Study of reaction conditions in the hydrogenation of CO2 to hydrocarbons using an FeCu_CNT catalyst

Abstract

This study optimized the catalytic performance of an FeCu_CNT catalyst in CO₂ hydrogenation to hydrocarbons by evaluating the influence of temperature (between 250 and 450 °C), pressure (between 10 and 30 bar), reactants flow ratio (H₂ : CO₂ ratio of 5 : 1, 3 : 1, 2 : 2, 1 : 3), catalyst mass (200, 500 and 1000 mg) and reaction time (100 h). Catalytic tests revealed that reaction conditions significantly influenced CO₂ conversion and product selectivity. The optimal temperature for C₂–C₄ hydrocarbon synthesis was 350 °C, while a pressure of 15 bar enhanced selectivity without compromising CO₂ conversion. Under these conditions, the catalyst achieved a CO₂ conversion of 34.2% and a C₂–C₄ selectivity of 24.5%. A H₂ : CO₂ molar ratio of 3 : 1 favored the formation of light hydrocarbons, and the catalyst mass had a minimal impact on conversion, with selectivity remaining unaffected. Despite an initial activity drop within the first 20 h (where conversion decreased by ∼7% and C₂–C₄ selectivity by ∼15%), the catalyst demonstrated stability over 100 h, maintaining efficiency. Characterization using H₂-TPR, N₂ adsorption–desorption, TGA, ICP-OES, XPS and XRD analysis confirmed that after the stability test, the catalyst did not undergo significant structural changes and maintained its physical integrity and the changes observed were primarily chemical.