Effect of La2O3 doping on syntheses of C1-C18 mixed linear α-alcohols from syngas over the Co/AC catalysts

Activated carbon-supported La-promoted Co catalysts with different La dopings (15Co-xLa/AC) were prepared by the co-impregnation method and investigated by means of CO hydrogenation, XRD, TPR-MS, CO adsorption and TPSR-MS techniques. The results showed that mixed linear alpha-alcohols (C-1-C-18) can be directly synthesized from syngas over the La-doped 15Co/AC catalysts under mild conditions and that the selectivity towards alcohols was improved by doping La into the 15Co/AC catalysts. It was found that the reducibility of the 15Co-xLa/AC catalyst decreased and the Co dispersion improved due to the strong interaction between Co and La2O3 species. La2O3 can promote the formation of cobalt carbides (Co2C) which are postulated to play an important role in the syntheses of the mixed linear alpha-alcohols. On the other hand, high Co dispersion and an appropriate ratio of Co2+/Co-0 can enhance the activity of CO hydrogenation. (C) 2009 Elsevier B.V. All rights reserved.