INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2023
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IF 7.2
Shanshan Duan,Xun Wang,Ruipeng Ren,Yongkang Lv
One of the most effective methods of utilizing CH 4 and CO 2 resources is the dry reforming of methane (DRM). However, the small particle size and the metal-support interactions of Ni–W bimetallic catalysts are key factors affecting activity and carbon deposition . This article evaluates the effect of Ni–W bimetallic catalysts synthesized by different preparation methods on their catalytic performance in DRM reactions. The results show that the bimetallic catalyst prepared by the solid-state grinding method exhibits excellent catalytic performance and anti-carbon deposition performance. The conversion rate of CH 4 and CO 2 remain unchanged during 1450 min, which is 58% and 66%, respectively. Through various characterization methods, it has been proven that the bimetallic catalyst prepared by the solid-state grinding method effectively reduces the size of Ni particles and increases the number of exposed active sites. In addition, this method also enhances the metal-support interactions, which helps to improve the stability of the catalyst.
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VACUUM
·
2020
·
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.
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CHEMICAL ENGINEERING JOURNAL
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2020
·
IF 10.652
Liyu Zheng,Sanyuan Hu,Heping Li,Youwei Yan
The fast development of optoelectronics makes a huge boost to the searching for flexible indium-free transparent conductors. In recent years, metal networks (currently are Au, Ag and Cu) have emerged as promising alternatives, however, facile fabrication of high-performance, chemically stable, and low-cost transparent conductor is still a big challenge. Here, ultra-long W microfibers (with conductivity of 4.3 × 10 4 S/cm) are successfully produced by draw spinning and further assembled into well-regulated patterns. Such a solution-processed patterning effectively eliminates the fiber-to-fiber joint resistance, and thus enables the W network to achieve an ultra-low sheet resistance of 0.2 Ω sq −1 at ~90% transparency, which corresponds to a high figure of merit σ dc /σ opt = 1.7 × 10 4 (up to 10–40 times the value of Cu and Au networks). Moreover, the W network possesses excellent anti-thermal and anti-corrosion properties, which enable it to work in the erosion solution with pH ranging from 1 to 13 with a restrained increase (<3%) in its sheet resistance. With a marvelous combination of high conductivity and transparency, high chemical stability and good mechanical flexibility, the ultrathin W fibers may open a new door to find flexible indium-free transparent conductors for the development of both flexible electronics and energy conversion.
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FUEL
·
2021
·
IF 6.609
Hanzi Liu,Yi Zhang,Haiming Wang,Changfu You
Selective non-catalytic reduction of NOx (SNCR) with NH 3 is commonly used in industrial facilities like circulating fluidized bed (CFB) furnaces. However, the strongly temperature-dependent de-NOx feature confines its applications in a specific temperature range (900–1050 °C). Here, we report a new strategy on using Fe-Ni-W exchanged zeolite (0.5FNW-H) as a catalyst to extend the SNCR temperature window. In the CFB reactor, a significant NOx conversion improvement ranging from 14.1% to 80.9% was achieved at 700 to 850 °C by applying the developed catalyst. Catalyst dosage of 4500 h −1 (GHSV), a particle diameter of 0.1–0.3 mm, and NH 3 injection position at the dense-phase zone were found preferred for NOx reduction with the highest efficiency of ~85% at 700 °C. The physicochemical properties of the catalysts remained stable after the circulating reactions in the CFB reactor. The developed catalyst is particularly applicable for improving the SNCR performance when the thermal power plants are operated at low loads.
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INORGANIC CHEMISTRY
·
2019
·
IF 4.85
Jie Xu,Mingshuo Wang,Fei Yang,Xiaoqian Ju,Xilai Jia
Structural and compositional modulation of low-cost hydroxide is important for making efficient electrocatalysts of the oxygen evolution reaction (OER), and it is an ongoing challenge. Here, Ni–Fe–W hydroxide complex by incorporation of tungsten into nickel–iron layered double hydroxide was proposed and investigated. As-formed Ni–Fe–W hydroxide nanosheets are highly porous and self-supported on the carbon fiber substrates, which promote the exposure of the active metal sites for significantly enhanced OER activity. Moreover, the as-introduced tungsten is evidenced to be in a W6+ oxidation state which can facilitate charge transfer and electron capture and thereby decrease the critical conversion barrier of the absorbed OH– to O radical in OER. A series of Ni–Fe–W hydroxides were prepared, with the best molar ratio of Ni–Fe–W sources being 6:2:1. The optimal Ni6Fe2W-LDH@carbon fiber electrode delivers a low overpotential of 264 mV at 10 mA cm–2 and high stability (only 1.6% of the potential increase after 10 h) in alkaline electrolyte. Moreover, the structure of the constructed Ni–Fe–W hydroxide is evidenced to be stable and important for the electrocatalytically stable. The study is expected to open a new avenue in developing multiple hydroxides for low-cost and efficient electrocatalysts.
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PubMed
高影响因子
ENERGY & FUELS
·
2019
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IF 3.021
Zhiming Huang,Ping Li,Xiao Luo,Xia Jiang,Lei Liu,Fan Ye,Jiazhe Kuang,Yue Luo,Yuanzhu Mi
In the current study, novel environmentally friendly and interfacially active carbon nanotubes/SiO2 nanomaterials (CNTs/SiO2) for emulsified crude oil separation were prepared via grafting nano-SiO2 on the surface of oxidized carbon nanotubes (Ox-CNTs). The structure of the as-prepared CNTs/SiO2 was characterized by Fourier transform infrared spectroscopy, UV–visible absorption spectra, Raman spectra, X-ray diffraction spectra, thermogravimetric analysis, field-emission scanning electron microscope, and energy-dispersive X-ray spectroscopy. Besides, three-phase contact angles (θ) were employed to evaluate the wettability of CNTs/SiO2. Also, it was found that the θ value of CNTs/SiO2 was about 90°. The nanomaterials with interfacial activity can spontaneously assemble at the oil–water interface, thus improving the droplet coalescence in the emulsion. Afterward, the demulsification performance was evaluated in crude-oil emulsions using the bottle test, which demonstrated that the demulsification efficiency demulsification efficiency could reach 87.40%. Also, the water phase was clear, while the optimum concentration and sedimentation time were 500 ppm and 30 min, respectively. Furthermore, the possible demulsification mechanism was evaluated by an optical microscope. The findings in this work might provide a novel environmentally friendly and interfacially active nanomaterial as a crude oil demulsifier.
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JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
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2019
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IF 3.571
Shanshan Wang,Jiawen Fan,Lujing Xu,Kai Ye,Tong Shu,Songbai Liu
In this study, derivatization of epigallocatechin (EGC) by representative phytosterols (stigmasterol and β-sitosterol) was performed employing Steglich esterification. The structural identity and purity of epigallocatechin β-sitosterol (ESi) and epigallocatechin stigmasterol (ESt) were confirmed by NMR, FT-IR, and HPLC-MS. Further evaluation of ESi and ESt revealed their extraordinary antioxidant activities in O/W emulsion. Two different radical sources in oil or aqueous phase were applied to explore the antioxidant behavior in O/W emulsion. The mechanism was further investigated by fluorescent microscopy and transmission electron microscopy (TEM). Furthermore, incorporation of EGC with stigmasterol and β-sitosterol notably enhanced the cholesterol-reducing activity. TEM studies suggested the hydrogen bonding of EGC strengthened the aggregation network of ESi and ESt in the bile salt micelle. The exceptional properties of ESi and ESt signified their intriguing utilization in the food industry.
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PubMed
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INTERNATIONAL JOURNAL OF REFRACTORY METALS & HARD MATERIALS
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2018
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IF 2.606
Kejia Kang,Rong Tu,Guoqiang Luo,Jian Zhang,Jiawen Zhu,Qiang Shen,Lianmeng Zhang
In this research, the high-temperature mechanical, electrical and thermal properties of arc-melted W-based composites with a small amount of SiC additives were investigated. The high-temperature mechanical properties of tungsten were enhanced by the presence of the hard ceramic phase (W 5 Si 3 and W 2 C) and the interaction of dislocations. The ceramic phase also played a role in inhibiting the grain growth at high temperatures. The ultimate compressive strength (UCS) of the W with 1 wt% SiC (S1) was 968.9 MPa at 1273 K, which is three times that of pure W (291.9 MPa) at 1273 K, showing a significant enhancement in high-temperature strength . Both thermal conductivity ( κ ) and electrical conductivity ( σ ) decreased with the increasing of SiC addition. With increasing temperature, the σ decreased while the κ increased due to the intrinsic behavior of the ceramic phase in the composites.
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DRUG DEVELOPMENT AND INDUSTRIAL PHARMACY
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2018
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IF 1.883
Yi Chen,Qianming Du,Qianqian Guo,Jing Huang,Lina Liu,Xiangchun Shen,Jianqing Peng
The CaCO3 encapsulated liposome with pH sensitivity is an efficient carrier for the delivery of chemotherapeutic drugs. Herein, we provided an innovative method that take advantage of a W/O emulsion to prepare CaCO3 encapsulated liposomes for the delivery of curcumin. The liposomes with both CaCO3 and curcumin encapsulated (LCC) showed high sensitivity to reduced pH (the environment of lysosomes). Due to the inherent pH sensitivity of CaCO3, LCC swelled and released the encapsulated curcumin rapidly in acidic medium. The lysosome escape capability and promoted accumulation of curcumin in the cytosol from LCC was verified with respect to that of curcumin loaded liposomes (CLIPO). Despite the similar cytotoxicity within curcumin preparations in vitro at high concentration, LCC exhibited optimal antitumor effect in an azoxymethane (AOM)/dextran sodium sulfate (DSS)-induced colorectal cancer model, which was attributed to the long circulation time and efficient intracellular delivery of curcumin from LCC. It is suggested that the solubility and cytosolic delivery of curcumin are greatly improved by LCC, which accounts for the increased pharmacodynamic effect of curcumin. Thus, the CaCO3 encapsulated liposomes developed in this study is an ideal carrier for the hydrophobic drugs in potential clinical application.
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RSC Advances
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2015
·Vol. 5
·期 30
·23981-23989
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IF 3.84
Wei Xu,Chao Lin,Huan Liu,Hongbo Yu,Kai Tao,Shenghu Zhou
Tungsten substituted mesoporous FDU-12 (W-FDU-12) catalysts were synthesized by a one-pot hydrothermal process using F127 as the structure directing agent. The studies of TEM, SAXS and BET illustrated that the highly ordered mesoporous structure of FDU-12 was maintained in the doped W-FDU-12 samples. XPS studies revealed that a high concentration of W5+ species appeared in doped W-FDU-12 catalysts whereas supported WO3/FDU-12 and WO3/SiO2 catalysts only contained W6+ species. Tandem catalytic conversion of 1-butene and ethene to propene through isomerization of 1-butene to 2-butene and consecutive cross metathesis of 2-butene and ethene in a fixed-bed reactor at different temperatures and atmospheric pressure was used to evaluate the catalytic performance of the W-FDU-12 catalyst, combined with MgO. The catalytic results showed that the doped W-FDU-12 illustrated a superior catalytic performance relative to the supported WO3/FDU-12 and WO3/SiO2 catalysts. The higher metathesis activity of W-FDU-12 catalysts can be ascribed to the good dispersion of W species and the incorporation of W species into the framework of FDU-12, forming a substantial amount of W5+, which was beneficial for the cross metathesis of 2-butene and ethene to propene.
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CHINESE JOURNAL OF CHEMICAL ENGINEERING
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2016
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IF 1.207
Zhiliang Zhang,Guangquan Wang,Yong Nie,Jianbing Ji
Hydrodynamic cavitation, a newly developed process intensification technique, has demonstrated immense potential for intensifying diverse physical and chemical processes. In this study, hydrodynamic cavitation was explored as an efficient method for the formation of sub-100 nm oil-in-water (O/W) emulsions with high stability. O/W emulsion with an average droplet size of 27 nm was successfully prepared. The average droplet size of O/W emulsions decreased with the increase of the inlet pressure, number of cavitation passes and surfactant concentration. The formed emulsion exhibited admirable physical stability during 8 months. Moreover, the hydrodynamic cavitation method can be generalized to fabricate large varieties of O/W emulsions, which showed great potential for large-scale formation of O/W emulsions with lower energy consumption.
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COMPOSITES PART B-ENGINEERING
·
2024
·
IF 12.7
Junjie Xu,Wei Sun,Xiang Xiong,Hongbo Zhang
Compared with the traditional C/C composites modified by ultra-high-temperature ceramics (C/C-UHTCs), those modified by metal/medium-entropy ceramics have excellent mechanical properties, thermophysical properties, and long-term ablation resistance. These composites have great potential towards improving the high-temperature resistance and service life of thermal protection systems for spacecraft. In this study, a new type of (Hf 0.5 Zr 0.3 Ti 0.2 )C–W–Cu cermet-modified C/C composites (C/C-(Hf 0.5 Zr 0.3 Ti 0.2 )C–W–Cu) was prepared at 1500 °C. Compared with C/C-UHTCs, the bending strength and fracture toughness of C/C-(Hf 0.5 Zr 0.3 Ti 0.2 )C–W–Cu increased by 70 % and 110 % to 364.25 MPa and 14.64 MPa m 1/2 , respectively. Due to the high thermal conductivity of Cu and W, the thermal conductivity of this new composite was 106 % higher than that of C/C-(Hf 0.5 Zr 0.3 Ti 0.2 )C (44.26 versus 21.53 W/m·K). Under a high heat flow of 4.18 MW/m 2 , this material exhibited very low mass and linear ablation rates (−0.163 mg/s and −0.193 μm/s, respectively). Active and passive protection occur during ablation due to the evaporative cooling of Cu, CuO, and WO 3 as well as a dense outer oxide layer that inhibits oxygen diffusion. The internal oxide layer forms a Hf-Zr-Ti-C-O framework mingled with Ti-rich Ti-Hf-Zr-C-O and an unoxidised W–Cu structure, effectively reducing the osmotic oxygen content. This work provides a new direction for developing thermal protection materials capable of long-term service in ultra-high-temperature environments.
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