CO₂ Hydrogenation to Hydrocarbons over Fe/BZY Catalysts

This manuscript reports a CO₂ hydrogenation process in a catalytic laboratory-scale packed-bed reactor using an Fe/BZY15 (BaZr_0.85Y_0.15O_3-δ) catalyst to form hydrocarbons (e. g., CH₄, C₂₊) at elevated pressure of 30 bar and temperatures in the range (Formula presented.) °C. The effects of temperature, feed composition (i. e., CO₂/H₂ ratio, and residence time (i. e., Weight Hourly Space Velocity (WHSV) are studied to understand the relationship between CO₂ conversion and carbon selectivity. Catalyst characterization elucidates the relationships between the catalyst structure, surface adsorbates, and reaction pathways. Thermodynamic analyses guide the experimental conditions and assist in interpreting results. While the feed composition and temperature influence the product distribution, the results suggest that the higher-carbon (C₂₊) selectivity and yield depend strongly on residence time. The results suggest that the CO₂ hydrogenation reaction pathway is similar to Fischer–Tropsch (FT) synthesis. The reaction begins with CO₂ activation to form CO, followed by chain-growth reactions similar to the FT process. The CO₂ activation depends on the redox activity of the catalyst. However, the carbon chain growth depends primarily on the residence time. as is the case for the FT synthesis, high residence time (on the orders of hours) is required to achieve high C₂₊ yield.