Method for preparing high-purity strontium undecahydrotetraborate through ion exchange

Abstract

The invention provides a method for preparing high-purity strontium undecahydrotetradecaborate through ion exchange. The method comprises the following steps: firstly, dissolving and filtering a sodium undecahydrotetradecaborate crude product to obtain a sodium undecahydrotetradecaborate crude product solution; then adsorbing and desorbing the crude solution of the undecahydrotetradecaboron sodium salt on anion exchange resin to obtain a pure water solution of undecahydrotetradecaboronic acid; and finally, dropwise adding the strontium hydroxide aqueous solution into the undecahydrotetradecaboronic acid aqueous solution to prepare the strontium undecahydrotetradecaboronic acid salt. The product obtained by the preparation method has the characteristics of high purity, simple process flow, economy, environmental protection and suitability for industrial production, and the comprehensive yield can reach 98.4 wt.%. According to the preparation method disclosed by the invention, the anionic ion exchange resin is used for removing impurities, and then purification is performed through neutralization and crystallization, so that the method is convenient to operate, the purification quantitative control is convenient, and the boron undecahydromyristate can be purified from a superior pure reagent to a high purity of 99.8 wt.% or above.

Description

Technical Field

[0001] The invention belongs to the technical field of solid propellants and relates to borates, and in particular to a method for preparing high-purity strontium undecylhydrogen tetradecanoate salt by ion exchange. Background Art

[0002] Undecahydrotetradecanoate has important application value in the field of solid missile propellants as an intermediate in the preparation of decaborane and a propellant burning rate regulating component. However, the high cost caused by the difficulty in purification seriously restricts its application scale. With the development of the propellant industry, its low-cost purification method has important prospects.

[0003] In the prior art, the purification method of undecahydrotetradecanoic acid salt is mainly recrystallization. When a substance solidifies from a liquid part to a solid state, due to the different solubility of impurities in its liquid and solid states, the impurity concentration in the solid state is often lower than the impurity concentration in the liquid state. This phenomenon is called fractionation. The substance can be purified by using this phenomenon. However, since the solubility of undecahydrotetradecanoic acid salt is not large and the dissolution curve is not steep enough, the efficiency of the recrystallization method is very low, the purification effect is not ideal, and the single purification efficiency is not high. Multiple recrystallizations are required to achieve the required purity. In this way, the yield after purification will be greatly reduced, and a large amount of crystallization liquid will also be increased. Summary of the invention

[0004] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a method for preparing high-purity strontium undecahydrotetradecaborate by ion exchange, so as to solve the technical problem that the preparation method in the prior art is difficult to balance the purification efficiency and yield.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions to achieve the above problems:

[0006] A method for preparing high-purity strontium undecahydrotetradecaborate by ion exchange, wherein the method comprises the following steps: firstly dissolving and filtering a crude sodium undecahydrotetradecaborate to obtain a crude sodium undecahydrotetradecaborate solution; then adsorbing and analyzing the crude sodium undecahydrotetradecaborate solution on an anion exchange resin to obtain a pure aqueous solution of undecahydrotetradecaboric acid; and finally dripping a strontium hydroxide aqueous solution into the aqueous solution of undecahydrotetradecaboric acid to obtain the strontium undecahydrotetradecaborate.

[0007] The present invention also has the following technical features:

[0008] Specifically, the method comprises the following steps:

[0009] Step 1, dissolving the crude product:

[0010] The crude sodium salt of undecahydrogen tetradecaboron is mixed and dissolved with water.

[0011] Step 2: Filter:

[0012] After dissolution, the insoluble matter is filtered with neutral filter paper to obtain a crude solution of sodium undecahydrogen tetradecaborate.

[0013] Step 3, ion exchange adsorption:

[0014] The crude solution of sodium 14-dodecyl borate is passed through an anion exchange resin, and the anions B in the crude solution of sodium 14-dodecyl borate are 11 H 14 - Adsorb onto anion exchange resin, and wash the saturated anion exchange resin with deionized water.

[0015] Step 4, ion exchange analysis:

[0016] Sulfuric acid solution was used as the analytical agent for elution and analysis. The anion B adsorbed by the anion exchange resin 11 H 14 - The anion exchange resin is eluted into the solution and then washed with deionized water to obtain a pure aqueous solution of undecahydrotetradecaboric acid. The anion exchange resin is recovered for standby use.

[0017] Step 5: Crystallization and drying:

[0018] Add strontium hydroxide aqueous solution dropwise to the pure undecahydrotetradecaboric acid aqueous solution obtained in step 4 until the solution becomes neutral to precipitate strontium undecahydrotetradecaborate salt product, filter and dry to obtain strontium undecahydrotetradecaborate salt.

[0019] Preferably, in step 1, the purity of the crude sodium undecahydrotetradecanoate is 99.8wt.%.

[0020] Preferably, in step three, the anion exchange resin is an acrylic acid-based strongly basic anion exchange resin D213.

[0021] Specifically, the purity of the strontium undecahydrotetradecoborate salt is greater than or equal to 99.5wt.%.

[0022] Preferably, in step 1, the crude sodium salt of undecahydrogen tetradecaboron and deionized water are mixed and dissolved in a mass ratio of 1:(15-20).

[0023] Further preferably, in step 1, the crude sodium salt of undecahydrogen tetradecaboron and deionized water are mixed and dissolved in a mass ratio of 1:20.

[0024] Preferably, in step 3, the crude solution of sodium undecahydrogen tetradecaborate is passed through an anion exchange resin at a rate of 5 to 10 L / h.

[0025] Further preferably, in step 3, the crude solution of sodium undecahydrogen tetradecaborate is passed through an anion exchange resin at a rate of 5 L / h.

[0026] Preferably, in step 4, elution and analysis are performed at a flow rate of 5 to 10 L / h.

[0027] Further preferably, in step 4, elution and analysis are performed at a flow rate of 5 L / h.

[0028] Compared with the prior art, the present invention has the following technical effects:

[0029] (I) The product obtained by the preparation method of the present invention has high purity, simple process flow, economy, environmental protection, and is suitable for industrial production. The comprehensive yield can reach 98.4wt.%.

[0030] (II) The preparation method of the present invention uses an anionic ion exchange resin to remove impurities, and then purifies by neutralization and crystallization. The method is easy to operate and convenient to control the quantitative purification. Undecanoic acid tetradecanoate can be purified from a high-purity reagent to a high purity of 99.8wt.%. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is the NMR boron spectrum of strontium undecahydrotetradecaborate.

[0032] The specific contents of the present invention are further explained in detail below in conjunction with embodiments. DETAILED DESCRIPTION

[0033] It should be noted that, unless otherwise specified, all materials and equipment in the present invention are those known in the art.

[0034] In the present invention, the purity of the crude sodium undecahydrotetradecoborate is 95.0wt.%; the anion exchange resin is the known acrylic acid-based strongly basic anion exchange resin D213.

[0035] The strontium undecahydrotetradecaborate of the invention is used as an intermediate for preparing decaborane.

[0036] The strontium undecahydrotetradecaborate salt of the invention is used as a propellant burning rate regulating component.

[0037] Specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent changes made on the basis of the technical solution of this application fall within the protection scope of the present invention.

[0038] Example:

[0039] This embodiment provides a method for preparing high-purity strontium undecylhydride tetradecanoate by ion exchange, and the method is carried out according to the following steps:

[0040] Step 1, dissolving the crude product:

[0041] 500 g of crude sodium undecanehydrogen tetradecaborate salt and deionized water were mixed and dissolved in a mass ratio of 1:20.

[0042] Step 2: Filter:

[0043] After dissolution, the insoluble matter was filtered out with neutral filter paper to obtain 50 L of a clear crude solution of sodium undecahydrogen tetradecaborate.

[0044] Step 3, ion exchange adsorption:

[0045] The filtered solution was passed through an anion exchange resin with a loading capacity of 30 kg at a rate of 5 L / h. 11 H 14 - Adsorbed onto anion exchange resin, the saturated anion exchange resin is washed with deionized water while removing impurities that are not adsorbed.

[0046] Step 4, ion exchange analysis:

[0047] The concentration of 1M sulfuric acid solution was eluted and analyzed at a flow rate of 5L / h, and the total elution volume was 10L. The anion B adsorbed by the anion exchange resin 11 H 14 - The anion exchange resin was eluted into the solution and then washed with 10 L of deionized water to obtain a pure aqueous solution of undecahydrotetradecaboric acid. The anion exchange resin was recovered for standby use.

[0048] Step 5: Crystallization and drying:

[0049] A strontium hydroxide (1M) aqueous solution was added dropwise to a pure aqueous solution of undecahydrotetradecaboric acid until the solution became neutral to precipitate a finished product of strontium undecahydrotetradecaborate salt. After filtering, the product was dried in an oven to obtain 659.9 g of pure strontium undecahydrotetradecaborate salt with a purity of 99.8 wt.%, and a yield of 98.4 wt.%.

[0050] The characterization data of the product obtained by the present invention are as follows Figure 1 As shown, from Figure 1 It can be seen that the product obtained in this example is the target compound strontium undecylhydride tetradecanoate.

Claims

1. A method for preparing high-purity strontium undecylhydride tetradecanoate by ion exchange, characterized in that: The method comprises the following steps: firstly dissolving and filtering a crude sodium salt of undecahydrotetradecaborate to obtain a crude sodium salt solution of undecahydrotetradecaborate; then adsorbing and analyzing the crude sodium salt solution of undecahydrotetradecaborate on an anion exchange resin to obtain a pure aqueous solution of undecahydrotetradecaboric acid; and finally dripping a strontium hydroxide aqueous solution into the aqueous solution of undecahydrotetradecaboric acid to obtain strontium salt of undecahydrotetradecaborate.

2. The method for preparing high-purity strontium undecahydrotetradecaborate by ion exchange as described in claim 1, characterized in that: The method comprises the following steps: Step 1, dissolving the crude product: Mix and dissolve the crude sodium salt of undecahydrogen tetradecaboron and water; Step 2: Filter: After dissolution, the insoluble matter is filtered out with neutral filter paper to obtain a crude solution of sodium 10-decahydrogen tetradecaborate; Step 3, ion exchange adsorption: The crude solution of sodium 14-dodecyl borate is passed through an anion exchange resin, and the anions B in the crude solution of sodium 14-dodecyl borate are 11 H 14 - Adsorbed onto anion exchange resin, and the saturated anion exchange resin was washed with deionized water; Step 4, ion exchange analysis: Sulfuric acid solution was used as the analytical agent for elution and analysis. The anion B adsorbed by the anion exchange resin 11 H 14 - The anion exchange resin is then washed with deionized water to obtain a pure aqueous solution of undecahydrotetradecaboric acid, and the anion exchange resin is recovered for standby use; Step 5: Crystallization and drying: Add strontium hydroxide aqueous solution dropwise to the pure undecahydrotetradecaboric acid aqueous solution obtained in step 4 until the solution becomes neutral to precipitate strontium undecahydrotetradecaborate salt product, filter and dry to obtain strontium undecahydrotetradecaborate salt.

3. The method for preparing high-purity strontium undecahydrotetradecaborate by ion exchange as described in claim 2, characterized in that: In step 1, the purity of the crude sodium undecahydrotetradecanoate is 95.0wt.%.

4. The method for preparing high-purity strontium undecahydrotetradecaborate by ion exchange as described in claim 2, characterized in that: In step 3, the anion exchange resin is an acrylic acid-based strongly basic anion exchange resin D213.

5. The method for preparing high-purity strontium undecahydrotetradecaborate by ion exchange as described in claim 2, characterized in that: The purity of the strontium undecylene tetradecaborate salt is 99.8 wt.%.

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