NO adsorption study on the distribution of nickel ions on the mixed carriers of USY zeolite and g-Al O 2 3

In this paper, the distribution of Ni2q ions on various carriers, such as USY zeolite, g-alumina and their mixed carriers, is studied according to their NO adsorption. When Ni2q ions locate on SII , SIIX SIX.sites of USY zeolite or on the surface of alumina, the IR spectra of their NO adsorption show bands at 1905, 1900 or 1855–1875 cmy1, respectively. The later band shifts to higher wavenumber with the increase of alumina content in mixed carriers. When NiO loading on NiOrAl2O3 samples is less than 8 wt.%, the Ni2q ion distribution has an equilibrium between the surface and the bulk of g-alumina. The proportion is about one-third. On mixed carriers, this equilibrium is broken up. Ni2q ions are more easily enriched on the surface of g-alumina. Ni2q ions slightly prefer to occupy SIIX , SIX sites rather than SII sites of USY zeolite when mixed carrier contains less than 40 wt.% alumina. On USY zeolite, Ni2q ions prefer to occupy its SIsites rather than its SII , SIIX and SIX sites. The tendency strengthens obviously with the increase of NiO loading. q1999 Elsevier Science B.V. All rights reserved.