Crack formation in α-alumina supported MFI zeolite membranes studied by in situ high temperature synchrotron powder diffraction

Validerad; 2007; 20070411 (chan)
Cracks are frequently formed in α-alumina supported MFI membranes during calcination. To better understand crack formation, in situ powder diffraction data were collected during calcination of a type of MFI membrane (ca. 1800 nm thick) which is known to crack reproducibly. In addition, data for MFI powder and a blank support were also collected. Both a synchrotron radiation facility and an in-house instrument were used. The unit cell parameters were determined with the Rietveld method, and the strain in the direction perpendicular to the film surface was calculated for the film as well as for the support. The microstrain in the support was also estimated. Based on the results obtained here, a model for crack formation in this type of MFI membrane was proposed. The lack of cracks in other types of MFI membranes (ca. 500 nm) prepared in our laboratory is also explained by the model. In thicker MFI films, the crystals are well intergrown. During heating, the MFI crystals contract and the α-alumina support expands. Consequently, a thermal stress develops in the composite which eventually leads to formation of cracks in the film and structural defects in the support. In thinner films, the crystals are less well intergrown and the thermal expansion mismatch leads to opening of grain boundaries rather than cracks.

TEKNIK OCH TEKNOLOGIER Kemiteknik Kemiska processer hsv//swe
ENGINEERING AND TECHNOLOGY Chemical Engineering Chemical Process Engineering hsv//eng
MFI zeolite membrane
In situ study
Synchrotron powder diffraction
Crack formation
Rietveld method
Chemical Technology
Kemisk teknologi

Andersson, CharlotteLuleå tekniska universitet,Institutionen för samhällsbyggnad och naturresurser(Swepub:ltu)chan (author)
Jareman, FredrikLuleå tekniska universitet (author)
Hedlund, JonasLuleå tekniska universitet,Industriell miljö- och processteknik(Swepub:ltu)johe (author)
Gualtieri, Alessandro F.Dipartimento di Scienze della Terra, Università di Modena e Reggio Emilia, Modena, Italy (author)
Leoni, MatteoDipartimento di Ingegneria dei Materiali, Università di Trento, Mesiano, Italy (author)
Meneghini, CarloDipartimento di Fisica ‘E. Amaldi’ Università di Roma Tre, Roma, Italy (author)
Luleå tekniska universitetInstitutionen för samhällsbyggnad och naturresurser (creator_code:org_t)

By the author/editor: Gualtieri, Magda ...; Andersson, Charl ...; Jareman, Fredrik; Hedlund, Jonas; Gualtieri, Aless ...; Leoni, Matteo; show more...; Meneghini, Carlo; show less...

About the subject

ENGINEERING AND TECHNOLOGY: ENGINEERING AND ...; and Chemical Enginee ...; and Chemical Process ...

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