Enhancing catalytic activity of perovskite-based catalysts in three-way catalysis by surface composition optimisation

Abstract

Fe-based perovskites prepared with purposely lowered La-content, La1−yFeO3±δ (y=0, 0.1, 0.2, 0.33), by sol–gel synthesis were investigated for application in 3-way catalysis. It was proven by XPS that surface composition control can be achieved by controlling the bulk composition. The decrease of La-content leads to a lower La excess at the surface whereas the orthorhombic perovskite structure with smaller crystallite sizes remains unaffected. Catalytic activity of La1−yFeO3±δ was investigated under 3-way catalytic conditions. Surface composition optimisation strongly enhanced the catalytic performance of the perovskite by increasing the accessibility of the active Fe3+ sites on perovskite and segregated Fe2O3. The estimation of Arrhenius parameters showed that CO and propylene oxidation seemingly proceed on different sites.