CN105366642B - A kind of rare earth synthesizes AlH3Method - Google Patents

Abstract

_A method for synthesizing AlH3 in a low _- heat solid state, which relates to a method for synthesizing AlH3. _The present invention _aims to solve the problem that AlCl3 and LiAlH4 are reacted in a solvent to synthesize AlH3, and the product generated is the ether complex _of AlH3 instead _of AlH3 and the problem _of wasting solvent. The method of the present invention is as follows: a mixture of LiAlH ₄ , LiBH ₄ and AlCl ₃ with a molar ratio of (4-10): 1:1 is used in the glove box, and the temperature is gradually raised to 65-80°C during the grinding process, and the temperature is maintained Continue grinding for 1-3 hours; the reacted samples were washed with ether and tetrahydrofuran respectively, and dried in a vacuum oven at 50°C for 2 hours to obtain the target product. The invention has the advantages of simple process, low equipment requirement and cheap raw material price, which provides a good basis for the subsequent preparation of solid-phase AlH3 _; the product prepared by the invention can be used as a reducing agent.

Description

A kind of method of low-heat solid phase synthesis AlH3

technical field

The invention relates to a method for preparing non-solvated AlH ₃ , in particular to a method for preparing AlH ₃ by directly grinding AlCl ₃ , LiBH ₄ and LiAlH ₄ at low temperature.

Background technique

Energy is an important driving force for a country's industrial growth and economic development. Although the energy used now is still dominated by traditional energy sources such as oil, coal, and natural gas, and this basic energy structure will not change in a short time. However, our current traditional energy situation is already very severe, so the trend of developing and utilizing clean and low-carbon new energy is gradually obvious.

There are many types of new clean energy, including wind energy, solar energy, tidal energy, hydrogen energy and so on. Among these new clean energy sources, hydrogen energy has the following advantages: (1) The use of hydrogen energy does not produce any pollution at all, because its final product is only water. (2) Hydrogen energy has good combustion performance and good chemical activity. (3) Hydrogen energy has a higher energy ratio. (4) The hydrogen storage capacity on the earth is very high, and many substances can produce hydrogen. (5) Can be used repeatedly. Although hydrogen energy has bright prospects and great potential application value, the storage of hydrogen is the key technology for the widespread application of hydrogen energy, and it is also the bottleneck of hydrogen energy utilization at present.

Aluminum hydride (AlH ₃ ) contains 10.1% hydrogen by mass fraction, and releases hydrogen gas at about 100°C. Despite its irreversible and unstable properties, its high hydrogen storage capacity and low decomposition temperature make it a promising hydrogen storage material and has been extensively studied in recent years.

In 1951 Sinke et al. ^[31] implemented adjustments based on Finholt's method. They used AlCl ₃ and LiAlH ₄ as raw materials and Et ₂ O as the reaction medium to successfully obtain AlH ₃ . The specific process of the reaction can be expressed as 1-3:

3LiAlH ⁴ +AlCl ³ →4AlH ₃ +3LiCl (1-3)

The LiCl in it is precipitated, so we can easily obtain AlH ₃ through filtration and separation. The advantage of this reaction is that the target product is directly generated, but what they get is still AlH ₃ combined with ether. This method needs a large amount of organic reagents such as ether, benzene, toluene in the process _of synthesizing AlH3, and removes ether process complex.

Contents of the invention

The purpose of the present invention is to solve the problem that AlCl ₃ and LiAlH ₄ react in a solvent to synthesize AlH ₃ and the product is the ether of AlH ₃ instead of AlH ₃ and waste solvent, and to provide a low-heat solid-phase synthesis of AlH ₃ Methods.

The purpose of the present invention is achieved through the following technical solutions:

Use a mixture of LiAlH ₄ , LiBH ₄ and AlCl ₃ with a molar ratio of (4-10):1:1 in the glove box, gradually raise the temperature to 65-80°C during the grinding process, and keep grinding at this temperature for 1-3 hours; The reacted samples were washed with ether and tetrahydrofuran respectively, and the product obtained by drying in a vacuum oven at 50°C for 2 hours was the target product. The specific preparation steps were as follows:

1. Weigh LiAlH ₄ , LiBH ₄ and AlCl ₃ in a glove box with a molar ratio of (4-10):1:1 and mix them to obtain a mixture;

2. Grind the mixture of step 1 in an agate mortar and grind it in a sand bath, and raise the temperature to 65-80°C at a heating rate of 1°C/min;

3. Keep the temperature at 65-80°C and continue grinding for 1-3 hours;

4. The substance obtained after grinding in step 3 was washed once with ether and tetrahydrofuran respectively, then placed in a vacuum drying oven, and dried at 50° C. for 2 hours to obtain AlH ₃ .

The present invention comprises following beneficial effect:

1. The process of the present invention is simple, the requirements for equipment are low, and the price of raw materials is cheap, which provides a good foundation for the preparation of solid _- phase AlH in the future;

2. The product prepared by the present invention can be used as a reducing agent, and has good utilization value in organic and inorganic synthesis;

_3. The product of the present invention is not the ether and compound of AlH, which saves a large amount of solvent.

Description of drawings

Fig. ₁ is the XRD figure of the AlH3 of the obtained product through and without diethyl ether and tetrahydrofuran washing.

detailed description

Specific embodiment one: a kind of low-heat solid phase synthesis AlH _of the present embodiment The method, described method is carried out under anhydrous and oxygen-free conditions, and concrete steps are as follows:

1. Weigh LiAlH ₄ , LiBH ₄ and AlCl ₃ in a glove box with a molar ratio of (4-10):1:1 and mix them to obtain a mixture;

2. Grind the mixture of step 1 in an agate mortar and grind it in a sand bath, and raise the temperature to 65-80°C at a heating rate of 1°C/min;

3. Keep the temperature at 65-80°C and continue grinding for 1-3 hours;

4. The substance obtained after grinding in step 3 was washed once with ether and tetrahydrofuran respectively, then placed in a vacuum drying oven, and dried at 50° C. for 2 hours to obtain AlH ₃ .

Embodiment 2: This embodiment is different from Embodiment 1 in that the molar ratio of LiAlH ₄ , LiBH ₄ , and AlCl ₃ is (4-9):1:1. Others are the same as in the first embodiment.

Embodiment 3: The difference between this embodiment and Embodiment 1 is that the molar ratio of LiAlH ₄ , LiBH ₄ and AlCl ₃ is (4-8):1:1. Others are the same as in the first embodiment.

Embodiment 4: This embodiment is different from Embodiment 1 in that the molar ratio of LiAlH ₄ , LiBH ₄ , and AlCl ₃ is (4-7):1:1. Others are the same as in the first embodiment.

Embodiment 5: This embodiment is different from Embodiment 1 in that the molar ratio of LiAlH ₄ , LiBH ₄ and AlCl ₃ is (4-6):1:1. Others are the same as in the first embodiment.

Embodiment 6: This embodiment is different from Embodiment 1 in that the molar ratio of LiAlH ₄ , LiBH ₄ and AlCl ₃ is 5:1:1. Others are the same as in the first embodiment.

Embodiment 7: This embodiment is different from Embodiment 1 in that: the heating and heat preservation method is a sand bath. Others are the same as in the first embodiment.

Embodiment 8: The difference between this embodiment and Embodiment 1 is that the temperature in Step 2 and Step 3 is 65-75°C. Others are the same as in the first embodiment.

Embodiment 9: This embodiment is different from Embodiment 1 in that: the temperature in Step 2 and Step 3 is 65-70°C. Others are the same as in the first embodiment.

Embodiment 10: This embodiment is different from Embodiment 1 in that the temperature in Step 2 and Step 3 is 68°C. Others are the same as in the first embodiment.

The content of the present invention is not limited to the content of the above-mentioned embodiments, and a combination of one or several specific embodiments can also achieve the purpose of the invention.

Verify the beneficial effects of the present invention through the following examples:

Example 1

A kind of low-heat solid-phase synthesis AlH _of the present embodiment method, described method is carried out under anhydrous and oxygen-free conditions, and concrete steps are as follows:

1. Weigh and mix LiAlH ₄ , LiBH ₄ and AlCl ₃ with a molar ratio of 5:1:1 in a glove box to obtain a mixture;

2. Grind the mixture of step 1 in an agate mortar and grind it in a sand bath, and raise the temperature to 72°C at a heating rate of 1°C/min;

3. Keep the temperature at 72°C and continue grinding for 3 hours;

4. The substance obtained after grinding in step 3 was washed once with ether and tetrahydrofuran respectively, then placed in a vacuum drying oven, and dried at 50° C. for 2 hours to obtain AlH ₃ .

_The XRD patterns of the AlH prepared in this example and the XRD patterns of the products washed with or without ether and tetrahydrofuran can be seen from Figure 1, wherein the two at the bottom of the figure are the calibration curves of two AlH ₃ and are not products. There is a characteristic peak of α-AlH ₃ in the directly ground product, but no characteristic peak of γ-AlH ₃ , and there is γ-AlH ₃ in the product after washing, but there is no α-AlH ₃ , indicating that γ-AlH ₃ The content of α-AlH 3 is too low, and α-AlH ₃ dissolves in ether during the washing process.

Example 2

A kind of low-heat solid-phase synthesis AlH _of the present embodiment method, described method is carried out under anhydrous and oxygen-free conditions, and concrete steps are as follows:

1. Weigh and mix LiAlH ₄ , LiBH ₄ and AlCl ₃ with a molar ratio of 6:1:1 in a glove box to obtain a mixture;

2. Grind the mixture of step 1 in an agate mortar and grind it in a sand bath, and raise the temperature to 72°C at a heating rate of 1°C/min;

3. Keep the temperature at 72°C and continue grinding for 3 hours;

4. The substance obtained after grinding in step 3 was washed once with ether and tetrahydrofuran respectively, then placed in a vacuum drying oven, and dried at 50° C. for 2 hours to obtain AlH ₃ .

In this example, there is a characteristic peak of α-AlH ₃ in the directly ground product, but no characteristic peak of γ-AlH ₃ , and there is γ-AlH 3 in the product after washing, but α-AlH ₃ does not exist, indicating that γ-AlH ₃ does not exist before washing. The content of _-AlH3 is too low, and α _- AlH3 dissolves in ether during washing.

Example 3

A kind of low-heat solid-phase synthesis AlH _of the present embodiment method, described method is carried out under anhydrous and oxygen-free conditions, and concrete steps are as follows:

1. Weigh and mix LiAlH ₄ , LiBH ₄ and AlCl ₃ with a molar ratio of 8:1:1 in the glove box to obtain the mixture;

2. Grind the mixture of step 1 in an agate mortar and grind it in a sand bath, and raise the temperature to 70°C at a heating rate of 1°C/min;

3. Keep the temperature at 70°C and continue grinding for 3 hours;

4. The substance obtained after grinding in step 3 was washed once with ether and tetrahydrofuran respectively, then placed in a vacuum drying oven, and dried at 50° C. for 2 hours to obtain AlH ₃ .

Example 4

A kind of low-heat solid-phase synthesis AlH _of the present embodiment method, described method is carried out under anhydrous and oxygen-free conditions, and concrete steps are as follows:

1. Weigh and mix LiAlH ₄ , LiBH ₄ and AlCl ₃ with a molar ratio of 8:1:1 in the glove box to obtain the mixture;

2. Grind the mixture of step 1 in an agate mortar and grind it in a sand bath, and raise the temperature to 72°C at a heating rate of 1°C/min;

3. Keep the temperature at 72°C and continue grinding for 3 hours;

4. The substance obtained after grinding in step 3 was washed once with ether and tetrahydrofuran respectively, then placed in a vacuum drying oven, and dried at 50° C. for 2 hours to obtain AlH ₃ .

Example 5

A kind of low-heat solid-phase synthesis AlH _of the present embodiment method, described method is carried out under anhydrous and oxygen-free conditions, and concrete steps are as follows:

1. Weigh and mix LiAlH ₄ , LiBH ₄ and AlCl ₃ with a molar ratio of 7:1:1 in a glove box to obtain a mixture;

2. Grind the mixture of step 1 in an agate mortar and grind it in a sand bath, and raise the temperature to 72°C at a heating rate of 1°C/min;

3. Keep the temperature at 72°C and continue grinding for 3 hours;

4. The substance obtained after grinding in step 3 was washed once with ether and tetrahydrofuran respectively, then placed in a vacuum drying oven, and dried at 50° C. for 2 hours to obtain AlH ₃ .

Example 6

A kind of low-heat solid-phase synthesis AlH _of the present embodiment method, described method is carried out under anhydrous and oxygen-free conditions, and concrete steps are as follows:

1. Weigh and mix LiAlH ₄ , LiBH ₄ and AlCl ₃ with a molar ratio of 4:1:1 in the glove box to obtain the mixture;

2. Grind the mixture of step 1 in an agate mortar and grind it in a sand bath, and raise the temperature to 72°C at a heating rate of 1°C/min;

3. Keep the temperature at 72°C and continue grinding for 3 hours;

4. The substance obtained after grinding in step 3 was washed once with ether and tetrahydrofuran respectively, then placed in a vacuum drying oven, and dried at 50° C. for 2 hours to obtain AlH ₃ .

Example 7

A kind of low-heat solid-phase synthesis AlH _of the present embodiment method, described method is carried out under anhydrous and oxygen-free conditions, and concrete steps are as follows:

1. Weigh LiAlH ₄ , LiBH ₄ and AlCl ₃ with a molar ratio of 9:1:1 in the glove box and mix them to obtain the mixture;

2. Grind the mixture of step 1 in an agate mortar and grind it in a sand bath, and raise the temperature to 72°C at a heating rate of 1°C/min;

3. Keep the temperature at 72°C and continue grinding for 3 hours;

4. The substance obtained after grinding in step 3 was washed once with ether and tetrahydrofuran respectively, then placed in a vacuum drying oven, and dried at 50° C. for 2 hours to obtain AlH ₃ .

Example 8

A kind of low-heat solid-phase synthesis AlH _of the present embodiment method, described method is carried out under anhydrous and oxygen-free conditions, and concrete steps are as follows:

1. Weigh and mix LiAlH ₄ , LiBH ₄ and AlCl ₃ with a molar ratio of 10:1:1 in a glove box to obtain a mixture;

2. Grind the mixture of step 1 in an agate mortar and grind it in a sand bath, and raise the temperature to 72°C at a heating rate of 1°C/min;

3. Keep the temperature at 72°C and continue grinding for 3 hours;

4. The substance obtained after grinding in step 3 was washed once with ether and tetrahydrofuran respectively, then placed in a vacuum drying oven, and dried at 50° C. for 2 hours to obtain AlH ₃ .

All of the above Examples 1 to 8 can prepare α-AlH ₃ with excellent properties.

Finally, it should be noted that the above examples are only descriptions of the preferred embodiments of the present invention and do not limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art will understand that the present invention can be The technical solution of the invention shall be modified or equivalently replaced without departing from the spirit and scope of the technical solution of the present invention.

Claims (10)

1. a kind of rare earth synthesizes AlH₃Method, it is characterised in that methods described is carried out under the conditions of anhydrous and oxygen-free, specific step It is rapid as follows：

First, mol ratio is weighed in glove box for (4~10):1:1 LiAlH₄、LiBH₄And AlCl₃After mixing, mixture is obtained；

2nd, the mixture of step one is ground and carried out in process of lapping in sand-bath in agate mortar, by 1 DEG C/min Heating rate be warming up to 65~80 DEG C；

3rd, 65~80 DEG C are maintained the temperature at, continues to grind 1~3h；

4th, the material obtained after step 3 is ground washed once with ether and tetrahydrofuran respectively, be subsequently placed in vacuum drying In case, 2h is dried under conditions of temperature is 50 DEG C, AlH is produced₃。

2. a kind of rare earth synthesis AlH according to claim 1₃Method, it is characterised in that LiAlH₄、LiBH₄With AlCl₃Mol ratio be (4~9):1:1.

3. a kind of rare earth synthesis AlH according to claim 2₃Method, it is characterised in that LiAlH₄、LiBH₄With AlCl₃Mol ratio be (4~8):1:1.

4. a kind of rare earth synthesis AlH according to claim 3₃Method, it is characterised in that LiAlH₄、LiBH₄With AlCl₃Mol ratio be (4~7):1:1.

5. a kind of rare earth synthesis AlH according to claim 4₃Method, it is characterised in that LiAlH₄、LiBH₄With AlCl₃Mol ratio be (4~6):1:1.

6. a kind of rare earth synthesis AlH according to claim 5₃Method, it is characterised in that LiAlH₄、LiBH₄With AlCl₃Mol ratio be 5:1:1.

7. a kind of rare earth synthesis AlH according to claim 1₃Method, it is characterised in that the heating and insulation Mode is sand-bath.

8. a kind of rare earth synthesis AlH according to claim 1₃Method, it is characterised in that in step 2 and step 3 Temperature be 65~75 DEG C.

9. a kind of rare earth synthesis AlH according to claim 8₃Method, it is characterised in that in step 2 and step 3 Temperature be 65~70 DEG C.

10. a kind of rare earth synthesis AlH according to claim 9₃Method, it is characterised in that step 2 and step 3 In temperature be 68 DEG C.