JP2010241726A - Method and apparatus for producing acetonitrile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for producing a high-concentration acetonitrile solution having little content of water from an aqueous solution of the acetonitrile. <P>SOLUTION: The method for producing the high-concentration and high-purity acetonitrile solution from the aqueous solution of the acetonitrile includes a part or the whole of an evaporation, condensation and separation step of forming vapor containing the acetonitrile by regulating the temperatures of a container storing the aqueous solution of the acetonitrile in the inside, and the aqueous solution of the acetonitrile at a temperature lower than the azeotropic point of an azeotropic mixture of the acetonitrile and the water for the formation of the vapor by vaporizing the solution in the container to form the vapor containing the acetonitrile from the acetonitrile solution, converting the vapor to a liquid by condensing the vapor, and collecting the acetonitrile solution, a cooling and separation step of obtaining the acetonitrile solution by cooling the acetonitrile solution to a temperature lower than the freezing point of the water and higher than the freezing point of the acetonitrile to separate the water, and heating the resultant product to normal temperature, and an adsorption step of bringing the product into contact with a dehydrating adsorbent. The apparatus therefor is also provided. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method and an apparatus for producing a high concentration acetonitrile solution having a low water content from an acetonitrile aqueous solution or an acetonitrile solution having a high water content, and in particular, a high concentration acetonitrile solution from an acetonitrile aqueous solution or acetonitrile solution used and recovered. The present invention relates to a manufacturing method and apparatus.

Acetonitrile (molecular formula: _CH 3 CN; symbol: AN, MeCN) is a kind of flammable organic solvents, has a flash point of boiling point and about 13 ° C. to about 82 ° C.. Mixing with water in any proportion, but a mixture of acetonitrile and water is an azeotrope that azeotropes at 76 ° C at atmospheric pressure with a water content of 16 weight percent. Acetonitrile has been used as a solvent for chemical reactions, particularly as a solvent for synthesis and purification of pharmaceutical intermediates, and as a moving bed solvent in high performance liquid chromatography (HPLC). In recent years, it has also been used as a DNA synthesis, production solvent, catalyst for organic EL material synthesis, and a cleaning solvent for electronic components. For these applications, high-concentration acetonitrile with high purity and low water content is used. There is a need to provide a solution.

  Acetonitrile solutions are divided into several grades depending on the intended use. That is, unpurified or crude acetonitrile solutions, low grade acetonitrile solutions, industrial grade acetonitrile solutions, high performance liquid chromatograph (HPLC) grade acetonitrile solutions, DNA synthesis grade acetonitrile solutions, and ultra high purity acetonitrile solutions are used in the market. Yes.

  An unpurified acetonitrile solution is an acetonitrile solution obtained as a by-product in the production of plastic raw materials. As an example, an acetonitrile solution obtained in the production of acrylonitrile by catalytic ammoxidation of propylene with ammonia and oxygen (Sohio process) is known. A crude acetonitrile solution generally contains up to 50 weight percent acetonitrile and up to 50 weight percent water.

  The low-grade acetonitrile solution contains a spent waste solution in the HPLC method, a spent waste solution in the DNA synthesis process, and a by-product in the production of the plastic raw material. The low grade acetonitrile solution contains 35 to 85 weight percent acetonitrile and less than about 40 weight percent water.

  Technical grade acetonitrile solutions contain at least 99.75 weight percent acetonitrile and about 500 ppm water and are used, for example, in gas chromatography.

  The HPLC grade acetonitrile solution contains at least 99.8 weight percent acetonitrile and may contain more than 100 ppm water. Furthermore, HPLC grade acetonitrile solutions are formed from very high purity acetonitrile with a UV absorption cutoff wavelength of less than 190 nm.

  The DNA synthesis grade acetonitrile solution contains at least 99.9 weight percent acetonitrile and no more than about 50 ppm water, and the ultra-high purity acetonitrile solution contains at least 99.99 weight percent acetonitrile and no more than about 20 ppm water.

  At present, several methods for producing a high-concentration acetonitrile solution having a low water content from an unpurified acetonitrile solution or an industrial grade or higher acetonitrile solution are already known.

  As a method for producing a high-concentration acetonitrile solution from an unpurified acetonitrile solution, one using azeotropic distillation or extractive distillation is known. For example, as a method for producing an HPLC grade acetonitrile solution that can also be used in an HPLC method from an unpurified acetonitrile solution, a method including a plurality of distillation steps including pressure distillation and vacuum distillation under reflux conditions is known. . However, the production volume of unpurified acetonitrile solution is easily affected by the production plan of the plastic raw material. Therefore, in this method, if the production amount of the plastic raw material is extremely reduced, the production amount of acetonitrile is reduced and acetonitrile is insufficient. There is a fear.

  In addition, methods for producing a high-concentration acetonitrile solution having a low water content from an acetonitrile solution of industrial grade or higher include a method of removing organic impurities using an absorbent, a method of removing water using an absorbent, and the like. . This method is generally only effective when starting with a low water content acetonitrile solution.

  Thus, several methods for producing high-concentration acetonitrile solutions including HPLC-grade acetonitrile solutions, DNA synthesis grade acetonitrile solutions, or ultra-high purity acetonitrile solutions from low-grade acetonitrile solutions have been proposed, but are well established. The method is not known.

  The difficulty in developing a method for producing an acetonitrile aqueous solution or a highly concentrated acetonitrile solution from an acetonitrile solution is that a mixture of acetonitrile and water has a moisture content of 16 weight percent at 76 ° C. under atmospheric pressure (ie, 84 wt. Derived from the fact that it is an azeotrope that azeotropes. That is, since the mixture of acetonitrile and water is an azeotropic mixture, it is difficult to obtain a high concentration acetonitrile solution such as HPLC grade acetonitrile solution.

  If the water content of the acetonitrile solution is less than 16 weight percent before applying the distillation method, 5.25 weight percent acetonitrile is lost to 1 percent water in the distillation step, so after all the water has evaporated. A highly concentrated acetonitrile solution with a very low water content can be obtained.

  For this reason, there has been proposed a method of preparing a high-concentration acetonitrile solution from a low-grade acetonitrile solution by preparing an acetonitrile solution having a water content of the acetonitrile solution smaller than 16 weight percent by combining distillation and pervaporation. The pervaporation method is a method of permeation and separation by changing from liquid to gas with a membrane. Even if the mixture is composed of azeotropic components, they are separated from each other if there is a difference in the membrane permeability coefficient between them. Is possible (see Patent Document 1).

A method using pressure swing distillation instead of combining distillation and pervaporation has also been proposed. In this process, an azeotrope of acetonitrile and water and low boiling impurities are distilled under subatmospheric pressure to separate from high boiling impurities, and then acetonitrile is separated from water and low boiling impurities. Distill under atmospheric pressure.
Under pressures below atmospheric pressure, the weight percent of acetonitrile at the azeotropic point increases, for example, the azeotropic point at 300 mmHg is 51 ° C., the azeotropic point at 89.5 percent by weight of acetonitrile, and the azeotropic point at 150 mmHg is 34 ° C. and azeotrope with 93 weight percent acetonitrile. Therefore, it is possible to make the weight percent of acetonitrile in the acetonitrile solution distilled under atmospheric pressure greater than 84 weight percent (see Patent Document 1).

International Publication WO2005 / 044783

  However, in the method using distillation, since the mixture of acetonitrile and water is an azeotropic mixture, it was difficult to obtain an acetonitrile solution of HPLC grade or higher.

  Moreover, in the method using distillation as in the prior art, entrainment may occur and it is difficult to obtain a high-purity acetonitrile solution. Splash entrainment is a phenomenon in which bubbles are generated by the bursting of bubbles when boiling, and for example, acetonitrile solution obtained by condensing vapor containing droplets can be used for analysis by HPLC method. There was no problem.

  In addition, as described above, after preparing an azeotropic mixture of acetonitrile and water containing 84% by weight or more of acetonitrile and then distilling the azeotrope, a method of obtaining a high-concentration acetonitrile solution as the remainder is obtained by the final method. The amount of the high-concentration acetonitrile solution obtained in this way inevitably has to be reduced, and there is a problem that it is difficult to use for industrial purposes.

  As described above, acetonitrile is flammable and has a flash point of about 13 ° C. In order to heat a mixture of acetonitrile and water to 76 ° C., which is an azeotropic point, for distillation, a heat source heated to a higher temperature is necessary near the mixture, and the distillation process was accompanied by danger. .

  Also, an apparatus for efficiently producing a high-concentration acetonitrile solution such as an HPLC grade acetonitrile solution from an acetonitrile aqueous solution or an acetonitrile solution with a low water content, for example, from a low grade acetonitrile solution, more preferably while simultaneously considering the environment. There was no.

  The object of the present invention is to provide a method and an apparatus for producing a high-concentration acetonitrile solution having a low water content from an acetonitrile aqueous solution or an acetonitrile solution, which solves the drawbacks of the above-described conventional apparatus or method.

  In order to achieve the above object, according to one embodiment of the method for producing a highly concentrated acetonitrile solution from an acetonitrile aqueous solution or acetonitrile solution (hereinafter referred to as “acetonitrile stock solution”) according to the present invention, the temperature of the acetonitrile stock solution is adjusted with acetonitrile. Including an evaporation-condensation separation step of producing a vapor containing acetonitrile from the acetonitrile stock solution by adjusting to a temperature lower than the azeotropic point of the water azeotrope and condensing the vapor to recover the first high-concentration acetonitrile solution. It is characterized by.

Here, the “acetonitrile aqueous solution” refers to a liquid containing at least liquid acetonitrile and water and containing 50% by weight or more of water.
The “acetonitrile solution” is a liquid containing at least liquid acetonitrile and water, and contains 50% by weight or more of acetonitrile. An HPLC grade acetonitrile solution is an acetonitrile solution containing 99.8 weight percent or more of acetonitrile. Sometimes referred to as “hydrated acetonitrile solution”.

  The “high concentration acetonitrile solution” is an acetonitrile solution having an acetonitrile concentration higher than the acetonitrile concentration of the originally prepared acetonitrile stock solution, and preferably includes an acetonitrile solution of HPLC grade or higher. In addition, although not specifically mentioned, the term “high concentration acetonitrile solution” implies a high concentration and high purity acetonitrile solution having acetonitrile concentration and acetonitrile purity higher than acetonitrile concentration and acetonitrile purity of the originally prepared acetonitrile stock solution. .

  In addition, the acetonitrile stock solution may be in a homogeneous material system such as a solution, suspension, emulsion, or the like, or in a heterogeneous material state. Specifically, the state after using a liquid medium as an extractant, a cleaning agent, an eluent, a developing agent, an absorbent, etc. can be mentioned. Examples include extraction / separation / purification of crude drugs and the like, elution by column chromatography, regeneration solution of high-performance liquid chromatograph (HPLC) developing solution or acetonitrile solution used for apparatus cleaning, and the like.

  In addition, the acetonitrile stock solution may include a spent waste solution in the HPLC method, a used waste solution in the DNA synthesis process, and a by-product in the production of the plastic raw material, such as a low grade acetonitrile solution.

In order to evaporate the acetonitrile stock solution without causing entrainment and to generate steam, the temperature of the acetonitrile stock solution is preferably lower.
On the other hand, the higher the temperature of the acetonitrile stock solution, the higher the rate at which steam is generated, and the larger the amount of liquid obtained by cooling the steam.
Therefore, it is preferable to change the heating temperature of the acetonitrile stock solution according to the concentration of acetonitrile desired to be obtained in the first high-concentration acetonitrile solution obtained by cooling the steam. Further, it is preferable to automatically adjust the heating temperature of the acetonitrile stock solution.

  “Condensing steam” may be any process that cools, condenses, and converts the steam into a liquid. For example, it can be carried out using a cooling condenser that converts the flux of vapor passing through the interior into a liquid.

  According to this embodiment, in order to evaporate acetonitrile from the acetonitrile stock solution, the temperature of the acetonitrile stock solution is adjusted to a temperature lower than the azeotropic point of the azeotropic mixture of acetonitrile and water, so that the acetonitrile aqueous solution or the acetonitrile solution is not boiled. Steam with a high concentration of acetonitrile can be obtained. Therefore, acetonitrile and water do not azeotrope, and the first high-concentration acetonitrile solution can be produced efficiently and safely by condensing the vapor.

  In addition, since the temperature of the acetonitrile stock solution is evaporated at a temperature lower than the azeotropic point of the azeotropic mixture of acetonitrile and water, even when this embodiment is applied to an aqueous acetonitrile solution having a high water content, droplet entrainment does not occur. . Moreover, since impurities having a boiling point higher than the azeotropic point of the azeotrope contained in the acetonitrile stock solution can be separated in this step, it is possible to produce a first high-concentration acetonitrile solution of high purity and high concentration or higher than HPLC grade. it can. At the same time, the acetonitrile solution can be produced safely.

  According to another embodiment of the method according to the invention, the evaporative condensation separation step is characterized in that a vapor containing acetonitrile is produced from the acetonitrile stock solution under normal pressure or reduced pressure.

  In general, lowering the environmental pressure of the acetonitrile stock solution lowers the azeotropic point and increases the weight percent of acetonitrile. The reason why the azeotropic phenomenon occurs is that the interaction between acetonitrile molecules and water molecules in the aqueous solution containing acetonitrile is relatively strong, so the pressure in the container is adjusted to adjust the environmental pressure of the acetonitrile stock solution. If it is lowered, the acetonitrile concentration of the liquid obtained by evaporating the acetonitrile stock solution and cooling the vapor becomes higher.

  Therefore, according to this embodiment, the first high-concentration acetonitrile solution can be more efficiently produced from the acetonitrile stock solution used and recovered.

  According to another embodiment of the method according to the invention, the evaporative condensation process is carried out in a closed system or a closed circulation system.

  In such a method, the evaporative condensation separation step is carried out in a closed system or a closed circulation system. In general, the pressure in a closed or closed circulatory system can be easily adjusted as compared to the case where it is not. Moreover, in such a method, acetonitrile contained in the gas separated by condensing the vapor | steam produced | generated by evaporating an acetonitrile stock solution is not discarded. Therefore, in addition to being environmentally safe, there is no risk of acetonitrile being released to the outside, and in the case of a closed circulation system, condensation of vapor generated by evaporating the acetonitrile stock solution is insufficient. It is possible to maintain a high recovery rate by refluxing the steam.

  According to another embodiment of the method according to the invention, in the evaporative condensation separation step, a vapor containing acetonitrile is produced by forcing the gas into contact with the acetonitrile stock solution.

  Here, the “gas” is not particularly limited as long as it is inert to the acetonitrile stock solution. More preferably, even if vapor is condensed and converted into an acetonitrile solution, the gaseous state is maintained. Specific examples include air, nitrogen, helium, and argon, but air is preferable from the viewpoint of cost. However, as will be described later, it may contain a gas separated by condensing vapor generated by evaporating the acetonitrile stock solution.

  “Forcible contact” means that the gas-liquid contact is mechanically and artificially changed by changing the gas into an air flow with a pump and blowing the air flow onto the surface of the acetonitrile stock solution or bubbling gas into the acetonitrile stock solution. To do it. By forcing the gas in contact with the acetonitrile stock solution, it is possible to blow away the boundary film portion formed at the interface between the liquid and gas, constantly update the boundary film portion, and promote the generation of vapor.

  According to another embodiment of the method according to the invention, the gas forced to contact the acetonitrile stock solution comprises a gas separated by condensing the vapor generated by evaporating the acetonitrile stock solution. .

  “Gas separated by condensing steam” is a process of condensing steam and remaining steam without being condensed. When the vapor obtained by evaporating the acetonitrile stock solution is condensed, ideally acetonitrile is condensed to become a liquid, so the gas separated by condensing the vapor does not contain acetonitrile, but condenses the vapor. Depending on the performance of the means used, acetonitrile may be included.

  In order for the gas that is forcibly contacted with the aqueous solution to be a gas separated by condensing the vapor generated by evaporating the acetonitrile stock solution, a plurality of evaporation condensation separation steps are prepared. It is possible to use the vapor generated in step (b) in another evaporative condensation separation process, but it is preferable that the evaporative condensation separation process is performed in a closed system. This closed system is preferably a closed circulatory system that satisfies the reflux condition.

In this case, the recovery rate is lower when the pressure in the closed system is high, but the acetonitrile concentration in the liquid obtained by cooling the vapor is higher when the pressure is high. By setting the degree of vacuum in the closed system to an appropriate value, both the recovery rate and the acetonitrile concentration can be improved.

  Moreover, in the gas separated by condensing the vapor | steam produced | generated by evaporating an acetonitrile stock solution, the partial pressure of acetonitrile is very small. Therefore, when this gas is used for the spraying means and is forcibly brought into contact with an aqueous solution containing acetonitrile, it is easy to vaporize acetonitrile.

  The evaporative condensation separation step may be repeated a plurality of times. By performing the evaporative condensation separation process a plurality of times, the recovery rate can be improved.

  According to another embodiment of the method according to the invention, the acetonitrile stock solution or the first high-concentration acetonitrile solution is cooled to a temperature lower than the freezing point temperature of water and higher than the freezing point temperature of acetonitrile to separate the water and to room temperature. It includes a cooling separation step of heating to obtain a second high-concentration acetonitrile solution.

  Preferably, the cooling separation step includes, for example, spraying the acetonitrile solution obtained in the evaporative condensation separation step into a space cooled to −35 ° C. or less, and ice obtained by solidifying water in the acetonitrile solution at room temperature. A step of heating and melting as described above.

  The freezing point of water is 0 ° C., and the freezing point of acetonitrile is −45.7 ° C. Therefore, by cooling the acetonitrile aqueous solution or acetonitrile solution or the liquid obtained in the evaporative condensation separation process to a temperature lower than 0 ° C. to −45.7 ° C. or higher, only water coagulates to become ice, and acetonitrile becomes a liquid. As it remains, water can be separated from the liquid produced by the condensing means.

  In addition, when impurities having a freezing point higher than the freezing point of acetonitrile are contained in the acetonitrile stock solution or the first high-concentration acetonitrile solution, these impurities can be separated from the acetonitrile solution.

  According to another embodiment of the method according to the present invention, an adsorption is obtained in which a stock acetonitrile solution, a first high concentration acetonitrile solution, or a second high concentration acetonitrile solution is contacted with a dehydrated adsorbent to obtain a third high concentration acetonitrile solution. Including a process.

  By this adsorption step, a high concentration and high purity acetonitrile solution can be obtained. This high concentration and high purity acetonitrile solution can be an HPLC grade or higher acetonitrile solution.

  When the adsorption process is performed using a dehydrated adsorbent such as molecular sieves, the liquid that is passed through the dehydrated adsorbent is changed to an acetonitrile solution produced by a condenser or an acetonitrile solution that has passed through a cooler, thereby dehydrating. The consumption of the adsorbent can be reduced.

  Further, the adsorption step can be performed using an absorbent for removing organic impurities as well as a dehydrated adsorbent. In this case, organic impurities in the acetonitrile solution can be removed.

  According to another embodiment of the method according to the invention, the acetonitrile concentration of the acetonitrile stock solution is determined and, as a result, whether or not the evaporative condensation separation step, the cooling separation step or the adsorption step can be carried out, as well as the parameters and implementation when performing The number of times is determined.

  Here, the “parameter” refers to, for example, the environmental temperature of the acetonitrile stock solution, the environmental pressure, the pressure when the gas is forcibly contacted with the aqueous solution, the condensation temperature for converting the vapor into a liquid, etc. In the cooling separation step, the temperature at which the acetonitrile solution is cooled, and in the adsorption step, the flow rate at the time of bringing the acetonitrile solution into contact with the dehydrated adsorbent can be exemplified.

  Moreover, as a method of determining the acetonitrile concentration of the acetonitrile stock solution, for example, a method of measuring specific gravity and obtaining from the measured specific gravity can be exemplified.

  According to such a method, a highly concentrated acetonitrile solution can be produced from an acetonitrile stock solution by an automatically optimized method.

  In order to achieve the above object, according to one embodiment of an apparatus for producing a high-concentration acetonitrile solution from an acetonitrile stock solution according to the present invention, a container containing the acetonitrile stock solution and an acetonitrile stock solution are evaporated. In order to generate steam, the temperature of the acetonitrile stock solution is set to a temperature lower than the azeotropic point of the azeotrope of acetonitrile and water, and the steam transferred from the container is cooled and condensed to be first. And a condensing means for obtaining a high-concentration acetonitrile solution.

  According to another embodiment of the apparatus according to the present invention, the first processing means includes pressure adjusting means for adjusting the pressure in the container to set the environmental pressure of the acetonitrile stock solution to be equal to or lower than normal pressure. .

  According to another embodiment of the apparatus according to the invention, the first processing means comprises transfer means for transferring the gas separated by condensing the vapor generated by evaporating the acetonitrile stock solution to the container. And

  In such an apparatus, in order to adjust the pressure in the container, a closed circulation system can be formed by the container containing the aqueous acetonitrile solution or the acetonitrile solution and the condensing means.

  According to another embodiment of the apparatus according to the invention, the first processing means comprises gas contact means for forcing gas into contact with the acetonitrile stock solution in order to evaporate the acetonitrile stock solution.

  According to another embodiment of the apparatus according to the present invention, in the first processing means, the gas used for the gas contact means includes the gas separated by condensing the vapor generated by evaporating the acetonitrile stock solution. It is characterized by that.

  Here, the “gas separated by condensing the vapor” is a vapor that has been condensed without being condensed, that is, vapor that has passed through the condensing means.

  Therefore, in the embodiment of the apparatus according to the present invention, the evaporative condensation separation step can be performed by the components of the first processing means including the container, the temperature adjusting means, and the condensing means.

  This evaporative condensation separation step by the first processing means may be repeated a plurality of times. By performing this evaporative condensation separation step a plurality of times, the recovery rate can be improved.

  According to another embodiment of the apparatus according to the invention, the first highly concentrated acetonitrile solution is cooled to a temperature below the freezing point temperature of water and above the freezing point temperature of acetonitrile to separate the water and then heated to room temperature. It includes a second processing means having a cooling means for obtaining a second high-concentration acetonitrile solution.

  In an embodiment of the device according to the invention, the cooling separation step can be performed by the second processing means.

  The cooling means includes means for spraying the acetonitrile solution obtained in the evaporative condensation separation step into a space cooled to a temperature lower than the freezing point temperature of water and higher than the freezing point temperature of acetonitrile, and in the cooled acetonitrile solution and acetonitrile solution And a step of heating and melting ice obtained by coagulation of water at room temperature or higher.

  According to another embodiment of the apparatus according to the present invention, the dehydration adsorbent is brought into contact with an acetonitrile stock solution, a first high concentration acetonitrile solution, or a second high concentration acetonitrile solution to obtain a third high concentration acetonitrile solution. It includes a third processing means having an adsorbing means.

  When the dehydration adsorption means is made of dehydrated adsorbent such as activated alumina, activated bauxite, activated carbon, molecular sieve, or diatomaceous earth, the liquid that passes through the dehydrated adsorbent passes through the liquid produced by the condenser or the cooler. By using the liquid, consumption of the dehydrated adsorbent can be reduced.

  In the embodiment of the apparatus according to the present invention, the adsorption process can be performed by the third processing means.

  The apparatus according to the invention preferably comprises a first processing means, a second processing means and a third processing means. According to such an apparatus, since distillation is not used, the occurrence of entrainment of droplets can be prevented, and moisture can be removed stepwise from a dilute aqueous acetonitrile solution to produce a HPLC grade or higher acetonitrile solution. Further, for example, since a high concentration acetonitrile solution can be produced from an acetonitrile aqueous solution or acetonitrile solution used in the analysis by the HPLC method, the acetonitrile solution can be reused in consideration of the environment. Furthermore, since three different types of processing means can be automatically operated and increased in size as a system, it is possible to efficiently recover, purify, and reuse the acetonitrile solution that has been disposed of after use. Of course, the apparatus according to the present invention need not include all of the first processing means, the second processing means, and the third processing means. A plurality of processing means may be provided. For example, the first processing means may be repeated a plurality of times, or the first processing means and the second processing means may be combined and automatically repeated.

  Moreover, according to another embodiment of the apparatus according to the present invention, one or more concentration determination means for determining the acetonitrile concentration of the acetonitrile stock solution, and the evaporation condensation separation step based on the acetonitrile concentration determined by the concentration determination means, And a control means for determining whether or not the cooling separation step or the adsorption step can be performed, and parameters and the number of times of execution.

  According to such an apparatus, an acetonitrile solution can be produced from an aqueous solution containing acetonitrile by an automatically optimized method.

It is the schematic of the high concentration acetonitrile manufacturing apparatus according to this invention. It is a block diagram of the controller shown in FIG. It is a figure which shows the flowchart in the high concentration acetonitrile manufacturing method according to this invention. It is a figure which shows the influence of the warm bath temperature on the density | concentration and recovery rate of acetonitrile which are produced when manufacturing a high concentration acetonitrile solution from the aqueous solution containing acetonitrile using the high concentration acetonitrile manufacturing apparatus and method according to this invention. It is a figure which shows the influence of the pressure of a closed system with respect to the density | concentration and recovery rate of acetonitrile which are manufactured when manufacturing a high concentration acetonitrile solution from the aqueous solution containing acetonitrile using the high concentration acetonitrile manufacturing apparatus and method according to this invention. When producing a high concentration acetonitrile solution from an aqueous solution containing acetonitrile using the high concentration acetonitrile production apparatus and method according to the present invention, the concentration of acetonitrile in the aqueous solution containing acetonitrile as a stock solution with respect to the concentration and recovery rate of acetonitrile produced. It is a figure which shows the influence of a density | concentration.

  An embodiment of an apparatus and method for producing a high concentration acetonitrile solution from an acetonitrile aqueous solution or acetonitrile solution (hereinafter referred to as “acetonitrile stock solution”) according to the present invention will be described with reference to FIGS.

(General description of embodiment)
A high concentration acetonitrile production apparatus 10 according to the present embodiment will be described with reference to FIGS. FIG. 1 is a block diagram of an apparatus for producing high-concentration acetonitrile according to the present invention. FIG. 2 is a block diagram of the controller shown in FIG.

  The high-concentration acetonitrile production apparatus 10 includes, as a first processing means, a container 102 containing an acetonitrile stock solution, a heating unit 106 constituting a temperature adjustment means, a cooling condenser 110 constituting a condensation means, and a dual pump constituting a pressure adjustment means. 132, a pump 112 and conduits 122, 117 functioning as a transfer means constituting a gas contact means, and a receiver 128.

  The high-concentration acetonitrile production apparatus 10 includes a water freezing removal apparatus 216 and receivers 222 and 224 as second processing means.

  Moreover, the high concentration acetonitrile manufacturing apparatus 10 contains the adsorption tower 310 as a 3rd process means.

Therefore, in this embodiment,
(I) In order to evaporate the acetonitrile stock solution stored in the container and generate steam, the temperature of the acetonitrile stock solution is preferably set to 50 ° C. or less, and the steam transferred from the container is cooled. In order to evaporate the acetonitrile stock solution First treatment means including gas contact means 112, 122, 117 for forcing the gas into contact with the acetonitrile stock solution;
(Ii) Cooling to obtain an acetonitrile solution by spraying the acetonitrile solution obtained by the condensing means into a space preferably cooled to −35 ° C. or less, solidifying the water in the acetonitrile solution to separate the water, and then heating to room temperature Second processing means including means 216;
(Iii) A third adsorption unit 310 including a columnar adsorption tower 310 packed with an adsorbent that removes a trace amount of water in the acetonitrile solution obtained by the second processing means by passing through the inside thereof to obtain a high concentration acetonitrile solution. Processing means;
An apparatus for producing a high-concentration acetonitrile solution from an acetonitrile stock solution containing the same and a method for producing a high-concentration acetonitrile solution using this apparatus are provided.

(First processing means)
In the acetonitrile recovery and purification apparatus 10, the internal space of the container 102, the conduit 120 through which the vapor evaporated in the container 102 passes, the cooling condenser 110 that condenses the steam supplied from the conduit 120, and the gas discharged from the cooling condenser 110 A closed circulation system is constituted by a conduit 122 including the diaphragm pump 112 through which the gas passes and a conduit 117 returning the gas output from the diaphragm pump 112 to the internal space of the container 102. That is, the internal space of the container 102 and the inlet of the cooling condenser 110 are connected by the conduit 120, and the outlet of the cooling condenser 110 is connected to the internal space of the container 102 via the conduit 122 including the pump 112 that constitutes the transfer means.

  A container 102 containing an acetonitrile aqueous solution or acetonitrile solution is immersed in the liquid contained in the container 104. The liquid in the container 104 functions as a bath (bath) for the container 102 and the aqueous solution containing acetonitrile in the container 102. The temperature of the liquid in the container 104 is adjusted by the heating unit 106.

  The temperature of the liquid in the container 104 is measured by a thermometer 116. Although not shown, the thermometer 116 is electrically connected to the controller and sends information about the temperature of the liquid in the container 104 to the controller 500. Information sent to the controller 500 is used to control the heater 106. The controller 500 will be described in detail later.

  The heating unit 106 is electrically connected to the controller 500 and can be operated by an electrical signal from the controller.

  The concentration of the acetonitrile stock solution stored in the container 102 is measured by the concentration sensor 118. The concentration sensor 118 may be of any type as long as it can determine the acetonitrile concentration in an aqueous solution containing acetonitrile, but a sensor that measures the specific gravity and determines the concentration from the measured specific gravity. It can be illustrated.

  Although not shown, the concentration sensor 118 is electrically connected to the controller 500, and information on the acetonitrile concentration determined by the concentration sensor 118 is sent to the controller 500, and the heater 106, which will be described later. Used to control the exhaust pump 132.

  In order to evaporate the acetonitrile stock solution accommodated in the container 102 without causing entrainment of droplets to generate steam, the temperature of the acetonitrile stock solution is preferably low. More preferably, the temperature is 20 to 40 ° C. For example, when vapor is generated by evaporating at 30 ° C., the liquid obtained by cooling the vapor becomes an acetonitrile solution having an acetonitrile concentration of 82.3 weight percent. However, when vapor is generated by evaporation at 50 ° C., the acetonitrile concentration in the acetonitrile solution obtained by cooling the vapor decreases to 63.9 weight percent.

  On the other hand, the higher the temperature of the solution stored in the container 102, the higher the rate at which the vapor is generated, so the amount of liquid obtained by cooling the vapor increases.

  Therefore, the operation of the heating unit 106 is preferably determined by the acetonitrile concentration of the solution contained in the container 102 determined by the concentration sensor 116. For example, in order for the water-containing acetonitrile solution obtained by cooling the steam to have an acetonitrile concentration of about 75 to 85 weight percent, the temperature of the aqueous solution containing acetonitrile is preferably 10 to 40 ° C. in order to generate steam. . Moreover, in order for the water-containing acetonitrile solution obtained by cooling the vapor to have an acetonitrile concentration of about 40 to 60 weight percent, the temperature of the aqueous solution is preferably 45 to 65 ° C. Of course, it is also possible to operate the exhaust pump 132 in conjunction with the operation of the heating unit 106 to perform efficient evaporation.

  An exhaust pump 132 is provided in a part of the closed circulation system. In the present embodiment, the exhaust pump 132 is connected to a conduit branched from the conduit 122 that leads to the cooling condenser 110. The exhaust pump 132 can control the pressure in the closed circulation system. This pressure determines the environmental pressure of the solution contained in the container 102.

  The exhaust pump 132 is electrically connected to the controller 500 and can be operated by an electrical signal from the controller 500. By operating the exhaust pump 132, the aqueous solution containing acetonitrile accommodated in the container 102 can be evaporated under an arbitrary pressure. Further, in order to shorten the evaporation processing time, the exhaust pump 132 can be intermittently operated to change the pressure in the closed circulation system with time.

  The temperature of the liquid contained in the container 104 is also called bath temperature, and is desirably set to be lower than the boiling point of the azeotropic mixture of water and acetonitrile, that is, lower than the azeotropic point. It is good to keep 5-20 degreeC lower than the boiling point of a boiling mixture. Since the boiling point of acetonitrile is about 76 ° C., the temperature of the solution in the container 102 is preferably about 56 to 71 ° C. By setting the bath temperature in this way, the temperature of the aqueous solution containing acetonitrile is also substantially equal to the bath temperature, and the aqueous solution containing acetonitrile does not boil, and the vapor containing acetonitrile and free of splashes is generated from the aqueous solution containing acetonitrile. Generated.

  The steam generated inside the container 102 is supplied to the cooling condenser 110 through the conduit 120. The vapor introduced into the cooling condenser is cooled and condensed at a temperature of 10 to −45 ° C., preferably −10 to −30 ° C. to produce an acetonitrile solution.

  The cooling condenser 110 is connected to the receivers 128 and 130 via the conduit 108, and specifically, connected to the receiver 128 via the valve 124 and to the receiver 130 via the valve 126.

  The cooling capacitor 110 is electrically connected to the controller 500 and can be operated by an electrical signal from the controller.

  The acetonitrile solution generated by the cooling condenser 110 is stored in the receiver 128 or 130. The receivers 128 and 130 are alternately used in the continuous operation of the acetonitrile recovery and purification apparatus 10.

  The conduit 122 is connected to the conduit 117, and the distal end of the conduit 117 is disposed inside the container 102. The tip of the conduit 117 may be disposed at a position higher than the liquid level of the aqueous solution stored in the container 102 or may be positioned in the aqueous solution.

  However, when the gas is forcibly brought into contact with the acetonitrile aqueous solution, a plurality of test tubes are prepared in a sealed box as the gas spraying part, and a solvent is stored in these test tubes and the gas is sprayed. In particular, there are no particular restrictions on the form of spraying, as long as the gas can be forcibly brought into contact with the organic solvent.

  The pump 112 used for gas circulation may be a pump having chemical resistance, and a diaphragm pump made of a fluororesin is preferable. By using the diaphragm pump 112 under conditions where steam mist is not generated, gas can be circulated gently in the circulation system. Further, the gas transfer capability of the diaphragm pump 112 is required to circulate a gas having a volume in the range of 0.1 to 10 times the total internal volume of the container 102 and the cooling condenser 110 in one minute. A diaphragm pump capable of circulating a volume of gas in the range of 0.3 to 3 times per minute is used. For example, if the total volume of the container 102 and the cooling capacitor 110 is 3 to 4 L, a fluororesin diaphragm pump having an exhaust capacity of 1 to 15 L / min can be used. A diaphragm pump with an amount of 3 to 8 L / min may be used.

  The container 102 is, for example, a round bottom flask, and is configured to rotate around its axis. By configuring the container 102 in this way, the temperature of the container 102 can be made uniform, and the aqueous solution accommodated in the container 102 can be evaporated under uniform conditions.

  The temperature adjustment of the aqueous solution containing acetonitrile contained in the rotary container 102 is performed by adjusting the temperature of the liquid placed in the container 104 by the heating unit 106. The vapor generated by evaporation without being heated and boiled is led to the cooling condenser 110 through the conduit 120. A rotating part 114 is provided between the container 102 and the conduit 120. The acetonitrile solution condensed and generated in the cooling condenser 110 is accumulated in the receiver 128 or 130. The receiver 128 or 130 may be a glass round bottom flask.

  When an acetonitrile solution used for high-performance liquid chromatography (HPLC) is used as an acetonitrile stock solution stored in the container 102, particularly an aqueous solution containing acetonitrile, this solution may be an aqueous solution containing high-purity acetonitrile or a water-containing acetonitrile solution. By evaporating the solution at a temperature below the boiling point of the water and acetonitrile azeotrope, it can be separated even if the solution contains impurities having a boiling point higher than that of the water and acetonitrile azeotrope. . Moreover, since entrainment does not occur, the acetonitrile solution obtained in the receivers 128 and 130 by condensing the vapor obtained by evaporating the solution with the cooling condenser 110 can be of high purity.

  The condensation temperature for converting the vapor into a liquid may be any value as long as the vapor becomes a liquid. However, in the case of a vapor generated by evaporating an aqueous solution containing acetonitrile, 10 to -45 ° C is preferable. -10 to -30 ° C is more preferable.

  On the other hand, the gas separated by condensing the vapor generated by evaporating the aqueous solution containing acetonitrile in the cooling condenser 110 passes through the cooling condenser 110. This separated gas is essentially a gas that does not contain acetonitrile, but may contain acetonitrile depending on the performance of the cooling condenser 110. The separated gas that has passed through the cooling condenser 110 passes through the conduits 122 and 117 while being discharged by the pump 112 on the way, and forcibly comes into contact with the acetonitrile stock solution contained in the container 102 from the tip of the conduit 117.

  When the gas is forcibly brought into contact with the solution stored in the container 102, the gas made into an air flow by the pump 112 may be blown onto the surface of the acetonitrile aqueous solution or the acetonitrile solution, or may be stored in the container 102. May be bubbled into the solution. For example, in the case of bubbling, a countercurrent bubble flow is generated that rises from the bottom to the top inside the liquid level of the solution stored in the container 102. By performing the gas-liquid contact mechanically and artificially in this manner, evaporation can be promoted by forcing the air current to come into contact with the boundary film portion formed at the interface between the solution and the gas and blowing away.

  The acetonitrile concentration of the acetonitrile solution accommodated in the internal spaces of the receivers 128 and 130 is measured by the concentration sensors 202 and 204, respectively. Although not shown, the concentration sensors 202 and 204 are electrically connected to the controller 500, and information on the detected acetonitrile concentration is sent to the controller 500. Depending on the acetonitrile concentration of the acetonitrile solution contained in the internal space of the receivers 128 and 130, the acetonitrile solution in the receivers 128 and 130 may be returned to the container 102 again.

  Further, depending on the acetonitrile concentration of the solution stored in the container 102 measured by the concentration sensor 118, the solution stored in the container 102 may be moved to the receivers 128 and 130 without passing through the cooling capacitor 110. Good.

(Second processing means)
The acetonitrile solution produced by the first processing means and collected in the receivers 128 and 130 has a high purity, but the acetonitrile concentration is approximately 75 weight percent or more. Depending on the purpose of use, it can be used in this state, but a higher concentration acetonitrile solution is often required. In such a case, a high-purity and high-concentration acetonitrile solution having an acetonitrile concentration of approximately 95 weight percent can be obtained by passing through the second processing means.

  The second processing means includes a water freeze removal device 216. The acetonitrile solution accumulated in the receivers 128 and 130 is introduced into the water freeze-removal device 216, and the water is separated by cooling to a temperature lower than 0 ° C. and higher than −45.7 ° C. At that time, although water is taken out as ice, the water freeze-removal device 216 also functions as a means for heating and thawing ice by replacing the refrigerant passing through it with a heat medium.

  Conduits 210 and 212 are connected to the internal spaces of the receivers 128 and 130, respectively. The conduits 210 and 212 are further connected to the internal space of the water freeze-removal device 216 via the conduit 214. A pump 232 whose operation can be controlled by the controller 500 is connected to the conduit 214, and the pump 232 can be controlled by the controller 500. The conduits 210 and 212 are provided with solenoid valves 206 and 208, respectively.

  Further, a vent pipe 236 is provided from the water freeze-removal device 216 to the end of the first processing means on the side opposite to the container 102 side of the conduit 107, that is, the end on the side opposite to the cooling condenser 110 of the conduit 122. Further, a pump 232 is provided in the middle of the vent pipe 236. The interior of the vent tube 236 and the conduits 120, 108, 210 and 214 is kept airtight and constitutes a closed system. The pump 232 can control the pressure in the interior space of the water freeze removal device 216 to create a pressure differential within the closed system consisting of the interior space of the vent tube 236, conduits 120, 108, 210 and 214. Therefore, the acetonitrile solution stored in the receiver 128 or 130 is reduced by reducing the pressure in the internal space of the water freeze-removal device 216 and further opening the solenoid valves 206 and 124 or the solenoid valves 208 and 126 and operating the pump 236. Can be introduced into the water freeze-removal device 216. Although not illustrated, the solenoid valves 206, 208, and 232 are also electrically connected to the controller 500 and can be controlled by the controller 500.

  Specifically, by opening the solenoid valves 206 and 124, closing the 208 and operating the pump 232, a pressure difference is generated inside the closed system composed of the vent pipe 236 and the conduits 120, 108, 210 and 214, and the receiver 128 is operated. The acetonitrile solution stored in is introduced into the water freeze-removal device 216. Further, by closing the solenoid valve 206, opening the solenoid valves 208 and 126, and operating the pump 236, a pressure difference is generated inside the closed system composed of the vent pipe 236 and the conduits 120, 108, 212, and 214, and the receiver 130 The stored acetonitrile solution is introduced into the water freeze-removal device 216.

  The water freeze removal device 216 is further connected to the receiver 222 via conduits 226 and 230. The water freeze removal device 216 is further connected to the receiver 224 via conduits 226 and 228. Conduit 228 includes a solenoid valve 220 that can control the passage of liquid in conduit 228. Similarly, the conduit 230 includes a solenoid valve 218 that can control the passage of liquid in the conduit 230. The receiver 222 or 224 may be a glass round bottom flask.

  The acetonitrile solution that has not condensed in the water freeze-removal device 216 is introduced into the receiver 224 by opening the solenoid valve 220 and closing the solenoid valve 218. When the acetonitrile solution that has not condensed in the water freeze-removal device 216 is accommodated in the receiver 224, the solenoid valve 220 is then closed, the solenoid valve 218 is opened, and the ice frozen in the water freeze-removal device 216 is brought to room temperature. A solution obtained by heating and thawing is introduced into the receiver 222.

  The temperature at which the acetonitrile stock solution or the acetonitrile solution obtained in the evaporative condensation separation step is cooled is preferably −35 ° C. or lower. In this case, water can be reliably separated from the acetonitrile aqueous solution or the acetonitrile solution or the acetonitrile solution obtained in the evaporation condensation separation step.

  The acetonitrile concentration of the acetonitrile solution in the receivers 128 and 130 measured by the concentration sensors 202 and 204 is used for control of the water freeze removal device 216.

  The acetonitrile solution collected in the receiver 224 can be used in the next third treatment step. The receiver 224 is provided with a concentration sensor 302 and can measure the acetonitrile concentration of the acetonitrile solution obtained through the second processing step. Although not shown, the concentration sensor 302 is electrically connected to the controller 500, and information on the measured acetonitrile concentration is sent to the controller 500. Depending on the acetonitrile concentration of the acetonitrile solution stored in the internal space of the receiver 224, a part or all of the acetonitrile solution in the receiver 224 may be returned to the container 102 again. Further, in some cases, it may be returned to the receiver 128 or 130.

(Third processing means)
The acetonitrile solution produced by the second processing means and accumulated in the receiver 224 is highly pure, but the acetonitrile concentration is approximately 95 weight percent or more. Depending on the purpose of use, it can be used in this state, but a higher concentration acetonitrile solution may be required. In such a case, a high purity and high concentration acetonitrile solution with an acetonitrile concentration of 99 weight percent, for example, an acetonitrile solution of HPLC grade or higher can be obtained by passing through the third treatment means.

  The third processing means includes an adsorption tower 310. The adsorption tower 310 is filled with a dehydrated adsorbent, and water contained in the solution passing through the inside of the adsorption tower 310 can be removed. Examples of the dehydrating adsorbent include activated alumina, activated bauxite, activated carbon, molecular sieve, diatomaceous earth, and the like.

  The internal space of the receiver 224 and the adsorption tower 310 are connected by a conduit 308 having a solenoid valve 306. The adsorption tower 310 is electrically connected to the controller 500 and its operation can be controlled by a command from the controller 500. Although not shown, the solenoid valve 306 is electrically connected to the controller 500. The conduit 308 is provided with a pump 312, and the acetonitrile solution accumulated in the receiver 224 is introduced into the adsorption tower 310 by operating the pump 312 with the solenoid valve 220 closed and the solenoid valve 306 opened. The

  The adsorption tower 310 is further connected to the receiver 402 via a conduit 314. The acetonitrile solution obtained by passing through the adsorption tower 310 is accumulated in the receiver 402.

  The acetonitrile concentration of the acetonitrile solution accumulated in the receiver 224 is measured by the concentration sensor 302. Information on the acetonitrile concentration of the acetonitrile solution accumulated in the receiver 224 measured by the concentration sensor 302 may be used to control the electromagnetic valve 306 and the adsorption tower 310.

  The acetonitrile solution dehydrated in the adsorption tower 310 is introduced into the receiver 402 through a conduit 314.

  The adsorption tower 310 may be filled with an absorbent for removing organic impurities as well as a dehydrated adsorbent. Absorbents used to remove organic impurities include activated alumina, activated bauxite, activated carbon, molecular sieve, diatomaceous earth, and the like.

  The material used for the high-concentration acetonitrile manufacturing apparatus 10 is not particularly limited as long as it is a material that is impermeable to gas and liquid and has chemical resistance. Examples of materials include inorganic materials such as carbon materials, glass / enamels, stainless steel, ceramics; polyethylene, polypropylene, tetrafluoroethylene resin, trifluorochloroethylene resin, vinylidene fluoride resin, fluorinated ethylenepropylene resin Organic materials such as perfluoroalkoxy resins, unsaturated polyesters, epoxy resins, vinyl ester resins, furan resins, fluororesins; new metals such as titanium, noble metals such as Pt, Al-Mg alloys, copper alloys (for example, Metal materials such as Cu—Sn alloy, Cu—Zn alloy, Cu—Al alloy, Cu—Ni alloy), Ni alloy (eg, Ni—Cu alloy, Ni—Mo alloy, Ni—Cr alloy); or composite material Or a material coated with a corrosion-resistant material. Glass, fluororesin and stainless steel are preferred.

  Further, the container 102 and the receivers 128, 130, 222, 224, and 402 have been shown to be made of glass, but other materials, for example, instruments made of materials used in the above-described apparatus of the present invention may be used. It is often possible to use an instrument that takes into consideration the operating temperature range, chemical resistance, etc. determined according to the type of solvent used.

  Next, the structure of the controller 500 of FIG. 1 will be described with reference to FIG.

  The controller 500 is configured to function as a microcomputer. That is, the controller 500 includes a central processing unit (CPU) 502, a memory 504, and an input / output interface (I / O IF) 506, which are connected to each other via a bus 512. The memory includes an evaporative separation process control program 506 that controls the operation of the components of the first processing means, a cooling separation process control program 508 that controls the operation of the components of the second processing means, and the third processing means. An adsorption process control program 510 that controls the operation of the components is stored.

  Input / output interface (I / O IF) 506 includes pumps 112, 132, 232, 312, solenoid valves 124, 126, 206, 208, 218, 220, 306, warmer 106, cooling condenser 110, water freezing removal It is connected to the apparatus 216, the adsorption tower 310, and the concentration sensors 118, 202, 204, and 302. By communicating with these, information on the acetonitrile concentration is received from the concentration sensor, and signals necessary for the operation of these elements are received. Or send.

  When the CPU 502 of the controller 500 processes the evaporation separation process control program 506, the temperature of the solution in the container 102 measured by the thermometer 116 and the acetonitrile concentration of the solution in the container 102 measured by the concentration sensor 118 are determined. Then, the temperature of the aqueous solution is indirectly adjusted by controlling the heater 106, the environmental pressure of the aqueous solution, that is, the pressure in the closed circulation system is controlled by controlling the pump 132, or the pump 112 is controlled. Controlling the flow rate at which the separated gas is forced to contact the aqueous solution by condensing the vapor generated by evaporating the aqueous solution containing acetonitrile, and controlling the temperature at which the vapor is cooled in the cooling condenser 110 To open and close the solenoid valves 124 and 126 or to the receivers 128 and 130 measured by the concentration sensors 202 and 204 Depending on the concentration of the volume has been acetonitrile solution, or through again evaporation and condensation separation step in acetonitrile in the receiver 128, 130.

  The CPU 502 processes the cooling separation process control program 508 to control the opening / closing timing of the electromagnetic valves 206 and 208, or to open / close the electromagnetic valves 218 and 220 in conjunction with the cooling and heating operations of the water freeze removal device 216. To control.

  The CPU 502 processes the adsorption process control program 510 to control the opening / closing of the electromagnetic valve 306, the operation of the pump 312, and the concentration sensor 302 and a concentration sensor (not shown) provided in the receiver 402. The acetonitrile in the receiver 402 is returned to the receiver 224 or the acetonitrile solution in the receivers 224 and 402 is returned to the container 102 or the receiver 202 or 204, depending on the concentration of the acetonitrile solution in the receivers 224 and 402 measured in Step 1. In addition, the deterioration of the dehydrated adsorbent contained in the adsorption tower 310 is monitored, and depending on the degree of deterioration, the adsorption process is interrupted.

  Therefore, according to the present embodiment, the temperature of the acetonitrile aqueous solution or acetonitrile solution is adjusted between acetonitrile and water in order to generate a vapor by evaporating the solution in the container and the container containing the acetonitrile aqueous solution or acetonitrile solution therein. Evaporation-condensation separation process in which a vapor containing acetonitrile is generated from an acetonitrile aqueous solution or acetonitrile solution by adjusting to a temperature lower than the azeotropic point of the azeotrope of the mixture, the vapor is condensed and converted into a liquid, and the acetonitrile solution is recovered Including a cooling separation step of cooling to a temperature lower than the freezing point temperature of water and higher than the freezing point temperature of acetonitrile to separate the water and then obtaining an acetonitrile solution, and a part or all of the adsorption step for contacting the dehydrated adsorbent, High concentration from acetonitrile aqueous solution or acetonitrile solution And apparatus for producing high-purity acetonitrile solution is provided.

  Next, the process in the high concentration acetonitrile manufacturing apparatus 10 according to the present embodiment will be described with reference to FIG. The following processing can be automatically controlled by the controller 500.

  In S100, an acetonitrile aqueous solution or an acetonitrile solution is prepared. The acetonitrile aqueous solution prepared in S100 may be, for example, a 30% acetonitrile aqueous solution recovered and used in high performance liquid chromatography analysis.

In S110, the acetonitrile stock solution prepared in S100 is stored in the container 102. The acetonitrile concentration of the acetonitrile stock solution stored in the container 102 is measured by the concentration sensor 118. The container 102 is immersed in the liquid accommodated in the container 104, and the temperature of the liquid is controlled by the heater 106 according to the acetonitrile concentration of the acetonitrile stock solution determined by the concentration sensor 118. The tip of the conduit 117 inserted into the container 102 is fixed at a predetermined position in the container. The tip of the conduit 117 may be disposed in the acetonitrile stock solution or may be disposed at a predetermined height from the surface of the acetonitrile stock solution. After operating the pump 132 for 10 seconds, the pump 132 is temporarily stopped, the pump 112 is operated, and the rotation of the container 102 is started. Then, evaporation of the solution in the container 102 starts and steam is generated. Vapor generated by evaporation arrives at the cooling condenser 110 via the conduit 120, where most of the acetonitrile in the vapor is condensed and liquefied and stored in the receiver 128 or 130 as an acetonitrile solution. The operating state of the cooling capacitor 110 depends on the acetonitrile concentration of the acetonitrile stock solution measured by the concentration sensor 118. On the other hand, the gas separated by condensing the vapor by the cooling condenser 110 is forcibly brought into contact with the solution in the container 102 via the conduits 122 and 117. The flow rate when the gas separated by condensing the vapor comes into contact with the solution in the container 102 depends on the operation state of the pump 112, but the operation of the pump is measured by the concentration sensor 118. It is decided according to. Thus, the process in S110 is performed in a closed circulation system. The pump 112 is operated for approximately 30 minutes, and this step ends. At this time, the acetonitrile concentration of the acetonitrile solution in the receivers 128 and 130 is measured by the concentration sensors 202 and 204. Depending on the acetonitrile concentration obtained by the measurement, the acetonitrile solution in the receivers 128 and / or 130 is put into the container 102. You may return. On the other hand, what remains without evaporating in the container 102 is generally an acetonitrile aqueous solution having an acetonitrile concentration of 1 to 3 weight percent, which is discarded.
Next, it progresses to S120.

In S 120, the acetonitrile solution in the receiver 128 or 130 is moved to the water freeze removing device 216 by controlling the opening and closing of the solenoid valves 206 and 208 and operating the pump 232. The temperature at which the water freeze-removal device 216 cools the acetonitrile solution in the receiver 128 or 130 may depend on the acetonitrile concentration of the acetonitrile solution in the receiver 128 or 130. The acetonitrile solution dehydrated by the water freeze-removal device 216 is accumulated in the receiver 224 by opening the electromagnetic valve 220 and closing the electromagnetic valve 218. When the outflow of the acetonitrile solution is finished, the solenoid valve 220 is closed and the solenoid valve 218 is opened to thaw the ice in the water freeze removal device 216. Thawing is performed by switching the refrigerant flowing through the water freeze-removal device 216 to a heat medium during cooling. As a result, the solution obtained by thawing the ice is distilled and collected in the receiver 222. The solution obtained here can be an aqueous acetonitrile solution and is returned to the container 102 in some cases. The acetonitrile concentration of the aqueous acetonitrile solution stored in the receiver 222 can be, for example, 60 to 70 weight percent.
The concentration sensor 302 measures the acetonitrile concentration of the acetonitrile solution that has been frozen and removed from the receiver 224. Depending on the acetonitrile concentration of the acetonitrile solution contained in the interior space of the receiver 224, a part or all of the acetonitrile solution in the receiver 224 may be returned to the container 102 or returned to the receiver 128 or 130. May be sent to S130. The timing of proceeding to S130 is automatically determined by the controller 500 depending on the operation status of the water freeze removing device 216 and the like.

  In S <b> 130, the acetonitrile solution in the receiver 224 moves to the adsorption tower 310 through the conduit 308 by opening the electromagnetic valve 306 and operating the pump 312. In the adsorption tower 310, the water in the acetonitrile solution is adsorbed by the dehydrated adsorbent to obtain a high concentration acetonitrile solution. The state of the absorption dehydrating agent mounted on the adsorption tower 310 is monitored by the controller 500. Depending on the state, depending on the acetonitrile concentration of the acetonitrile solution in the receiver 224, the process of this step may be interrupted or the adsorption dehydrant may be absorbed. The operator of the apparatus 10 may be warned of the need to replace the absorbent dehydrating agent mounted on the tower 310. The high-concentration acetonitrile solution that has passed through the adsorption tower 310 accumulates in the receiver 402. The acetonitrile concentration of the acetonitrile solution stored in the receiver 402 is measured by a concentration sensor (not shown), and depending on the acetonitrile concentration obtained by the measurement, the acetonitrile solution stored in the receiver 402 is stored in the container 102 or the receivers 128, 130, or You may return to 224.

  According to this embodiment, in order to evaporate an acetonitrile aqueous solution or an acetonitrile solution, the aqueous solution containing acetonitrile is evaporated without boiling under conditions of a pressure equal to or lower than normal pressure and a temperature lower than the boiling point thereof. Therefore, an azeotropic mixture of acetonitrile and water does not azeotrope, and a high-concentration and high-purity acetonitrile solution can be produced by condensing the vapor. Further, the acetonitrile solution can be reused with a high recovery rate.

  Moreover, in this embodiment, even if the acetonitrile aqueous solution or acetonitrile solution in the container 102 contains impurities, an evaporation condensation separation step, a cooling separation step, an adsorption step, or a combination of these two or more is performed. Can remove some or all of the impurities from the aqueous acetonitrile or acetonitrile solution. Therefore, a high concentration and high purity acetonitrile solution can be obtained.

  Moreover, in this embodiment, since operation | movement of the high concentration acetonitrile manufacturing apparatus 10 is automatically controlled by the controller 500, a high concentration and highly purified acetonitrile solution can be obtained without bothering an operator's hand. .

  Hereinafter, the Example which manufactures high concentration acetonitrile from the acetonitrile stock solution by the above-mentioned high concentration acetonitrile manufacturing apparatus 10 is described.

Example 1
In S100, 500 mL of an aqueous solution (acetonitrile stock solution) containing acetonitrile having a recovered acetonitrile concentration of about 30%, which is used in high performance liquid chromatography analysis, is introduced into the flask type 1000 mL container 102. In step S110 shown in FIG. 3, the tip of the conduit 117 is adjusted to a height of 3 cm above the surface of the acetonitrile stock solution. On top of that, 77.3% acetonitrile solution (114 g) was obtained in the receiver 128 by performing S110.

(Example 2)
In the same manner as described in Example 1, 500 mL of an aqueous solution (acetonitrile stock solution) containing acetonitrile having a recovered acetonitrile concentration of about 30%, which is used in high-performance liquid chromatography analysis in S100, is introduced into a flask-type 1000 mL container 102. The bath temperature is kept at 30 ° C., and in step S110 shown in FIG. 3, the tip of the conduit 117 is immersed in the acetonitrile stock solution contained in the container 102 and fixed at a height of 1 cm from the bottom of the container 102. On top of that, 82.3% acetonitrile solution (84.4 g) was obtained in the receiver 128 by performing S110.

(Examples 3 to 5)
In Examples 3 to 5, in the same manner as in Example 2, an acetonitrile aqueous solution (acetonitrile stock solution) having an acetonitrile concentration of 30% was placed in the rotary container 102, and the vapor generated by evaporating the acetonitrile stock solution was used. The gas separated by passing through the cooling condenser 110 and condensing is forcedly brought into contact with the acetonitrile stock solution by spraying means, thereby promoting evaporation, and collecting the condensed and liquefied acetonitrile in the cooling condenser 110 at the receiver 128. Then, a high concentration acetonitrile solution is produced from the acetonitrile stock solution. In S110, the temperature of the heating unit 106 for adjusting the temperature of the rotary container 102 is set to 30 ° C., 40 ° C., and 50 ° C., respectively. Results such as acetonitrile concentration and recovery rate are shown in FIG. When the temperature of the heating bath, that is, the temperature of the liquid contained in the container 104 is increased from 30 ° C. to 50 ° C., the water is actively evaporated and the apparent recovery rate approaches 97%, but the acetonitrile concentration is Decrease to 64%.

(Examples 6 to 8)
In the same manner as in Example 2, acetonitrile concentration and recovery rate obtained by changing the pressure inside the rotary container 102, that is, the environmental pressure of the aqueous solution containing acetonitrile, as a recovery condition using a 30% acetonitrile aqueous solution. The results are shown in FIG. That is, when the degree of vacuum is 6 kilopascals (45 mmHg), both the recovery rate and the concentration of acetonitrile exceed 80%, but when the degree of vacuum is reduced, the recovery rate decreases to 63%, but the concentration of acetonitrile is 90%. Approaching%. Further, when the degree of vacuum is increased, the recovery rate exceeds 86%, but the concentration of acetonitrile decreases to 76%.

(Examples 9 to 12)
FIG. 6 shows changes in the concentration of the acetonitrile solution recovered when the concentration of the acetonitrile aqueous solution was changed to 10%, 30%, 50%, and 70%, respectively, in the same manner as in Example 2. The greater the proportion of acetonitrile contained in the stock solution, the higher the acetonitrile concentration in the purified solution.

Claims (8)

  A method for producing a high-concentration acetonitrile solution from an acetonitrile aqueous solution or an acetonitrile solution (hereinafter referred to as “acetonitrile stock solution”), by adjusting the temperature of the acetonitrile stock solution to a temperature lower than the azeotropic point of the azeotropic mixture of acetonitrile and water. A method comprising an evaporation condensation separation step of generating a vapor containing acetonitrile from an acetonitrile stock solution and condensing the vapor to recover a first high-concentration acetonitrile solution.   The method according to claim 1, wherein in the evaporative condensation separation step, a vapor containing acetonitrile is generated from the acetonitrile stock solution under normal pressure or reduced pressure.   The method according to claim 1 or 2, wherein the evaporative condensation separation step is carried out in a closed system.   The method according to any one of claims 1 to 3, wherein the gas is forcibly contacted with the acetonitrile stock solution in the evaporative condensation separation step.   5. The method according to claim 4, wherein in the evaporative condensation separation step, the gas forcibly brought into contact with the acetonitrile stock solution includes a gas separated by condensing vapor generated by evaporating the acetonitrile stock solution.   Furthermore, the acetonitrile stock solution or the first high-concentration acetonitrile solution is cooled to a temperature lower than the freezing point temperature of water and higher than the freezing point temperature of acetonitrile to separate water, and then heated to room temperature to obtain a second high-concentration acetonitrile solution. The process according to claim 1, comprising a cooling separation step.   Furthermore, the adsorption | suction process which contacts a dehydrated adsorbent with an acetonitrile undiluted | stock solution, a 1st highly concentrated acetonitrile solution, or a 2nd highly concentrated acetonitrile solution includes the adsorption | suction process of obtaining a 3rd highly concentrated acetonitrile solution. the method of.   The acetonitrile concentration of the acetonitrile stock solution is determined, and the feasibility of the evaporative condensation separation step, the cooling separation step or the adsorption step, and the parameters and number of times of execution are determined according to the result. The method according to one item.

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