FeN particles confined inside CNT for light olefin synthesis from syngas: Effects of Mn and K additives

摘要

The effects of manganese and potassium on the structural and morphological properties, phase compositions and CO adsorption behavior of the CNT-conflned FeN catalyst were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), ~(57)Fe Mossbauer effect spectroscopy (MES) and CO temperature-programmed desorption (TPD). The results suggested that the presence of manganese helps retain nitrogen in cubic FeC_xN_(1-x) and facilitates CO adsorption. The selectivity to C2~=-C4~= light olefins is enhanced over Mn(1.0 wt%)/FeN/CNT although the activity decreases within the loading range of 0.5-2.0 wt% for Mn. Although further promotion with K could improve the activity slightly, the selectivity to light olefins decreases. At the same time, the addition of potassium enhanced the water gas shift activity and shifted the selectivity to heavy hydrocarbons (C_(5+)), similar to the conventional reduced iron catalysts.