摘要
合成了La_(0.8)Sr_(0.2)Co_(0.6)M_(0.4)0_3系列和Ln_(0.6)Sr_(0.4)CoO_3系列单相钙钛矿型复合氧化物。用程序升温脱附法研究了置换金属离子对氧的吸附-脱附特性的影响,并考察了置换金属离子对CH_4,n-C_4H_(10)的完全氧化催化活性的影响。对于La_(0.8)Sr_(0.2)Co_(0.6)M_(0.4)0_3系列,氧的吸附-脱附特性由置换金属离子的价态和氧化还原性所决定。容易生成非常原子价态的金属离子的置换有利于氧在晶格氧空位上的吸附,催化活性受置换金属氧化物自身活性的影响。对于Ln_(0.6)Sr_(0.4)CoO_3系列,氧的吸附-脱附特性由稀土离子半径决定,离子半径小有利于氧的吸附,催化活性与吸附(脱附)氧量的变化规律一致。
La0.8Sr0.2Co0.6M0.4O3 (M=Cu,Zn,Fe,Co,Ni,Mn) and Ln0.6Sr0.4CoO3 (Ln = La, Pr, Nd, Sm, Gd) perovskite-type oxide samples were prepared and from which the oxygen desorption was examined by TPD below 850℃. The catalytic activities of the samples for the combustion of n-butane and methane were also studied. In La0.8Sr0.2Co0.6M0.4O3, the modification of the oxygen desorption behavior by the partial substitution for M may be explained in terms of the number of oxygen ion vacancies and redox properties of M cation as well. The catalytic activities of La0.8Sr0.2Co0.6-M0.4O3 were affected by the foreign M ions. In Ln0.6Sr0.4CoO3, the oxygen desorption was found to increase with the increment of the atomic number, and the modification of the catalytic activity was in agreement with the amount of desorbed oxygen.
