The effects of BaO on the catalytic activity of La1.6Ba0.4NiO4 in direct decomposition of NO

• La1.6Ba0.4NiO4-x%BaO(x = 5–20) composites are in-situ prepared and used for NO decomposition.
• La1.6Ba0.4NiO4-20%BaO shows N2 yield of 57% at 923 K and can last for at least 500 h.
• La1.6Ba0.4NiO4-20%BaO shows N2 yield of 51% at 923 K at molar ratio of O2 to NO equals 1:5.
• BaO plays an important role in NOx transportation and storage, favoring the progress of the reaction.

The La1.6Ba0.4NiO4-x%BaO (x = 0, 5, 10, 15, 20, 25, 30) catalysts were prepared by heating the mixture of Ba(NO3)2 and La1.6Ba0.4NiO4 in situ, and their catalytic performances were evaluated for NO direct decomposition. The results showed that the activities of the La1.6Ba0.4NiO4-x%BaO catalysts had been improved with the increasing of BaO amount. Among these catalysts, the La1.6Ba0.4NiO4-20%BaO exhibited the best catalytic performance for NO direct decomposition, and the yield of N2 kept 57% during 500 h at 923 K in the absence of O2, even the concentration of O2 was 0.2% in the feed, the N2 yield still up to 57% at 923 K. So much higher activity for the perovskite(-like) oxides catalysts at such reaction temperature was first observed. In order to understand the role of BaO, a serial of experiments and characterizations were carried out on the La1.6Ba0.4NiO4-x%BaO catalysts. The results revealed that the number of chemical adsorption oxygen adsorbed on the oxygen vacancies increased and the mobility of the lattice oxygen could be improved due to the BaO addition. Moreover, BaO may play an important role in NOx transportation and storage, which is favorable for the regeneration of the active sites.

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