Magnesium Dichloride Research Articles

Development, characterization and themo-physical analysis of energy storage material doped with TiO2 and CuO nano-additives

The paper presents the results of an experimental investigation on chemical stability, surface morphology, and thermo-physical properties of phase change material integrated with nano additives. The research aims to evaluate impact of varying nano-particle concentration on thermal performance of phase change material. The phase change material magnesium dichloride hexahydrate and potassium chloride mixed in different mass ratio along with different wt% concentration of nano-additives titanium dioxide and copper oxide to prepare novel phase change material. Characterization methods such as Fourier Transform Infrared Spectroscopy, Scanning electron microscope, Energy-dispersive X-ray analysis, and Differential scanning calorimeter analysis were employed. The Fourier transform infrared spectra indicated physical interactions between phase change material and nano-additives, while Energy-dispersive X-ray analysis confirmed elemental composition, and Scanning electron microscope demonstrated uniform distribution. The improved thermal properties of samples were reflected in their phase change enthalpy (284.57 J/g to 324.63 J/g), minimal energy loss (0.91 %–2.96 %), and low supercooling (0.3 %–5.26 %). Notably, doping with 1.5 wt% of titanium dioxide and copper oxide enhanced thermal conductivity by up to 117.07 % and specific heat capacity by up to 48.09 %. The introduction of nanoparticles significantly improves heat transfer characteristics, resulting in enhanced energy retention, reduced energy loss during phase transitions, decreased supercooling, and increased physical stability. These results suggest that optimized phase change material with nano-additives is highly effective for applications requiring stable and efficient thermal management.

Study of the interaction of diethyl 2,3-diisobutyl succinate (DIBS) with magnesium dichloride and the stereoisomeric configuration of DIBS within titanium-magnesium catalysts of propylene polymerization

It was found by chromatography and 13C NMR spectroscopy that diethyl 2,3-diisobutyl succinate (DIBS), which is used as a stereoregulating electron donor in titanium–magnesium catalysts, exists as rac and meso stereoisomers. Their molecular structure was calculated using the DFT method. It was ascertained that mainly rac-DIBS is anchored to the surface of MgCl2. Subsequent interaction between the MgCl2/DIBS sample and TiCl4 leads to further removal of meso-DIBS. Titanium–magnesium catalysts of composition MgCl2/DIBS/TiCl4 prepared by different procedures contain 85–91% rac-DIBS. The IR spectroscopy data on the stereoisomeric configuration of DIBS in MgCl2/DIBS samples and titanium–magnesium catalysts MgCl2/DIBS/TiCl4 prepared by different procedures and the data on propylene polymerization over these catalysts are presented.

Spin-selective transport in edge-passivated zigzag magnesium dichloride nanoribbons: Towards bipolar spin diode and spin rectification devices

In the present work, we investigate the electronic, magnetic, and spin transport properties of zigzag MgCl2 (ZMgCl2) nanoribbons with different types of edge passivation using first-principles calculations based on density functional theory and non-equilibrium Green’s function techniques. Our findings reveal that the ZMgCl2 nanoribbon with Cl edges (ClαClα) and Mg edges (MgMg) exhibits distinct properties depending on the type of passivation. Passivation with O and F on ClαClα edges transforms the nanoribbon into a magnetic semiconductor. Passivation with H and F on MgMg edges results in a semiconductor behavior, B passivation leads to a half-metal behavior, and O passivation to a magnetic semiconductor. Additionally, our transport simulations demonstrate that the ClαClα-F nanoribbon operates as a single spin filter under bias voltage. For the MgMg-B nanoribbon, the behavior varies depending on the magnetic configuration of the electrodes. In the parallel configuration, MgMg-B also functions as a single spin filter, whereas in the antiparallel configuration, it operates as a dual spin filter device. Overall, our results highlight the remarkable potential of two-dimensional MgCl2 for spintronics applications, emphasizing the influence of edge passivation on the electronic and transport properties of nanoribbons.

Exploring the Potential of Substituted and Defected Magnesium Dichloride Monolayers for Optoelectronic Applications

Exploring the Potential of Substituted and Defected Magnesium Dichloride Monolayers for Optoelectronic Applications

External donor modified Mg-Ti based Z-N catalyst system for synthesis of Ultrahigh molecular weight polyethylene

This study reported novel external donors Diethyl 2,2'-(dimethylsilanediyl) diacetate (DSD1), Diethyl 2,2'-(phenyl(methyl) silanediyl) diacetate (DSD2) and Diethyl 2,2'- (diisopropylsilanediyl) diacetate (DSD3) and triethyl borate (TEB) employed with magnesium dichloride supported Ti-based monoester (Mg-Ti-ME) and magnesium dichloride supported Ti-based diester (Mg-Ti-DE) catalyst for synthesis of Ultrahigh molecular weight polyethylene (UHMWPE). Furthermore, the catalyst was tested with different concentrations of chain-terminating agents to understand the effect on molecular weight. The results showed Mg-Ti catalysts using DSD1, DSD2, and DSD3 and TEB external donors had significantly increased molecular weight in the presence of external donors with decreases in catalyst activity, compared to donor-free catalyst systems. In addition, in the presence of chain terminating agent molecular weight decreases significantly with less effect on catalyst activity. The obtained polymer, thermal properties characterized through differential scanning calorimetry (DSC), morphology through a scanning electron microscope (SEM), particle size of resin through a particle size analyzer and molecular weight through viscosity-average molecular weights method.

Copolymerization of Ethylene with Alpha-Olefins over Supported Titanium–Magnesium Catalysts Containing Titanium Compounds in Different Oxidation and Coordination States

Data were obtained on the copolymerization of ethylene with α-olefins over supported titanium–magnesium catalysts (TMC) prepared on the same magnesium dichloride support but differing in the composition and oxidation state of titanium. The copolymerization kinetics of ethylene with 1-hexene over TMC of different compositions were studied. Data on the composition of the produced ethylene–1-hexene copolymers, their molecular weight distribution, thermophysical characteristics, and branching distribution were presented. The constants of ethylene–1-hexene copolymerization over catalysts with different compositions were calculated. The TMC containing only Ti(II) compounds as the active component exhibited increased copolymerizing ability compared to the conventional TiCl4/MgCl2 catalyst containing Ti(III) compounds as the active component. In addition, TMC with Ti(II) as an active component produces copolymers with a more uniform branching distribution. It was shown that the TMC containing isolated Ti(II) ions could be used to produce X-ray amorphous ethylene-propylene elastomers with a high yield.

Insight of polypropylene synthesis with high performance multidentate internal donor catalyst system

AbstractPropylene polymerization using magnesium dichloride (MgCl2) supported Ziegler–Natta (Z–N) system is a robust and preferred catalytic process for producing polypropylene (PP) grades. Herein, synthesis of polypropylene products is reported using MgCl2 supported multidentate (3,3,3′,3′‐tetramethyl‐2,2′,3,3′‐tetrahydro‐1,1′‐spirobiindane‐5,5′,6,6′‐tetracarbonate) Z–N pre‐catalyst. The catalyst performance evaluation over propylene polymerization found that multidentate Z–N pre‐catalyst has better hydrogen response with controlled isotacticity of PP products as compared to conventional bidentate Z–N pre‐catalysts. Melt rheology analysis showed higher loss modulus and storage modulus for ultra‐high molecular weight isotactic polypropylene (UHMWiPP) as compared to PP resins with medium molecular weight. Further, GPC analysis reveal medium to broad unimodal molecular weight distribution (MWD) of PP products produced with multidentate Z–N pre‐catalyst system.

A combined experimental and molecular simulation study on stress generation phenomena during the Ziegler-Natta polyethylene catalyst fragmentation process.

The morphology of particles obtained under different pre-polymerization conditions has been connected to the stress generation mechanism at the polymer/catalyst interface. A combination of experimental characterization techniques and atomistic molecular dynamics simulations allowed a systematic investigation of experimental conditions leading to a certain particle morphology, and hence to a final polymer with specific features. Atomistic models of nascent polymer phases in contact with magnesium dichloride surfaces have been developed and validated. Using these detailed models, in the framework of McKenna's hypothesis, the pressure increase due to the polymerization reaction has been calculated under different conditions and is in good agreement with experimental scenarios. This molecular scale knowledge and the proposed investigation strategy would allow the pre-polymerization conditions to be better defined and the properties of the nascent polymer to be tuned, ensuring proper operability along the whole polymer production process.

Catalytic reactions on magnesium dichloride clusters saturated by titanium tetrachloride

Magnesium dichloride, titanium tetrachloride, and triethyl aluminum are essential components in the Ziegler-Natta catalysts for olefin polymerization. We report a systematic computational investigation (M06-2X/def-TZVP level of theory, thus accounting for dispersion) of the thermodynamics of a sequence of catalytic reactions leading to ethylene polymerization in the absence of electron donors. The reactions are explored for a series of TiCl4-adsorbed magnesium dichloride clusters as a function of the adsorption site, involving (104)- and (110)-type ideal edge sites alongside with corners representing defect sites. The reactions comprise alkylation of TiCl4, reduction from Ti(IV) to Ti(III) and Ti(II), ethylene π-complexation to Ti(III), and chain growth. The polymerization process as a whole is shown to be strongly exergonic for all adsorption sites, with coordination numbers of the site mainly contributing to the reduction and π-complexation energies.

Saturation of Magnesium Dichloride Crystallites by Titanium Tetrachloride

Magnesium dichloride and titanium tetrachloride are key components of Ziegler–Natta polymerization catalysts. We report a systematic computational study at M06-2X/def-TZVP level, thus accounting for dispersion, on saturation of magnesium dichloride crystallites by titanium tetrachloride. The crystallites are represented by (MgCl2)n clusters of various sizes and shapes, with n = 4–94, and they show preference for (104)-type edges with five-coordinate Mg atoms. Preferred adsorption modes of TiCl4 upon full saturation of crystallite edges are identified, alongside with adsorption strengths and relative stabilities of the (MgCl2)n-(TiCl4)m products. Consistent with previous literature, both Ti and Mg have tendency of favoring octahedral six-coordination, which can be achieved at all surface sites, including corners, serving as representatives of defect sites on the MgCl2 surfaces. The adsorption strengths of TiCl4 are the strongest for crystallites having (110)-type edges with four-coordinate Mg atoms. The much higher reactivity of (110)-type edges compared to (104)-type edges leads to reversal of the stability order of the crystallites upon TiCl4 adsorption. Saturated (MgCl2)n-(TiCl4)m crystallites thus favor shapes rich in (110)-type edges.

Crystallization of metastable monoclinic carnallite, KCl·MgCl2·6H2O: missing structural link in the carnallite family.

During evaporation of natural and synthetic K-Mg-Cl brines, the formation of almost square plate-like crystals of potassium carnallite (potassium chloride magnesium dichloride hexahydrate) was observed. A single-crystal structure analysis revealed a monoclinic cell [a = 9.251 (2), b = 9.516 (2), c = 13.217 (4) Å, β = 90.06 (2)° and space group C2/c]. The structure is isomorphous with other carnallite-type compounds, such as NH4Cl·MgCl2·6H2O. Until now, natural and synthetic carnallite, KCl·MgCl2·6H2O, was only known in its orthorhombic form [a = 16.0780 (3), b = 22.3850 (5), c = 9.5422 (2) Å and space group Pnna].

Crystallographic Structural Elucidation of E. coli HU and a Four‐Way Junction

E. coli histone‐like HU protein binds with high affinity to DNA recombination intermediates, such as the Holliday junction, to facilitate prokaryotic DNA transcription, compaction, recombination, and replication. While previous Förster resonance energy transfer (FRET) studies have determined possible structural models of HU‐junction interaction, X‐ray crystallographic data is needed to confirm those models. Studies have shown that crystals can be obtained with a dodecamer junction complex. However, we believe that HU can also be successfully crystallized with J20, that is, a junction with 20 base pairs per strand. We believe that 20 base pairs per arm is sufficient in limiting the flexibility of our junction. Our investigation aims to determine the most favorable conditions for HU‐J20 crystallization by using various solvents, pH, and viscosities. In our study, we show that our HU samples are pure, nuclease‐free, and bind with high affinity to J20. In addition, we show that our J20 samples are at least 90% properly annealed via a non‐denaturing polyacrylamide gel. Moreover, we have observed the formation of small crystals in a few of our wells, primarily around pH 8.5 in 20% polyethene glycol with 0.2 M ammonium chloride, and 0.005 M calcium dichloride. Going forward, we will screen around our successful conditions with higher protein concentrations. We will also use magnesium dichloride solutions in addition to calcium dichloride solutions, as previous studies have shown that magnesium improves the stabilization of DNA. Upon the development of crystals, we hope to solve the structure of HU‐J20 via diffraction.Support or Funding InformationAmerican Society of Biochemistry and Molecular Biology Undergraduate Research Award, Wesleyan Math and Science Scholars Program, Wesleyan UniversityThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Synthesis of Perylene-Tagged Internal and External Electron Donors for Magnesium Dichloride Supported Ziegler–Natta Catalysts

We report on the synthesis of three perylene-tagged electron donors representing three major types – phthalates, diethers, and alkoxysilanes – which are of importance for the subsequent studies of MgCl2-supported Ziegler–Natta catalysts by means of laser scanning confocal fluorescence microscopy. The obtained products were unambiguously characterized, including by X-ray crystal structure analysis; their photophysical properties (absorption and emission spectra) were investigated as well. Additionally, a reliable and convenient protocol for the multigram synthesis of the required starting material – 3-bromo­perylene (PerBr) – was developed. The key step of this method was synthesis of trialkylsilyl-substituted perylenes, which were further separated by means of flash chromatography followed by conversion of the isolated 3-trialkylsilyl-substituted product to PerBr.

Adsorption of Titanium Tetrachloride on Magnesium Dichloride Clusters

Magnesium dichloride and titanium tetrachloride are key components in heterogeneous Ziegler–Natta olefin polymerization catalysis. We have determined the preferred binding modes of titanium tetrachloride on magnesium dichloride clusters at the M06-2X level of theory, thus accounting for dispersion. A systematic study was carried out to locate the lowest energy isomers of (MgCl2)n(TiCl4)m complexes. Altogether ca. 1000 complexes with n ranging from 1 to 19 and m from 1 to 13 were studied. In line with the previous literature, the results consistently show that adsorption of TiCl4 onto MgCl2 preferably leads to octahedral six-coordination for both Mg and Ti atoms. This can be achieved by mononuclear binding of TiCl4 and binuclear binding of Ti2Cl8 on (110) and (104) surfaces of MgCl2, respectively. The preferred octahedral six-coordination is also achieved by binding of TiCl4 on defect sites, of which the most striking example is trinuclear binding mode at corners of the clusters. Overall, the results highlight the relevance of multinuclear binding of TiCl4 on MgCl2.

A feasibility study for high-temperature titanium reduction from TiCl4 using a magnesiothermic process

The current industrial practice for titanium extraction is a complex procedure, which produces a porous reaction mass of sintered titanium particulates fused to a steel retort wall with magnesium and MgCl2 trapped in the interstices. The reactor temperature is limited to approx. 900 °C due to the formation of fusible TiFe eutectic, which corrodes the retort and degrades the quality of titanium sponge. Here we examine the theoretical foundations and technological possibilities to design a shielded retort of niobium-zirconium alloy NbZr(1%), which is resistant to corrosion by titanium at high temperature. We consider the reactor at a temperature of approx. 1150 °C. Supplying stoichiometric quantities of reagents enables the reaction in the gas phase, whereas the exothermic process sustains the combustion of the reaction zone. When the pathway to the condenser is open, vacuum separation and evacuation of vaporized magnesium dichloride and excess magnesium into the water-cooled condenser take place. As both the reaction and the evacuation occur within seconds, the yield of the extraction is improved. We anticipate new possibilities for designing a device combining the retort function to conduct the reduction in the gas phase with fast vacuum separation of the reaction products and distillation of magnesium dichloride.

Selective Extraction and Recovery of Nd and Dy from Nd-Fe-B Magnet Scrap by Utilizing Molten MgCl2

Fundamental experiments are conducted with the aim of developing an efficient recycling process for rare earth elements (REEs) from neodymium-iron-boron (Nd-Fe-B) permanent magnet scrap. Molten magnesium dichloride (MgCl2) was chosen as an extraction medium, which can selectively chlorinate and extract REEs in magnet alloys. Dysprosium-containing Nd-Fe-B magnet alloy was immersed in molten MgCl2 at 1273 K (1000 °C) for 3 to 12 hours. The results of the experiments clearly show that the REEs in the magnetic alloy were successfully extracted into the molten salt, while the Fe-B alloy remained in a solid form. The extraction ratios of Nd and Dy were at most 87 and 78 mass pct, respectively. After the extraction experiment, excess MgCl2 and Mg were removed by vacuum distillation and the rare earth chlorides were recovered. Thus, the feasibility of this method for efficient recovery of rare earths using molten MgCl2 is demonstrated.

Alkylation of titanium tetrachloride on magnesium dichloride in the presence of Lewis bases

We report the first quantum chemical description of the initial steps of Ziegler–Natta olefin polymerization catalysis involving all the relevant catalyst components. TiCl4 binds on the (104) surface of MgCl2 as a binuclear Ti2Cl8 and on the (110) surface as a mononuclear TiCl4, both binding modes being stabilized by octahedral six-coordination of Ti and Mg. Aluminum alkyl (triethylaluminum) coordinates to the MgCl2 surface via an unsaturated Cl to initiate catalyst alkylation reactions, thermodynamically driven by dimerization of the chlorinated aluminum alkyl. Addition of an internal donor (dimethyl phthalate) greatly stabilizes the (104) and (110) surfaces, ending up directing the alkylation reactions to the binuclear (104) site. External donor (dimethoxydimethylsilane) further assists the process, stabilizing similarly both catalytic surfaces. The spatial requirements of the donors are shown to be greater on the (110) surface than on the (104) surface, rationalizing the role of Lewis bases in the stereocontrol of polyolefins.

Magnesium dichloride effect in ethylene polymerization reactions: a comparative DFT study of Mg-containing and Mg-free post-titanocene catalytic systems

A DFT study of the bi- and trinuclear heterocomplexes of Ti, Al and Mg revealed a higher reactivity of Mg-containing compounds toward ethylene, as compared to Mg-free systems; this explains a significant activation effect of Mg-containing compounds on thecatalytic activity of the Ti complexes in ethylene polymerization.

DFT-D Investigation of Active and Dormant Methylaluminoxane (MAO) Species Grafted onto a Magnesium Dichloride Cluster: A Model Study of Supported MAO

Density functional theory calculations were carried out to study the interaction of various models for methylaluminoxane and the active and dormant species in polymerization with the (110) MgCl2 surface. MAO species may bind to the surface via Al–Cl, Mg–O, and Al−μ-CH3–Mg bonds. Our results suggest that the activity of supported MAO may be higher than of homogeneous MAO because the support stabilizes (AlOMe)n·(AlMe3)m, precursors to the active species in polymerization. Moreover, the support lowers the free energy of formation of species that are active in polymerization relative to those that are dormant. Finally, it may be that the support decreases the energy associated with the cation–anion separation in [Cp2ZrMe]+[Me(AlOMe)n]−, a species that is likely dormant in homogeneous processes, hinting that the support has the possibility of increasing the number of potentially active sites.

Preparation of UHMWPE/carbon black nanocomposites by in situ Ziegler–Natta catalyst and investigation of product thermo-mechanical properties

A new bi-supported Ziegler–Natta catalyst was prepared successfully by supporting TiCl4 on the carbon black (CB) and magnesium dichloride. Then, this catalyst was used to prepare ultrahigh molecular weight polyethylene (UHMWPE) nanocomposites via in situ polymerization. The effects of difference molar ratios of triisobutylaluminum as activator to TiCl4, polymerization temperature, pressure of monomer and polymerization time on productivity of the catalyst were studied. The maximum activity was obtained at [Al]/[Ti] = 121:1. Increasing monomer pressure raised catalyst activity. Increasing temperature to 60 °C increased the polymerization yield; however, the higher temperature decreased the productivity of the catalyst. Scanning electron microscopic images showed that homogeneous dispersion of CB nanoparticles in the polymeric matrix was achieved without any agglomeration of CB. The crystallization behavior was evaluated using differential scanning calorimeter. The results showed that the crystallinity degree of UHMWPE slightly increased with increasing of CB, indicating that the CB acted as hindrance and nucleating agent. Furthermore, with introducing CB to polymeric matrix up to 1.6 wt%, the melting temperature and crystallization temperatures were slightly increased. The thermogravimetric analysis showed that incorporation of CB has improved thermal stability of polymeric matrix compared to pure UHMWPE. Viscoelastic properties were also investigated using dynamic mechanical thermal analysis. Obtained results showed that with introducing CB, the storage and loss modulus were improved especially at low temperatures and the glass transition temperature was slightly altered. Significant incensement in mechanical properties of the polyethylene was observed by adding nanofiller, in the other words, the presence of CB considerably improved tensile strength, Young’s modulus, and yield stress.