Synergistic effect of Zr and K promoters on iron-based catalysts in CO hydrogenation reaction

Abstract

There is a growing demand for decreasing fossil fuel usage. That being said, we should move toward renewable and sustainable energy sources. Iron-based catalysts are usually employed in this route. In this work, an incipient impregnation process was used for preparing four γ-Al₂O₃ supported iron-based catalysts with different weight percents including 20Fe/5Cu/γ-Al₂O₃, 20Fe/5Cu/2K/γ-Al₂O₃, 20Fe/5Cu/3Zr/γ-Al₂O₃ and 20Fe/5Cu/1.5Zr/1K/γ-Al₂O₃ under the pressure of 20 atm, the temperature of 285 °C, H₂ to CO ratio of one, and a gas hourly space velocity of 2 NL/ (h. gCat). BET, FE-SEM, XRD, H₂-TPR, ICP, and TEM techniques were used to determine the characteristics of the catalysts, while gas chromatography results were used to determine CO conversion and product selectivity. Due to the synergistic effect of the two promoters, the doubly-promoted catalyst exhibited a C₅⁺ selectivity of 64.2 %, surpassing both the Fe/Cu/γ-Al₂O₃ catalyst and the singly-promoted catalysts. This result highlights the enhanced performance of the doubly-promoted catalyst. Compared to the other catalysts prepared, the doubly-promoted catalyst demonstrated a higher carbon monoxide (CO) conversion rate of 67.7 % and yield of 43.5 %. Moreover, The results demonstrate the significant impact of Zr and K promoters of the synthesized Fe-based catalysts on hydrocarbon product distribution.