Mechanism of selective catalytic reduction of NOx with NH3 over CeO2-TiO2: Insight from in-situ DRIFTS and DFT calculations

The reaction mechanism over CeO2-TiO2 catalyst was investigated using in-situ DRIFTS spectra and density functional theory (DFT) calculations. DRIFTS results revealed that the SCR reactions on CeO2-TiO2 catalyst followed both E-R and L-H mechanisms. In the E-R mechanism, NH2NO species was considered as the reaction intermediate that decomposed into H2O and N-2. In the L-H mechanism, only adsorbed NO2 species reacted with NH3 to generate H2O and N-2. Based on the two mechanisms, the corresponding adsorption energy, activation energy barrier, and reaction heat in the process of NH3 adsorption and activation, NH2NO formation and decomposition, O-2 dissociation, and NO oxidation were calculated by DFT. By combining the DRIFTS and DFT results, the detailed reaction pathways over CeO2-TiO2 catalyst were obtained finally.

Automated summary

The reaction mechanism over CeO2-TiO2 catalyst involves both E-R and L-H mechanisms, with NH2NO species playing a key role as an intermediate. DFT calculations provide insights into the adsorption energy, activation energy barrier, and reaction heat for various steps in the process.