Template-free mesoporous La0.3Sr0.7Ti1-xFexO3 +/-delta for CH4 and CO oxidation catalysis

The design of perovskite oxides with improved textural properties in combination with tunable composition variations is a forward-looking strategy for the preparation of next generation catalytic converter. In the present work we report the template-free synthesis of mesoporous solid solutions of La 0.3 Sr 0.7 Ti 1-x Fe x O 3± ? (0 <= x <= 0.5) and the study of their catalytic performance towards CH 4 and CO oxidation. Using an innovative polymer complex route, phase pure perovskite solid solutions with specific surface area of 65 m 2 g -1 and average pore size of 15 nm were prepared. The iron concentration increase led to a progressive enhancement of not only both concentration and transport of the charge carriers but also reducibility and oxygen desorption capability on the catalyst. As a result, we observed almost complete conversion of CH 4 and CO at 600 °C and 300 °C, respectively. Kinetic studies on methane oxidation showed that competing suprafacial and intrafacial reaction mechanisms coexist, and that the concentration of 30% of Fe maximizes the suprafacial contribution. Under reducing conditions at 600 °C the materials retained their structural and morphological integrity, showing superior stability. Finally, the reaction rate of CH 4 and CO conversion evidenced that our systems are by a maximum of 90 times more performing than other bulk and nanoporous Fe-based perovskites in literature (e.g. La 0.66 Sr 0.34 Co 0.2 Fe 0.8 O 3- ?), as a result their large surface area, intimate gas-solid contact and short intragrain oxygen diffusion pathways induced by the mesoporous structure.