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Unité de Formation et de Recherche de Chimie

Séminaire de Yoji Kobayashi le 18 mai 2015

Séminaire de  Yoji Kobayashi, Department of Energy & Hydrocarbon Chemistry,
Graduate School of Engineering, Kyoto University le Lundi 18 Mai Salle Raphaël 2-3 14 Heure

"Ammonia synthesis from the oxyhydride BaTiO3-xHx"
The titanate perovskite oxyhydrides (Ba, Sr, Ca)TiO2.5H0.5 are a new class of materials that we have
recently discovered. Here, hydrogen is present in the hydride (H–) form and in solid solution with
O2–, as opposed to being in protonic form. Using a combination of isotope analysis, neutron/X-ray
diffraction, and other techniques, we find that these oxyhydrides can activate various small
molecules, including H2 and N2 and further exchange or incorporate them as H–/N3– within the
oxide lattice.
Based on this reactivity with H2 and N2, we investigated the use of BaTiO2.5H0.5 as a catalyst
material for ammonia synthesis under moderate Haber-Bosch conditions. When BaTiO2.5H0.5 is
used as a support material for Ru or Fe particles, we find a very large increase in activity due to the
presence of hydride. The activity is on par with, or surpasses that of other known catalysts. Even
without any supported metal, a small amount of ammonia is produced, signifying the non-innocent
character of the support.
The effect of hydride within the lattice influences Ru and Fe in different ways, in terms of
activation energy, reaction order, and overall activity. We find strong evidence of the participation
of lattice hydrogen in the catalytic cycle, and nitrogen is also incorporated into the oxyhydride
lattice. H– may also drastically increase the surface basicity of the support, leading to N2 activation.
This talk will present the current status of our work in investigating how this new catalyst material

Alain Frigara - 08/02/16

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