Abstract: 12SrO·7Al₂O₃ was synthesized by solid reaction and was used as the washcoat to a La_0.8Sr_0.2MnO₃-cordierite monolith catalyst. The monolith catalyst was treated at different temperatures (850–1050 ^oC) and was characterized by N₂ adsorption-desorption, X-ray diffraction, and scanning electron microscopy. The catalytic activity of the monolith catalyst was evaluated using methyl methacrylate combustion. The results showed that the 12SrO·7Al₂O₃ washcoat improved the thermal stability of the monolith catalyst obviously. After calcination at 850 ^oC for 6 h, the monolith catalyst with the 12SrO·7Al₂O₃ washcoat could fully convert methyl methacrylate at about 260 ^oC. The 12SrO·7Al₂O₃ prevented the interaction between La_0.8Sr_0.2MnO₃ and cordierite and alleviated the sintering of La_0.8Sr_0.2MnO₃, and thus kept the structure and the dispersion of La_0.8Sr_0.2MnO₃ and enhanced the activity and thermal stability of the monolith catalyst.

Key words: perovskite, mayenite, cordierite, methyl methacrylate, catalytic combustion, thermal stability