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Interactions of CO and NO with the perovskite‐type oxide larho 3
Author(s) -
Tascón Juan M. C.,
Olga Oliván A. M.,
Tejuca Luis G.
Publication year - 1986
Publication title -
journal of chemical technology and biotechnology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.64
H-Index - 117
eISSN - 1097-4660
pISSN - 0268-2575
DOI - 10.1002/jctb.280360306
Subject(s) - adsorption , oxide , chemistry , perovskite (structure) , metal , rhodium , inorganic chemistry , molecule , catalysis , crystallography , organic chemistry
Some aspects of the interactions of CO and NO with LaRhO 3 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 LaRhO 3 at 817 K, rhodium was obtained, highly dispersed on a matrix of La 2 O 3. 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 LaMO 3 oxides of group‐VIII metals. Coverages of CO(θ CO ) and NO(θ NO ) at room temperature were lower than 3%, θ NO being substantially higher than θ CO. 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 LaRhO 3 surface.