4 research outputs found
An EXAFS study of the influence of CO chemisorption on the structure of highly dispersed Rh/TiO2 catalysts
An EXAFS study of the influence of CO chemisorption on the structure of highly dispersed Rh/TiO2 catalysts
An extended X-ray absorption fine structure spectroscopy study of a highly dispersed Rh/Al2O3 catalyst : the influence of CO chemisorption on the topology of rhodium
An Extended X-ray Absorption Fine Structure Study of Rhodium-Oxygen Bonds in a Highly Dispersed Rhodium/Aluminum Oxide Catalyst
Analysis of in situ EXAFS measurements on a 2.4 wt % Rh/A120, catalyst, reduced at 473 K after calcination at 623 K,
shows the presence of two different rhodium-oxygen bonds (viz. 2.05 and 2.68 A). The oxygen neighbors of rhodium at
a distance of 2.05 A disappear after reduction at 673 K. The coordination distance 2.05 A is the same as found for Rh203
and indicates that this rhodium-oxygen bond is present due to incomplete reduction of the catalyst at 473 K. Rhodium-oxygen
bonds with a coordination distance of 2.68 A are present at both reduction temperatures. These bonds arise from a coordination
of the interfacial rhodium atoms with the oxygen ions of the support. Assuming a half-spherical shape for the rhodium metal
crystallites, numerical values for the average interfacial rhodium-oxygen coordination number (N = 2.5) and the crystallite
diameter (d = 11 A) are derived from the experimental EXAFS parameters