Giuseppe Trunfio - Iron ions supported on oxides: Fe/Al2O3 vs. Fe/SiO2

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      Publication Details (including relevant citation   information):

      M. T.   Nechita, G.   Berlier, G.   Martra, S.   Coluccia,  F. Arena, G.   Italiano, G.   Trunfio, A. Parmaliana. Il   nuovo Cimento, 123 (2008)   10-11.

      Abstract:

      The effect of   the surface structure of the support on the nature and dispersion   of iron ions was studied by comparing low-loaded   Fe/SiO2  and   Fe/Al2O3 catalysts, prepared by the   “adsorption-precipitation” method. This method, based on the   electrostatic interaction between iron ions and the negatively   charged support surface, is effective in the preparation of   highly dispersed iron-supported catalysts, active in alkanes   selective oxidation reactions. The samples were haracterized by   DR UV-Vis and IR spectroscopies, coupled with NO adsorption and   to temperature programmed reduction (TPR) measurements. DR UV-Vis   and TPR show that after calcination in both catalysts mainly   isolated Fe3+  ions, a minor fraction of   2-d FeO

        x dimers/oligomers and a very   small fraction of 3-d oxidic particles are present. The results   indicate a higher ability of alumina in dispersing iron-supported   species. Despite the multiple sites possibly available for   hosting iron cations offered by the silica support, only two   types of iron species were identified by IR of adsorbed NO,   differing for the ability to form mono or trinitrosyl complexes   (that evolve into dinitrosyl ones, by decreasing NO pressure).   The same technique shows that at least five different types of   iron species are formed on the alumina surface, four of them able   to form only mononitrosyl complexes and one giving di-or   trinotrisylic adducts.

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