V. Parvulescu et al., PREPARATION, CHARACTERIZATION AND CATALYTIC BEHAVIOR OF COBALT-NIOBIACATALYSTS, Journal of molecular catalysis. A, Chemical, 135(1), 1998, pp. 75-88
Cobalt-niobia catalysts were prepared using the colloidal sol-gel tech
nique. Niobium chloride or niobia oxide were used as precursor. The di
fferences between the procedures used are due to the methods of prepar
ation of the colloidal suspensions and gelification. The catalysts wer
e characterised using adsorption and desorption curves of Kr and N-2 a
t 77 K, H-2-Chemisorption, XRD, FT-IR, XPS and electron microscopy inv
estigations. Preparation of these catalysts without experimental preca
utions led to a very inhomogeneous structural and textural material. I
n contrast, the colloidal sol-gel technique controls both the structur
e of the niobia oxide and the tailoring of cobalt. A strong metal supp
ort interaction effect (SMSI) was present irrespective of the sample p
reparation variant. Although the rate of butane hydrogenolysis was low
for all catalysts, a correlation between TOF and the catalyst crystal
lite size was found. Selectivity to methane, ethane, propane or to iso
merization also depends on the catalyst crystallite size. (C) 1998 Els
evier Science B.V. All rights reserved.