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.