Influence of aluminium distribution on the diffusion mechanisms and pairing of [Cu(NH3)2]+ complexes in Cu-CHA
Abstract The performance of Cu-exchanged chabazite (Cu-CHA) for the ammonia-assisted selective catalytic reduction of NO x (NH3-SCR) depends critically on the presence of paired $${[{{{\rm{Cu}}}}{({{{{\rm{NH}}}}}_{3})}_{2}]}^{+}$$ [ Cu ( NH 3 ) 2 ] + complexes. Here, a machine-learning force field a...
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| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Nature Portfolio
2025-01-01
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| Series: | Nature Communications |
| Online Access: | https://doi.org/10.1038/s41467-025-55859-1 |
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| Summary: | Abstract The performance of Cu-exchanged chabazite (Cu-CHA) for the ammonia-assisted selective catalytic reduction of NO x (NH3-SCR) depends critically on the presence of paired $${[{{{\rm{Cu}}}}{({{{{\rm{NH}}}}}_{3})}_{2}]}^{+}$$ [ Cu ( NH 3 ) 2 ] + complexes. Here, a machine-learning force field augmented with long-range Coulomb interactions is developed to investigate the effect of Al-distribution and Cu-loading on the mobility and pairing of $${[{{{\rm{Cu}}}}{({{{{\rm{NH}}}}}_{3})}_{2}]}^{+}$$ [ Cu ( NH 3 ) 2 ] + complexes. Performing unbiased and constrained molecular dynamics simulations, we obtain unique information inaccessible to first-principle calculations and experiments. The free energy barrier for $${[{{{\rm{Cu}}}}{({{{{\rm{NH}}}}}_{3})}_{2}]}^{+}$$ [ Cu ( NH 3 ) 2 ] + diffusion between CHA-cages depends sensitively on both the local and distant Al-distribution. Importantly, certain Al-distributions and arrangements of neighboring $${[{{{\rm{Cu}}}}{({{{{\rm{NH}}}}}_{3})}_{2}]}^{+}$$ [ Cu ( NH 3 ) 2 ] + and $${{{{{\rm{NH}}}}}_{4}}^{+}$$ NH 4 + cations make paired $${[{{{\rm{Cu}}}}{({{{{\rm{NH}}}}}_{3})}_{2}]}^{+}$$ [ Cu ( NH 3 ) 2 ] + complexes exothermic with respect to separated configurations. Our results suggest that the NH3-SCR activity can be enhanced by increasing the Cu-loading and Al-content. The dynamic interplay between $${[{{{\rm{Cu}}}}{({{{{\rm{NH}}}}}_{3})}_{2}]}^{+}$$ [ Cu ( NH 3 ) 2 ] + and $${{{{{\rm{NH}}}}}_{4}}^{+}$$ NH 4 + diffusion is crucial for the $${[{{{\rm{Cu}}}}{({{{{\rm{NH}}}}}_{3})}_{2}]}^{+}$$ [ Cu ( NH 3 ) 2 ] + mobility and stresses the need to explore large systems including long-range Coulomb interactions when studying diffusion of charged species in zeolites. |
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| ISSN: | 2041-1723 |