Quantum Chemical Study on the Reaction Mechanism of NO Removal by Urea Combined with Hydrogen Peroxide

Abstract

Using urea-H2O2 solution to remove NO by scrubbing is regarded as a relatively low-cost and promising denitrification method. For a good understanding and further improvement, the mechanism investigation on the NO removal by urea combined with H2O2 is essential. The denitrification mechanism is calculated and studied in detail by Quantum Chemistry in this paper. Results show that the most possible denitrification route is that oxidizing NO by H2O2 to produce HNO2 and then absorbing HNO2 by urea to produce N2, CO2 and H2O. The activation energy of NO oxidation by H2O2 (71.12 kJ/mol) is higher than that of HNO2 absorption by urea (60.17 kJ/mol). This indicates reaction H2O2 + 2NO → 2HNO2 is the rate-determining step and more difficult to carry out. The constraints of the NO removal are coming from NO oxidation rather than absorption in solution. Improving NO oxidation rate is the key to denitrification. The theoretical results in this paper provide theoretical basis and data reference for subsequent technological development.