MATERIALS CHEMISTRY AND PHYSICS
·
2015
·
IF 2.259
Yicheng Wu,Zhiqiang Yu,Yannan He,Xiaolei Yang
The heat conduction of TiB 2 –Al 2 O 3 /epoxy composites was discussed by comparisons of the finite element model (FEM), the self-consistent model, and experimental results. The experimental thermal conductive performance of epoxy composites was characterized by laser flash method. According to the calculated and experimental results, TiB 2 showed optimistic potential in improving thermal conductive performance of epoxy composites. With the addition of Al 2 O 3 particles, the thermal conductive performance of epoxy composites filled by TiB 2 –Al 2 O 3 composite fillers was improved remarkably at high volume fraction. After surface modification of ceramic fillers by silane coupling agents, the efficiency of the heat diffusion of epoxy composites was increased further. In comparison of the finite element analysis (FEA), the self-consistent model and experimental results, the thermal conductive values of FEA were in reasonable agreement with experimental values, and the calculated values from self-consistent models were lower than the experimental values slightly.
研究领域:
材料科学
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工程热物理
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
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2021
·Vol. 32
·期 23
·27871-27881
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IF 2.478
Zhang Hongda,Zhou Hong,Liu Guolong,Ge Jing,Jin Liguo
The hybrid fillers (Al 2 O 3 –ATP hybrids) composed of two types of inorganic materials—modified alumina (Al 2 O 3 ) and modified attapulgite (ATP)—were principally prepared, following which the epoxy matrix (EP) composites reinforced with Al 2 O 3 –ATP hybrids were synthesized. The mechanical and dynamic mechanical properties of fabricated Al 2 O 3 –ATP/EP composites are enhanced by doping Al 2 O 3 –ATP hybrids into EP. The highest impact and flexural strength of EP composites (3 wt% Al 2 O 3 –3 wt% ATP/EP) are improved to 27.88 kJ/m 2 and 157.04 MPa, which are 457.6% and 89.2% higher than those of the pure epoxy resin, respectively. The glass transition temperature of Al 2 O 3 –ATP/EP composites increases by 8.8 °C, compared with pure EP composites and the dielectric constant and dielectric loss can reach 3.19 and 0.0041 at 100 Hz. These excellent mechanical and dynamic mechanical properties, accompanied by dielectric property may expand the practical applications of EP composites in industrial engineering.
研究领域:
材料科学
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工程学
✓ 已验证
产品关联
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2020
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IF 3.573
Meng Chen,Wei Lu,Hejun Zhu,Leifeng Gong,Ziang Zhao,Yunjie Ding
Linear α-olefins (C8–C12 α-olefin, LAOs) are acknowledged as high-value-added chemicals in both lubricant production and the polyolefin industry. An alternative route to the synthesis of high-purity LAOs is the dehydration of linear long-chain n-alcohols, whereas elevating the activity and selectivity of catalysts remains a challenge. Herein, we presented that on using sodium-modified γ-Al2O3 as the catalyst, a high selectivity (up to 96.87%) to 1-decene was achieved, and an optimized experimental condition (329 °C and 0.25 h–1) was found using the response surface method. Characterization results including X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), pyrolysis (Py)-IR, NH3-temperature-programmed desorption (TPD), and CO2-TPD showed that a suitable ratio (∼0.4 wt %) of sodium impregnation could inhibit the strong acid sites of the catalyst, and sodium impregnation led to the formation of additional base sites, which accounted for the synergistic effect with other acid sites to promote further conversion of ethers to olefins. This work is of significance for the synthesis of LAOs from long-chain n-alcohols.
研究领域:
催化化学
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材料科学
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石油化工
✓ 已验证
产品关联
DOI
高影响因子
RSC Advances
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2016
·Vol. 6
·期 56
·51221-51228
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IF 3.289
Yanliang Yang,Jiping Ma,Xiuquan Jia,Zhongtian Du,Ying Duan,Jie Xu
Al2O3 modified by alkaline earth metals M–Al2O3 (M = Mg, Ca, Sr, Ba) was synthesised by coprecipitation method. The nickel-based catalysts supported by M–Al2O3 were prepared by impregnation method. The catalysts were characterized by TEM, N2 adsorption/desorption, XRD, H2-TPR, NH3-TPD and XPS, and used for the direct hydrogenation of furfural to tetrahydrofurfuryl alcohol (THFA) in water. The reaction was demonstrated to proceed through furfuryl alcohol as an intermediate. The modification of Al2O3 by alkaline earth metals has a significant effect on the activity and selectivity of THFA. A high yield of THFA was obtained over Ni/Ba–Al2O3 under optimized conditions. Moreover, the catalyst is recyclable and reusable at least four times without significant loss of the conversion of furfural and selectivity of THFA.
研究领域:
催化化学
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绿色化学
✓ 已验证
产品关联
DOI
高影响因子
ENERGY & FUELS
·
2021
·
IF 3.605
Beibei Feng,Yitong Zhai,Lidong Zhang
The combustion and catalytic combustion of ethanol (a typical bioalcohol) at atmospheric pressure and an equivalence ratio of ϕ = 3 were investigated in a flow reactor. Reactants, important intermediates, and products were detected and identified by gas chromatography–mass spectrometry. For ethanol combustion, the hydrogen abstraction reaction attacked by OH radicals is the initial pathway for ethanol consumption. Acetaldehyde is regarded as an important intermediate in ethanol combustion through kinetic analysis. However, catalytic combustion of ethanol over γ-Al2O3 is dominated by bimolecular and unimolecular dehydration reactions to produce diethyl ether and C2H4, while Pd/γ-Al2O3 can strongly oxidize ethanol to CO2 with a dramatic decrease in the decomposition temperature. To further understand the mechanism of catalytic combustion, pyrolysis and catalytic pyrolysis of ethanol were also explored. The product distribution in catalytic pyrolysis demonstrated weaker coke deposition over γ-Al2O3 in comparison to catalytic combustion. In addition, the deactivation of Pd/γ-Al2O3 at high temperatures was probably due to the increase in the concentration of oxygenated species to cover the active Pd site. The apparent activation energy was estimated by the Arrhenius equation to illustrate the difference in primary reaction channels. This work bridges the gap between combustion and catalytic combustion of ethanol, which is beneficial for the improvement of catalytic performance and control of pollutants by combining pyrolysis and combustion.
研究领域:
化学工程
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环境科学
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能源科学
✓ 已验证
产品关联
DOI
高影响因子
ELECTROCHIMICA ACTA
·
2015
·
IF 4.504
Bo Liang,Siqi Tang,Qingbai Jiang,Chuangsheng Chen,Xu Chen,Shengliang Li,Xuehui Yan
This paper presents the preparation and characterization of a series of PEO-PMMA composites containing different lithium salts (LiClO 4 or LiTFSI) with or without nano-Al 2 O 3 . Nano-Al 2 O 3 is added to the polymer electrolytes to alter the morphology, ionic conductivity , interfacial and thermal shrinkage properties. Nano-Al 2 O 3 can effectively improve the stability of the polymer electrolyte membrane interface. The tensile strength of the PEO-PMMA-LiTFSI-Al 2 O 3 electrolyte membrane is 3.24 MPa at room temperature . The study shows that the ion conductivities at room temperature for PEO-PMMA-LiTFSI (EO/Li + = 10) and PEO-PMMA-LiTFSI-Al 2 O 3 (EO/Li + = 10) are 6.71 × 10 −7 S/cm and 9.39 × 10 −7 S/cm, respectively. A good dimensional stability was observed for PEO-PMMA-LiTFSI with a thermal shrinkage of 8.7%. The electrochemical windows of PEO-PMMA-LiTFSI and PEO-PMMA-LiTFSI-Al 2 O 3 are all stable up to 4.6 V versus Li + /Li, which makes them good electrolyte candidates of lithium ion batteries with high-potential cathodes.
研究领域:
材料科学
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电化学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Energy Chemistry
·
2017
·
IF 2.594
Jinwei Sun,Yujiang Wang,Haikui Zou,Xiaoguang Guo,Zhou-jun Wang
Nanosheet (S) and nanoplate (P) γ-Al 2 O 3 were synthesized by simple hydrothermal methods and employed as supports for Ni catalysts in CO 2 methanation . Both of the nanostructured Ni/Al 2 O 3 catalysts displayed good activity. In comparison, the Ni/Al 2 O 3 -S catalyst showed higher CO 2 conversion than the Ni/Al 2 O 3 -P counterpart at the reaction temperature ranging from 250 to 400 °C. The physical and chemical properties of the catalysts were systematically characterized by N 2 sorption , X-ray diffraction (XRD), high resolution-transmission electron microscopy (HR-TEM), hydrogen temperature-programmed reduction (H 2 -TPR) and CO 2 temperature-programmed desorption (CO 2 -TPD) techniques. Higher specific surface area and stronger metal-support interactions were confirmed on the Ni/Al 2 O 3 -S catalyst, which may lead to smaller particle size of Ni nanoparticles . Moreover, the Ni/Al 2 O 3 -S catalyst possessed more abundant weak and medium basic sites, which would benefit the activation of CO 2 . The smaller Ni size and more suitable basic sites may rationalize the superior activity of the Ni/Al 2 O 3 -S catalyst. Besides, the Ni/Al 2 O 3 -S catalyst exhibited excellent stability at 325 °C for 40 h.
研究领域:
化学工程
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催化材料
✓ 已验证
产品关联
DOI
高影响因子
DALTON TRANSACTIONS
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2022
·Vol. 51
·期 48
·18562-18571
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IF 4.569
Han Zhao,Longchun Bian,Junchen Du,Yunkun Zhao
The Pd distribution and the CeO2–Al2O3 combination are among the decisive factors for the performance of commercial three-way catalysts. Generally, the sufficient doping of Pd into ceria-based oxides and the intimate interaction between CeO2 and Al2O3 could both benefit the three-way catalytic reactions. However, in the present work, the moderate doping of Pd into CeO2 and less intimate CeO2–Al2O3 interaction were found to be responsible for the much higher catalytic activity (the decrease in T50 was 52, 119, or 55 °C for C3H6, CO, or NO) in PdCe/Al2O3-CP than PdCe/Al2O3-Imp, for which the Pd and Ce species were co-loaded onto Al2O3 through the co-precipitation or impregnation method, respectively. It was intriguing to find that the co-precipitated PdCeOx in PdCe/Al2O3-CP showed less sufficient doping of Pd into CeO2 than the co-impregnated PdCeOx in PdCe/Al2O3-Imp; as a result, both a higher fraction of highly active metallic Pd and a higher Pd dispersion were realized in PdCe/Al2O3-CP. Moreover, due to the less intimate CeO2–Al2O3 interaction, specifically the less severe penetration of the Pd and Ce species into Al2O3, PdCe/Al2O3-CP showed higher Pd dispersion, specific surface area, pore volume and size than PdCe/Al2O3-Imp. The presence of more abundant reactive Pd0, and the higher accessibility of the active Pd and CeO2 sites, together with improved redox properties and enriched oxygen vacancies contributed much to the enhanced three-way catalytic activity of PdCe/Al2O3-CP. Additionally, simultaneously optimizing the Pd distribution and the CeO2–Al2O3 combination in a single step, as reported in this work, is also highly desirable in industry.
研究领域:
化学工程
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催化材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
NEW JOURNAL OF CHEMISTRY
·
2023
·Vol. 47
·期 21
·10397-10408
·
IF 3.3
Ning Gao,Xuanyu Gu,Jining Liu,Mengjie Fan,Yingwen Chen
At present, it is challenging to improve the activity and humidity resistance of ozone catalysts. Herein, an integrated MnOx–Al2O3 aerogel was prepared by a sol–gel method in this study, and its application in catalytic ozonation of toluene was explored preliminarily. Compared with the MnOx–SiO2 aerogel and impregnation catalysts (MnOx–silicalite-1 and MnOx–γ-Al2O3), the MnOx–Al2O3 aerogel exhibited superior performance in toluene removal and enhanced ozone utilization efficiency under optimal conditions (room temperature, O3 : C7H8 = 14 : 1, GHSV = 45 000 h−1 and 120 ppm C7H8). After reacting for 360 min, the 5 wt% MnOx–Al2O3 aerogel still showed stable catalytic ability, with the efficiency of toluene removal and ozone degradation maintained at 64.1% and 62.7%, respectively. Based on SEM characterization, the MnOx–Al2O3 aerogel demonstrated low MnOx agglomeration. From XPS and NH3-TPD analyses, it was found that the catalyst had a high content of Mn3+/Mn, Oβ/O, oxygen vacancies and acid sites, which was positively related to ozone degradation. Among them, an increase in the number of weak acid and moderately strong acid sites could prolong the life of active oxygen, which was the key to promoting the deep oxidation of toluene effectively. In addition, the MnOx–Al2O3 aerogel exhibited remarkable load-adjustability and humidity resistance. Therefore, the development of aerogel catalysts for catalytic ozonation of toluene is an effective strategy to alleviate the current ozone catalyst problem.
研究领域:
环境科学
·
催化材料
✓ 已验证
DOI
高影响因子
STEEL RESEARCH INTERNATIONAL
·
2024
·
IF 1.9
Li Zhang,Hang He,Lei Zhang,Yongqi Sun,Xu Gao,Jie Zeng,Wanlin Wang
Viscosity is an important property for CaO-SiO 2 -Al 2 O 3 -based slag systems, which showcases different scenarios in basic and acid slag systems with temperature change. This article elucidates the mechanism of their difference in viscosity–temperature property from melt structure. Results reveal that basic slag shows a low degree of polymerization (DOP) and a low viscosity of the melt due to an excessive O 2− ions depolymerizing the complex network structures, resulting in more low-polymerized Q 0 (Si) units and less high-polymerized Q 3 (Si) units. With the temperature decreases, the DOP and viscosity do not change significantly. However, the low DOP and viscosity favor crystal precipitation in the melt, leading to a solid–liquid mixed state of the slag, and thus a sharp increase in viscosity when the temperature decreases to 1275 °C. For acid slag, it undergoes a transformation into aluminosilicate structures with the introduction of numerous [AlO 4 ] 5− tetrahedra, accompanied by a significant increase in the relative mole fraction of high-polymerized Q 3 (Si) units. Consequently, the DOP and viscosity are obviously higher than that of the basic slag. Furthermore, the DOP and viscosity of the acid slag increase continuously with the temperature decreasing, thus impeding crystal precipitation and enhancing the glass transition tendency of the molten slag.
研究领域:
材料科学
·
冶金学
✓ 已验证
DOI
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2022
·
IF 7.139
Pan Li,Xinbao Li,Ye Yuan,Yang Wang,Pengfei Shen,Xinbo Zhu,Yingying Zhu
Steam reforming of bio-oil for hydrogen production is a promising green technology. Acetic acid was used as the bio-oil model compound. Experimental and density functional theory calculations were carried out to study the performance of Co/Al 2 O 3 catalysts doped with boron (B) with a 1 wt.%–5 wt.% content. Catalyst characterization by BET, XRD , XPS , NH 3 -TPD, H 2 -TPR, TEM, and TG-DTG was performed. We found that the catalyst performance improved significantly by B doping. Under the reaction conditions of T = 500 °C, steam-to-carbon ratio (S/C) = 5, and liquid hourly space velocity (LHSV) = 4.3 h −1 , the catalyst with a B doping ratio of 1 wt.% had the highest hydrogen yield of 85% and a maximum acetic acid conversion rate of 95%. The corresponding hydrogen productivity was 0.8 mmol/min. The stability of this catalyst exceeded 29 h. Density functional theory calculations showed that the interactions between the reaction intermediates and the surface were strengthened with B addition.
研究领域:
化学工程
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材料科学
·
催化反应
✓ 已验证
产品关联
DOI
高影响因子
SOLID STATE SCIENCES
·
2024
·
IF 3.4
Meng-Jie Cui,Imran Muhammad,Jian Feng,Tie-Zhen Ren
The crystal and particle size distribution of α-alumina (α-Al 2 O 3 ) nanoparticles is increasingly important for their potential application. However, it is difficult to produce α-Al 2 O 3 nanoparticles due to the high activation energy barrier making it difficult to obtain a pure α-Al₂O₃. In this paper, α-Al 2 O 3 nanoparticles with an average size of 60 nm in width and about 100–300 nm in length were prepared using isopropanol through thermal treatment at 1200 °C, accompanied by a minor fraction of the θ phase. Addressing the challenge of achieving pure phase α-Al 2 O 3 , Density Functional Theory (DFT) calculation was conducted to explore the energy landscape similarity between the θ and α crystal phases. The results provided valuable insights into obstacles associated with obtaining pure α-Al 2 O 3 , enlightening the relationship between surface electronegativity and crystal phases. Furthermore, X-ray Photoelectron Spectroscopy and electrochemical tests were employed to demonstrate that the α phase could enhance the surface electronegativity of Al 2 O 3 . This comprehensive study not only encompasses the synthesis of Al 2 O 3 nanoparticles but also elucidates the distinctions between α and θ phases. These results offer valuable insights into methods optimizing for the synthesis of pure phase α-Al₂O₃.
研究领域:
材料科学
·
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）