Characterization of the Catalysts with Atomically Dispersed Pd and Rh on Alumina
Recent experimental studies have demonstrated that atomically dispersed or ionic clusters of precious metals show the highest activity in a number of oxidation reactions. Concentration of intrinsic centers on a surface of γ-Al2O3 that are capable to stabilize the supported precious metals in atomic and cluster forms is not that great and usually does not exceed 0.5 wt. % by metal. In the case of Pd and Rh containing catalytic systems there are two main processes known to be responsible for catalyst deactivation. The first one refers to the sintering of dispersed Pd while another process is related to the bulk diffusion of Rh ions into support. The present study aims in a developing of spectroscopic optical, EPR and catalytic (ethane hydrogenolysis) methods for characterization of Pd and Rh state on alumina-based catalysts containing ultra-low concentrations (as low as 0.02 wt. %) of the supported metals.