CATALYSIS TODAY
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2024
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IF 5.2
Qian Qiang,Huamei Yang,Wentao Su,Haiyan He,Shenglong Tian,Changzhi Li,Tao Zhang
Lignin is the most abundant renewable resource composed of aromatic moieties in nature. The highlight aromatic characteristics of lignin renders it a sustainable feedstock for aromatic chemicals and naphthene fuels. Tungsten is a typical rare metal for the synthesis of non-noble metal catalysts which show potential in catalyzing lignin depolymerization/valorization. This review highlights the latest advances in the application of tungsten-based catalysts for the transformation of lignin into value-added chemicals and fuels. We focus on the synthesis and application of tungsten carbides , tungsten sulfide, tungsten phosphide, tungsten acids, and tungsten-based bimetallic catalysts on lignin conversion. Among them, tungsten carbides are extensively summarized. Perspectives for the future investigation on the lignin depolymerization are also presented.
研究领域:
化学工程
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可再生资源利用
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产品关联
DOI
高影响因子
INTERNATIONAL JOURNAL OF REFRACTORY METALS & HARD MATERIALS
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2018
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IF 2.606
Yijie Wu,Jie Dang,Zepeng Lv,Run Zhang
In the present study, a new and simple method to prepare tungsten and tungsten carbides powders was proposed by using WO 3 powders as the raw material and CH 3 OH vapor as the reduction and carbonization agent. Both thermodynamic and experimental studies were carried out, and based on the results, the reaction routes were obtained. It was found that at low and moderate temperatures, the final product of WC was formed via intermediates of W 18 O 49 , WO 2 , partial metallic W and W 2 C; while at high temperature, WO 3 was first reduced to WO 2 with the intermediate phase of W 18 O 49 , and then reduced to W. The morphology of final products almost retained the same shape as that of raw materials WO 3 at low temperature, however, the large particles with blocky shape disappeared and the products were all small W particles with polyhedral shape at high temperature. Furthermore, the reaction mechanisms were proposed: the pseudomorphic transformation mechanism dominated the reaction at low temperature, but at high temperature, the reduction obeyed the chemical vapor transport mechanism, which is beneficial for grain refining of final product.
研究领域:
材料科学
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化学工程
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产品关联
DOI
高影响因子
Journal of Cleaner Production
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2018
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IF 5.651
Leiting Shen,Xiaobin Li,Qiusheng Zhou,Zhihong Peng,Guihua Liu,Tiangui Qi,Pekka Taskinen
To directly obtain solution of (NH 4 ) 2 WO 4 instead of Na 2 WO 4 is the key for developing a cleaner technology of ammonium paratungstate production. In this paper, ammoniacal ammonium carbonate solution was adopted for leaching tungsten from the converted product, a mixture of H 2 WO 4 and CaSO 4 obtained by treating scheelite with sulfuric acid . The research indicates that tungsten can be efficiently extracted in form of ammonium tungstate solution with WO 3 leaching yield of >99.5% under moderate leaching conditions. The WO 3 leaching yield is influenced by the transformation of calcium sulfate to calcium carbonate due to forming CaWO 4 through the secondary reaction between CaSO 4 and (NH 4 ) 2 WO 4 , whereas an excess (NH 4 ) 2 CO 3 (≥0.64 mol/L) can suppress the secondary reaction by facilitating the transformation. Additionally, the consumed ammonium carbonate can be recovered by treating the leaching residue with ammonium sulfate solution at above 70 °C. This work presents a cleaner and sustainable technique for producing ammonium paratungstate, with circulating the leaching reagents and bypassing the conversion of Na 2 WO 4 to (NH 4 ) 2 WO 4 .
研究领域:
化学工程
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材料科学
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环境科学
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产品关联
DOI
高影响因子
CHEMICAL GEOLOGY
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2019
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IF 3.618
Xiaolin Wang,Ye Qiu,Jianjun Lu,I-Ming Chou,Wenlan Zhang,Guanglai Li,Wenxuan Hu,Zhen Li,Richen Zhong
Knowledge on hydrothermal tungsten (W) species is vital towards a better understanding of tungsten transport and mineralization mechanisms. In this study, in situ Raman spectra of a 0.005 – 0.1 mol/kg ( m ) K 2 WO 4 solution containing CO 2 , HCl, and NaHCO 3 were collected at 50–400 °C and 20–60 MPa. The spectra for the symmetric stretching vibration mode of the W O bond, v 1 (W O), were analyzed to investigate the hydrothermal tungstate species. Results showed that carbonate/bicarbonate do not associate with tungstate to form carbonic tungstate species. Nevertheless, the presence of CO 2 can increase the fluid acidity, which favors the formation of polymeric tungstate species at <300 °C. Above about 300 °C, monomeric tungstates (e.g., WO 4 2- , HWO 4 -, H 2 WO 4 and alkali tungstate ion pairs) are responsible for the hydrothermal transport of tungsten, and the v 1 (W O) modes of these species are centered at ∼930 cm -1 and 950 cm -1 . Based on the above observations, we simulated the mineralization process in the context of fluid-rock interactions using tungstate and alkali tungstate ion pairs as the only aqueous W species. The thermodynamic simulations showed that (a) the timing of mineralization mainly depends on the W concentration in the initial mineralizing fluid and the availability of Ca 2+ , Fe 2+ and Mn 2+ , with higher W concentrations generally favoring higher temperature mineralization; (b) highly W-enriched fluid is not essential for W mineralization, while extremely low contents of Fe, Mn and Ca in the magma are useful to maintain the mobility of aqueous W until favorable host rocks are encountered; and (c) a “hydrogen reservoir” effect was identified for dissolved CO 2 . The presence of CO 2 can promote the extraction of Fe(II) from the pelitic host rocks, thereby facilitating a high-grade vein-type W mineralization. At <∼300 °C, polytungstate species, whose v 1 (W O) modes are centered at ∼965 – 995 cm -1 , are important hydrothermal W species along with monomeric tungstates. Therefore, polymeric tungstate species should be considered in future thermodynamic modeling of W transport and mineralization at <300 °C. An increase in fluid pH induced by CO 2 -escape and/or fluid-rock interactions will destabilize the polymeric tungstates to form WO 4 2- and other monomeric tungstate, which interacts with metal cations to form wolframite and/or scheelite.
研究领域:
地球化学
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矿物学
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产品关联
DOI
高影响因子
Materials Today Communications
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2024
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IF 3.7
Yuhui Chen,Zhenhua Hao,Rulong Ma,Pei Wang,Yongchun Shu,Jilin He
In this study, a new unmixed carbon reduction method was proposed for the preparation of pure W powder. The effects of reduction temperature, reduction time, carbon distance and thickness of WO 3 layer on the phase of the reduction products were investigated. Results show that pure tungsten powder with a carbon content of less than 150 ppm can be prepared at 950 °C with a WO 3 layer thickness of 5 mm and a carbon distance of 2 mm. Increased carbon distance and thickness of WO 3 layer will lead to a decrease in the reduction ratio. Additionally, particle size of the tungsten powder gradually increases from 1 μm to 8 μm due to sintering with the extended reduction time. Furthermore, a two-stage carbon reduction process with WO 2 as an intermediate product is proposed, which avoids the sintering and growth of tungsten powder particles and the particle size of tungsten powder was successfully reduced to 2 μm. This unmixed carbon reduction reduces the carbon concentration and prevents the carbonization of tungsten powder. The experiment verifies the feasibility of carbon as a reducing agent in producing pure tungsten powder by reducing WO 3 .
研究领域:
材料科学
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冶金学
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产品关联
DOI
高影响因子
HYDROMETALLURGY
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2017
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IF 2.605
Yulong Liao,Zhongwei Zhao
A sulfuric-phosphoric acid leaching process for scheelite was developed. In the process, tungsten exists as a soluble phosphotungstic acid in the leachate. Thus, extracting tungsten from the solution is necessary. Considering the advantages of solvent extraction with oxygen-containing solvents, 2-octanol and tri-butyl phosphate (TBP) were employed to extract tungsten from phosphotungstic-sulfuric acid solutions. The impacts of phosphoric acid and ageing time on the extraction were primarily investigated. It was determined that for H 3 PW 12 O 40 solution with high H 2 SO 4 (49.71 g/L S) content, the WO 3 content in raffinates remained as low as 0.01 g/L after a single stage extraction even if the ageing time increased. However, if such solution contained high H 3 PO 4 (113.95 g/L P), the remaining WO 3 content increased to approximately 0.29 g/L after aged for 0.5 h. And, it further increased to 1.06 and 2.16 g/L after ageing for 24 h and 14 days. It indicated that phosphoric acid and ageing time played an anti-synergistic effect on the extraction. Furthermore, for the solution with abundant H 3 PO 4 aged for 0.5 h, the 31 P NMR results showed there were only the characteristic peak of H 3 PW 12 O 40 ( δ = − 16.24 ppm) and the peak of H 3 PO 4 ( δ = − 0.96 ppm). However, an unknown peak ( δ = − 2.80 ppm) appeared in the spectrum of such solution aged for two weeks and that of its raffinate. This finding implies that the combination reaction between phosphoric and phosphotungstic acid creates another species that is difficult to extract. Therefore, to obtain satisfactory extraction efficiency, the dosage of phosphoric acid should be controlled during the mineral decomposition stage.
研究领域:
冶金学
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化学工程
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产品关联
DOI
高影响因子
Journal of Materials Research and Technology-JMR&T
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2020
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IF 5.289
Zepeng Lv,Yijie Wu,Jie Dang,Dong Liu,Liwen Hu,Kaiping Du,Haibo Sun
The effect of yttrium on the reaction of tungsten oxide with CO was studied for the preparing various morphologies and size of tungsten carbide. The reaction rate, phase composition, particles size and morphology, surface area of samples were studied by TG (thermogravimetry), XRD (X-ray diffraction), SEM (scanning electron microscopy) and BET (Brunauer–Emmett–Teller), respectively. It was found that the reaction route was following WO 3 → W 18 O 49 → WO 2 → WC at lower temperature, while at higher temperature, an intermediate phase W was formed and then carbonized to WC. During the reaction of pure WO 3 or mixtures (1 wt.% Y(NO 3 ) 3 + WO 3 ) with CO at lower temperature, the final products almost maintained the large irregular block shape. With the increase of temperature, the large WC particles were degraded and the obtained sub-particles became much more dispersed. After the addition of yttrium nitrate, the rod-like sub-particles were transformed into more stable polyhedral-shaped sub-particles with a smaller size. Furthermore, the mechanism of effect of yttrium on prepared tungsten carbides were analyzed in detail.
研究领域:
材料科学
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化学工程
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产品关联
DOI
高影响因子
VACUUM
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2020
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IF 2.906
Qiao Zhang,Yu Cheng,Baojiang Chen,Shuhua Liang,Longchao Zhuo
W–Cu composites that are strengthened with tungsten carbide ceramic particles have been proposed thanks to their high melting point, high hardness and excellent high-temperature mechanical properties . In this paper, tungsten carbide-reinforced W-25 wt% Cu composites were fabricated via an in situ synthesis technique that used mixed tungsten, copper and graphite powders. The impact of the graphite content on the microstructure and properties of the W–Cu composite was investigated. The results showed that tungsten carbide phases formed through the carbonization reaction of tungsten and graphite at high temperature. With the generation of tungsten carbide phases, the hardness, vacuum arc erosion resistance, high-temperature strength and wear resistance of the W–Cu composites were improved. The improvement was very significant for the W–Cu composites with an increase in the graphite content. However, the electrical conductivity was slightly sacrificed for the W–Cu composites. Moreover, the effects of the graphite on the comprehensive properties were evaluated and compared with those of reinforced with CNTs . Based on the laboratory properties and preparation cost of W–Cu composites, graphite can be used for the industrial fabrication of in situ self-generated tungsten carbide-reinforced W–Cu composites.
研究领域:
材料科学
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机械工程
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产品关联
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
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2018
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IF 3.779
Jie Dang,Yijie Wu,Zepeng Lv,Xuewei Lv
Tungsten carbides , which can be widely used as cutting and drilling tools, chemical catalysts and aerospace coatings, have attracted widespread attentions. The present work reported a simple method to prepare tungsten carbides by using WO 2 as the raw materials and CO as the reduction and carbonization agent. It was found that at lower and moderate temperatures, all the final product was WC, while at higher temperatures, the final products were W 2 C or W. The reduction and carbonization mechanism was also studied theoretically and experimentally. WO 2 was reduced and carburized to WC in one step at lower temperatures; WO 2 was first reduced and carburized to W 2 C and then to WC at moderate temperatures; while at higher temperatures, WO 2 was first reduced to metallic W and then carbonized to WC or W 2 C, but with the temperature increasing, the carbonization became difficult and required much higher CO content.
研究领域:
材料科学
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化学工程
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产品关联
DOI
高影响因子
ELECTROCHEMISTRY COMMUNICATIONS
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2021
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IF 4.724
Liwen Zhang,Xiaoli Xi,Zuoren Nie
A new electrochemical method for efficient and green recovery of cemented carbide in a molten salt is described. Tungsten powder is the main product when recovering cemented carbide by molten salt electrolysis. However, the main purpose of tungsten powder is to make tungsten carbide. Based on this, a new method for preparing tungsten carbide by in situ reduction was developed. Pure tungsten carbide powder was successfully prepared in situ by pulse electrolysis in a NaF–KF molten salt system at 1073 K. This not only effectively recovers the spent cemented carbide, but also enriches the product system and optimizes the method for preparation of tungsten carbide powder.
研究领域:
材料科学
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环境工程
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产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
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2024
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IF 5.1
Xu Yonglong,Lei Wang,Nian Wang,Chengfa Mu,Mehrdad Zarinejad,Tao Shen,Hui Yang
Nano tungsten carbide (WC) was synthesized using loose yellow tungsten oxide (WO3) rods, which were derived from violet tungsten oxide (WO2.72) through calcination in dry oxygen. The WO3 rods were then subjected to ball milling with carbon black, followed by carbothermal reduction and carbonization. Unlike conventional methods such as hydrogen reduction or carbothermal reduction, this technique avoids the formation of hydrated tungsten oxides and addresses challenges related to precise carbon control and matching. This streamlined procedure produces nanoscale tungsten carbide particles approximately 150 nm in size, showing great potential for future industrial applications.
研究领域:
材料科学
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化学工程
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产品关联
DOI
高影响因子
INTERNATIONAL JOURNAL OF REFRACTORY METALS & HARD MATERIALS
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2024
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IF 4.2
Hengli Li,Huijun Shang,Feng Pan,Weijun Li,Zhan Du
This article investigated the preparation of ultrafine W powder by fluidized bed hydrogen reduction, and the apparent activation energy was determined for various reduction stages by using temperature programmed reduction with hydrogen. The results demonstrate that the introduction of Co 3 O 4 significantly enhances the reduction process of WO 3 .High Co 3 O 4 content can lead to the formation of CoWO 4 in the initial stage and obtain products with high content of Co 3 W. An increase in the Co 3 O 4 content correlates with a gradual decrease in the particle size of the product. The apparent activation energy for the WO 3 → WO 2 and WO 2 → W processes decreases as the Co 3 O 4 content increases. It can be decreased from 105.59 kJ /mol to 78.72 kJ/mol for the WO 3 → WO 2 stage, and from 107.38 kJ/mol to 78.38 kJ/mol for the WO 2 → W stage, respectively.
研究领域:
材料科学
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化学工程
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）