ИСТИНА

Magnetic materials have attracted the attention of many researchers because of their excellent physical and chemical properties, such as superparamagnetism, high surface area, easy separation under external magnetic fields, etc. There are interesting, that the combination of Fe–Co catalyst with or without promoters favors the formation of C2–C4 alkenes in Fischer–Tropsch Synthesis (FTS) and it favors Fe–Co alloy formation. Reports in the patent literature on the synthesis and study of a series Fe/Co Fischer–Tropsch catalysts have indicated that the addition of small amounts of Co to Fe could influence the Fe catalyst and could have an enhanced activity comparison to the individual metal oxides [1]. The present work describes physical and chemical properties of the bimetallic systems FeCo/MgO•Al2O3, prepared by different methods and the behavior of this system in CO hydrogenation process. The Co/Fe/support catalysts were prepared by means of sequential and joint impregnation of MgO•A2lO3 support by Co and Fe nitratе salts. We showed by means of magnetic method in situ [2] that the CoFe/support catalyst had the highest reduction degree, if Fe was applied on the support at first and then Co. The activation energy of the reduction process is 18.7 kkal/mol. The results of Messbauer spectroscopy showed that the size of oxide particles for this catalyst was much larger than for the catalyst prepared by joint impregnation by nitrate salts. In the former case the size of catalyst particles is close to one of superparamagnetic particles (<7 nm). The magnetization of the catalyst decreased due to formation of Fe carbide during CO hydrogenation process. The results of XPS showed that cobalt particles place on the supports surface and play the role of promoter in the CO hydrogenation process. Consequently, the CoFe/MgO*Al2O3 catalyst has the highest catalytic activity of other catalysts.