Micro-mechanism of NO reduction in coal flue gas catalyzed by single atom Cu catalyst
Single-atom catalysts(SACs)exhibit high atomic utilization efficiency and superior catalytic activity,and have been widely applied in fields such as CO oxidation and CO2 reduction.The investigation of the micro-mecha-nisms of single-atom Cu catalysts in the catalytic NO reduction will contribute to the development of novel single-atom catalysts for the nitrogen oxides reduction.The parameters for quantum chemical calculations and model construction are described.The reaction pathways for NO reduction and N2O reduction,based on the Eley-Rideal(E-R)and Langmuir-Hinshelwood(L-H)adsorption mechanisms,are analyzed.Additionally,the kinetics of the NO reduction reaction are studied.Based on density functional theory and classical transition state theory,the micro-mechanisms of heterogeneous NO reduction in coal flue gas catalyzed by single-atom copper catalysts supported on graphene quantum dots(Cu/G)were investigated.The results indicate that the reduction process on Cu/G involves two stages:the for-mation of N2O and the formation of N2.Analysis of the energy barriers indicates that,within the Eley-Rideal(E-R)mechanism,the rate-determining steps for the sequential reduction of NO to N20 and subsequently to N2 exhibit lower energy barriers,with a value of 74.5 kJ/mol,compared to those observed in the Langmuir-Hinshelwood(L-H)mechanism.Kinetic analysis demonstrates that an increase in reaction temperature enhances the rate of NO reduction.Throughout the reaction process,the transfer of active oxygen leads to the consumption of graphene quantum dots,and a subsequent decline in the active oxygen transfer rate ultimately results in catalyst deactivation.The energy barri-er for the catalytic reduction of NO by single-atom Cu catalysts is lower than that of Cu metal clusters,indicating that the dispersion of metal atoms has a direct impact on catalytic activity.This also demonstrates the potential of single-at-om catalysis in NO reduction.
micro-mechanismdensity functional theorysingle-atom catalystsnitrogen oxidesclassical transi-tion state theorymodel configurationreduction pathway
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