APPLIED SURFACE SCIENCE
·
2025
·
IF 6.9
Lijun Yang,Jiankun Liu,Yuxi Wang,Huanwen Zhou,Xiaoyuan Liao
In industry, silver-based catalysts are the mainstream choice for converting ethylene to ethylene oxide (EO), and the morphology of Ag particles plays an important role in their catalytic performance; however, related studies are scarce. In this work, evidence from SEM shown that we successfully synthesized three different morphologies of Ag particles induced by different solvent, i.e., flower-like Ag (Fl-Ag), spheroidal Ag (Sp-Ag) and sheet-like Ag (Sh-Ag), dissolve them respectively into the mixed solution of silver nitrate/oxalic acid to form a suspension, then load onto α-Al 2 O 3 . Through were calculated from the XRD peak area the Ag(100) surface occupancy has the order of Fl-Ag (30 %) > Sh-Ag (20 %) > Sp-Ag (15 %), and the selectivity of EO has positive relation with similar order of Fl-Ag/Al 2 O 3 (85 %) > Sh-Ag/ Al 2 O 3 (72 %) > Sp-Ag/Al 2 O 3 (70 %). The selectivity of Fl-Ag/Al 2 O 3 for EO at 210 °C was 85 %. It is shown that Ag(100) surface has better O 2 interaction and activated than that of Ag(111) surface, and (100) has a lower activation energy than the side reaction (0.9 eV vs 1.0 eV), facilitates the conversion of ethylene to ethylene oxide. This study provides a new method to design and optimize silver catalysts.
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高影响因子
CERAMICS INTERNATIONAL
·
2024
·
IF 5.1
Yushi Qi,Jiangfan Xu,Yanhan Fei,Lanjun Du,Yan Ren,Wenbo Han,Gang Chen,Zhiming Du
This study investigated the preparation of SiC porous ceramics using an organic foam impregnation-high temperature sintering process. To address the poor wettability of SiC ceramics when used as the reinforcement phase, the surface of SiC porous ceramics was modified with Al 2 O 3 . SiC-Al 2 O 3 /2A50 co-continuous composites were then fabricated by infiltrating 2A50 aluminum alloy into the SiC-Al 2 O 3 porous ceramics under pressure. Microstructural observations, along with friction, wear performance, and thermal stability test, demonstrated that Al 2 O 3 surface modification significantly enhances the friction and wear performance as well as the thermal stability of the co-continuous composites. The prepared SiC-Al 2 O 3 /2A50 co-continuous composite exhibited excellent wear resistance, good thermal stability and stable bonding at heterogeneous interfaces. Compared to 38CrSi steel, the SiC-Al 2 O 3 /2A50 co-continuous composite not only offers the advantage of reduced weight but also shows a significantly lower wear rate of 9.3 × 10 −5 mm 3 /N·min under a 50 N load. These findings suggest that the SiC-Al 2 O 3 /2A50 co-continuous composite has the potential to replace 38CrSi steel as a wear-resistant material.
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JOURNAL OF WUHAN UNIVERSITY OF TECHNOLOGY-MATERIALS SCIENCE EDITION
·
2021
·Vol. 36
·期 2
·174-182
·
IF 0.957
Shi Minxian,Tang Qingxiu,Fan Shanshan,Dong Chuang,Huang Zhixiong
The ceramifiable polymer composite of MgO-Al 2 O 3 -SiO 2 /boron phenolic resin(MAS/BPF) with 40wt% of inorganic fillers was calcined at 1 200 °C for different time to promote ceramification of ceramifiable composite and improve heat resistance. The effects of different calcine time on the macroscopical morphology, mass loss, phase evolution, microstructure and chemical bond evolution of MAS/BPF composites were characterized by XRD, XPS, and SEM analyses. The experimental results reveal that the increase of calcine time result in the fewer holes, relatively denser and smoother top layer of MAS/BPF composites and protect the interior from deeper decomposition. The final residues of composites are amorphous carbon and C-O-Si-Al-Mg ceramic. And MAS/BPF composites show excellent mass stability, low shrinkage and self-supporting features after 2 h holding compared with BPF composites without 40wt% of inorganic fillers.
研究领域:
材料科学
·
无机化学
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高影响因子
JOURNAL OF CHEMICAL TECHNOLOGY AND BIOTECHNOLOGY
·
2024
·
IF 2.8
Boyun Gao,Huijiang Huang,Mooeez Ur Rehman,Bin Ren,Yuruo Liu,Weipeng Fan,Pengfei Li,Lizhi Zhang,Yan Xu,Yujun Zhao
BACKGROUND The synthesis of fatty amines via fatty alcohol amination offers a promising avenue for environmentally friendly production, particularly when compared with the methods employing hydrocyanic acid which often involve significant emissions. RESULT This study explores the synthesis of n-hexylamine through one-step amination of n-hexanol utilizing a series of Ru-doped Ni catalysts supported over γ-Al 2 O 3 , achieving 61% n-hexanol yield, 35% dihylamine yield and 3.5% trihylamine yield at the n-hexanol conversion of 99%. CONCLUSION The characterization results of the catalysts revealed a significant interaction between ruthenium and nickel in the bimetallic catalysts, leading to the enhanced reducibility of Ni species and improved metal dispersion. Moreover, ruthenium species were found to play an important role in the dissociation of NH 3 into NH x (x = 1, 2), thereby significantly improving the dehydrogenation process of n-hexanol at Ni sites. The synergistic effect between the two kinds of metal sites emerges as crucial factor for the boosted alcohols amination process. © 2024 Society of Chemical Industry (SCI).
研究领域:
催化化学
·
环境科学
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高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2020
·
IF 4.65
Xiaolei Song,Kechao Zhang,Ying Song,Zhenxin Duan,Qiang Liu,Yang Liu
Alumina nanofibers with excellent mechanical properties are an ideal candidate as the reinforcements for composites. In this study, alumina nanofibers were fabricated via electrospinning technique combined with the sol–gel method. Alumina precursor sol was prepared using aluminum nitrate and aluminum isopropoxide. The morphology, microstructure, and mechanical properties of the nanofibers prepared using polyvinyl alcohol, polyvinyl butyral, and polyvinyl pyrrolidone as the polymer templates after calcination at 900 °C were investigated and compared. The three fiber samples exhibited continuous structure and the same phase composition of γ -Al 2 O 3 . However, the surface roughness , diameter distributions, densification degrees, crystallization temperatures, grain sizes, tensile strength , and elastic modulus were completely different. Possible mechanisms for these differences were discussed on the basic of the homogeneity of spinning solutions, the decomposition behaviors of polymers, and the quantities and sizes of defects and grains. The findings of this study can help in understanding an often-neglected concept on the important role of polymer categories on the structure and properties of electrospun oxide nanofibers, particularly required with enhanced mechanical properties.
研究领域:
材料科学
·
纳米技术
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高影响因子
MATERIALS LETTERS
·
2021
·
IF 3.423
Hong Guo,Fei Shen,Weichang Guo,Dingyuan Zeng,Yuting Yin,Xiaogang Han
All-solid-state batteries with garnet-type solid electrolytes are expected to achieve high safety. However, poor contact between the cathode and the solid-state electrolyte remains a bottleneck in improving electrochemical performance. We propose an interface modification strategy by adopting nano γ-Al 2 O 3 as a co-sintering additive to address the interfacial issue. The Li|Li 6.75 La 3 Zr 1.75 Nb 0.25 O 12 |LiCoO 2 all-solid-state battery exhibits promoted capacities due to intimate interfacial contact between the cathode and the electrolyte after modification. This work provides a low-cost and convenient strategy to overcome the interfacial issue in all-solid-state batteries.
研究领域:
材料科学
·
能源技术
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DOI
高影响因子
INTERNATIONAL JOURNAL OF REFRACTORY METALS & HARD MATERIALS
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2021
·
IF 3.871
Kai-Fei Wang,Xiao-Hui Yang,Kuo-Chih Chou,Guo-Hua Zhang
Oxide dispersion strengthened (ODS) WC Co cemented carbides with excellent mechanical properties were prepared by a facile three-step method. First, the mixture of ammonium paratungstate, cobalt oxalate and aluminum nitrate nonahydrate were roasted to generate precursor powder. Then, the precursor powder was reacted with insufficient carbon black to remove oxygen to aid precise carbon addition in the next step. Finally, depending on the carbon content difference between carbothermic reduction products and target product, the sample was mixed with the required carbon black to prepare WC Co Al 2 O 3 cemented carbides directly by the method of powder sintering . Experiments showed that after the addition of uniformly distributed nano-sized Al 2 O 3 particles, the mechanical properties included hardness and toughness of ODS cemented carbides improved. When the content of Al 2 O 3 was 0.5%, the densification of finally prepared WC-5.5wt%Co-0.5wt%Al 2 O 3 alloy could reach to 99.08%, and the values of fracture toughness and Vickers hardness were 11.35 ± 0.60 MPa·m 1/2 and 1756 ± 20.92 HV, respectively, thus giving excellent results.
研究领域:
材料科学
·
金属学
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高影响因子
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
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2025
·
IF 3
Qi Li,Zhangqiao Zhou,Yan Nie,Lu Yang,Yu Wang,Jinsong Chen,Xian Wang
The preparation of soft magnetic composites requires effective surface modification of alloy powder to enhance insulating properties and achieve dense, uniform coating layers. Firstly, the gas-atomized Fe-Ni-Mo powder was surface modified using the atomic layer deposition method, forming a uniform and dense Al 2 O 3 insulating layer. The secondary surface modification of organic polymers further improves the properties of soft magnetic composites. This study systematically evaluates the effects of the primary and secondary surface modification on the properties of powder particles and soft magnetic composites. The primary modification generates an extremely thin insulating layer of approximately 2.5 nm, which increases the particle resistivity by 9 orders of magnitude. The permeability frequency stability of the soft magnetic composites increased from 11.3 % to 96.5 %, resulting in significant core loss reduction. The secondary modification effectively enhances the formability of soft magnetic composites. Optimal permeability of 242.7 at 1 kHz is achieved, maintaining 95.2 % frequency stability up to 1 MHz, while core loss remains below 570 mW cm −3 under 100 kHz/100 mT conditions. The surface treatment method in this work can provide a reference for the surface insulation modification of soft magnetic composites.
研究领域:
材料科学
·
电磁学
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Journal of Advanced Ceramics
·
2018
·Vol. 7
·期 2
·152-159
·
IF 1.605
Wu Jia-Min,Xiao Huan,Liu Meng-Yue,Chen Ying,Ma Yi-Xin,Cheng Li-Jin,Shi Yu-Sheng
In this paper, in-situ coagulation of 0.9Al 2 O 3 –0.1TiO 2 suspension and microwave dielectric properties of 0.9Al 2 O 3 –0.1TiO 2 ceramics prepared by a novel direct coagulation casting via high valence counter ions (DCC-HVCI) method were proposed. The 0.9Al 2 O 3 –0.1TiO 2 suspension could be coagulated via controlled release of calcium ions from calcium iodate at an elevated temperature. The influence of tri-ammonium citrate (TAC) content, solid loading, and calcium iodate content on the rheological properties of the suspension was investigated. In addition, the influence of coagulation temperature on coagulation time and properties of green bodies was also studied. It was found that the stable 0.9Al 2 O 3 –0.1TiO 2 suspension could be successfully prepared by adding 0.3 wt% TAC and adjusting pH value to 10–12 at room temperature. 0.9Al 2 O 3 –0.1TiO 2 green bodies with uniform microstructures were coagulated by adding 8.0 g/L calcium iodate after treating at 70 °C for 1 h. 0.9Al 2 O 3 –0.1TiO 2 ceramics, sintered at 1500 for 4 h and annealed at 1100°C for 5 h, showed °Cuniform microstructures with density of 3.62±0.02 g/cm 3 . The microwave dielectric properties of 0.9Al 2 O 3 –0.1TiO 2 ceramics prepared by DCC-HVCI method were: ε r = 11.26±0.06, Q × f = 11569±629 GHz, τ
f
= 0.93±0.60 ppm/°C. The DCC-HVCI method is a novel and promising route without binder removal process to prepare complex-shaped microwave dielectric ceramics with uniform microstructures and good microwave dielectric properties.
研究领域:
材料科学
·
陶瓷学
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高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2023
·
IF 6.2
Junjie Lu,Xueqin Zhang,Suwen Li,Lu Zhang,Wenqing Wang,Zengchan Li,Yanpeng Zhang,Gang Wang,Ying Li,Rujie He
In this study, Al 2 O 3 triply periodic minimal surface (TPMS) scaffolds with cell sizes of 5 mm, 8.5 mm, and 12 mm were prepared by vat photopolymerization 3D printing , and Al 2 O 3 /Al ceramic-metal hybrid structures were subsequently obtained by the metal infiltration of AlSi10Mg. To investigate the influence of cell size on the mechanical properties of vat photopolymerization 3D printed Al 2 O 3 TPMS scaffolds and Al 2 O 3 /Al hybrid structures, quasi-static compression and dynamic impact experiments were conducted, and the failure modes during experiments were discussed. It was shown that the quasi-static compression and dynamic impact properties of Al 2 O 3 TPMS scaffolds gradually decreased with the increase in cell size, the compression strength decreased from 15.2 MPa to 8 MPa and the impact strength decreased from 37 MPa to 11 MPa, respectively, which was related to the stress transfer ability of the single cell. In contrast, the effects of cell size on the performance of Al 2 O 3 /Al hybrid structures were opposite. When the cell size increased, the quasi-static compression performances of the Al 2 O 3 /Al hybrid structure were greatly improved, and the compression strength increased from 175 MPa to 250 MPa. The impact resistances of the Al 2 O 3 /Al hybrid structure were further studied. The highest impact strength of the Al 2 O 3 /Al hybrid structure was 290.74 MPa. With the increase in cell size, the impact resistance of the Al 2 O 3 /Al hybrid structure had a gradual improvement trend. Under the cyclic impact, the Al 2 O 3 /Al hybrid structure showed a high impact strength and energy absorption capacity, which was mainly related to the metal phase content around the cell, i.e., the coherence of the metal phase. This study is believed to give help for the structural design of ceramic scaffolds and ceramic-metal hybrid structures.
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APPLIED CATALYSIS B-ENVIRONMENTAL
·
2018
·
IF 11.698
Suqian Xu,Hanxu Zhu,Wenrui Cao,Zhibin Wen,Jinnan Wang,Corvini Philippe François-Xavier,Thomas Wintgens
Cu-Al 2 O 3 -g-C 3 N 4 and Cu-Al 2 O 3 -C-dots were synthesized for the first time to enhance the catalytic activity and utilization of H 2 O 2 . SEM, TEM, XPS, FT-IR, XRD, TPR and solid-state EPR were used to characterize the catalysts. In the Cu-Al 2 O 3 -g-C 3 N 4 system, the electron-rich centre of Cu and electron-deficient site of Al were formed due to the higher electronegativity of Cu. Moreover, Cu ions could coordinate with the hydroxyl on the tri-s-triazine ring of g-C 3 N 4 or the graphene conjugated π-domains of C-dots via the Cu O C linkage so that the orbital interactions involving electron transport from π → Cu also induced the formation of an electron-rich Cu centre and an electron-deficient π-electron conjugated system, resulting in the strengthening of the dual-reaction centres. This mechanism was validated by Roman, EPR and XPS spectra. In addition, EPR experiments demonstrated that two electron-transfer processes formed OH in the presence of H 2 O 2 . The first electron transfer was from the electron-rich Cu centres to H 2 O 2 , and the other was from H 2 O to the electron-deficient site. Thus, more OH were generated and high H 2 O 2 utilization was achieved in the Cu-Al 2 O 3 -g-C 3 N 4 and Cu-Al 2 O 3 -C-dots suspension. Furthermore, the turnover frequency (TOF) for the Cu-Al 2 O 3 -C-dots and Cu-Al 2 O 3 -g-C 3 N 4 dispersions were determined and were found to be much higher than those of the classic homogeneous Fenton reaction. Thus, Cu-Al 2 O 3 -g-C 3 N 4 and Cu-Al 2 O 3 -C-dots showed high activity and stability for the catalytic degradation of organic pollutants under mild conditions.
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CHINESE JOURNAL OF CATALYSIS
·
2018
·
IF 3.525
Dawei He,Danhua Yuan,Zhijia Song,Yunpeng Xu,Zhongmin Liu
Zeolite synthesis in contemporary chemical industries is predominantly conducted using organic structure-directing agents (OSDAs), which are chronically hazardous to humans and the environment. It is a growing trend to develop an eco-friendly and nuisanceless OSDA for zeolite synthesis. Herein, choline is employed as a non-toxic and green OSDA to synthesize high silica Y zeolite with SiO 2 /Al 2 O 3 ratios of 6.5–6.8. The prepared Y zeolite samples exhibited outstanding (hydro)thermal stability at ultrahigh temperature owing to the higher SiO 2 /Al 2 O 3 ratio. The XRF, SEM, 29 Si-NMR and 13 Na+ results suggested that choline plays a structure-directing role in the synthesis of Y zeolite, while the feed molar fraction of Na + is a crucial determinant for the framework SiO 2 /Al 2 O 3 ratio and the crystal morphology.
研究领域:
材料科学
·
环境科学
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DOI
高影响因子
危险品化学品经营许可证（带存储）