Preparation of alumina-supported Pd and LaMnO3 catalysts with the site-selective deposition and their catalytic activity for NO–CO reaction

By the combination of the preparation techniques of intra-pore deposition of Pd and selective intra/extra-pore deposition of LaMnO3, two types of alumina supported Pd–LaMnO3 catalysts were successfully obtained. It was suggested from the reduction behavior of supported Pd–LaMnO3 catalysts that when both Pd and LaMnO3 coexisted in the alumina pores (Pd/LaMnO3/Al2O3), Pd and LaMnO3 existed in close proximity each other to appear the interaction and that when Pd and LaMnO3 exist separately in and out of alumina pores, respectively (LaMnO3out/Pd/Al2O3), the existing environment of Pd was similar to that in Pd/Al2O3. For NO–CO reaction, Pd/Al2O3 and LaMnO3out/Pd/Al2O3 showed comparable activity and N2/N2O selectivity, and Pd/LaMnO3/Al2O3 showed higher activity than and different N2/N2O selectivity from the two catalysts, revealing that the intimate Pd–LaMnO3 interaction is effective to modify the catalytic property of Pd species. The excellent catalytic property of Pd/LaMnO3/Al2O3 was sustained up to 800 °C of calcination temperature.

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► Selective deposition of LaMnO3 inside and outside of alumina pores is realized.
► Interaction between Pd and LaMnO3 appears when both species coexist in alumina pores.
► The interaction is effective to enhance the catalytic property for NO–CO reaction.
► The interaction is sustained up to 800 °C.