642.    CRAXFORD, S. R., AND POLL, A.  [Reduction of Catalysts With a Cobalt and Kieselguhr Base Utilized in the Fischer-Tropsch Synthesis.]  Jour. Chim. Phys., vol. 47, 1950, pp. 253-257; Chem. Abs., vol. 44, 1950, p. 8086.

     Catalysts having the composition Co:ThO₃:MgO:kieselguhr in the ratio 100:6:12:200 were used.  The most active catalyst was obtained by carrying out the reduction at 400° in pure dry H₂ at a flow rate of 6,000 vol./vol. of catalyst/hr.  When H₂ saturated with H₂O vapor at room temperature was used for reduction, the surface area of the reduced portion of the catalyst was slightly greater than that observed with dry H₂, but the amount of reduction was appreciably less.  The % reduction of Co oxide after treatment with dry H₂ under the above conditions was 29.8 at 30°, 53.2 at 350°, 71.2 at 400°, 81.3 at 450°, and 91.5 at 500°.  A reduction temperature of 400° caused the least diminution of the surface area after vacuum treatment at 450° for 4 hr.  A reduction in surface area from 229 m.²/gm. of Co to 180 m.²/gm. occurred when the catalyst was used in synthesis.  Along with x-ray data, the diminution in surface area suggested that appreciable agglomeration of Co occurred during use of the catalyst.  Catalyst were prepared in 5 different manners to investigate the role of the formation of a hydrosilicate on the reduction.  Conditions favoring the formation of a hydrosilicate appreciably decreased the ease of reduction.  A catalyst that was maintained at an elevated temperature under pressure in an autoclave during preparation could not be reduced with H₂ at 800°.  The minimum amount of reduction in surface area occurred under conditions of catalyst preparation that did not favor formation of a hydrosilicate.