Effect of Alkali-Free Synthesis and Post-Synthetic Treatment on Acid Sites in Beta Zeolites
Beta zeolites with Si/Al around 14 were prepared using three new alkali-free synthesis methods based on the application of amorphous aluminosilicate precursor and calcined in ammonia or air. All samples exhibit structural and textural properties of standard beta zeolite. Comprehensive study by <s...
| Main Authors: | , , , , , , , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2020-07-01
|
| Series: | Molecules |
| Subjects: | |
| Online Access: | https://www.mdpi.com/1420-3049/25/15/3434 |
| _version_ | 1797561076540243968 |
|---|---|
| author | Kinga Mlekodaj Joanna E. Olszowka Venceslava Tokarova Edyta Tabor Ales Kasparek Jana Novakova Gabriela Stavova Olga Gonsiorova Lenka Peliskova Jiri Brus Radim Pilar Petr Klein Jiri Dedecek |
| author_facet | Kinga Mlekodaj Joanna E. Olszowka Venceslava Tokarova Edyta Tabor Ales Kasparek Jana Novakova Gabriela Stavova Olga Gonsiorova Lenka Peliskova Jiri Brus Radim Pilar Petr Klein Jiri Dedecek |
| author_sort | Kinga Mlekodaj |
| collection | DOAJ |
| description | Beta zeolites with Si/Al around 14 were prepared using three new alkali-free synthesis methods based on the application of amorphous aluminosilicate precursor and calcined in ammonia or air. All samples exhibit structural and textural properties of standard beta zeolite. Comprehensive study by <sup>27</sup>Al and <sup>29</sup>Si MAS NMR, together with FTIR adsorption of d<sub>3</sub>-acetonitrile and pyridine were used to characterize the influence of both the synthesis and calcination procedure on the framework Al atoms and related Brønsted and Lewis acid sites. While calcination in ammonia preserves all framework Al atoms, calcination in air results in 15% release of framework Al, but without restrictions of the accessibility of the beta zeolite channel system for bulky pyridine molecules. Terminal (SiO)<sub>3</sub>AlOH groups present in the hydrated zeolites were suggested as a precursor of framework Al-Lewis sites. Surprisingly, the mild dealumination of the air-calcined zeolites result in an increase of the concentration of Brønsted acid sites and a decrease of the total concentration of Lewis sites with the formation of the extra-framework ones. |
| first_indexed | 2024-03-10T18:09:10Z |
| format | Article |
| id | doaj.art-7bb3fe1860294b768c4d2c3092c13749 |
| institution | Directory Open Access Journal |
| issn | 1420-3049 |
| language | English |
| last_indexed | 2024-03-10T18:09:10Z |
| publishDate | 2020-07-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Molecules |
| spelling | doaj.art-7bb3fe1860294b768c4d2c3092c137492023-11-20T08:17:08ZengMDPI AGMolecules1420-30492020-07-012515343410.3390/molecules25153434Effect of Alkali-Free Synthesis and Post-Synthetic Treatment on Acid Sites in Beta ZeolitesKinga Mlekodaj0Joanna E. Olszowka1Venceslava Tokarova2Edyta Tabor3Ales Kasparek4Jana Novakova5Gabriela Stavova6Olga Gonsiorova7Lenka Peliskova8Jiri Brus9Radim Pilar10Petr Klein11Jiri Dedecek12J. Heyrovský Institute of Physical Chemistry, Czech Academic Sciences, Dolejškova 3, 18223 Prague, Czech RepublicJ. Heyrovský Institute of Physical Chemistry, Czech Academic Sciences, Dolejškova 3, 18223 Prague, Czech RepublicUnipetrol Centre for Research and Education a.s., Revoluční 84, 400 01 Ústí nad Labem, Czech RepublicJ. Heyrovský Institute of Physical Chemistry, Czech Academic Sciences, Dolejškova 3, 18223 Prague, Czech RepublicUnipetrol Centre for Research and Education a.s., Revoluční 84, 400 01 Ústí nad Labem, Czech RepublicUnipetrol Centre for Research and Education a.s., Revoluční 84, 400 01 Ústí nad Labem, Czech RepublicUnipetrol Centre for Research and Education a.s., Revoluční 84, 400 01 Ústí nad Labem, Czech RepublicUnipetrol Centre for Research and Education a.s., Revoluční 84, 400 01 Ústí nad Labem, Czech RepublicUnipetrol Centre for Research and Education a.s., Revoluční 84, 400 01 Ústí nad Labem, Czech RepublicInstitute of Macromolecular Chemistry, Czech Academic Sciences, Heyrovského nám. 1888, 16200 Prague, Czech RepublicJ. Heyrovský Institute of Physical Chemistry, Czech Academic Sciences, Dolejškova 3, 18223 Prague, Czech RepublicJ. Heyrovský Institute of Physical Chemistry, Czech Academic Sciences, Dolejškova 3, 18223 Prague, Czech RepublicJ. Heyrovský Institute of Physical Chemistry, Czech Academic Sciences, Dolejškova 3, 18223 Prague, Czech RepublicBeta zeolites with Si/Al around 14 were prepared using three new alkali-free synthesis methods based on the application of amorphous aluminosilicate precursor and calcined in ammonia or air. All samples exhibit structural and textural properties of standard beta zeolite. Comprehensive study by <sup>27</sup>Al and <sup>29</sup>Si MAS NMR, together with FTIR adsorption of d<sub>3</sub>-acetonitrile and pyridine were used to characterize the influence of both the synthesis and calcination procedure on the framework Al atoms and related Brønsted and Lewis acid sites. While calcination in ammonia preserves all framework Al atoms, calcination in air results in 15% release of framework Al, but without restrictions of the accessibility of the beta zeolite channel system for bulky pyridine molecules. Terminal (SiO)<sub>3</sub>AlOH groups present in the hydrated zeolites were suggested as a precursor of framework Al-Lewis sites. Surprisingly, the mild dealumination of the air-calcined zeolites result in an increase of the concentration of Brønsted acid sites and a decrease of the total concentration of Lewis sites with the formation of the extra-framework ones.https://www.mdpi.com/1420-3049/25/15/3434beta zeolitealkali-free synthesisacid sitesframework Al-Lewis sitesextra-framework Al-Lewis sitesBrønsted acid sites |
| spellingShingle | Kinga Mlekodaj Joanna E. Olszowka Venceslava Tokarova Edyta Tabor Ales Kasparek Jana Novakova Gabriela Stavova Olga Gonsiorova Lenka Peliskova Jiri Brus Radim Pilar Petr Klein Jiri Dedecek Effect of Alkali-Free Synthesis and Post-Synthetic Treatment on Acid Sites in Beta Zeolites Molecules beta zeolite alkali-free synthesis acid sites framework Al-Lewis sites extra-framework Al-Lewis sites Brønsted acid sites |
| title | Effect of Alkali-Free Synthesis and Post-Synthetic Treatment on Acid Sites in Beta Zeolites |
| title_full | Effect of Alkali-Free Synthesis and Post-Synthetic Treatment on Acid Sites in Beta Zeolites |
| title_fullStr | Effect of Alkali-Free Synthesis and Post-Synthetic Treatment on Acid Sites in Beta Zeolites |
| title_full_unstemmed | Effect of Alkali-Free Synthesis and Post-Synthetic Treatment on Acid Sites in Beta Zeolites |
| title_short | Effect of Alkali-Free Synthesis and Post-Synthetic Treatment on Acid Sites in Beta Zeolites |
| title_sort | effect of alkali free synthesis and post synthetic treatment on acid sites in beta zeolites |
| topic | beta zeolite alkali-free synthesis acid sites framework Al-Lewis sites extra-framework Al-Lewis sites Brønsted acid sites |
| url | https://www.mdpi.com/1420-3049/25/15/3434 |
| work_keys_str_mv | AT kingamlekodaj effectofalkalifreesynthesisandpostsynthetictreatmentonacidsitesinbetazeolites AT joannaeolszowka effectofalkalifreesynthesisandpostsynthetictreatmentonacidsitesinbetazeolites AT venceslavatokarova effectofalkalifreesynthesisandpostsynthetictreatmentonacidsitesinbetazeolites AT edytatabor effectofalkalifreesynthesisandpostsynthetictreatmentonacidsitesinbetazeolites AT aleskasparek effectofalkalifreesynthesisandpostsynthetictreatmentonacidsitesinbetazeolites AT jananovakova effectofalkalifreesynthesisandpostsynthetictreatmentonacidsitesinbetazeolites AT gabrielastavova effectofalkalifreesynthesisandpostsynthetictreatmentonacidsitesinbetazeolites AT olgagonsiorova effectofalkalifreesynthesisandpostsynthetictreatmentonacidsitesinbetazeolites AT lenkapeliskova effectofalkalifreesynthesisandpostsynthetictreatmentonacidsitesinbetazeolites AT jiribrus effectofalkalifreesynthesisandpostsynthetictreatmentonacidsitesinbetazeolites AT radimpilar effectofalkalifreesynthesisandpostsynthetictreatmentonacidsitesinbetazeolites AT petrklein effectofalkalifreesynthesisandpostsynthetictreatmentonacidsitesinbetazeolites AT jiridedecek effectofalkalifreesynthesisandpostsynthetictreatmentonacidsitesinbetazeolites |