1058.    FORESTIER, H., AND LILLE, R.  [Variation in Catalytic Power of Ferromagnetic Substances at the Curie Point.]  Compt. Rend., vol. 23, 1937, pp. 204, 265-267; Brennstoff-Chem., vol. 18, 1937, p. 286; Chem. Abs., vol. 31, 1937, p. 2077.

        It has been shown that the speed of inauguration of the equilibrium reaction, 2CO=CO₂+C, in the presence of ferromagnetic metals changes whenever the catalyst Fe or Ni loses its ferromagnetism.  A series of ferromagnetic oxides of the type of the ferrites, Fe₃O₄, Fe₂O₃·SrO and Fe₂O₃·NiO, was investigated for the catalytic power on the inauguration of the water-gas equilibrium CO₂+H₂ = CO+H₂O in the temperature range of their Curie points of 350°-700°.  A CO₂:H₂ (55:45) mixture was used at a velocity of 1 l./hr.  The amount of H₂O formed in the reaction plotted against the temperature was used as the criterion for the catalytic efficiency.  IN the temperature range of the magnetic transition point, for Fe₂O₃·SrO 480°, for Fe₃O₄ 570°, decided maxima occurred in the curves.  Three curves for Fe₂O₃·NiO, giving results of 3 successive tests, reveal the progressive reduction of the catalyst.  In the first test a maximum in the Curie point of the Ni ferrite occurs at 595°, but in the following tests the Fe₂O₃·NiO obviously decomposes with formation of Fe₃O₄ as a second maximum point is observed at about 570°.  A thermomagnetic analysis confirms this.  It is suggested that 3 temporary increases in catalytic power are connected with the changes at the Curie point and are due to a special mobility of some of the superficial electrons at that point.