Methane oxidative coupling II. A study of lithium-titania-catalyzed reactions of methane

Journal Article · Fri Sep 01 04:00:00 EDT 1989 · Journal of Catalysis; (USA)

DOI:https://doi.org/10.1016/0021-9517(89)90143-7· OSTI ID:6957808

Lane, G S; Miro, E; Wolf, E E ^[1]

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1. Univ. of Notre Dame, IN (USA)

Methane conversion to higher hydrocarbons via oxidative coupling was studied on a series of lithium-doped titania catalysts by cofeeding methane and oxygen. The degree of lithium promotion was studied by varying the lithium loading from 0 to 31.7 wt% lithium on the rutile crystal structure of titania. Catalytic results indicate that lithium-doped titania catalysts are effective for oxidative coupling of methane with hydrocarbon product selectivities ranging from 20 to 85%. Increasing the lithium loading reduces the combustion activity of the catalyst, improves hydrocarbon selectivity, and increases space-time yields. Product yield reached a maximum for the 16.2-wt% loading; this catalyst had methane conversions of ca. 15% with hydrocarbon selectivities of ca. 75%. The 16.2-wt% lithium-titania catalyst was studied under various operating conditions and compared favorably with other catalytic results that have been reported. The observed activation energy of the 16.2% lithium-titania catalyst was dependent on the reactant partial pressure and ranged from 25.6 to 37.6 kcal/mole. X-ray diffraction, X-ray photoelectron spectroscopy, infrared analysis, and differential thermal analysis results of the catalysts indicate that increasing the degree of lithium promotion lowers the surface area and the surface concentration of oxygen, and creates different phases at elevated temperatures. Routes for surface-catalyzed reactions coupled with gas-phase reactions were studied by transient pulse and step-change experiments. The transient experiments suggest that adsorbed oxygen is responsible for the C{sub 2} hydrocarbon activity of the lithium-titania catalyst and that lattice oxygen activates methane nonselectively.

• OSTI ID: 6957808
• Journal Information: Journal of Catalysis; (USA), Journal Name: Journal of Catalysis; (USA) Vol. 119:1; ISSN 0021-9517; ISSN JCTLA
• Country of Publication: United States
• Language: English

Related Subjects

03 NATURAL GAS
030300* -- Natural Gas-- Drilling
Production
& Processing
ACTIVATION ENERGY
ALKALI METALS
ALKANES
CATALYTIC EFFECTS
CATALYTIC REFORMING
CHALCOGENIDES
CHEMICAL REACTIONS
COHERENT SCATTERING
CRYSTAL STRUCTURE
DIFFERENTIAL THERMAL ANALYSIS
DIFFRACTION
DOPED MATERIALS
ELECTRON SPECTROSCOPY
ELEMENTS
ENERGY
HYDROCARBONS
INFRARED SPECTRA
LITHIUM
LOADING RATE
MATERIALS
METALS
METHANE
NONMETALS
ORGANIC COMPOUNDS
OXIDATION
OXIDES
OXYGEN
OXYGEN COMPOUNDS
PHOTOELECTRON SPECTROSCOPY
PROMOTERS
REFORMER PROCESSES
SCATTERING
SPECTRA
SPECTROSCOPY
SURFACE AREA
SURFACE PROPERTIES
SYNTHESIS
THERMAL ANALYSIS
TITANIUM COMPOUNDS
TITANIUM OXIDES
TRANSITION ELEMENT COMPOUNDS
X-RAY DIFFRACTION
X-RAY SPECTROSCOPY