Promotion effect of Fe-Cu catalyst for the hydrogenation of CO2 and application to slurry reactor

The hydrogenation of CO2 to hydrocarbons over precipitated iron catalysts w as carried out in a stirred tank slurry reactor. Effects of potassium promo tion and structural promotion using Al2O3 :or SiO2 on the activity and sele ctivity were investigated with the co-precipitated Fe-Cu-Al (or Si)-K catal ytic system. Also, tha-reaction performance in the slurry reactor was compa red: with that in a fixed-bed reactor. The addition of either Al2O3 or SiO2 by the mixing method gave hardly any improvement in the catalytic activity or selectivity in CO2 hydrogenation. Instead, the addition of SiO2 by the mixing method lowered the selectivities to long-chain hydrocarbons and olef ins, However, the addition of Al2O3 by co-precipitation increased CO2 conve rsion as well as the selectivity to C2+ hydrocarbons, but decreased the sel ectivity to CO. The addition of potassium promoted the CO2 hydrogenation ac tivity and the selectivity to hydrocarbons, shifted the product distributio n to the direction of olefins and long-chain hydrocarbons, In terms of CO2 conversion and hydrocarbon selectivity, K/Fe = 6/100 is the optimum K level at the-conditions employed in the present study. The comparison of slurry and fixed-bed reactors showed that the slurry reactor was not as favorable as the fixed-bed reactor for CO2 hydrogenation, (C) 2000 Elsevier Science B .V. All rights reserved.