Adapted CO chemisorption technique to measure metal particle dispersion on ceria-containing catalysts

Abstract

Characterizing ceria-containing catalysts via common characterization techniques can be challenging. CO chemisorption is usually used to measure catalyst dispersion. However, the reaction between CO and ceria lattice oxygen leads to significant carbonate formation, resulting in an overestimation of the CO uptake and metal dispersion. Here, we propose a modified method to characterize ceria-containing catalysts which involves exposing the catalyst to CO2 prior CO adsorption to prevent further carbonate formation during CO chemisorption. We tested this method on Pd/CeO2 catalysts characterized by different ceria particle sizes and validated it via DRIFTS and CO oxidation kinetics. Validation conducted using CO oxidation kinetics showed that the TOFs derived by normalizing the reaction rates by the interfacial sites, which are the active sites, are similar for all the catalysts under investigation. Our results show that CO2-CO chemisorption can be a reliable technique for estimating metal dispersion of ceria-supported catalysts.