PREPARATION, CHARACTERIZATION AND CATALYTIC BEHAVIOR OF COBALT-NIOBIACATALYSTS

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.