Co and Pb are soft oxides, making them useful in partial oxidation catalysis. But it is
difficult to prepare high surface area, nanometer size particles due to the low melting
point of Pb. In the present study, SBA-15 samples are incorporated with Co and/or
Pb at different weight loadings to provide a controlled geometry in nanometer scale
via using direct synthesis method. The characterization of the synthesized samples
was done by XRD, N2 adsorption isotherms, TEM images and XPS analysis. The
increase in the metal loading in SBA-15 causes a decrease in the BET surface area
due to the filling of pores with metal atoms. No characteristic peaks of metal oxide
was observed up to 15 wt %Pb loading into SBA-15 in the large angle XRD pattern
indicating that metal particles are dispersed in the SiO2 structure without
accumulating and forming crystals. However, 20 wt%Pb loaded SBA-15 showed
more appreciable characteristic peaks, indicating appreciable quantities of crystallites
of metal oxide on the surface of silica. The introduction of high amount of cobalt and
lead oxides to SBA-15 resulted in the loss of long range order of pores according to
the low angle XRD patterns. The hexagonal structure of pores of SBA-15 was
v
confirmed by TEM images for all samples. XPS analysis indicated that binding
energies of O 1s and Si 2p are almost similar in Co or Pb loaded samples, while
mixed oxide loaded samples showed slightly higher binding energies which means
the structure grows into a different type.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/12607626/index.pdf |
| Date | 01 September 2006 |
| Creators | Akca, Burcu |
| Contributors | Uner, Deniz |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | M.S. Thesis |
| Format | text/pdf |
| Rights | To liberate the content for public access |
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