氧化还原预处理对一氧化碳低温氧化Pd/CeO2-TiO2催化剂性能的影响

The effects of oxidation and reduction pretreatments on the catalytic behaviors of Pd/CeO2-TiO2 catalyst for the low temperature oxidation of CO were investigated. The CeO2-TiO2 mixed oxides were prepared by sol-gel method. The H2-TPR measurements revealed that the reduction peak at 83 oC can be ascribed to the combined reduction of PdO and CeO2 on the support, and the interaction between Pd and the support becomes stronger with the increase of the reduction temperature, as convinced by the second cycle of the H2-TPR. The pretreatments of oxidation and reduction exhibit strong effects on the catalytic activity of Pd/CeO2-TiO2. The catalyst after high temperature oxidation at 500 oC and a successive reduction at low temperature at 150 oC gives the highest activity with the complete CO conversion at 48 oC in the 0.5% CO+1.6% O2+6.0%N2+Ar feedstock with a space velocity of 30,000 mL·h-1·g-1, which proved that an optimum interaction between Pd and the support is induced by such pretreatments. In the 0.6% CO+14.7% O2+55.3%N2+Ar flow, a complete conversion of CO reaches at ambient temperature and lasts for 12 h.