IR AND ESR STUDY OF THE REACTIVITY OF ISO BUTYRIC ACID ON 1-VANADO-11-MOLYBDOPHOSPHORIC ACID AND ITS SODIUM-SALT

The alkaline salt of 1-vanado-11-molybdophosphoric acid has been inves tigated in isobutyric acid absorption-desorption-reoxidation cycles by IR and ESR spectroscopies in comparison to the bulk acid compound. Th e stability of the active phase in catalysis seems to be related to th e formation of a cubic phase depending strongly on tile presence of wa ter vapor in the gas stream. This phase can be generated from an alkal i precursor subject to a moderate thermal treatment leading to a dispe rsion of dioxovanadium cation into the alkali-12-molybdophosphate latt ice.