Oxidative coupling of methane to higher hydrocarbons and carbon monoxide oxidation over titania-based catalysts

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1988

OSTI ID:7080095

Lane, G S

Oxidative coupling of methane was studied over several titania-based catalysts. The trend dictated by the gas phase kinetic shows that the hydrocarbon selectivity falls as methane conversion increases. Specifically, at methane conversions of 2%, the hydrocarbon selectivity was around 65%, but when methane conversions were increased to 32%, the hydrocarbon selectivity decreased to 29%. A reaction pathway for gas phase oxidative coupling has been considered and compared to proposed catalytic pathways. Catalytic results indicate lithium-doped titania catalysts are effective for oxidative coupling. Increasing the lithium loading reduces the combustion capacity of the catalyst,lowers methane conversion, and increases hydrocarbon selectivity. A series of titanate catalysts was also studied for their oxidative coupling activity. The lanthanum-titanate catalyst had the best hydrocarbon yields of the titanate catalysts and was more active at lower temperatures than any other catalysts studied. Catalytic oxidation of CO was investigated on Pt/TiO{sub 2} catalysts to study the influence of SMSI effects and of using different titania crystal structures. Catalysts, prepared using rutile and anatase titania, were characterized by chemisorption, x-ray diffraction, and x-ray photoelectron spectroscopy. Effects of reduction temperature and of support material on CO oxidation activity were compared through temperature programmed reaction experiments. Catalysts reduced at 200 C show slightly higher activity and lower ignition temperatures than those reduced at 500 C. Rutile-supported catalysts show much higher CO oxidation activity with lower ignition temperatures. A morphological model of metal-support interactions involving oxygen transfer from the support is proposed to coexist with the Langmuir-Hinshelwood mechanism.

• Research Organization: Notre Dame Univ., IN (USA)
• OSTI ID: 7080095
• Country of Publication: United States
• Language: English

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CRYSTAL STRUCTURE
DIFFRACTION
ELECTRON SPECTROSCOPY
ELEMENTS
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HYDROGEN
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MATHEMATICAL MODELS
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TRANSITION ELEMENT COMPOUNDS
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X-RAY DIFFRACTION
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YIELDS