A basic approach to evaluate methane partial oxidation catalysts

Journal Article · Wed Sep 01 04:00:00 EDT 1993 · Journal of Catalysis; (United States)

DOI:https://doi.org/10.1006/jcat.1993.1271· OSTI ID:5771923

Parmaliana, A ^[1]; Frusteri, F; Mezzapica, A; Micelli, D; Giordano, N ^[2]; Scurrell, M S ^[3]

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1. Universita degli Studi di Messina (Italy)
2. Instituto CNR-TAE, Messina (Italy)
3. CSIR, Pretoria (South Africa)

The partial oxidation of methane to formaldehyde by molecular oxygen on silica and silica-supported oxide catalysts has been investigated at a pressure of 1.7 bar in the temperature range 520-650[degrees]C by using a batch reactor with external recycle. The effects of reactor diameter, recycle flow rate, catalyst weight, and methane-to-oxygen ratio on the catalyst activity have been outlined. By performing several blank tests with an empty and a quartz-filled reactor, it has been demonstrated that the gas-phase reaction does not affect the catalytic pathways. Reasons for controversial results reported previously are discussed. They lie in the lack of an adequate experimental approach and in the generally adopted rule to evaluate the catalytic activity at differential conditions in order to push the HCHO selectivity to high values. The approach presented here allows one to evaluate the catalytic activity by performing tests at quasi-zero conversion per mass but at a finite extent of conversion. The need to express the catalytic activity as space time yield (STY) to HCHO (g[center dot]kg[sub cat][sup [minus]1][center dot]h[sup [minus]1]) is presented. The reactivities of various commercial SiO[sub 2] samples obtained by precipitation, sol-gel, and pyrolysis methods have been determined. The fact that the nature and source of silica has a marked effect on STY, previously observed for reaction at 520[degrees]C, has been confirmed for operation at 550-650[degrees]C. Highest STYs are found with precipitated silica samples. In fact, at 650[degrees]C with such precipitated SiO[sub 2] a STY to HCHO of 303 g[center dot] kg[sub cat][sup [minus]1] [center dot] H[sup [minus]1] has been obtained. Incorporation of molybdena depresses the STY value for the precipitated silica but enhances the STY of bare fumed silica. In contrast, addition of vanadia to either precipitated or fumed silicas leads to higher STY values. 29 refs., 6 figs., 8 tabs.

• OSTI ID: 5771923
• Journal Information: Journal of Catalysis; (United States), Journal Name: Journal of Catalysis; (United States) Vol. 143:1; ISSN 0021-9517; ISSN JCTLA5
• Country of Publication: United States
• Language: English

Related Subjects

10 SYNTHETIC FUELS
100200 -- Synthetic Fuels-- Production-- (1990-)
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ALKANES
CATALYSIS
CATALYST SUPPORTS
CATALYSTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL REACTION YIELD
CHEMICAL REACTIONS
HETEROGENEOUS CATALYSIS
HYDROCARBONS
METHANE
MINERALS
MOLYBDENUM COMPOUNDS
MOLYBDENUM OXIDES
ORGANIC COMPOUNDS
OXIDATION
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
REFRACTORY METAL COMPOUNDS
SILICA
SILICON COMPOUNDS
SILICON OXIDES
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE
TEMPERATURE RANGE 0400-1000 K
TRANSITION ELEMENT COMPOUNDS
VANADIUM COMPOUNDS
VANADIUM OXIDES
YIELDS