CN102718740A

CN102718740A - Trioxymethylene crystallization method

Info

Publication number: CN102718740A
Application number: CN2012102005301A
Authority: CN
Inventors: 张英伟; 王耀红; 孙长江; 陈伟长
Original assignee: BEIJING XUYANG CHEMICAL TECHNOLOGY RESEARCH INSTITUTE Co Ltd
Current assignee: BEIJING RISUN TECHNOLOGY CO., LTD.
Priority date: 2012-06-14
Filing date: 2012-06-14
Publication date: 2012-10-10
Anticipated expiration: 2032-06-14
Also published as: CN102718740B

Abstract

The invention relates to a trioxymethylene crystallization method and particularly provides a crystallization method for obtaining high-purity trioxymethylene. The method includes the steps: a) adding molten trioxymethylene and organic solvent at 30-35 DEG C into a container with a stirrer, well mixing, cooling by water bath at 30-35 DEG C, stirring for 2-8h, cooling by water bath at 18-25 DEG C, and stirring 1-4h to enable trioxymethylene to seed out; b) adding trioxymethylene suspension into a filter, standing, and subjecting the lower layer of the standing suspension to vacuum filtering; and c) adding solid obtained by filtering at the step b) into a drier to remove the residue solvent to obtain the trioxymethylene product. Trioxymethylene crystals obtained by the method are convenient for transport and storage, so that remote selling of the trioxymethylene is facilitated.

Description

A kind of crystallization method of trioxymethylene

Technical field

The present invention relates to a kind of crystallization method, particularly the crystallization method of trioxymethylene.

Background technology

Trioxymethylene is a kind of important chemical material; Of many uses; Be mainly used in first raw material monomer of engineering plastics copolymerized methanal, also can be used for preparing anhydrous formaldehyde and stablizer, smoke fumigant, sterilant, formed material, sticker, sterilizing agent, antimicrobial drug etc.Trioxymethylene can depolymerization generate formaldehyde, so it almost completely can be used for all formolite reactions, particularly when the needs anhydrous formaldehyde was made reagent, its application was more valuable.

Present trioxymethylene is also fewer as commodity selling; Trioxymethylene crystallization processes bibliographical information is less; Yunnan Yuntianhua Co., Ltd. adopts the continuous process for freezing and crystallizing of trioxymethylene of Poland's introduction, and its original tank crystallizer is transformed into double-pipe crystallizer (patent publication No. CN101074225).Reduce facility investment, reduced energy consumption, obtained certain correctional effect.But the cooling water in its double-pipe crystallizer is subzero 10 to subzero 13 ℃, needs special refrigeration equipment certainly will increase production cost of products.And be the middle portion in the trioxymethylene production process, do not obtain highly purified trioxymethylene product (content of trioxymethylene is merely 94.8%).

How low through energy consumption, technical process short, the process cost inexpensive method realizes the trioxymethylene crystallization, and obtains stable performance, grain fineness number is more even, purity is high, satisfies the market requirements such as anhydrous formaldehyde, is the emphasis and the difficult point of trioxymethylene crystallization method.

Summary of the invention

Technical purpose

The purpose of this invention is to provide a kind of crystallization method that obtains highly purified trioxymethylene, be convenient to transportation and storage, for the remote sale of trioxymethylene offers convenience through the trioxymethylene xln that method of the present invention obtains.

Technical scheme

To achieve these goals, the invention provides a kind of crystallization method of trioxymethylene, this method may further comprise the steps:

A) organic solvent of molten state trioxymethylene and 30-35 ℃ is put into the container that has whisking appliance; After mixing, (once cooling) cooled off in the water-bath of using 30-35 ℃, behind the stirring 2-8h; (secondary cooling) cooled off in the water-bath that re-uses 18-25 ℃; After stirring 1-4h the trioxymethylene crystallization is separated out, wherein the temperature of molten state trioxymethylene is 70-90 ℃, and said organic solvent is methyl alcohol, ethanol, toluene, benzene, ether, acetone, ETHYLE ACETATE or its arbitrary combination; The weight ratio of said trioxymethylene and organic solvent is 20:1-1:5, is preferably 5:1-1:3; Do not limit said container is special, can be mold commonly used in the industry;

B) trioxymethylene suspension-s is put into filtration unit, after leaving standstill, the lower floor of leaving standstill suspension-s is carried out vacuum filtration; Wherein filtration temperature is 20-30 ℃; Vacuum tightness 0.03-0.095MPa, the supernatant that leaves standstill suspension-s can be recycled with filtrating, as being used as the organic solvent in the step a); Do not limit said filtration unit is special, it can be vacuum filter commonly used;

C) above-mentioned steps is filtered the gained solid and put into moisture eliminator to remove remaining solvent; Thereby obtain the trioxymethylene product; Wherein gained trioxymethylene product gas purity can reach 99.00-99.99wt%, and the solvent of dried recovered can be recycled, as being used as the organic solvent in the step a).

Beneficial effect

The present invention has following advantage:

1) above-mentioned technology institute use equipment is conventional equipment, does not want special processing, reduce facility investment, and technical process is simple, and overall investment is less;

2) do not need refrigerating apparatus, heating installation in the industry, can adopt and produce needed industrial circulating water of trioxymethylene and primary water, energy consumption is low, and working cost is low;

3) constant product quality, the crystallization uniformity coefficient is high, and purity is high, does not have insolubles to generate;

4) organic solvent can reuse, not loss;

5) environmentally friendly, three-waste free discharge.

Description of drawings

Fig. 1 is the schema of trioxymethylene crystallization method of the present invention.

Embodiment

Molten state trioxymethylene among the following embodiment is the molten state trioxymethylene that Hebei province's coal chemical industry engineering Technical Research Center trioxymethylene production line is produced, and the purity of trioxymethylene is 99.96%.Purity among the following embodiment is measured and is adopted Agilent company gc 7890 quantitative, and methylal, formaldehyde adopt gc quantitative equally, and the quantivative approach of formic acid, formaldehyde all adopts chemical titration.

Embodiment 1

In the 1L round-bottomed flask, add 80 ℃ of molten state trioxymethylene 400g, add 30 ℃ fresh methanol (that is, the methyl alcohol of non-recovery) 160g, mix and place 30 ℃ of water crystallisation by cooling; Stir 3h, be cooled to 20 ℃ to water temperature then, under 20 ℃, mix 1h, stop to stir; Pour out supernatant liquid, 25 ℃ of following vacuum filtrations of lower floor are after the filtration; Control vacuum tightness is-0.06MPa in Rotary Evaporators, 30 ℃ of following dry 3h, discharging; The product of weighing and obtaining, this product crystal is tiny, uniform particles.Quality is 239g, yield 59.75%.Trioxymethylene purity is 99.8wt%, formic acid content 30ppm, formaldehyde content 60ppm, methylal content 30ppm, methanol content 200ppm.

The low reason of trioxymethylene crystal yield that obtains in this embodiment has been to use fresh methyl alcohol, and the trioxymethylene of part is dissolved in the methanol solution that has formed saturated trioxymethylene in the methyl alcohol.

Embodiment 2

Method is with embodiment 1 trioxymethylene consumption 243g, methanol solution (methyl alcohol of recovery) consumption 360g.Obtain solid 241.9g, yield 99.5%.Polyoxymethylene purity is 99.75wt%, formic acid content 40ppm, and formaldehyde content 55ppm, methylal content does not detect, methanol content 220ppm.

Because used the methyl alcohol of recycling, that is, the saturated solution of methyl alcohol is so the product yield that obtains is very high in this embodiment.

Embodiment 3

Method is with embodiment 2, trioxymethylene consumption 239.7g, and be 5h time of drying, obtains crystal 2 38.1g, yield 99.33%.Trioxymethylene purity is 99.75wt%, formic acid content 38ppm, formaldehyde content 63ppm, methylal content 20ppm, methanol content 120ppm.

Embodiment 4

Method is with embodiment 1, and employing ethanol is solvent, and the solid that obtains trioxymethylene is 230g, and yield is 57.5%.Trioxymethylene purity is 99.6%, formic acid content 30ppm, and formaldehyde content 60ppm, methylal content 30ppm, ethanol content 1000ppm, the content of methyl alcohol are 40ppm.

Embodiment 5

Method is with embodiment 2, and adopting the ethanol that reclaims is solvent, and the solid that obtains trioxymethylene is 241.3g, and yield is 99.3%.Trioxymethylene purity is 99.7wt%, formic acid content 30ppm, and formaldehyde content 40ppm, methylal content 12ppm, ethanol content 366ppm, the content of methyl alcohol are 22ppm.

Embodiment 6

Method is with embodiment 1, and employing benzene is solvent, and the add-on of trioxymethylene is 300g, and the add-on of benzene is 300g, and the solid that obtains trioxymethylene is 130g, and yield is 43.3%.Trioxymethylene purity is 99.9wt%, formic acid content 30ppm, and formaldehyde content 60ppm, methylal content 30ppm, the content of benzene are 160ppm, the content of methyl alcohol is 20ppm.

Embodiment 7

Method is with embodiment 2, and adopting the benzene that reclaims is solvent, and the add-on of trioxymethylene is 130g, and the add-on of benzene is 470g, and the solid that obtains trioxymethylene is 129.6g, and yield is 99.69%.Trioxymethylene purity is 99.91wt%, formic acid content 30ppm, and formaldehyde content 50ppm, methylal content 10ppm, content of toluene is 220ppm, the content of methyl alcohol is 10ppm.

Claims

1. the crystallization method of a trioxymethylene, this method may further comprise the steps:

A) organic solvent of molten state trioxymethylene and 30-35 ℃ is put into the container that has whisking appliance; After mixing, use 30-35 ℃ water-bath to cool off, behind the stirring 2-8h; The water-bath that re-uses 18-25 ℃ is cooled off, and behind the stirring 1-4h trioxymethylene crystallization is separated out;

B) trioxymethylene suspension-s is put into filtration unit, after leaving standstill, the lower floor of leaving standstill suspension-s is carried out vacuum filtration;

C) with above-mentioned steps c) filter the gained solid and put into moisture eliminator removing remaining solvent, thus obtain the trioxymethylene product.

2. crystallization method according to claim 1, wherein, the temperature of said molten state formaldehyde is 70-90 ℃.

3. crystallization method according to claim 1, wherein, said organic solvent is methyl alcohol, ethanol, toluene, benzene, ether, acetone, ETHYLE ACETATE or its arbitrary combination.

4. crystallization method according to claim 1, wherein, the weight ratio of said trioxymethylene and organic solvent is 20:1-1:5.

5. crystallization method according to claim 4, wherein, the weight ratio of said trioxymethylene and organic solvent is 5:1-1:3.

6. crystallization method according to claim 1, wherein, the filtration temperature in the step b) is 20-30 ℃, and vacuum tightness 0.03-0.095MPa.

7. crystallization method according to claim 1, wherein, the organic solvent in step a) is supernatant that leaves standstill suspension-s and the filtrating in the step b), perhaps is the solvent of dried recovered in the step c).

8. trioxymethylene crystal according to each described crystallization method preparation in the claim 1～7.