Influence of Ammonia and Different Promoters on the Iron-Based Fischer-Tropsch Synthesis

The material properties of precipitated iron promoted with either K, Mn, Pt, Ru, Zn, respectively, and their catalytic performance in the Fischer-Tropsch synthesis were evaluated. A special attention was paid to the influence of ammonia on the reaction. Different spectroscopic methods e. g. XPS and XANES revealed the structure of both iron and the corresponding promoter. Conclusions were also drawn for the activated (reduced) catalysts. Applying temperature programmed reduction and XRD, the presence of iron nitrides through ammonia treatment was discovered. In the presence of ammonia under the Fischer-Tropsch reaction conditions the formation of amines was detected. The highest yield of amines was observed for the manganese promoted catalyst. The investigation of hydrogen activating and not activating promoters in combination with iron, made it possible to hypothesise about the mechanism of the incorporation of ammonia into hydrocarbons under Fischer-Tropsch reaction conditions. The influence of ammonia on the Fischer-Tropsch synthesis is investigated. Conclusions about the mechanism of formation of hydrocarbons and amines are drawn from the performance data. Iron-based catalysts with different promoting elements (K, Mn, Pt, Ru, Zn) are evaluated. The catalysts are characterized by XRD, XPS, XANES and iTPR. image