Topological Aspect of the Distribution of Co Species and N₂O Decomposition Performance for Co/Zeolite Catalysts

In this study, series of Co/zeolites with diverse microporousstructureswere prepared and applied for N2O catalytic decomposition.The corresponding activities followed the order Co/Beta > Co/Mordenite> Co/ZSM-5 > Co/MCM-49 > Co/ZSM-23 > Co/ZSM-35 > Co/SSZ-13,whilethe yield of NO2 byproduct followed the order Co/ZSM-23> Co/ZSM-35 > Co/MCM-49 > Co/Mordenite > Co/ZSM-5 >Co/Beta > Co/SSZ-13.Under conditions of 30 vol % N2O and GHSV = 30 000h(-1), the best performing sample (Co/beta) achieveda remarkable N2O conversion of 99.6% at 450 & DEG;C. Inaddition, the formation of NO2 byproduct was significantlyinhibited with the corresponding concentration varying from 1063 ppmfor Co/ZSM-23 to 82 ppm for Co/Beta. Physicochemical characterizationof these as-prepared catalysts was performed including XRD, BET, H-2-TPR, NH3-TPD, XPS, UV-vis-DRS, and it was foundthat zeolites with higher dimensionally porous apertures (3D) andlarger pore sizes (12-membered ring, 12-MR) were conducive to introducingCo ions onto the zeolite framework through the pore channels and furtherlocating them on ion-exchange sites to form active centers (Co2+). Furthermore, molecular dynamics simulation demonstratedthat the higher pore dimensions and larger pore sizes are more beneficialfor the N2O diffusion inside the pores and channels ofzeolites and promote N2O decomposition.