CN101746726A

CN101746726A - A method for preparing pure LiNH2BH3, naNH2BH3

Info

Publication number: CN101746726A
Application number: CN200810204190A
Authority: CN
Inventors: 余学斌; 郭艳辉; 夏广林; 高梁
Original assignee: Fudan University
Current assignee: Fudan University
Priority date: 2008-12-08
Filing date: 2008-12-08
Publication date: 2010-06-23

Abstract

The invention belongs to the technical field of material preparation, in particular to a method for preparing pure LiNH2BH3, NaNH2BH3. The method comprises the following steps: in the anhydrous and oxygen-free inert atmosphere, firstly a BH3NH3 solution is synthesized; the solution and LiH, NaH continuously react to obtain solid LiNH2BH3, NaNH2BH3; after a product is washed by a solvent, the solvent is volatilized to obtain the pure LiNH2BH3, NaNH2BH3. The method has the advantages of simple process, low production cost, low requirement to equipment, easy achievement and high purity of prepared products. The prepared pure LiNH2BH3, NaNH2BH3 can meet the needs of production and research.

Description

A kind of preparation pure LiNH 2BH 3, NaNH 2BH 3Method

Technical field

The invention belongs to technical field of material, be specifically related to a kind of preparation pure LiNH ₂BH ₃, NaNH ₂BH ₃Method.

Background technology

Energy problem is the big problem that the China and the world today face jointly.Along with going deep into of development and national economy and urbanization construction, energy problem is obvious day by day to the restriction of Economic development and people's living standard raising aspect.The main body of the energy is the fossil oil of Nonrenewable resources at present, but exists it not enough in many ways as energy source: at first, this form generation economic benefit of utilizing is very low; Secondly, fossil oil is followed the pollution of various ways in the production capacity process; Moreover along with the continuous exhaustion of its reserves, it is that the application of others has brought many pressure as form of energy consumption.Hydrogen Energy possesses the energy density height, and cleanliness without any pollution is renewable, is convenient to advantages such as form of energy conversion, is the optimal carrier of the energy, becomes a research focus of exploitation aspect.In the Hydrogen Energy system, the emphasis of Chu Qing research is the novel high-capacity hydrogen storage material that exploitation can be satisfied the fuel cells applications needs, and its technical indicator is that storage hydrogen weight ratio is more than 6%.Along with the hydrogen expanding economy, many hydrogen storage materials constantly are developed, as alloy, and light metal hydride, carbon nanotube etc.Ammonia borane causes people's attention because of its stable hydrogen storage ability.But can follow a large amount of other gases when it decomposes release hydrogen, influence its practical performance, Zhitao Xiong etc. discovers with LiH or NaH and BH ₃NH ₃Behind the ball milling, its hydrogen discharging performance has obtained tangible improvement the [1.Xiangdong Kang, Zhanzhao Fang, Lingyan Kong, Huiming Cheng, etc.AmmoniaBorane Destabilized by Lithium Hydride:An Advanced On-Board Hydrogen Storage material.Advance.Material.2008,20,2756-2759.2.Zhitao Xiong, Chaw Keong Yong, Guotao Wu, etc.High-capacity hydrogen storage in lithium and sodium amidoboranes.Nature materials, 2008,17,138-141.].This product is LiNH ₂BH ₂Its initial hydrogen discharging temperature is 100 ℃, the hydrogen that can emit 8.0w.t% during to 200 ℃.But this method starting raw material BH ₃NH ₃Price is higher, and the material contact is inhomogeneous in the mechanical milling process, and temperature of reaction is wayward, causes product purity lower, and cost is higher.

Summary of the invention

The object of the invention provides the simple lower-cost preparation pure LiNH of a kind of technology ₂BH ₃, NaNH ₂BH ₃The pure LiNH that the method for compound, present method make ₂BH ₃, NaNH ₂BH ₃Can satisfy the production scientific research requirements.

Purpose of the present invention is achieved through the following technical solutions:

At first prepared in reaction goes out BH in inert atmosphere ₃NH ₃Solution, with this solution further with LiH, NaH reaction synthesizes LiNH ₂BH ₃, NaNH ₂BH ₃, behind solvent eccysis product surface attachment impurity, obtain pure LiNH except that desolvating with vacuum devolatilization method ₂BH ₃, NaNH ₂BH ₃

The inventive method at first adopts solid-liquid reaction to prepare BH ₃NH ₃Solution, with this solution and LiH, NaH continues reaction and obtains target product, and through the solvent wash removal of impurities, vacuum devolatilization method is removed to desolvate and is prepared pure LiNH ₂BH ₃, NaNH ₂BH ₃Described LiNH ₂BH ₃, NaNH ₂BH ₃Preparation and the washing in the rare gas element of anhydrous and oxygen-free, carry out, the washing solvent for use is a low boiling point solvent, as tetrahydrofuran (THF), methyltetrahydrofuran or ether material such as isopropyl ether, ether, dimethyl sulfide etc.

Above-mentioned BH ₃NH ₃Solution is by hydroborates, as NaBH ₄, LiBH ₄With the reaction of ammonium thing, further use methods such as centrifugal, sedimentation or filtration, realize obtaining after the solid-liquid separation; The concentration of described hydroborate is saturation concentration or low concentration, and temperature is at 0 ℃-80 ℃, and the reaction times is no less than 1 hour; Used ammonium thing is mainly the ammonium salt that negatively charged ion does not contain remarkable oxidisability, as NH ₄F, NH ₄Cl, (NH ₄) ₂SO ₄Deng; Related chemical reaction is: NH ₄ ⁺+ BH ₄ ^-=BH ₃NH ₃+ H ₂

Above-mentioned preparation LiNH ₂BH ₃, NaNH ₂BH ₃Raw material be LiH, NaH and the BH for preparing ₃NH ₃Solution; Related chemical reaction is respectively LiH+BH ₃NH ₃=LiNH ₂BH ₃+ H ₂NaH+BH ₃NH ₃=NaNH ₂BH ₃+ H ₂Reaction needs to guarantee BH ₃NH ₃Excessive, complete to guarantee hydride reaction; Temperature should be between 0 ℃-80 ℃ during reaction, and the reaction times is no less than 10 minutes.After preparation finishes, will with solvent solid part be washed for several times to remove the hydroborates and the BH that may contain after the product solid-liquid separation ₃NH ₃Liquid portion can be reused for BH ₃NH ₃Preparation.With the LiNH after the washing ₂BH ₃, NaNH ₂BH ₃The tightness system of packing into connects solvent removed in vacuo then.Be that the devolatilization time of desolventizing is no less than 1 hour, temperature is not higher than 80 ℃.

Solvent that above-mentioned reaction is adopted is a tetrahydrofuran (THF), methyltetrahydrofuran or ether material such as isopropyl ether, and ether, dimethyl sulfide, dimethyl thioether, methyl tertiary butyl ether, glycol dimethyl ethers etc. should guarantee before solvent uses that not moisture, oxygen reaches easily and the impurity of raw material reaction.

The prominent feature of the inventive method is embodied in:

1) BH ₃NH ₃Solution is that solution and the ammonium class substance reaction with hydroborate makes in the anhydrous inert atmosphere of drying.

2) preparation BH ₃NH ₃The reaction of solution can join ammonia salt in the solution of hydroborate, also the hydroborate drips of solution can be added on the ammonia salt, perhaps with ammonia salt with add solvent after hydroborate mixes again and promote reaction.

3) the used ammonium class of above-mentioned reaction material is mainly nonoxidizing ammonium salt.

4) above-mentioned temperature of reaction is at 0 ℃-80 ℃, and the reaction times is no less than 1 hour.

5) with the BH for preparing ₃NH ₃Solution continues and LiH, NaH prepared in reaction LiNH ₂BH ₃, NaNH ₂BH ₃, reaction keeps BH ₃NH ₃Excessively obtain purer product.

6) the washed product solvent for use comprises: tetrahydrofuran (THF), ether is etc. soluble boron hydride and BH ₃NH ₃Low boiling point solvent.

7) preparation LiNH ₂BH ₃, NaNH ₂BH ₃After reaction finishes, with solvent with solid part washing for several times after, with vacuum-drying with removal of solvents.

8) the vacuum devolatilization time should be greater than 1 hour, and temperature is not higher than 80 ℃.

It is simple that the inventive method has technology, and production cost is low, not high to equipment requirements, is easy to realize the remarkable advantage that prepared product purity is higher.

Description of drawings

Fig. 1 is a pure LiNH ₂BH ₃XRD spectra.

Fig. 2 is a pure LiNH ₂BH ₃The thermogravimetric spectrogram.

Fig. 3 is pure NaNH ₂BH ₃XRD spectra.

Embodiment

Embodiment 1 preparation LiNH ₂BH ₃

Under 25 ℃ of the room temperatures, with 0.9g LiBH ₄Be dissolved in argon gas in the 100ml tetrahydrofuran (THF), dissolving fully.NH with 2.0g ₄F adds this solution B H ₃NH ₃React, react after 10 hours, the reactant centrifugation, get supernatant liquid and join among the 0.3g LiH, behind the reaction 30min, solution centrifugal is separated, with the tetrahydrofuran (THF) of 50mL with solids wash three times after, the gained solid product was obtained final product in 3 hours 50 ℃ of vacuum-dryings.Fig. 1 is the XRD spectra of products therefrom; Fig. 2 is the hot weightless picture of product.

Embodiment 2 preparation NaNH ₂BH ₃

Under 25 ℃ of the room temperatures, with 1.0g NaBH ₄Be dissolved in argon gas in the 50ml tetrahydrofuran (THF), dissolving fully.NH with 1.2g ₄F adds this solution B H ₃NH ₃React, react after 10 hours, the reactant centrifugation, get supernatant liquid and join among the 0.5g NaH, behind the reaction 30min, solution centrifugal is separated, with the tetrahydrofuran (THF) of 50mL with solids wash three times after, the gained solid product was obtained final product in 3 hours 50 ℃ of vacuum-dryings.Fig. 3 is the XRD spectra of products therefrom.

Claims

1. one kind prepares pure LiNH ₂BH ₃, NaNH ₂BH ₃Method, it is characterized in that, at first prepare BH with solid-liquid reaction ₃NH ₃Solution, with this solution and LiH, NaH continues reaction and obtains target product, and through the solvent wash removal of impurities, vacuum devolatilization method is removed and is desolvated, and makes pure LiNH ₂BH ₃, NaNH ₂BH ₃Related chemical reaction is respectively LiH+BH ₃NH ₃=LiNH ₂BH ₃+ H ₂NaH+BH ₃NH ₃=NaNH ₂BH ₃+ H ₂

2. method according to claim 1 is characterized in that, described BH ₃NH ₃Solution is by the reaction of hydroborates and ammonium thing, further uses centrifugally, and sedimentation or filter method are realized making after the solid-liquid separation; Described chemical reaction is: NH ₄ ⁺+ BH ₄ ^-=BH ₃NH ₃+ H ₂

3. method according to claim 2 is characterized in that described hydroborates is selected from NaBH ₄Or LiBH ₄

4. method according to claim 1 is characterized in that described reaction solvent is a tetrahydrofuran (THF), methyltetrahydrofuran or ether material, and described solvent is not moisture before using, oxygen reaches easily and the impurity of raw material reaction.

5. method according to claim 4 is characterized in that described ether material is selected from isopropyl ether, ether, dimethyl sulfide, dimethyl thioether, methyl tertiary butyl ether or glycol dimethyl ether.

6. method according to claim 2 is characterized in that described ammonium thing is the ammonium salt that negatively charged ion does not contain remarkable oxidisability.

7. method according to claim 6 is characterized in that described ammonium thing is selected from NH ₄F, NH ₄Cl or (NH ₄) ₂SO ₄

8. according to the described method of claim 2, the concentration that it is characterized in that described hydroborates is saturation concentration or low concentration, and temperature of reaction is 0 ℃-80 ℃, and the reaction times is no less than 1 hour.

9. method according to claim 1 is characterized in that LiNH ₂BH ₃, NaNH ₂BH ₃Preparation and washing are to carry out in the rare gas element of anhydrous and oxygen-free, and the washing solvent for use is a low boiling point solvent.

10. method according to claim 9 is characterized in that described low boiling point solvent is selected from tetrahydrofuran (THF), methyltetrahydrofuran or isopropyl ether, ether or dimethyl sulfide.

11. method according to claim 1 is characterized in that described reaction needs BH ₃NH ₃Excessive.

12., it is characterized in that preparing LiNH according to the described method of claim 1 ₂BH ₃, NaNH ₂BH ₃Shi Wendu is between 0 ℃-80 ℃, and the reaction times is no less than 10 minutes.

13. according to the described method of claim 1, it is characterized in that the described devolatilization time of desolventizing is no less than 1 hour, temperature is not higher than 80 ℃.