3425.     ---------------.  [TRAMBOUZE, Y.]  [Study of Fischer Nickel Catalysts by Differential Thermal Analysis.]  Compt. rend., vol. 230, 1950, p. 1169-1171; Chem. Abs., vol. 44, 1950, p. 7132.

        Ni hydroxide and the gel formed by precipitating Ni with K₂CO₃ are heated to 500° for 1.5 hr.  Both show the dehydration of the hydroxide at 360°-380° by a strong endothermic reaction; the second also shows the loss of adsorbed H₂O at 100° and the decomposition of the basic carbonates into CO₂, H₂O, and NiO at 220°-240°.  Four other studies, one with a 1:1 mixture of kieselguhr and Ni hydroxide heated slowly, the other with catalysts heated variously to produce a silicate content of 15%, 8% and 0%, do not show the dehydration curve but do show the carbonate decomposition and, in the pertinent cases, another reaction at 400°, presumably hydrosilicate formation.  When the contact mass is heated for a long time at 220°, the total decomposition of the basic carbonates and complete dehydration of the hydroxide make further combination impossible.  A close relation between the precipitation conditions and the activity of a Fischer catalyst can now be established.