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Zeolites - a high resolution electron microscopy study

Thesis/Dissertation:

Abstract

High resolution transmission electron microscopy (HRTEM) has been used to investigate a number of zeolites (EMT, FAU, LTL, MFI and MOR) and a member of the mesoporous M41S family. The electron optical artefact, manifested as a dark spot in the projected centre of the large zeolite channels, caused by insufficient transfer of certain reflections in the objective lens has been explained. The artefact severely hinders observation of materials confined in the zeolite channels and cavities. It is shown how to circumvent the artefact problem and how to image confined materials in spite of disturbance caused by the artefact. Image processing by means of a Wiener filter has been applied for removal of the artefact. The detailed surface structure of FAU has been investigated. Comparison of experimental micrographs with images simulated using different surface models indicates that the surface can be terminated in different ways depending on synthesis methods. The dealuminated form of FAU (USY) is covered by an amorphous region. Platinum incorporated in FAU has a preponderance to aggregate in the (111) twin planes, probably due to a local difference in cage structure with more spacious cages. It is shown that platinum is intra-zeolitic as opposed to being located on  More>>
Authors:
Publication Date:
Oct 01, 1994
Product Type:
Thesis/Dissertation
Report Number:
LUTKDH-TKOO-1015
Reference Number:
SCA: 360202; PA: AIX-26:009965; EDB-95:029525; SN: 95001323480
Resource Relation:
Other Information: TH: Doctoral Diss. (TeknD).; PBD: Oct 1994
Subject:
36 MATERIALS SCIENCE; ZEOLITES; CRYSTAL STRUCTURE; SURFACE PROPERTIES; IMAGE PROCESSING; INCLUSIONS; PLATINUM; TRANSMISSION ELECTRON MICROSCOPY; 360202; STRUCTURE AND PHASE STUDIES
OSTI ID:
10111290
Research Organizations:
Lund Univ. (Sweden). Dept. of Inorganic Chemistry 2
Country of Origin:
Sweden
Language:
English
Other Identifying Numbers:
Other: ON: DE95612250; TRN: SE9400202009965
Availability:
OSTI; NTIS; INIS
Submitting Site:
SWDN
Size:
48 p.
Announcement Date:
Jun 30, 2005

Thesis/Dissertation:

Citation Formats

Alfredsson, V. Zeolites - a high resolution electron microscopy study. Sweden: N. p., 1994. Web.
Alfredsson, V. Zeolites - a high resolution electron microscopy study. Sweden.
Alfredsson, V. 1994. "Zeolites - a high resolution electron microscopy study." Sweden.
@misc{etde_10111290,
title = {Zeolites - a high resolution electron microscopy study}
author = {Alfredsson, V}
abstractNote = {High resolution transmission electron microscopy (HRTEM) has been used to investigate a number of zeolites (EMT, FAU, LTL, MFI and MOR) and a member of the mesoporous M41S family. The electron optical artefact, manifested as a dark spot in the projected centre of the large zeolite channels, caused by insufficient transfer of certain reflections in the objective lens has been explained. The artefact severely hinders observation of materials confined in the zeolite channels and cavities. It is shown how to circumvent the artefact problem and how to image confined materials in spite of disturbance caused by the artefact. Image processing by means of a Wiener filter has been applied for removal of the artefact. The detailed surface structure of FAU has been investigated. Comparison of experimental micrographs with images simulated using different surface models indicates that the surface can be terminated in different ways depending on synthesis methods. The dealuminated form of FAU (USY) is covered by an amorphous region. Platinum incorporated in FAU has a preponderance to aggregate in the (111) twin planes, probably due to a local difference in cage structure with more spacious cages. It is shown that platinum is intra-zeolitic as opposed to being located on the external surface of the zeolite crystal. This could be deduced from tomography of ultra-thin sections among observations. HRTEM studies of the mesoporous MCM-41 show that the pores have a hexagonal shape and also supports the mechanistic model proposed which involves a cooperative formation of a mesophase including the silicate species as well as the surfactant. 66 refs, 24 figs.}
place = {Sweden}
year = {1994}
month = {Oct}
}