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

The effects of manganese and potassium on the structural and morphological properties, phase compositions and CO adsorption behavior of the CNT-confined FeN catalyst were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), 57Fe Mössbauer effect spectroscopy (MES) and CO temperature-programmed desorption (TPD). The results suggested that the presence of manganese helps retain nitrogen in cubic FeCxN1−x and facilitates CO adsorption. The selectivity to C2double bond; length as m-dashsingle bondC4double bond; length as m-dash 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 (C5+), similar to the conventional reduced iron catalysts.