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Functionalization and processing of porous powders into hierarchically porous monoliths
Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry. (Material chemistry)
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Inorganic porous materials are widely used in a number of applications, where is a need to functionalize and produce materials with a multiscale porosity. The first part of the thesis describes how a novel and facile powder processing approach, using pulsed current processing (PCP) or, as it is commonly called, spark plasma sintering (SPS), has been employed to produce mechanically stable, hierarchically porous bodies from different porous powders.

Surfactant-templated mesoporous spheres were PCP-treated to yield meso/macro porous monoliths. The bimodal pore size can be tailored by choice of templating molecules in the aerosol-assisted synthesis process and by the particle size of the spheres. Diatomite powders were used to produce macro/macroporous monoliths. The densification behaviour of this inexpensive and renewable macroporous raw material was evaluated in detail, and an optimum temperature range was identified where the PCP process yields mechanically strong monoliths.

Binder-less, hierarchically porous zeolite monoliths were produced from various zeolite powders, e.g. silicalite-1, ZSM-5 and zeolite Y. Line-broadening analysis of X-ray powder diffraction data by the Rietveld method and electron microscopy showed that the formation of strong interparticle bonds during the PCP process is associated with a local amorphization reaction that is induced by the high contact stress and temperature. Xylene isomerisation studies showed that binder-less ZSM-5 monoliths display a high catalytic selectivity.

Direct (in-situ) nanoparticle functionalization of surfactant templated mesoporous silica particles has also been demonstrated. Pre-synthesized TiO2 nanoparticles were dispersed in a precursor solution, containing surfactant and silica source, and processed in an aerosol-generator to produce spherical nanoparticle-functionalized mesoporous particles.

 

Place, publisher, year, edition, pages
Stockholm: Department of Physical, Inorganic and Structural Chemistry, Stockholm University , 2009. , 79 p.
Keyword [en]
Porous, zeolite, hierarchical, monolith, nanoparticle, functionalization, amorphization, PCP, SPS, pulsed current processing, spark plasma sintering.
National Category
Chemical Sciences
Research subject
Inorganic Chemistry
Identifiers
URN: urn:nbn:se:su:diva-27496ISBN: 978-91-7155-880-0 (print)OAI: oai:DiVA.org:su-27496DiVA: diva2:214496
Public defence
2009-06-08, Magnélisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 12 A, Stockholm, 13:00 (English)
Opponent
Supervisors
Available from: 2009-05-18 Created: 2009-05-05 Last updated: 2010-01-15Bibliographically approved
List of papers
1. Meso/macroporous, mechanically stable silica monoliths of complex shape by controlled fusion of mesoporous spherical particles
Open this publication in new window or tab >>Meso/macroporous, mechanically stable silica monoliths of complex shape by controlled fusion of mesoporous spherical particles
2006 (English)In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 18, 4933-4938 p.Article in journal (Refereed) Published
Identifiers
urn:nbn:se:su:diva-10678 (URN)10.1021/cm061205v (DOI)
Available from: 2008-01-06 Created: 2008-01-06 Last updated: 2017-12-13Bibliographically approved
2. Hierarchically Porous Ceramics from Diatomite Powders by Pulsed Current Processing
Open this publication in new window or tab >>Hierarchically Porous Ceramics from Diatomite Powders by Pulsed Current Processing
2009 (English)In: Journal of The American Ceramic Society, ISSN 0002-7820, E-ISSN 1551-2916, Vol. 92, no 2, 338-343 p.Article in journal (Refereed) Published
Abstract [en]

Hierarchically porous ceramic monoliths have been fabricated by pulsed current processing (PCP) of diatomite powders. The partial sintering behavior of the porous diatomite powders during PCP or spark plasma sintering was evaluated at temperatures between 600 degrees and 850 degrees C. Scanning electron microscopy and mercury porosimetry measurements showed that the PCP method was able to bond the diatomite powder together into relatively strong monoliths without significantly destroying the internal pores of the diatomite powder at a temperature range of 700 degrees-750 degrees C. Little fusion at the particle contact points occurred at temperatures below 650 degrees C while the powder showed partial melting and collapse of both the interparticle pores and the internal structure at temperatures above 800 degrees C.

Keyword
Spark plasma sintering, porous ceramics, diatomite, pulsed current processing
National Category
Natural Sciences
Identifiers
urn:nbn:se:su:diva-32136 (URN)10.1111/j.1551-2916.2008.02882.x (DOI)000263358000007 ()
Available from: 2009-12-04 Created: 2009-12-04 Last updated: 2017-12-12Bibliographically approved
3. Forming strong hierarchically porous zeolite monoliths by PCP-induced local amorphization
Open this publication in new window or tab >>Forming strong hierarchically porous zeolite monoliths by PCP-induced local amorphization
Show others...
(English)Article in journal (Refereed) Submitted
Identifiers
urn:nbn:se:su:diva-27536 (URN)
Available from: 2009-05-06 Created: 2009-05-06 Last updated: 2010-01-14Bibliographically approved
4. An X-ray diffraction and gas adsorption study on the effect of pulsed current processing of ZSM-5 and Y zeolites
Open this publication in new window or tab >>An X-ray diffraction and gas adsorption study on the effect of pulsed current processing of ZSM-5 and Y zeolites
(English)Manuscript (preprint) (Other academic)
National Category
Chemical Sciences
Identifiers
urn:nbn:se:su:diva-27540 (URN)
Available from: 2009-05-06 Created: 2009-05-06 Last updated: 2016-01-29Bibliographically approved
5. Colloidal aspects relating to direct incorporation of TiO2 nanoparticles into mesoporous spheres by an aerosol-assisted process
Open this publication in new window or tab >>Colloidal aspects relating to direct incorporation of TiO2 nanoparticles into mesoporous spheres by an aerosol-assisted process
2008 (English)In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 319, no 1, 144-151 p.Article in journal (Refereed) Published
Abstract [en]

Titania nanoparticles have been incorporated into spherical mesoporous silica powders by an aerosol-assisted synthesis process from both aqueous and ethanol-based precursor dispersions. Transmission electron microscopy (TEM) showed that the titania nanoparticles exist as single particles or small aggregates within the mesoporous carrier particles and analysis of the nitrogen adsorption isotherms proved that the pore blocking of the particles is small. Particle size and zeta potential measurements showed that the addition of tetraethoxysiloxane (TEOS), and also hexadecyl trimethyl ammonium bromide (C16TAB) induced flocculation of the TiO2 nanoparticles. The higher yield and narrower size distribution of the composite powder produced from ethanol-based dispersions compared to the aqueous dispersions could be related to a smaller degree of aggregation, indicated by rheological measurements.

 

Keyword
Colloid, Titania, Mesoporous, Nanoparticle, Aerosol-assisted, Functionalization, Rheology
Identifiers
urn:nbn:se:su:diva-27495 (URN)10.1016/j.jcis.2007.11.013 (DOI)000252750400020 ()
Available from: 2009-05-05 Created: 2009-05-05 Last updated: 2017-12-13Bibliographically approved

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