Mechanism of Zeolite Hydrolysis under Basic Conditions
Popis výsledku
Identifikátory výsledku
Kód výsledku v IS VaVaI
Výsledek na webu
https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=sfIy0ThMuu
DOI - Digital Object Identifier
Alternativní jazyky
Jazyk výsledku
angličtina
Název v původním jazyce
Mechanism of Zeolite Hydrolysis under Basic Conditions
Popis výsledku v původním jazyce
The controlled desilication of zeolites, leading to hierarchical micro-/mesoporous materials, is one of the most promising approaches to increase the application potential of zeolites. It can lift the restrictions connected to diffusion limitations in many industrially important processes and it can also modify the Si/Al ratio of the final material. The selective desilication of zeolites is generally performed under alkaline conditions, and control over the degree of framework degradation is maintained via the Si:Al ratio of the parent sample and the pH of the solution. However, the mechanism of alkaline hydrolysis in zeolites is poorly understood at present: The role of microsolvation of ions and the role of micropore confinement effects are currently unknown. In this work, we establish the mechanisms for the alkaline hydrolysis of siliceous zeolite chabazite (CHA) occurring from within the pore. Energetically facile reaction pathways are identified, which directly involve NaOH and confirm that NaOH may not only play a role as a reactant but also as a catalyst. We demonstrate that collective effects play a decisive role in the mechanism: initiation of the reaction via formation of Q3 defects becomes spontaneous when the Na+ cation is solvated by a sufficient amount of water and subsequent barriers along the desilication pathway are lowered. We show that it is crucial to include a realistic treatment of the hydration environment to capture the processes, which occur inside zeolite pores. This work advances our understanding of a ubiquitous process in heterogeneous catalysts and will help in controlled desilication treatments for zeolite upgrading.
Název v anglickém jazyce
Mechanism of Zeolite Hydrolysis under Basic Conditions
Popis výsledku anglicky
The controlled desilication of zeolites, leading to hierarchical micro-/mesoporous materials, is one of the most promising approaches to increase the application potential of zeolites. It can lift the restrictions connected to diffusion limitations in many industrially important processes and it can also modify the Si/Al ratio of the final material. The selective desilication of zeolites is generally performed under alkaline conditions, and control over the degree of framework degradation is maintained via the Si:Al ratio of the parent sample and the pH of the solution. However, the mechanism of alkaline hydrolysis in zeolites is poorly understood at present: The role of microsolvation of ions and the role of micropore confinement effects are currently unknown. In this work, we establish the mechanisms for the alkaline hydrolysis of siliceous zeolite chabazite (CHA) occurring from within the pore. Energetically facile reaction pathways are identified, which directly involve NaOH and confirm that NaOH may not only play a role as a reactant but also as a catalyst. We demonstrate that collective effects play a decisive role in the mechanism: initiation of the reaction via formation of Q3 defects becomes spontaneous when the Na+ cation is solvated by a sufficient amount of water and subsequent barriers along the desilication pathway are lowered. We show that it is crucial to include a realistic treatment of the hydration environment to capture the processes, which occur inside zeolite pores. This work advances our understanding of a ubiquitous process in heterogeneous catalysts and will help in controlled desilication treatments for zeolite upgrading.
Klasifikace
Druh
Jimp - Článek v periodiku v databázi Web of Science
CEP obor
—
OECD FORD obor
10403 - Physical chemistry
Návaznosti výsledku
Projekt
Výsledek vznikl pri realizaci vícero projektů. Více informací v záložce Projekty.
Návaznosti
P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)
Ostatní
Rok uplatnění
2021
Kód důvěrnosti údajů
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů
Údaje specifické pro druh výsledku
Název periodika
Chemistry of Materials
ISSN
0897-4756
e-ISSN
—
Svazek periodika
33
Číslo periodika v rámci svazku
23
Stát vydavatele periodika
US - Spojené státy americké
Počet stran výsledku
11
Strana od-do
9202-9212
Kód UT WoS článku
000753956100017
EID výsledku v databázi Scopus
2-s2.0-85120782287
Základní informace
Druh výsledku
Jimp - Článek v periodiku v databázi Web of Science
OECD FORD
Physical chemistry
Rok uplatnění
2021