Synthesis, Characterization, and Catalytic Performance of Highly Dispersed Co-SBA-15
Highly dispersed cobalt on SBA-15 was successfully prepared by a post synthesis grafting of cobalt. Of the cobalt precursors tested, Co(II) acetylacetonate was found to be the best source for high dispersion of cobalt. The Co-SBA-15 catalysts were characterized with different techniques: N2 physisorption, XRD, TPR, TEM, and X-ray adsorption analysis. The mesoporous structure of SBA-15 was retained after cobalt grafting with up to 10 wt % Co loading. There were no large cobalt oxide particles formed, which indicates all the cobalt ions are highly dispersed on the surface and the direct bonding to the silica surfaces results in a high reduction temperature (1123 K) relative to Co oxides. X-ray absorption analysis demonstrates a local structure of Co ions with all Co ions isolated and bonded with oxygen. XANES analysis requires that the local environment for Co ions be that of either a distorted tetrahedral or an octahedral structure and the fitting of EXAFS data further shows a Co-O bond coordination number of 3.58 {+-} 0.48, confirming that the Co is in a distorted tetrahedral environment. The catalytic activity of Co-SBA-15 catalyst was studied for the synthesis of carbon single walled nanotubes (SWNT). The high reduction stability of Co-SBA-15 is presumed to make a favorable catalyst for this high temperature reaction. Raman spectroscopy and TEM photographs show that good quality carbon SWNT was synthesized by Co-SBA-15. Moreover, Co-SBA-15 has a higher yield of carbon SWNT compared with Co-MCM-41 (C16 alkyl template) under the same reaction conditions.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States). National Synchrotron Light Source
- Sponsoring Organization:
- Doe - Office Of Science
- DOE Contract Number:
- DE-AC02-98CH10886
- OSTI ID:
- 980605
- Report Number(s):
- BNL-93523-2010-JA; TRN: US1005528
- Journal Information:
- Journal of Physical Chemistry C, Vol. 113; ISSN 1932-7447
- Country of Publication:
- United States
- Language:
- English
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