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What are the limits of Co and/or Pb loading on SBA-15 structures?

Burcu Akca 1Aysen Yilmaz Mukaddes Can 1Deniz Uner 1

1. Middle East Technical University (METU), Inonu Bulvari, Ankara 06531, Turkey


SBA-15( Santa Barbara amorphous-15) is one of the types of mesoporous silicas with highly ordered hexagonal mesochannels, large pores, thick walls and high thermal stability which make it a promising catalyst support. In this study, SBA-15 samples are modified by doping of Co and/or Pb with different weight loadings. Pure and Co and/or Pb incorporated SBA-15 were prepared by direct synthesis. The synthesized samples were characterized by powder X-ray diffraction, N2 adsorption isotherms and TEM images. The BET surface area of pure SBA-15 mesoporous structure is observed to be slowly decreasing by the addition of metal oxides. No characteristic peaks of metal oxide are observed in the large angle XRD pattern by the loading of 5, 10, 15 wt %Pb into SBA-15 indicating metal particles are dispersed in the SiO2 structure without accumulating and forming a crystal in a certain part of the framework. But loading of 20 wt%Pb in SBA-15 showed more appreciable characteristic peaks, indicating small quantity of crystallites of metal oxide existing on the surface of silica. The introduction of high amount of cobalt and lead oxides into SBA-15 resulted in the long range order according to the low angle XRD patterns. The hexagonal structure of pure SBA-15 and 1-D channel structure in hexagonal type can be observed in TEM images. When SBA-15 structures were overloaded with Co, it is observed that Co extends outside the structure.The performance tests of the materials as methane partial oxidation catalyst for hydrogen generation is in progress.


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Related papers

Presentation: Poster at E-MRS Fall Meeting 2006, Symposium C, by Mukaddes Can
See On-line Journal of E-MRS Fall Meeting 2006

Submitted: 2006-05-15 13:38
Revised:   2009-06-07 00:44