Study of the Catalytic Oxidation Mechanism and Apparent Kinetics of NO Oxidized by H₂O₂ with Fe/β, Fe/SSZ-13, and Fe/ZSM-5

Abstract

Three iron-modified zeolites were prepared by impregnation, and their catalytic performance was evaluated for the catalytic oxidation of NO with H2O2. The structural characteristics of the catalysts, surface acidity distribution, type and relative content of iron species, and the generation of active sites during the reaction were analyzed in depth using various characterization techniques. The results showed that Fe/β and Fe/ZSM-5 exhibit better catalytic performance than Fe/SSZ-13 due to the most abundant Fe species sites and Brønsted acid sites. The possible mechanism of catalytic oxidation can be described as follows: •OH is generated by the interaction of Fe3+ with the carrier and strongly electrophilic NO+ is formed by adsorption and activation of NO by the Brønsted acid site, which together provides the catalytic function. Finally, the apparent kinetics of NO oxidation by Fe/zeolite catalysts catalyzed by H2O2 was established, and the effects of NO/SO2/H2O2 concentration and catalyst dosage on the NO oxidation rate were investigated.

Kinetics of Nitric Oxide Absorption from Flue Gas Using an Advanced Oxidation Process with Sodium Persulfate Solution

“…The rise rate of small bubbles was less than that of large bubbles; in another word, the elevated concentration of sodium persulfate not only augmented the oxidation capability but also significantly improved the productive interactions between the oxidative free radicals and the gas molecules. ,, Continuously increasing the Na 2 S 2 O 8 concentration until 0.15 mol/L caused the absorption rate of NO to increase from 3.89 × 10 –6 mol/(m 2 ·s) to 4.60 × 10 –6 mol/(m 2 ·s). The increase was more significant compared with the Na 2 S 2 O 8 /freshwater solution, and similar with the UV/H 2 O 2 method . However, it did not mean that the increase of the Na 2 S 2 O 8 concentration only changed the solution viscosity to improve the NO absorption rate.…”