Effect of lanthanum loading in Fe-K/La-Al2O3 catalysts for CO2 hydrogenation to hydrocarbons

Lanthanum-modified alumina supports prepared by the impregnation method hav e been used as supports for potassium-promoted iron catalysts in CO2 hydrog enation, The catalysts have been characterized by X-ray diffraction, CO2 ch emisorption, temperature-programmed reduction (TPR) and temperature-program med decarburization (TPDC) techniques. The selectivity towards total hydroc arbons and lower olefins (C-2-C-4) was found to increase with increase in l anthanum content up to 4 wt% in Fe-K/La-Al2O3 catalysts and to decrease abo ve this lanthanum content. The TPR profiles of the catalysts of lanthanum-m odified Al2O3 shows the reduction of Fe2O3 to iron(0) follows a three-stage reduction mechanism through formation of the FeO phase. The TPDC profiles show the formation of three types of carbide species on the catalysts durin g the reaction. The activities of the catalysts are correlated with physico -chemical characteristics of the catalysts. Copyright (C) 2000 John Wiley & Sons, Ltd.