Flame generation of ceramic oxides
- John Hopkins Univ., Baltimore, MD (United States)
Large quantities of TiO{sub 2}, SiO{sub 2}, and mixed TiO{sub 2}-SiO{sub 2} powders are produced annually by combustion of their chloride precursors for use as catalysts and as paint opacifiers. We have studied the formation of flame synthesized oxides using a counterflow diffusion flame burner. It has enabled us to obtain desired morphologies and crystalline structures by varying process variables such as flame temperature and precursor concentration ratio, and by selecting the appropriate feed stream. For example, over the ranges of TiCl{sub 4} (the TiO{sub 2} precursor) concentrations tested, feeding it only into the oxidizer stream yields mainly anatase TiO{sub 2} powders, while feeding only into the fuel stream yields mainly rutile TiO{sub 2} powders. By adding TiCl{sub 4} and SiCl{sub 4} simultaneously to the same flame and choosing conditions such that the TiO{sub 2} condenses before the SiO{sub 2}, we obtained SiO{sub 2} attached to, or coated onto, TiO{sub 2} particles in a single step process. Oxide particles produced in the counterflow diffusion flame burner are in the 10 to 100 manometer range. Their high surface area makes them potentially useful as catalysts. V{sub 2}O{sub 5}-TiO{sub 2} and V{sub 2}O{sub 5}-Al{sub 2}O{sub 3} are well-known catalysts for the selective oxidation of o-xylene to phthalic anhydride, and V-P-O oxides are widely used catalysts for the selective oxidation of butene and n-butane to maleic anhydride. Several V{sub 2}O{sub 5}-based mixed oxide powders were produced in the burner. 21 refs.
- OSTI ID:
- 430491
- Report Number(s):
- CONF-960730--
- Country of Publication:
- United States
- Language:
- English
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