THE NATURE OF RH-CO INTERACTIONS ON SAPO-5-SUPPORTED RH

The adsorption of CO on Rh/SAPO-5 showed the formation of a high-frequency dicarbonyl species that depended on time and temperature of adsorption as well as on the presence of oxygen. Other adsorbates including H2, water, and surface carbon inhibited the formation of this species, which was held tightly to the SAPO-5 support but was also shown to be labile for CO exchange. This dicarbonyl species was proposed to be due to a Rh/(CO)2 cationic species which may serve as the neutralizing cation in the ion-exchangeable SAPO-5 structure. This study combined with observations made in other work helped to construct a more coherent picture of the nature of the RhCO interaction on molecular sieve supports. © 1990.