Recognizing zeolite topologies for Cu2+ localizations with effective activities for selective catalytic reduction of nitrogen oxide

Cu-loaded zeolites are widely investigated in selective catalytic reduction of nitrogen oxide, but effects of zeolite topologies on formed active species and the changing tendency remain unexplored. In this work, catalytic turnover frequencies (TOF) of Cu loaded ZSM-5, Beta, MOR, and SSZ-13 were first determined. The topology-localized Cu species in these zeolites were analyzed by temperature-programmed reduction of H-2. Then Multiple Linear Regression distinguished TOF contributions (k(j), s(-1)center dot mol(-1)) of the Cu species. Density functional theory calculated NH3 dehydrogenation energy of the Cu species. As a result, topologies with more node atoms showed bigger k(j) and lower dehydrogenation energies simultaneously. The best topology in each zeolite was 10-membered ring (ZSM-5), 6-membered ring facing a 12-membered ring (Beta), 8-membered ring (MOR), and cha cage (SSZ-13). Moreover, cha cage-localized Cu2+ exhibited the largest k(j) and the lowest dehydrogenation energy among all the Cu species. This work reveals topology-catalysis relationships in the zeolite, which benefits zeolite design for enhanced catalytic performances.

Automated summary

In this study, the catalytic turnover frequencies (TOF) of Cu loaded ZSM-5, Beta, MOR, and SSZ-13 were determined, and the topology-localized Cu species in these zeolites were analyzed. Multiple Linear Regression was used to distinguish the TOF contributions of the Cu species, and density functional theory calculated NH3 dehydrogenation energy. The results showed that topologies with more node atoms exhibited higher TOF and lower dehydrogenation energy, and the best topology varied for each zeolite.