Effect of B‐site cation on the catalytic activity of La1−xCaxBO3 (B = Fe,Ni) perovskite‐type oxides for toluene combustion

Background The effect of the B cation on the surface properties and catalytic activity in the total combustion of toluene over La_1?xCa_xBO₃ (B = Fe,Ni) perovskite‐type oxides was studied. Result For the La_1?xCa_xFeO₃ series, the perovskite structure was maintained in the range of substitution studied. A completely different behaviour was observed for the La_1?xCa_xNiO₃ series. A Brownmillerite‐type structure (La₂Ni₂O₅) with a large degree of phase segregation as well dispersed mixed oxides was observed upon the substitution of La for Ca. In the Fe series, the catalytic activity in the total combustion of toluene showed that the insertion of calcium ions into the perovskite lattice resulted in higher activity relative to the unsubstituted LaFeO₃ perovskite. In contrast, for the Ni series, substitution results in solids with lower activity than the pure LaNiO₃ perovskite. Conclusion For the Fe series, higher activity and stability are attributed to a synergy between Fe⁴⁺/Fe³⁺ and the oxygen vacancies generated by the calcium substitution. For the Ni counterpart, the structural modification leads to a lower activity of substituted solids compared with the pure LaNiO₃ perovskite, indicating that Ni³⁺ ions are the active sites for toluene oxidation. Copyright © 2011 Society of Chemical Industry