JPWO2005113133A1 - Cooling microwave chemical reactor - Google Patents

Abstract

Cooling-type microwave that can irradiate microwaves while cooling reactants with circulating refrigerant, and that can irradiate microwaves with high convenience, versatility, and maintainability and high-power microwaves It is an object to provide a chemical reaction apparatus. A chemical reaction device having a cooling part in which a refrigerant circulates inside a hollow structure, wherein the cooling part is made of a microwave-absorbing and permeable material, and a microwave-permeable liquid refrigerant is used as the refrigerant A cooling-type microwave chemical reaction apparatus characterized by:

Description

  The present invention relates to a chemical reaction apparatus that can irradiate microwaves while cooling a reactant, and particularly, cooling that is excellent in simplicity, versatility, maintainability, and capable of irradiating high-power microwaves. The present invention relates to a microwave chemical reaction apparatus.

Conventionally, microwaves have been used in limited applications such as radar and microwave heating sources. However, recent research and development have reported that the chemical reaction system is irradiated with microwaves to improve the reaction rate by 1 to 3 orders of magnitude and exhibit specific steric and regioselective properties. It has become clear that monomers can be regenerated from polymers (polystyrene and the like) with high yield.
It is well known that microwaves have been recognized to promote chemical reactions such as reaction rate improvement and reactions different from conventional heating methods, and these effects are often other than microwave heating effects. Alternatively, it is called a microwave effect, a microwave electric field effect, or a non-thermal effect from the viewpoint of an effect higher than the heating effect. Factors that show these excellent characteristics are (1) internal / non-contact / local / fast heating, (2) formation of local reaction fields, and (3) non-thermal reaction promoting effects.

  Conventional microwave heating chemical reactors have difficulty in temperature control. Therefore, in order to manage and control the reaction temperature and the like, it has been proposed that a metallic device such as a thermocouple is inserted into the reaction vessel so as to be substantially orthogonal to the microwave electric field of the TE mode of the microwave electromagnetic field. (Patent Document 1).

  As a chemical reaction apparatus capable of irradiating microwaves while cooling a reactant with a conventional circulating refrigerant, an object to be cooled is poured into a container as shown in FIG. A circulating system (Non-Patent Document 1), an object to be cooled is poured into a cooling vessel provided separately as shown in FIG. 2, and inserted into a cooling rod into a sealed reaction vessel for cooling. (Non-Patent Document 2).

On the other hand, as shown in FIG. 3, a chemical reaction apparatus that cools the surface of a reaction vessel is used for an object to be cooled that does not require microwave irradiation (Patent Document 2).
Electric heat No. 68 page 60 (1993) Nagakichi Shibata Aust. J. Chem. 1995, 48, 1675 Strauss (CSIRO) JP 2002-79078 A Japanese Patent Application Laid-Open No. 08-117587

  The apparatus described in Patent Document 1 cannot irradiate a large amount of microwaves due to the structure in which cooling is not performed. In other words, when a chemical reaction with reaction heat is performed by a microwave heating method that does not involve cooling, large heat removal cannot be expected, and the risk of uncontrollable reaction runaway (thermal runaway) due to its own reaction heat In order to avoid this, it is necessary to set mild reaction conditions or to control the reaction temperature at the boiling point using the heat of vaporization of the solvent.

  In the case of a chemical reaction apparatus as shown in FIG. 1, the object to be cooled is limited to a liquid, the maintainability when the object to be cooled adheres to the cooling part, the shape of the container for storing the object to be cooled is There are problems such as limitations, cooling capacity not being obtained when the amount of objects to be cooled is small, and poor cooling efficiency.

  In addition, in the case of a chemical reaction apparatus as shown in FIG. 2, the object to be cooled is limited to liquid, the cooling capacity cannot be obtained when the object to be cooled is small, and the convenience and versatility are poor. There was a problem such as.

  Also, in microwave chemical reactors, reactants are directly heated by microwaves, so if they are overheated or if thermal runaway is likely to occur due to self-heating due to the reaction, they are immediately cooled to adjust the temperature. Need to do. It is a problem to be solved by the present invention to have a high cooling capacity in order to perform heating to increase the reaction rate, and to immediately remove the heat when reaction heat more than necessary is generated.

On the other hand, in the cooling device shown in FIG. 3, since the reaction container filled with the refrigerant surrounds the object to be reacted, the refrigerant and the reaction container are heated by the microwave when irradiated with microwaves. It was extremely difficult to control the circulating refrigerant in order to maintain the temperature.
Also, during heating, the temperature is transmitted in the order of heat source → hot metal → reaction kettle → reactants, so there will be a time lag, and even if the heat source is dropped during cooling, the temperature of the hot metal will not decrease immediately, so rapid cooling is not possible. It was difficult.

  Therefore, the present invention provides a chemical reaction apparatus capable of irradiating microwaves while cooling a reactant with a circulating refrigerant, and is excellent in simplicity, versatility, maintainability, and capable of irradiating high-power microwaves. An object is to provide a possible cooled microwave chemical reactor.

  In order to solve the above problems, a cooling type microwave chemical reaction device according to the present invention has a structure in which a contact surface between an object to be reacted and a cooling unit is as large as possible, and the cooling unit has a microwave. By using a configuration that is not affected by irradiation, a large heat removal capability was obtained, and a large amount of microwaves could be irradiated. That is, since a large heat removal capability was obtained, it was possible to prevent thermal runaway of the exothermic reaction without performing temperature control using the heat of vaporization of the solvent under tighter high temperature conditions. In addition, since a large amount of microwave irradiation can be performed, hot spots due to cooling and heating can be increased, so that the microwave effect can be extracted. One of the causes of the microwave effect is considered to be a local high temperature field (local superheating [LSH]). That is, according to the present invention, since it is possible to irradiate higher-power microwaves even at the same bulk control temperature, it is easy to form a non-uniform field, increase the number of LSH, A higher temperature can be expected (see FIG. 13).

That is, the gist of the present invention is the cooling microwave chemical reaction device of the following (1) to (8).
(1) A chemical reaction device having a cooling part in which a refrigerant circulates in a hollow structure, wherein the cooling part is made of a microwave-absorbing and permeable material, and a microwave-permeable liquid as a refrigerant. A cooling-type microwave chemical reaction apparatus characterized by using a refrigerant.
(2) The cooling type microwave chemical reaction device according to (1), wherein the cooling unit has a thermal conductivity lower than that of the contact surface with the object to be cooled.
(3) The cooling microwave chemical reaction device according to (1) or (2), wherein the cooling capacity is adjusted by controlling the temperature and / or flow rate of the circulating refrigerant.
(4) The cooling type microwave chemical reaction device according to any one of (1) to (3), wherein the cooling unit includes a tubular container serving as a reaction container for an object to be cooled.
(5) The cooling type microwave chemical reaction device according to any one of (1) to (3), wherein the cooling section has a sheet shape.
(6) The cooling type microwave chemical reaction device according to any one of (1) to (3), wherein the cooling section has a concave shape, and the concave section serves as a reaction container for an object to be cooled.
(7) The cooling microwave according to any one of (1) to (3), wherein the cooling unit includes a reaction vessel for a detachable object to be cooled and a refrigerant tank that surrounds the reaction vessel. Chemical reactor.
(8) The microwave chemistry according to any one of (1) to (7), wherein the cooling unit is provided in a chamber that reflects microwaves, and microwave irradiation is performed on the entire cooling unit in the chamber. Reactor.

According to the cooling type microwave chemical reaction device according to the present invention, it becomes possible to irradiate a high-power microwave compared with the conventional microwave chemical reaction device.
In addition, since the reaction temperature of the object to be cooled is kept constant by simultaneously performing heating by microwave irradiation and heat removal by the circulating refrigerant, temperature control can be easily performed. That is, it is possible to provide a microwave chemical reaction apparatus that can be heated immediately when it is desired to be heated and can be immediately removed when it is desired to be cooled.

Moreover, it is excellent in versatility in that the structure of the control device is simple and the cooling unit can be formed in various forms.
In the configuration including the container-type refrigerant, since it is not necessary to make the cooling part in a complicated shape in order to obtain the cooling efficiency in a small amount experiment, the cleaning time after the end of the experiment can be shortened, and the maintainability is excellent.

  Moreover, the problem of temperature unevenness in the conventional apparatus can be improved. In particular, in a configuration including a tube-type refrigerant, the problem of temperature unevenness can be solved, and sufficient cooling capacity can be obtained even with a small amount of object to be cooled.

  In a configuration including a plate-type refrigerant, a cooling chemical reaction can be performed while irradiating microwaves even on a solid or gel object to be cooled in the form of a sheet.

  In the configuration in which the reaction vessel is detachable, the reaction vessel can be exchanged without removing the refrigerant circulation device when the experiment is performed with the reaction vessel having the same shape, and the experiment time can be shortened.

1 is a configuration diagram of a conventional cooling-type microwave chemical reaction device 1. FIG. 1 is a configuration diagram of a conventional cooled microwave chemical reaction device 2. FIG. It is a block diagram of the conventional normal cooling type chemical reaction apparatus. It is a schematic diagram of the batch-shaped reaction container concerning this invention. It is a schematic diagram of the tubular reaction container which concerns on this invention. It is a schematic diagram of the serpentine tubular reaction container according to the present invention. It is a schematic diagram of the plate-shaped reaction container concerning this invention. 1 is a configuration diagram of a cooling type microwave chemical reaction device according to Example 1. FIG. It is a graph of the microwave input energy in the conventional microwave chemical reaction apparatus. 2 is a graph of microwave input energy in the microwave chemical reaction device according to Example 1. 6 is a configuration diagram of a microwave chemical reaction device according to Example 2. FIG. 3 is a configuration diagram of a microwave chemical reaction device according to Example 3. FIG. It is a schematic diagram of LSH promotion. It is the schematic diagram which compared the positional relationship of the heat input by a microwave, and the heat removal by a cooling device. 6 is a graph showing the heat removal capability according to Example 4. 6 is a graph showing measurement results of temperature unevenness in a serpentine tubular reaction container according to Example 5.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Reaction container 2 Cooling part 3 Refrigerant 10 To-be-reacted object 12 Cathode-shaped reaction container 13 Cooling tank 14 Refrigerant outlet 15 Cooling tank upper cover 16 Three-necked flask-shaped reaction container upper part 18 Polished glass joint part

  The cooling type microwave chemical reaction device according to the present invention is a chemical reaction device having a cooling part in which a refrigerant circulates inside a hollow structure, and the reaction vessel is made of a material that absorbs and absorbs microwaves. In addition, a microwave permeable liquid refrigerant is used as the refrigerant. Here, since various substances are assumed as the target reaction object, in order to obtain a sufficient cooling effect, it is necessary to use reaction containers having different shapes depending on the characteristics and quantity of each substance. For example, in the case of a high-viscosity liquid or when performing an experiment with a small amount, a batch reaction vessel as shown in FIG. 4 is suitable, and when a large cooling capacity is required or when an experiment is performed in a continuous reaction. For this, a tubular container as shown in FIG. 5 is suitable. In addition, when a large cooling capacity is required or when it is desired to take a long reaction time in a continuous reaction, a serpentine reaction vessel as shown in FIG. 6 is suitable. Further, when the object to be cooled is a sheet-like solid or gel, a plate-like reaction container as shown in FIG. 7 is suitable.

  A problem with the microwave irradiation type chemical reaction apparatus is that it is more expensive than other heating means, but it is necessary for the purpose of microwave irradiation (microwave non-thermal effect, microwave heating characteristics, etc.). The minimum energy may be irradiated with microwaves, and the rest may be covered by another inexpensive heating method. In general chemical reactions, temperature control is often performed at a temperature higher than room temperature. However, when “room temperature <refrigerant temperature <reaction temperature”, the refrigerant acts as a “heating medium” for preheating the raw material. Will have.

  Hereinafter, the details of the present invention will be described with reference to examples, but the present invention is not limited to the examples.

FIG. 8 is a configuration diagram of a cooling type microwave chemical reaction device according to the first embodiment.
As shown in FIG. 8, the cooling type microwave chemical reaction device according to the first embodiment includes an applicator portion 84, a cooling device 94, and a fluorine-based resin tube 95 that connects them. The cooling device 94 includes a liquid tank 92 in which the refrigerant liquid is stored and a pump 93 for sending out the refrigerant liquid. The flow rate of the refrigerant liquid delivered from the pump 93 is automatically adjusted by controlling the solenoid valve 87 by the flow rate control box 89 that is linked to the measuring device 88. Note that the flow rate of the refrigerant liquid can be manually adjusted by the flow rate adjusting valve 86.
The cooling unit 80 has a hollow structure, and is provided with a refrigerant liquid circulation unit 82 for circulating the refrigerant liquid. The cooling unit 80 is made of a glass material that is permeable to microwave absorption, and the refrigerant liquid uses a non-polar oil liquid that is permeable to microwaves. A reaction object 85 is placed in the reaction vessel 81, and the temperature of the reaction object 85 is measured by an optical fiber thermometer 91 inserted in the reaction object and stored in the measuring device 88.

  The reaction vessel 81 is not limited to glass as long as it is made of a microwave permeable material, and preferable materials include fluororesin and ceramic. Further, the refrigerant liquid may be a nonpolar solution.

The applicator section 84 is a chamber that reflects microwaves like a casing of a microwave oven, and exhibits a high heating effect by passing through the microwave-permeable reaction vessel 81. That is, the microwave irradiated from the outside of the applicator part 84 is reflected in the applicator part 84 and heats the reactant while passing through the reaction vessel 81 from the top, bottom, left and right.
FIG. 14 shows the relationship between the conventional reaction vessel and the microwave irradiation position, and the relationship between the reaction vessel and the microwave irradiation position in this example.
The comparative example is a device with a cooler inside. In the configuration in which the refrigerant is in the reactant, for example, when the high-viscosity reactant cannot sufficiently stir, the heat of reaction generated in the irradiation unit cannot be removed by the cooling unit.

  In the case where the reaction vessel (metal jacket pot) also serves as a chamber, if the reaction vessel is damaged due to high pressure, corrosion, etc., an accident will occur immediately. Can act as a safety cover.

Using the cooling microwave chemical reaction apparatus and the non-cooling microwave chemical reaction apparatus according to this example, an experiment was performed to deposit hydroxyapatite on titanium oxide (photocatalyst). Microwave could be irradiated.
FIG. 9 is a graph of microwave input energy in the conventional microwave chemical reaction apparatus, and FIG. 10 is a graph of microwave input energy in the microwave chemical reaction apparatus according to Example 1.
As can be seen from FIGS. 9 and 10, in the uncooled microwave chemical reaction apparatus, in order to keep the reaction temperature at 40 ° C., only microwaves with an average of 30 W could be irradiated. In the wave chemical reaction apparatus, microwave irradiation with an average of 150 W was able to be performed while maintaining the reaction temperature at 40 ° C. when microwave irradiation was performed while circulating a −5 ° C. refrigerant.

  In the cooling type microwave chemical reaction device according to the second embodiment, the cooling unit 2 is disposed in the chamber, and the microwave from the microwave transmitter is passed through the waveguide (waveguide, coaxial cable, etc.) in the chamber. It is a cooling type microwave chemical reaction device of the mode which irradiates. For example, the cooling unit is arranged in a box such as a microwave oven.

As shown in FIG. 11, the cooling unit 2 includes a cooling tank 13 in which the refrigerant 3 circulates and the reaction container 1, and the refrigerant tank 13 is formed by a refrigerant tank upper lid 15 having a reaction container insertion hole and a refrigerant outlet 14 hole. Covered.
In addition, it is also possible to cool the sheet-like reactant by changing the upper lid 15 for the sheet to one without a reaction vessel insertion hole.

  As shown in FIG. 12, the cooling type microwave chemical reaction device according to Example 3 is configured by fitting the three-necked flask-shaped reaction vessel upper portion 16 with the polished glass joint portion 18 provided in the reaction vessel 1 in the configuration of Example 2. It is the composition made to do.

  In the case of an organic reaction or the like, reflux cooling may be performed, or the reaction may be performed in an atmosphere of a rare gas such as nitrogen. When performing such a reaction, the configuration according to this embodiment is suitable.

There are two ways to suppress thermal runaway due to self-heating (reaction heat). One is a method of slowing the reaction rate by lowering the reaction temperature and dispersing the generation of reaction heat, and the other is a method of removing the reaction heat using the heat of vaporization of the solvent. In the former case, since the reaction rate is slow, the risk of generating reaction heat at once can be reduced, but there is a problem that a long-time reaction is required. In the latter case, there are problems that the reaction temperature is determined by the boiling point of the solvent and that extra energy such as heating and vaporization of the solvent is required. Even in natural cooling, a constant heat removal is possible, but the heat removal capability is low and it is difficult to suppress thermal runaway (see FIG. 15).
Therefore, a cooling system using a refrigerant or the like is necessary. However, since the microwave chemical reaction apparatus has a characteristic of immediate heating of microwaves, high heat removal capability and quick response are required.

In this example, the heat removal ability of the apparatus when a batch-type reaction vessel as shown in FIG. 4 was used was measured. FIG. 15 shows the relationship between the control temperature and the refrigerant temperature, and the heat removal capability of the apparatus of this embodiment can be confirmed. The horizontal axis indicates the temperature of the reaction product, and the vertical axis indicates the cooling capacity, and the plots for each refrigerant temperature (0 to 40 ° C.) were compared with those naturally cooled. Although water is used as a model substance, the heat removal ability (cooling ability) does not depend greatly on the substance, so the heat removal ability is almost the same even in actual reactions.
In addition, since the present Example mainly aims to measure the heat removal capability of the apparatus, microwave irradiation is not performed.

  It is known that “reaction temperature” is important as a factor for controlling a chemical reaction. In experiments where tight reaction temperature control is required, it is preferable that there is no temperature variation in the reaction vessel and that the reaction can be controlled at a constant temperature. Although heating unevenness can be minimized by heating the tubular reaction vessel as a whole, there is a problem that temperature unevenness occurs when cooling is performed by natural cooling (FIG. 16). reference).

  In this example, the occurrence of temperature unevenness in the serpentine tube reaction vessel as shown in FIG. 6 was compared between when the refrigerant was circulated and when naturally cooled. The experimental conditions are as follows.

(Experimental conditions)
・ Reactant: Ethylene glycol ・ Refrigerant temperature: 52.0 ℃
・ Refrigerant flow rate: Approximately 4.5L / min
・ Set value of reactant flow rate: 20ml / min
・ Microwave dose: See Fig. 16

The experiment during the circulation of the refrigerant was performed twice under the same conditions assuming that an error occurred. The temperature measurement points were set for every half circumference of the serpentine tube, and 11 points were provided. Irradiate the same amount of microwave as the amount of microwave irradiation at the time of natural cooling at a control temperature of 70 ° C, and adjust the refrigerant temperature so that it becomes 70 ° C at the position of (11), thereby eliminating the temperature unevenness in the tube reaction vessel. Verified.
In addition, since a present Example aims at verifying the temperature nonuniformity by heat input and heat removal, a specific chemical reaction is not accompanied.

  Under the above experimental conditions, when microwave irradiation was performed for each of the refrigerant circulation and natural cooling, it was confirmed that the temperature unevenness was reduced as compared with the natural cooling as shown in FIG. That is, since heating and cooling are performed on the entire tubular flow path, the problem of temperature unevenness during chemical reaction can be solved.

To date, practical technologies using microwaves include industrial heating, pasteurization, sintering and bonding of ceramics, etc. Recently, decomposition of harmful substances, high-efficiency production of organic and inorganic compounds, diagnosis / Application research for treatment, enzyme reaction, bioreactor, etc. is also conducted. In microwave chemical reaction systems, efficient internal heating and selective heating of target molecules are expected to simplify the process, reduce the size of the reactor, or significantly reduce processes and energy consumption without using solvents. In addition to being able to do so, it will be possible to simply synthesize high-performance new materials with non-equilibrium structures and structures.
The present invention can be applied to all techniques that can be effective by microwave irradiation, and is expected to be used particularly in the fields of polymer synthesis, esterification reaction, oxidation reaction and the like.

Claims (8)

A chemical reaction device having a cooling part in which a refrigerant circulates inside a hollow structure,
The cooling type microwave chemical reaction device, wherein the cooling unit is made of a material that absorbs and transmits microwaves, and uses a microwave-permeable liquid refrigerant as a refrigerant.   The cooling type microwave chemical reaction device according to claim 1, wherein the cooling unit has a lower thermal conductivity than the contact surface with respect to the object to be cooled.   The cooling type microwave chemical reaction device according to claim 1 or 2, wherein the cooling capacity is adjusted by controlling the temperature and / or flow rate of the circulating refrigerant.   The cooling type microwave chemical reaction device according to any one of claims 1 to 3, wherein the cooling section includes a tubular container serving as a reaction container for an object to be cooled.   The cooling type microwave chemical reaction device according to any one of claims 1 to 3, wherein the cooling section has a sheet shape.   The cooling type microwave chemical reaction device according to any one of claims 1 to 3, wherein the cooling part has a concave shape, and the concave part serves as a reaction container for an object to be cooled.   The cooling type microwave chemical reaction device according to any one of claims 1 to 3, wherein the cooling section includes a detachable reaction container for an object to be cooled and a refrigerant tank surrounding the outside.   The microwave chemical reaction device according to any one of claims 1 to 7, wherein the cooling unit is provided in a chamber that reflects microwaves, and microwave irradiation is performed on the entire cooling unit in the chamber.