Catalytic oxidation of NO with O2 over Pt/γ-Al2O3 and La0.8Sr0.2MnO3

Catalytic oxidations of NO with O-2 over a number of catalysts were scanned with a tubular reactor at various times and temperatures. La0.8Sr0.2MnO3 and Pt/gamma-Al2O3 gave the promising reactivity to catalyze this reaction. Under the conditions of 0.720 s space time, 0.05 vol% NO concentration, 5 vol% O-2 concentration and 473 K, the steady-state conversion of NO oxidation over Pt/gamma-Al2O3 and La0.8Sr0.2MnO3 reached 22.4% and 90.5%, respectively. A kinetic model consisting of 12 elementary reactions was developed to fit the experimental data. The results showed that the rate-limiting step of NO oxidation over Pt/gamma-Al2O3 was the reaction between gaseous NO and dissociative O on the catalyst surface with activation energy of 80.01 kJ mol(-1) in the temperature range 423-573 K, and that the rate-limiting step of NO oxidation over the most promising catalyst La0.8Sr0.2MnO3 was the desorption of NO2 from catalyst surface with activation energy of 101.0 kJ mol(-1) in the range of 373-473 K. (c) 2013 Elsevier B.V. All rights reserved.