焙烧温度对柴油车氧化催化剂Pt-Pd-（x）ZrO2/Ce0.3Zr0.7O2-Al2O3性能的影响

制备了氧化铝、铈锆固溶体复合氧化物负载铂、钯的双金属催化剂Pt-Pd/ Ce0.3Zr0.7O2-Al2O3，并添加3% ZrO2助剂改性，用于柴油车尾气中CO、HC和NO的催化氧化，其中贵金属负载量仅为0.68 wt%。考察了制备过程中焙烧温度对催化剂性能的影响。催化剂活性评价结果表明，与未添加ZrO2的催化剂比较。添加ZrO2明显提高了催化剂的低温氧化活性，而且焙烧温度对催化剂的氧化性能有较大影响。焙烧温度为800 ?C时，CO和C3H6的起燃温度最低，分别为168、189 ?C，焙烧温度为700 ?C时，NO转化为NO2的转化率最高，最大转化率为36%，具有较好的热稳定性。通过XRD、N2吸附-脱附、CO化学吸附、XPS、H2-TPR等表征手段考察了催化剂物理化学性质随焙烧温度的变化情况，并分析了与催化剂活性之间的关系，得到贵金属分散度、表面化学吸附氧含量、催化剂的还原性质对氧化性能有重要影响，发挥协同作用。进而可以通过优化焙烧温度提升柴油车氧化催化剂性能，对提高工业应用柴油车尾气后处理系统的净化效率有重要意义。

Influence of Calcination Temperature on Performance of Diesel Oxidation Catalyst Pt-Pd-(x) ZrO2/Ce0.3Zr0.7O2-Al2O3

Bimetallic Pt-Pd catalysts supported on Al2O3 and Ce0.3Zr0.7O2 with total Pt & Pd loading of only 0.68 wt% were prepared and used as diesel oxidation catalysts. 3% ZrO2 was then added into the system. Catalytic performance towards CO, C3H6 and NO oxidation over Pt-Pd-3ZrO2/Ce0.3Zr0.7O2-Al2O3 catalysts calcined at different temperatures were compared with catalyst without ZrO2 added. Catalytic activities evaluation results indicated that ZrO2 doping significantly enhanced the low-temperature oxidation activities. Furthermore, calcination temperature has great effects on the catalytic performance. The lowest light-off temperature of CO and C3H6 were obtained over ZrO2 modified catalyst calcined at 800 ?C and were 168 and 189 ?C, respectively. The optimal conversion of NO to NO2 was acquired when the calcination temperature is 700 ?C with the maximum conversion of 36%. The catalysts exhibited good thermal stability. XRD, N2 adsorption-desorption, CO chemisorption, XPS and H2-TPR were used to characterize the physical and chemical properties of catalysts calcined at different temperatures. It was found that noble metal dispersion, surface-chemisorbed oxygen species, and reducibility of catalysts mainly affected the catalytic performance synergistically. Thus, the catalytic oxidation activities could be improved by adjusting calcination temperature. The results are significant for improving purification efficiency of diesel catalytic system.