Direct decomposition of nitric oxide over stannate pyrochlore oxides: relationship between solid-state chemistry and catalytic activity

✍ Scribed by Yasutake Teraoka; Ken-ichiro Torigoshi; Hidetoshi Yamaguchi; Takashi Ikeda; Shuichi Kagawa

• Book ID: 104424688
• Publisher: Elsevier Science
• Year: 2000
• Tongue: English
• Weight: 197 KB
• Volume: 155
• Category: Article
• ISSN: 1381-1169
• DOI: 10.1016/s1381-1169(99)00320-9

✦ Synopsis

Rare-earth stannate pyrochlores were synthesized and their NO decomposition activity was investigated in relation with Ž . the solid-state property. For pyrochlores free from transition metal substituents, Ln Sn O Ln s Y, La, Nd, Sm, Gd and 2 2 7 X Ž X . La Ln Sn O Ln s Nd, Sm , the strength of an Sn-O bond evaluated from its stretching IR band decreased almost 2yx x 2 7 linearly with increasing cubic cell parameter or the size of rare earth ions. The catalytic activity for the NO decomposition changed significantly with the sort of rare-earth ions, and oxides having the intermediate Sn-O bond strength showed the Ž . highest NO decomposition activity. For La Sn M O M s 3d transition metals, TM , the redox property of TMs was 2 1.9 0.1 7

responsible for the NO decomposition activity, and the Co-substituted oxide showed the highest activity. Changes in activity for both the TM-free and TM-substituted systems were discussed on the basis of the redox-type reaction mechanism in which oxide ion vacancies are active sites.