Template-free mesoporous La0.3Sr0.7Ti1-xFexO3±δ for CH4 and CO oxidation catalysis

• Published in: Applied catalysis. B, Environmental Vol. 245; pp. 536 - 545
• Main Authors: Kayaalp, Buğra, Lee, Siwon, Klauke, Kurt, Seo, Jongsu, Nodari, Luca, Kornowski, Andreas, Jung, WooChul, Mascotto, Simone
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15-05-2019; Elsevier BV
• Subjects: Automotive parts; Catalysis; Catalytic converters; Charge transport; Conversion; Current carriers; Emission control equipment; Exhaust systems; Iron; Methane; Oxidation; Oxides; Oxygen; Perovskite; Perovskites; Pore size; Porosity; Reaction mechanism; Reaction mechanisms; SOFC; Solid solutions; Structural stability; Surface area; VOC; Reaction mechanism; Perovskite; VOC; Structural stability; SOFC
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2018.12.077

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•Mesoporous La0.3Sr0.7Ti1-xFexO3±δ solid solutions prepared by a template-free approach.•Materials activity as a function of the iron content was clarified.•Improved VOC conversion imparted by high surface area and intimate fluid-solid interactions.•Kinetic studies identified separate contributions of suprafacial and intrafacial reaction mechanisms on La0.3Sr0.7Ti1-xFexO3±δ as a function of Fe substitution.•Mesoporosity and crystal structure fully retained under high temperature reducing conditions.
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 La0.3Sr0.7Ti1-xFexO3±δ (0 ≤ x ≤ 0.5) and the study of their catalytic performance towards CH4 and CO oxidation. Using an innovative polymer complex route, phase pure perovskite solid solutions with specific surface area of 65 m2 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 CH4 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 CH4 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. La0.66Sr0.34Co0.2Fe0.8O3-δ), as a result their large surface area, intimate gas-solid contact and short intragrain oxygen diffusion pathways induced by the mesoporous structure.