On the nature of the catalytic activity of silica-based oxide catalysts in the partial oxidation of methane to formaldehyde with O[sub 2]

Journal Article · Mon Aug 01 04:00:00 EDT 1994 · Journal of Catalysis; (United States)

DOI:https://doi.org/10.1006/jcat.1994.1237· OSTI ID:6658573

Parmaliana, A; Arena, F ^[1]; Sokolovskii, V ^[2]; Miceli, D; Giordano, N ^[3]

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1. Universita degli Studi di Messina (Italy)
2. Univ. of Witwatersrand, Johannesburg (South Africa)
3. Istituto CNR-TAE, Messina (Italy)

The partial oxidation of methane to formaldehyde with molecular O[sub 2] has been investigated on various commercial bare SiO[sub 2] samples and silica-supported MoO[sub 3] and V[sub 2]O[sub 5] catalysts at 550-650[degrees]C in batch, pulse, and continuous flow reactors at 1.7 bar. Amongst the different SiO[sub 2] samples, the highest HCHO productivity expressed as space time yield (STY[sub HCHO], g[center dot]kg[sub cat][sup [minus]1][center dot]h[sup [minus]1]) is found with [open quotes]precipitated[close quotes] silica, while [open quotes]fumed[close quotes] SiO[sub 2] results in the least reactive silica. Incorporation of molybdena depresses the STY[sub HCHO] value for the [open quotes]precipitated[close quotes] silica but enhances the STY[sub HCHO] for bare [open quotes]fumed[close quotes] silicas leads to higher STY[sub HCHO] values. On the basis of a series of experiments performed by continuous scanning of the reaction mixture with a quadrupole M.S., the participation of lattice oxygen in the main reaction pathway has been ruled out. The acidic properties of the catalysts have been compared by ZPC and NH[sub 3]-TPD measurements. A straight correlation between the density of reduced sites ([rho], 10[sup 16] S[sub r], g[sub cat][sup [minus]1]), evaluated in steady-state conditions by O[sub 2] chemisorption, and the reaction rate has been disclosed. MoO[sub 3] and V[sub 2]O[sub 5] dopants modify the catalytic properties of SiO[sub 2] by affecting the process of oxygen activation on the catalytic surface. 36 refs., 3 fig., 7 tabs.

• OSTI ID: 6658573
• Journal Information: Journal of Catalysis; (United States), Journal Name: Journal of Catalysis; (United States) Vol. 148:2; 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
CATALYST SUPPORTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CHEMICAL REACTION YIELD
CHEMICAL REACTIONS
CHEMISORPTION
DESORPTION
ELEMENTS
HYDROCARBONS
KINETICS
METHANE
MINERALS
MOLYBDENUM COMPOUNDS
MOLYBDENUM OXIDES
NONMETALS
ORGANIC COMPOUNDS
OXIDATION
OXIDE MINERALS
OXIDES
OXYGEN
OXYGEN COMPOUNDS
REACTION KINETICS
REFRACTORY METAL COMPOUNDS
SEPARATION PROCESSES
SILICA
SILICON COMPOUNDS
SILICON OXIDES
SORPTION
TEMPERATURE DEPENDENCE
TRANSITION ELEMENT COMPOUNDS
VANADIUM COMPOUNDS
VANADIUM OXIDES
YIELDS