Effect of magnesium substitution into Fe-based La-hexaaluminates on the activity for CH4 catalytic combustion

Abstract

With the introduction of Mg²⁺ into Fe-substituted La-hexaaluminate precursors, a series of monophasic LaMg_xFeAl_11−xO₁₉ (x = 0, 0.3, 0.7, 1) catalysts were prepared and tested as catalysts for CH₄ catalytic combustion. The results show that the introduction of an appropriate amount of Mg²⁺ (x = 0.7) could significantly enhance the catalytic activity of Fe-substituted La-hexaaluminates and promote the resistance to deactivation after calcination at 1300 °C. The beneficial effect of Mg²⁺ is attributed to the fact that the presence of Mg²⁺ not only increased the distribution of Fe³⁺ in the mirror planes of La-hexaaluminates but also effectively suppressed the generation of catalytically inactive Fe²⁺. Besides, the LaMg_0.7FeAl_10.3O₁₉ catalyst exhibits excellent stability for 100 h at 700 °C under the reaction conditions.