阅读说明：本技术 一种甲缩醛提纯方法 (Methylal purification method ) 是由 陈康件 陈康成 李达 于 2020-12-29 设计创作，主要内容包括：本发明公开了一种甲缩醛提纯方法；涉及甲缩醛合成技术领域,包括以下步骤：(1)得到混合分散液；(2)将混合分散液在常温常压下进行精馏处理,得到甲缩醛和甲醇混合物；(3)得到煅烧硅藻土；(4)得到载体；(5)得到过滤体；(6)将甲缩醛和甲醇混合物通入过滤体中,进行吸附处理1-1.5小时,得到提纯甲缩醛；本发明方法能够极大的提高对甲缩醛混合物的提纯效果,得到纯度更高的甲缩醛。(The invention discloses a methylal purification method; relates to the technical field of methylal synthesis, which comprises the following steps: (1) obtaining a mixed dispersion liquid; (2) rectifying the mixed dispersion liquid at normal temperature and normal pressure to obtain a mixture of methylal and methanol; (3) obtaining calcined diatomite; (4) obtaining a carrier; (5) obtaining a filter body; (6) introducing a mixture of methylal and methanol into the filter body, and carrying out adsorption treatment for 1-1.5 hours to obtain purified methylal; the method can greatly improve the purification effect of the methylal mixture and obtain the methylal with higher purity.)

1. A method for purifying methylal is characterized by comprising the following steps:

(1) introducing the methylal mixture into deionized water, stirring for 30-40min, and standing for 1 hour to obtain a standing solution;

performing contact type water absorption treatment on the upper layer of the standing liquid by using a water absorbent, performing ultrasonic auxiliary treatment for 3-4min, and removing the water absorbent to obtain a mixed dispersion liquid;

(2) rectifying the mixed dispersion liquid at normal temperature and normal pressure to obtain a mixture of methylal and methanol;

(3) uniformly dispersing diatomite into a sodium hypochlorite solution, stirring at the rotating speed of 500r/min for 30-40min, adding sodium maleate, continuously stirring for 15-20min, then performing suction filtration, washing with clear water, and drying to constant weight to obtain pretreated diatomite;

calcining the pretreated diatomite for 35-40min in an inert atmosphere, cooling along with a furnace, grinding, and sieving with a 1250-mesh sieve to obtain calcined diatomite;

(4) preparing a carrier;

sequentially adding silica sol, aluminum nitrate, aluminum isopropoxide, tetrapropylammonium hydroxide, sodium hydroxide and calcined diatomite deionized water into a reaction kettle, heating to 90-96 ℃, preserving heat, stirring for 30min, discharging, and performing rotary evaporation drying to obtain a carrier;

(5) sequentially adding the carrier, 1-ethyl-3-methylimidazole tetrafluoroborate and N-ethylpyridine hexafluorophosphate into a vacuum impregnation reaction kettle, adjusting the temperature to 45-50 ℃, preserving the heat, stirring for 45-55min, discharging, and naturally cooling to room temperature to obtain a filter body;

(6) introducing the mixture of methylal and methanol into the filter body, and carrying out adsorption treatment for 1-1.5 hours to obtain purified methylal.

2. A method for purifying methylal according to claim 1, wherein: the mass ratio of the methylal mixture to the deionized water is 1: 10-12.

3. A method for purifying methylal according to claim 1, wherein: the water absorbent is silicic acid gel.

4. A method for purifying methylal according to claim 1, wherein: the ultrasonic frequency is 40kHz, and the power is 600W.

5. A method for purifying methylal according to claim 1, wherein: the mixing mass ratio of the diatomite to the sodium hypochlorite solution is 1: 4-5;

the mass fraction of the sodium hypochlorite solution is 5.8%;

the mass ratio of the sodium maleate to the diatomite is 1: 25-30.

6. A method for purifying methylal according to claim 1, wherein: the inert atmosphere is nitrogen atmosphere;

the calcination temperature is 670-.

7. A method for purifying methylal according to claim 1, wherein: the mixing mass ratio of the silica sol, aluminum nitrate, aluminum isopropoxide, tetrapropylammonium hydroxide, sodium hydroxide, calcined diatomite and deionized water is (30-33: 0.12:0.12: 1.6): 2.1: 15-17: 85.

8. a method for purifying methylal according to claim 1, wherein: the mixing mass ratio of the carrier to the 1-ethyl-3-methylimidazole tetrafluoroborate is 8: 1-1.2;

the mixing mass ratio of the 1-ethyl-3-methylimidazole tetrafluoroborate to the N-ethylpyridine hexafluorophosphate is 1: 2-3.

9. A method for purifying methylal according to claim 1, wherein: the mass ratio of the mixture of methylal and methanol to the filter body is 1: 12-15.

Technical Field

The invention belongs to the technical field of methylal synthesis, and particularly relates to a methylal purification method.

Background

Methylal (DMM), also known as dimethoxymethane and dimethanol formal, is used as a chemical raw material and an intermediate due to the molecular structure and unique physicochemical properties of C-O bond connection.

The methylal has small toxicity and good solubility, has great application value in the aspects of environmental protection and energy chemical industry, can be applied to diesel additives, can effectively reduce the emission of nitrides and particles in the tail gas of the diesel engine, can improve the combustion performance of the dye, increases the thermal efficiency of the dye and achieves the effect of saving energy.

The methylal is synthesized by mixing formaldehyde and methanol, but the obtained methylal contains methanol and formaldehyde, and a mixture of the methanol and the formaldehyde needs to be purified to obtain methylal with higher purity because the reaction is in dynamic equilibrium, but the methylal and the methanol form an azeotrope with the lowest boiling point under normal pressure, the mass fraction of the methylal in the azeotrope is 94.03%, and further separation and purification are not easy to perform, so that further purification improvement treatment needs to be performed to improve the purity of the methylal.

Disclosure of Invention

The invention aims to provide a methylal purification method to solve the defects in the prior art.

The technical scheme adopted by the invention is as follows:

a method for purifying methylal comprises the following steps:

(1) introducing the methylal mixture into deionized water, stirring for 30-40min, and standing for 1 hour to obtain a standing solution;

performing contact type water absorption treatment on the upper layer of the standing liquid by using a water absorbent, performing ultrasonic auxiliary treatment for 3-4min, and removing the water absorbent to obtain a mixed dispersion liquid;

(2) rectifying the mixed dispersion liquid at normal temperature and normal pressure to obtain a mixture of methylal and methanol;

(3) uniformly dispersing diatomite into a sodium hypochlorite solution, stirring at the rotating speed of 500r/min for 30-40min, adding sodium maleate, continuously stirring for 15-20min, then performing suction filtration, washing with clear water, and drying to constant weight to obtain pretreated diatomite;

calcining the pretreated diatomite for 35-40min in an inert atmosphere, cooling along with a furnace, grinding, and sieving with a 1250-mesh sieve to obtain calcined diatomite;

(4) preparing a carrier;

sequentially adding silica sol, aluminum nitrate, aluminum isopropoxide, tetrapropylammonium hydroxide, sodium hydroxide and calcined diatomite deionized water into a reaction kettle, heating to 90-96 ℃, preserving heat, stirring for 30min, discharging, and performing rotary evaporation drying to obtain a carrier;

(5) sequentially adding the carrier, 1-ethyl-3-methylimidazole tetrafluoroborate and N-ethylpyridine hexafluorophosphate into a vacuum impregnation reaction kettle, adjusting the temperature to 45-50 ℃, preserving the heat, stirring for 45-55min, discharging, and naturally cooling to room temperature to obtain a filter body; the vacuum degree is 0.015 MPa;

(6) introducing the mixture of methylal and methanol into the filter body, and carrying out adsorption treatment for 1-1.5 hours to obtain purified methylal.

The mass ratio of the methylal mixture to the deionized water is 1: 10-12.

The water absorbent is silicic acid gel.

The ultrasonic frequency is 40kHz, and the power is 600W.

The mixing mass ratio of the diatomite to the sodium hypochlorite solution is 1: 4-5;

the mass fraction of the sodium hypochlorite solution is 5.8%;

the mass ratio of the sodium maleate to the diatomite is 1: 25-30.

The inert atmosphere is nitrogen atmosphere;

the calcination temperature is 670-.

The mixing mass ratio of the silica sol, aluminum nitrate, aluminum isopropoxide, tetrapropylammonium hydroxide, sodium hydroxide, calcined diatomite and deionized water is (30-33: 0.12:0.12: 1.6): 2.1: 15-17: 85.

the mixing mass ratio of the carrier to the 1-ethyl-3-methylimidazole tetrafluoroborate is 8: 1-1.2;

the mixing mass ratio of the 1-ethyl-3-methylimidazole tetrafluoroborate to the N-ethylpyridine hexafluorophosphate is 1: 2-3.

The mass ratio of the mixture of methylal and methanol to the filter body is 1: 12-15.

The filter body prepared by the method has selective dissolving and absorbing effects on methanol in a methylal mixture, and the filter body is used as an absorbent, aiming at the molecular structure characteristics of methanol gas in the methylal mixture, 1-ethyl-3-methylimidazolium tetrafluoroborate and N-ethylpyridine hexafluorophosphate are mixed according to a certain mass ratio and then compounded in a carrier, so that the selective absorbing capacity of the filter body on the methanol can be greatly enhanced, the purification effect on the methylal mixed gas can be greatly improved, and the purity of the methylal is improved, and the filter body mainly shows that: the methanol molecules have charge density distribution mostly in a non-polar region and have charge density distribution in a wide range, and can be regarded as an H bond donor region and an H bond acceptor, so that hydrogen bonds can be formed between the methanol molecules and the filter prepared by the method of the invention to generate interaction, and the effect of selectively absorbing the methanol molecules is achieved.

Has the advantages that:

the method can greatly improve the purification effect of the methylal mixture, obtain the methylal with higher purity, and has great widening effect on the application field of the methylal. According to the method, the mixed mass ratio of the 1-ethyl-3-methylimidazolium tetrafluoroborate to the N-ethylpyridine hexafluorophosphate is adjusted, and the mixed mass ratio is compounded in a certain mass ratio, so that the prepared filter body can greatly improve the purification effect of methylal, the adsorption effect of the filter body on methanol is remarkably improved, the purification effect of methylal can be greatly improved, and methylal with higher purity can be obtained.

Detailed Description

A method for purifying methylal comprises the following steps:

(1) introducing the methylal mixture into deionized water, stirring for 30-40min, and standing for 1 hour to obtain a standing solution;

performing contact type water absorption treatment on the upper layer of the standing liquid by using a water absorbent, performing ultrasonic auxiliary treatment for 3-4min, and removing the water absorbent to obtain a mixed dispersion liquid;

(2) rectifying the mixed dispersion liquid at normal temperature and normal pressure to obtain a mixture of methylal and methanol;

(3) uniformly dispersing diatomite into a sodium hypochlorite solution, stirring at the rotating speed of 500r/min for 30-40min, adding sodium maleate, continuously stirring for 15-20min, then performing suction filtration, washing with clear water, and drying to constant weight to obtain pretreated diatomite;

calcining the pretreated diatomite for 35-40min in an inert atmosphere, cooling along with a furnace, grinding, and sieving with a 1250-mesh sieve to obtain calcined diatomite;

(4) preparing a carrier;

sequentially adding silica sol, aluminum nitrate, aluminum isopropoxide, tetrapropylammonium hydroxide, sodium hydroxide and calcined diatomite deionized water into a reaction kettle, heating to 90-96 ℃, preserving heat, stirring for 30min, discharging, and performing rotary evaporation drying to obtain a carrier;

(5) sequentially adding the carrier, 1-ethyl-3-methylimidazole tetrafluoroborate and N-ethylpyridine hexafluorophosphate into a vacuum impregnation reaction kettle, adjusting the temperature to 45-50 ℃, preserving the heat, stirring for 45-55min, discharging, and naturally cooling to room temperature to obtain a filter body; the vacuum degree is 0.015 MPa;

(6) introducing the mixture of methylal and methanol into the filter body, and carrying out adsorption treatment for 1-1.5 hours to obtain purified methylal.

The mass ratio of the methylal mixture to the deionized water is 1: 10-12.

The water absorbent is silicic acid gel.

The ultrasonic frequency is 40kHz, and the power is 600W.

The mixing mass ratio of the diatomite to the sodium hypochlorite solution is 1: 4-5;

the mass fraction of the sodium hypochlorite solution is 5.8%;

the mass ratio of the sodium maleate to the diatomite is 1: 25-30.

The inert atmosphere is nitrogen atmosphere;

the calcination temperature is 670-.

The mixing mass ratio of the silica sol, aluminum nitrate, aluminum isopropoxide, tetrapropylammonium hydroxide, sodium hydroxide, calcined diatomite and deionized water is (30-33: 0.12:0.12: 1.6): 2.1: 15-17: 85.

the mixing mass ratio of the carrier to the 1-ethyl-3-methylimidazole tetrafluoroborate is 8: 1-1.2;

the mixing mass ratio of the 1-ethyl-3-methylimidazole tetrafluoroborate to the N-ethylpyridine hexafluorophosphate is 1: 2-3.

The mass ratio of the mixture of methylal and methanol to the filter body is 1: 12-15.

The following will clearly and completely describe the technical solutions of the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

A method for purifying methylal comprises the following steps:

(1) introducing the methylal mixture into deionized water, stirring for 30min, and then standing for 1 hour to obtain standing liquid; performing contact type water absorption treatment on the upper layer of the standing liquid by using a water absorbent, performing ultrasonic auxiliary treatment for 3min, and removing the water absorbent to obtain a mixed dispersion liquid; the mass ratio of the methylal mixture to the deionized water is 1: 10. The water absorbent is silicic acid gel. The ultrasonic frequency is 40kHz, and the power is 600W.

(2) Rectifying the mixed dispersion liquid at normal temperature and normal pressure to obtain a mixture of methylal and methanol;

(3) uniformly dispersing diatomite into a sodium hypochlorite solution, stirring at the rotating speed of 500r/min for 30min, adding sodium maleate, continuously stirring for 15min, then carrying out suction filtration, washing with clear water, and drying to constant weight to obtain pretreated diatomite; calcining the pretreated diatomite for 35min in an inert atmosphere, then cooling along with a furnace, grinding, and sieving with a 1250-mesh sieve to obtain calcined diatomite; the mixing mass ratio of the diatomite to the sodium hypochlorite solution is 1: 4; the mass fraction of the sodium hypochlorite solution is 5.8%; the mass ratio of the sodium maleate to the diatomite is 1: 25. The inert atmosphere is nitrogen atmosphere; the calcination temperature was 670 ℃.

(4) Preparing a carrier;

sequentially adding silica sol, aluminum nitrate, aluminum isopropoxide, tetrapropylammonium hydroxide, sodium hydroxide and calcined diatomite deionized water into a reaction kettle, heating to 90 ℃, preserving heat, stirring for 30min, discharging, and performing rotary evaporation drying to obtain a carrier; the mixing mass ratio of the silica sol, aluminum nitrate, aluminum isopropoxide, tetrapropylammonium hydroxide, sodium hydroxide, calcined diatomite and deionized water is 30:0.12:0.12: 1.6: 2.1: 15: 85.

(5) sequentially adding the carrier, 1-ethyl-3-methylimidazole tetrafluoroborate and N-ethylpyridine hexafluorophosphate into a vacuum impregnation reaction kettle, adjusting the temperature to 45 ℃, preserving the temperature, stirring for 45-55min, discharging, and naturally cooling to room temperature to obtain a filter body; the mixing mass ratio of the carrier to the 1-ethyl-3-methylimidazole tetrafluoroborate is 8: 1; the mixing mass ratio of the 1-ethyl-3-methylimidazole tetrafluoroborate to the N-ethylpyridine hexafluorophosphate is 1: 2; the vacuum degree is 0.015 MPa;

(6) and introducing a mixture of methylal and methanol into the filter body, and carrying out adsorption treatment for 1 hour to obtain purified methylal.

The mass ratio of the mixture of methylal and methanol to the filter body is 1: 12.

Example 2

A method for purifying methylal comprises the following steps:

(1) introducing the methylal mixture into deionized water, stirring for 40min, and then standing for 1 hour to obtain standing liquid; performing contact type water absorption treatment on the upper layer of the standing liquid by using a water absorbent, performing ultrasonic auxiliary treatment for 4min, and removing the water absorbent to obtain a mixed dispersion liquid; the mass ratio of the methylal mixture to the deionized water is 1: 12. The water absorbent is silicic acid gel. The ultrasonic frequency is 40kHz, and the power is 600W.

(2) Rectifying the mixed dispersion liquid at normal temperature and normal pressure to obtain a mixture of methylal and methanol;

(3) uniformly dispersing diatomite into a sodium hypochlorite solution, stirring at the rotating speed of 500r/min for 40min, adding sodium maleate, continuously stirring for 20min, then carrying out suction filtration, washing with clear water, and drying to constant weight to obtain pretreated diatomite; calcining the pretreated diatomite for 40min in an inert atmosphere, then cooling along with a furnace, grinding, and sieving with a 1250-mesh sieve to obtain calcined diatomite; the mixing mass ratio of the diatomite to the sodium hypochlorite solution is 1: 5; the mass fraction of the sodium hypochlorite solution is 5.8%; the mass ratio of the sodium maleate to the diatomite is 1: 30. The inert atmosphere is nitrogen atmosphere; the calcination temperature was 690 ℃.

(4) Preparing a carrier;

sequentially adding silica sol, aluminum nitrate, aluminum isopropoxide, tetrapropylammonium hydroxide, sodium hydroxide and calcined diatomite deionized water into a reaction kettle, heating to 96 ℃, preserving heat, stirring for 30min, discharging, and performing rotary evaporation drying to obtain a carrier; the mixing mass ratio of the silica sol, aluminum nitrate, aluminum isopropoxide, tetrapropylammonium hydroxide, sodium hydroxide, calcined diatomite to deionized water is 33:0.12:0.12: 1.6: 2.1: 17: 85.

(5) sequentially adding the carrier, 1-ethyl-3-methylimidazole tetrafluoroborate and N-ethylpyridine hexafluorophosphate into a vacuum impregnation reaction kettle, adjusting the temperature to 50 ℃, preserving the temperature, stirring for 55min, discharging, and naturally cooling to room temperature to obtain a filter body; the mixing mass ratio of the carrier to the 1-ethyl-3-methylimidazole tetrafluoroborate is 8: 1.2; the mixing mass ratio of the 1-ethyl-3-methylimidazole tetrafluoroborate to the N-ethylpyridine hexafluorophosphate is 1: 3; the vacuum degree is 0.015 MPa;

(6) the mixture of methylal and methanol was passed through the filter and subjected to adsorption treatment for 1.5 hours to obtain purified methylal.

The mass ratio of the mixture of methylal and methanol to the filter body is 1: 15.

Example 3

A method for purifying methylal comprises the following steps:

(1) introducing the methylal mixture into deionized water, stirring for 34min, and then standing for 1 hour to obtain standing liquid; performing contact type water absorption treatment on the upper layer of the standing liquid by using a water absorbent, performing ultrasonic auxiliary treatment for 3.5min, and removing the water absorbent to obtain a mixed dispersion liquid; the mass ratio of the methylal mixture to the deionized water is 1: 11. The water absorbent is silicic acid gel. The ultrasonic frequency is 40kHz, and the power is 600W.

(2) Rectifying the mixed dispersion liquid at normal temperature and normal pressure to obtain a mixture of methylal and methanol;

(3) uniformly dispersing diatomite into a sodium hypochlorite solution, stirring at the rotating speed of 500r/min for 32min, adding sodium maleate, continuously stirring for 18min, then carrying out suction filtration, washing with clear water, and drying to constant weight to obtain pretreated diatomite; calcining the pretreated diatomite for 38min in an inert atmosphere, then cooling along with a furnace, grinding, and sieving with a 1250-mesh sieve to obtain calcined diatomite; the mixing mass ratio of the diatomite to the sodium hypochlorite solution is 1: 4.5; the mass fraction of the sodium hypochlorite solution is 5.8%; the mass ratio of the sodium maleate to the diatomite is 1: 27. The inert atmosphere is nitrogen atmosphere; the calcination temperature was 682 ℃.

(4) Preparing a carrier;

sequentially adding silica sol, aluminum nitrate, aluminum isopropoxide, tetrapropylammonium hydroxide, sodium hydroxide and calcined diatomite deionized water into a reaction kettle, heating to 93 ℃, preserving heat, stirring for 30min, discharging, and performing rotary evaporation drying to obtain a carrier; the mixing mass ratio of the silica sol, aluminum nitrate, aluminum isopropoxide, tetrapropylammonium hydroxide, sodium hydroxide, calcined diatomite to deionized water is (32: 0.12:0.12: 1.6): 2.1: 16.2: 85.

(5) sequentially adding the carrier, 1-ethyl-3-methylimidazole tetrafluoroborate and N-ethylpyridine hexafluorophosphate into a vacuum impregnation reaction kettle, adjusting the temperature to 48 ℃, preserving the temperature, stirring for 51min, discharging, and naturally cooling to room temperature to obtain a filter body; the mixing mass ratio of the carrier to the 1-ethyl-3-methylimidazole tetrafluoroborate is 8: 1.1; the mixing mass ratio of the 1-ethyl-3-methylimidazole tetrafluoroborate to the N-ethylpyridine hexafluorophosphate is 1: 2.5; the vacuum degree is 0.015 MPa;

(6) the mixture of methylal and methanol was passed through the filter and subjected to adsorption treatment for 1.2 hours to obtain purified methylal.

The mass ratio of the mixture of methylal and methanol to the filter body is 1: 13.5.

The mass fraction of methylal in the sample methylal mixture is 92.35%;

respectively treating the samples by adopting the methods of examples and comparative examples, and comparing the purity of the purified methylal after each group of treatment;

TABLE 1

	Purity of purified methylal%
		Example 1	99.28
Example 2	99.31
		Example 3	99.65
Comparative example 1	98.18
		Comparative example 2	96.71

Comparative example 1: the difference from example 1 is that no calcined diatomaceous earth is added;

comparative example 2: the difference from example 1 is that no N-ethylpyridine hexafluorophosphate salt is added;

as can be seen from Table 1, the method of the invention can greatly improve the purification effect of the methylal mixture, obtain methylal with higher purity, and has great broadening effect on the application field of the methylal mixture.

Based on the sample of example 3, the influence of the mass ratio of the filter body prepared by different mixing mass ratios of 1-ethyl-3-methylimidazolium tetrafluoroborate and N-ethylpyridine hexafluorophosphate on the methylal purification effect is compared;

TABLE 2

1-ethyl-3-methylimidazolium tetrafluoroborate and N-ethylpyridine hexafluorophosphate in a mixed mass ratio	Purity of purified methylal%
		1:1	98.24
1:2	99.40
		1:2.5	99.65
1:3	99.56
		1:4	98.93

Table 2 shows that, in the method of the present invention, by adjusting the mixing mass ratio of the 1-ethyl-3-methylimidazolium tetrafluoroborate to the N-ethylpyridinium hexafluorophosphate, and compounding the salts at a certain mass ratio, the purification effect of the prepared filter body on methylal can be greatly improved, and the adsorption effect on methanol is significantly increased, so that the purification effect of methylal can be greatly improved, and methylal with higher purity can be obtained.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention, and the present invention is not limited to the illustrated embodiments, and all the modifications and equivalents of the embodiments may be made without departing from the spirit of the present invention.