Remarkable Enhancement of O2 Activation on Yttrium-Stabilized Zirconia Surface in a Dual Catalyst Bed

• Published in: Angewandte Chemie International Edition 2014-10, Vol.53 (42), p.11342-11345
• Main Authors: Richard, Mélissandre, Can, Fabien, Duprez, Daniel, Gil, Sonia, Giroir-Fendler, Anne, Bion, Nicolas
• Format: Article
• Language: English
• Subjects: Catalysis; Chemical Sciences; methane; Organic chemistry; Other; oxidation; oxygen exchange; singlet oxygen; Solid oxide fuel cells; yttrium-stabilized zirconia
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201403921

Yttrium‐stabilized zirconia (YSZ) has been extensively studied as an electrolyte material for solid oxide fuel cells (SOFC) but its performance in heterogeneous catalysis is also the object of a growing number of publications. In both applications, oxygen activation on the YSZ surface remains the step that hinders utilization at moderate temperature. It was demonstrated by oxygen isotope exchange that a dual catalyst bed system consisting of two successive LaMnO3 and YSZ beds without intimate contact drastically enhances oxygen activation on the YSZ surface at 698 K. It can be concluded that LaMnO3 activates the triplet ground‐state of molecular oxygen into a low‐lying singlet state, thereby facilitating the activation of the O2 molecule on the YSZ oxygen vacancy sites. This phenomenon is shown to improve the catalytic activity of the LaMnO3‐Pd/YSZ system for the partial oxidation of methane. A double bed is better: The exchange of O2 across an LaMnO3 catalytic bed leads to an enhancement of its activation on an yttrium‐stabilized zirconia (YSZ) surface. The O atoms of the YSZ lattice, which are unable to exchange with gas‐phase O2 below 823 K, become exchangeable from 533 K in a dual LaMnO3‐YSZ bed. This property makes the dual LaMnO3‐Pd/YSZ catalytic system highly active for CH4 combustion and partial oxidation at moderate temperatures.