RUTHENIUM PROMOTION OF FISCHER-TROPSCH SYNTHESIS OVER COPRECIPITATED COBALT CERIA CATALYSTS

A reduced co-precipitate of cobalt and cerium oxides has been found to be selective for production of lower alkenes and higher n-alkanes fro m syngas, with the advantage of low (ca. 1 wt.-%) carbon dioxide as a co-product. Activity is trebled by adsorption of as little as 0.3 wt.- % ruthenium, as Ru3(CO)12, without loss of selectivity. Activity is ma intained almost unchanged over periods up to 100 h, operating at carbo n monoxide conversions of over 40%. Both X-ray photoelectron spectrosc opy and temperature-programmed reduction profiles show that for the un promoted catalyst, the presence of Co3O4 lowers the reduction temperat ure of CeO2, while for the promoted catalyst, the addition of rutheniu m lowers the reduction temperatures of both Co3O4 and CeO2 further, pr esumably via hydrogen spillover reduction. Consequently there is more Co0 on the ruthenium-promoted catalyst than the unpromoted catalyst le ading to higher activity. Fuel parameters of the n-alkane condensate i nclude high cetane index (80-100) and intermediate pour point (- 4-deg rees-C), showing suitability for fuel oils or blends.