CN211946867U - Device for preparing high-purity methylal by synchronously operating extraction and rectification - Google Patents
Device for preparing high-purity methylal by synchronously operating extraction and rectification Download PDFInfo
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- CN211946867U CN211946867U CN202020321247.4U CN202020321247U CN211946867U CN 211946867 U CN211946867 U CN 211946867U CN 202020321247 U CN202020321247 U CN 202020321247U CN 211946867 U CN211946867 U CN 211946867U
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Abstract
The utility model discloses a device of extraction and rectification synchronous operation's preparation high purity methylal, the main part is the rectifying column: the top is equipped with extractant import, well below in the tower wall and is equipped with raw materials methylal import, and the top of opposite side tower wall is equipped with the backward flow mouth, and the top of the tower is equipped with discharge gate I, and the tower cauldron is equipped with discharge gate II: the extractant inlet is connected with a device capable of providing an extractant; the raw material methylal inlet is connected with a device capable of providing the raw material methylal; the discharge port I is connected with a condenser, the outlet of the condenser is divided into two paths, one path is connected with a reflux port, and the other path is connected with a device for collecting high-purity methylal; the discharge port II is connected with a device for collecting tower kettle liquid; the tower kettle is provided with a reboiler. Raw material methylal enters the rectifying tower from a raw material methylal inlet at the lower part in the tower wall, an extracting agent enters the rectifying tower from an extracting agent inlet at the upper part in the tower wall, the extracting agent and the raw material methylal are in reverse contact, and extraction and rectification can be synchronously carried out.
Description
Technical Field
The utility model relates to a device for preparing high-purity methylal, in particular to a device for preparing high-purity methylal, which synchronously operates by extraction and rectification; the formaldehyde aqueous solution containing alkali and salt is used as an extracting agent to remove impurities such as methanol, formic acid, methyl formate and the like in methylal to prepare high-purity methylal with the content of more than 99.95 percent by weight. The utility model is suitable for a field of preparing of methylal especially is suitable for the high-purity methylal that does not contain formic acid and methyl formate of preparation.
Background
Methylal, also known as formaldehyde dimethyl acetal, dimethoxymethane. Structural formula CH2(OCH3)2Melting point: -104.8 ℃, boiling point: 42.3 ℃, density: 0.8593 g/ml.
Methylal is widely used in industry as a less toxic and environment-friendly excellent solvent. The methylal can be used for quantitative dissolution of grease, wax, nitrocellulose, synthetic resin, polystyrene, vinyl acetate polymer and copolymer, polyester, epoxy resin, chlorinated rubber and the like. The methylal is mixed with ethanol, ester or ketone to obtain a synergistic effect on the solvent, so that the product can obtain an excellent uniform phase when used as an additive in paint and varnish formulations, glue and adhesives, printing ink and various aerosol products. The methylal can replace Freon to be used as a solvent for dissolving the high-molecular polyacrylate solid raw material in a color belt formula and an electronic equipment cleaning agent formula. The methylal can replace chlorine-containing solvents to be used for dissolving the tetramethrin, the chlocidin, the high-efficiency cypermethrin and the deltamethrin quasi-insecticidal pyrethrin pesticide formulas. Methylal is also widely used in leather polishes and air fresheners.
At present, the industrial preparation method and process of methylal are mature and simple, and methylal is prepared in a catalytic distillation tower by mainly using methanol and formaldehyde aqueous solution as raw materials and hydrogen type cation exchange resin as a catalyst, wherein the catalytic distillation tower is divided into three sections from top to bottom: a rectifying section, a catalytic reaction section (catalyst module) and a stripping section in sequence. Raw material formaldehyde aqueous solution enters from the upper part of the reaction section, raw material methanol enters from the lower part of the reaction section, methanol gas and formaldehyde aqueous solution reversely contact in the reaction section and react under the action of a catalyst to generate methylal, the methylal is extracted from the top of the tower, and wastewater is extracted from the bottom of the tower. The operating conditions of the catalytic distillation column were: the temperature at the top of the tower is controlled to be 40-45 ℃, the reflux ratio is 1.0-1.5, and the pressure is normal pressure; the temperature of the reaction section is controlled to be 55-85 ℃; the temperature of the tower kettle is controlled to be 98-110 ℃.
Since methylal forms an azeotropic mixture with methanol, methyl formate and the like, only methylal with methylal purity of 88-92% can be obtained by the method, and the balance is methanol, methyl formate and the like. Low purity methylal can only be used in general fields. If high purity methylal is desired, the obtained methylal with low purity needs to be further refined and purified. For example, CN102371079A discloses a pressurized rectification process and a preparation device for high-concentration methylal, wherein crude methylal is rectified at a pressure of 0.5 to 1.0MPa, high-purity methylal is extracted from a tower bottom, and an azeotrope of methylal and methanol is extracted from a tower top and returned to a methylal synthesis device. The principle of extraction and rectification is to remove impurities such as methanol in methylal by using a solvent which has higher solubility to the impurities such as methanol as an extracting agent than the methylal so as to achieve the purpose of improving the purity of the methylal. For example, the preparation of high-purity methylal by extraction and rectification of jade and the like with N, N-dimethylformamide as a solvent is advanced in 2011, volume 30, stage 7; a simulation research computer for refining high-purity methylal by DMF extraction and rectification and an application chemistry No. 29, No. 11 of 2012 report a research for preparing high-purity methylal by using DMF as an extractant; CN102627536B discloses an intermittent extraction, rectification and separation method of a methylal-methanol azeotropic mixture, which adopts a process method for preparing high-purity methylal by using a mixture of polyhydric alcohols such as ethylene glycol, glycerol and the like as an extracting agent; liu hong faithful, etc. continuous extraction, catalytic rectification, preparation of high-purity methylal, chemical development of 2012, volume 31, phase 7, preparation of high-purity methylal by using a formaldehyde aqueous solution as an extracting agent, and the like.
In the above published reports, only one impurity (such as methanol) component can be removed by one-time pressure swing distillation, and the pressure swing distillation under different conditions is still required to be adopted for the impurities such as formic acid and methyl formate with a large boiling point difference with methanol, so that the technology of refining methylal is complex. DMF amides, ethylene glycol and the like are used as extracting agents, and because a third material is added, a methylal refining device needs to be designed with an extracting agent recovery system so as to recycle extracted solvents, and the preparation process of high-purity methylal is complex. The aqueous formaldehyde solution not only can be used as a raw material for preparing methylal, but also can be used as an extracting agent to effectively remove methanol in the methylal, the aqueous formaldehyde solution containing the methanol can be directly used as a raw material for synthesizing the methylal to return to a methylal synthesizing system, a solvent recovery system is omitted, and the process is simple, so that the process for refining the methylal by using the aqueous formaldehyde solution as the extracting agent is a process which is preferentially adopted in the industry at present.
However, both the polyhydric alcohol and the aqueous formaldehyde solution are effective in removing methanol, but are not effective in eluting and extracting formic acid and methyl formate. The utility model discloses a large amount of experiments discover, add a certain amount of alkali (like sodium hydroxide) in formalin can very effectually desorption formic acid and methyl formate in the methylal simultaneously, do not influence the elution effect to methanol at all moreover. The eluted formaldehyde water solution can still be directly used as a raw material for methylal synthesis to enter a methylal synthesis system. The salt (sodium formate) in the aqueous formaldehyde solution as the extractant of the utility model can be added in addition, and can also be produced by the reaction of formic acid and sodium hydroxide, but the protection scope of the utility model is not affected.
Disclosure of Invention
The utility model aims to solve the technical problem that to exist among the prior art not enough, and provide a device of preparation high purity methylal of extraction and rectification synchronous operation, during extractant and methylal raw materials directly entered into the rectifying column, thereby extraction and rectification go on the impurity in the desorption methylal raw materials in step. The utility model takes the formaldehyde aqueous solution containing alkali and salt as the extractant to simultaneously remove impurities such as methanol, formic acid, methyl formate and the like in the methylal to prepare the high-purity methylal, and the prepared methylal has the content of more than 99.95 percent by weight.
In order to achieve the above purpose, the utility model adopts the following technical scheme:
the utility model provides a device of extraction and rectification synchronous operation's preparation high purity methylal, the main part is the rectifying column, and extraction agent and methylal raw materials directly enter into the rectifying column, thereby extract and the impurity in the rectification carries out desorption methylal raw materials in step, its characterized in that:
rectifying column, the top is equipped with extractant import, well below is equipped with raw materials methylal import in the tower wall, and the top of opposite side tower wall is equipped with the backward flow mouth, the top of the tower is equipped with discharge gate I, the tower cauldron is equipped with discharge gate II, wherein: the extractant inlet is connected with a device capable of providing an extractant; the raw material methylal inlet is connected with a device capable of providing the raw material methylal; the discharge port I is connected with a condenser, the outlet of the condenser is divided into two paths, one path is connected with a reflux port, and the other path is connected with a device for collecting high-purity methylal; and the discharge port II is connected with a device for collecting tower kettle liquid.
In the above technical scheme, the rectifying tower is provided with a reboiler at the tower bottom.
In the technical scheme, the raw material methylal enters the rectifying tower from the raw material methylal inlet at the lower part in the tower wall, the extracting agent enters the rectifying tower from the extracting agent inlet at the upper part in the tower wall, the extracting agent and the raw material methylal are in reverse contact, and extraction and rectification can be synchronously carried out.
The utility model discloses the application method of device does: raw material methylal enters the rectifying tower from a raw material methylal inlet at the lower part in the tower wall, an extracting agent enters the rectifying tower from an extracting agent inlet at the upper part in the tower wall, the extracting agent and the raw material methylal are in reverse contact, and extraction and rectification can be synchronously carried out; tower bottom liquid is obtained from a tower bottom of the rectifying tower and is used as a raw material for preparing methylal; and high-purity methylal is obtained at the tower top, after the high-purity methylal is condensed by a condenser, one part of the high-purity methylal is refluxed, and the other part of the high-purity methylal is taken as a high-purity methylal product and is extracted.
The utility model discloses technical scheme's advantage lies in: the utility model discloses a device of preparation high purity methylal has not only got rid of the methyl alcohol in the methylal effectively, has taken off impurity such as formic acid, methyl formate, water in the methylal moreover simultaneously. The formaldehyde extract after removing impurities can be reused as raw material for preparing methylal.
Drawings
FIG. 1 is a schematic diagram of the overall structure of the device for preparing high-purity methylal with synchronous operation of extraction and rectification;
wherein: 1 is a rectifying tower, 2 is an extractant inlet, 3 is a raw material methylal inlet, 4 is a reflux opening, 5 is a discharge opening I, 6 is a discharge opening II, 7 is a condenser, and 8 is a reboiler.
Detailed Description
The following detailed description of the embodiments of the present invention, but the present invention is not limited to the following description:
the utility model provides a device of preparation high purity methylal of extraction and rectification synchronous operation, the main part is rectifying column 1, and during extractant and methylal raw materials directly entered into the rectifying column, thereby extraction and rectification go on the impurity in the desorption methylal raw materials in step, as shown in figure 1:
rectifying column, the top is equipped with extractant import 2 in the tower wall, the well below is equipped with raw materials methylal import 3, the top of opposite side tower wall is equipped with backward flow mouth 4, the top of the tower is equipped with discharge gate I5, the tower cauldron is equipped with discharge gate II 6, wherein: the extractant inlet is connected with a device capable of providing an extractant; the raw material methylal inlet is connected with a device capable of providing the raw material methylal; the discharge port I5 is connected with a condenser 7, the outlet of the condenser is divided into two paths, one path is connected with a reflux port, and the other path is connected with a device for collecting high-purity methylal; the discharge port II 6 is connected with a device for collecting tower kettle liquid; the tower kettle of the rectifying tower is provided with a reboiler 8.
The utility model discloses the application method of device does: raw material methylal enters the rectifying tower from a raw material methylal inlet at the lower part in the tower wall, an extracting agent enters the rectifying tower from an extracting agent inlet at the upper part in the tower wall, the extracting agent and the raw material methylal are in reverse contact, and extraction and rectification can be synchronously carried out; tower bottom liquid is obtained from a tower bottom of the rectifying tower and is used as a raw material for preparing methylal; and high-purity methylal is obtained at the tower top, after the high-purity methylal is condensed by a condenser, one part of the high-purity methylal is refluxed, and the other part of the high-purity methylal is taken as a high-purity methylal product and is extracted.
The utility model discloses in, the mass ratio of extractant and methylal raw materials be 0.5 ~ 30: 1, preferably 0.5-20: 1, more preferably 1 to 10: 1.
in the utility model, in the raw material methylal, the content of methylal is 50-95% wt, and the balance is impurity methanol, formic acid, methyl formate, water and the like.
The utility model discloses in, the extractant for the formalin solution that contains alkali, salt, wherein alkali is sodium hydroxide, sodium hydroxide's concentration be 0.1 ~ 30% wt, preferably 0.1 ~ 10% wt, further preferably 0.1 ~ 5% wt.
The utility model discloses in, the extractant for containing alkali, the formalin solution of salt, wherein the salt is sodium formate, the concentration of sodium formate be 0.001 ~ 20% wt, preferably 0.001 ~ 10% wt, further preferably 0.001 ~ 5% wt.
The utility model discloses in, the extractant for containing alkali, the formalin of salt, the concentration of formaldehyde wherein is 1 ~ 50% wt, preferably 5 ~ 37% wt, further preferably 5 ~ 30% wt.
In the utility model, the pressure at the top of the rectifying tower is 0-0.5 MPa (table), preferably 0-0.2 MPa (table); the pressure of the tower kettle is 0-0.5 MPa (table), preferably 0-0.2 MPa (table); the temperature of the tower kettle is controlled to be 70-125 ℃ by a reboiler, and preferably 95-100 ℃; the temperature at the top of the tower is controlled to be 30-55 ℃ by a condenser, and preferably 40-45 ℃; the outlet temperature of the condenser is controlled to be 30-35 ℃, and preferably 32 ℃; the reflux ratio is controlled to be 1.0 to 10, preferably 2.0.
The device of the present invention is described below with reference to specific embodiments:
example 1:
(1) the raw material methylal (hereinafter referred to as raw material) comprises the following components: 50.50% by weight of methylal, 36.75% by weight of methanol, 2.45% by weight of formic acid, 5.35% by weight of methyl formate and 4.95% by weight of water.
(2) The extraction agent (hereinafter referred to as extraction agent) containing alkali and salt formaldehyde aqueous solution comprises the following components: 32.55 percent of formaldehyde, 2.55 percent of sodium hydroxide, 0.50 percent of sodium formate and the balance of water.
(3) Raw material methylal and an extracting agent continuously enter the device shown in figure 1 at the flow rates of 167g/h and 100g/h respectively, the extracting agent enters from the upper part of the tower, the raw material methylal enters from the lower part of the tower,
(4) the temperature of the tower kettle is controlled to be 95-100 ℃ by a reboiler, and the temperature of the tower top is controlled to be 40-45 ℃ by a condenser; controlling the outlet temperature of the condenser to be about 32 ℃; the reflux ratio is controlled to be 2.0; continuously extracting from the tower top and the tower bottom, and stably operating for 10 hours to obtain 835g of refined methylal. The components of the overhead product liquid were measured and are shown in Table 1.
In this example, the purity of the obtained methylal was 99.99%.
Example 2:
(1) the raw material methylal (hereinafter referred to as raw material) comprises the following components: 89.55 wt% of methylal, 7.85 wt% of methanol, 0.35 wt% of formic acid and 2.25 wt% of methyl formate.
(2) The extraction agent (hereinafter referred to as extraction agent) containing alkali and salt formaldehyde aqueous solution comprises the following components: 6.85 percent by weight of formaldehyde, 0.6 percent by weight of sodium hydroxide, 0.15 percent by weight of sodium formate and the balance of water.
(3) Raw material methylal and an extracting agent continuously enter the device shown in figure 1 at the flow rates of 167g/h and 100g/h respectively, the extracting agent enters from the upper part of the tower, the raw material methylal enters from the lower part of the tower,
(4) the temperature of the tower kettle is controlled to be 95-100 ℃ by a reboiler, and the temperature of the tower top is controlled to be 40-45 ℃ by a condenser; controlling the outlet temperature of the condenser to be about 32 ℃; the reflux ratio is controlled to be 2.0; continuously extracting from the tower top and the tower bottom, and stably operating for 10 hours to obtain 1492g of refined methylal. The components of the overhead product liquid were measured and are shown in Table 1.
In this example, the purity of the obtained methylal was 99.97%.
Comparative example:
(1) the composition of the starting methylal (hereinafter referred to as starting material) was the same as in example 1;
(2) the extractant is: aqueous formaldehyde solution, formaldehyde 32.55% wt, water 67.45% wt.
(3) Raw material methylal and an extracting agent continuously enter the device shown in figure 1 at the flow rates of 167g/h and 100g/h respectively, the extracting agent enters from the upper part of the tower, the raw material methylal enters from the lower part of the tower,
(4) the temperature of the tower kettle is controlled to be 95-100 ℃ by a reboiler, and the temperature of the tower top is controlled to be 40-45 ℃ by a condenser; controlling the outlet temperature of the condenser to be about 32 ℃; the reflux ratio is controlled to be 2.0; continuously extracting from the tower top and the tower bottom, and stably operating for 10 hours to obtain 1570g of refined methylal. The components of the overhead product liquid were measured and are shown in Table 1.
In this comparative example, the purity of the obtained methylal was 95.82%.
Table 1: purity of different methylal products
The above examples are merely illustrative of the technical concept and technical features of the present invention, and thus the scope of the present invention is not limited thereto. All equivalent changes and modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.
Claims (3)
1. The utility model provides a device of extraction and rectification synchronous operation's preparation high purity methylal, the main part is rectifying column (1), and during extractant and methylal raw materials directly entered into the rectifying column, thereby extraction and rectification carry out the impurity in the desorption methylal raw materials in step, its characterized in that:
rectifying column, the top is equipped with extractant import (2) in the tower wall, well below is equipped with raw materials methylal import (3), the top of opposite side tower wall is equipped with backward flow mouth (4), the top of the tower is equipped with discharge gate I (5), the tower cauldron is equipped with discharge gate II (6), wherein: the extractant inlet is connected with a device capable of providing an extractant; the raw material methylal inlet is connected with a device capable of providing the raw material methylal; the discharge port I (5) is connected with a condenser (7), the outlet of the condenser is divided into two paths, one path is connected with a reflux port, and the other path is connected with a device for collecting high-purity methylal; and the discharge port II (6) is connected with a device for collecting tower kettle liquid.
2. The apparatus of claim 1, wherein: the rectifying tower is provided with a reboiler (8) at the tower bottom.
3. The apparatus of claim 1, wherein: the raw material methylal enters the rectifying tower from a raw material methylal inlet at the lower part in the tower wall, the extracting agent enters the rectifying tower from an extracting agent inlet at the upper part in the tower wall, the extracting agent and the raw material methylal are in reverse contact, and extraction and rectification can be synchronously carried out.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112979432A (en) * | 2021-03-02 | 2021-06-18 | 凯瑞环保科技股份有限公司 | Device and method for producing DMMn |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112979432A (en) * | 2021-03-02 | 2021-06-18 | 凯瑞环保科技股份有限公司 | Device and method for producing DMMn |
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