Preparation, characterization and NH3-SCR activity of FeVO sub(4) supported on TiO sub(2)-WO sub(3)-SiO sub(2)

A series of FeVO sub(4) catalysts supported on TiO sub(2)-WO sub(3)-SiO sub(2) based oxides were prepared and studied in the ammonia SCR reaction. Their characteristics have been studied by X-ray powder diffraction, X-ray fluorescence, surface area measurements, Mossbauer spectroscopy and temperature programmed methods. It is shown that homogeneity of starting FeVO sub(4) powder is one of the parameters that governs the activity of the final catalytic material. Stoichiometric or Fe/V rich compositions can be obtained by varying the pH of precipitation; this affects interaction with the support and thermal stability, which in turn modifies SCR activity. Homogeneous FeVO sub(4) shows the highest activity and thermal stability which might be correlated with the characteristics of Fe super(3+)-O-V super(5+) bond and the acidity of the V-O moiety. Both vanadium and iron excess promote phase evolution of the support with formation of rutile and consequent surface area loss at much lower temperature.