The oxidation of methane on heteropolyoxometalates IV. Properties of the silica-supported salts of 12-molybdophosphoric acid

Journal Article · Wed Mar 01 04:00:00 EST 1989 · Journal of Catalysis; (USA)

DOI:https://doi.org/10.1016/0021-9517(89)90077-8· OSTI ID:6217670

Kasztelan, S; Moffat, J B ^[1]

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1. Univ. of Waterloo, Ontario (Canada)

Salts of 12-molybdophosphoric acid supported on silica were prepared by exchange of the supported parent acid with cesium, lithium, barium, magnesium, bismuth, aluminum, iron, silver, cobalt, chromium, copper, cadmium, mercury, nickel, and lead, or vanadyl cations. Each of the supported salts was compared with supported free 12-molybdophosphoric acid and with the silica-supported cation as catalysts in the oxidation of methane by N{sub 2}O. Three effects on the properties of the supported 12-molybdophosphoric acid catalyst due to the addition of cations have been discerned. One is attributable to the removal of protons by substitution, leading to the blocking of the oxygen extraction step which generates vacancies in the Keggin structure. This blocking effect does not depend on the nature or charge of the cation. The second effect appears to have an electronic basis and is strongly dependent on the nature of the cation. The relationship of this electronic effect to the electronegativity is discussed. A third effect of the added cation is the generation of new sites related to the intrinsic activity of the cations themselves.

• OSTI ID: 6217670
• Journal Information: Journal of Catalysis; (USA), Journal Name: Journal of Catalysis; (USA) Vol. 116:1; ISSN 0021-9517; ISSN JCTLA
• Country of Publication: United States
• Language: English

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