CO-hydrogenation over silica supported iron based catalysts: Influence of potassium loading

Graphical abstract: Five different Fe–Cu/SiO2 catalysts were prepared by a combination of co-precipitation and wet impregnation technique at different K-loading ranging from 0 to 5 wt.% for the conversion of syngas to liquid fuel. Detailed Catalyst characterization was done by BET, TPR, TGA, XRD and TEM techniques. Maximum CO-hydrogenation obtained near to 1% K-loading and catalytic activity decreased at 3% and 5% K loading. Display Omitted - Highlights: • CO-hydrogenation was performed with K promoted Fe–Cu/SiO2 catalysts at different K-loading from 0.0 to 5.0 wt%. • Catalyst characterization was done by BET, TPR, TPD, TG-DTA, XRD, SEM–EDX and TEM techniques. • Maximum CO-hydrogenation obtained with 1% K-loading, further activity decreased with 3% and 5% K-loading. • Effect of K-promoter towards conversion, selectivity and deactivation of catalysts was studied for FT-process. - Abstract: Five different Fe–Cu/SiO2 catalysts were prepared by a combination of co-precipitation and wet impregnation technique at different K-loading ranging from 0 to 5 wt.% for the conversion of syngas to liquid fuel. The physiochemical characterization of these catalysts was performed by using N2 adsorption, X-ray diffraction (XRD), H2-TPR, NH3-TPD, TEM, Inductive Couple Plasma Mass Spectroscopy (ICP-MS), and SEM–EDX to study the effect of potassium on the textural properties, structural change, reduction behavior, acidity and morphological change to the above K-loading catalysts. The effect of addition of potassium promoter was studied for CO-Hydrogenation in a fixed bed reactor simultaneously with the effect of promoter on the CO-conversion, selectivity and deactivation. The maximum catalytic activity was obtained from 1% K-loading and the catalytic activity decreased thereafter. The activity for water–gas shift (WGS) also enhanced with increasing K loading. The results revealed that increasing K loading decreases gaseous hydrocarbon formation and shifts selectivity to higher molecular weight hydrocarbons. Incorporation of potassium suppresses the hydrogenation activity of the Fe–Cu/SiO2 catalyst, leading to higher olefin yield in the products