EFFECTS OF DISPERSION AND METAL-METAL OXIDE INTERACTIONS ON FISCHER-TROPSCH SYNTHESIS OVER RU TIO2 AND TIO2-PROMOTED RU/SIO2/

The activity of Ru/TiO2 and TiO2-promoted Ru/SiO2 catalysts for Fische r-Tropsch synthesis has been investigated. The Ru dispersion of these catalysts was determined by TEM, and the fraction of the Ru surface av ailable for H-2 adsorption was determined by H-1 NMR. Even after low-t emperature reduction, the surface of titania-containing catalysts is c overed by titania to a substantial degree. The specific activity and s electivity of these catalysts are dominated by the interactions occurr ing between the Ru particles and the titania overlayer. As the fractio n of the Ru particle surface covered by titania increases, the turnove r frequency for CO consumption passes through a maximum, while that fo r methane formation decreases monotonically. The probability for chain growth and the olefin-to-paraffin ratio of the products increase with increasing titania coverage. These trends are attributed to the effec ts of the titania overlayer on the catalytic properties of Ru. (C) 199 4 Academic Press, Inc.