Spray-made porous CuO-CeO2 microspheres rival precious metal catalysts for the low-temperature oxidation of air pollutants

Environmental constraints regarding the abatement of toxic gaseous pollutants such as carbon monoxide and various volatile organic compounds (VOCs) demand catalysts that can completely oxidize these molecules at low temperature. There is, however, a growing reluctance towards utilizing catalysts based on expensive and depleting precious metals such as Rh, Pd, and Pt. In this work, a continuous, one-step, and scalable procedure for the synthesis of high-performance copper-ceria catalysts is proposed. The aerosol-assisted sol-gel technique (AASG) allowed preparing porous CuO-CeO2 catalysts with high specific surface area (up to 140 m2/g), highly dispersed copper oxide nanoparticles (3-5 nm) in close interaction with ceria crystallites (5-8 nm), high concentration of defects, and abundant reactive oxygen species. This resulted in unprecedented total oxidation activity levels for Cu-Ce-based catalysts. The best catalyst is almost on par with a state-of-the-art oxidation catalyst (based on Pd and Rh) in the total oxidation of ethylene. For CO oxidation, all the synthesized CuO-CeO2 catalysts reached 90% of conversion at about 85 C, clearly outperforming the benchmark catalysts by 20-30 C. The structural properties and superior performances of these new nanostructured copper-ceria catalysts were stable over a 30-hour period, without observable deactivation.