Effect of silica and alumina promoters on co-precipitated Fe–Cu–K based catalysts for the enhancement of CO2 utilization during Fischer–Tropsch synthesis

• CO2 in syngas over a given amount could be catalytically converted to FT products.
• 88.3% CO and 25.2% CO2 in 54% H2/10% CO/29% CO2/7% N2 syngas was converted over Fe–Cu–K–Si–Al.
• Only 81.8% CO and 18.8% CO2 in 54% H2/10% CO/29% CO2/7% N2 syngas was converted over Fe–Cu–K.
• Increasing CO2 in syngas increased C5+ selectivity but decreased CH4 selectivity.
• 50.1% CO2 at balanced H2/CO2 = 3 converted over Fe–Cu–K–Si–Al with 64.2% C5+ selectivity.

Silica and alumina were used as structural promoters to increase the catalytic activity of a co-precipitated Fe–Cu–K catalyst for the CO2 and CO hydrogenation during Fischer–Tropsch (FT) synthesis. The doubly-promoted Fe–Cu–K–Si–Al catalyst achieved higher CO and CO2 conversions than the Fe–Cu–K catalyst and singly-promoted Fe–Cu–K–Al and Fe–Cu–K–Si catalysts. The CO and CO2 conversions of the syngas with 54% H2/10% CO/29% CO2/7% N2 over the doubly-promoted catalyst were 88.3% and 25.2%, respectively, compared to 81.8% and 18.5% for the Fe–Cu–K catalyst. In this case, the C5+ selectivity of the doubly-promoted catalyst was 71.9%, which was slightly lower than 75.5% for the Fe–Cu–K catalyst. The CO2 was converted to hydrocarbons using the doubly-promoted catalyst when the CO2/(CO + CO2) ratio was higher than 0.35 for H2-balanced syngas at H2/(2CO + 3CO2) = 1.0, and 0.5 for H2-deficient syngas at H2/(2CO + 3CO2) = 0.5. The increase of hydrogen content in the syngas increased the methane selectivity at the expense of decrease in the liquid hydrocarbon selectivity.

Figure optionsDownload as PowerPoint slide