MnOx对Pt/CeZrO2催化剂在水汽和CO2环境下CO氧化的影响

以CeZrO₂固溶体为载体，发现MnO_x的添加能促进Pt/CeZrO₂催化剂的CO氧化性能，并研究了MnO_x含量对催化剂CO氧化活性及抗H₂O和CO₂性能的影响。结果表明，随着MnO_x含量增加，催化剂活性呈现先升高后降低的趋势，在MnO_x含量为0.5%（质量分数）时活性最佳。MnO_x的添加降低了Pt颗粒尺寸并影响催化剂还原性能从而促进反应活性。水汽和CO₂对Pt/CeZrO₂催化剂的CO氧化活性有抑制作用，而MnO_x的加入能显著提高催化剂的抗水汽和CO₂的能力。反应动力学结果表明，在Pt/CeZrO₂催化剂上，反应气中引入H₂O和CO₂后，CO的反应级数有明显升高，说明H₂O和CO₂在催化剂表面与CO竞争吸附，导致CO反应活性下降；而在Pt/MnO_x/CeZrO₂催化剂上，CO的反应级数略有升高，说明MnO_x的添加能有效抑制H₂O和CO₂与CO的竞争吸附，从而改善了催化剂的抗H₂O和CO₂性能。

Effect of MnOx on Pt/CeZrO2 catalyzed CO oxidation under water vapor and CO2 conditions

Adding MnO_x to CeZrO₂ solid solution carrier could effectively enhance Pt/CeZrO₂ catalyst activity for CO oxidation. The effect of the amount of MnO_x on catalytic activity and resistance of H₂O and CO₂ was studied. The results showed that the activity of Pt/MnO_x/CeZrO₂ catalyst was first increased and then decreased as MnO_x content was increased with a maximum activity at 0.5% (mass) MnO_x content. The addition of MnO_x improved catalyst activity by reducing Pt particle size and changing catalyst reducibility. The presence of H₂O vapor and CO₂ in feed gas suppressed activity of Pt/CeZrO₂ catalyst, which was effectively alleviated by MnO_x in the catalyst. Kinetic study revealed that CO reaction order was considerably increased with presence of H₂O and CO₂for the Pt/CeZrO₂ catalyst. Such a decline of catalyst activity might be due to competitive adsorption of H₂O and CO₂ over CO on catalyst surface. In contrast, the CO reaction order was slightly increased with presence of H₂O and CO₂ for Pt/0.5MnO_x/CeZrO₂ catalyst, implying that addition of MnO_x could suppress competitive adsorption of H₂O and CO₂ over CO on catalyst surface and hence improve resistance to H₂O and CO₂.