CHARACTERIZATION OF ALKALI-DOPED NI SIO2 CATALYSTS/

The effects of the alkali doping on the reducibility and morphological properties together with distribution and crystallography of phases o f a Ni/SiO2 catalyst have been investigated by N-2 adsorption measurem ents, diffuse reflectance TR Fourier transform spectroscopy (DRIFTS), CO adsorption, DRIFTS determinations, temperature-programmed reduction (TPR), X-ray diffraction line broadening (XRDLB), H-2 chemisorption, and TEM observations. Alkaline dopants produce an increase in the weak ly adsorbed fraction of hydrogen and important changes in the adsorpti on modes of CO. Lithium and potassium modify the distribution of Ni ac ross the support, inducing sintering phenomena, while sodium keeps nic kel particle dispersion.