Improvement of Liquid Hydrocarbon Yield in CO2 Fischer–Tropsch Synthesis over Potassium-added Iron Carbide Catalyst

Abstract

Potassium addition to iron carbide catalysts (FeCx) was investigated for the promotion of synthesis of liquid hydrocarbons (C5＋) through CO2 hydrogenation via Fischer_Tropsch synthesis (CO2-FTS). Potassium added iron carbide catalysts (K_FeCx) with various potassium contents were prepared by the thermal decomposition of iron oxalate dihydrate and potassium nitrate under CO gas flow. The C5＋,others yields and the CH4 yields obtained by the CO2-FTS over K(z)_FeCx catalysts (K/Fe＝z/100, z＝0, 1, 5, and 10 in molar ratio) were compared. The highest C5＋,others yield and lower CH4 yield were achieved by the CO2-FTS over the K(1)_FeCx catalyst among the prepared catalysts. The K(1)_FeCx catalyst contained the highest amount of χ-Fe5C2 phase which is the active site of FTS. The yield of liquid hydrocarbon was improved using the K(1)_FeCx catalyst due to the lesser coverage of FTS active sites by potassium compared to the catalysts with excess potassium added.