Determination of Fe2+/Fe3+ mole ratio based on the change of precursor lattice parameters of wustite based iron catalysts for the ammonia synthesis

• Main Authors: Jurkowski Artur, Lendzion-Bieluń Zofia
• Format: Article
• Language: English
• Published: Sciendo 2019-09-01
• Series: Polish Journal of Chemical Technology
• Subjects: wustite ammonia catalyst; xrd technique; manganometry; wustite lattice parameter
• Online Access: https://doi.org/10.2478/pjct-2019-0029

In the presented article, oxide forms of iron catalysts with the wustite structure and with a R = Fe2+/Fe3+ molar ratio in the range from 3.78 to 8.16 were investigated. The chemical composition of the tested catalyst precursors was determined by inductively coupled plasma optical emission spectrometry (ICP-OES). The X-ray diffraction (XRD) technique was used to determine the phase composition and location of reflections characteristic of the Fe1−xO phase. The molar ratio of iron ions R = Fe2+/Fe3+ was determined by manganometric titration. The distribution of promoters in the structure of iron catalyst precursors with different R = Fe2+/Fe3+ ratio was determined by a selective etching method. The dependence of the lattice parameter ao value in the crystal structure Fe1−xO on the molar ratio R = Fe2+/Fe3+ was determined. On the basis of the determined dependence, R can easily be calculated in catalyst precursors of the wustite structure.