SO2气氛下Cu-Ce-O催化剂氧化柴油车排气碳烟的性能

运用程序升温氧化(TPO)对共沉淀法合成的Cu-Ce-O催化剂进行了活性评价,考察了在不同浓度的S0,气氛下cu-Ce-O催化剂氧化模拟碳黑的性能,并用BET、XRD、TPR和FT-IR对催化剂进行了表征.BET和XRD测试显示,cu和ce的结合使催化剂比表面积增大,晶体结构发生变化,形成了复合氧化物;TPO活性测试结果表明,Cu-Ce-O复合催化剂比单一组分的CuO或CeO2具有更好的低温催化活性.复合氧化物cu-Ce-O中Cu原子含量越高,对应硫化后的催化剂氧化碳烟的能力越低,同时催化剂表面生成的硫酸盐越多,即催化剂抗硫中毒能力也降低.浓度低于0.03%的SO2对Cu-Ce-O的催化性能有一定的促进作用,但SO2的体积分数超过0.03%后碳黑燃烧速率变慢;FT-IR初步证实了高体积分数的SO2所产生的大量SO24-可能是抑制催化剂活性的原因.

Oxidation of diesel soot over Cu-Ce-O catalysts in an atmosphere containing SO2

Cu-Ce-O catalysts were prepared by co-precipitation and their catalytic behavior was investigated by Temperature Programmed Oxidation (TPO) for model soot oxidation in a feed gas containing various concentrations of SO₂.The catalysts were characterized by BET,XRD,TPR and FT-IR.The BET and XRD results showed that the combination of Cu and Ce oxides increased their specific surface area,changed the crystal structure and formed complex oxides.TPO tests revealed that Cu-Ce-O complexes exhibited better activity than pure CuO or CeO₂ at lower temperatures.An increase in the Cu atomic ratio in sulfated Cu-Ce-O was accompanied by a simultaneous increase of the combustion temperature and the amount of surface sulfate,which could imply the deterioration of sulfur tolerance of those catalysts.SO₂ with concentration below 0.03% enhanced the catalytic performance of Cu-Ce-O,but the soot oxidation rate began to slow down at SO₂ feed concentrations above 0.03%.The FT-IR spectrum revealed that the introduction of high concentrations of SO₂ produced plentiful SO₂-4 on the catalyst surface,which could account for the loss of activity of the Cu-Ce-O catalysts.