Parahydrogen-induced polarization (PHIP) in heterogeneous hydrogenation over bulk metals and metal oxides

2014 ◽  
Vol 50 (7) ◽  
pp. 875-878 ◽  
Author(s):  
Kirill V. Kovtunov ◽  
Danila A. Barskiy ◽  
Oleg G. Salnikov ◽  
Alexander K. Khudorozhkov ◽  
Valery I. Bukhtiyarov ◽  
...  
Keyword(s):  
Metal Oxides ◽  
Induced Polarization ◽  
Heterogeneous Hydrogenation

para-Hydrogen-Induced Polarization in Heterogeneous Hydrogenation Reactions

2007 ◽  
Vol 129 (17) ◽  
pp. 5580-5586 ◽  
Author(s):  
Igor V. Koptyug ◽  
Kirill V. Kovtunov ◽  
Scott R. Burt ◽  
M. Sabieh Anwar ◽  
Christian Hilty ◽  
...  
Keyword(s):  
Induced Polarization ◽  
Para Hydrogen ◽  
Hydrogenation Reactions ◽  
Heterogeneous Hydrogenation

Observation of Parahydrogen-Induced Polarization in Heterogeneous Hydrogenation on Supported Metal Catalysts

2008 ◽  
Vol 120 (8) ◽  
pp. 1514-1517 ◽  
Author(s):  
Kirill V. Kovtunov ◽  
Irene E. Beck ◽  
Valery I. Bukhtiyarov ◽  
Igor V. Koptyug
Keyword(s):  
Metal Catalysts ◽  
Induced Polarization ◽  
Supported Metal Catalysts ◽  
Heterogeneous Hydrogenation ◽  
Supported Metal

Heterogeneous hydrogenation of phenylalkynes with parahydrogen: hyperpolarization, reaction selectivity, and kinetics

2019 ◽  
Vol 21 (48) ◽  
pp. 26477-26482 ◽  
Author(s):  
Ekaterina V. Pokochueva ◽  
Kirill V. Kovtunov ◽  
Oleg G. Salnikov ◽  
Max E. Gemeinhardt ◽  
Larisa M. Kovtunova ◽  
...  
Keyword(s):  
Induced Polarization ◽  
Reaction Selectivity ◽  
Powerful Technique ◽  
Liquid Phases ◽  
Hydrogenation Reactions ◽  
Heterogeneous Hydrogenation

Parahydrogen-induced polarization (PHIP) is a powerful technique for studying hydrogenation reactions in both gas and liquid phases.

Observation of Parahydrogen-Induced Polarization in Heterogeneous Hydrogenation on Supported Metal Catalysts

2008 ◽  
Vol 47 (8) ◽  
pp. 1492-1495 ◽  
Author(s):  
Kirill V. Kovtunov ◽  
Irene E. Beck ◽  
Valery I. Bukhtiyarov ◽  
Igor V. Koptyug
Keyword(s):  
Metal Catalysts ◽  
Induced Polarization ◽  
Supported Metal Catalysts ◽  
Heterogeneous Hydrogenation ◽  
Supported Metal

scholarly journals Pd-based bimetallic catalysts for parahydrogen-induced polarization in heterogeneous hydrogenations

2021 ◽  
Vol 2 (1) ◽  
pp. 93-103
Author(s):  
Dudari B. Burueva ◽  
Aleksandr Y. Stakheev ◽  
Igor V. Koptyug
Keyword(s):  
Bimetallic Catalysts ◽  
Heterogeneous Catalysts ◽  
Induced Polarization ◽  
In Vivo Studies ◽  
Catalytically Active ◽  
Spin Isomers ◽  
Heterogeneous Hydrogenation ◽  
H2 Addition ◽  
Free Gases

Abstract. Production of hyperpolarized catalyst-free gases and liquids by heterogeneous hydrogenation with parahydrogen can be useful for various technical as well as biomedical applications, including in vivo studies, investigations of mechanisms of industrially important catalytic processes, enrichment of nuclear spin isomers of polyatomic gases, and more. In this regard, the wide systematic search for heterogeneous catalysts effective in pairwise H2 addition required for the observation of parahydrogen-induced polarization (PHIP) effects is crucial. Here in this work we demonstrate the competitive advantage of Pd-based bimetallic catalysts for PHIP in heterogeneous hydrogenations (HET-PHIP). The dilution of catalytically active Pd with less active Ag or In atoms provides the formation of atomically dispersed Pd1 sites on the surface of Pd-based bimetallic catalysts, which are significantly more selective toward pairwise H2 addition compared to the monometallic Pd. Furthermore, the choice of the dilution metal (Ag or In) has a pronounced effect on the efficiency of bimetallic catalysts in HET-PHIP, as revealed by comparing Pd-Ag and Pd-In bimetallic catalysts.

HREM Study of electron-induced surface radiation damage in ReO3

1991 ◽  
Vol 49 ◽  
pp. 636-637
Author(s):  
R. Ai ◽  
H.-J. Fan ◽  
L. D. Marks
Keyword(s):  
Transition Metal ◽  
Metal Ions ◽  
Metal Oxides ◽  
Electron Irradiation ◽  
Transition Metal Oxides ◽  
Carbon Film ◽  
Transition Metal Ions ◽  
Surface Radiation ◽  
Valence Transition ◽  
Electron Microscopes

It has been known for a long time that electron irradiation induces damage in maximal valence transition metal oxides such as TiO2, V2O5, and WO3, of which transition metal ions have an empty d-shell. This type of damage is excited by electronic transition and can be explained by the Knoteck-Feibelman mechanism (K-F mechanism). Although the K-F mechanism predicts that no damage should occur in transition metal oxides of which the transition metal ions have a partially filled d-shell, namely submaximal valence transition metal oxides, our recent study on ReO3 shows that submaximal valence transition metal oxides undergo damage during electron irradiation.ReO3 has a nearly cubic structure and contains a single unit in its cell: a = 3.73 Å, and α = 89°34'. TEM specimens were prepared by depositing dry powders onto a holey carbon film supported on a copper grid. Specimens were examined in Hitachi H-9000 and UHV H-9000 electron microscopes both operated at 300 keV accelerating voltage. The electron beam flux was maintained at about 10 A/cm2 during the observation.

Problems with oxygen analysis in the system MgO-Al2O3-SiO2 with the electron microprobe

1992 ◽  
Vol 50 (2) ◽  
pp. 1624-1625
Author(s):  
Michel Fialin ◽  
Guy Rémond
Keyword(s):  
Transition Metal ◽  
Metal Oxides ◽  
Transition Metal Oxides ◽  
Electrostatic Charge ◽  
Carbon Layer ◽  
Sample Holder ◽  
Rock Matrix ◽  
Electrical Discharges ◽  
Thin Carbon ◽  
Beam Instabilities

Oxygen-bearing minerals are generally strong insulators (e.g. silicates), or if not (e.g. transition metal oxides), they are included within a rock matrix which electrically isolates them from the sample holder contacts. In this respect, a thin carbon layer (150 Å in our laboratory) is evaporated on the sections in order to restore the conductivity. For silicates, overestimated oxygen concentrations are usually noted when transition metal oxides are used as standards. These trends corroborate the results of Bastin and Heijligers on MgO, Al2O3 and SiO2. According to our experiments, these errors are independent of the accelerating voltage used (fig.l).Owing to the low density of preexisting defects within the Al2O3 single-crystal, no significant charge buildup occurs under irradiation at low accelerating voltage (< 10keV). As a consequence, neither beam instabilities, due to electrical discharges within the excited volume, nor losses of energy for beam electrons before striking the sample, due to the presence of the electrostatic charge-induced potential, are noted : measurements from both coated and uncoated samples give comparable results which demonstrates that the carbon coating is not the cause of the observed errors.

METAL-OXIDES COMPOSITES FOR BaFe12O19 PERMANENT MAGNETS

1977 ◽  
Vol 38 (C1) ◽  
pp. C1-333-C1-336 ◽  
Author(s):  
P. CAVALLOTTI ◽  
R. ROBERTI ◽  
G. CAIRONI ◽  
G. ASTI
Keyword(s):  
Metal Oxides ◽  
Permanent Magnets
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