Incorporation of promoter elements into the crystal lattice of (VO) 2P 2O 7 and its promotion effects on the oxidation of n-butane to maleic anhydride

Abstract

A new preparation method to introduce promoter ions into the (VO 2)P 2O 7crystal lattice was developed. A precipitate was obtained by the addition of a small amount of water to a blue isobutanol refluxing solution which contained reduced and dissolved V 2O 5 and the acetylacetonate of a promoter element. The catalyst which was prepared by the calcination of this precipitate had the same composition as that of the starting solution. Observation of the catalyst using energy-dispersive X-ray and wavelength-dispersive X-ray showed no evidence of localization of the added promoter element. The ESCA (electron spectroscopy for chemical analysis) depth profile of the component elements suggested a homogeneity between the surface and the bulk of the catalyst. There is a linear relationship between the activity of the catalysts for MA formation and the position of the V-O IR absorption bands of the catalysts containing promoter elements. The active sites of the catalysts and the activity of the surface V-O are discussed.