Abstract: | Studies on the structural changes and catalytic behavior of iron-manganese catalysts for CO hydrogenation were conducted using Mossbauer spectroscopy, X-ray diffraction, temperature programmed reduction and kinetic measurements. It was observed that the reduction of the mixed oxide catalyst precursors proceeds via the formation of Fe3-xMnxO4,Mn3-xFexO4 mixed spinel and Fe1-zMn2O mixed oxide to α-iron and MnO. After use for CO hydrogenation, catalysts are oxidized as well as carburized. The Mn3-yFeyO4 mixed spinel and Fe1-2MnzO mixed oxide are the most powerful phases for olefin production. The highest attainable 2–4 low carbon olefin selectivity is 41% with an 86% conversion level. Higher manganese content or lower reduction temperatures may change the carbide formed from χ-Fe5C2 to the more unstable ?′-Fe22C. Carbide formation is greatly dependent on manganese content and activation procedure used. |