Catalytic conversion of NO and CO into N-2 and CO2 by rhodium-aluminum oxides in the gas phase

The increasingly stringent emission regulations make it urgent to get a fundamental understanding on the catalytic behaviors of rhodium, the most efficient component in three-way catalysts (TWCs) to convert NOx into N-2. Herein, the catalytic conversion of NO and CO into N-2 and CO2 by gas-phase rhodium-aluminum oxide species (RhAlO0-3 and RhAl2O1-4) was identified by mass spectrometry and quantum chemical calculations. This finding represents a significant step in the field of gas-phase catalysis, given that only elementary reactions for this conversion are commonly observed because it is extremely challenging to rupture the strong N-O bond and couple the N-N bond as well as drive the resulting product to oxidize CO. It emphasized that a polarized Rh-Al bond in gas-phase species is indispensable and the RhAlO0,1 and RhAl2O1,2 species with direct Rh-Al bonding can be involved in catalytic NO reduction by CO.