Preparation And Crystal Structure Analysis Of Na-ε-K-Al₁₃ And Al₈ Sulfates And Drawing Of 200℃ And 150℃ Hydrothermal Phase Diagrams Of AlCl₃-Al₂O₃-H_2O System

The aluminum element in the environment is closely related to human production activities.If it is not possible to study and explain the hydrolysis mechanism of the positive trivalent aluminum ion in the aqueous solution and the conversion rule of the polymerization form in the aqueous solution,it will not only limit environmental chemistry,etc.The development of many chemical fields will also affect the development of various fields in human production activities.However,due to the relatively difficult cultivation of polyaluminum single crystals and many restricted conditions.So far many exact structures have not been obtained,also the mechanism of its hydrolysis have not figured out.Therefore,it is necessary to use appropriate control means to separate the complex and changeable aluminum salt hydrolysis solution sequentially or add appropriate trapping agents to separate out various polyaluminum compounds and study their structures.This paper studied and used three hydrothermal and atmospheric phase diagrams of the ternary and quaternary systems at 100℃～200℃.Under the guidance of the phase diagram,combine salt capture and direct separation to obtain[Na（H₂O）₄Al₁₃O₄（OH）₂₄（H₂O）₁₂]（SO₄）₄?10H₂O,[Al₈（OH）₁₄（H₂O）₁₈]（SO₄）₅?15H₂O,Al₅Cl₃（OH）₁₂?7H₂O,Al₁₁（OH）₃₀Cl₃,Al OOH,Na[Al₃（OH）)₆（SO₄）₂]and Na Al（SO₄）₂?6H₂O etc.The first two compounds were analyzed by single crystal X-ray diffraction,and it was found that the first compound had two absolute structures that were mirror images of each other,the correctness of the obtained structure was verified by a variety of characterization methods.In this paper,Na OH was used to force hydrolyze Al Cl₃ solution to prepare a stock solution with an alkalinity of 2.4.Four different capture agents,Li₂SO₄,Na₂SO₄,K₂SO₄,and Cs₂SO₄,were added to produce tetrahedral single crystals.The results of structural analysis showed that their compositions were uniform.Is[Na（H₂O）₄Al₁₃O₄（OH）₂₄（H₂O）₁₂]（SO₄）₄?10H₂O,The polycation is the infinitely extending Na─ε-K─Al₁₃([Na（H₂O）₄Al₁₃O₄（OH）₂₄（H₂O）₁₂]⁸⁺)instead of the isolatedε-K─Al₁₃([Al₁₃O₄（OH）₂₄（H₂O）₁₂]⁷⁺),Eachε-K─Al₁₃ is connected to four Na（H₂O）₄⁺,and each Na（H₂O）₄⁺is also connected to fourε-K─Al₁₃,The two develop infinitely in three-dimensional space at a ratio of 1:1 to form a three-dimensional frame structure,With the different spatial orientation of Na─ε-K─Al₁₃ in the unit cell,the position distribution of SO₄^2-and interstitial water in the unit cell is also different,two absolute structures of A and B are mirror images of each other.The structure of 32 crystals captured by four capture agents was randomly analyzed by X-ray single crystal diffraction method,the statistical results of the two absolute structures proved that no matter what kind of capture agent was used,the obtained product contains two absolute structures,A and B,and the proportions were both 50%,It showed that the two absolute structures had the same probability of precipitation under the same crystallization conditions.The qualitative analysis results of XRF and XPS elements showed that although Li⁺,K⁺and Cs⁺ions failed to enter the crystal lattice and undergo isomorphous replacement,However,the results of single crystal structure analysis found that the presence of Cs⁺ions in the crystallization environment had an inhibitory effect on the disordering of the four coordinated water molecules in Na（H₂O）₄⁺.The results of density measurement,thermogravimetric analysis,XRD,infrared spectroscopy,and solution XRF quantitative analysis all supported the structural formula of the compound as[Na（H₂O）₄Al₁₃O₄（OH）₂₄（H₂O）₁₂]（SO₄）₄?10H₂O,It was completely consistent with the single crystal analysis results.Using 100℃atmospheric phase diagram of the Al₂（SO₄）₃-Al（OH）₃-H₂O system as a guide,we successfully obtained a single crystal of[Al₈（OH）₁₄（H₂O）₁₈]（SO₄）₅?15H₂O by means of spontaneous hydrolysis.Among them,the structure of polycation Al₈([Al₈（OH）₁₄（H₂O）₁₈]¹⁰⁺)is formed by connecting of four Al O₆ octahedrons along the outer edge of a flat plate formed by common edge connection of four Al O₆ octahedrons,Same structure as reported in literature.EDS elemental analysis and XRD phase analysis results were consistent with the single crystal structure analysis results.Our research group has obtained persulfuric acid chlorination Al₈ and naphthalene disulfonic acid chlorination Al₈ by introducing sulfate or naphthalene disulfonate into the spontaneously hydrolyzed polyaluminum chloride solution.Moreover,Al₈ sulfate was directly precipitated in the spontaneously hydrolyzed polyaluminum sulfate solution.It proved the universality of this polyaluminum form in the spontaneously hydrolyzed polyaluminum solution once again.This provided evidence for communicating the relationship between the forms of polyaluminum to find the law of mutual transformation and evolution.Using the preparative high-temperature and high-pressure reactor with the properties of online filtering and sampling,online distillation and compression,and online midway feeding,we successfully drawn two isothermal water thermal phase diagrams of the Al Cl₃-Al₂O₃-H₂O system at 150℃and 200℃.It is found that there are only three single-phase crystal regions of Al OOH,Al₅Cl₃（OH）₁₂?7H₂O and Al Cl₃?6H₂O at 150℃0.4MPa;There are only three single-phase crystallization regions of Al OOH,Al₁₁（OH）₃₀Cl₃ and Al Cl₃?6H₂O at 200℃and 0.6MPa.It successfully synthesized Al₅Cl₃（OH）₁₂?7H₂O and Al₁₁（OH）₃₀Cl₃ two pure polyaluminum compounds with good crystallinity under the guidance of the drawn phase diagram,Conditions are prepared for further precise control of the growth of single crystals and analysis of its structure or analysis of its structure through powder X-ray diffraction and electron diffraction data.It also laid a solid foundation for drawing the tetrahedral phase diagrams of the Na Cl-Al Cl₃-Al₂O₃-H₂O and Al₂（SO₄）₃-Al Cl₃-Al₂O₃-H₂O systems and the Al Cl₃-Al₂O₃-H₂O system triangular prism phase diagrams.In order to improve the efficiency and accuracy of the analysis and test in the process of drawing the phase diagram,and to prevent the escape of chlorine in the sample during the acid dissolution process.In this paper,a new quantitative analysis method for the determination of the element content of the sample by the KOH solution dissolved in the XRF solution method is established,The rapid and accurate analysis of Al,Na,Cl,S and other elements is realized,and the efficiency of drawing the phase diagram is greatly improved.This paper has also successfully drawn the Al₂（SO₄）₃-Na₂SO₄-Al（OH）₃-H₂O system at 100℃atmospheric pressure tetrahedral phase diagram of the Al₂（SO₄）₃-Na₂SO₄-H₂O surface triangle phase diagram and part of the quaternary volume phase region,we found that there was only a single-phase crystalline region of Na Al（SO₄）₂?6H₂O a double salt on the triangular phase diagram,and there was a single-phase crystalline region of Na[Al₃（OH）₆（SO₄）₂]in the bulk region.Drawing of the four-component tetrahedral phase diagram,gradually realized that the method for preparing polyaluminum compounds by adding the capture agent to the three-component system could be designed as a four-component system with a tetrahedral phase diagram to control,It is expected to synthesize more new polyaluminum compounds and obtain the structure of the polyaluminum form among them,providing more evidence for the establishment of a complete mechanism of the formation and evolution of polyaluminum form.