Direct decomposition of nitrogen monoxide on (Ho, Zr, Pr)2O3 + δ Catalysts

• Ho2O3-based catalysts exhibit high NO decomposition activity.
• The catalysts show high tolerance to O2 and CO2 coexistence.
• The praseodymium ions in the lattice facilitate O2 desorption to increase the NO decomposition activity.

C-type cubic holmium oxide (Ho2O3), which has a large number of basic sites, was employed as a host material for NO decomposition catalysts, and zirconium and praseodymium ions were introduced into the lattice to increase the surface area and to control O2 desorption ability of Ho2O3, respectively. The highest catalytic activity was obtained for (Ho0.87Zr0.05Pr0.08)2O3.05 + δ, on which the NO conversion to N2 was as high as 71% at 900 °C in the absence of coexisting gases (NO/He atmosphere). The catalytic activity was maintained at a high conversion ratio even in the presence of the coexisting gases; the N2 yields of 50% and 47% were obtained even in the presence of 5 vol% O2 and CO2, respectively.

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