摘要
CuO和MnO_2的混合氧化物是良好的氧化-还原反应催化剂,尤其是作为Hopcalite催化剂(CuO40％,MnO_260％),即使在-20℃,对CO氧化仍表现出较好的活性.CeO_2作为氧化还原催化剂的助剂也被广泛应用,在贵金属为主的汽车排气净化三效催化剂中加入CeO_2,可提高CO,NO,HC的转化率和贵金属的分散度.本文用TPR方法研究了铜锰两组元氧化物在加铈前后的氧性质,用XRD,ESR,XPS方法研究其固相性质,用H_2-O_2滴定研究样品的供氧能力,讨论了CeO_2对Cu-Mn-O/γ-Al_2O_3系统的影响.
TPR, XRD, XPS, ESR and H2-O2 pulse injection were used to study the reaction between H2 and oxygen in Cu-Mn-O(I) and Cu-Mn-Ce-O(II) supported on alumina, and their oxygen storage capacity and solid structure were also studied. The results show that the TPR traces of (Ⅰ) and (Ⅱ) are similar to that of Cu-O/y-Al2O3 and the TPR feature peaks of Mn-O, Ce-O are not seen; as CeO2 loading increases to more than 10%, the peak temperature of (Ⅱ) is lower than that of (Ⅰ); the reoxidizing(Ⅱ) prereduced is easier than(Ⅰ) prereduced. The presence of Ce inhibits the growth of the spinel phases (CuMn2O4) and makes Cu, Mn of high valence state more stable. There is Cu0 in(Ⅱ) prereduced but it disappears after reoxidation. H2-O2 titration indicates that the addition of CeO2 into(Ⅰ) enhances its oxygen storage capacity and the reaction between H2 and oxygen of the catalysts.
