title: Tomographic energy dispersive diffraction imaging to study the genesis of Ni nanoparticles in 3D within gamma-Al2O3 catalyst bodies.
abstract: Tomographic energy dispersive diffraction imaging (TEDDI) is a recently developed synchrotron-based characterization technique used to obtain spatially resolved X-ray diffraction and fluorescence information in a noninvasive manner. With the use of a synchrotron beam, three-dimensional (3D) information can be conveniently obtained on the elemental composition and related crystalline phases of the interior of a material. In this work, we show for the first time its application to characterize the structure of a heterogeneous catalyst body in situ during thermal treatment. Ni/gamma-Al(2)O(3) hydrogenation catalyst bodies have been chosen as the system of study. As a first example, the heat treatment in N(2) of a [Ni(en)(3)](NO(3))(2)/gamma-Al(2)O(3) catalyst body has been studied. In this case, the crystalline [Ni(en)(3)](NO(3))(2) precursor was detected in an egg-shell distribution, and its decomposition to form metallic Ni crystallites of around 5 nm was imaged. In the second example, the heat treatment in N(2) of a [Ni(en)(H(2)O)(4)]Cl(2)/gamma-Al(2)O(3) catalyst body was followed. The initial [Ni(en)(H(2)O)(4)]Cl(2) precursor was uniformly distributed within the catalyst body as an amorphous material and was decomposed to form metallic Ni crystallites of around 30 nm with a uniform distribution. TEDDI also revealed that the decomposition of [Ni(en)(H(2)O)(4)]Cl(2) takes place via two intermediate crystalline structures. The first one, which appears at around 180 degrees C, is related to the restructuring of the Ni precursor on the alumina surface; the second one, assigned to the formation of a limited amount of Ni(3)C, is observed at 290 degrees C.
authors.affiliation: Inorganic Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Sorbonnelaan 16, 3584 CA Utrecht, The Netherlands.
authors.forename: Leticia
authors.initials: L
authors.lastname: Espinosa-Alonso
authors.forename: Matthew G
authors.initials: MG
authors.lastname: O'Brien
authors.forename: Simon D M
authors.initials: SD
authors.lastname: Jacques
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Beale
authors.forename: Krijn P
authors.initials: KP
authors.lastname: de Jong
authors.forename: Paul
authors.initials: P
authors.lastname: Barnes
authors.forename: Bert M
authors.initials: BM
authors.lastname: Weckhuysen