Catalytic oxidation of CO by N2O on neutral Y2MO5 (M = Y, Al) clusters: a density functional theory study

Abstract

Density functional theory (DFT) calculations are employed to investigate the full catalytic cycle of CO oxidation by N₂O on yttrium oxide clusters Y₂MO₅ (M = Y, Al) in the gas-phase. Extensive structural searches show that both the ground-state structures of Y₃O₅ and Y₂AlO₅ contain an oxygen radical (O_t˙) which plays an important role in CO oxidation. Energy profiles are calculated to determine the reaction mechanisms. Molecular electrostatic potential maps (MEPs) and natural bond orbital (NBO) analyses are employed to rationalize the reaction mechanisms. The results indicate that the whole catalytic cycle for the reaction CO + N₂O → CO₂ + N₂, conducted by yttrium oxide clusters Y₂MO₅ (M = Y, Al), is favored both thermodynamically and kinetically. Moreover, compared with the previous report on di-nuclear YAlO₃⁺˙ and Y₂O₃⁺˙, it's obvious we can conclude that tri-nuclear Y₃O₅ and Y₂AlO₅ exhibit greatly enhanced catalytic activity toward CO/N₂O couples.