浸渍顺序对Ag-Pd/Ce0.8Zr0.2O2催化剂活性及脱附性能的影响

 采用不同的浸渍顺序制备了Ag-Pd/Ce0.8Zr0.2O2双组分催化剂,考察了催化剂对乙醇和CO氧化反应的催化活性,并对催化剂进行了TPD表征. 结果表明,浸渍顺序对催化剂的活性有很大的影响. 共浸渍催化剂的活性最高,其次为先浸渍钯后浸渍银的催化剂,先浸渍银后浸渍钯催化剂的活性最低. 催化剂上CO氧化活性与CO-TPD过程中CO2脱附峰的温度及强度有对应关系. 同时,乙醇氧化活性与C2H5OH-TPD过程中CO2脱附峰的温度有一定的对应关系. 这表明共浸渍催化剂的表面氧物种最活泼,最容易与吸附在催化剂表面的乙醇或CO发生氧化反应. 不同的浸渍顺序影响Ag或Pd的存在状态,共浸渍时有利于氧化态的形成; 但Ag状态的变化与催化剂上乙醇或CO氧化反应的活性没有对应关系.

Effect of Impregnation Sequence on Catalytic Activity and Desorption Property of Ag-Pd/Ce0.8Zr0.2O2 Catalyst

Ag-Pd/Ce 0.8 Zr 0.2 O 2 catalyst was prepared by conventional impregnation and characterized by TPD. The impregnation sequence had great effect on the activity of the catalyst for ethanol and CO oxidation. The catalyst sample co-impregnated with Ag and Pd had the highest activity, and the activity of the catalyst sample impregnated first with Pd then Ag was higher than that impregnated first with Ag then Pd. The activity of the catalyst samples for CO oxidation was corresponding with the temperature and intensity of CO 2 desorption peak in CO-TPD process. Simultaneously, the activity of the catalyst samples for ethanol oxidation was corresponding with the temperature of CO 2 desorption peak in C 2H 5OH-TPD process. This indicated that the oxygen species on the catalyst sample prepared by co-impregnation were the most active, and were easier to react with ethanol and CO adsorbed on the catalyst surface. Besides, the impregnation sequence affected the existing state of Ag or Pd, and the co-impregnation favored the formation of the oxidation state, but the change of Ag state had no relation with CO or ethanol oxidation reactivity.