制备方法及焙烧温度对Co3O4/CeO2催化剂上CO低温氧化反应的影响

 分别采用沉淀氧化法、均匀沉淀法及络合燃烧法制备了Co3O4/CeO2复合氧化物催化剂,并在干燥及湿气条件下进行了CO氧化反应. 结果表明,采用沉淀氧化法经538 K焙烧制得的Co3O4/CeO2催化剂具有优异的CO低温氧化活性和较高的抗湿性能. 在196 K条件下,该催化剂上CO氧化的转化率为99%, 并且可连续保持400 min以上; 当温度上升到298 K时,经过 2400 min反应后, CO的转化率仍可达到94%; 当反应气中含3.1%湿气,温度为383 K时,经过2400 min反应后, CO的转化率仍保持在79%. 实验表明, Co3O4/CeO2催化剂的制备方法及焙烧温度对Co3O4与CeO2之间的相互作用有显著的影响,进而影响催化剂催化CO低温氧化的活性.

Effect of Preparation Method and Calcination Temperature on Low-Temperature CO Oxidation over Co3O4/CeO2 Catalyst

Co3O4/CeO2 mixed oxides were prepared by coprecipitation-oxidation, homogeneous precipitation, and complexation-combustion methods. The catalysts were used to catalyze low-temperature CO oxidation under dry and humid conditions. The Co3O4/CeO2 catalyst prepared by the coprecipitation-oxidation method followed by calcination at 538 K exhibited excellent activity and good resistance to water vapor poisoning. Remarkably, a CO conversion of 99% was achieved at a temperature as low as 196 K and was maintained more than 400 min under the dry condition. When the reaction was carried out at 298 K, a CO conversion of 94% was obtained after running the reaction for 2 400 min. Even when 3.1% steam was added, a CO conversion of 79% could be kept after 2 400 min time-on-stream at 383 K. It is suggested that the strong interaction between Co3O4 and CeO2 is closely related to the preparation route and the calcination temperature and plays a crucial role in the CO oxidation over the Co3O4/CeO2 catalyst.