SOLAR ENERGY
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2020
·
IF 4.608
Tingrui Xu,Xuejiao Li,Lili Guo,Feng Wang,Zhongfeng Tang
First principle molecular dynamics (FPMD) simulations in combination with experimental measurements are applied to investigate the phase transition behavior of NaCl-MgCl 2 eutectic salt from 823 to 573 K. First, the essential phase transition indexes of thermal expansion coefficient, density, melting point, and enthalpy of fusion for NaCl-MgCl 2 eutectic obtained by simulations and experiments are in good agreement with each other. Second, the micro-structural characteristics during phase transition are depicted by the temperature dependences of angular distribution function, radial distribution function and coordination number. The structural evolution of NaCl-MgCl 2 eutectic is illustrated from the rearrangement of polyhedral M g C l n 2 - n clusters, and it is founded that high and low temperature are conducive to the formation of 4-fold and 6-fold coordinated structure, respectively. Third, the ionic self-diffusion coefficients for NaCl-MgCl 2 eutectic are predicted and concluded that Mg 2+ behaves like a complex than as a free ion resulting in less diffusivity. Therefore, the shear viscosities of molten NaCl-MgCl 2 as well as the corresponding pre-exponential factor and activation energy are evaluated considering the solvodynamic mean radius of all the diffusive particles. Ultimately, two figures of merit for molten NaCl-MgCl 2 are deduced to evaluate the heat-transfer and heat-loss performance by integrating multiple thermal properties including density, viscosity, specific heat capacity and thermal conductivity. Overall, these simulation results are in satisfactory agreement with available reference data, indicating that the FPMD simulations work extremely well in predicting the thermophysical and structural properties of NaCl-MgCl 2 , which also provide insights for the applications of binary chloride salts in thermal energy storage.
研究领域:
材料科学
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计算化学
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产品关联
DOI
高影响因子
JOURNAL OF CHEMICAL AND ENGINEERING DATA
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2020
·
IF 2.369
Hongxia Li,Lijiang Guo
The solubility and phase diagram of the CsCl–MgCl2–H2O ternary system, at a relatively wide temperature range, are significantly important for the extraction of the cesium resources from salt lakes. The isothermal dissolve equilibrium (IDE) method was used to determine the solubility of this ternary system at T = 273.15, 308.15, and 348.15 K, which have not been reported yet. The measured results indicated that the equilibrium solid phases in this ternary system from T = 273.15 to 348.15 K are CsCl, double salt CsCl·MgCl2·6H2O, and MgCl2·6H2O, and correspondingly there are three crystal regions and two cosaturated points for these solid phases. The solubility of the salt increased with the increase of the temperature, and the double salt CsCl·MgCl2·6H2O and CsCl crystal regions also became larger with the increasing temperature. However, the crystal regions of the MgCl2·6H2O solid phase are not enlarged obviously. Based on the solubility and phase diagram of CsCl–MgCl2–H2O at different temperatures, the separation process of CsCl resources has been proposed.
研究领域:
化学
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材料科学
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DOI
高影响因子
Journal of Chemical Theory and Computation
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2024
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IF 5.7
Jia Zhao,Taixi Feng,Guimin Lu
The local structure and thermophysical properties of SrCl2–KCl–MgCl2 melt were revealed by deep potential molecular dynamicsdriven by machine learning to facilitate the development of molten salt electrolytic Mg–Sr alloys. The short- and intermediate-range order of the SrCl2–KCl–MgCl2 melts was explored through radial distribution functions and structure factors, respectively, and their component and temperature dependence were discussed comprehensively. In the MgCl2-rich system, the intermediate-range order is more pronounced, and its evolution with temperature exhibits a non-Debye–Waller behavior. Mg–Cl is dominated by 4,5 coordination and Sr–Cl by 6,7 coordination, and their coordination geometries exhibit distorted octahedra and distorted pentagonal bipyramids, respectively. A database of thermophysical properties of SrCl2–KCl–MgCl2 melts, including density, self-diffusion coefficient, viscosity, and ionic conductivity, was thus developed, covering the temperature range from 873 to 1173 K.
研究领域:
材料科学
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计算化学
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产品关联
DOI
PubMed
高影响因子
CELLULOSE
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2019
·Vol. 27
·期 2
·799-823
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IF 3.917
Lv Wei,Liao Yuhe,Zhu Yuting,Liu Jing,Zhu Changhui,Wang Chenguang,Xu Ying,Zhang Qi,Chen Guanyi,Ma Longlong
The cleavage of linkages of lignocellulose is important for its valorization. The linkage cleavage of cornstalk hydrolysis residue was investigated over catalysts (Ru/C + MgCl 2 ) in EtOAc/H 2 O solvents. The results show that almost hydrogen bonds, C–C bonds, ether and ester bonds in the matrix of lignin and cellulose were broken, accompanying 80.6% of lignin and 98.5% of cellulose conversion, and obtaining 37.5% of aromatic monomers and 28.8% of lignin oligomers. In the reaction system, biphasic EtOAc/H 2 O solvents exhibited an effect on cleaving the intermolecular linkages between lignin and cellulose. MgCl 2 showed limited abilities of breaking the α-O-4 and β-O-4 linkages in lignin and limited β-1, 4-glycosidic and hydrogen bonds in cellulose were cleaved over Ru/C catalyst. The cleavage of C–O linkages (α-O-4, β-O-4, 4-O-5) and C–C bonds (α-β, β-5) in lignin were mainly dependent on Ru/C catalyst. Much C–O and the stubborn C–C linkages of β-5, β-1 and 5-5 were significantly disrupted by the synergistic effect between MgCl 2 and Ru/C. However, MgCl 2 exhibited great contribution to breakage of β-1, 4-glycosidic linkage, hydrogen bonds and sugar ring of cellulose. The linkage of β-1, 4-glycosidic, hydrogen bonds and C–C in C5/C6 sugars were significantly broken. The increased yield of products was evidently due to the synergistic effect of Ru/C combined with MgCl 2 .
研究领域:
生物质化学
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催化化学
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产品关联
DOI
高影响因子
JOURNAL OF CHEMICAL AND ENGINEERING DATA
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2024
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IF 2
Chen Wang,Feng Wu,Yanfeng Sui,Guoxiong Wang,Tielin Wang,Jiayu Ma
The solubility of K2SiF6 in MgCl2 and FeCl3 solutions within a temperature range between 20 and 70 °C was experimentally determined by the static method under atmospheric pressure. The equilibrium solids obtained under various conditions were analyzed by XRD, SEM, and FTIR to confirm the stability of corresponding solid phases. The solubility of K2SiF6 in MgCl2 and FeCl3 solutions increased with increasing temperature and concentration, and K2SiF6 remained stable in MgCl2 and FeCl3 solutions. Moreover, the experimental data were successfully correlated with the Apelblat empirical equation. The thermodynamic properties of the solution process, including the Gibbs energy, enthalpy, and entropy, were calculated by the van’t Hoff analysis and the Gibbs equation. The dissolution process of K2SiF6 in the measured solutions was found to be endothermic and nonspontaneous. The findings above can provide fundamental data and theoretical support for optimizing the crystallization of K2SiF6 in acid leaching solution from phosphorus–potassium associated ore and preventing scale formation of K2SiF6 in wet-process phosphoric acid (WPA) vacuum filtration.
研究领域:
化学工程
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2022
·
IF 4.326
Shuaifeng Liu,Edouard Asselin,Zhibao Li
An industrially feasible process was proposed to produce α-calcium sulfate hemihydrate (α-HH) from FGD gypsum without any additives. In this process, an AlCl3 solution was used to promote the conversion of calcium sulfate dihydrate (DH) to hexagonal prismatic α-HH with high strength at atmospheric pressure. The phase transition kinetics of FGD gypsum was experimentally investigated under conditions: AlCl3 (2–2.5 m), MgCl2 (0–0.4 m) existing in raw FGD gypsum, and the solid–liquid ratio (or solid content %) range of 0.1–2 at 363 K. It was found that increasing the concentrations of MgCl2 in AlCl3 solution accelerated the conversion. The uniform large hexagonal prism HH product was obtained at the folowing optimal conditions: 2.5 mol/kg AlCl3, 0.4 mol/kg MgCl2, solid–liquid ratio of 2, and equilibration time of 2 h at 363 K. The phase diagram of the AlCl3-MgCl2-H2O system was determined by measuring solubility of solids. The E-NRTL activity model was used to construct the phase transition diagram of CaSO4 in AlCl3–MgCl2 media and to judge the stable range of DH and HH.
研究领域:
材料科学
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化学工程
✓ 已验证
DOI
高影响因子
INFRARED PHYSICS & TECHNOLOGY
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2018
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IF 1.851
Honghan Bu,Guoyue Xu,Chuyang Liu,Tengchao Guo,Shujuan Tan
The green BCG/MgCl 2 /PEG-g-CDA powders were synthesized at different temperatures via liquid-phase reaction method. The microstructures of the synthesized powders were analyzed and characterized by FT-IR, XRD and ChemDraw software. The effects of synthesized temperatures on infrared emissivity properties of the powders in the wavelength range 3–5 μm were investigated systematically. It is found that the powders heated at 100 °C exhibit the optimum crystallinity at room temperature and thus show the largest variation (0.4) in infrared emissivity with the test temperature varying from 50 °C to 65 °C. Furthermore, the mechanisms for the self-regulated infrared emissivity properties are also explored thoroughly. The variation of infrared emissivity with temperature is ascribed to the changes in resistivity, which is induced by the transformation of PEG-g-CDA between crystalline and amorphous as well as the molecular structure transition of BCG between quinone and lactone. Our results suggest that BCG/MgCl 2 /PEG-g-CDA powders are potential candidates for intelligent infrared camouflage.
研究领域:
材料科学
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光学
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化学工程
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产品关联
DOI
高影响因子
SOLAR ENERGY MATERIALS AND SOLAR CELLS
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2020
·
IF 6.984
Xuejiao Li,Na Li,Weihua Liu,Zhongfeng Tang,Jianqiang Wang
The first principle molecular dynamics (FPMD) simulations in combination with experimental measurements are applied to investigate the thermophysical properties and structural evolution of MgCl 2 –NaCl–KCl (MNK) eutectic . The densities, melting point, and enthalpy of fusion simulated by FPMD within NPT ensemble are consistent with experimental results. Besides, the thermal conductivity of molten MNK eutectic evaluated from FPMD simulations with NVT ensemble gives satisfactory result. Furthermore, the shear viscosities of MNK eutectic are deduced based on ion self-diffusion coefficients and solvodynamic radius, similar to the data estimated by additive contribution method. Eventually, the change rules of radial and angular distribution functions and structural factor of MNK eutectic during melting are revealed, and the melting mechanism is proposed from the evolution of polyhedral coordination structures. These results are heuristic in structure-activity relationship of MNK eutectic, which sheds insight for further development of efficient heat transfer and storage media through microstructure engineering.
研究领域:
材料科学
·
热物理
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产品关联
DOI
高影响因子
JOURNAL OF CHEMICAL AND ENGINEERING DATA
·
2023
·
IF 2.6
Yanjuan Zhang,Yadong Ning,Caixia Lv,Zhihui Yu,Yu Wang,Guangye Wei,Jingkui Qu
For efficient nickel recovery from laterite nickel ore, an improved understanding of the solubility in ternary MgCl2–NiCl2–H2O systems is required. Herein, the stable phase equilibria in a ternary MgCl2–NiCl2–H2O system at 303, 313, and 323 K were studied using an isothermal dissolution equilibrium method. For this ternary system, the solubility and density were measured at different temperatures. The equilibrium solid phases were identified using X-ray diffraction, combined with the Schreinemakers’ method for wet residues. Based on the solubility data, the phase diagrams of the MgCl2–NiCl2–H2O system at 303, 313, and 323 K were plotted. At all investigated temperatures, the phase diagrams of this ternary system presented an invariant point, two isothermal dissolution curves, and three crystallization regions. Neither double salt nor solid solution was produced. The Mixed Solvent Electrolyte (MSE) model was applied to calculate the solubility for this ternary system. According to the comparison of phase diagram, the calculated data were in good agreement with the experimental values.
研究领域:
化学工程
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材料科学
·
物理化学
✓ 已验证
DOI
高影响因子
POLYMER
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2024
·
IF 4.1
Qingtao Niu,Aihua He,Chongdian Si,Guodong Liu,Mingxuan Xiao,Guifan Chen,Manman Jin
Four TiCl 4 /MgCl 2 Ziegler-Natta catalysts (Cat-1∼Cat-4) with titanium contents in the range of 0.038–0.578 wt% were synthesized by the chemical rout and used for isoprene polymerizations. Four catalysts had similar possessed rod-like morphologies and their surface areas gradually increased as Ti contents increased. Cat-1 with the lowest Ti content (0.038 wt%) had the highest catalytic activity (28039.6 g∙P/(g∙Ti∙h)). To our knowledge, this was the highest activity achieved for isoprene polymerization using the heterogeneous TiCl 4 /MgCl 2 Ziegler-Natta catalyst. With the increasing Ti content, the catalyst activity gradually decreased in the order of Cat-1 < Cat-2 < Cat-3 < Cat-4, whereas the trans -1,4 stereoselectivity increased. Cat-4 with the highest Ti content (0.578 wt %) gave highest trans -1,4 units (97.7 mol%). The polymers were mainly composed of fraction C, D and G. C and D had high trans -1,4 structure while G fraction had low trans -1,4 structure. The plausible stereospecific transformation models of MgCl 2 -supported Ziegler-Natta catalyst with different Ti contents were discussed.
研究领域:
催化
·
高分子化学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
POLYMER
·
2021
·
IF 4.43
Qingtao Niu,Manman Jin,Aihua He,Tielong Chen,Guodong Liu,Chongdian Si
External electron donors (ED) play significant roles in regulating stereoselectivity and catalytic activity of MgCl 2 -supported (TiCl 4 /MgCl 2 ) type Ziegler-Natta catalysts. Investigating the contribution of ED on copolymerization of isoprene (Ip) and butadiene (Bd) with TiCl 4 /MgCl 2 Ziegler-Natta catalysts is little reported. Herein, we reported the effects of three alkoxysilanes including dimethyldimethoxysilane (DMDMS), diphenyldimethoxysilane (DPDMS), phenyltrimethoxysilane (PTMS) added as ED on trans -1,4 stereoselective copolymerization of Ip and Bd using TiCl 4 /MgCl 2 -triisobutylaluminium (Al(i-Bu) 3 ) catalyst system. Copolymers generated by TiCl 4 /MgCl 2 catalyst in the absence of ED featured the microstructure transformation from cis -1,4 and trans -1,4 mixed microstructure on initial stage to trans -1,4 dominated microstructure and the molecular weight ( M w ) evolution from low M w to high M w , indicating the transformation from low trans -1,4 stereoselective active center C*-1 to high trans -1,4 stereoselective active center C*-2. Appropriate introduction of alkoxysilane donors improved the polymerization activity, trans -1,4 unit content and molecular weight of copolymer in the order of PTMS > DPDMS > DMDMS, while excess alkoxysilane donors caused the decrease in that of polymerization behaviors. Increasing polymerization temperature also promoted the enhance in catalytic activity and trans -1,4 stereoseletivity of TiCl 4 /MgCl 2 catalyst in the presence of ED. The equilibrium between deactivation and activation effect strongly depended on alkoxysilane structure, concentration and temperature. Plausible mechanisms for stereoselective transformation of active centers in Ip and Bd copolymerization using MgCl 2 -supported type Ziegler-Natta catalyst were proposed in terms of special roles of ED.
研究领域:
高分子化学
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催化化学
✓ 已验证
产品关联
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2019
·
IF 3.375
Ting Li,Shuai Ma,Hu Yang,Zhen-liang Xu
Metal organic frameworks (MOFs) containing salt impurity provide a new idea for carbon material design. Presently, Mg–MOF/MgCl2 hybrid polycrystallines with different morphologies are solvothermally synthesized using 1,3,5-benzenetricarboxylic acid (BTC) or 1,4-benzenedicarboxylic acid (BDC) as the ligand, with or without polyethylene terephthalate (PET) inducer, respectively. After calcination, the products look like a flower, bud, cube, or nanosheet. When tested as adsorbent, the maximum methyl orange adsorption capacity reaches 3250 mg/g, the highest reported to date. The reason is attributed to the carbon-covered Mg salt inside the carbonized MOF. When tested as supercapacitor, carbonized MOFs based on BTC ligand show a high specific capacitance (127F/g) but a low rate capability, whereas a lower specific capacitance (121F/g) but a better rate capability (80% retention at 10A/g) are found for carbonized MOFs based on BDC. The reason is due to their different pore structures.
研究领域:
材料科学
·
化学
·
纳米技术
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环境科学
·
能源存储
✓ 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）