JOURNAL OF WUHAN UNIVERSITY OF TECHNOLOGY-MATERIALS SCIENCE EDITION
·
2018
·Vol. 33
·期 2
·381-388
·
IF 0.524
Shi Minxian,Chen Xia,Fan Shanshan,Shen Shirley,Liu Tianxiang,Huang Zhixiong
Fluxing agents of zinc borate, antimony oxide, galss frit A and glass frit B, with different melting or softening point temperatures, were added into MgO-Al 2 O 3 -SiO 2 /boron phenol formaldehyde resin (MAS/BPF) composites to lower the formation temperature of eutectic liquid phase and promote the ceramification of ceramifiable composites. The effects of fluxing agents on the thermogravimetric properties, phase evolution, and microstructure evolution of MAS / BPF composites were characterized by TG-DSC, XRD and SEM analyses. The results reveal that the addition of a fluxing agent highly reduces the decomposition rate of MAS / BPF composites. Fluxing agents lower the formation temperatures of liquid phases of ceramifiable MAS / BPF composites obviously, and then promote the ceramification and densification process. The final residues of composites are ceramic surrounded by large amount of glass phases.
研究领域:
材料科学
·
无机化学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING SCIENCE
·
2016
·
IF 2.75
Yi Li,Muhammad Nadeem Amin,Xingmei Lu,Chunshan Li,Fuqiang Ren,Suojiang Zhang
The catalyst NiO/MgO–Al 2 O 3 was prepared by loading magnesium and nickel onto the surface of γ-Al 2 O 3 beads, respectively, and was adapted to in situ upgrade the high temperature pyrolysis vapor derived from coal pyrolysis. The catalyst synthesis process, and structural variation were characterized by the XRD, SEM, and physical adsorption analyzer. In order to examine the catalytic effect on the different nickel loading ratio in the catalysts, the solid–liquid–gas product distribution, variation of gas and components of coal tar were studied by simulated distillation, GC/MS, elemental analysis and so on. The results shows both the tar yield and the content of the light fraction in the tar can be increased by catalytic up grade. The catalyst has a strong ability to convert the heavy component and polycyclic aromatic hydrocarbons in the tar to lower molecular weight components.
研究领域:
化学工程
·
能源科学
✓ 已验证
产品关联
DOI
高影响因子
CATALYSIS TODAY
·
2016
·
IF 4.312
Kun Jiang,Dong Sheng,Zihao Zhang,Jie Fu,Zhaoyin Hou,Xiuyang Lu
Mixed MgO–Al 2 O 3 (with different Mg/Al ratio) supported nickel catalysts were prepared via co-precipitation method and used for hydrogenation of levulinic acid to γ-valerolactone under mild condition. Characterization results indicated that mixed MgO–Al 2 O 3 supported Ni catalysts possessed bigger surface area than that of Ni/MgO and Ni/Al 2 O 3 , and Ni dispersed highly on the surface of mixed MgO–Al 2 O 3 support. It was found that mixed MgO–Al 2 O 3 supported Ni catalysts were more active and selective for the hydrogenation of levulinic acid to γ-valerolactone than that of Ni/MgO and Ni/Al 2 O 3 , and the best yield of γ-valerolactone at 160 °C, 1 h and 3 MPa H 2 reached 99.7% over Ni/MgAlO 2.5 , and Ni/Mg 2 Al 2 O 5 could be recycled without obvious loss of its initial activity.
研究领域:
化学工程
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
Crystals
·
2023
·Vol. 13
·期 8
·1261
·
IF 2.7
Zhen Pei,Haixiao Huang,Xingzhong Guo,Jinming Zhang,Mingxing Chen
MgO–Al2O3–SiO2(MAS) glass–ceramics with controllable crystalline phases were successfully prepared using the melting method followed by heat treatment. The effects of the main components of glass on the crystallisation kinetics, nucleation, crystallisation and properties of glass–ceramics were investigated in detail. As the Al2O3and MgO contents increase and SiO2content decreases, the crystallisation peak temperature and activation energy of MAS glass decrease, while the crystal growth tends to follow a homogeneous nucleation crystallisation. The MAS glass nucleation temperature and time increase with higher concentrations of Al2O3and MgO and with a lower SiO2concentration. Mg2(Al4Si5O18) indialite and MgAl2O4spinel precipitate simultaneously in the MAS glass after crystallisation; the relative proportion of crystalline phases is related to the composition and crystallisation temperature. A higher SiO2content allows the formation of a dominant indialite phase, while higher MgO and Al2O3contents promote the formation of a dominant spinel phase. The MAS glass ceramic with a greater indialite phase has good dielectric properties with a dielectric constant of 6.499 and dielectric loss of 0.0064, while that of a higher spinel phase possesses improved mechanical properties, with a Vickers hardness of 715 Hv and a bending strength of 244.9 MPa.
研究领域:
材料科学
·
无机化学
✓ 已验证
产品关联
DOI
高影响因子
FUEL PROCESSING TECHNOLOGY
·
2020
·
IF 4.982
Muhammad Masood Khan,Lijun Jin,Muhammad Mahmood Khan,Yang Li,Hammad Saulat,Yun Zhang,Muhammad Sarfraz,Jialong Zhu,Haoquan Hu
The composite catalysts AC-Ni/MgO-Al 2 O 3 were prepared by the co-precipitation method with activated carbon (AC) and [Ni,Mg,Al]-hydrotalcite as the precursors, and characterized by XRD , TG-DTG, N 2 adsorption, H 2 -TPR and SEM, respectively. The resultant catalysts were examined for CO 2 reforming of methane. The results showed that the introduction of AC into Ni/MgO-Al 2 O 3 catalyst improved the textural properties, especially the surface area and pore volume of mesopores , and decreased the size of metal Ni. Compared with Ni/MgO-Al 2 O 3 , the composite AC-Ni/MgO-Al 2 O 3 exhibited higher catalytic activity , stability and H 2 /CO ratio. But the AC content obviously influenced the catalytic performances. High AC loading resulted in the decline of catalytic activity owing to lower surface area and fewer active Ni content in the catalyst. 10AC-Ni/MgO-Al 2 O 3 with 10% AC displayed the best catalytic activity and stability compared with Ni/MgO-Al 2 O 3 . About 86.2% conversion of CH 4 , 91.3% conversion of CO 2 and above 0.95 ratio of H 2 /CO were achieved over 10AC-Ni/MgO-Al 2 O 3 sample for the reaction time of 5430 min. This work provides a route to improve catalytic performances of Ni-based catalysts in CO 2 reforming of methane.
研究领域:
化学工程
·
催化科学
✓ 已验证
DOI
高影响因子
MATERIALS CHEMISTRY AND PHYSICS
·
2016
·
IF 2.101
Dong Feng,Xudong Luo,Guodong Zhang,Zhipeng Xie
In order to determine the relationship between the property of MgOAl 2 O 3 SiO 2 composite ceramics and molar ratios of MgO/Al 2 O 3 , especially the sintering behavior and thermal shock resistance, the MgOAl 2 O 3 SiO 2 composite ceramics were fabricated with micro-size MgO , Al 2 O 3 powder and nano-size SiO 2 as main raw materials. The sample was characterized by phase analysis, densification and thermal shock times. Moreover, field emission scanning electron microscope was also conducted to study microstructure of the samples before and after thermal shock. Effect of different molar ratios of MgO/Al 2 O 3 on the sintering behavior and thermal shock resistance of composite ceramics were investigated. The results showed that the sample possess better sintering behavior and thermal shock resistance with the molar ratio of MgO/Al 2 O 3 equal to 2/1. Grains of periclase and spinel were directly bonded together, resulting in a dense and compact microstructure, and the bulk density of obtained sample reached 3.4 g/cm 3 . The microstructure of sample after thermal shock revealed that the crack propagation path was deflected and bifurcated, the main-crack propagation was restricted and more fracture energy was consumed, the thermal shock resistance of composite ceramics was greatly improved.
研究领域:
材料科学
·
陶瓷工程
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2022
·
IF 8.035
Qiangqiang Xue,Huilin Yi,Zhengwen Li,Zhao Jiang,Meng Chen,Yujun Wang,Binhang Yan,Guangsheng Luo
Surface modification of 600-µm-sized monodisperse gamma-alumina microspheres into magnesium–aluminum spinel, and co-impregnation-based loading of Rh–Ni (0.46 wt% Rh, 9.03 wt% Ni) were performed to synthesize catalysts for diesel-steam-reforming to hydrogen. The intimate interactions between Rh and Ni, the formation of the Rh–Ni alloy, and the Rh-doping-induced decrease in the particle size of Ni were determined. The DFT calculations results revealed that Rh-doped Ni(1 1 1) established remarkably weak bonds with oxygen-containing intermediates, and the reaction barrier of the rate-limiting step (CH 2 * + O* → CH 2 O*) on Rh–Ni(1 1 1) (0.76 eV) was lower than those of Ni(1 1 1) (1.14 eV) and Rh(1 1 1) (1.56 eV). The bimetallic catalyst shows the enhanced activity and resistance of sintering and carbon deposition compared with those of Ni-based (9.33 wt% Ni) and Rh-based (0.47 wt% Rh) catalysts. The catalytic performance of Rh–Ni-based catalyst was superior to that of physically mixed Ni-based and Rh-based catalysts at similar active metal loadings, which further confirmed the synergistic effect of Rh–Ni.
研究领域:
催化化学
·
能源材料科学
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
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2022
·
IF 5.532
Xufeng Zhang,Huidan Zeng,Xin Wang,Weichang Li,Lili Hu,Shubin Chen
MgO–Al 2 O 3 –SiO 2 glass-ceramics have been widely used in military, industrial, and construction applications. The nucleating agent is one of the most important factors in the production of glass-ceramics as it can control the crystallization temperature or the grain size. In this study, we investigated the effect of replacing P 2 O 5 with different amounts of TiO 2 on the crystallization, structure, and mechanical properties of an MgO–Al 2 O 3 –SiO 2 system. The crystallization and microstructure were investigated by differential scanning calorimetry , Raman spectroscopy , X-ray diffraction, scanning electron microscopy, and transmission electron microscopy . The mechanical properties were investigated by measuring the Vickers hardness , Young's modulus , and fracture toughness. The results showed that adding TiO 2 favored the precipitation of fine grains and significantly increased the Vickers hardness, Young's modulus, and fracture toughness of the glasses. Introducing an appropriate amount of TiO 2 can make a glass structure more compact, promote crystallization, and improve the mechanical properties of MgO–Al 2 O 3 –SiO 2 glass-ceramics.
研究领域:
材料科学
·
陶瓷学
·
玻璃科学
✓ 已验证
DOI
高影响因子
JOM
·
2022
·Vol. 75
·期 6
·1982-1992
·
IF 2.597
Qiu Yuchao,Shi Junjie,Hou Changle,Dong Jingjing,Zhai Yumo,Li Kaixuan,Yan Sen,Yu Kai,Li Jianzhong,Liu Changsheng
The spinel and pseudobrookite type ceramic materials have been widely used in different industries including ceramics, refractory and metallurgy. Therefore, their physicochemical properties are important for the development of related processes. In this regard, it is important to understand the formation principles of the spinel and pseudobrookite solid solutions. In the present work, the equilibrium phase relations for the MgO-Al 2 O 3 -TiO 2 system at 1700°C in air were experimentally determined by high-temperature equilibration-quenching technique followed by XRD and SEM–EDS analyses. The pseudobrookite solid solution was found to be coexisting with spinel solid solution and rutile phase, respectively. The composition evolution and formation principles of the pseudobrookite and spinel solid solutions were further elucidated from the corresponding crystal structures and composition relations. Furthermore, great discrepancies were observed when the 1700°C isotherm from the present work was compared with the isotherm simulated by FactSage 8.1. The evolution of the solid solution existing area was intuitively presented with reference to the experimental data from the literature. The results from present work are important for the development of spinel and pseudobrookite solid solution ceramics as well as the optimization of the thermodynamic database for oxide systems.
研究领域:
材料科学
·
陶瓷工程
·
热力学
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2019
·
IF 8.355
Jinchen Ma,Daofeng Mei,Weiwei Peng,Xin Tian,Danyan Ren,Haibo Zhao
Calcium looping (CaL) is extensively used in post-combustion capture of CO 2 and sorption-enhanced steam methane reforming because of its advantages of low cost and theoretically high CO 2 -capture capacity. Despite this, unstable reactivity of sorbent (CaO) and significant heat requirement for CaCO 3 calcination were always encountered in CaL. To address the aforementioned issues, a core-shell structured CaO-CuO/MgO@Al 2 O 3 sorbent (CCMA for short) was synthesized via the self-assembly template synthesis (SATS) method, and systematically investigated in terms of carbonation, calcination-reduction and oxidation cycles. In comparison to wet-mixing CaO-CuO material (CC), MgO-supported CaO-CuO (CCM) and Al 2 O 3 -supported CaO-CuO (CCA), the CCMA performed the highest CO 2 uptake capacity, which was quite stable at around 0.08 [g CO 2 ∙(g material) −1 ] in the 30 cyclic tests. In calcination-reduction stage, CaO in CCMA can be fully recovered by the decomposition of CaCO 3 , meanwhile the corresponding heat requirement can be compensated by the exothermic reaction between CuO and CH 4 , i.e., thermal neutrality can be achieved by using CCMA. The Cu in reduced CCMA can be subsequently oxidized back to CuO in the oxidation stage with a conversion of 97–98%, which is much higher than CC, CCM and CCA. After cycles, no serious sintering was observed for the CCMA and the measured crushing strength (1.4 N) was sufficient for fluidization, which, in combination with its high reactivity, makes this material very promising for CaL-CLC process.
研究领域:
能源科学
·
材料科学
✓ 已验证
DOI
高影响因子
Journal of Materials Research and Technology-JMR&T
·
2023
·
IF 6.4
Songtong Xuan,Yuming Tian,Xiangchen Kong,Jianying Hao,Xiaojun Wang
The tuning of the properties of MgAl 2 O 4 -based materials has aroused great attention in the field of engineering technology. Along these lines, magnesia and alumina were used as raw materials to prepare spinel by the solid-phase sintering method at 1500–1600 °C. Particularly, the impacts of the different MgO/Al 2 O 3 molar ratios on the microstructural densification, sintering process and mechanical property of the fabricated materials were systematically studied. The results showed that the stoichiometric spinel with the highest concentration of ion diffusion possessed the best densification. And the magnesium-rich spinel displayed the better densification following with the formation of solid-solution, while the aluminum-rich spinel exhibited the worst ability in forming the solid-solution. Moreover, the different molar ratios changed the microstructure of the spinel, which induced the optimal sintering temperature of stoichiometric spinel to be at least 50 °C below that of the others. Specifically, in stoichiometric spinel, spinel grains grew up and formed obvious structure, which made the sintering process arrive at the end point and made the performance reach the best. Specifically, the flexural strength was 112.62 MPa and apparent porosity was 0.44%. However, no grown or developed spinel grains were observed for magnesium-rich/aluminum-rich spinels, which delayed the sintering process.
研究领域:
材料科学
·
无机非金属材料
·
陶瓷工艺学
·
固态化学
·
结构陶瓷
✓ 已验证
DOI
高影响因子
Journal of Environmental Chemical Engineering
·
2023
·
IF 7.7
Feng Shi,Hongyuan Wang,Yifei Chen,Yanling Lu,Defa Hou,Can Liu,Yi Lu,Xu Lin,Xiaoqin Yang,Zhifeng Zheng,Yunwu Zheng
To develop an efficient and feasible catalyst for converting inedible vegetable oil to green biodiesel via a one-step decarboxylation process, a series of Ni-based MgO-Al 2 O 3 catalysts with different active Ni species were fabricated by adjusting the various Ni loading amounts (2.5–20%) and applied to the catalytic deoxygenation of OA to generate green biodiesel. Additionally, the structure-property relationship, deactivation mechanism and regeneration performance were also evaluated via various characterization technologies (XRD, BET, NH 3 -TPD, H 2 -TPR, XPS, SEM-EDX, HRTEM, TGA, Raman as well as GC/MS and UV-fluorescence spectra). The experimental results indicated that Ni introduction obviously enhanced the conversion ratio. Ni (10%)/MgO-Al 2 O 3 catalysts exhibited excellent catalytic performance with the highest HCs (95.12%), olefin content (57.37%) and green biodiesel content (75.90%) due to mild Brønsted-rich acidity sites, lower reduction temperature, higher active metallic Ni species content, suitable oxygen vacancy content and favorable texture properties via the decarbonylation reaction pathway. Furthermore, lower Ni loading was beneficial to gasoline and bioaviation fuel generation due to higher Brønsted-rich acidity sites and total acid amount, which boosted C-C scission by cracking reaction, and higher Ni content facilitated biodiesel formation. Additionally, Ni (10%)/MgO-Al 2 O 3 catalysts showed excellent reusability and regeneration due to Ni active species, but these advantages were slightly decreased (HCs: from 95.12% to 61.63%; biodiesel: from 75.90% to 57.52%) due to coke deposition and metal active species leaching and oxidation .
研究领域:
化学工程
·
可再生能源
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）