Nickel molybdenum oxide catalysts with different chemical compositions have been synthesized
and tested for the oxidative dehydrogenation of n-hexane. The co-precipitation method was used
for the synthesis and several methods were used to characterize these catalysts. These include
inductively-coupled plasma optical emission spectroscopy, Raman spectroscopy, infrared
spectroscopy, energy dispersive X-ray spectroscopy, scanning electron microscopy, temperature
programmed reduction, temperature programmed desorption, X-ray photo-electron spectroscopy
and X-ray diffraction spectroscopy techniques as well as the Brauner-Emmet-Teller technique for
surface area determination. The phase composition of the catalysts was largely dependent on the
chemical composition.
Catalyst testing on n-hexane feed was done with a fixed bed continuous flow reactor and
experiments were performed with feed/air ratios above and below the flammability limit. Varied
reaction conditions were used for the catalytic testing. Prior to the catalytic testing, blank
experiments were performed. Analysis of the products were done both online and offline in
conjunction with gas chromatography employing FID and TCD detectors.
The influence of the catalyst on the conversion of n-hexane and selectivity to dehydrogenation
products is reported. Products observed were the carbon oxides (CO and CO2), isomers of hexene
(1-hexene, 2-hexene and 3-hexene), cyclic C6 products (cyclohexene and benzene), cracked
products: alkanes/alkenes (propane/ene, butane/ene) and oxygenates (ethanal, acetic acid and
propanoic acid). B-NiMoO4 was most selective to the hexenes, especially, 1-hexene and a reaction
scheme is proposed. / Thesis (Ph.D.)-University of KwaZulu-Natal, Westville, 2009.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ukzn/oai:http://researchspace.ukzn.ac.za:10413/8827 |
| Date | January 2009 |
| Creators | Pillay, Bavani. |
| Contributors | Friedrich, Holger Bernhard. |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
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