JP5110561B2 - Supercritical carbon dioxide reaction method and apparatus - Google Patents

Description

  The present invention relates to a reaction method in which an organic reaction substrate and a reactant are reacted through a selectively permeable membrane in the presence of a catalyst using carbon dioxide as a medium, and a reaction apparatus thereof. The present invention relates to a new reactor comprising a supported hydrogen-selective mesoporous silica membrane and a reactor having a heterogeneous catalyst and capable of performing a reaction between hydrogen permeated through the membrane and an organic reaction substrate in a supercritical carbon dioxide medium. Is.

  In the present invention, by combining an inorganic porous permselective membrane and a heterogeneous catalyst, a reaction having a high reaction yield and high selectivity can be achieved in a very short time. The present invention also provides an environmentally friendly organic compound synthesizer that is compact and can minimize energy consumption.

  Membrane reactors that use thin film separation technology are a new type of reactor that consists of compact designs. This apparatus has excellent advantages such as minimization of energy consumption during operation and safe reaction. In the last century, there have been a number of major advances in fuel and chemical manufacturing technologies, such as catalysts, heat integration, product purification, and waste purification.

  However, even in this century, there is a need for further improvements in manufacturing processes and catalyst technologies as well as new manufacturing technologies. Under such circumstances, as one of innovative technologies, the membrane reactor has the potential to contribute greatly to making the manufacturing process more compact and minimizing the funds required for its construction.

  The technology related to the membrane reactor improves the reaction rate of the conventional reaction, which is restricted by the equilibrium phenomenon, makes it easy to control the reaction, reduces energy consumption, and further reduces the raw material / It makes it possible to reduce the costs required for product separation. The basic principle of the membrane reactor is to selectively supply them to the reaction zone by utilizing the phenomenon that organic reaction substrates or reagents permeate and diffuse through the membrane. Thereby, in the membrane reaction technique, it is possible to prevent an undesirable reaction and to prevent the adsorption of the catalyst poison to the catalyst.

On the other hand, by using supercritical carbon dioxide (scCO ₂ ) as a reaction medium, it is possible to construct an epoch-making reaction process using characteristics unique to high-density gas. The most important property of supercritical carbon dioxide is that supercritical carbon dioxide can completely dissolve other gaseous substances. Most liquids can only dissolve a limited amount of gaseous substances, whereas supercritical carbon dioxide dissolves other gaseous substances such as hydrogen gas and oxygen gas in high concentrations, It exhibits the property of being able to form a single phase with an organic reaction substrate.

  Therefore, the reaction rate in supercritical carbon dioxide is extremely high compared to the reaction in solution. This is a particularly important factor in reactions that require a large amount of mass transfer. Furthermore, in the supercritical state, the partial molar volume being negative can be used to control the reaction rate constant. Combining this property with the high mass transfer rates found in supercritical carbon dioxide, supercritical carbon dioxide-based reactions provide many advantages in catalytic reactions.

  Until now, homogeneous catalytic reactions have been mainly used for membrane reactors using supercritical carbon dioxide. Most of the existing technologies utilize membranes for separation of organic reaction substrates and reaction products. For this reason, separation membranes having a small pore size and usable in supercritical carbon dioxide have been developed. It was. These nano-separation membranes exhibit a separating action depending on the difference in molecular size between simple organic compound molecules and metal complexes, allowing the solvent and reaction product molecules to pass through, but having a large molecular catalyst. Hold without passing.

  Thus, supercritical carbon dioxide and the reaction product are transported through the membrane, but the catalyst remains in the reactor. However, this method has several drawbacks, such as low solubility of the catalyst in supercritical carbon dioxide. In order to increase the solubility of the catalyst in supercritical carbon dioxide, it is necessary to bind an expensive ligand such as a perfluoroalkyl group having a low cohesive energy density to the catalyst. In order to solve these problems, the present invention has developed a reactor suitable for a new membrane reaction using supercritical carbon dioxide using a heterogeneous catalyst.

  Conventionally, an organic film has been mainly used in a reaction apparatus using carbon dioxide as a medium. However, the use of an organic film in a carbon dioxide medium presents several drawbacks in terms of swelling and stability. Therefore, many different types of inorganic membranes have been developed and can be used in reactors using carbon dioxide.

  These inorganic films not only exhibit the physical and chemical characteristics of the organic film, but only partially, and are excellent in structural stability without problems with swelling and compactness. Furthermore, the inorganic silica film has a property of transmitting hydrogen more highly than carbon dioxide. However, the present situation is that sufficient research has not been made to apply the inorganic membrane to a reactor using carbon dioxide as a medium.

  Examples of conventional techniques for synthesizing a compound by heterogeneous catalytic reaction using supercritical carbon dioxide as a medium include, for example, a compound containing a carbon-carbon double bond or carbon-carbon triple bond, hydrogen, and carbon monoxide. Has been reported to be subjected to a hydrocarbonylation reaction in supercritical carbon dioxide in the presence of a Group VIII transition metal catalyst precursor and a phosphite ligand (see Patent Document 1).

  Also, supercritical carbon dioxide, subcritical carbon dioxide or carbon dioxide is used as a reaction medium, and an olefinic hydrocarbon is oxidized with oxygen, air or a gas containing oxygen using an inorganic oxide and / or a noble metal as a catalyst. Thus, there has been reported an olefinic hydrocarbon oxidation method for producing a carbonyl compound, an epoxide, etc. and improving the conversion rate and the yield of the reaction product (see Patent Document 2).

  Also, in a method for selective hydrogenation of an aliphatic or aromatic substrate under supercritical or near critical conditions, a heterogeneous catalyst is used in a continuous flow reactor in which the hydrogenation contains a supercritical or near critical reaction medium. A supercritical hydrogenation process has been reported that is carried out and the product production selectivity is achieved by changing one or more of temperature, pressure, catalyst and flow rate (see Patent Document 3). However, there is no conventional example using a membrane reactor in the reaction of synthesizing a compound in the presence of a heterogeneous catalyst using supercritical carbon dioxide as a medium.

JP 2000-53606 A JP-A-2005-170856 Special table 2000-508653 gazette

  In such a situation, in view of the above-mentioned prior art, the present inventors have made a synthesis technique of an organic compound capable of efficiently synthesizing a product by reacting an organic reaction substrate with a reactant. As a result of intensive research aimed at development, carbon dioxide is used as a medium, and the reaction is carried out in a short time and in a high yield by reacting the organic reaction substrate and the reactant through the permselective membrane. As a result, the inventors have found a new synthesis technique that enables the above-mentioned and further researched to complete the present invention.

  The present invention relates to a method for synthesizing an organic compound capable of performing a reaction in a short time and in a high yield by reacting an organic reaction substrate and a reagent through a permselective membrane using carbon dioxide as a medium, and a method thereof. Providing an apparatus, and the present invention is a membrane reactor operable in a supercritical carbon dioxide medium, capable of achieving a high reaction rate under mild reaction conditions, The present invention also provides a reaction apparatus capable of allowing a reaction excellent in selectivity of a target compound to proceed in a short time, and the present invention provides an organic reaction substrate and a reactive gas such as hydrogen and oxygen. It is an object of the present invention to provide a reaction method and apparatus capable of performing efficient oxidation, reduction, hydrogenation reaction, and the like.

  The present invention also provides a novel reaction apparatus for performing a reaction in a supercritical carbon dioxide medium using an inorganic permselective membrane having no problem in swelling and stability in the presence of a heterogeneous catalyst. In addition, the present invention provides a membrane reaction apparatus using a mesoporous silica film supported on an alumina surface, and further, the present invention can minimize costs related to the catalyst and energy consumption. An object is to provide an environmentally friendly reactor.

The present invention for solving the above-described problems comprises the following technical means.
(1) as a medium of carbon dioxide in the presence of a catalyst, it met the reactor is reacted with the organic reaction substrate reagent,
A flow path of carbon dioxide containing a reactive agent (first flow path), a flow path of carbon dioxide containing an organic reaction substrate (second flow path), and a reactive agent permselective membrane supported by a porous member ; The first flow channel and the second flow channel form an inner tube or an outer tube having a multi-tube structure, and the reactant in the first channel is selectively transmitted to another channel through the reactant selective permeation membrane. It is arranged so as to be permeable, and has a structure in which a catalyst exists in a reaction zone in which a reaction agent that has passed through the organic reaction substrate in the second flow path and the reagent selective permeation membrane reacts,
Carbon dioxide, the pressure range of 4～20MPa, and a carbon dioxide temperature ranging from room temperature to 100 ° C., the reactor in which the reactants, characterized in that hydrogen or oxygen reactive gas.
(2) The reaction apparatus according to (1), wherein the catalyst is a heterogeneous catalyst.
(3) Reagent selective permeation membrane is silica membrane, mesoporous silica membrane, Pd membrane, bentonite membrane, alumina membrane, Pd ion exchange membrane, copper-LaNi ₅ membrane, aluminosilicate membrane, zeolite membrane, palladium alloy membrane, perovskite membrane Or the reactor according to (1) above, which is a CeO ₂ / ZrO ₂ -coated TiO ₂ film.
(4) The reaction apparatus according to any one of (1) to (3), wherein the carbon dioxide is carbon dioxide in a subcritical or supercritical state.
(5) Using the reactor according to any one of (1) to (3) above, using a carbon dioxide in a pressure range of 4 to 20 MPa and a temperature range of room temperature to 100 ° C. as a medium, A reaction method of reacting an organic reaction substrate with a reactant in the presence of
A flow path of carbon dioxide containing a reactive agent (first flow path), a flow path of carbon dioxide containing an organic reaction substrate (second flow path), and a reactive agent permselective membrane supported by a porous member; The first flow channel and the second flow channel form an inner tube or an outer tube having a multi-tube structure, and the reactant in the first channel is selectively transmitted to another channel through the reactant selective permeation membrane. In a reaction apparatus having a structure in which a catalyst is present in a reaction zone that is disposed so as to be permeable and in which a reaction agent that has passed through an organic reaction substrate in a second flow path and a reaction agent permeation membrane has reacted. Using a reactive gas such as hydrogen or oxygen as the reactant, the reactant contained in the carbon dioxide medium introduced through the first flow path is selectively permeated through the reactant selective permeation membrane to react the reaction zone. And the reaction agent permeated in the reaction zone and the organic reaction substrate introduced through the second flow path. The reaction wherein the reacting in the presence of the catalyst.
(6) The reaction method according to (5), wherein the organic reaction substrate and the reactant are reacted using carbon dioxide in a subcritical or supercritical state as a medium.

Next, the present invention will be described in more detail.
The present invention relates to a reaction apparatus for reacting an organic reaction substrate with a reactant in the presence of a catalyst using carbon dioxide as a medium, the channel for carbon dioxide containing the reactant (first channel), the organic reaction substrate. A carbon dioxide flow path (second flow path) including a reactive agent permselective membrane, and the first flow path and the second flow path are different from each other through the permeation membrane. And a catalyst is present in a reaction zone in which the organic reaction substrate in the first channel and the reactant that has passed through the permeable membrane react with each other. It is what.

  In addition, the present invention is a reaction method in which an organic reaction substrate and a reactant are reacted in the presence of a catalyst using carbon dioxide as a medium using the above-described reaction apparatus, which is introduced through the first flow path. The reactant contained in the carbon dioxide medium is selectively permeated through the reactant selective permeation membrane and introduced into the reaction zone. In the reaction zone, the permeated reactant and the organic reaction introduced through the second flow path. The substrate is reacted in the presence of a catalyst.

In the present invention, hydrogen and oxygen are used as the reactant, and silica membrane, mesoporous silica membrane, Pd membrane, bentonite membrane, alumina membrane, Pd ion exchange membrane, copper-LaNi ₅ membrane, alumino as the reactant selective permeation membrane. A silicate film, a zeolite film, a palladium alloy film, a perovskite film, or a CeO ₂ / ZrO ₂ coated TiO ₂ film is used.

  Further, a heterogeneous catalyst is used as the catalyst, and the heterogeneous catalyst is held so as not to flow out of the reaction zone. Carbon dioxide has a pressure of 4 to 20 MPa and a temperature range of room temperature to 100 ° C., and is preferably in a supercritical or subcritical state.

  In the present invention, a reaction device capable of operating carbon dioxide in a supercritical state in a medium can be used to perform a reaction at a high reaction rate under mild reaction conditions. It is possible to carry out a reaction excellent in a short time.

  In the present invention, carbon dioxide, for example, supercritical or subcritical carbon dioxide is used as a medium, in the presence of a catalyst, from a reactant that has permeated a permselective membrane and an organic reaction substrate, for example, by a reaction such as oxidation or reduction. To an organic compound. As the reaction medium, carbon dioxide is used, and specifically, for example, pressurized carbon dioxide having a pressure of 4 to 20 MPa and a temperature of 35 to 100 ° C., preferably carbon dioxide in a supercritical or subcritical state. Is used.

  Carbon dioxide has three states: gas, liquid, and solid. If it exceeds the critical temperature (Tc = 31.1 ° C) and exceeds the critical pressure (Pc = 7.38 MPa), it will condense even under pressure. Without a boundary between gas and liquid, a single fluid phase appears and this state is defined as a supercritical state.

  Carbon dioxide in a supercritical state above the critical point or in a subcritical state close to the critical state exhibits unusual properties of gases and liquids. That is, carbon dioxide in a supercritical state or a subcritical state has a density close to that of a liquid, a viscosity close to that of a gas, and thermal conductivity and diffusion coefficient exhibit intermediate characteristics between the substrate and the liquid. In addition, since the solubility of gas and organic compounds increases, it has a unique influence on the progress of chemical reactions.

  The temperature and pressure conditions of high-pressure carbon dioxide used in the present invention are, for example, pressure adjustment when supplied from a high-pressure cylinder, heating from the outside of the reactor with a heater or a heating water tank, or the like. It is controlled by the internal heat system. In the flow-type supercritical apparatus, the pressure in the reaction vessel can be easily controlled by a pressure valve. Carbon dioxide used as the reaction medium is not particularly limited, and for example, commercially available pressurized carbon dioxide can be used.

  In the present invention, the reactant is not particularly limited, and may be any substance as long as it has a property of being dissolved in carbon dioxide, permeating through a selective permeable membrane, and reacting with an organic reaction substrate. Even used. Examples of the reactant include hydrogen gas and oxygen gas as the gas. As an organic reaction substrate, any substance can be used without any limitation as long as it is a substance that dissolves in carbon dioxide and reacts with a reactant that has permeated through a permselective membrane in a carbon dioxide medium. Cinnamic aldehyde, citral, and crotonaldehyde are exemplified.

  In the present invention, it is important to use the above-described reaction apparatus. As the reaction performed in the present invention, various reactions are possible depending on the combination of the organic reaction substrate and the reactant, and depending on the reaction. There are no particular restrictions on the production of various compounds. In the present invention, for example, when hydrogen is used as a reactant, a reduction reaction and a hydrogenation reaction proceed. When oxygen is used as a reactant, an oxidation reaction proceeds. More specifically, when cinnamaldehyde is used as an organic reaction substrate and hydrogen is used as a reactive agent, hydrocinnamaldehyde obtained by hydrogenation of cinnamaldehyde and hydrocinnamyl obtained by reducing the aldehyde group to an alcohol group. Alcohol is produced.

  The permeable membrane used in the present invention needs to have a property of selectively permeating the reactant, and preferably a porous inorganic membrane is used, but the reactant is selectively permeated. Any film can be used as long as it has such characteristics. The porosity of the inorganic membrane is an important factor for achieving suitable selection characteristics. The porosity of the membrane may be uniform or inclined. When the pore network is homogeneous throughout, the membrane porosity is said to be uniform, and when the porosity is not homogeneous across the network, it is said to be tilted. In the present invention, a uniform porosity is suitable for uniformly dispersing hydrogen.

Examples of the reactive permeation membrane include a silica membrane, mesoporous silica membrane, Pd membrane, bentonite membrane, alumina membrane, Pd ion exchange membrane, copper-LaNi ₅ membrane, aluminosilicate membrane, zeolite membrane, palladium alloy membrane, perovskite membrane. CeO ₂ / ZrO ₂ coated TiO ₂ film is exemplified. Among these, for example, when hydrogen is used as the reactive agent, examples of the permselective membrane include silica membranes, Pd membranes, and Pd ionization membranes. When oxygen is used as the reactive agent, as the permselective membrane, Examples are perovskite films and CeO ₂ / ZrO ₂ coated TiO ₂ films.

  These permselective membranes may be formed on the surface of a member such as a porous ceramic material. For example, an alumina tube having a permselective membrane formed on the inner surface of an alumina porous tube is made of carbon dioxide containing a reactant. The reactant used as a part of the passage and permeating the part reacts with the organic reaction substrate. Since the reaction of the present invention is carried out under mild conditions, the thermal stability of the film is rarely a big problem.

  In the present invention, the reaction between the organic reaction substrate and the reactant is preferably performed in the presence of a heterogeneous catalyst. As the catalyst, a catalyst having selectivity in the reaction is preferably selected, but the material of the catalyst is not particularly limited, and may be appropriately selected from known reaction catalysts. Specifically, for example, as a selective hydrogenation catalyst, a catalyst made of at least one metal, preferably a noble metal or a transition metal, is introduced into the catalyst chamber of the reactor. In addition, group VIII metal catalysts are exemplified in the selective hydrogenation of unsaturated carbonyl compounds.

  The catalyst is preferably in the form of a calcined powder and is used by being supported on a carrier, and as the carrier, carbon, zeolite, silica, mesoporous material, and the like are suitable. The catalyst needs to be activated in advance before the start of the reaction, and the activation is performed by a reduction reaction with hydrogen, or in particular, by calcination with a mesoporous material, and at this time, the metal catalyst is reduced. Moreover, the catalyst deactivated once used is regenerated by the activation technique already established in each catalyst.

  These catalysts may be introduced into a reaction zone where the organic reaction substrate and the selectively permeated reagent come into contact with each other and the reaction proceeds. As the reaction time elapses, for example, the introduced catalyst flows out of the reaction zone along with the flow of supercritical carbon dioxide and cannot participate in the reaction. Is preferably performed.

  For this purpose, for example, the organic reaction substrate and carbon dioxide can freely pass through the reaction zone, but the amount of catalyst in the reaction zone is reduced by isolating it from other regions by a porous member having characteristics that the catalyst cannot pass through. The reaction can be sustained for a long time without doing so. Specifically, for example, it is preferable to isolate the reaction zone from other regions by a ceramic porous net or the like. Further, for example, the catalyst can be held for a long period of time by installing a porous body firmly supporting the catalyst in the reaction zone.

  In the present invention, an efficient reaction can be carried out by appropriately adjusting the synthesis conditions according to the characteristics of the reaction product, the organic reaction substrate, and the reactant. For example, by appropriately controlling the temperature and pressure of carbon dioxide, the concentration or pressure of the organic reaction substrate and the reactant, the flow rate, the selectivity of the selective permeable membrane and the permeation rate thereof, the reaction time, etc. Thus, the reaction can proceed while preventing side reactions from occurring.

  The flow reactor of the present invention has, for example, a mechanism capable of reaching reaction conditions in a range of reaction temperature of room temperature to 100 ° C. and pressure of 4 to 20 MPa within a time of several seconds or less. A flow-type high-pressure reactor is used. The elapsed time to the set reaction conditions in the present invention is extremely shortened as compared with, for example, a batch reactor (1 to 5 hours) and a conventional continuous reactor (10 to 120 seconds). Thereby, the reaction yield and the selectivity of a product can be improved greatly.

  In the present invention, by adopting the reaction conditions described above, for example, the organic reaction substrate and the reactant can be reacted in a time of 10 minutes to 6 hours. When using a flow reactor, the reaction time is controlled by controlling the reaction temperature, reaction pressure, carbon dioxide flow rate, reactor shape, reactor inner diameter, reactor flow path length, etc. The reaction time can be controlled.

  As a more preferable reaction time, a value of 1 to 3 hours can be selected, and a value in the range of 2 hours can be selected most preferably, but is not limited to these values. By setting the reaction condition to an appropriate value, the elapsed time until reaching the set reaction condition can be shortened, a complex reaction is less likely to occur, and a sharp reaction is possible. That is, in the present invention, it becomes possible to synthesize the target compound with high selectivity. In the present invention, a large amount of product can be obtained in a short time, and a method for producing a compound with high production efficiency can be constructed and provided.

  The resulting reaction mixture contains the target compound at a high conversion rate, but may contain impurities such as unreacted raw materials or by-products. Can be obtained in purity. The separation and purification method is not particularly limited, and distillation extraction, ion exchange treatment, and the like, which are commonly used in industry, are applied.

Next, the apparatus of the present invention will be described in detail by taking as an example a reaction apparatus using hydrogen gas as a reactant and supercritical carbon dioxide (scCO ₂ ) as a medium. FIG. 1 is a schematic diagram showing the structure of a newly developed reactor according to the present invention. The reactor is installed in a constant temperature water bath, and a syringe pump for introducing H ₂ and scCO ₂ into the reactor is connected to an end D of the reactor.

The organic reaction substrate and scCO ₂ are mixed in the mixer C by the HPCL pump, and then supplied to the reactor through the channel G. The other end E of the reactor is provided with two pressure gauges I1 and I2, and individually checks the pressure of H ₂ + scCO ₂ and the pressure difference when performing the reaction. After completion of the reaction, the reaction product is depressurized through the back pressure controller J and collected in a cold trap. Unreacted H ₂ and scCO ₂ are discharged through the other pathway K.

  2 (a) and 2 (b) show enlarged fracture surfaces of the reactor and the membrane unit part, respectively. The reactor has, for example, a double tube structure of (i) an outer tube A and (ii) an inner tube B. The outer tube A is made of a stainless steel SUS316 tube having a diameter of 2.55 cm, and the inner tube B is made of a tube having a diameter of 0.9 cm and a length of 30 cm. The outer tube A has a catalyst inlet C and is tightly sealed so that the reaction gas does not leak from other than the inlet and outlet. The inner pipe B is composed of three parts B1, B2, and B3, and B1 and B3 are made of stainless steel SUS316.

The central portion B2 is composed of a tube having a hydrogen selective permeable silica membrane supported by Al ₂ O ₃ on its inner surface. The portion where the organic reaction substrate and H ₂ selectively permeated from the silica membrane come into contact is the reaction zone, and the catalyst is introduced into this zone. In order to efficiently hold the catalyst in the reaction zone, the reaction zone is isolated from other parts by an Al ₂ O ₃ net or the like through which the catalyst particles cannot pass to prevent the catalyst from flowing out. The hydrogen selective permeable mesoporous silica membrane is formed on the inner wall surface of the Al ₂ O ₃ tube by a room temperature method using a triblock copolymer.

Operating conditions of the reaction method or reaction apparatus of the present invention, for example, reaction temperature, CO ₂ pressure, H ₂ pressure, organic reaction substrate concentration, composition ratio of organic reaction substrate and CO ₂ mixture, flow rate thereof, etc. Since it is wide, the reaction is easy to carry out. General reaction conditions for carrying out the reaction of the present invention are shown below. These reaction conditions are selected in the case of using a heterogeneous catalyst in an scCO ₂ medium in the high-pressure reactor of the present invention. Suitable for chemical diffusion and hydrogenation reactions.
1) Carbon dioxide pressure: 4-20 MPa, preferably 6-16 MPa, more preferably 6-12 MPa
2) Hydrogen gas pressure: 0.1-4 MPa, more preferably 0.2-2 MPa
3) Reaction temperature: room temperature to 100 ° C, more preferably 35 to 70 ° C
4) Flow rate of the mixture of organic reaction substrate and scCO ₂ : Organic reaction substrate flow rate to be hydrogenated 0.01 to 2.00 ml / min, more preferably 0.05 to 0.1 ml / min

Compact invention, in scCO _2, a reaction system utilizing permselective heterogeneous catalyst and the membrane, which combines reaction via a selectively permeable membrane, and scCO ₂ was used as a medium the reaction, the advantages of both Developed and developed a simple reaction system. In the present invention, for example, a cinnamaldehyde hydrogenation reaction can be carried out at a total pressure of 10 MPa and a reaction temperature of 50 ° C. in the presence of a mesoporous catalyst.

The silica permeable membrane used in the present invention has a clear advantage compared to membranes described in the prior art. Among them, one of the great advantages is that a high pressure difference is not necessarily required because carbon dioxide flows through a highly permeable membrane. In addition, the reaction method of the present invention makes it possible to derive various possibilities of reaction using a heterogeneous catalyst in scCO ₂ .

In the present invention, advantages such as higher catalytic activity and higher efficiency can be obtained by using a membrane reactor in scCO ₂ . Moreover, this apparatus can isolate | separate the target reaction product from a reaction mixture continuously, without encountering any difficulty. In addition, the reaction apparatus of the present invention can be used for the oxidation reaction of an organic reaction substrate in scCO ₂ by simply exchanging only the membrane portion with an oxygen selective permeable membrane. Furthermore, the reaction process of the present invention makes it possible to carry out various reactions under a wide variety of reaction conditions that are environmentally friendly.

The reactant permselective membrane plays a role of selectively permeating and transferring a reactant such as H ₂ to a catalyst bed in a large amount. In the present invention, by using scCO ₂ as a medium, the characteristics of a supercritical medium that does not limit the mass transfer are exhibited, and the selective diffusion and transfer of hydrogen gas to the catalyst bed is facilitated. The supply of ₂ is not limited. Thus, according to the present invention, it becomes easy to obtain a high degree of reaction selectivity and efficient reactivity.

The present invention has the following effects.
(1) A method and apparatus for synthesizing an organic compound capable of performing a reaction in a short time and in a high yield by reacting an organic reaction substrate and a reagent through a permselective membrane using carbon dioxide as a medium. Can be provided.
(2) It is possible to provide a reaction method and apparatus capable of achieving a high reaction rate under mild reaction conditions and performing a reaction excellent in selectivity of a target product.
(3) a reactant selected from hydrogen, by selecting the reactive gases oxygen, efficient oxidation, reduction, it is possible to perform the hydrogenation reaction.
(4) In a supercritical carbon dioxide medium, the reaction can always be carried out in the presence of a sufficient amount of a heterogeneous catalyst, and the reaction utilizing an inorganic permselective membrane with no problem in swelling and stability. An apparatus can be provided.
(5) To provide a reaction apparatus that uses a supercritical carbon dioxide medium and a permselective membrane and can easily control the reaction without being affected by the solubility of the organic substrate and the reactant and the equilibrium constant. it can.
(6) It is possible to provide a compact reactor that is safe and environmentally friendly, capable of minimizing the expense required for the handling of the catalyst and the energy required for operating the apparatus.

  EXAMPLES Next, although this invention is demonstrated concretely based on an Example, this invention is not limited at all by the following Examples.

  In this example, the selective hydrogenation reaction of cinnamaldehyde (α, -β unsaturated aldehyde) was performed using supercritical carbon dioxide as a medium. The reaction process estimated under the reaction conditions set in this example is shown in the following chemical formula (Formula 1).

An outline of the structure of the high-pressure reactor used in this example is shown in FIG. The reactor is installed in a constant temperature water bath, and at the end D of the reactor, a syringe pump (A: with pressure resistance up to 49 MPa, ISCO model 260D for introducing H ₂ and scCO ₂ into the reactor) ) Are connected. The organic reaction substrate and scCO ₂ were fed by an HPCL pump (B: JASCO880PU model), mixed in the mixer C, and then supplied to the reactor through the channel G. At the other end E of the reactor, two pressure gauges I1 and I2 are provided to individually check the pressure of H ₂ + scCO ₂ and the pressure difference during the reaction. After completion of the reaction, the reaction product was depressurized by the back pressure controller J, collected in a cold trap, and unreacted H ₂ and scCO ₂ were discharged from the other channel K.

  2 (a) and 2 (b) show enlarged fracture surfaces of the reactor and the membrane unit, respectively. The reactor has a double structure of (i) outer tube A and (ii) inner tube B. The outer tube A is made from a stainless steel SUS316 tube having a diameter of 2.55 cm, and the inner tube B is made from a tube having a diameter of 0.9 cm and a length of 30 cm. The outer tube A is provided with a catalyst inlet C and is tightly sealed so that the reaction gas does not leak from other than the inlet and outlet. The inner pipe B is composed of three parts B1, B2, and B3, and B1 and B3 are made of stainless steel SUS316.

The central portion B2 is composed of a tube having a hydrogen selective permeable silica membrane supported on Al ₂ O ₃ on its inner surface. The reaction zone is isolated from other parts by an Al ₂ O ₃ net that allows scCO ₂ to pass but not catalyst particles so that the catalyst is held in the reaction zone where the reaction substrate and the selectively permeated reactant react. Has been. The hydrogen selective permeable mesoporous silica membrane is formed on the inner wall surface of the Al ₂ O ₃ tube by a room temperature method using a triblock copolymer.

In carrying out the reaction using the reactor of this example, first, 2.13 g of calcined Pt-MCM-41 (˜1 wt% Pt) catalyst was introduced from the catalyst inlet C of FIG. The reactor was placed in a 50 ° C. water bath for 90 minutes to keep the reaction temperature constant. Before introducing H ₂ gas and cinnamaldehyde (organic reaction substrate) as reactants, the reactor was carefully checked for leaks to confirm reactor safety.

To start the reaction, 1 MPa of H ₂ was introduced into the Al ₂ O ₃ pipe having a silica membrane on its inner wall by a syringe pump, and then 9 MPa of CO ₂ was introduced into the pipe at a flow rate of 2.00 ml / min. did. While these were introduced, the total pressure in the reactor was monitored by the pressure detector I1 shown in FIG. Next, the organic reaction substrate and carbon dioxide were mixed, and the catalyst was passed at a steady flow rate of 0.1 ml / min. A back pressure controller was used to separate unreacted gas and reaction product, and the reaction product was collected in a cool trap. The reaction product was analyzed by GC (HP6890) having a capillary column and a flame ionization detector. The results are shown in Table 1.

By the above reaction, 75% and 25% of hydrocinnamaldehyde and hydrocinnamyl alcohol were obtained from cinnamaldehyde in a very short time of 2 minutes, respectively. As a result, H ₂ penetrated and passed through the silica membrane to activate the catalyst, and then contacted the cinnamaldehyde and the medium (CO ₂ ) in the presence of the catalyst, so that the cinnamaldehyde was subjected to a hydrogenation reaction. I understand.

By selecting and using a catalyst suitable for this reaction method, for example, Pt-MCM-41, the reaction could proceed selectively at high speed. By using a hydrogen selectively permeable porous silica membrane, the H ₂ required for the reaction is distributed to the catalyst. The reaction is controlled by the selective diffusion phenomenon caused by this membrane, so that hydrocinnamaldehyde and hydrocinna Mill alcohol was obtained with high selectivity.

  As described above in detail, the present invention relates to a reaction method and a reaction apparatus for reacting an organic reaction substrate and a reactant through a permselective membrane in the presence of a catalyst using carbon dioxide as a medium. According to the present invention, it is possible to provide a new reaction method and an apparatus therefor which have both excellent characteristics of a membrane reaction method using a permselective membrane and a reaction method using supercritical carbon dioxide as a medium. INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a method for synthesizing an organic compound and an apparatus for the same that can carry out the reaction in a high yield in a short time and that is excellent in selectivity of the reaction product.

  The present invention provides an efficient and simple reaction process for synthesizing compounds important as starting materials or intermediates for a wide range of organic industrial products such as pharmaceuticals, agricultural chemicals, dyes, resins, etc. Without being limited to the agent and the reaction system, it can be widely applied to the synthesis of various organic compounds. According to the present invention, for example, an oxidation reaction in which an olefinic hydrocarbon is oxidized to produce a carbonyl compound and an epoxide, a hydrogenation reaction of an unsaturated compound, a hydrocarbonyl reaction of an olefinic hydrocarbon, a reduction reaction of an aldehyde to an alcohol, etc. These various oxidation and reduction reactions can be efficiently realized. Further, the present invention makes it possible to provide an organic compound synthesis reaction and apparatus that is compact, can minimize energy consumption, and is environmentally friendly.

The outline | summary of the structure of the membrane reaction apparatus of this invention is shown. The reactor is enlarged to show the detailed internal structure.

Explanation of symbols

(Reference in FIG. 1)
A: Syringe pump B: HPLC pump C: Mixer D: Reactor inlet end E: Reactor outlet end G: Organic reaction substrate and carbon dioxide flow path H: Reaction product and carbon dioxide flow path I1 I2: Pressure gauge J: Back pressure controller K: Unreacted H ₂ and CO ₂ outlets V1, V2: Pressure regulator (reference numeral in FIG. 2)
A: Outer reactor tube B (B1, B2, B3): Reactor tube B3: Membrane unit C: Catalyst inlet

Claims (6)

A reaction apparatus for reacting an organic reaction substrate and a reactant in the presence of a catalyst using carbon dioxide as a medium,
A flow path of carbon dioxide containing a reactive agent (first flow path), a flow path of carbon dioxide containing an organic reaction substrate (second flow path), and a reactive agent permselective membrane supported by a porous member ; The first flow channel and the second flow channel form an inner tube or an outer tube having a multi-tube structure, and the reactant in the first channel is selectively transmitted to another channel through the reactant selective permeation membrane. It is arranged so as to be permeable, and has a structure in which a catalyst exists in a reaction zone in which a reaction agent that has passed through the organic reaction substrate in the second flow path and the reagent selective permeation membrane reacts,
Carbon dioxide, the pressure range of 4～20MPa, and a carbon dioxide temperature ranging from room temperature to 100 ° C., the reactor in which the reactants, characterized in that hydrogen or oxygen reactive gas.   The reaction apparatus according to claim 1, wherein the catalyst is a heterogeneous catalyst. Reagent selective permeation membrane is silica membrane, mesoporous silica membrane, Pd membrane, bentonite membrane, alumina membrane, Pd ion exchange membrane, copper-LaNi ₅ membrane, aluminosilicate membrane, zeolite membrane, palladium alloy membrane, perovskite membrane, or CeO The reaction apparatus according to claim 1, which is a ₂ / ZrO ₂ -coated TiO ₂ film.   The reaction apparatus according to any one of claims 1 to 3, wherein the carbon dioxide is carbon dioxide in a subcritical or supercritical state. Using the reaction apparatus according to any one of claims 1 to 3, an organic reaction in the presence of a heterogeneous catalyst using carbon dioxide in a pressure range of 4 to 20 MPa and a temperature range of room temperature to 100 ° C as a medium. A reaction method of reacting a substrate and a reactive agent,
A flow path of carbon dioxide containing a reactive agent (first flow path), a flow path of carbon dioxide containing an organic reaction substrate (second flow path), and a reactive agent permselective membrane supported by a porous member; The first flow channel and the second flow channel form an inner tube or an outer tube having a multi-tube structure, and the reactant in the first channel is selectively transmitted to another channel through the reactant selective permeation membrane. In a reaction apparatus having a structure in which a catalyst is present in a reaction zone that is disposed so as to be permeable and in which a reaction agent that has passed through an organic reaction substrate in a second flow path and a reaction agent permeation membrane has reacted. Using a reactive gas such as hydrogen or oxygen as the reactant, the reactant contained in the carbon dioxide medium introduced through the first flow path is selectively permeated through the reactant selective permeation membrane to react the reaction zone. And the reaction agent permeated in the reaction zone and the organic reaction substrate introduced through the second flow path. The reaction wherein the reacting in the presence of the catalyst.   6. The reaction method according to claim 5, wherein the organic reaction substrate and the reactant are reacted using carbon dioxide in a subcritical or supercritical state as a medium.