3359.     TEICHNER, S.  [Evolution of Surface Area of Fischer Catalysts During Reduction.]  Compt. rend., vol. 227, No. 8, 1948, pp. 478-480; Chem. Abs., vol. 43, 1949, p. 27.

        It has been shown by other workers that interaction between Ni and Co oxides and kieselguhr used as catalyst support occurs to some extent.  Visser and de Lange found evidence for the formation of Ni hydrosilicate bonds by X-ray diffraction studies.  Data are presented in this paper for surface area changes of a Ni-kieselguhr catalyst on heating in vacuum and reduction:

Treatment

Weight

loss,

percent

Surface Area

 

 

M.2 per gm.

of catalyst

after pre-

treatment

M.2 per

gm. original

catalyst

Evacuated 26 hr. at 20° C.

4.3

28

27

Evacuated 16 hr. at 180° C.

11.0

39

35

Reduced in H2 at 450° C. for 18 hr. followed by evacuation at 180° C. for 48 hr.

 

 

22.8

 

 

87

 

 

67

The authors postulate a laminar or montmorillonite structure for the metal oxide-kieselguhr complex of the unreduced catalyst.  The increase is area on heating or reduction is not a direct consequence of this structure but is due to holes formed by removal of O2, H2O, and CO2 during the heating or reduction.  However, the laminar structure does tend to prevent the collapse of the pore system and sintering.  These catalysts are prepared as basic carbonates of the active metals, and H2O and CO2 result from their decomposition.