title: Magnetic resonance imaging studies on catalyst impregnation processes: discriminating metal ion complexes within millimeter-sized gamma-Al2O3 catalyst bodies.
abstract: Magnetic resonance imaging (MRI) was used to study the impregnation step during the preparation of Ni/gamma-Al(2)O(3) hydrogenation catalysts with Ni(2+) metal ion present in different coordinations. The precursor complexes were [Ni(H(2)O)(6)](2+) and [Ni(edtaH(x))]((2-x)-) (where x = 0, 1, 2 and edta = ethylenediaminetetraacetic acid), representing a nonshielded and a shielded paramagnetic complex, respectively. Due to this shielding effect of the ligands, the dynamics of [Ni(H(2)O)(6)](2+) or [Ni(edtaH(x))]((2-x)-) were visualized applying T(2) or T(1) image contrast, respectively. MRI was applied in a quantitative manner to calculate the [Ni(H(2)O)(6)](2+) concentration distribution after impregnation when it was present alone in the impregnation solution, or together with the [Ni(edtaH(x))]((2-x)-) species. Moreover, the combination of MRI with UV-vis microspectroscopy allowed the visualization of both species with complementary information on the dynamics and adsorption/desorption phenomena within gamma-Al(2)O(3) catalyst bodies. These phenomena yielded nonuniform Ni distributions after impregnation, which are interesting for certain industrial applications.
authors.affiliation: Inorganic Chemistry and Catalysis group, Department of Chemistry, Faculty of Science, Utrecht University, Sorbonnelaan 16, 3508 TB Utrecht, The Netherlands.
authors.forename: Leticia
authors.initials: L
authors.lastname: Espinosa-Alonso
authors.forename: Anna A
authors.initials: AA
authors.lastname: Lysova
authors.forename: Peter
authors.initials: P
authors.lastname: de Peinder
authors.forename: Krijn P
authors.initials: KP
authors.lastname: de Jong
authors.forename: Igor V
authors.initials: IV
authors.lastname: Koptyug
authors.forename: Bert M
authors.initials: BM
authors.lastname: Weckhuysen