摘要 : In this work, a kinetic model is developed for the reduction of CuIIsites by NO + NH3and the reoxidation of NH3-solvated CuIsites by O2and NO in Cu-SSZ-13. Fourier transform infrared (FTIR) spectroscopy and spatially resolved capi... 展开 In this work, a kinetic model is developed for the reduction of CuIIsites by NO + NH3and the reoxidation of NH3-solvated CuIsites by O2and NO in Cu-SSZ-13. Fourier transform infrared (FTIR) spectroscopy and spatially resolved capillary inletmass spectrometry (SpaciMS) measurements during transient reactor experiments are utilized to identify the rate parametersassociated with NO + NH3RHC (reduction half-cycle), proposed to occur via two distinct pathways involving adsorbed NH3andgas-phase NH3. The resulting NO + NH3RHC model is validated using spatiotemporal N2measurements covering a wide range oftemperatures (200-450 degrees C) and space velocities (53 000-640 000 h-1). N2O formation is observed and modeled during NO +NH3RHC, with quantitative validation under standard selective catalytic reduction (SCR) conditions. Experimentally measuredenthalpic and entropic changes associated with O2adsorption on NH3-solvated CuI(ZCu(NH3)2) complexes [Kamasamudram,K.et al.Catal. Today2010,151(3-4), 212-222], along with activation energies estimated computationally for the intercage diffusionof ZCu(NH3)2complexes [Paolucci, C. et al.Science2017,357(6 354), 898-903], are incorporated into a meanfield kinetic modelfor the low-temperature oxidation half-cycle (OHC). Significant NH3release is observed during the isothermal oxidation of CuIsites, attributed to desorption of NH3ligands from NH3-solvated CuIIdimers (Z2Cu2(NH3)4O2). Reduction of these dimericcomplexes leads to the consumption of one NO/CuII, contradicting the expected reduction stoichiometry. Inclusion of a globalArrhenius rate for the NO titration of Z2Cu2(NH3)4O2complexes provides accurate representations of standard SCR on reducedand oxidized catalysts, predicting transient NO and NH3consumption between 150 and 250 degrees C as a function of hydrothermal aging.Deactivation of low-temperature standard SCR by NH3is observed at high NH3pressures, modeled via the formation of superoxoamino (ZCu(NH3)3OO*) complexes during NH3titration of Z2Cu2(NH3)4O2complexes [Negri, C. et al.J. Am. Chem. Soc.2020,142(37), 15884-15896]. The redox kinetic model presented here provides a foundational description of active site redox duringlow-temperature standard SCR, combining the recent kinetic, spectroscopic, and computationalfindings on the mechanism ofstandard SCR over Cu-SSZ-13. 收起