CN211946866U - Device for preparing high-purity methylal by step-by-step operation of extraction and rectification - Google Patents
Device for preparing high-purity methylal by step-by-step operation of extraction and rectification Download PDFInfo
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- CN211946866U CN211946866U CN202020321242.1U CN202020321242U CN211946866U CN 211946866 U CN211946866 U CN 211946866U CN 202020321242 U CN202020321242 U CN 202020321242U CN 211946866 U CN211946866 U CN 211946866U
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Abstract
The utility model discloses a device of preparation high purity methylal of extraction and rectification substep operation, including blender and the rectifying column that links to each other with it: the tower wall central authorities of rectifying column are equipped with the feed inlet, and the top of the tower is equipped with discharge gate I, the tower cauldron is equipped with discharge gate II, and tower wall upper portion is equipped with the backward flow mouth: the feed inlet is connected with the outlet of the mixer; 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. The extractant and the methylal raw material enter a mixer for mixed extraction, and then enter a rectifying tower for rectification separation; 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.
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 operates step 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 substep operation, extractant and raw materials methylal separate in getting into the rectifying column after through the extraction in the blender again, thereby extraction and rectification substep go on the impurity in the desorption methylal raw materials. 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:
a device for preparing high-purity methylal by step operation of extraction and rectification comprises a mixer and a rectifying tower connected with the mixer, wherein an extracting agent and raw material methylal are extracted in the mixer and then enter the rectifying tower for separation, and the device is characterized in that:
the mixer, including an inlet and an outlet, wherein: the inlet is connected with a device capable of providing an extracting agent and/or raw material methylal;
rectifying column, tower wall central authorities are equipped with the feed inlet, the top of the tower is equipped with discharge gate I, the tower cauldron is equipped with discharge gate II, tower wall upper portion is equipped with the backward flow mouth, wherein: the feed inlet is connected with the outlet of the mixer; 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.
The utility model discloses the application method of device does: the extractant and the methylal raw material firstly enter a mixer from an inlet for mixed extraction, and then enter a rectifying tower from a feed inlet in the center of the tower wall for rectification separation; 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 showing the overall structure of an apparatus for producing high-purity methylal by stepwise operation of extraction and rectification according to the present invention;
wherein: 1 is a mixer, 11 is an inlet, and 12 is an outlet; 2 is a rectifying tower, 21 is a feed inlet, 22 is a discharge outlet I, 23 is a discharge outlet II, and 24 is a reflux outlet; 3 is a condenser; 4 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 substep operation, including blender 1 and rectifying column 2 that links to each other with it, extractant and raw materials methylal separate in getting into the rectifying column after through the extraction in the blender again, as shown in figure 1:
the mixer comprises an inlet 11 and an outlet 12, wherein: the inlet is connected with a device capable of providing an extracting agent and/or raw material methylal;
rectifying column, tower wall central authorities are equipped with feed inlet 21, the top of the tower is equipped with discharge gate I22, the tower cauldron is equipped with discharge gate II 23, tower wall upper portion is equipped with backward flow mouth 24, wherein: the feed inlet is connected with the outlet of the mixer; the discharge port I is connected with a condenser 3, 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 rectifying tower is provided with a reboiler 4 at the tower bottom.
The utility model discloses the application method of device does: the extractant and the methylal raw material firstly enter a mixer from an inlet for mixed extraction, and then enter a rectifying tower from a feed inlet in the center of the tower wall for rectification separation; 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 temperature and pressure in the mixer do not need to be specially limited, and the mixer can be operated at normal temperature and normal pressure;
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) Continuously feeding raw material methylal into a mixer at the flow rates of 150g/h and 300g/h respectively, fully mixing the materials, and feeding the mixture into a rectifying tower, wherein the temperature of a tower kettle is controlled to be 95-100 ℃ by a reboiler, and the temperature of a tower top is controlled to be 40-45 ℃ by a condenser; the outlet temperature of the condenser is controlled to be about 32 ℃, and 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 750g 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 99.98%.
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) Continuously feeding raw material methylal into a mixer at the flow rates of 150g/h and 300g/h respectively, fully mixing the materials, and feeding the mixture into a rectifying tower, wherein the temperature of a tower kettle is controlled to be 95-100 ℃ by a reboiler, and the temperature of a tower top is controlled to be 40-45 ℃ by a condenser; the outlet temperature of the condenser is controlled to be about 32 ℃, and 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 1337g 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 99.96%.
Comparative example:
(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: 32.55 percent by weight of formaldehyde and the balance of water.
(3) Continuously feeding raw material methylal into a mixer at the flow rates of 150g/h and 300g/h respectively, fully mixing the materials, and feeding the mixture into a rectifying tower, wherein the temperature of a tower kettle is controlled to be 95-100 ℃ by a reboiler, and the temperature of a tower top is controlled to be 40-45 ℃ by a condenser; the outlet temperature of the condenser is controlled to be about 32 ℃, and 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 1402g of refined methylal. The components of the overhead product liquid were measured and are shown in Table 1.
In this comparative example, the methylal purity obtained was 95.57%.
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 (2)
1. The device for preparing high-purity methylal by stepwise operation of extraction and rectification comprises a mixer (1) and a rectifying tower (2) connected with the mixer, wherein an extracting agent and raw material methylal are extracted in the mixer and then enter the rectifying tower for separation, and is characterized in that:
the mixer comprises an inlet (11) and an outlet (12), wherein: the inlet is connected with a device capable of providing an extracting agent and/or raw material methylal;
rectifying column, tower wall central authorities are equipped with feed inlet (21), the top of the tower is equipped with discharge gate I (22), the tower cauldron is equipped with discharge gate II (23), tower wall upper portion is equipped with backward flow mouth (24), wherein: the feed inlet is connected with the outlet of the mixer; the discharge port I is connected with a condenser (3), 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.
2. The apparatus of claim 1, wherein: the rectifying tower is provided with a reboiler (4) at the tower bottom.
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