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Structural Changes of a U 3 O 8 /ZrO 2 Catalyst During HCl Oxidation – a HAADF‐STEM Study
Author(s) -
Krumeich Frank,
Amrute Amol P.,
Mondelli Cecilia,
PérezRamírez Javier
Publication year - 2014
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.201300490
Subject(s) - catalysis , uranium , oxide , uranium oxide , materials science , cubic zirconia , heterogeneous catalysis , inorganic chemistry , chemical engineering , crystallography , chemistry , metallurgy , engineering , ceramic , biochemistry
Uranium oxide finely dispersed on ZrO 2 crystals represents an effective and robust catalyst for the industrially relevant oxidation of HCl to chlorine. Remarkably, the catalytic performance increases significantly during the first 80 h on stream and remains stable thereafter. According to XRD results, this self‐activation of the catalyst is accompanied by the disappearance of the starting α‐U 3 O 8 phase. The uranium distribution on the ZrO 2 crystals at different stages of the reaction was visualized by aberration‐corrected HAADF‐STEM. The mostly mono‐atomic uranium oxide layers present in the fresh catalyst broaden during reaction and often form a homogeneous coating over the support crystals comprising small uranium oxide species mostly comprising a single uranium atom. These species are found to be often located on top of columns of ZrO 7 polyhedra, pointing to a strong fixation on the carrier. This observation likely explains the unique stability of the zirconia‐supported uranium oxide catalyst in the Deacon reaction.