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 from 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 maintained almost unchanged over periods up to 100 h, operating at carbon monoxide conversions of over 40%. Both X-ray photoelectron spectroscopy and temperature-programmed reduction profiles show that for the unpromoted catalyst, the presence of Co3O4 lowers the reduction temperature of CeO2, while for the promoted catalyst, the addition of ruthenium lowers the reduction temperatures of both Co3O4 and CeO2 further, presumably via hydrogen spillover reduction. Consequently there is more Co0 on the ruthenium-promoted catalyst than the unpromoted catalyst leading to higher activity. Fuel parameters of the n-alkane condensate include high cetane index (80-100) and intermediate pour point (- 4-degrees-C), showing suitability for fuel oils or blends.