| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 73167 | Microporous and Mesoporous Materials | 2014 | 8 Pages |
•Poisoning Na+ effect is the consequence of its activity as of Lewis acid.•Na+ cation changes the activation energy of the EFAL reactions.•The barrier variation depends on the oxygen atom type to be coordinated.•The concert mechanism for the limiting stage of the EFAL transformation.
The common main factor of the Na+ influence on the extra-framework aluminum (EFAL) transformations was observed while modeling partly hydrated zeolites at both periodic and cluster computational levels. It can be characterized as the attack of Lewis acid (Na+) toward electron pairs of different O atoms. The limiting step of EFAL formation is assigned to the transformation between the AlOH2+ and Al(OH)2+ species. It allows the explanation of the poisoning effect of Na+ on the cracking reactions known experimentally. The role of electrostatic factor is also discussed.
Graphical abstractThe concert mechanism for proton and Na+ exchange for the explanation of Na+ effect at the limiting stage of the EFAL transformation.Figure optionsDownload full-size imageDownload as PowerPoint slide
