O_2^-,O_2^(2-)),Pt的存在改变氧化铈催化剂在常温下氧吸附物种的形态,以解离态存在。氧化铈上吸附的氧物种在升温时可部分脱附,高于170℃时则转化为晶格氧。

The characteristic behavior of H_2 and O_2 over CeO_2 and Pt/CeO_2 was studied by means of TPR.TPD.FT-IR and TPEC. The reduction of CeO_2 by H_2 is greatly promoted by supported Pt and highly labile adsorbed species is resulted. The temperatures of sorption and liberation of H_2 on Pt/CeO_2 are lowered by as much as 300℃than on CeO_2. The oxygen adsorbed on partially reduced CeO_2 exists as dioxygenspecies(O_2^-,O_2^(2-)) at room temperature. On Pt/CeO_2 the oxygen species is altered andthe dissociated species is formed even at ambient condition. The adsorbed oxygen oncerium oxide catalysts desorbs partly while the temperature is elevated and the retai-ned oxygen is transformed into lattice oxygen ion above 170℃.