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Processing and performance of zeolites for efficient carbon dioxide separation
Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). (Lennart Bergström)
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

We have structured zeolites from powders of zeolite 13X and 4A into hierarchically porous monoliths for efficient carbon dioxide capture by tailoring the pore dimensions to facilitate rapid gas uptake and release. Freeze-casting was used for the first time to shape adsorbents into a lamellar structure. Lamellar walls with thicknesses and spacing in the range of 10 µm were found to be the best combination between rapid gas transport and a short diffusion distance in the zeolite-containing walls for rapid carbon dioxide uptake and release.

Compressive strength measurements of the freeze-cast zeolite-based monoliths showed that monoliths with small pores, thin walls and a lot of interconnectivity between the walls were stronger than monoliths with large pores and thick walls. Image analysis of the structures together with modelling of the deformation behavior suggests that the failure mechanism of freeze-cast monoliths is dominated by buckling.

Binder-free zeolite Y and ZSM-5 -based monoliths were produced by pulsed current processing (PCP) into strong, hierarchically porous monoliths with minimal loss of crystallinity. Ranges for the maximum PCP processing temperatures for the zeolites with different aluminium contents were identified by powder x-ray diffraction (PXRD) with full-profile fitting analysis.

Matching the thermal expansion behavior of the supports with the zeolite film is important to minimize the risk of thermally induced cracking of zeolite membranes. Zeolite supports with a macroporous structure was prepared by PCP and the thermal expansion coefficient was determined by PXRD and compared to traditional alumina substrates. It was found that the slightly negative thermal expansion coefficient of the zeolite supports matched the thermal expansion of the zeolite films very well, whereas the alumina support would induce large stresses upon fluctuating temperatures.

Methylcellulose-directed synthesis of zeolite 4A produced nano-sized crystals with a narrow size distribution, which could be tuned by adjusting the methylcellulose content. The crystallinity of the synthesized 4A was controlled by PXRD and found to be very high, and the gas uptake capability performed well in comparison with available micron-sized zeolites.

Place, publisher, year, edition, pages
Stockholm: Department of Materials and Environmental Chemistry, Stockholm University , 2015. , 69 p.
National Category
Materials Chemistry
Research subject
Materials Chemistry
Identifiers
URN: urn:nbn:se:su:diva-114160ISBN: 978-91-7649-107-2 (print)OAI: oai:DiVA.org:su-114160DiVA: diva2:790063
Public defence
2015-03-27, Magnéli Hall, Arrhenius Laboratory, Svante Arrhenius Väg 16 B, Stockholm, 13:00 (English)
Opponent
Supervisors
Funder
Berzelii Centre EXSELENT
Note

At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 2: Submitted.

Available from: 2015-03-05 Created: 2015-02-23 Last updated: 2015-12-02Bibliographically approved
List of papers
1. Laminated Adsorbents with Very Rapid CO2 Uptake by Freeze-Casting of Zeolites
Open this publication in new window or tab >>Laminated Adsorbents with Very Rapid CO2 Uptake by Freeze-Casting of Zeolites
2013 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 5, no 7, 2669-2676 p.Article in journal (Refereed) Published
Abstract [en]

Structured zeolite 13X monoliths with a laminated structure and hierarchical macro-/microporosity were prepared by freeze-casting aqueous suspensions of zeolite 13X powder, bentonite, and polyethylene glycol. Colloidally stable suspensions with a low viscosity at both room temperature and near freezing could be prepared at alkaline conditions where both the zeolite 13X powder and bentonite carry a negative surface charge. Slow directional freezing of the suspensions led to the formation of well-defined and thin lamellar pores and pore walls while fast freezing resulted in more cylindrical pores. The wall thickness, which varied between 8 and 35 mu m, increased with increasing solids loading of the suspension. Thermal treatment at 1053 K of the freeze-cast bodies containing between 9 and 17 wt % bentonite resulted in mechanically stable zeolite 13X monoliths. The monoliths displayed a carbon dioxide uptake capacity of 4-5 mmol/g and an uptake kinetics characterized by a very fast initial uptake where more than 50% of the maximum uptake was reached within 15 s. Freeze-cast laminated zeolite monoliths could be used to improve the volumetric efficiency and reduce the cycle time, of importance in, for example, biogas upgrading and CO2 separation from flue gas.

Keyword
freeze-casting, zeolite 13X, shaping, structured, laminate, adsorbent, hierarchical, carbon dioxide, CCS, gas separation, uptake kinetics
National Category
Nano Technology Materials Engineering
Research subject
Materials Chemistry
Identifiers
urn:nbn:se:su:diva-90187 (URN)10.1021/am400122r (DOI)000317549100051 ()
Note

AuthorCount:4;

Available from: 2013-05-28 Created: 2013-05-28 Last updated: 2017-12-06Bibliographically approved
2. Mechanical performance and CO2 uptake of ion-exchanged zeolite A structured by freeze-casting
Open this publication in new window or tab >>Mechanical performance and CO2 uptake of ion-exchanged zeolite A structured by freeze-casting
Show others...
2015 (English)In: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 35, no 9, 2607-2618 p.Article in journal (Refereed) Published
Abstract [en]

Zeolite 4A has been freeze-cast into highly porous monoliths with a cylindrical shape. The brittle monoliths, with lamellar or columnar pores and wall thicknesses between 8 and 35 mu m, show a compressive mechanical response along the main pore axis that could be modeled by a buckling behavior. The failure strength is proportional to the density and the amount of transverse bridging across lamella, which was shown to be related to the pore cross-sectional aspect ratio. Monoliths with highly anisotropic pores with a cross-sectional aspect ratio higher than 3 yielded sequentially from the top surface, whereas monoliths with a pore aspect ratio lower than 3 were found to delaminate into longitudinal splinters. The freeze-cast monoliths show a sharp gas breakthrough front with a 1:9 mixture of CO2 and N-2, indicating rapid uptake kinetics of the lamellar structures.

Keyword
Freeze-casting, Porous ceramics, Mechanical strength, Zeolite A, Laminate
National Category
Materials Engineering Chemical Sciences
Research subject
Materials Chemistry
Identifiers
urn:nbn:se:su:diva-118327 (URN)10.1016/j.jeurceramsoc.2015.03.001 (DOI)000354505300020 ()
Available from: 2015-06-18 Created: 2015-06-15 Last updated: 2017-12-04Bibliographically approved
3. The effect of temperature on the pulsed current processing behaviour and structural characteristics of porous ZSM-5 and zeolite Y monoliths
Open this publication in new window or tab >>The effect of temperature on the pulsed current processing behaviour and structural characteristics of porous ZSM-5 and zeolite Y monoliths
2010 (English)In: Journal of the European Ceramic Society, ISSN 0955-2219, Vol. 30, no 14, 2977-2983 p.Article in journal (Refereed) Published
Abstract [en]

Hierachically porous monoliths of ZSM-5 and Y zeolites have been prepared by pulsed current processing (PCP). The densification behaviour andstructural characteristics during rapid thermal treatment of the zeolites have been determined and related to the influence of the Si:Al ratio on thethermal stability of the zeolites. Monoliths of macroscopic shape can be prepared with an insignificant loss of surface area and micropore volumewhen the PCP-treatment was performed at temperatures below a critical maximum PCP temperature (TPCP). Full-profile fittings of the powderX-ray diffraction patterns showed that the lattice strain of zeolite Y increases rapidly above the critical TPCP while the ZSM-5 zeolites undergo aphase transition from orthorhombic to monoclinic. The use of a novel ceramic processing route for the production of the zeolite monoliths that donot significantly influence the structural characteristics and surface area of the starting materials has a potential to be of importance in catalysisand gas separation applications.

Keyword
Pulsed current processing; Porosity; X-ray methods
National Category
Inorganic Chemistry
Research subject
Materials Chemistry
Identifiers
urn:nbn:se:su:diva-46202 (URN)10.1016/j.jeurceramsoc.2010.02.007 (DOI)
Projects
Berzelii centre EXSELENT
Funder
Swedish Research Council
Available from: 2010-11-26 Created: 2010-11-23 Last updated: 2015-03-02Bibliographically approved
4. Hierarchically porous binder-free silicalite-1 discs: a novel support for all-zeolite membranes
Open this publication in new window or tab >>Hierarchically porous binder-free silicalite-1 discs: a novel support for all-zeolite membranes
Show others...
2011 (English)In: Journal of Materials Chemistry, ISSN 0959-9428, E-ISSN 1364-5501, Vol. 21, no 24, 8822-8828 p.Article in journal (Refereed) Published
Abstract [en]

Thermal expansion mismatch between the zeolite film and the support is an important cause for the formation of defects and cracks during the fabrication and use of zeolite membranes. We have studied how silicalite-1 discs with a permeability comparable to commercially available alumina supports can be produced by pulsed current processing (PCP) as a novel substrate for all-zeolite membranes. Hierarchically porous and mechanically strong membrane supports where the surface area and crystallography of the silicalite-1 particles were maintained could be obtained by carefully controlling the thermal treatment during PCP consolidation. In situ X-ray diffraction and dilatometry showed that the coefficient of thermal expansion (CTE) of the silicalite-1 substrate was negative in the temperature range 200-800 degrees C while the commonly used alumina substrate displayed a positive CTE. The critical temperature variation, Delta T, and thicknesses for crack-free supported zeolite films with a negative CTE were estimated using a fracture energy model. Zeolite films with a thickness of 1 mu m can only sustain a relatively modest Delta T of 100 degrees when supported onto alumina substrates while the all-zeolite membranes can support temperature variations above 500 degrees.

National Category
Materials Chemistry
Research subject
Materials Chemistry
Identifiers
urn:nbn:se:su:diva-66641 (URN)10.1039/c1jm10584a (DOI)000291352900049 ()
Note

authorCount :5

Available from: 2011-12-20 Created: 2011-12-20 Last updated: 2017-12-08Bibliographically approved
5. Methylcellulose-Directed Synthesis of Nanocrystalline Zeolite NaA with High CO2 Uptake
Open this publication in new window or tab >>Methylcellulose-Directed Synthesis of Nanocrystalline Zeolite NaA with High CO2 Uptake
2014 (English)In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 7, no 8, 5507-5519 p.Article in journal (Refereed) Published
Abstract [en]

Zeolite NaA nanocrystals with a narrow particle size distribution were prepared by template-free hydrothermal synthesis in thermo-reversible methylcellulose gels. The effects of the amount of methylcellulose, crystallization time and hydrothermal treatment temperature on the crystallinity and particle size distribution of the zeolite NaA nanocrystals were investigated. We found that the thermogelation of methylcellulose in the alkaline Na2O-SiO2-Al2O3-H2O system played an important role in controlling the particle size. The synthesized zeolite nanocrystals are highly crystalline, as demonstrated by X-ray diffraction (XRD), and scanning electron microscopy (SEM) shows that the nanocrystals can also display a well-defined facetted morphology. Gas adsorption studies on the synthesized nanocrystalline zeolite NaA showed that nanocrystals with a size of 100 nm displayed a high CO2 uptake capacity (4.9 mmol/g at 293 K at 100 kPa) and a relatively rapid uptake rate compared to commercially available, micron-sized particles. Low-cost nanosized zeolite adsorbents with a high and rapid uptake are important for large scale gas separation processes, e.g., carbon capture from flue gas.

Keyword
zeolite NaA, nanocrystals, hydrothermal synthesis, carbon dioxide adsorption
National Category
Materials Chemistry
Research subject
Materials Chemistry
Identifiers
urn:nbn:se:su:diva-107809 (URN)10.3390/ma7085507 (DOI)000341210400006 ()
Note

AuthorCount:4;

Available from: 2014-10-05 Created: 2014-09-29 Last updated: 2017-12-05Bibliographically approved

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