WO2014142324A1 - Continuous direct synthesis/recovery method for hydrogen peroxide using catalyst-coated reaction tube, and device therefor - Google Patents

Abstract

The present invention provides a continuous direct synthesis/recovery method for hydrogen peroxide, and a device therefor. This method is characterized by: using a reaction tube obtained by coating the interior wall of a hollow tube with a precious-metal thin film; continuously directly synthesizing hydrogen peroxide from hydrogen and oxygen inside the reaction tube; and continuously recovering the synthesized hydrogen peroxide as hydrogen peroxide. This device is characterized by being equipped with: a reaction tube obtained by coating the interior wall of a hollow tube with a precious-metal thin film; a means for supplying the reaction tube with hydrogen as a starting-material gas and oxygen or air in the gas-phase; a means for supplying a reaction medium in the aqueous phase; and a means for continuously recovering hydrogen peroxide synthesized inside the reaction tube immediately after synthesis thereof, from water or from an acid-water solution. As a result, the present invention is capable of producing and supplying highly pure hydrogen peroxide intended for semiconductors and hydrogen peroxide free of organic materials and intended for microanalysis reagents.

Description

Method and apparatus for continuous direct synthesis and recovery of hydrogen peroxide using a catalyst-coated reaction tube

The present invention relates to a method and apparatus for continuous direct synthesis and recovery of hydrogen peroxide using a catalyst-coated reaction tube, and more specifically, a noble metal thin film of a catalyst is coated on the inner wall of a hollow tube by electroless plating or the like. A method for directly synthesizing hydrogen peroxide by directly synthesizing hydrogen peroxide from hydrogen and oxygen using a reaction tube, and further continuously recovering the hydrogen peroxide synthesized directly as hydrogen peroxide water, and It relates to the device. In the present specification, a reaction tube in which a hollow inner wall of a catalyst is coated with a noble metal thin film of a catalyst may be referred to as a catalyst-coated reaction tube.

Hydrogen peroxide is an oxidant with a low environmental impact that becomes water after reaction with an object to be treated. For example, in a field such as water treatment, sterilization, bleaching, and cleaning, particularly in a field such as semiconductor cleaning. It's being used. At present, almost all hydrogen peroxide on the market is synthesized by a sequential oxidation / reduction method (anthraquinone method) of anthraquinone, which is an aromatic organic compound. Since the anthraquinone method is a multistage reaction and consumes a large amount of organic reagents and organic solvents, the problem of environmental pollution due to them has been pointed out in recent years.

On the other hand, the process of directly synthesizing hydrogen peroxide from hydrogen and oxygen is expected as a simple synthesis process with low environmental impact. And about this direct synthesis, the method of directly synthesize | combining hydrogen peroxide from hydrogen and oxygen using various noble metal catalysts etc. is examined from various viewpoints.

As a problem in the technology for directly synthesizing hydrogen peroxide from hydrogen and oxygen, it is most important to handle so-called squeal gas, which is a mixed gas of hydrogen and oxygen, safely. In addition, as challenges for the industrialization of this technology, securing the production amount of hydrogen peroxide, increasing the concentration, and reducing the amount of expensive noble metal catalyst used are important. Up to now, various technological developments and proposals have been made to overcome these problems. In recent years, as a prior art, for example, a mixed gas of hydrogen, oxygen, and nitrogen is continuously supplied to a metal catalyst colloid dispersion. However, a direct synthesis method for accumulating hydrogen peroxide in the liquid has been proposed (Cited document 1).

In this method, nitrogen is used to secure the safety of direct synthesis of hydrogen peroxide, and the concentration of the mixture is increased by continuously introducing a mixed gas of the raw material gas into the fixed liquid. However, since this method is a batch type, it is difficult to secure the production amount, and a method for recovering the metal catalyst colloid from the synthetic hydrogen peroxide solution is required. There were problems such as re-decomposition of hydrogen oxide.

As another prior art, in the continuous synthesis of hydrogen peroxide, liquid (water) and gaseous hydrogen, oxygen, and nitrogen are simultaneously supplied to the solid catalyst packed in the column, A method for continuously synthesizing hydrogen peroxide by using it has been proposed (Cited document 2).

In this method, the liquid flows as a film on the surface of the solid catalyst particles, the gas forms a continuous phase, and it is possible to secure the production amount of hydrogen peroxide by a continuous process. However, with this method, it is necessary to increase the amount of inert gas introduced in order to ensure safety. For this purpose, the method involves reducing the amount of hydrogen and oxygen involved in the synthesis, the possibility that the synthesized hydrogen peroxide will come into contact with the catalyst again and decompose, and packing the catalyst in a column. There are problems such as an increase in the amount of catalyst used and an increase in load resistance due to mass transfer in the column.

Also, as another prior art, a continuous synthesis method in which a solid catalyst is filled in a continuous microchannel having, for example, a fine channel has been proposed (Cited document 3). In this method, the hydrogen quenching distance is secured using microchannels, and the gas and liquid are supplied simultaneously, so that water in the reaction field promotes the extension of the quenching distance and ensures safety. However, this method increases the load resistance in mass transfer by filling the catalyst metal particles in the microchannel, and controls the reactivity of the reaction field in the three phases of the catalyst surface, liquid phase, and gas phase. There were problems such as being complicated.

In the prior art, the heterogeneous catalyst used for direct synthesis includes, for example, various kinds of catalysts such as single metal particles and alloy particles, activated carbon, metal oxide supported catalyst, and metal complex modified catalyst. Among these, various proposals have been made on metals such as catalysts supporting Pd, Pt, Au, PdO, and Pd / C, Pd / Al ₂ O ₃ (for example, cited references 4 to 6). . However, any catalyst has a problem that it is required to be used as fine particles or a colloid in order to increase the specific surface area.

In these methods, a packed solid catalyst is used. However, in general, in the direct synthesis of hydrogen peroxide, the synthesis catalyst can also be a decomposition catalyst for hydrogen peroxide, there is a risk of explosion due to a gas continuous phase containing hydrogen and oxygen, load resistance in mass transfer From the standpoint of the need for reduction of the above, it is considered that the application of the filling type solid catalyst is not preferable.

JP 2007-84372 A JP-A-6-183703 WO2010 / 044271 JP-A-5-213607 Japanese translation of publication No. 2004-516721 Japanese Patent Laid-Open No. 51-4097

Under such circumstances, the present inventors, in view of the above-mentioned prior art, as a result of intensive research aimed at solving the above-mentioned problems in the prior art, resulted in the noble metal of the catalyst on the hollow tube inner wall. By using a reaction tube coated with a thin film by electroless plating, etc., it is possible to ensure smooth mass transfer and to form a suitable or optimal three-phase interface consisting of the catalyst surface, liquid phase, and gas phase. I found out. Furthermore, the present inventors divide the mixed gas of hydrogen and oxygen, which is the squeal gas, into a liquid by forming a slag flow in which the gaseous gas phase and the liquid liquid phase state are alternately continued. As a result, it was found that the safety of the direct synthesis of hydrogen peroxide can be ensured, and further research has been made to complete the present invention.

An object of the present invention is to provide a clean, safe and industrializable production process for hydrogen peroxide production that can replace the conventional anthraquinone method with high energy consumption and possible environmental pollution. It is. That is, the present invention forms a suitable three-phase interface consisting of a catalyst surface, a liquid phase, and a gas phase, and establishes a method for directly synthesizing hydrogen peroxide safely from hydrogen and oxygen. An object of the present invention is to provide an industrializable direct hydrogen peroxide synthesis method and apparatus capable of operating safely and stably while reducing the amount of noble metal catalyst used and ensuring the productivity of the target product. is there.

In order to solve the above problems, the present invention comprises the following technical means.
(1) A method for directly synthesizing hydrogen peroxide from hydrogen and oxygen,
Using a reaction tube in which a hollow tube inner wall is coated with a noble metal thin film, a raw material gas hydrogen, an oxygen or air gas phase, and a reaction medium aqueous phase are supplied to a flow path inside the reaction tube, Under the reaction temperature and reaction pressure conditions, hydrogen peroxide is continuously synthesized directly from hydrogen and oxygen inside the reaction tube, and the synthesized hydrogen peroxide is continuously recovered as hydrogen peroxide water. Direct synthesis method of hydrogen peroxide.
(2) A thin film comprising at least one of palladium, an alloy of palladium and gold, a gold nanoparticle deposited on the surface of the palladium thin film, an alloy of palladium and silver, and a porous palladium film. The method for directly synthesizing hydrogen peroxide according to (1) above, wherein a reaction tube coated with is used.
(3) The method for directly synthesizing hydrogen peroxide according to (1), wherein a reaction tube in which the noble metal thin film of the reaction tube is coated by electroless plating is used.
(4) The method for directly synthesizing hydrogen peroxide according to (1) or (3), wherein the noble metal thin film has a thickness in the range of 0.5 to 2 μm.
(5) As the hollow tube, a stainless steel tube, an Inconel tube, a Hastelloy tube, a titanium tube, a corrosion-resistant tube selected from the above, or an inner surface titanium-lined stainless steel tube, an Inconel tube, a Hastelloy tube The method for directly synthesizing hydrogen peroxide according to any one of (1) to (4), wherein any one of the selected corrosion-resistant double pipes is used.
(6) The method for directly synthesizing hydrogen peroxide according to any one of (1) to (4), wherein a fumed silica tube is used as the hollow tube.
(7) A thin film comprising at least one of palladium, an alloy of palladium and gold, a gold nanoparticle deposited on the surface of the palladium thin film, an alloy of palladium and silver, and a porous palladium film as the reaction tube. Is produced by electroless plating inside the reaction tube, the oxide film of the base metal is produced by high-temperature oxidation at 600 ° C. or higher or supercritical water oxidation at 374 ° C. or higher. Direct synthesis method of hydrogen oxide.
(8) The peroxidation according to any one of (1) to (7), wherein the inner diameter of the reaction tube is 10 mm or less, 0.05 mm or more, or 5 mm or less and 0.1 mm or more. Direct synthesis method of hydrogen.
(9) The reaction temperature is in the range of 0 to 80 ° C., or in the range of 5 to 50 ° C., and the reaction pressure is in the range of 0.1 to 50 MPa, or is in the range of 0.1 to 20 MPa. The method for directly synthesizing hydrogen peroxide according to any one of (1) to (8).
(10) The hydrogen peroxide according to any one of (1) to (9), wherein the hydrogen peroxide synthesized inside the reaction tube is continuously recovered as hydrogen peroxide water with water or an acid aqueous solution. Direct synthesis method.
(11) The water or acid aqueous solution for recovering hydrogen peroxide synthesized inside the reaction tube contains one or more ions of fluoride ion, chloride ion, bromide ion, and iodide ion. The method for directly synthesizing hydrogen peroxide according to 10).
(12) The acidic aqueous solution contains at least one of fluorine, chlorine, bromine and iodine, and all of the materials have a total concentration in the acidic aqueous solution in the range of 0.01 to 100 mg / L. The method for directly synthesizing hydrogen peroxide according to (11) above.
(13) When continuously recovering the hydrogen peroxide synthesized in the reaction tube, the raw material gas phase gas and the aqueous phase liquid are mixed with a mixer, and the volume flow rate ratio is adjusted, whereby the raw material A slag flow in which the phase states of the gas phase and the aqueous phase are alternately continued is formed, and using the slag flow, the hydrogen peroxide immediately after synthesis synthesized in the reaction tube is continuously used as a hydrogen peroxide solution. The method for directly synthesizing hydrogen peroxide according to (10) or (11), wherein the hydrogen peroxide is recovered.
(14) The volume mixing ratio of gas and liquid is gas 5 to 50: liquid 1, and the volume flow rate ratio of the raw material gas phase and the recovered water phase is 50 or less with respect to the water phase 1 or water The method for directly synthesizing hydrogen peroxide according to (13), wherein a slag flow is formed with a gas phase of 10 or less with respect to phase 1.
(15) The inner diameter of the outflow part of the mixer that mixes the gas of the raw material gas phase and the liquid of the aqueous phase, the inner diameter of the reaction tube and the inner diameter of the reaction tube joint, and the slag flow size is not changed by the flow path. (13) The method for directly synthesizing hydrogen peroxide according to (14).
(16) A mass flow controller is used for the raw material gas phase and a metering pump is used for the aqueous phase, and the flow rate and discharge pressure are controlled using a micromixer. The method for directly synthesizing hydrogen peroxide according to any one of (13) to (15), wherein a slag flow is generated.
(17) The method for directly synthesizing hydrogen peroxide according to any one of (13) to (16), wherein a stable slag flow is generated using a T-shaped micromixer as the micromixer.
(18) The volume mixing ratio of hydrogen and oxygen is 10 to 33% hydrogen and 90 to 67% oxygen, and the ratio of oxygen to hydrogen in the source gas phase (oxygen / hydrogen) is 1.6 or more, or The method for directly synthesizing hydrogen peroxide according to any one of (1) to (13), wherein the ratio of oxygen to hydrogen is 2.0 or more.
(19) The method for directly synthesizing hydrogen peroxide according to any one of (10) to (18), wherein the recovered aqueous phase from the reaction tube is recycled to the reaction tube.
(20) An apparatus for continuously and directly synthesizing hydrogen peroxide from hydrogen and oxygen,
A reaction tube in which the inner wall of a hollow tube is coated with a noble metal thin film, a means for supplying hydrogen as a raw material gas and a gas phase of oxygen or air, a means for supplying a water phase of a reaction medium, and a reaction tube An apparatus for directly synthesizing hydrogen peroxide, comprising means for continuously recovering hydrogen peroxide synthesized immediately after synthesis with water or an aqueous acid solution.
(21) As a reaction tube in which a noble metal thin film is coated on the inner wall of the tube by electroless plating, the reaction tube is coated with a thin film composed of at least one of palladium, an alloy of palladium and gold, an alloy of palladium and silver, and a porous film of palladium. The apparatus for directly synthesizing hydrogen peroxide according to the above (20), comprising a reaction tube.
(22) The apparatus for directly synthesizing hydrogen peroxide according to (20), wherein a reaction tube in which the noble metal thin film of the reaction tube is coated by electroless plating is used.
(23) As the hollow tube, a stainless steel tube, an Inconel tube, a Hastelloy tube, a titanium tube, a corrosion resistant tube selected from the above, or an inner surface titanium-lined stainless steel tube, an Inconel tube, a Hastelloy tube The apparatus for directly synthesizing hydrogen peroxide according to any one of (20) to (22), wherein any one of the selected corrosion-resistant double pipes is used.
(24) The hydrogen peroxide direct synthesis apparatus according to any one of (20) to (22), wherein a fumed silica tube is used as the hollow tube.
(25) A thin film comprising at least one of palladium, an alloy of palladium and gold, a palladium nanoparticle deposited with gold nanoparticles, an alloy of palladium and silver, and a porous palladium film as the reaction tube. Is produced by electroless plating inside the reaction tube, and a metal oxide film used as a base is manufactured by high-temperature oxidation at 600 ° C. or higher or supercritical water oxidation at 374 ° C. or higher (23 ) Direct hydrogen peroxide synthesis apparatus.
(26) The method according to any one of (20) to (25), further including a mixer that forms a slag flow in which a phase state of a raw material gas phase and an aqueous phase are alternately continued in a flow path entering the reaction tube. An apparatus for directly synthesizing hydrogen peroxide as described.
(27) In any one of the above (20) to (24), the inner diameter of the outlet of the mixer for mixing the raw material gas and the recovered water, the inner diameter of the reaction tube, and the inner diameter of the reaction tube joint are the same. An apparatus for directly synthesizing hydrogen peroxide as described.
(28) The method according to any one of (20) to (27), further comprising means for continuously recovering the hydrogen peroxide synthesized in the reaction tube as a hydrogen peroxide solution using water or an aqueous acid solution. Hydrogen peroxide direct synthesis equipment.
(29) A mass flow controller for controlling the supply of the raw material gas phase and a metering pump for controlling the supply of the aqueous phase, and a micromixer for mixing the raw material gas phase and the aqueous phase are disposed downstream of the mass flow controller and the metering pump. The direct synthesis of hydrogen peroxide according to any one of (20) to (28), wherein a slag flow in which the phase states of the raw material gas phase and the aqueous phase are alternately continued is generated. apparatus.
(30) The hydrogen peroxide direct synthesis apparatus according to any one of (26) to (29), wherein a T-shaped micromixer is used as the micromixer to generate a stable slag flow. .
(31) The apparatus for directly synthesizing hydrogen peroxide according to any one of (20) to (29), further comprising a recirculation means for recirculating the recovered aqueous phase discharged from the reaction tube to the reaction tube .

Next, the present invention will be described in more detail.
The present invention uses a reaction tube having a hollow tube inner wall coated with a noble metal thin film, and directly synthesizes hydrogen peroxide from hydrogen and oxygen inside the reaction tube. The present invention provides a method and an apparatus for directly synthesizing hydrogen peroxide comprising continuously recovering hydrogen water.

The reaction tube used in the present invention is composed of a hollow reaction tube, that is, a tubular hollow tubule, and it is preferable to increase the coverage area of the noble metal thin film in the internal space of the hollow tubule. In order to increase the area / volume ratio, a hollow thin tube having an inner diameter of 0.05 mm to 10 mm is used as the reaction tube. That is, the inner diameter of the reaction tube is 10 mm or less, preferably 5 mm or less. Further, in order to ensure sufficient material diffusion and thermal diffusion inside the hollow thin tube, the inner diameter of the reaction tube is 1 mm or less and 0.1 mm. The above is desirable, and further considering the pressure loss, it is desirable that the thickness is 0.25 mm or more.

Also, the length of the hollow thin tube constituting the reaction tube is an important factor that determines the contact time of the catalyst with the noble metal thin film in the reaction. From this, the longer the hollow tube is, the higher the hydrogen conversion efficiency is. However, if it is too long, hydrogen peroxide once synthesized may be decomposed again. Further, since the pressure loss increases as the length of the hollow thin tube increases, a length at which these are suitable or optimal is selected. Specifically, since the volume of the hollow thin tube constituting the reaction tube changes depending on the inner diameter of the reaction tube used, the reaction time (gas average residence time) varies even with the same length. It cannot be decided in general.

Furthermore, since the inner area (catalyst covering area) / volume (specific surface area) changes depending on the inner diameter, the reaction results differ depending on the inner diameter even with the same volume (same reaction time), and a suitable or optimal reaction time for each inner diameter. That is, the length of the hollow tubule is selected. When the inner diameter is 1 mm, the reaction time is selected within 2 minutes, preferably within 1 minute.

For the coating of the catalyst noble metal thin film on the inner surface of the hollow thin tube constituting such a reaction tube, an electroless plating technique that can be achieved relatively simply by introducing the plating solution into the hollow thin tube is applied. Can do. This method of electroless plating is advantageous because the thickness of the plating film can be controlled by the concentration of the plating solution and the amount of liquid flow. This electroless plating method has an advantage that a metal thin film can be coated even when the material of the hollow thin tube constituting the reaction tube is a surface of non-conductive glass, ceramics, plastic, etc. in addition to metal. is doing.

As the material for the tube-shaped hollow thin tube constituting the reaction tube used in the present invention, for example, metals, alloys, glass, ceramics, plastics and the like can be preferably used. Corrosion-resistant titanium, nickel alloy, chromium alloy, and iron alloy are used as the metallic hollow tubule. Furthermore, in order to improve chemical resistance, a titanium or titanium alloy lining is used. The hollow tube is preferably a corrosion resistant tube selected from, for example, a stainless tube, an Inconel tube, a Hastelloy tube, a titanium tube, or a stainless tube, an Inconel tube, a Hastelloy tube provided with an inner surface titanium lining. A fumed silica tube can be used.

When titanium or a titanium alloy is used for the lining, a silane coupling treatment is performed as a pretreatment for electroless plating. In this case, it is preferable to oxidize the titanium surface. As the oxidation treatment of the titanium surface, it is preferable to form a strong oxide film by high-temperature oxidation treatment at 600 ° C. or higher or supercritical water oxidation treatment at 374 ° C. or higher.

For glass, silica glass capillaries used for gas chromatography columns, for ceramics, tubes of alumina, titania, zirconia, etc., for plastics, tubes of polypropylene, polyethylene, polyamide, etc. are used as suitable materials.

In the present invention, the reaction tube is a thin film made of at least one of palladium, an alloy of palladium and gold, a gold nanoparticle deposited on the surface of the palladium thin film, an alloy of palladium and silver, and a porous film of palladium. A reaction tube coated with is used. The inner wall of the tubular hollow thin tube constituting the reaction tube is coated with the noble metal thin film of the catalyst by adding a seed of palladium to the inner wall of the tube, and then a plating solution containing a complexing agent, a noble metal salt and a reducing agent. This is achieved by passing the liquid through the hollow thin tube and performing electroless plating. For the electroless plating solution to be used, use metal salts such as palladium, silver, platinum, rhodium, etc., these metal complexes, complexing agents that can dissolve them stably, and reducing agents in an appropriate solvent. Can do.

The film thickness of the noble metal thin film of the catalyst can be controlled by the flow rate of the electroless plating solution used. Preferably, the flow rate of the electroless plating solution is selected in the range of 0.1 to 5 μm. It is. In order to reduce the amount of noble metal used and to ensure a uniform plating film, the thickness of the noble metal thin film of the catalyst is more preferably in the range of 0.5 to 2 μm.

In the present invention, the hydrogen of the source gas, the gas phase of oxygen or air, and the aqueous phase of the reaction medium are supplied to the flow path inside the reaction tube, and inside the reaction tube under the predetermined reaction temperature and reaction pressure conditions. Sequentially directly synthesize hydrogen peroxide from hydrogen and oxygen. In that case, for example, while controlling the flow rate and discharge pressure of the raw material gas phase and the aqueous phase, respectively, the gas of the raw material gas phase and the liquid of the aqueous phase are mixed with a micromixer, that is, hydrogen and By mixing the mixed gas of oxygen with the acidic aqueous solution, a slag flow in which the gas phase and the liquid phase from the outlet of the mixer are alternately formed is formed, and the slag flow is used to synthesize it inside the reaction tube. Hydrogen peroxide immediately after synthesis can be continuously recovered as hydrogen peroxide water. That is, the slag flow is introduced into a reaction tube coated with a noble metal thin film of a catalyst, and hydrogen peroxide is synthesized in the gas phase and continuously recovered in the liquid phase. In order to generate a stable slag flow, for example, a T-shaped micromixer is preferably used as the micromixer. The gas phase and liquid phase exiting the reaction tube can be appropriately returned to the front of the mixer and circulated. Regarding the volume mixing ratio of hydrogen and oxygen, the stoichiometric ratio of hydrogen peroxide synthesis is hydrogen 5: oxygen 5. However, in order to suppress reduction by hydrogen, which is a side reaction of the following 4, preferably hydrogen 10 to 33% and oxygen 90 to 67%.

The slag flow requires stable continuous supply of the raw material gas phase and the liquid phase and its means, and the volume of the slag flow in the gas phase and liquid phase is determined by the flow rate ratio of both. Therefore, it is preferable to control the flow rate using a mass flow controller for the gas phase and a metering pump for the liquid phase. In addition, the stability of the slag volume is maintained because the inner diameter of the flow path does not change, so the gas phase inlet inner diameter, liquid phase inlet inner diameter, mixer outlet inner diameter, reaction tube inner diameter, reaction tube inner diameter does not change, It is important that these diameters are constant. If these diameters are constant, the slag volume is stably maintained.

In the reaction system for direct continuous synthesis of hydrogen peroxide according to the present invention, the reduction reaction with hydrogen, which is the side reaction 4 described below, is performed when the oxygen ratio (oxygen / hydrogen) in the raw material gas is excessive (1 or less). Therefore, it is desirable to ensure a condition with an oxygen ratio of 1.6 or more, preferably 2.0 or more.

In the direct continuous synthesis of hydrogen peroxide, the following reactions 1 to 4 occur.
1: H ₂ + O ₂ → H ₂ O ₂ (target reaction: synthesis of H ₂ O ₂ )
2: H ₂ + 1 / 2O ₂ → H ₂ O (side reaction: combustion by oxidation)
3: H ₂ O ₂ → H ₂ O + 1 / 2O ₂ (side reaction: decomposition of H ₂ O ₂ )
4: H ₂ O ₂ + H ₂ → H ₂ O (side reaction: reduction with hydrogen)

The acidic aqueous solution preferably contains one or more inorganic acids selected from hydrochloric acid, sulfuric acid, phosphoric acid and the like. For example, a saturated aqueous solution of carbon dioxide containing one or more inorganic acids can be used. When an inorganic acid is used, the pH of the aqueous solution is 1 to 4, preferably 2 to 3. Furthermore, the synthesis efficiency of hydrogen peroxide can be increased by adding at least one of fluorine, chlorine, bromine and iodine to the acidic aqueous solution. Any of the substances preferably has a total concentration in an acidic aqueous solution in the range of 0.01 to 100 mg / L.

The mixer is not particularly limited, such as a micro mixer, a T-shaped mixer, a static mixer, a swirl mixer, and a multi-laminar flow contact type mixer, but a slag in which a gas phase gas and a liquid phase liquid phase alternately continue When the flow is stably generated, it is preferable to use a T-shaped mixer or a T-shaped mixer micromixer. The volume mixing ratio of gas and liquid is gas 100: liquid 1, preferably 5 to 50: liquid 1, more preferably gas 5 to 10: liquid 1.

The reaction temperature is preferably in the range of 0 to 80 ° C., more preferably in the range of 5 to 50 ° C. Since hydrogen peroxide is synthesized from hydrogen and oxygen gas, in order to increase the concentration of the synthesized hydrogen peroxide, it is required to increase the gas density. It is not preferable.

The reaction pressure is an especially important factor in increasing the gas density, and high pressure conditions are preferable for increasing the concentration of synthesized hydrogen peroxide. However, from the viewpoint of safe industrialization, ultrahigh pressure is avoided, and the reaction pressure is preferably adjusted to a range of 0.1 to 50 MPa, particularly 0.1 to 20 MPa.

The reaction time is controlled by the sum of the diameter and length of the reaction tube and the supply flow rate of the gas phase and aqueous solution phase. In this case, it is possible to employ a process in which the aqueous solution phase is circulated until the concentration of the target hydrogen peroxide solution is reached.

The reaction tube coated with the catalyst noble metal thin film can be preferably produced by a method in which the inner wall of the reaction tube is coated with the catalyst noble metal thin film by electroless plating. As a method for producing a reaction tube in which a noble metal thin film is coated by electroless plating, the method described in the literature (Japanese Patent No. 4986174) can be applied. Palladium, noble metal alloys mainly composed of palladium, such as palladium, alloys of palladium and gold, those in which gold nanoparticles are deposited on the surface of a palladium thin film, alloys of palladium and silver, porous palladium films, etc. In particular, in the presence of gold, the hydrogen conversion rate can be improved.

Further, in the electroless plating method, for example, when a 2 μm-thick palladium film is coated on a hollow thin tube having an inner diameter of 0.5 mm × 1000 mm constituting the reaction tube, 37 mg of palladium is used. However, this amount is considerably smaller than 1 g of 5% Pd-supported activated carbon (Pd: 50 mg). Further, as the reaction tube, a reaction tube in which a hollow fiber bundled in parallel is coated with a noble metal thin film of a catalyst by electroless plating can be used, whereby the reaction tube can be scaled up.

Next, an apparatus for continuously directly synthesizing hydrogen peroxide from hydrogen and oxygen will be described. The apparatus for directly synthesizing hydrogen peroxide according to the present invention includes a reaction tube having a hollow tube inner wall coated with a noble metal thin film and the reaction tube. A means for supplying a raw material gas hydrogen, an oxygen or air gas phase, a means for supplying an aqueous phase, and a hydrogen peroxide immediately after synthesis synthesized inside the reaction tube by water or an acid aqueous solution. And a means for collecting.
In the present invention, a reaction tube in which a noble metal thin film is coated by electroless plating can be used as the reaction tube.
The apparatus preferably includes, for example, a reaction tube in which a noble metal thin film is coated on the inner wall of the tube by electroless plating, such as palladium, an alloy of palladium and gold, an alloy of palladium and silver, and a porous membrane of palladium. An apparatus including a reaction tube covered with a thin film made of any one or more of them is used.

In the above apparatus, preferably, as the hollow tube, for example, a stainless tube, an Inconel tube, a Hastelloy tube, a titanium tube, a corrosion-resistant tube selected from the above, or an internal titanium lining, a stainless tube, an Inconel tube A device using any one of the corrosion-resistant double pipes selected from Hastelloy pipes is used. In the above apparatus, the flow path entering the reaction tube includes a mixer that forms a slag flow in which the phase states of the raw material gas phase and the aqueous phase are alternately continued, and the mixer that mixes the raw material gas and the recovered water. The inner diameter of the outflow part, the inner diameter of the reaction tube, and the inner diameter of the reaction tube joint are the same, and the hydrogen peroxide synthesized inside the reaction tube is continuously recovered as hydrogen peroxide with water or an acid aqueous solution. The provision of the means is a preferred embodiment.

Further, the apparatus includes a mass flow controller for controlling the supply of the raw material gas phase, a metering pump for controlling the supply of the water phase, and a micro gas for mixing the raw material gas phase and the water phase downstream of the mass flow controller and the metering pump. A mixer was installed to generate a slag flow in which the phase state of the raw material gas phase and the aqueous phase were alternately continued, and a stable slag flow was produced using a T-shaped micromixer for the micromixer. A preferred embodiment is that it is generated and that a recirculation means for recirculating the recovered aqueous phase from the reaction tube to the reaction tube is provided.

Next, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 shows a basic concept of hydrogen peroxide synthesis and hydrogen peroxide recovery in a hollow thin tube whose inner wall is coated with a catalyst noble metal thin film. This is because the raw material gas (hydrogen and oxygen or air, or hydrogen and oxygen and inert gas) and the recovered water become, for example, a slag flow in which the gas and liquid phase states are alternately continued by a mixer. Shows that the hydrogen peroxide synthesis reaction proceeds with the catalyst of the noble metal thin film coated on the inner wall of the tube, and the synthesized hydrogen peroxide is recovered before being decomposed in the recovered water portion immediately after. is there.

FIG. 1 is a flow diagram of a hydrogen peroxide direct synthesis apparatus that synthesizes hydrogen peroxide continuously from hydrogen and oxygen, and shows an example of an apparatus that implements the direct hydrogen peroxide synthesis method of the present invention. It is.

The symbols in the figure indicate the means shown below. That is, the symbols are: B-1: hydrogen gas cylinder, B-2: air gas cylinder, B-3: oxygen gas cylinder, R-1 to 3: pressure reducing valve, MFC-1 to 3: mass flow controller, V-1 to 3 : Stop valve, CV-1 to 5: Check valve, SV-1 to 2: Safety valve, P1 to 3: Pressure gauge, AT-1: Recovery liquid (acid aqueous solution) tank, BV-1: Ball valve, LP- 1: Metering liquid supply pump, M-1: mixer, T-1 to 2: thermometer, CR-1: catalytic reaction tube, S-1: gas-liquid separator, NV-1: needle valve, BPR1-2: A back pressure valve, MFM-1: mass flow meter, and G-1: gas collection bag are shown. 1 is submerged in the water tank, and the reaction temperature is controlled by controlling the temperature of the water in the water tank with a constant temperature circulator.

The hydrogen peroxide direct synthesis apparatus and its operation will be described in detail.
The source gases, hydrogen and oxygen, are supplied from separate high-pressure gas cylinders (B-1 to 2) and reduced to a predetermined pressure by the pressure reducing valves (R-1 to 3), and then the mass flow controllers (MFC1 to 3). ) To adjust to a predetermined gas flow rate.

At this time, the flow rate ratio of hydrogen to oxygen may theoretically be hydrogen 5: oxygen 5, but oxygen can be added excessively. In order to further improve safety, it is possible to change the gas cylinder of B-2 to an inert gas such as nitrogen or carbon dioxide if necessary. The raw material gas mixed at a predetermined flow rate is heated to a predetermined temperature in the water tank and then introduced into the mixer (M-1).

On the other hand, the recovered aqueous phase for quickly recovering the hydrogen peroxide synthesized in the reaction tube into the aqueous phase is supplied from the recovered liquid tank (AT-1) to the suction of the metered liquid supply pump (LP-1). . The recovered liquid is heated to a predetermined temperature in the water tank and then introduced into the mixer (M-1) in the same manner as the raw material gas. The recovered water used here may be pure water, but for the purpose of improving the yield and selectivity of the synthesized hydrogen peroxide by re-decomposition and reaction, sulfuric acid, phosphoric acid, hydrochloric acid and other acids are used. Addition and addition of fluoride ions, chloride ions, bromide ions, iodide ions, and the like can be performed.

The mixer (M-1) is, for example, a T-shaped mixer or a Y-shaped mixer for the purpose of forming a slag flow in which the phase states of the raw material gas phase and the recovered water aqueous phase are alternately continued. It is done. In order to form a stable slag flow, the flow rate of the raw material gas is controlled by a mass flow controller so that it is 10 times or less, preferably 5 times or less of the recovered water amount, and the recovered liquid is controlled by a metering pump. To do. The raw material gas and the recovered liquid are supplied to the catalyst reaction tube (CR-1) in the state of a slag flow in which the gas phase and the water phase alternately and continuously flow. Next, the raw material gas is converted into hydrogen peroxide by the action of the noble metal catalyst coated on the inner wall of the reaction tube, and is quickly recovered in the aqueous phase immediately after the gas phase to become hydrogen peroxide solution. It is collected and stored in the separator (S-1).

Regarding the conditions of the synthesis reaction in the hydrogen peroxide direct synthesizer, the reaction temperature is preferably set to 0 to 80 ° C., more preferably 5 to 50 ° C. The reaction pressure is preferably set in the range of 0.1 to 50 MPa, more preferably in the range of 0.1 to 20 MPa. The reaction time depends on the inner diameter of the reaction tube, but when the inner diameter is 1 mm, it is set within 2 minutes, preferably within 1 minute.

The inner diameter of the reaction tube used here is preferably set to 10 mm or less in order to stably form a slag flow. Further, from the viewpoint of safety, the hydrogen extinguishing diameter is preferably 1 mm or less. Set to. As the noble metal catalyst, for example, palladium, an alloy of palladium and gold, a material in which gold nanoparticles are deposited on the surface of a palladium thin film, an alloy of palladium and silver, or a porous film of palladium is preferably used.

In order to increase the concentration of hydrogen peroxide in the recovered liquid, the needle valve (NV-1) at the outlet of the gas-liquid separator (S-1) is closed, and the recovered liquid tank (AT-1) is removed from the circulation line (CL-1). It is also possible to arrange a circulation line for returning the recovered liquid to (). However, since the noble metal that is a hydrogen peroxide synthesis catalyst also acts as a decomposition catalyst for the synthesized hydrogen peroxide, it is necessary to pay attention to its circulation. It is also possible to arrange a line for recirculating the gas after the reaction, and this can be carried out as appropriate in consideration of the conversion rate of the reaction gas.

The following effects are exhibited by the present invention.
(1) By using the hydrogen peroxide direct synthesis technology of the present invention, it is possible to achieve a reduction in the amount of catalyst used, which was a problem of the known technology.
(2) By using a reaction tube coated with a noble metal thin film of the catalyst by electroless plating, etc., the surface of the noble metal effective as a catalyst can be formed from a thin film of micron order, and sufficient surface of the catalyst necessary for the reaction is secured. However, the amount of expensive noble metal used can be reduced.

(3) By using a hydrogen peroxide direct synthesis device equipped with a tube-shaped reaction field, the load resistance due to mass transfer is reduced, reaction runaway in the reaction field is eliminated, and hydrogen peroxide is uniformly synthesized. It is possible.

(4) A method in which a mixed gas of hydrogen and oxygen is divided into a slag flow in which an aqueous solution is alternately phased, or a method in which hydrogen or oxygen is mixed with an aqueous solution in advance and supplied to the reaction field, or Safety of direct synthesis of hydrogen peroxide can be ensured by any method of simultaneously supplying nitrogen or carbon dioxide as the active gas.
(5) By using a hollow thin tube having an inner diameter of 1 mm or less as the reaction tube, it is possible to realize the concept of so-called extinguishing diameter, thereby suppressing the explosion of the mixed gas of hydrogen and oxygen.

(6) By using a tube-shaped reaction field with low load resistance due to mass transfer, it is possible to prevent the synthesized hydrogen peroxide from re-contacting and decomposing to the catalyst, and by a continuous flow reaction. The productivity of the target product can be dramatically improved.

(7) Currently, hydrogen peroxide that is distributed in the market inevitably contains organic substances derived from the manufacturing method, but according to the present invention, ultra-high purity hydrogen peroxide for semiconductors with strict purity requirements, Organic substance-free hydrogen peroxide as a reagent for microanalysis can be produced and provided.

A flow diagram of a hydrogen peroxide direct synthesis apparatus that continuously synthesizes hydrogen peroxide directly from hydrogen and oxygen is shown. The visualization flow figure for verifying stabilization of the flow state of slag flow is shown. The result of the density | concentration of the synthetic | combination hydrogen peroxide of Example 1 is shown. The results of hydrogen conversion, hydrogen peroxide selectivity, and hydrogen peroxide yield during the synthesis of hydrogen peroxide in Example 1 are shown. The result of the density | concentration of the synthesized hydrogen peroxide of Example 2 is shown. The results of hydrogen conversion, hydrogen peroxide selectivity, and hydrogen peroxide yield during the synthesis of hydrogen peroxide in Example 1 are shown. The connection form of the PFA visualization tube for verifying the stabilization of the flow state of the slag flow is shown.

Next, the present invention will be specifically described based on production examples and examples, but the present invention is not limited to the following production examples and examples.

Production Example 1
(Formation of palladium seed nuclei on the inner wall of a titanium-lined nickel alloy tube reaction tube)
(1) Manufacture of titanium-lined nickel alloy tube reaction tube As the material of the outer tube of the double tube composed of the outer tube and the inner tube, Inconel 625 (trade name) of nickel alloy is used, and as the material of the inner tube, Titanium-lined nickel alloy tube consisting of a double tube of hollow thin tubes with a hollow portion by using pure titanium, inserting a pure titanium inner tube inside a nickel alloy outer tube, rolling and fitting A reaction tube was manufactured. A stainless steel tube and a Hastelloy tube to which an inner surface titanium lining was applied were similarly manufactured by the same method.

(2) Oxidation treatment of titanium surface 0.3 wt% peroxidation in the presence of supercritical water under high temperature and high pressure conditions (500 ° C., 30 MPa) from the inlet of the titanium-lined nickel alloy tube reaction tube composed of the above double tube Hydrogen water was supplied. Oxygen decomposed from the hydrogen peroxide forms a homogeneous phase with supercritical water to create a good oxidizing environment, which oxidizes the surface of pure titanium in the inner tube and forms a uniform titanium oxide film. Thus, a titanium oxide layer having a thickness of about 100 μm was formed.

The resulting titanium-lined nickel alloy tube reaction tube consisting of a double tube composed of nickel alloy-pure titanium-titanium oxide has an inner diameter of 1 mm, an outer diameter of 1.5 mm, a length of 100 cm, and an inner surface area. It was 31.4 cm ² .

(3) Introduction of silane coupling agent Silane coupling agent for fixing palladium and titanium oxide to a titanium-lined nickel alloy tube reaction tube composed of a double tube composed of the above nickel alloy-pure titanium-titanium oxide. As a solution, 1% 3-trimethoxysilylpropyldiethylenetriamine dissolved in toluene was introduced and held at 70 ° C. for 16 hours in a sealed state.

(4) Formation of palladium seed nuclei As a pretreatment for electroless plating, a titanium-lined nickel alloy tube reaction tube composed of a double tube composed of the above nickel alloy-pure titanium-titanium oxide is subjected to palladium on its titanium oxide surface. A seed seed was attached. Specifically, 5 ml of a 0.1 M palladium acetate aqueous solution is passed through the inner wall of the reaction tube to be adsorbed, and further 5 ml of a 1 M hydrazine aqueous solution is passed through it to seed palladium particles on the inner wall surface. As precipitated.

Production Example 2
(Electroless plating of palladium on the inner wall of a titanium-lined nickel alloy tube reaction tube)
The hollow-tubular titanium-lined nickel alloy tube reaction tube with the seeds of palladium particles produced in the production example 1 was immersed in a water bath at 60 ° C., and 4 mM [Pd (NH ₃ ) ₄ ] Cl ₂ , 50 ° C. plating solution containing 0.15 M EDTA, 1M ammonia 10 mM hydrazine was passed at a flow rate of 0.5 ml per minute, and 200 ml of plating solution was supplied. The liquid was stopped.

During the flow, the plating solution flowing out from the end of the tube was collected, and the amount of palladium contained in the flowing plating solution was analyzed by ICP emission spectroscopy. As a result, the amount of palladium consumed was 57 mg, which was plated on the surface of the inner wall of the tube. Palladium with an initial concentration of 380 ppm decreased to 10 ppm or less and flowed out. As a result of SEM observation of the cross section of the tube, the thickness of the palladium layer was 3.5 μm.

Production Example 3
(Electroless plating of palladium and silver on the inner wall of a titanium-lined nickel alloy tube reaction tube)
The hollow tube titanium-lined nickel alloy tube reaction tube with a seed of palladium particles produced in the process of Production Example 1 is immersed in a 60 ° C. water bath, and 9 mM acetic acid is used as a plating solution from the tip of the tube of the hollow tube. An aqueous solution at 60 ° C. containing palladium, 1 mM silver nitrate, 0.15 M EDTA, 4 M ammonia and 10 mM hydrazine was passed at a flow rate of 0.5 ml per minute.

The composition of the plating solution in this case was such that the ratio of palladium to silver was 90:10 by mass ratio. After 110 ml of the plating solution was passed through the tip of the hollow thin tube, it was washed with water. The plating solution flowing out from the end of the tube was collected, and the amounts of palladium and silver contained in the flowing plating were analyzed by ICP emission spectroscopy. As a result, the amount of palladium consumed and the amount of silver were 67.7 mg and 10.1 mg, respectively, and these were plated on the inner wall of the tube. These corresponded to 87% and 13% in mass ratio, respectively.

Production Example 4
(Formation of porous palladium membrane by selective elution removal of silver)
4M nitric acid was added to a titanium-lined nickel alloy tube reaction tube of a hollow thin tube coated with 67.7 mg (87% by mass): 10.1 mg (13% by mass) of palladium and silver produced in the step of Production Example 3. 700 ml was passed at 25 ° C. at a flow rate of 0.5 ml per minute, and silver was selectively eluted and removed to form a porous palladium membrane. The amount of eluted palladium and silver was analyzed by ICP emission spectroscopy. As a result, the remaining palladium was 48.1 mg (94% by mass), and silver was 2.9 mg (5.7% by mass).

Production Example 5
(Formation of an alloy film of palladium and silver by heat treatment)
A hollow thin tube titanium-lined nickel alloy tube reaction tube coated with 67.7 mg (87% by mass): 10.1 mg (13% by mass) of palladium and silver produced in the process of Production Example 3 has an inner diameter of 4 cm. It was inserted into a quartz tube and the whole was placed in a tubular furnace. While flowing hydrogen from one end of the hollow thin tube, it was heated at 600 ° C. for 3 hours to form an alloy film of palladium and silver. Although X-ray diffraction peaks of palladium (2θ = 40.0 °) and silver (2θ = 38 °) were observed before heating, a new peak (2θ = 39.5) of an alloy film of palladium and silver was observed after the heating. °) was observed.

Example 1
(Description of direct synthesizer)
The direct synthesis of hydrogen peroxide was performed using the direct synthesizer shown in FIG. The direct synthesis apparatus of FIG. 1 will be described. The apparatus shown in the dotted line in FIG. 1 was submerged in a water tank for ensuring safety and controlling the reaction temperature. The synthesis temperature of hydrogen peroxide was set to 40 ° C., the reaction pressure was set to 0.8 MPa with a pressure gauge (PT; P-1, P-2, P-3), and back pressure valves (BPR-1, BPR-2) ) To control. In addition, a liquid circulation line (CL-1) is installed in the direct synthesizer so that the synthesized hydrogen peroxide solution can be circulated.

The source gas used for the synthesis of hydrogen peroxide is hydrogen cylinder (B-1), air cylinder (B-2), and oxygen cylinder (B-3) if necessary. The supply amount of the raw material gas was controlled by the mass flow controller (MFC; MFC-1, MFC-2, MFC-3). As a result, the composition of the raw material gas can be arbitrarily set and supplied quantitatively. The aqueous acid solution used for the recovery of hydrogen peroxide is an aqueous solution of 0.02 mol / L sulfuric acid and 26 ppm sodium bromide. The aqueous acid solution is charged in advance in an acid aqueous solution tank (Acid tank; AT-1) and pump (LP-1 ).

(Direct synthesis of hydrogen peroxide from hydrogen, oxygen and air 1)
The direct synthesis apparatus shown in FIG. 1 was used, and the hydrogen concentration in the raw material gas used for the synthesis of hydrogen peroxide was 21.4 vol%. The oxygen concentration was changed to 1, 1.6, and 2.0 at an oxygen ratio (oxygen / hydrogen) using air and oxygen. In any condition, the composition of the raw material gas containing 30 vol% or more of nitrogen, which is an inert gas, was used.

In the synthesis and recovery of hydrogen peroxide, the total supply amount of the raw material gas is 7 ml / min (0.8 MPa, 40 ° C.), and the supply amount of the acid aqueous solution (0.02 mol / L sulfuric acid and bromine 20 ppm added) is 1 ml / min. It was. Before these were directly introduced into the reaction tube of the synthesizer, the raw material gas and the acid aqueous solution were mixed with a 1/8 inch T-shaped mixer of the mixer. The raw material gas and the acid aqueous solution are supplied to the reaction tube by forming a slag flow in which the gaseous gas phase and the liquid aqueous phase are alternately continued. After the synthesis and recovery are performed continuously, the reaction is performed. I let it flow out of the tube. The residual gas and aqueous acid solution after the reaction were separated by a gas-liquid separator (S-1). The synthesized hydrogen peroxide together with the acid aqueous solution is collected in a gas-liquid separator (Separator; S-1), and the residual gas is collected as a back pressure valve (BPR-1) and a mass flow meter (MFM; MFM-1). And collected in a gas bag (G-1).

In the direct synthesis apparatus shown in FIG. 1, a reaction tube coated with electroless plating of a palladium single layer was used as a synthesis catalyst. The reaction time was 64 seconds. The reaction tube was 2 m × 5 and 10 m, and the outer diameter of the reaction tube was 1/8 inch, similar to the gas-liquid mixing T-shaped mixer. The inner diameter of the union of the reaction tube joint for connecting the reaction tubes was made the same as the inner diameter of the reaction tube to prevent the slag flow phase state from being disturbed by the change of the inner diameter.

After collecting the acid aqueous solution collected in the gas-liquid separator (S-1), the concentration of hydrogen peroxide synthesized by iodine coulometric titration (hydrogen peroxide counter HP-300, manufactured by Hiranuma Sangyo Co., Ltd.) Was quantified. The residual gas collected in the gas bag (G-1) was analyzed by TCD gas chromatography (manufactured by Shimadzu Corporation, GC-8A) to determine the hydrogen conversion rate.

As a result, the concentration of the synthesized hydrogen peroxide was 10940 ppm under the conditions of 21.4 vol% hydrogen and 42.9 vol% oxygen. The hydrogen conversion rate under these conditions is 95.7%, and the hydrogen peroxide selectivity is 63.6%. Yield = hydrogen conversion × hydrogen peroxide selectivity / 100 The hydrogen peroxide yield determined in (1) was 60.9%.

Example 2
(Direct synthesis of hydrogen peroxide from hydrogen, air and oxygen 2)
1 was used under the same conditions as in Example 1 except that the composition of the raw material gas was changed from a hydrogen concentration of 13.6 vol% and an oxygen ratio of 0.5 to 4.0 using the direct synthesis apparatus of FIG. Was synthesized.

The concentration of the synthesized hydrogen peroxide increases as the oxygen concentration in the raw material gas increases. When the oxygen ratio (oxygen / hydrogen) in the raw material gas is less than 2, as the oxygen ratio decreases, The selectivity dropped sharply. When the oxygen ratio was 2 or more, the selectivity for hydrogen peroxide slightly increased as the oxygen ratio increased.

Example 3
(Increase in hydrogen peroxide concentration by circulation of synthesized hydrogen peroxide solution)
1 was used under the same conditions as in Example 1 except that the composition of the raw material gas was changed to 13.6 vol% hydrogen and 86.4% air (oxygen / hydrogen = 1.3). Hydrogen oxide was synthesized (one cycle). Subsequently, the synthesized hydrogen peroxide obtained here was recovered, charged into an acid aqueous solution tank (AT-1), and synthesized under the same conditions as in one cycle, only an acid aqueous solution was obtained in one cycle. Hydrogen peroxide was synthesized (two cycles) by a method of circulating the synthesized hydrogen peroxide instead of the hydrogen peroxide solution.

In one cycle, the concentration of synthesized hydrogen peroxide was 4903 ppm, and in 2 cycles it was 7710 ppm. From this, it was confirmed that the concentration of the synthesized hydrogen peroxide can be increased by circulating only the synthesized hydrogen peroxide solution.

Example 4
(Stabilization of slag flow)
In order to verify the stabilization of the flow state of the slag flow in which the gas phase and the water phase are alternately continued, an experiment was performed with the visualization flow shown in FIG. 2 using a PFA visualization tube (PFA Tube). .
A 1/8 inch T-shaped mixer (M-2) is used as a mixer (Mixer) for mixing the gas and water of the raw material gas and water, and a 1/8 inch PFA visualization tube (PFA Tube, PFA Tube, (Inner diameter; 1.6 mm) was connected. Connect this 1 / 8-inch PFA visualization tube every 2 m with a straight union (Union; U-1, inner diameter; 2.3 mm) of the reaction tube joint, and use a straight union with a total length of 10 m. Two types of tubes having a length of 10 m were prepared.

A gas-liquid separator (Separator; S-2) is connected to the outlet of the PFA visualization tube, and only the gas is discharged out of the system via the back pressure valve (BPR; BPR-3), and the liquid is the gas-liquid separator. To accumulate. First, the entire apparatus was pressurized with air (Ar), and the pressure of the entire apparatus was maintained at 0.8 MPa with a back pressure valve (BPR-3) while the air was circulated. In order to make visualization easier, add colored food and supply colored water at 1 ml / min, and change the air supply rate to 1.2 ml / min, 2 ml / min, 6 ml / min, and 12 ml / min. The flow state of the slag flow was observed and confirmed with each of the tube connected with the straight union and the seamless tube without the union.

In both the tube connected by the straight union described above and the seamless tube, a stable slag flow was discharged to the PFA visualization tube. The liquids coalesced and the uniform segment (segment) collapsed. On the other hand, in the tube not provided with the union, the size of the inlet segment was held up to the outlet 10 m ahead. From this result, in order to maintain the continuity of the flow state of the slag flow, it was shown that it is essential to keep the inner diameter of the pipe constant.

As described above in detail, the present invention relates to a method and apparatus for continuous direct synthesis and recovery of hydrogen peroxide using a catalyst-coated reaction tube, and by using a reaction tube coated with a noble metal thin film of a catalyst. The surface of the noble metal effective as a catalyst can be formed from a micron-order thin film, and the amount of expensive noble metal used can be reduced while sufficiently securing the surface of the catalyst necessary for the reaction. In the hydrogen peroxide direct synthesis apparatus of the present invention, by using a tube-shaped reaction field, load resistance due to mass transfer is reduced, reaction runaway in the reaction field is eliminated, and uniform synthesis reaction is possible. In the present invention, a mixed gas of hydrogen and oxygen is divided into an alternating continuous slag flow with an aqueous solution, a method in which hydrogen or oxygen is mixed with an aqueous solution in advance and supplied to a reaction field, and nitrogen or dioxide as an inert gas. It is possible to ensure the safety of the direct synthesis of hydrogen peroxide by any method of simultaneously supplying carbon. The present invention uses a catalyst-coated reaction tube in which a hollow tube inner wall is coated with a catalyst noble metal thin film to directly and continuously synthesize hydrogen peroxide from hydrogen and oxygen. The present invention is useful for providing a new method and apparatus for continuously recovering hydrogen oxide water.

B: Gas cylinder (B-1; hydrogen, B-2; air, B-3; oxygen, B-4; nitrogen)
R: cylinder regulator MFC: mass flow controller (MFC-1, MFC-2, MFC-3, MFC-4)
V: Valve (V-1, V-2, V-3, V-4)
CV: Check valve (CV-1, CV-2, CV-3, CV-4, CV-5, CV-6, CV-7)
PT: Pressure gauge (P-1, P-2, P-3, P-4)
SV: Safety valve (SV-1, SV-2)
AT-1: Acid tank; Acid aqueous solution tank BV-1: Ball valve LP: Liquid pump (LP-1, LP-2)
TI: Thermometer (T-1, T-2)
CR-1: Catalytic reactor; Palladium-catalyzed reaction tube S: Gas-liquid separator (Separator; S-1, S-2)
NV: Needle valve (NV-1)
BPR: Back pressure valve (BPR-1, BPR-2, BPR-3)
MFM: Mass Flow Meter (MFM-1)
G-1: Gas bag M: T-shaped mixer (Mixer; M-1, M2)
WT-1: Water tank
Union: Straight Union (U-1)
CL-1: Circulation line

Claims (31)

1. A method of directly synthesizing hydrogen peroxide from hydrogen and oxygen,
   Using a reaction tube in which a hollow tube inner wall is coated with a noble metal thin film, a raw material gas hydrogen, an oxygen or air gas phase, and a reaction medium aqueous phase are supplied to a flow path inside the reaction tube, Under the reaction temperature and reaction pressure conditions, hydrogen peroxide is continuously synthesized directly from hydrogen and oxygen inside the reaction tube, and the synthesized hydrogen peroxide is continuously recovered as hydrogen peroxide water. Direct synthesis method of hydrogen peroxide.
2. The reaction tube is coated with a thin film composed of at least one of palladium, an alloy of palladium and gold, a palladium thin film with gold nanoparticles deposited thereon, an alloy of palladium and silver, and a porous palladium film. The method for directly synthesizing hydrogen peroxide according to claim 1, wherein a reaction tube is used.
3. The method for directly synthesizing hydrogen peroxide according to claim 1, wherein a reaction tube in which the noble metal thin film of the reaction tube is coated by electroless plating is used.
4. 4. The method for directly synthesizing hydrogen peroxide according to claim 1, wherein the noble metal thin film has a thickness in a range of 0.5 to 2 μm.
5. The hollow tube was selected from a stainless steel tube, an Inconel tube, a Hastelloy tube, a corrosion-resistant tube selected from a stainless steel tube, an Inconel tube, a Hastelloy tube, a titanium tube, or a stainless steel tube, an Inconel tube, a Hastelloy tube, which has been subjected to internal titanium lining. The method for directly synthesizing hydrogen peroxide according to any one of claims 1 to 4, wherein any one of corrosion-resistant double pipes is used.
6. The method for directly synthesizing hydrogen peroxide according to any one of claims 1 to 4, wherein a fumed silica tube is used as the hollow tube.
7. As the reaction tube, a thin film made of at least one of palladium, an alloy of palladium and gold, a material in which gold nanoparticles are deposited on the surface of a palladium thin film, an alloy of palladium and silver, and a porous film of palladium is used as a reaction tube. 6. The direct hydrogen peroxide film according to claim 5, wherein a metal oxide film serving as a base is produced by high-temperature oxidation at 600 ° C. or higher, or supercritical water oxidation at 374 ° C. or higher when the electrode is produced by electroless plating. Synthesis method.
8. The method for directly synthesizing hydrogen peroxide according to any one of claims 1 to 7, wherein the inner diameter of the reaction tube is 10 mm or less, 0.05 mm or more, or 5 mm or less and 0.1 mm or more.
9. The reaction temperature is in the range of 0 to 80 ° C, or in the range of 5 to 50 ° C, and the reaction pressure is in the range of 0.1 to 50 MPa, or in the range of 0.1 to 20 MPa. 9. The method for directly synthesizing hydrogen peroxide according to any one of 1 to 8.
10. The method for directly synthesizing hydrogen peroxide according to any one of claims 1 to 9, wherein the hydrogen peroxide synthesized inside the reaction tube is continuously recovered as hydrogen peroxide water with water or an aqueous acid solution.
11. The water or acid aqueous solution for recovering the hydrogen peroxide synthesized inside the reaction tube contains one or more kinds of ions selected from fluoride ion, chloride ion, bromide ion, and iodide ion. Method for direct synthesis of hydrogen peroxide.
12. The acidic aqueous solution contains at least one substance selected from fluorine, chlorine, bromine, and iodine, and all the substances have a total concentration in the acidic aqueous solution in the range of 0.01 to 100 mg / L. 11. The method for directly synthesizing hydrogen peroxide according to 11.
13. When continuously recovering the hydrogen peroxide synthesized in the reaction tube, the gas in the raw material gas phase and the liquid in the aqueous phase are mixed with a mixer, and the volume flow rate ratio is adjusted. A slag flow in which the phase state of the aqueous phase is alternately continued is formed, and using the slag flow, hydrogen peroxide immediately after synthesis synthesized inside the reaction tube is continuously recovered as a hydrogen peroxide solution. The method for directly synthesizing hydrogen peroxide according to claim 10 or 11.
14. The volume mixing ratio of gas and liquid is gas 5 to 50: liquid 1, and the volume flow rate ratio of the raw material gas phase and the recovered water phase is set to 50 or less with respect to the water phase 1 or to the water phase 1. The method for directly synthesizing hydrogen peroxide according to claim 13, wherein a slag flow is formed with a gas phase of 10 or less. *
15. The outflow part inside diameter of the mixer that mixes the gas in the raw material gas phase and the liquid in the water phase, the reaction pipe inside diameter and the reaction pipe joint inside diameter are the same diameter, and the slag flow size is not changed by the flow path. 14. The method for directly synthesizing hydrogen peroxide according to 14.
16. By using a mass flow controller for the raw material gas phase and using a metering pump for the aqueous phase, and controlling the flow rate and discharge pressure of each, while mixing the gas of the raw material gas phase and the liquid of the aqueous phase with a micromixer The method for directly synthesizing hydrogen peroxide according to any one of claims 13 to 15, wherein a slag flow is generated.
17. The method for directly synthesizing hydrogen peroxide according to any one of claims 13 to 16, wherein a stable slag flow is generated using a T-shaped micromixer as the micromixer.
18. The volume mixing ratio of hydrogen and oxygen is 10 to 33% hydrogen and 90 to 67% oxygen, and the ratio of oxygen to hydrogen (oxygen / hydrogen) in the source gas phase is 1.6 or more, or oxygen and hydrogen The method for directly synthesizing hydrogen peroxide according to any one of claims 1 to 13, wherein the ratio of is set to 2.0 or more.
19. The method for directly synthesizing hydrogen peroxide according to any one of claims 10 to 18, wherein the recovered aqueous phase from the reaction tube is recycled to the reaction tube.
20. An apparatus for continuously synthesizing hydrogen peroxide from hydrogen and oxygen directly,
    A reaction tube in which the inner wall of a hollow tube is coated with a noble metal thin film, a means for supplying hydrogen as a raw material gas and a gas phase of oxygen or air, a means for supplying a water phase of a reaction medium, and a reaction tube An apparatus for directly synthesizing hydrogen peroxide, comprising means for continuously recovering hydrogen peroxide synthesized immediately after synthesis with water or an aqueous acid solution.
21. As a reaction tube in which a noble metal thin film is coated on the inner wall of the tube by electroless plating, the reaction is coated with a thin film composed of at least one of palladium, an alloy of palladium and gold, an alloy of palladium and silver, and a porous film of palladium. 21. The apparatus for directly synthesizing hydrogen peroxide according to claim 20, comprising a tube.
22. 21. The apparatus for directly synthesizing hydrogen peroxide according to claim 20, wherein a reaction tube in which the noble metal thin film of the reaction tube is coated by electroless plating is used.
23. The hollow tube was selected from a stainless steel tube, an Inconel tube, a Hastelloy tube, a corrosion-resistant tube selected from a stainless steel tube, an Inconel tube, a Hastelloy tube, a titanium tube, or a stainless steel tube, an Inconel tube, a Hastelloy tube, which has been subjected to internal titanium lining. The apparatus for directly synthesizing hydrogen peroxide according to any one of claims 20 to 22, wherein any one of corrosion-resistant double pipes is used.
24. The direct synthesis apparatus for hydrogen peroxide according to any one of claims 20 to 22, wherein a fumed silica tube is used as the hollow tube.
25. As the reaction tube, a thin film made of at least one of palladium, an alloy of palladium and gold, a material in which gold nanoparticles are deposited on the surface of a palladium thin film, an alloy of palladium and silver, and a porous film of palladium is used as a reaction tube. 24. The metal oxide film used as a base when produced by electroless plating inside, using a high-temperature oxidation of 600 ° C. or higher or a supercritical water oxidation method of 374 ° C. or higher. Hydrogen peroxide direct synthesizer.
26. The hydrogen peroxide solution according to any one of claims 20 to 25, further comprising a mixer that forms a slag flow in which a phase state of a raw material gas phase and an aqueous phase are alternately continued in a flow path entering the reaction tube. Direct synthesizer.
27. 25. The hydrogen peroxide solution according to any one of claims 20 to 24, wherein an inner diameter of an outlet of the mixer for mixing the raw material gas and the recovered water, an inner diameter of the reaction tube, and an inner diameter of the reaction tube joint are the same. Direct synthesizer.
28. The hydrogen peroxide synthesized directly according to any one of claims 20 to 27, comprising means for continuously recovering hydrogen peroxide synthesized inside the reaction tube as hydrogen peroxide water with water or an acid aqueous solution. Synthesizer.
29. A mass flow controller for controlling the supply of the raw material gas phase, a metering pump for controlling the supply of the aqueous phase, and a micromixer for mixing the raw material gas phase and the aqueous phase are arranged downstream of the mass flow controller and the metering pump. The hydrogen peroxide direct synthesis apparatus according to any one of claims 20 to 28, wherein a slag flow in which a phase state of a raw material gas phase and an aqueous phase are alternately continued is generated.
30. 30. The apparatus for directly synthesizing hydrogen peroxide according to any one of claims 26 to 29, wherein a T-shaped micromixer is used as the micromixer to generate a stable slag flow.
31. 30. The apparatus for directly synthesizing hydrogen peroxide according to any one of claims 20 to 29, further comprising recirculation means for recirculating the recovered aqueous phase discharged from the reaction tube to the reaction tube.

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