预处理条件对Au/Al_2O_3催化CO氧化性能的影响

Effects of Pretreatment Conditions on Catalytic Performance of Au/Al_2O_3 for CO Oxidation

采用沉积 沉淀法制备了Au/Al2 O3 ,探讨了预处理条件对催化剂中金颗粒的大小及其催化CO氧化性能的影响 ,并以XRD和TEM等手段对催化剂进行了结构表征 .结果表明 ,还原和焙烧预处理得到的 1 2 %Au/Al2 O3 催化剂在GHSV =1 5× 10 4h-1时 ,可分别于 - 2 2和 - 10℃将空气中的 1%CO完全氧化 ,还原预处理所得催化剂的活性更高 ,原因是催化剂中金颗粒的尺寸更小 ,分散度更高 .

In recent years, the study on supported gold catalysts has attracted much attention. Au/Al 2O 3 shows excellent performance in many catalytic reactions. Au/Al 2O 3 was prepared by deposition-precipitation method and characterized by TEM and XRD. The effects of pretreatment conditions on the gold particle size and catalytic performance of Au/Al 2O 3 for CO oxidation were studied in detail. The results show that 1.2%Au/Al 2O 3 pretreated by reduction and calcination can completely oxidize 1%CO in air to CO 2 at -22 and -10 ℃ respectively. The highest activity of Au/Al 2O 3 can be obtained when reduced at 250～300 ℃ for 30～60 min or calcinated at 250～300 ℃ for 180 min. The samples pretreated by reduction exhibit higher activity than those pretreated by calcination, by the reason that reduction pretreatment gives smaller gold particles, while calcination pretreatment gives bigger gold particles.