53c.   HALL, W. K., TARN, W. H., AND ANDERSON, R. B.  Studies of the Fischer-Tropsch Synthesis.  XIII.  Structural Changes of a Reduced Iron Catalyst on Reoxidation and on Formation of Interstitial Phases.  Jour. Phys. Chem., vol. 56, 1952, pp. 688-691; Chem. Abs., vol. 46, 1952, p. 10,582.

               Upon complete reduction at 450° or 550°, a fused Fe synthetic NH₃ catalyst develops an extensive pore structure corresponding to about 45% porosity.  On reoxidation, the volumes of the individual particles remain constant, while the surface areas and pore volumes decrease.  Reoxidation proceeds at an initially rapid rate, which becomes very slow after a few hours.  The reoxidized catalyst is reduced much more easily than the raw catalyst.  Formation of the interstitial nitrides and carbides causes the catalyst particles to expand and the pore volume and average pore diameters to increase.  The % porosity, however, remains about constant.

               ANDERSON, R. B., KRIEG, A., SELIGMAN, B., AND TARN, W. H.  Studies of the Fischer-Tropsch Synthesis.  III.  Influence of Type of Kieselguhrs.  See abs. 46.