Catalytic Oxidation of CO by N2O Enabled by Al2O2/3+: Temperature Dependent Kinetics and Statistical Modeling.

The reactions of Al2O2+ + N2O and Al2O3+ + CO, forming a catalytic cycle oxidizing CO by N2O, have been investigated from 300 to 600 K in a variable ion source, temperature adjustable, selected-ion flow tube (VISTA-SIFT). Reaction coordinates have been calculated using density functional theory and statistical modeling of those surfaces compared to experimental kinetics data for mechanistic insight. The reaction of Al2O2+ + N2O proceeds at the Su-Chesnavich collisional limit at all temperatures studied, yielding only Al2O3+, with the exception of a small (<5%) amount of association product, Al2O2(N2O)+ at 300 K. The reaction of Al2O3+ with CO produces Al2O2+ with a rate constant of 4.7 ± 1.2 × 10-10 cm3 s-1 at 300 K, decreasing with temperature as T-0.5±0.2. In addition, a significant amount of association product, Al2O3(CO)+, was observed with rate constants for formation ranging from 10-11 to 10-10 cm3 s-1 dependent upon He buffer gas concentration and temperature. Implications of these kinetic measurements with regard to the reactive surface are discussed.