JOURNAL OF THE BRAZILIAN CHEMICAL SOCIETY
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2019
·Vol. 30
·期 2
·359-370
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IF 1.335
Zheng Zhi,Lei Tong,Wang Jun,Wei Yi,Liu Xuejun,Yu Fengwen,Ji Jianbing
In this paper, we report the catalytic cracking of soybean oil for biofuel over γ-Al2O3/CaO composite catalysts. The influence of catalysts, cracking temperature and weight hourly space velocity (WHSV) on the products distribution were investigated. The maximum yield (70.0 wt.%) of biofuel with low acid value (6.7 mg KOH g-1) and oxygen content (5.6%), as well as high calorific value (44.2 MJ kg-1) was achieved over 35 wt.% γ-Al2O3/CaO at 480 ºC and 3.72 h-1. The paper focused on the variation of biofuel composition and cracking pathway caused by γ-Al2O3/CaO composite catalysts via gas chromatography-mass spectrometry (GC-MS) and thermogravimetric (TG) analysis. Calcium oxide would react with fatty acid to yield calcium carboxylates at 300-350 ºC, which were subsequently decomposed into hydrocarbons (57.9 wt.%) and ketones (22.6 wt.%) at 415-510 ºC. As for 35 wt.% γ-Al2O3/CaO, the addition of γ-Al2O3 was beneficial to generate alkenes (38.2 wt.%), arenes (10.6 wt.%) and alcohols (12.3 wt.%) with ketones decreasing (16.5 wt.%) via γ-hydrogen transfer reaction and disproportination.
研究领域:
化学工程
·
可再生能源
·
催化材料
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DOI
高影响因子
FUEL
·
2021
·
IF 6.609
Jiandong Hong,Yanfeng Zhao,Jiang Wu,Xialin Xie,Pengcheng Zhao,Shuai Li,Hong Yao,Guangqian Luo,Zhenhao Liu,Xin Yang
Calcium oxide (CaO), as a high temperature sorbent, has been widely applied in the field of heavy metal removal due to its low price and stable chemical properties, but CaO tends to sinter at high temperature, which affects the adsorption performance. In this work, Al 2 O 3 /CaO sorbent with resistance to sintering was synthesized via citric acid and calcine method, which was innovatively employed to the adsorption of As 2 O 3 combining experiment and theoretical analysis. The experimental results demonstrate that the adsorption capacity of untreated CaO reduces immensely with the temperature rising from 1073 to 1273 K, and arsenic adsorption capacity reduces from 303 to 50 mg/kg. Whereas, arsenic adsorption capacity of Al 2 O 3 /CaO almost maintains at high level and reaches to 534 mg/kg at 1173 K, which proves that the addition of Al 2 O 3 can improve the anti-sintering ability of CaO. Meanwhile, through density functional theory (DFT), the adsorption sites of Al 2 O 3 /CaO was further studied. Al site of Al 2 O 3 /CaO was found to be the main adsorption active site and electron transfer channel, which effectively facilitates the separation of lattice oxygen. Finally, the adsorption mechanism of As 2 O 3 on Al 2 O 3 /CaO was proposed.
研究领域:
环境科学
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材料科学
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DOI
高影响因子
INFRARED PHYSICS & TECHNOLOGY
·
2024
·
IF 3.1
Yin Liu,Jie Wan,Yongbao Xiao,Dechao Yu
Glass forming regions of Al 2 O 3 -CaO-SrO (AlCaSr) system were systematically studied and clearly depicted by a combination of thermodynamic calculation method and traditional melt-quenching experiments. The glass forming region was first found with a composition range of Al 2 O 3 : 12–32 mol%, CaO: 43–68 mol%, and SrO: 20–36 mol%. Moreover, two representative glass compositions, 26.6Al 2 O 3 -49.4CaO-24SrO (AlCaSr-1) and 17.48Al 2 O 3 -58.52CaO-24SrO (AlCaSr-2), in central part of the experimental glass forming region and the corresponding glass doped with 1 mol% Er 2 O 3 , i.e., AlCaSr-1-Er and AlCaSr-2-Er, were selected and carefully prepared in our lab. Detailed investigations proved that the AlCaSr glasses had excellent comprehensive properties with high T g temperature (∼ 800 °C), wide transparency wavelength range (0.3–6 μm), and low maximum phonon energy (∼ 770 cm −1 ), and good 2.7 μm mid-infrared emitting properties via doping Er 3+ activators. These results highlight the potential application of AlCaSr glasses as infrared materials, and could benefit the development of high-performance infrared glasses.
研究领域:
材料科学
·
光学
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DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2025
·
IF 6.3
Zhitao Shan,Yuanyuan Kang,Jiayan Zhang,Yanfei Zhang,Qiuju Zheng,Shujiang Liu,Haizheng Tao,Yuanzheng Yue
The hardness ( H v ) and crack initiation resistance ( C R ) of oxide glasses are crucial properties for various applications, such as in vehicles, display devices, and buildings. However, these properties are still limited for many special applications. Here, we studied the evolution of the H v and C R with varying the ratio R = [Al 2 O 3 ]/[CaO] in the low silica (0 and 17 mol% SiO 2 ) aluminate glasses, i.e., so called silico-aluminate glasses, and thereby identified a composition that exhibits the highest C R and H v . The results showed that the H v decreased with increasing R within the peraluminous region. Furthermore, a significant increase in C R value with increasing R was detected in the range of R = 1.0–1.18. In contrast, the glass series containing 50 mol % SiO 2 content exhibited only a slight increase in C R value, but pronounced increases in both T g and H v with increasing R in the peraluminous region. The Raman spectroscopy revealed that [5]Al and oxygen tri-cluster ([3]O) are the controlling factors for C R and H v of the studied glasses. Moreover, the impact of [3]O and [5]Al on H v and C R is highly dependent on the SiO 2 content in the studied glasses.
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高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2021
·
IF 5.302
Qi Li,Jianliang Xie,Jin Hu,Xin Wang,Chengyong Yu,Shaoliang Jiang,Peng Liu,Chengli Sun,En Li,Longjiang Deng
The dielectric layer plays a key role in regulating electromagnetic wave broadband scattering based on meta-surface technology. Herein, the physical properties of composite powder, prepared by spray drying of CaO-B 2 O 3 -SiO 2 (CBS) glass-ceramic powder and Al 2 O 3 in different mass ratios, are systematically investigated. Meanwhile, a high enthalpy atmospheric plasma spraying equipment is utilized to prepare CBS/Al 2 O 3 composite coatings , and the morphology, physical properties and dielectric properties of the composite coating are analyzed. The XRD and DSC data of the composite coating reveal that the crystallization behavior of β-CaSiO 3 and CaB 2 O 4 gradually disappear with the increase of Al 2 O 3 content. Hence, only CaAl 2 Si 2 O 8 phase is observed during heat treatment. The experimental results confirm that the dielectric properties of CBS/Al 2 O 3 composite coating conform to the rule of mixture for composite materials. Also, the dielectric properties are affected by porosity and crystallization rate.
研究领域:
材料科学
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电磁工程
·
涂层与薄膜
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复合材料
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DOI
高影响因子
CERAMICS INTERNATIONAL
·
2023
·
IF 5.2
Hang Liu,Shengqiang Song,Rundong Jing,Mithun Nath
Recently, in the Al 2 O 3 –CaO–Cr 2 O 3 system, a Cr 3+ ternary phase named wuboraite (CaAl 2 Cr 2 O 7 ) was synthesized for the first time in an air atmosphere, which later showed an undetermined hint of solid solubility between Cr 3+ and Al 3+ in different atmosphere. In the present investigation, the solubility limits (or x values) of the CaAl 2± x Cr 2± x O 7 were determined by conducting high-temperature equilibrium experiments in both air and N 2 atmospheres with the various proportionate mixtures of CaO, Al 2 O 3 , and Cr 2 O 3 , and subsequently using powder X-ray diffraction (XRD) and scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) analysis. In the air atmosphere, the Cr richest end-member of the Wuboraite solid solution phase is CaAl 1.77 Cr 2.23 O 7 (or x = 0.23), while that of Al richest end-member is CaAl 2.18 Cr 1.82 O 7 (or x = 0.18). Whereas, in the N 2 atmosphere, the Cr richest end-member of the wuboraite solid solution phase is CaAl 1.77 Cr 2.23 O 7 (or x = 0.23), while that of Al richest end-member is CaAl 2.15 Cr 1.85 O 7 (or x = 0.15).
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高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2023
·
IF 5.7
Hang Liu,Shengqiang Song,Pin-Wen Guan,Guixuan Wu,Mithun Nath
Despite great potential in several applications, the pseudo-ternary system Al 2 O 3 –CaO–Cr 2 O x is an overlooked phase diagram due to the formation of a few toxic, carcinogenic, and water-soluble Cr 6+ compounds. In the research paper, equilibrium experimentation of selected compositions was conducted at 1073, 1373, and 1673 K and investigated using XRD , SEM-EDS, and leaching tests. Further, thermodynamic modeling of limited databases of the pseudo-ternary system Al 2 O 3 –CaO–Cr 2 O x was validated using DFT calculations. Including the recently discovered novel phase CaAl 2 Cr 2 O 7 (wuboraite), the seven phases not available in the SGTE SUBstance (SSUB) database, along with the CaCrO 4 and CaCr 2 O 4 phases existing therein, were modeled using Density Functional Theory (DFT). Based on the above experiments and the present CALPHAD model, we have calculated the isothermal sections (1073, 1373, and 1673 K) of the Al 2 O 3 –CaO–Cr 2 O x system for different oxygen partial pressures ( P (O 2 )= 0.21 atm and P (O 2 )= 10 −8 atm).
研究领域:
材料科学
·
化学工程
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产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2019
·
IF 3.45
Mithun Nath,Shengqiang Song,Hang Liu,Yawei Li
Despite huge potential, Al 2 O 3 –CaO–Cr 2 O 3 system has been one of the least investigated one due to the generation of carcinogenic and toxic Cr(VI) compounds. Herein, we investigated the system under air atmosphere varying Cr 2 O 3 while keeping Al 2 O 3 :CaO ratio constant in order to identify the Cr(VI) dominant region, eventually to avoid it. The Ca 4 Al 6 Cr VI O 16 phase predominantly formed in the air atmosphere with Cr 2 O 3 content up to ∼12 mol%. However, an unprecedented Cr(III) phase appeared under air at higher Cr 2 O 3 content (26.43 mol%). We then synthesized the new polycrystalline ternary Cr(III) compound (CaAl 2 Cr 2 O 7 ) at 1500 °C under air atmosphere for the first time. A trigonal symmetry of hexagonal crystal family with space group P3 (143), lattice parameters a = b = 7.7909 Å and c = 7.6506 Å were determined from the X-ray powder diffraction pattern study. Electron microscope studies revealed uniform hexagonal microcrystals with similar lattice parameters. Most significantly, the binding energies of 586.1 and 576.2 eV for Cr2p 1/2 and Cr2p 3/2 respectively implied the +3 oxidation state of Cr in this compound.
研究领域:
材料科学
·
化学
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DOI
高影响因子
CERAMICS INTERNATIONAL
·
2020
·
IF 3.83
Mithun Nath,Shengqiang Song,Ning Liao,Tengteng Xu,Hang Liu,Himansu Sekhar Tripathi,Yawei Li
Obtaining a stable Cr 3+ phase at higher temperatures in the presence of hydraulic calcium aluminates (the phases found in calcium aluminate cement, CAC) in the Al 2 O 3 –CaO–Cr 2 O 3 system remains a significant challenge in many application areas, as the formation of toxic, carcinogenic, and water-soluble Cr 6+ compounds often occur. To address the issue, recently, we synthesized a high-temperature stable Cr 3+ ternary compound (CaAl 2 Cr 2 O 7 ) with space group P3 (143). In the present work, we investigated the formation-stability of CaAl 2 Cr 2 O 7 with in-situ calcium aluminate phases at 1500 °C under the CO 2 atmosphere in the Al 2 O 3 –CaO–Cr 2 O 3 system through solid-oxide reactions route varying Cr 2 O 3 content (at constant Al 2 O 3 :CaO ratio). It co-existed with hydraulic calcium aluminates and other phases over the full investigated composition range of 2.76–68.3 mol% Cr 2 O 3 (5–80 wt%). Apart from CAC phases (CaAl 2 O 4 , CaAl 4 O 7 ), major Cr 3+ -phases are CaAl 2 Cr 2 O 7 and (Al,Cr) 2 O 3 while (α,β)-CaCr 2 O 4 and Ca(Al,Cr) 12 O 19 formed as minor phases. At a constant Al 2 O 3 :CaO ratio of 5.6:4.4 mol% (7:3 wt%), the formation of the CaAl 2 Cr 2 O 7 phase increases with Cr 2 O 3 content (up to the investigated composition of 26.43 mol%) and then decreases gradually. The solid solubility of Al and Cr in the CaAl 2 Cr 2 O 7 phase limited over a narrow range, and presumably dependent more on heat treatment condition rather than composition as reflected from the lattice parameter calculations. Though XRD revealed the presence of only Cr 3+ -phases in the partial CO 2 atmosphere, however, traces of Cr 6+ could be detected using XPS and leaching tests. However, leachable Cr 6+ content (0.095–1.252 mg/L) were much below the United States Environmental Protection Agency (US-EPA) permissible limit of 5 mg/L. The formation mechanism of the CaAl 2 Cr 2 O 7 and other phases with plausible reactions were also discussed.
研究领域:
材料科学
·
环境科学
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产品关联
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2021
·
IF 5.316
Xiaoyang Wang,Jianguo Huang,Hao Feng,Jinfeng Li,Zidie Pu,Xiangchun Yin
The hierarchical architecture constitutes one of the key factors affecting the performance of microwave absorbing materials (MAMs). Herein, core-shell Fe 3 O 4 with a dendritic hierarchical structure is fabricated successfully by the melting method in a SiO 2 -B 2 O 3 -Al 2 O 3 -CaO-Fe 2 O 3 multi-component system. The multiple transmission scattering absorption mechanism is mediated by the unique microstructure, thus improving the impedance matching and the microwave loss ability of the material. According to its reflection loss curve, the microwave absorption was efficiently optimized, yielding a minimum reflection loss (R L ) of − 54.26 dB when the thickness was 3.47 mm, and the effective bandwidth (R L <10 dB) for electromagnetic wave reflectance reached 3.28 GHz (6.48–9.76 GHz) with a sample thickness of 1.8 mm. The present work adds new useful information for the designing of high-performance glass-ceramic MAMs.
研究领域:
材料科学
·
电磁学
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产品关联
DOI
高影响因子
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