48.    ANDERSON, R. B., HALL, W. K., KRIEG, A., AND SELIGMAN, B.  Studies of the Fischer-Tropsch Synthesis.  V.  Activities and Surface Areas of Reduced and Carburized Cobalt Catalysts.  Jour. Am. Chem. Soc., vol. 71, 1949, pp. 183-188; Chem. Abs., vol. 43, 1949, p. 3273.

               This paper relates surface area and surface accessibility of the catalyst to activity and product distribution.  Data reported previously on the effect of bulk carbide on the activity of Co catalysts have been extended to include surface areas and activities and distribution of products in the synthesis with catalysts carburized with CO under conditions that form carbide (CO₂C), free C, or both.  The catalysts studied were CO : ThO₂ : MgO : kieselguhr (100 : 6 : 12 : 200) and Co : ThO₂ : kieselguhr (100 : 18 : 100)l.  The surface of the catalyst was found to be heavily covered with hydrocarbon.  Hydrogenation at 200° removed 90% of these adsorbed hydrocarbons, and reduction with H₂ at 400° restored the catalyst to the same condition as after the initial reduction.  There was no evidence of sintering or of C deposition.  Activity data for operation at 1 and 7.8 atm. are related to the adsorbed hydrocarbon film.  Decrease in the accessibility of the surface of these catalysts either by deposition or excessive quantities of wax or by reduction of average pore diameter by pelleting caused an increase in the fraction of CH₄ and other light hydrocarbons and in some cases a decrease in activity.  The presence of bulk-phase carbide in these catalysts caused a marked decrease in activity, but free C did not affect the activity very much.  The presence of C in both forms shifted the product distribution toward light hydrocarbons.  The surface area did not change appreciably when the Co was converted to carbide.  Carburization at 275°, under conditions that form predominantly free C, increased the area considerably.