Interactions of CO and NO with the perovskite-type oxide larho3 |
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Authors: | Juan M. C. Tasc n,A. M. Olga Oliv n,Luis G. Tejuca |
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Affiliation: | Juan M. C. Tascón,A. M. Olga Oliván,Luis G. Tejuca |
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Abstract: | Some aspects of the interactions of CO and NO with LaRhO3 have been studied. The reduction of this oxide with CO occurs where the contracting sphere model is of perovskite structure stable up to a concentration of anion vacancies of ca. 2e? per molecule. By reduction of LaRhO3 at 817 K, rhodium was obtained, highly dispersed on a matrix of La2O3. After a reduction-oxidation cycle at 871 K the particle size of the perovskite decreased drastically. The activation energy of the reduction (67 kJ mol?1) was significantly lower than that of other LaMO3 oxides of group-VIII metals. Coverages of CO(θCO) and NO(θNO) at room temperature were lower than 3%, θNO being substantially higher than θCO. The reversibly adsorbed fractions of CO and NO underwent a remarkable decrease after preadsorbing NO and CO, respectively. This competitive adsorption is assumed to be associated with the adsorption of CO and NO on metallic sites. NO preadsorption inhibited the total adsorption of CO more severely than the reverse, indicating that NO is bound more strongly than CO to the LaRhO3 surface. |
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Keywords: | Perovskite oxides reduction of LaRhO3 CO and NO interactions with LaRhO3 |
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