The role of vanadium on the properties of iron based catalysts for the water gas shift reaction

The substitution of chromium by vanadium as dopant in the iron oxide based water gas shift (WGS) catalyst has been investigated. Catalysts prepared as magnetite with different amount of vanadium have been prepared and tested with different amounts of water in the gas feed. The results obtained showed that vanadium was a promising dopant leading to very active and stable catalysts. The vanadium-doped catalysts have been characterized by means of chemical analysis, X-ray diffraction, Fourier transform infrared spectroscopy, specific surface area measurements. temperature-programmed reduction, Mossbauer spectroscopy, X-ray photoelectron spectroscopy and high resolution transmission electron microscopy with electron diffraction. Vanadium has been shown to be present both as V(III) and V(IV) species at the surface and in the bulk near the surface of the magnetite structure. It increased the specific surface area of the catalysts and kept the particles apart on the surface delaying sintering. The vanadium doping has been shown to have also an effect on the Fe(111) content of the magnetite which increased favoring the successive oxidation and reduction cycles, during the reaction. (c) 2005 Elsevier B.V. All rights reserved.