title: Highly Ordered Mesoporous Cobalt-Containing Oxides: Structure, Catalytic Properties, and Active Sites in Oxidation of Carbon Monoxide.
abstract: Co3O4 with a spinel structure is a very active oxide catalyst for the oxidation of CO. In such catalysts, octahedrally coordinated Co(3+) is considered to be the active site, while tetrahedrally coordinated Co(2+) is assumed to be basically inactive. In this study, a highly ordered mesoporous CoO has been prepared by H2 reduction of nanocast Co3O4 at low temperature (250 °C). The as-prepared CoO material, which has a rock-salt structure with a single Co(2+) octahedrally coordinated by lattice oxygen in Fm3̅m symmetry, exhibited unexpectedly high activity for CO oxidation. Careful investigation of the catalytic behavior of mesoporous CoO catalyst led to the conclusion that the oxidation of surface Co(2+) to Co(3+) causes the high activity. Other mesoporous spinels (CuCo2O4, CoCr2O4, and CoFe2O4) with different Co species substituted with non/low-active metal ions were also synthesized to investigate the catalytically active site of cobalt-based catalysts. The results show that not only is the octahedrally coordinated Co(3+) highly active but also the octahedrally coordinated Co(2+) species in CoFe2O4 with an inverse spinel structure shows some activity. These results suggest that the octahedrally coordinated Co(2+) species is easily oxidized and shows high catalytic activity for CO oxidation.
authors: Max-Planck-Institut für Kohlenforschung , Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany.
authors: Dong
authors: D
authors: Gu
authors: Max-Planck-Institut für Kohlenforschung , Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany.|Key Lab for Colloid and Interface Chemistry, School of Chemistry and Chemical Engineering, Shandong University , Jinan 250100, People's Republic of China.
authors: Chun-Jiang
authors: CJ
authors: Jia
authors: Max-Planck-Institut für Kohlenforschung , Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany.
authors: Claudia
authors: C
authors: Weidenthaler
authors: Max-Planck-Institut für Kohlenforschung , Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany.
authors: Hans-Josef
authors: HJ
authors: Bongard
authors: Max-Planck-Institut für Kohlenforschung , Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany.
authors: Bernd
authors: B
authors: Spliethoff
authors: Max-Planck-Institut für Kohlenforschung , Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany.
authors: Wolfgang
authors: W
authors: Schmidt
authors: Max-Planck-Institut für Kohlenforschung , Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany.
authors: Ferdi
authors: F
authors: Schüth