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

摘要

Using urea-H_2O_2 solution to remove NO by scrubbing is regarded as a relatively low-cost and promising denitrificationmethod. For a good understanding and further improvement, the mechanism investigation on the NO removal by ureacombined with H_2O_2 is essential. The denitrification mechanism is calculated and studied in detail by Quantum Chemistryin this paper. Results show that the most possible denitrification route is that oxidizing NO by H_2O_2to produce HNO_2 and then absorbing HNO_2 by urea to produce N_2, CO_2 and H_2O. The activation energy of NO oxidation by H_2O_2 (71.12 kJ/mol) is higher than that of HNO_2 absorption by urea (60.17 kJ/mol). This indicates reaction H_2O_2 + 2NO → 2HNO_2 is the ratedetermining step and more difficult to carry out. The constraints of the NO removal are coming from NO oxidation ratherthan absorption in solution. Improving NO oxidation rate is the key to denitrification. The theoretical results in this paperprovide theoretical basis and data reference for subsequent technological development.