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De-agglomeration of IZM-2 zeolite crystals by post-synthetic treatment
Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
Vise andre og tillknytning
Rekke forfattare: 72016 (engelsk)Inngår i: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 225, s. 185-191Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Highly intergrown nanocrystals are commonly observed in zeolite samples, and the densely packed agglomerates may result in small secondary porosity, which restricts the advantage of hierarchical structures. In this work we take IZM-2 zeolite as an example to demonstrate a post-treatment method with diluted hydrofluoric acid solution, which de-agglomerates intergrown zeolite nanocrystals and improves the secondary porosity. The treated samples preserve high crystallinity, similar framework composition and distinctively higher external surface area compared to the agglomerated ones. The results show that this treatment is an effective method for de-agglomeration of intergrown nanocrystals without affecting the original framework.

sted, utgiver, år, opplag, sider
2016. Vol. 225, s. 185-191
Emneord [en]
Zeolite, Nanocrystals, De-agglomeration, Post treatment, Hierarchical porosity
HSV kategori
Forskningsprogram
materialkemi
Identifikatorer
URN: urn:nbn:se:su:diva-130161DOI: 10.1016/j.micromeso.2015.12.021ISI: 000373421700020OAI: oai:DiVA.org:su-130161DiVA, id: diva2:927594
Tilgjengelig fra: 2016-05-12 Laget: 2016-05-09 Sist oppdatert: 2017-05-11bibliografisk kontrollert
Inngår i avhandling
1. Modification of zeolites and synthesis of SAPO-templated carbon
Åpne denne publikasjonen i ny fane eller vindu >>Modification of zeolites and synthesis of SAPO-templated carbon
2017 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

Zeolites are crystalline aluminosilicates with diverse structures and uniform porosities. They are widely used as catalysts, adsorbents and ion-exchangers in industry. Direct or post modifications optimize the performance of zeolites for different applications. In this thesis, IZM-2 and TON-type zeolites were synthesized, modified and studied. In addition, FAU-type zeolite and silicoaluminophosphate (SAPO) molecular sieves were applied as templates for the preparation of microporous carbons.

In the first part of this thesis, the IZM-2 zeolite with an unknown structure was synthesized. We focused on the increasing the secondary porosity and the varied framework compositions upon post modifications.

The structure determination of this IZM-2 zeolite was hindered by the small size of crystals. In the second part of this thesis, the synthesis composition was directly modified in order to increase the crystal sizes. IZM-2 crystals were enlarged by excluding the aluminium atoms from the framework. The micropores of the obtained pure-silica polymorphs were activated by ion-exchanging alkali-metal ions with protons.

Typically, TON-type zeolites that are synthesized at hydrothermal conditions under stirring have needle-shaped crystals. In the third part of this thesis, snowflake-shaped aggregates were produced by using static hydrothermal conditions for the synthesis of TON-type zeolites. The effects of synthesis parameters on the growth and morphology of crystals were discussed in detail.

In the last part of this thesis, microporous carbons with a structural regularity were prepared by chemical vapour deposition (CVD) of propylene using a silicoaluminophosphate (SAPO-37) template. Compared to the conventional zeolite templates, the SAPO template could be removed under mild conditions, without using hydrofluoric acid, and the generated carbons had a large specific surface area and a high fraction of ultrasmall micropores.

sted, utgiver, år, opplag, sider
Stockholm: Department of Materials and Environmental Chemistry, Stockholm University, 2017. s. 71
Emneord
microporous material, zeolite, SAPO templated carbon, hydrothermal synthesis, CVD, post modification, direct modification, snowflake
HSV kategori
Forskningsprogram
materialkemi
Identifikatorer
urn:nbn:se:su:diva-141834 (URN)978-91-7649-831-6 (ISBN)978-91-7649-832-3 (ISBN)
Disputas
2017-06-13, Magnélisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 16 B, Stockholm, 13:00 (engelsk)
Opponent
Veileder
Merknad

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.

Tilgjengelig fra: 2017-05-19 Laget: 2017-04-19 Sist oppdatert: 2017-05-22bibliografisk kontrollert

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