Studies on the reduction of an iron catalyst for ammonia synthesis: II. Mo¨ssbauer studies on the reduction of an iron ammonia synthesis catalyst at different temperatures

Abstract

Mo¨ssbauer studies of the kinetics of reduction of an iron catalyst for ammonia synthesis are reported. The reduction was performed in the range of temperatures between 350 and 400°C by a H 2-N 2 mixture using a Mo¨ssbauer in situ cell. Two parallel reactions took place during the catalyst reduction, namely reduction of magnetite and reduction of wustite. On the kinetic curves of iron formation, a deflection point was observed when the wustite reduction was over. The apparent activation energies for wustite and magnetite reductions were estimated and they are higher than the literature activation energies for phase boundary reactions of iron oxides.