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

Abstract

Catalytic oxidations of NO with O2 over a number of catalysts were scanned with a tubular reactor at various times and temperatures. La0.8Sr0.2MnO3 and Pt/γ-Al2O3 gave the promising reactivity to catalyze this reaction. Under the conditions of 0.720s space time, 0.05vol% NO concentration, 5vol% O2 concentration and 473K, the steady-state conversion of NO oxidation over Pt/γ-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/γ-Al2O3 was the reaction between gaseous NO and dissociative O on the catalyst surface with activation energy of 80.01kJmol−1 in the temperature range 423–573K, 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 101.0kJmol−1 in the range of 373–473K.