共查询到20条相似文献,搜索用时 343 毫秒
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新型催化剂载体材料—镁铝复合氧化物的制备及其物理化学性质 总被引:39,自引:2,他引:39
以NaOH,Na2CO3混合或以NH4OH,(NH4)2CO3混合液为沉淀制备了Mg/Al=3-6.7的Mg-Al为滑石。将水滑石在500-600℃下焙烧制得了具有与Mgo相同的晶体结构的Mg(Al)L复合氧化物,它们的比表面积大于或接近γ-Al2O3,而且具有良好的热稳定性。 相似文献
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用精密量热仪对模拟合成的MgO-27.56%MgCl-H2O浓盐溶液进行恒沸盐酸-△H滴定。发现活性MgO在27.56%MgCl-H2O溶液中不同浓度时表现出不同的结果。结合该浓盐溶液的恒混盐酸-PH滴定结果对反应机制进行了初步探讨。 相似文献
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四元体系CsCl—PrCl3—13%HCl—H2O(25℃)和CsCl—PrCl3—42%H… 总被引:1,自引:0,他引:1
测定了四元体系CsCl-PrCl3-13%HCl-H2O(25℃)和CsCl-PrCl3-42%HAc-H2O(30℃)的稳定平衡态的溶液数据,绘制了相应的溶度图,两个体系的皆中有4种固相,CsCl,PrCl3.6H2O2种原始盐和CsCl.PrCl3.6H2O,3CsCl.PrCl3.7H2O2种复盐,证实了文献中对Meyer反应1机理的解释,并对新相进行了热分析,X射线粉末衍射及偏光显微镜测定 相似文献
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三元体系MgCl2—CO(NH2)2—H2O在25℃时的等温溶度与新相 … 总被引:3,自引:1,他引:3
测定了25℃时三元体系MgCl2-CO(NH2)2-H2O的等温溶度及饱和溶液的折光率和密度,且绘制成溶度图和性质,组成图,在三元体系内形成2个三元化合物新相,MgCl2.CO(NH2)2.4H2O(记作A)和MgCl2.4CO(NH2).2H2O(记作B),B为新化合物,三元体系的溶度图由4支单饱和线(对应单饱和因相为MgCl2.6H2O,三元化合物A和B,CO(NH2)2)组成,这4支单饱和线 相似文献
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利用原位红外技术研究了CH3OH,CO,O2等在5%Ag/γAl2O3上的吸附情况及CH3OH和O2共吸附时表面物种的变化.结果表明,在表面纯净的Ag/γAl2O3催化剂上,甲醇的解离吸附仅发生在γAl2O3上;表面预吸附氧后,可大大增强Ag对CH3OH的解离吸附,当吸附的[CH3O]与[O]在Ag/γAl2O3上相互作用时,出现吸附态甲醛、甲二氧基、甲酸根等中间物种.O2在Ag/γAl2O3上存在非解离吸附(O-2),在真空中较易脱附,但在氧气氛下可于100℃时稳定存在. 相似文献
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Christine Rincke Horst Schmidt Gernot Buth Wolfgang Voigt 《Acta Crystallographica. Section C, Structural Chemistry》2020,76(8):741-745
MgCO3·MgCl2·7H2O is the only known neutral magnesium carbonate containing chloride ions at ambient conditions. According to the literature, only small and twinned crystals of this double salt could be synthesised in a concentrated solution of MgCl2. For the crystal structure solution, single‐crystal diffraction was carried out at a synchrotron radiation source. The monoclinic crystal structure (space group Cc) exhibits double chains of MgO octahedra linked by corners, connected by carbonate units and water molecules. The chloride ions are positioned between these double chains parallel to the (100) plane. Dry MgCO3·MgCl2·7H2O decomposes in the air to chlorartinite, Mg2(OH)Cl(CO3)·nH2O (n = 2 or 3). This work includes an extensive characterization of the title compound by powder X‐ray diffraction, thermal analysis, SEM and vibrational spectroscopy. 相似文献
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Dehydration is an important process which affects the chemical, physical and mechanical properties of materials. This article describes the thermal dehydration and decomposition of the Sorel cement phase 3Mg(OH)2 · MgCl2 · 8H2O, studied by in situ synchrotron X‐ray powder diffraction and thermal analyses. Attention is paid on the determination of the chemical composition and crystal structure of the lower hydrates, identified as the phases 3Mg(OH)2 · MgCl2 · 5.4H2O and 3Mg(OH)2 · MgCl2 · 4.6H2O. The crystal structure of 3Mg(OH)2 · MgCl2 · 4.6H2O is solved and refined by the Rietveld method and a structural model for the 3Mg(OH)2 · MgCl2 · 5.4H2O phase is given. These phases show statistical distribution of water molecules, hydroxide and chloride anions positioned as ligands on the magnesium octahedra. A structural scheme of the temperature induced transformations in the thermal range from 25 to 500 °C is presented. 相似文献
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Prof. Dr. Robert E. Dinnebier Ivan Halasz Daniela Freyer Jonathan C. Hanson 《无机化学与普通化学杂志》2011,637(11):1458-1462
The crystal structures of two members of the solid solution series Mg(OH)xCly x+y = 2, Mg(OH)1.7Cl0.3 (P$\tilde {3}$ m1, a = 3.169(2) Å, c = 5.530(12), V = 48.1(1) Å3 at T = 365 °C) and MgOHCl (R$\tilde {3}$ m, a = 3.3877(4) Å, c = 17.534(4) Å, V = 174.27(6) Å3 at T = 625 °C) were determined from in situ synchrotron powder diffraction data at high temperature upon dehydration of 3Mg(OH)2·MgCl2·8H2O (F3) and 5Mg(OH)2·MgCl2·8H2O (F5) phases. The crystal structures of Mg(OH)1.7Cl0.3 (example of ss‐type‐OH) and MgOHCl (example of ss‐type‐Cl) can be related to the C19 (CdCl2) and C6 (CdI2) structure type, respectively, with the disordered chloride and hydroxide anions occupying the same crystallographic site in layers. 相似文献
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The crystallization processes of hydrated Mg-borates, boric, magnesium hydroxide and Mg-oxychloride from MgO-B2O3-18%MgCl2-H2O supersaturated solution at 20°C have been studied by kinetic method. The crystallization solid phases were characterized
by X-ray powder diffraction, IR spectra, thermal analysis and chemical analysis. The liquid-solid phase diagram of thermodynamic
nonequilibrium state has been given. In this phase diagram, there exist eight crystallization fields, boric acid(H3BO3), trigomagneborite(MgO · 3B2O3 · 7.5H2O, MgO · 3B2O3 · 7H2O), hungchaoite(MgO · 2B2O3 · 9H2O), inderite(2MgO · 3B2O3 · 15H2O), chloropinnoite(2MgO · 2B2O3 · MgCl2 · 14H2O), magnesium hydroxide(Mg(OH)2) and magnesium oxychloride (5Mg(OH)2 · MgCl2 · 8H2O). 相似文献
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Kinetics of dissolution and transformation of chloropinnoite (2MgO·2B2O3· MgCl2·14H2O) in 4.5% (wt%) boric acid aqueous solution at 303 K had been studied, and the kinetic process and mechanism were investigated by the Raman spectroscopy. According to the kinetic curve, the process of dissolution and phase transformation can be divided into three stages: dissolution stage, phase transformation induction period, and crystallization stage. The experimental results showed that when chloropinnoite dissolved in boric acid aqueous solution, MgCl2 was removed and midproduct (MgB2O(OH)6·H2O) dissolved at the same time, which was different from that of in water. Kurnakovite was a final product. The experimental data of the crystallization process have been fitted with the following mathematical modification with the aid of simplex optimum method and Runge–Kutta digital solution of differential equation system: ?dc/dt = 6.31(c?0.3906)2 + 0.975(c?0.3906). Based on our experimental results and the Raman spectroscopy, kinetics and mechanism of dissolution, phase transformation, and crystallization of borate in chloropinnoite–boric acid water system are discussed. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 38: 136–143, 2006 相似文献
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Rajia Ait Benhamou Gilles Wallez Pascal Loiseau Bruno Viana Mohamed Elaatmani Mohamed Daoud Abdelwahed Zegzouti 《ChemInform》2010,41(52):no-no
RbMgPO4 is synthesized by solid state reaction of stoichiometric mixtures of Rb2CO3, 4MgCO3·Mg(OH)2·5H2O, and (NH4)2HPO4 (900 °C, 12 h). 相似文献
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Mg(BO2)2在MgCl2水溶液中的相平衡与化学平衡 总被引:1,自引:0,他引:1
借助拉曼光谱和X射线衍射(XRD)检测手段,对Mg(BO_2)_2在MgCl_2水溶液中水解的固液相平衡与物种化学平衡规律进行了研究。结果表明,MgCl_2对Mg(BO_2)_2的溶解转化、多硼氧配阴离子的物种分布有很大影响:(1)随着MgCl_2浓度从0达到饱和,Mg(BO_2)_2的表观饱和浓度从0.79%增加到1.96%,pH值从9.96降到6.27;(2)Mg(BO_2)_2在纯水中水解形成固相Mg_2B_6O_(11)·15H_2O和Mg(OH)_2,在MgCl_2溶液中形成固相Mg_2B_6O_(11)·15H_2O和Mg_3Cl_2(OH)_4·4H_2O;(3)Mg(BO_2)_2在纯水中水解,硼的物种主要为B_4O_5(OH)_4~(2-)和B_3O_3(OH)_4~-,分别占液相总硼含量的49.81%和19.54%。在MgCl_2饱和溶液中,主要为B_3O_3(OH)_4~-和B_5O_6OH)_4~-,分别占液相总硼含量的44.57%和40.00%。 相似文献
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Yutaka Sawada Junji Yamaguchi Osamu Sakurai Keizo Uematsu Nobuyasu Mizutani Masanori Kato 《Thermochimica Acta》1979,34(2):233-237
An exothermic phenomenon and a simultaneous rapid evolution of a small amount of carbon dioxide at ?500°C during thermal decomposition of hydromagnesite 4 MgCO3 · Mg(OH)2 · 4 H2O was studied by isothermal DSCTG in a carbon dioxide atmosphere. It was quantitatively confirmed that the exothermic phenomenon was due to crystallization of MgCO3 from the amorphous phase and that the evolution of carbon dioxide was due to decomposition of the MgCO3 by the heat of crystallization (?3.4 kcal mole?1. 相似文献
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Christine Rincke Horst Schmidt Wolfgang Voigt 《Acta Crystallographica. Section C, Structural Chemistry》2020,76(3):244-249
During investigations of the formation of hydrated magnesium carbonates, a sample of the previously unknown magnesium carbonate hexahydrate (MgCO3·6H2O) was synthesized in an aqueous solution at 273.15 K. The crystal structure consists of edge‐linked isolated pairs of Mg(CO3)(H2O)4 octahedra and noncoordinating water molecules, and exhibits similarities to NiCO3·5.5H2O (hellyerite). The recorded X‐ray diffraction pattern and the Raman spectra confirmed the formation of a new phase and its transformation to magnesium carbonate trihydrate (MgCO3·3H2O) at room temperature. 相似文献
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Zhiqiang Yang Sreeram Cingarapu Kenneth J. Klabunde 《Journal of Sol-Gel Science and Technology》2010,53(2):359-365
In this paper, the formation of magnesium oxychloride (Mgx(OH)yClz·nH2O) nanorods from the system MgO-MgCl2-H2O is investigated thoroughly. By systematically changing the adding amounts of the three starting materials, short nanorods
(<1 μ) or long nanorods (up to 20 μ) were obtained readily with the aspect ratio in the range of 10–70. The mechanism of the
crystal growth and the change of the crystal phase from 5Mg(OH)2·MgCl2·8H2O (phase 5) to 3Mg(OH)2·MgCl2·8H2O (phase 3) is also discussed. The products were characterized by transmission electron microscopy X-ray diffraction, energy-dispersive
X-ray spectroscopy, and thermogravimetric analysis. The resulting magnesium oxychloride nanorods were further transformed
to magnesium hydroxide (Mg(OH)2) nanorods with the shape remained by treating with NaOH at room temperature. The results shown in this paper indicate a facile
pathway to produce magnesium oxychloride or magnesium hydroxide nanorods with controllable morphology on large scale. 相似文献