Cu/CeO2 and Cu/Gd-Substituted CeO2 Aerogels as Active, Selective, and Stable COPROX Catalysts

Purifying hydrogen feedstocks necessitates preferential oxidation of carbon monoxide (COPROX), but traditional precious metal catalysts are poorly selective, while transition metal catalysts suffer from insufficient activity and stability. We report that Cu nanoparticles supported on CeO2 or Gd(III)-substituted CeO2 (GCO) aerogels deliver a rare combination of high activity, selectivity, and stability for COPROX. The reducing oxide disperses Cu and stabilizes its more active low-valent state. Aerogel-supported Cu oxidizes CO at low temperature but requires higher temperatures to oxidize H2 and, therefore, shows wide temperature ranges with >95% CO conversion and >95% selectivity vs H2. This performance is maintained for >16 h of continuous operation in dry or humidified reaction streams. The Cu/GCO aerogel is less active than Cu/CeO2 under dry feedstreams but experiences less loss of activity under humid conditions because the higher surface area of the former distributes surface-adsorbed water along the network and reacts it at oxygen vacancies. Aerogel-based architected catalysts offer an effective design route to achieve high and stable catalytic activity under industrially relevant conditions.

Automated summary

Cu nanoparticles supported on CeO2 or Gd(III)-substituted CeO2 aerogels exhibit high activity, selectivity, and stability for COPROX. The reducing oxide stabilizes the more active low-valent state of Cu, allowing for wide temperature ranges with high CO conversion and selectivity. The Cu/GCO aerogel maintains its performance for over 16 hours in both dry and humidified reaction streams.