Preparation of Mo nanopowders through hydrogen reduction of a combustion synthesized foam-like MoO2 precursor

Gu, Siyong; Qin, Mingli; Zhang, Houan; Ma, Jiawei; Qu, Xuanhui

doi:10.1016/j.ijrmhm.2018.05.015

Cited by 19 publications

(5 citation statements)

References 26 publications

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“…On the basis of these peaks, the contents of MoO 2 , MoO 3 , and Mo 4 O 11 were calculated, and the results are listed in Table 2. As shown, the contents of impurities, such as MoO 3 and Mo 4 O 11 , were found to be quite high, which far exceeds that indicated by the Rietveld refinement XRD result of a previous study by our research group [27]. This result can be related to the XPS technique, which can analyze only the surface with an information depth of up to 10 nm and can be affected by surface oxidation of the MoO 2 nanoparticles.…”

Section: Resultsmentioning

confidence: 54%

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Fabrication of La2O3 Uniformly Doped Mo Nanopowders by Solution Combustion Synthesis Followed by Reduction under Hydrogen

Qin

Zhang

et al. 2018

Materials

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This work reports the preparation of La2O3 uniformly doped Mo nanopowders with the particle sizes of 40–70 nm by solution combustion synthesis and subsequent hydrogen reduction (SCSHR). To reach this aim, the foam-like MoO2 precursors (20–40 nm in size) with different amounts of La2O3 were first synthesized by a solution combustion synthesis method. Next, these precursors were used to prepare La2O3 doped Mo nanopowders through hydrogen reduction. Thus, the content of La2O3 used for doping can be accurately controlled via the SCSHR route to obtain the desired loading degree. The successful doping of La2O3 into Mo nanopowders with uniform distribution were proved by X-ray photon spectroscopy and transmission electron microscopy. The preservation of the original morphology and size of the MoO2 precursor by the La2O3 doped Mo nanopowders was attributed to the pseudomorphic transport mechanism occurring at 600 °C. As shown by X-ray diffraction, the formation of Mo2C impurity, which usually occurs in the direct H2 reduction process, can be avoided by using the Ar calcination-H2 reduction process, when residual carbon is removed by the carbothermal reaction during Ar calcination at 500 °C.

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Section: Resultsmentioning

confidence: 54%

“…At 600 °C, Equation (5) takes place, forming metallic Mo nanoparticles. Furthermore, an insignificant amount of Mo 2 C impurity formed as a result of the carbothermal reduction in hydrogen of MoO 2 [27,30,31], as shown by Equation (6). La 2 O 3 does not undergo any phase transition due to its high thermodynamic stability.…”

Section: Resultsmentioning

confidence: 99%

Fabrication of La2O3 Uniformly Doped Mo Nanopowders by Solution Combustion Synthesis Followed by Reduction under Hydrogen

Qin

Zhang

et al. 2018

Materials

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“…Kanga et al [23] prepared nanosized W and W-Ni powders by applying ball milling and a hydrogen reduction of oxide powders. Gua et al [24] prepared Mo nanopowders through a hydrogen reduction of a combustion-synthesized foam-like MoO 2 precursor. All of the above studies are based on a reducing substance pretreatment, which provides a certain reference experience for this study.…”

Section: Chemical Reaction Considerationsmentioning

confidence: 99%

Reaction Mechanism and Process Control of Hydrogen Reduction of Ammonium Perrhenate

Tang

Sun

Zhang

et al. 2020

Metals

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The preparation of rhenium powder by a hydrogen reduction of ammonium perrhenate is the only industrial production method. However, due to the uneven particle size distribution and large particle size of rhenium powder, it is difficult to prepare high-density rhenium ingot. Moreover, the existing process requires a secondary high-temperature reduction and the deoxidization process is complex and requires a high-temperature resistance of the equipment. Attempting to tackle the difficulties, this paper described a novel process to improve the particle size distribution uniformity and reduce the particle size of rhenium powder, aiming to produce a high-density rhenium ingot, and ammonium perrhenate is completely reduced by hydrogen at a low temperature. When the particle size of the rhenium powder was 19.74 µm, the density of the pressed rhenium ingot was 20.106 g/cm3, which was close to the theoretical density of rhenium. In addition, the hydrogen reduction mechanism of ammonium perrhenate was investigated in this paper. The results showed that the disproportionation of ReO3 decreased the rate of the reduction reaction, and the XRD and XPS patterns showed that the increase in the reduction temperature was conducive to increasing the reduction reaction rate and reducing the influence of disproportionation on the reduction process. At the same reduction temperature, reducing the particle sizes of ammonium perrhenate was conducive to increasing the hydrogen reduction rate and reducing the influence of the disproportionation.

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“…[ 11 , 12 , 13 , 14 ]. Mo nano-powders can be prepared by many methods such as high-energy ball milling, electric explosion, and other complex chemical reaction methods [ 15 , 16 , 17 , 18 , 19 ]. However, most of these methods require complicated procedures and cannot be used for industrial-scale mass production.…”

Section: Introductionmentioning

confidence: 99%

Controllable Preparation of Spherical Molybdenum Nano-Powders by One-Step Reduction of APM in Radio Frequency Hydrogen Plasma

Wang

Chen

et al. 2022

Materials

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Spherical molybdenum nano-powders were in-situ ultrafast synthesized from ammonium paramolybdate (APM) raw materials in a one-step reduction method by radio frequency (RF) hydrogen plasma. Due to the extreme conditions of the RF plasma torch such as its high temperature and large temperature gradient, the injected raw APM powder was quickly gasified and then reduced into nano-sized metal molybdenum (Mo) powder. The influences of APM powder delivery rate and H2 concentration on the properties of the obtained powders were investigated. Field-emission scanning electron microscope (FESEM), transmission electron microscope (TEM), X-ray diffraction (XRD), nanolaser particle analyzer, and specific surface area method were used to characterize the morphology, phase, and particle size distribution of the powders. The results showed that the nano-sized Mo powder obtained by hydrogen plasma treatment had a quasi-spherical morphology and an average particle size of about 30 nm. The particle size could be successfully adjusted by varying H2 concentrations. In addition, spherical nano-sized MoO3 powder could be obtained when no H2 was added into the RF plasma.

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Preparation of Mo nanopowders through hydrogen reduction of a combustion synthesized foam-like MoO2 precursor

Cited by 19 publications

References 26 publications

Fabrication of La2O3 Uniformly Doped Mo Nanopowders by Solution Combustion Synthesis Followed by Reduction under Hydrogen

Fabrication of La2O3 Uniformly Doped Mo Nanopowders by Solution Combustion Synthesis Followed by Reduction under Hydrogen

Reaction Mechanism and Process Control of Hydrogen Reduction of Ammonium Perrhenate

Controllable Preparation of Spherical Molybdenum Nano-Powders by One-Step Reduction of APM in Radio Frequency Hydrogen Plasma

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