From ammonium Hexahalorhenates(IV) to nanocrystalline rhenium metal: A combined thermal, diffraction and microscopic analysis

Louis–Jean, James; George, Jonathan; Poineau, Frédéric

doi:10.1016/j.ijrmhm.2022.105840

Cited by 4 publications

(3 citation statements)

References 61 publications

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“…However, simultaneous reduction proceeded of the structures formed in potassium pres-ence as K(ReO4) and surface K-Co-Re-O-(Al). As reported, perrhenate salt is converted to rhenium oxides at 350 • C [35]. Nevertheless, the reduction ends at 620 • C, analogous to the CoRe system.…”

Section: Temperature-programmed Reductionsupporting

confidence: 51%

Catalytic Ability of K- and Co-Promoted Oxo-Re and Oxo-ReMo Nanosized Compositions for Water–Gas Shift Reaction

Nikolova,

Ivanov,

Vakros

et al. 2023

Catalysts

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The water–gas shift (WGS) reaction (CO + H2O ↔ CO2 + H2) plays an important role in the hydrogen economy because it is an effective way to reduce the carbon release to net-zero CO2 emissions. The general goal of this research is to develop nanosized oxo-rhenium catalyst formulations promoted by K and Co components for the WGS process. Rhenium, as a low-cost catalyst component, is a good choice compared to platinum group metals. A surface density of 2 Re atoms/nm2 on a γ-Al2O3 support as well as cobalt (3 wt.% CoO) and potassium (5 wt.% K2O) amounts were chosen to match the composition of our own active sour WGS KCoRe catalyst developed some years ago. An initial evaluation of the impact of replacing half of the rhenium with molybdenum, which is more affordable, was also studied. The purpose of this study is to explore the catalytic ability of CoRe, K-CoRe, CoReMo, and K-CoReMo formulations in the WGS reaction and elucidate the effect of a CO/Ar reaction mixture used in an activation–reduction pretreatment to form active catalyst structures. Oxo-K-Co-Re(Mo) entities formed in synthesized samples and their reducibility were analyzed via several physicochemical methods, such as N2 physisorption, PXRD, UV-vis DRS, and H2-TPR. In summary, the selected potassium- and cobalt-promoted Re-containing formulations have potential as catalysts for the classical WGS reaction. The selection of an appropriate procedure for activation–reduction, involving the reducing gas (CO or H2), temperature, and duration, was needed for tuning the K-CoRe catalyst’s high activity for the WGS reaction with structural stability and longevity.

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Section: Temperature-programmed Reductionsupporting

confidence: 51%

Catalytic Ability of K- and Co-Promoted Oxo-Re and Oxo-ReMo Nanosized Compositions for Water–Gas Shift Reaction

Nikolova,

Ivanov,

Vakros

et al. 2023

Catalysts

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“…The enhanced crystallinity leads to structural variation, including the change of grain and strains inside the crystalline region. To examine such variance, the average crystallite size G s , microstrain ε, dislocations (δ), number of crystallites (N) were calculated for the major phase (Fe 2 O 3 ) via Scherer's Equation [51][52][53]:…”

Section: X-ray Analysismentioning

confidence: 99%

Microstructure, electrical, optical and electrochemical characteristics of silver phosphate glasses cathode for magnesium battery applications

Khalil

Hameed²,

Farrag³

et al. 2022

J. Phys. D: Appl. Phys.

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The realization of a practical magnesium battery is combined with the development of a high kinetic cathode and compatible electrolyte to facilitate the redox process. For this reason, silver phosphate glasses in the binary system (Fe2O3-AgPO3) are prepared using the conventional quenching method. The glasses were defined in the form [Fe2O3]x[AgPO3](100-x) and the composition with 0  x  40 wt. %. The molar volumes and densities were measured. These glass systems were characterized using XRD, FTIR spectroscopy, UV–Vis-NIR spectrophotometer, electrochemical procedures and impedance spectroscopy. X-ray diffraction revealed that pristine AgPO3 sample was formed in a glassy state, whereas two crystalline phases (AgFeP2O7 and Fe2O3) were formed after the incorporation of Fe2O3 by different concentrations. Bond assignments associated with different functional groups were investigated by an FT-IR spectroscopy. The values of the band gap were decreased with the increase of Fe2O3 content. The effect of grains and grain boundaries in a heterostructure made up of Fe2O3 and AgFeP2O7 crystallites grown in silver phosphate glasses was studied using impedance spectroscopy. The complex impedance, electrical conductivity, and complex electric modulus were measured in terms of frequency and temperature dependency in [Fe2O3]x-[AgPO3](1-x). In the studied glass systems, non-Debye relaxation was observed. Under a variable regime, ac conductivity follows a modified Jonscher's law Arrhenius fitting of multiple relaxation processes in the material yielded activation energy of (0.12 eV–0.271 eV) which support a Maxwell–Wagner relaxation model in the heterostructure glasses at high temperatures and low frequencies. The dc conductivity decreases with iron rate and follows the Arrhenius law with very low activation energy (0.12–0.27 eV. Mg//electrolyte//Glass coin cells are assembled and show an initial discharge capacity of up to ∼564 mAh/g. These materials are attractive for application in modernistic electrochemical devices because of their great compositional and preparation variety which enables tuning the types and techniques of electrical conduction in the material.

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“…In the course of the operation of molten-salt reactors, the TcHal 6 2– compounds will inevitably accumulate. The study of the crystal structure, intermolecular interactions and conditions for the formation of technetium hexahalides can be used to develop methods for reprocessing fuel for new types of reactors [ 18 , 19 ]. It should be taken into account that TcHal 6 2– compounds can be used to purify and obtain metallic technetium, which is considered to be the most acceptable form for the long-term storage or transmutation of technetium.…”

Section: Introductionmentioning

confidence: 99%

Novel Synthesis Methods of New Imidazole-Containing Coordination Compounds Tc(IV, V, VII)—Reaction Mechanism, Xrd and Hirshfeld Surface Analysis

Volkov

Novikov

Grigoriev

et al. 2022

IJMS

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In this work, we have proposed two new methods for the synthesis of [TcO2L4]+ (where L = imidazole (Im), methylimidazole (MeIm)) complexes using thiourea (Tu) and Sn(II) as the reducing agents. The main and by-products of the reactions were determined, and possible reaction mechanisms were proposed. We have shown that the reduction of Tc(VII) with thiourea is accompanied by the formation of the Tc(III) intermediate and further oxidation to Tc(V). The reaction conditions’ changing can lead to the formation of Tc(VII) and Tc(IV) salts. Seven new crystal structures are described in this work: Tc(V) complexes, salts with Tc(VII) and Tc(IV) anions. For the halide salts of Tu the cell parameters were determined. In all of the obtained compounds, except for [TcO2(MeIm)4]TcO4, there are π–stacking interactions between the aromatic rings. An increase in the anion size lead to weakening of the intermolecular interactions. The halogen bonds and anion-π interactions were also found in the hexahalide-containing compounds. The Hirshfeld surface analysis showed that the main contribution to the crystal packing is created by the van der Waals interactions of the H···H type (42.5–55.1%), H···C/C ···H (17.7–21.3%) and hydrogen bonds, which contribute 15.7–25.3% in total.

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From ammonium Hexahalorhenates(IV) to nanocrystalline rhenium metal: A combined thermal, diffraction and microscopic analysis

Cited by 4 publications

References 61 publications

Catalytic Ability of K- and Co-Promoted Oxo-Re and Oxo-ReMo Nanosized Compositions for Water–Gas Shift Reaction

Catalytic Ability of K- and Co-Promoted Oxo-Re and Oxo-ReMo Nanosized Compositions for Water–Gas Shift Reaction

Microstructure, electrical, optical and electrochemical characteristics of silver phosphate glasses cathode for magnesium battery applications

Novel Synthesis Methods of New Imidazole-Containing Coordination Compounds Tc(IV, V, VII)—Reaction Mechanism, Xrd and Hirshfeld Surface Analysis

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