Direct Neutron Spectroscopy Observation of Cerium Hydride Species on a Cerium Oxide Catalyst.

Title Direct Neutron Spectroscopy Observation of Cerium Hydride Species on a Cerium Oxide Catalyst.
Authors Z. Wu; Y. Cheng; F. Tao; L. Daemen; G.Shiou Foo; L. Nguyen; X. Zhang; A. Beste; A.J. Ramirez-Cuesta
Journal J Am Chem Soc
DOI 10.1021/jacs.7b05492
Abstract

Ceria has recently shown intriguing hydrogenation reactivity in catalyzing alkyne selectively to alkenes. However, the mechanism of the hydrogenation reaction, especially the activation of H2, remains experimentally elusive. In this work, we report the first direct spectroscopy evidence for the presence of both surface and bulk Ce-H species upon H2 dissociation over ceria via in situ inelastic neutron scattering spectroscopy. Combined with in situ ambient-pressure X-ray photoelectron spectroscopy, IR, and Raman spectroscopic studies, the results together point to a heterolytic dissociation mechanism of H2 over ceria, leading to either homolytic products (surface OHs) on a close-to-stoichiometric ceria surface or heterolytic products (Ce-H and OH) with the presence of induced oxygen vacancies in ceria. The finding of this work has significant implications for understanding catalysis by ceria in both hydrogenation and redox reactions where hydrogen is involved.

Citation Z. Wu; Y. Cheng; F. Tao; L. Daemen; G.Shiou Foo; L. Nguyen; X. Zhang; A. Beste; A.J. Ramirez-Cuesta.Direct Neutron Spectroscopy Observation of Cerium Hydride Species on a Cerium Oxide Catalyst.. J Am Chem Soc. 2017;139(28):97219727. doi:10.1021/jacs.7b05492

Related Elements

Cerium

See more Cerium products. Cerium (atomic symbol: Ce, atomic number: 58) is a Block F, Group 3, Period 6 element with an atomic weight of 140.116. The number of electrons in each of cerium's shells is 2, 8, 18, 19, 9, 2 and its electron configuration is [Xe]4f2 6s2. Cerium Bohr ModelThe cerium atom has a radius of 182.5 pm and a Van der Waals radius of 235 pm. In its elemental form, cerium has a silvery white appearance. Cerium is the most abundant of the rare earth metals. It is characterized chemically by having two valence states, the +3 cerous and +4 ceric states. The ceric state is the only non-trivalent rare earth ion stable in aqueous solutions. Elemental CeriumIt is therefore strongly acidic and oxidizing, in addition to being moderately toxic.The cerous state closely resembles the other trivalent rare earths. Cerium is found in the minerals allanite, bastnasite, hydroxylbastnasite, monazite, rhabdophane, synchysite and zircon. Cerium was discovered by Martin Heinrich Klaproth, Jöns Jakob Berzelius, and Wilhelm Hisinger in 1803 and first isolated by Carl Gustaf Mosander in 1839. The element was named after the asteroid Ceres, which itself was named after the Roman god of agriculture.

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