CN1233546C - Preparation process of lithium aluminium hydride reduction - Google Patents
Preparation process of lithium aluminium hydride reduction Download PDFInfo
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- CN1233546C CN1233546C CN 200410028561 CN200410028561A CN1233546C CN 1233546 C CN1233546 C CN 1233546C CN 200410028561 CN200410028561 CN 200410028561 CN 200410028561 A CN200410028561 A CN 200410028561A CN 1233546 C CN1233546 C CN 1233546C
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Abstract
The invention relates to a preparation method of a metal hydride, particularly to a preparation method of aluminum lithium hydride. The present invention is characterized in that soluble aluminum salts and lithium salts are used as raw materials; precipitating agents are added into a water solution, so Al<3+> and Li<+> ions are coprecipitated; the precipitates are dried and decomposed at a high temperature to obtain oxides of the precipitates; the oxides carry out hydrogenation and reduction to obtain mixed aluminum lithium simple substances; the mixed simple substances carry out hydrogenation under the condition of the normal temperature and pressure to obtain l aluminum lithium hydride. The temperature in the preparation process of the present invention is low, and the operation is carried out at the normal pressure, so energy consumption is reduced, and the potential risk is eliminated. In addition, the present invention has the advantages of easy raw material acquisition and simple process, and provides a novel environment protection clean production process for preparing the aluminum lithium hydride.
Description
One, the technical field
The invention relates to a metal hydride, in particular to a preparation method of lithium aluminum hydride.
Second, background Art
Lithium aluminum hydride (LiAlH)4) Synthesized for the first time in 1947. It is a strong reducing agent capable of reducing organic functional groups. The most typical method for synthesizing lithium aluminum hydride is to react lithium metal with hydrogen at high temperature to produce lithium hydride (LiH), then finely grind the lithium hydride and react with aluminum trichloride in anhydrous ether in the presence of an initiator to produce lithium aluminum hydride. The large scale production is hindered by the addition of an initiator and the requirement that the lithium hydride be very fine in particle size and flammable. Later, it was proposed to produce metal complex hydrides by reacting metals with hydrogen under high pressure hydrogen, but this method has its own limitations due to a series of problems such as reaction vessels. In conclusion, the production and application of the LiAlH are limited due to the problems of high production cost, high energy consumption, safe operation and the like, so that a new LiAlH preparation method is explored4The method of (2) is an important subject.
In 1987, mr. Shen Pan text of Nankai university invented a "synthesis method of lithium aluminum hydride", applied for (patent application No. 87101196) and obtained Chinese patent, the content of which is that metal lithium reacts with hydrogen gas at normal temperature and normal pressure in the presence of solvent and catalyst to produce lithium hydride (LiH), then the lithium hydride reacts with aluminium trichloride (AlCl)3) The reaction produces lithium aluminum hydride. Although the patent avoids the process of preparing lithium hydride by high-temperature hydrogenation of metallic lithium, the obtained lithium hydride still needs to react with aluminum trichloride in an ether solution to prepare the lithium aluminum hydride. The reaction still has the problems of more byproducts, potential insecurity and the like.
Third, the invention
The invention aims to provide a preparation method of lithium aluminum hydride, which has mild reaction conditions, safety and reliability and can completely utilize raw materials.
The technical scheme provided by the invention is as follows:in the presence of Al3+、Li+Adding a precipitator into the ionic solution, and mixing and precipitating the ionic solution; then heating the mixture at high temperature to decompose the mixture to generate oxide; then the oxide is subjected to solid hydrogenation in the presence of a catalyst at a certain temperature and pressure to obtain a mixed simple substance; then the mixed simple substance is hydrogenated and reduced under the conditions of organic solvent and catalysis, and finally the product lithium aluminum hydride is obtained. The preparation method sequentially comprises the following steps:
(1) dissolving lithium salt and aluminum salt in water, adding sodium carbonate or sodium oxalate into the water solution, and allowing Li to react+、Al3+Ions in the ion exchange resinLithium carbonate, aluminum carbonate or lithium oxalate, aluminum oxalate, the reaction equation is:
in the formula: x represents an anion of a soluble aluminum salt or lithium salt;
(2) after filtering, drying the precipitate, and then treating the precipitate for 3 to 5 hours at the high temperature of 500-600 ℃ to obtain an aluminum-lithium mixed oxide;
(3) the oxide is in a catalyst CaH2In the presence of the catalyst, the reaction temperature is controlled at 150-200 ℃, and the hydrogen pressure is 15-25kg/cm2Solid hydrogenation is carried out for 3-5 hours to obtain the aluminum-lithium mixed simple substance;
(4) mixing the obtained aluminum lithium mixed simple substance in tetrahydrofuran and in a catalyst of naphthalene and TiCl4And introducing hydrogen for 4-5 hours at normal temperature and normal pressure in the presence of the catalyst to obtain the lithium aluminum hydride.
The aluminum salt is aluminum chloride, aluminum nitrate or aluminum acetate, and the lithium salt is lithium chloride, lithium nitrate or lithium acetate.
The reduction temperature in the step (3) is 180 ℃, and the hydrogen pressure is 20kg/cm2。
① the invention avoids the high temperature reaction of metal lithium and hydrogen and the high pressure reaction of metal and hydrogen, hydrogenate the lithium aluminum hydride of the lithium aluminum mixed simple substance under normal atmospheric temperature and pressure, provide one with environment friendly, accord with clean preparation method. ② from raw materials, this method regards lithium salt and aluminium salt as raw materials, but not regard lithium metal and anhydrous aluminium trichloride as raw materials, thus has reduced the production cost. ③ gets the precipitation mixture of the lithium aluminum through the coprecipitation method, reduce and get the lithium aluminum mixed simple substance through the high-temperature treatment hydrogen, the lithium aluminum mixed simple substance hydrogenates in the organic solvent under normal atmospheric temperature and pressure, get lithium aluminum hydride, its preparation method is simple. ④ this invention raw materials utilize completely, there is no by-product.A lithium aluminum hydride is prepared by lithium aluminum hydride and anhydrous aluminium, the utilization rate of the lithium trichloride is only 1/4, but the lithium hydride of 3/4 turns into cheap lithium chloride (LiCl).
Fourth, detailed description of the invention
Example 1
241.43g of aluminum chloride hexahydrate and 42.41g of lithium chloride are weighed, water is added for dissolution, a certain amount of sodium carbonate solution is added, after complete precipitation, standing and suction filtration are carried out, after solid is dried, the solid is calcined and decomposed for 4 hours at the high temperature of 500-600 ℃, oxide is obtained, the oxide is placed in a high-pressure kettle, and CaH is added2As a catalyst, at 180 ℃ and 20kg/cm2And (4) carrying out solid hydrogenation for 4-5 hours under hydrogen pressure to obtain the aluminum-lithium mixed simple substance. Adding naphthalene and TiCl as catalysts into tetrahydrofuran as an organic solvent4And introducing hydrogen gas, and hydrogenating for 4-5 hours at normal temperature and normal pressure to obtain the lithium aluminum hydride product.
Product analysis: the product is subjected to content analysis of Li, Al and H, and the analysis of Li adopts an atomic absorption method; analyzing Al by adopting an EDTA back titration volumetric method; the analysis of H adopts a drainage and gas collection method. The analysis results are shown in the following table:
example 2
241.43g of aluminum chloride hexahydrate and 42.41g of lithium chloride are weighed, water is added for dissolution, a certain amount of sodium oxalate solution is added, after complete precipitation, standing and suction filtration are carried out, and after solid is dried, the mixture is subjected to 600 ℃ treatmentCalcining at high temperature for 4 hr to obtain oxide, loading the oxide in high-pressure reactor, and adding CaH2As a catalyst, at 180 ℃ and 20kg/cm2And (4) carrying out solid hydrogenation for 4-5 hours under hydrogen pressure to obtain the aluminum-lithium mixed simple substance. Adding naphthalene and TiCl as catalysts into tetrahydrofuran as an organic solvent4And introducing hydrogen gas, and hydrogenating for 4-5 hours at normal temperature and normal pressure to obtain the lithium aluminum hydride product.
Example 3
Weighing 375g of aluminum nitrate and 69g of lithium nitrate, adding water for dissolving, adding a certain amount of sodium oxalate solution, standing and filtering after complete precipitation, calcining and decomposing the solid for 4 hours at the high temperature of 500-600 ℃ after drying to obtain an oxide, putting the oxide into a high-pressure kettle, and adding CaH2As a catalyst, at 180 ℃ and 20kg/cm2And (4) carrying out solid hydrogenation for 4-5 hours under hydrogen pressure to obtain the aluminum-lithium mixed simple substance. Adding naphthalene and TiCl as catalysts into tetrahydrofuran as an organic solvent4And introducing hydrogen gas, and hydrogenating for 4-5 hours at normal temperature and normal pressure to obtain the lithium aluminum hydride product.
Claims (3)
1. A preparation method of lithium aluminum hydride is characterized by sequentially comprising the following steps:
(1) dissolving lithium salt and aluminum salt in water, adding precipitant sodium carbonate or sodium oxalate to make Li+、Al3+The ions are precipitated in the form of lithium carbonate, aluminum carbonate or lithium oxalate, aluminum oxalate, and the reaction equation is as follows:
in the formula: x represents an anion of a soluble aluminum salt or lithium salt;
(2) after filtering, drying the precipitate, and then treating the precipitate for 3 to 5 hours at the high temperature of 500-600 ℃ to obtain an aluminum-lithium mixed oxide;
(3) the oxide is in a catalyst CaH2In the presence of the catalyst, the reaction temperature is controlled at 150-200 ℃, and the hydrogen pressure is 15-25kg/cm2Solid hydrogenation 3-5 hoursThen, the aluminum lithium mixed simple substance is obtained;
(4) mixing the obtained aluminum lithium mixed simple substance in tetrahydrofuran and in a catalyst of naphthalene and TiCl4And introducing hydrogen for 4-5 hours at normal temperature and normal pressure in the presence of the catalyst to obtain thelithium aluminum hydride.
2. The method of claim 1, wherein the aluminum salt is aluminum chloride or aluminum nitrate, and the lithium salt is lithium chloride or lithium nitrate.
3. The method for preparing lithium aluminum hydride according to claim 1 or 2, wherein the reduction temperature in the step (3) is 180 ℃ and the hydrogen pressure is 20kg/cm2。
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| Application Number | Priority Date | Filing Date | Title |
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| CN 200410028561 CN1233546C (en) | 2004-03-12 | 2004-03-12 | Preparation process of lithium aluminium hydride reduction |
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| Application Number | Priority Date | Filing Date | Title |
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| CN 200410028561 CN1233546C (en) | 2004-03-12 | 2004-03-12 | Preparation process of lithium aluminium hydride reduction |
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| CN1559883A CN1559883A (en) | 2005-01-05 |
| CN1233546C true CN1233546C (en) | 2005-12-28 |
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| CN 200410028561 Expired - Fee Related CN1233546C (en) | 2004-03-12 | 2004-03-12 | Preparation process of lithium aluminium hydride reduction |
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Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8840805B2 (en) * | 2005-09-01 | 2014-09-23 | Chemetall Gmbh | Solutions of lithium aluminum hydride |
| CN104725189A (en) * | 2014-12-09 | 2015-06-24 | 车荣睿 | Preparation method for lithium aluminum tri-tert butoxyaluminum hydride |
| CN115650264B (en) * | 2022-11-28 | 2023-03-21 | 研峰科技(北京)有限公司 | Method for efficiently recovering lithium chloride from lithium aluminum hydride preparation process |
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