Partial substitution of lanthanum with silver in the LaMnO3 perovskite: Effect of the modification on the activity of monolithic catalysts in the reactions of methane and carbon oxide oxidation
Partial substitution of lanthanum with silver in the LaMnO3 perovskite: Effect of the modification on the activity of monolithic catalysts in the reactions of methane and carbon oxide oxidation
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DOI：
10.1016/j.apcata.2007.11.004
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发表时间：
2008-02
影响因子：
5.5
通讯作者：
B. Kucharczyk;W. Tylus
中科院分区：
文献类型：
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作者：
B. Kucharczyk;W. Tylus
在沉积在整体金属载体上的LaMnO 3钙钛矿中用银部分取代镧增强了CH 4和CO氧化的催化活性。对于CH 4燃烧和CO氧化，La 1 − xAgxMnO 3钙钛矿中的最佳银含量（x）分别为0.2和0.1至0.3。在750°C下在具有最活性钙钛矿（La0.8Ag0.2MnO3）的整体式催化剂上获得的甲烷转化率总计为98.9%，并且在130小时后略微福尔斯（至97.6%）。在900°C下老化导致甲烷转化率明显下降，在750°C下降至67%。该催化剂在运行过程中活性的降低归因于SSA的降低和Ag+与Ag 0的比例的降低以及在钙钛矿表面上Mn 4+还原为Mn 3+。当催化剂在900°C下老化时，过程得到增强;偏析到表面上的金属银倾向于形成团聚体，并且催化剂表面的组成与LaMnO 3钙钛矿的组成相似。
Partial substitution of lanthanum with silver in the LaMnO3perovskite deposited onto a monolithic metal support enhances catalytic activity in the oxidation of CH4and CO. The optimal silver content (x) in the La1−xAgxMnO3perovskite amounts to 0.2 and ranges from 0.1 to 0.3 for CH4combustion and CO oxidation, respectively. Methane conversion obtained over the monolithic catalyst with the most active perovskite (La0.8Ag0.2MnO3) at 750°C totals 98.9% and falls slightly (to 97.6%) after 130h on stream. Ageing at 900°C accounts for a distinct decline in methane conversion, which drops to 67% at 750°C. The decrease in the activity of this catalyst during the run is attributable to the decreasing SSA and decreasing proportion of Ag+to Ag0and to the reduction of Mn4+to Mn3+on the perovskite surface. When the catalyst is aged at 900°C, the processes are enhanced; the metallic silver that segregates onto the surface tends to form agglomerates, and the composition of the catalyst surface is similar to the composition of the LaMnO3perovskite.