Modification of zeolites and synthesis of SAPO-templated carbon
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 zeo...
| Main Author: | |
|---|---|
| Format: | Doctoral Thesis |
| Language: | English |
| Published: |
Stockholms universitet, Institutionen för material- och miljökemi (MMK)
2017
|
| Subjects: | |
| Online Access: | http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-141834 http://nbn-resolving.de/urn:isbn:978-91-7649-831-6 http://nbn-resolving.de/urn:isbn:978-91-7649-832-3 |
| Summary: | 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. === <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.</p> |
|---|