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 C2C4 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.

The presence of Mn additive in FeN/CNT enhances the selectivity to C2C4 light olefins although the activity decreases in syngas conversion. However, the addition of K to Mn(1.0 wt%)/FeN/CNT could not further improve the selectivity to light olefins.Figure optionsDownload high-quality image (361 K)Download as PowerPoint slideHighlights
► The effects of Mn and K as additives on CNT-confined FeN catalysts have been studied in light olefin synthesis from syngas.
► The presence of Mn helps retain nitrogen in cubic FeCxN1−x during reaction and facilitates CO adsorption.
► The selectivity to C2C4 light olefins increases although the activity decreases within the loading range of 0.5–2.0 wt% for Mn.
► Further promotion with K could improve the activity slightly, the selectivity to light olefins decreases.