Study on the preparation of [formula omitted] catalysts for ammonia synthesis at mild conditions followed by Mössbauer spectroscopy

Abstract

The state of iron in novel KCFe Al 2O 3 catalysts for ammonia synthesis at mild conditions was studied by Mössbauer spectroscopy and X-ray diffraction. The activities of the catalysts were found to be comparable or even higher than the activity of the commercial contact. Two catalysts differing in iron loading were examined after every stage of preparation. The high (ca. 33 wt.%) and low (ca. 11 wt.%) Fe content resulted in a different behavior of iron during the catalyst preparation and different iron forms were found in the active contacts. In the catalyst with high iron loading the difference in Fe dispersion was observed while the low loading contact contained mainly Fe(III) species. Both highly dispersed iron and Fe(III) species were influenced by potassium, this being concluded from the Mössbauer parameters calculated for these forms.