TW201441145A - 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

Continuous direct synthesis and recovery method and device for hydrogen peroxide using catalyst-coated reaction tube

The present invention relates to a continuous direct synthesis, recovery method and apparatus for hydrogen peroxide using a catalyst-coated reaction tube, and more particularly to coating a noble metal film of a catalyst by a non-electrolytic plating in a hollow tube. A reaction tube made of a wall, a direct synthesis method of hydrogen peroxide by continuously synthesizing hydrogen peroxide from hydrogen and oxygen, and a direct synthesis method and apparatus for continuously recovering hydrogen peroxide directly from hydrogen peroxide as hydrogen peroxide. In the present specification, a reaction tube in which a noble metal thin film of a catalyst is coated on a hollow inner wall is described as a catalyst-coated reaction tube.

The hydrogen peroxide-based oxidizing agent which reacts with the material to be treated and which has a low environmental load, is widely used in fields such as water treatment, sterilization, bleaching, washing, and the like, particularly in the field of semiconductor cleaning. At present, almost all of the hydrogen peroxide circulating in the market is gradually oxidized by the hydrazine of aromatic organic compounds. The reduction method (蒽醌 method) is synthesized. This method is a multi-stage reaction, and has been accused of environmental pollution problems caused by the use of a large amount of organic reagents, organic solvents, and the like.

On the other hand, a process for directly synthesizing hydrogen peroxide from hydrogen and oxygen is expected to be a simple synthesis process with a small environmental load. Further, for the direct synthesis, various precious metal catalysts and the like are used, and a method of directly synthesizing hydrogen peroxide from hydrogen and oxygen has been reviewed based on various viewpoints.

The most important technical issue for the direct synthesis of hydrogen peroxide from hydrogen and oxygen is the safe treatment of a mixture of hydrogen and oxygen, the so-called explosive gas. Further, as a subject of industrialization of the technology, it is important to ensure the production amount of hydrogen peroxide, increase the concentration, and reduce the amount of expensive precious metal catalyst used. In recent years, various technologies have been developed or proposed to overcome such problems. In recent years, as a prior art, for example, a mixed gas of hydrogen, oxygen, and nitrogen has been continuously supplied to a metal catalyst colloidal dispersion liquid. A direct synthesis method in which hydrogen peroxide is accumulated in a liquid (Reference 1).

This method achieves high safety by using nitrogen to ensure the safety of direct synthesis of hydrogen peroxide, and by continuously introducing a mixed gas of a material gas into a fixed liquid. However, since this method is a batch type, there is a problem that it is difficult to ensure the production amount, and it is necessary to recover the metal catalyst colloid from the synthesis of hydrogen peroxide water, and there is a problem that the generated hydrogen peroxide is decomposed and the like.

As for other prior art, when continuous synthesis of hydrogen peroxide has been proposed, liquid (water), hydrogen, oxygen, and nitrogen of the gas are simultaneously supplied to the solid catalyst filled in the column, and the column is used to fill the solid touch. A method for continuously synthesizing hydrogen peroxide by a medium (Reference 2).

In this way, the liquid can be made to flow on the surface of the solid catalyst particles, so that the gas forms a continuous phase, and the peroxidation is ensured by a continuous process. The production of hydrogen. However, in order to ensure safety, it is necessary to increase the introduction amount of the inert gas. Therefore, in this method, the amount of hydrogen and oxygen involved in the synthesis is reduced, and the synthesized hydrogen peroxide is again likely to be decomposed by contact with the catalyst, and the amount of catalyst used is increased by filling the catalyst in the column. Large, increased load resistance due to material movement in the column.

Further, as other prior art, a continuous synthesis method in which a solid catalyst is filled in a microchannel having a fine channel is also proposed (Reference 3). In this method, by using the microchannel to ensure the hydrogen flame-extinguishing distance and simultaneously supplying the gas and the liquid, the water of the reaction site promotes the extension of the flame-extinguishing distance, thereby ensuring safety. However, this method may increase the load resistance when the material moves, the catalyst surface of the reaction site, the liquid phase, and the reactivity control in the gas phase three phases due to the filling of the catalytic metal particles in the microchannel. problem.

In the prior art, the heterogeneous catalyst used for direct synthesis includes, for example, a single metal particle, an alloy particle, and various catalytic species such as an activated carbon or a metal oxide supporting catalyst and a metal complex modifying catalyst. In the above, various catalysts such as Pd, Pt, Au, PdO, and Pd/C, Pd/Al ₂ O ₃ or the like which are metals are proposed (for example, cited documents 4 to 6). However, in order to increase the specific surface area, any one of the catalysts has a problem that it must be used as fine particles or colloids.

These methods use a filled solid catalyst. However, in general, the direct synthesis of hydrogen peroxide is based on the decomposition catalyst of hydrogen peroxide, the risk of explosion due to the continuous phase of hydrogen and oxygen, and the reduction of load resistance when the substance moves. In terms of opinion, think The application of filled solid catalysts is not very good.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1]: JP-A-2007-84372

[Patent Document 2]: Japanese Patent Publication No. 6-183703

[Patent Document 3]: WO2010/044271

[Patent Document 4]: Japanese Laid-Open Patent Publication No. Hei 5-213607

[Patent Document 5]: Japanese Patent Publication No. 2004-516921

[Patent Document 6]: Japanese Patent Laid-Open No. 51-4097

In the above-mentioned prior art, the inventors of the present invention have actively studied the results of solving the above problems of the prior art in view of the above-mentioned prior art, and found that the noble metal film of the catalyst is coated on the hollow tube by electroless plating. The reaction tube made of the inner wall can ensure the smooth movement of the material, and can form a better or even optimum three-phase interface formed by the catalyst surface, the liquid phase and the gas phase. Further, the present inventors have found that by continuously forming a slug flow by alternately interacting the gas phase of the gas with the phase of the liquid phase of the liquid, the mixture of hydrogen and oxygen of the explosive gas is separated by the liquid, thereby ensuring The safety of direct synthesis of hydrogen peroxide is further repeated and the present invention has been completed.

SUMMARY OF THE INVENTION The object of the present invention is to provide a clean, safe and industrially processable process for the manufacture of hydrogen peroxide which can replace the previous energy-consumption type and environmental pollution possibility. That is, the object of the present invention is to establish a method for forming a preferred three-phase interface formed by a catalyst surface, a liquid phase, a gas phase, and a direct synthesis of hydrogen peroxide from hydrogen and oxygen, thereby providing a reduction. A direct synthesis method and apparatus for industrially produced hydrogen peroxide that can safely and stably operate while ensuring the productivity of the target product while using the expensive precious metal catalyst.

In order to solve the above problems, the present invention is constituted by the following technical means.

(1) A direct synthesis method of hydrogen peroxide, which is a method for directly synthesizing hydrogen peroxide from hydrogen and oxygen, which is characterized in that a reaction tube for coating a noble metal film on an inner wall of a hollow tube is used to hydrogen and oxygen of a raw material gas. Or the gas phase of the air and the aqueous phase of the reaction medium are supplied to the flow path inside the reaction tube, and hydrogen peroxide is continuously and directly synthesized from hydrogen and oxygen in the reaction tube under a specific reaction temperature and reaction pressure. And the synthesized hydrogen peroxide is continuously recovered as hydrogen peroxide water.

(2) The method for directly synthesizing hydrogen peroxide according to the above (1), wherein the reaction tube is made of an alloy of palladium, palladium and gold, and the gold nanoparticles are deposited on the surface of the palladium film. A reaction tube coated with a film of any one or more of an alloy of palladium and silver and a porous film of palladium.

(3) The direct synthesis method of hydrogen peroxide according to (1) above, wherein the noble metal film using the reaction tube is a reaction tube coated by electroless plating.

(4) The direct synthesis method of hydrogen peroxide according to (1) or (3) above, wherein the film thickness of the noble metal film is in the range of 0.5 to 2 μm.

(5) The direct synthesis method of hydrogen peroxide according to any one of the above (1) to (4), wherein the hollow tube is made of a stainless steel tube, an Inconel tube, and Hester The alloy (Hastelloy) tube, the corrosion-resistant tube selected from the titanium tube, or the corrosion-resistant double tube selected from the stainless steel tube, the inconel tube, and the Herst alloy tube coated with the inner titanium liner.

(6) A method for directly synthesizing hydrogen peroxide according to any one of the above (1) to (4), wherein a fumed silicate tube is used as the hollow tube system.

(7) The method for directly synthesizing hydrogen peroxide according to the above (5), wherein as the reaction tube, an alloy of palladium, palladium and gold is produced in the inside of the reaction tube by electroless plating, and the carbon nanocrystal is made. When the particles are deposited on the surface of a palladium film, a film of any one of palladium and silver, or a porous film of palladium, it is oxidized at a high temperature of 600 ° C or higher or supercritical water at 374 ° C or higher. The method is to produce an oxide film which is a metal of a base.

(8) The direct synthesis method of hydrogen peroxide according to any one of (1) to (7), wherein the inner diameter of the reaction tube is 10 mm or less And 0.05 mm or more, or 5 mm or less and 0.1 mm or more.

(9) The direct synthesis method of hydrogen peroxide according to any one of the above (1) to (8), wherein 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 0.1 The range of 50 MPa or the range of 0.1-20 MPa.

(10) The direct synthesis method of hydrogen peroxide according to any one of (1) to (9) above, wherein the hydrogen peroxide synthesized in the inside of the reaction tube is treated with hydrogen peroxide water by water or an aqueous acid solution. Continuous recycling.

(11) The direct synthesis method of hydrogen peroxide according to (10) above, wherein the water or acid aqueous solution recovered from hydrogen peroxide synthesized inside the reaction tube contains fluoride ions, chloride ions, bromide ions, Any one or more ions of iodide ions.

(12) The method for directly synthesizing hydrogen peroxide according to the above (11), wherein the acidic aqueous solution contains at least one of fluorine, chlorine, bromine and iodine, and the total concentration of any substance in the acidic aqueous solution is The range of 0.01~100mg/L.

(13) A direct synthesis method of hydrogen peroxide according to the above (10) or (11), wherein, when the hydrogen peroxide synthesized in the inside of the reaction tube is continuously recovered, the gas and the aqueous phase of the raw material gas phase are mixed by a mixer. The liquid, and by adjusting its volumetric flow ratio, the phase of the raw material gas phase and the aqueous phase alternately form a plug flow, and the plug flow is used to synthesize the newly synthesized hydrogen peroxide to be peroxidized inside the reaction tube. Hydrogen water is continuously recovered.

(14) The direct synthesis method of hydrogen peroxide according to (13) above, wherein a volume mixing ratio of the gas to the liquid is 5 to 50: liquid 1, The volume flow ratio of the raw material gas phase to the recovered aqueous phase is set to 50 or less with respect to the aqueous phase 1 gas phase, or 10 or less with respect to the aqueous phase 1 gas phase to form a plug flow.

(15) The direct synthesis method of hydrogen peroxide according to (13) or (14) above, wherein the inner diameter of the outflow portion of the mixer in which the gas of the raw material gas phase and the liquid of the aqueous phase are mixed is set in the reaction tube The diameter and the diameter of the reaction tube joint are the same diameter, and the flow size is not changed by the flow path.

(16) A direct synthesis method of hydrogen peroxide according to any one of the above (13) to (15), wherein a mass flow controller is used in the raw material gas phase and a quantitative amount is used in the aqueous phase. The pump controls the respective flow rates and the discharge pressures, and the liquid mixture of the gas and the water phase of the raw material gas phase is mixed by the micro mixer to generate a plug flow.

(17) The direct synthesis method of hydrogen peroxide according to any one of (13) to (16) above, wherein the micromixer uses a T-type micro mixer to generate a stable plug flow.

(18) The direct synthesis method of hydrogen peroxide according to any one of the above (1) to (13), wherein a volume mixing ratio of hydrogen to oxygen is 10 to 33% of hydrogen and 90 to 67% of oxygen, and The ratio of oxygen to hydrogen (oxygen/hydrogen) in the raw material gas phase is 1.6 or more, or the ratio of oxygen to hydrogen is 2.0 or more.

(19) A direct synthesis method of hydrogen peroxide according to any one of the above (10) to (18), wherein the recovered aqueous phase from the reaction tube is recycled to the reaction tube.

(20) A direct synthesizing device for hydrogen peroxide, which is a device for continuously synthesizing hydrogen peroxide by direct hydrogen and oxygen, and is characterized by: a reaction tube coated with a noble metal film on the inner wall of the hollow tube, means for supplying a gas phase of hydrogen of the material gas and oxygen or air to the reaction tube, means for supplying the aqueous phase of the reaction medium, and using water or an aqueous acid solution The hydrogen peroxide which has been synthesized in the inside of the reaction tube is continuously recovered.

(21) The apparatus for directly synthesizing hydrogen peroxide according to the above (20), wherein the reaction tube which coats the noble metal thin film on the inner wall of the tube by electroless plating includes an alloy of palladium, palladium and gold, and palladium. A reaction tube coated with a film formed of any one of a silver alloy and a porous film of palladium.

(22) The apparatus for directly synthesizing hydrogen peroxide according to the above (20), wherein the noble metal film using the reaction tube is a reaction tube coated by electroless plating.

(23) The apparatus for directly synthesizing hydrogen peroxide according to any one of (20) to (22), wherein the hollow tube is made of a stainless steel tube, a nichrome tube, a Herstite tube, or Any one of the corrosion-resistant tubes selected from the titanium tube or the corrosion-resistant double tube selected from the stainless steel tube, the inconel tube, and the Herstle alloy tube with the inner titanium liner.

(24) The apparatus for directly synthesizing hydrogen peroxide according to any one of (20) to (22), wherein the hollow tube system is a fumed cerium oxide tube.

(25) The apparatus for directly synthesizing hydrogen peroxide according to the above (23), wherein the reaction tube is used to form an alloy of palladium, palladium, and gold by electroless plating in the inside of the reaction tube to make the carbon nano When the particles are deposited on a surface of a palladium film, a film of a palladium-silver alloy or a porous film of palladium, the oxide film of the metal to be a base is provided. It is manufactured by high temperature oxidation at 600 ° C or higher or supercritical water oxidation at 374 ° C or higher.

(26) The apparatus for directly synthesizing hydrogen peroxide according to any one of (20) to (25), wherein the flow path entering the reaction tube is formed such that the phase of the raw material gas phase and the aqueous phase are alternately continuous. Plug flow mixer.

(27) The direct synthesizing apparatus for hydrogen peroxide according to any one of (20) to (24), wherein an inner diameter of the outflow portion of the mixer in which the raw material gas and the recovered water are mixed, an inner diameter of the reaction tube, and a reaction tube The inner diameter of the joint is the same diameter.

(28) The apparatus for directly synthesizing hydrogen peroxide according to any one of the above aspects (20) to (27), comprising hydrogen peroxide using water or an aqueous acid solution synthesized in the inside of the reaction tube, and hydrogen peroxide water A means of continuous recycling.

(29) The apparatus for directly synthesizing hydrogen peroxide according to any one of (20) to (28), further comprising: a mass flow controller that controls supply of a raw material gas phase; and a quantitative pump that controls supply of the aqueous phase; Further, downstream of the mass flow controller and the quantitative pump, a micro-mixer for mixing the raw material gas phase and the water phase is disposed so that the phase of the raw material gas phase and the aqueous phase are continuously continuous to generate a plug flow.

(30) The apparatus for directly synthesizing hydrogen peroxide according to any one of (26) to (29), wherein the micromixer uses a T-type micro mixer to generate a stable plug flow.

(31) Peroxygen as described in any one of the above (20) to (29) A direct synthesis apparatus for hydrogenation, which comprises means for recycling a recycled aqueous phase flowing out of the reaction tube to the reaction tube.

Next, the present invention will be described in more detail.

The present invention provides a reaction tube formed by coating a noble metal film on the inner wall of a hollow tube, in which hydrogen peroxide is continuously and directly synthesized from hydrogen and oxygen, and the synthesized hydrogen peroxide is hydrogen peroxide. A direct synthesis method and apparatus for hydrogen peroxide continuously recovered from water.

The reaction tube used in the present invention is a hollow reaction tube, that is, a tubular hollow tube, and the inner space of the hollow tube preferably widens the coated area of the noble metal film. In order to increase the ratio of area to volume, a hollow capillary tube having an inner diameter of 0.05 mm to 10 mm is used as the reaction tube system. 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 or thermal diffusion inside the hollow capillary tube, it is preferable that the inner diameter of the reaction tube is 1 mm or less and 0.1 mm or more. When considering the pressure loss, it should be 0.25mm or more.

Further, the length of the hollow capillary tube constituting the reaction tube is an important factor for determining the contact time of the noble metal film with the catalyst in the reaction. Accordingly, the longer the length of the hollow thin tube, the higher the conversion efficiency of hydrogen, but when it is too long, there is a possibility that the synthesized hydrogen peroxide is decomposed again. In addition, the longer the length of the hollow thin tube, the greater the pressure loss, so the preferred or even the optimum length is selected. Specifically, since the volume varies depending on the inner diameter of the reaction tube to be used, even if the hollow thin tubes constituting the reaction tube have the same length reaction time (gas average residence time), the length cannot be determined.

In addition, since the inner area (catalyst coated area) / volume (specific surface area) changes with the inner diameter, even if the same volume (same reaction time), the reaction result varies with the inner diameter, so it is selected. The preferred or even optimum reaction time for each inner diameter, that is, the length of the hollow capillary. When the inner diameter is set to 1 mm, the reaction time is selected to be within 2 minutes, preferably within 1 minute.

The coating of the noble metal film of the catalyst on the inner surface of the hollow capillary tube constituting the reaction tube can be applied to an electroless plating method which can be easily realized by introducing a plating solution into the hollow capillary tube. This electroless plating method is also excellent in that the thickness of the plating film can be controlled by the concentration of the plating solution and the amount of the liquid to be applied. This electroless plating method has the advantage that the metal thin film can be coated when the material of the hollow thin tube constituting the reaction tube is a metal and a surface of a non-conductive glass, ceramic, plastic or the like.

The material of the tubular hollow thin tube constituting the reaction tube used in the present invention can preferably utilize, for example, a metal, an alloy, a glass, a ceramic, a plastic or the like. The metallic hollow pipe is made of corrosion-resistant titanium, a nickel alloy, a chromium alloy, or an iron alloy. In addition, in order to improve the chemical resistance, the use of titanium or titanium alloy is used. The hollow tube can preferably utilize, for example, a corrosion-resistant tube selected from a stainless steel tube, a Inconel tube, a Hertzite tube, a titanium tube, or a stainless steel tube or a inconel tube coated with an inner titanium liner. , Hester alloy tube, fuming cerium oxide tube, etc.

When the titanium or titanium alloy is attached, it is preferred to carry out the decane coupling treatment as the treatment before the electroless plating. At this time, it is preferred to subject the surface of the titanium to oxidation treatment. The oxidation treatment of the titanium surface is preferably performed by a temperature higher than 600 ° C Oxidation treatment, or supercritical water oxidation treatment above 374 ° C, to form a strong oxide film.

As a separate preferred material, a glass dioxide system uses a cerium oxide glass siphon for use in a column of a gas chromatograph, a ceramic system uses a tube of alumina, titania, zirconia, etc., and a plastic system uses polypropylene, polyethylene, A tube of polyamine or the like.

In the present invention, any one or more of palladium, an alloy of palladium and gold, a gold nanoparticle deposited on the surface of a palladium film, an alloy of palladium and silver, and a porous film of palladium are used as the reaction tube system. A reaction tube covered with a film. The coating of the noble metal film of the catalyst for the inner wall of the tubular hollow tube constituting the reaction tube is applied to the inner core of the tube to impart a seed nucleus of palladium, and then the plating solution containing the misform forming agent, the noble metal salt and the reducing agent is passed through the liquid. The inside of the hollow capillary tube is achieved by electroless plating. The electroless plating solution to be used may be a metal salt of palladium, silver, platinum, rhodium or the like, or a metal complex thereof, a miscible forming agent which is stably dissolved therein, and a reducing agent dissolved in a suitable solvent. .

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

In the present invention, the hydrogen phase of the hydrogen of the source gas, the gas phase of the oxygen or the air, and the aqueous phase of the reaction medium are supplied to the flow path inside the reaction tube, and the inside of the reaction tube is under the specific reaction temperature and reaction pressure. hydrogen Hydrogen peroxide is directly synthesized directly with oxygen. In this case, it is preferred to control the respective gas flow rates of the raw material gas phase and the water phase, and to mix the gas of the raw material gas phase with the water phase by a micromixer, that is, by mixing a gas of hydrogen and oxygen. Mixing with the acidic aqueous solution to continuously form a plug flow from the phase of the gas phase and the liquid phase from the outlet of the mixer, and using the plug flow, the newly synthesized hydrogen peroxide can be synthesized as hydrogen peroxide water inside the reaction tube. It is continuously recovered. That is, the plug flow is introduced into a reaction tube of a noble metal thin film coated with a catalyst, and hydrogen peroxide is synthesized in a vapor phase, and is continuously recovered in a liquid phase. In order to stably generate a plug flow, for example, a micro mixer uses a T-type micro mixer. The gas phase and liquid phase leaving the reaction tube can also be properly circulated before returning to the mixer. Regarding the volume mixing ratio of hydrogen to oxygen, the stoichiometric ratio of hydrogen peroxide synthesis is hydrogen 5: oxygen 5, but in order to suppress the reduction by hydrogen caused by the following four side reactions, it is preferably 10 to 33% of hydrogen. Oxygen 90~67%.

The plug flow is important in the continuous supply of the raw material gas phase and the liquid phase stability, and the volume of the gas phase and the liquid phase of the plug flow is determined according to the flow ratio of the two. Therefore, it is better to use the mass flow controller in the gas phase, and the liquid phase preferably uses a metering pump to control the flow rate. Moreover, since the stability of the plug flow volume is maintained by not changing the inner diameter of the flow path, the inner diameter of the gas phase inlet, the inner diameter of the liquid phase inlet, the inner diameter of the outlet of the mixer, the inner diameter of the reaction tube, and the reaction are not allowed. It is important that the inner diameter of the pipe joint changes so that the inner diameters are constant. If the inner diameters are constant, the plug flow volume can be stably maintained.

In the reaction system of direct continuous synthesis of hydrogen peroxide of the present invention, the reduction reaction due to hydrogen of the fourth side reaction described below is due to the raw material gas The oxygen ratio (oxygen/hydrogen) in the body becomes remarkable under the condition of an excess of hydrogen (1 or less), so it is preferable to ensure an oxygen ratio of 1.6 or more, preferably 2.0 or more.

The direct continuous synthesis of hydrogen peroxide produces the following reactions 1 to 4.

1:H ₂ +O ₂ →H ₂ O ₂ (destination reaction: synthesis of H ₂ O ₂ )

2: H ₂ + 1/2 O ₂ → H ₂ O (side reaction: combustion by oxidation)

3: H ₂ O ₂ → H ₂ O + 1/2 O ₂ (side reaction: decomposition of H ₂ O ₂ )

4: H ₂ O ₂ + H ₂ → H ₂ O (side reaction: reduction by hydrogen)

The acidic aqueous solution preferably contains at least one inorganic acid selected from the group consisting of hydrochloric acid, sulfuric acid, phosphoric acid, and the like. For example, a saturated aqueous solution containing one or more kinds of the above-mentioned inorganic acid carbon dioxide can be used. When a mineral acid is used, the pH of the aqueous solution is from 1 to 4, preferably from 2 to 3. Further, by adding any one of fluorine, chlorine, bromine and iodine to the acidic aqueous solution, the synthesis efficiency of hydrogen peroxide can be improved. The total concentration of any of the substances in the acidic aqueous solution is preferably in the range of 0.01 to 100 mg/L.

The mixer is a micro mixer, a T-type mixer, a static mixer, a swirl mixer, a multi-thin laminar flow contact type mixer, etc., and is not particularly limited, but a gas and a liquid phase in a gas phase are provided. When the phase state of the liquid is stable to produce a continuous continuous plug flow, it is preferred to use a micro mixer of a T-type mixer or a T-type mixer. The volume mixing ratio of the gas to the liquid is gas 10: liquid 1, preferably gas 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 a gas of hydrogen and oxygen, When the synthesized hydrogen peroxide is highly concentrated, it is required to increase the gas density, and based on this, the reaction under high temperature conditions is not good.

The reaction pressure is an important factor in increasing the gas density, and when the hydrogen peroxide to be synthesized is highly concentrated, it is preferably under high pressure. However, based on the industrial viewpoint of safety, the ultra-high pressure system is far away, and the reaction pressure is preferably adjusted to a range of 0.1 to 50 MPa, and particularly preferably to a range of 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 the aqueous phase. In this case, a process of circulating the aqueous phase until the desired concentration of hydrogen peroxide water is reached can be employed.

The reaction tube coated with the noble metal thin film of the catalyst can be preferably produced by coating the noble metal thin film of the catalyst on the inner wall of the reaction tube by electroless plating. The method described in the literature (Japanese Patent No. 4986174) can be applied as a method for producing a reaction tube in which a noble metal film is coated by electroless plating. The precious metal plating may be exemplified by palladium, an alloy of palladium and gold, a precipitate of gold nanoparticles on the surface of a palladium film, an alloy of palladium and silver, a porous film of palladium, or the like. To be effective, in particular, the conversion rate of hydrogen can be increased in the presence of gold.

Further, in the electroless plating method, for example, when palladium having a thickness of 2 μm is entirely coated on a hollow capillary tube having an inner diameter of 0.5 mm × 100 mm, which is a reaction tube, 37 mg of palladium is used. However, this is also a relatively small amount compared to 1 g of activated carbon (Pd: 50 mg) carrying 5% Pd. Also, a noble metal coated with a catalyst by electrolytic plating of the hollow fibers arranged in a bundle may be used. The reaction tube of the film serves as a reaction tube, whereby the scale of the reaction tube can be enlarged.

Next, the apparatus for directly synthesizing hydrogen peroxide from hydrogen and oxygen will be described. The direct synthesizing apparatus for hydrogen peroxide according to the present invention is characterized by comprising a reaction tube coated with a noble metal thin film on the inner wall of a hollow tube, and a raw material. A means for supplying a gas of hydrogen gas with oxygen or air to the reaction tube, means for supplying the water phase, and means for continuously recovering the hydrogen peroxide which has been synthesized in the reaction tube by using water or an aqueous acid solution.

In the present invention, a reaction tube in which a noble metal thin film is coated by electroless plating can be used as the above reaction tube.

Further, in the above apparatus, for example, a reaction tube having a film coating of any one or more of palladium, an alloy of palladium and gold, an alloy of palladium and silver, or a porous film of palladium is preferably used as the noble metal film by electroless plating. A device for covering a reaction tube formed on the inner wall of a tube.

The above device preferably uses, for example, a stainless steel tube, a nichrome tube, a Herstle alloy tube, a corrosion-resistant tube selected from a titanium tube, or a stainless steel tube, a nichrome tube, a Hessite tube coated with an inner titanium liner. Any one of the corrosion-resistant double tubes selected from the alloy tubes is used as a device for the hollow tube. In addition, a preferred embodiment of the above apparatus is provided with a mixer which continuously forms a plug flow in a flow path entering the reaction tube so that the phase of the raw material gas phase and the aqueous phase alternately form a plug flow, and the mixer of the mixed raw material gas and the recovered water flows out. The inner diameter of the portion, the inner diameter of the reaction tube, and the inner diameter of the reaction tube joint are the same diameter, and a means for continuously recovering hydrogen peroxide synthesized inside the reaction tube by water or an aqueous acid solution with hydrogen peroxide water.

Furthermore, in a preferred embodiment of the apparatus, a mass flow controller for controlling the supply of the material gas phase and a metering pump for controlling the supply of the water phase are provided, and are disposed downstream of the mass flow controller and the metering pump. There is a micro-mixer that mixes the raw material gas phase with the water phase, so that the phase state of the raw material gas phase and the water phase are alternately continuous to generate a plug flow, and the micro-mixer uses a T-shaped micro mixer to generate a stable plug. The stream is provided with a recycling means for recycling the recovered aqueous phase flowing out of the reaction tube to the reaction tube.

Next, a preferred embodiment of the present invention will be specifically described with reference to the accompanying drawings.

Fig. 1 is a view showing the basic concept of hydrogen peroxide synthesis and hydrogen peroxide recovery in a hollow capillary tube of a noble metal thin film coated with a catalyst. This shows that the raw material gas (hydrogen, oxygen or air, or hydrogen and oxygen and inert gas) and the recovered water are continuously plugged into a plug flow by, for example, a kneading machine, and the raw material gas is partially covered by the tube. The catalyst of the noble metal film on the inner wall undergoes a hydrogen peroxide synthesis reaction, so that the hydrogen peroxide synthesized here is directly recovered as recovered water before being decomposed.

Fig. 1 is a flow chart showing a direct synthesis apparatus for hydrogen peroxide which directly synthesizes hydrogen peroxide from hydrogen and oxygen, and shows an example of a device for realizing the direct synthesis of hydrogen peroxide of the present invention.

The symbols in the figures represent the means shown below. That is, the symbol indicates B-1: gas cylinder, B-2: air gas cylinder, B-3: oxygen gas cylinder, R-1~3: pressure reducing valve, MFC-1~3 : mass flow controller, V-1~3: shut-off valve, CV-1~5: check valve, SV-1~2: safety valve, P-1~3: pressure gauge, AT-1: recovery liquid (acid aqueous solution) tank, BV-1: ball valve, LP-1: dosing liquid supply pump, M-1: mixer, T-1~2: thermometer, CR-1: catalyst reaction tube, S-1 : gas-liquid separator, NV-1: needle valve, BPR-1~2: back pressure valve, MFM-1: mass flow meter, G-1: gas collection bag. In addition, the means in the dotted line of Fig. 1 is controlled by water in the water tank to control the temperature of the water in the water tank by a constant temperature circulating machine to control the reaction temperature.

The direct synthesis apparatus of the above hydrogen peroxide and its operation will be described in detail.

The hydrogen and oxygen of the material gas are supplied from the high-pressure gas cylinders (B-1 to 2), and are decompressed to a specific pressure by the pressure reducing valve (R-1 to 3), and then adjusted by the mass flow controller (MFC1 to 3). To a specific gas flow.

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

On the other hand, the recovered aqueous phase for rapidly recovering the hydrogen peroxide synthesized in the reaction tube in the aqueous phase is supplied from the recovery liquid tank (AT-1) to the suction end of the dosing liquid supply pump (LP-1). . After the recovered liquid was heated to a specific temperature in the water tank, it was introduced into a mixer (M-1) in the same manner as the material gas. The recovered water used herein may be pure water, but may be added with an acid such as sulfuric acid or phosphoric acid, hydrochloric acid, or fluoride for the purpose of improving the yield or selectivity of the re-decomposition or reaction of the synthesized hydrogen peroxide. Addition of ions, chloride ions, bromide ions, iodide ions, and the like.

The mixer (M-1) uses, for example, a T-shaped mixer or a Y-shaped mixer when the plug phase is continuously formed by alternately forming the phase of the raw material gas phase and the aqueous phase of the recovered water. In the case of forming a stable plug flow, the flow rate of the raw material gas is controlled to 10 times or less, preferably 5 times or less, preferably by a mass flow controller, and the recovery liquid is controlled by a metering pump. The material gas and the recovery liquid are supplied to the catalyst reaction tube (CR-1) in a state in which the phase of the gas phase and the phase of the water phase alternately flow. Then, the raw material gas is converted into hydrogen peroxide by the action of a noble metal catalyst coated on the inner wall of the tube of the reaction tube, and the gas phase is quickly recovered by the subsequent aqueous phase to become hydrogen peroxide water and separated by gas and liquid. (S-1) is recovered and stored.

Regarding the synthesis reaction conditions in the direct synthesis apparatus for hydrogen peroxide described above, the reaction temperature is preferably set to 0 to 80 ° C, more preferably 5 to 50 ° C. The reaction pressure is preferably set to a range of from 0.1 to 50 MPa, more preferably from 0.1 to 20 MPa. The reaction time is related to the inner diameter of the reaction tube, and when the inner diameter is 1 mm, it is set to be within 2 minutes, preferably within 1 minute.

The inner diameter of the reaction tube used herein is preferably set to 10 mm or less in order to stably form a plug flow, and is preferably set to be 1 mm or less of the diameter of the hydrogen flame suppression from the viewpoint of safety. As the noble metal catalyst, for example, an alloy of palladium, palladium, and gold, a case where gold nanoparticles are deposited on the surface of a palladium film, an alloy of palladium and silver, and a porous film of palladium are preferably used.

For the purpose of increasing the concentration of hydrogen peroxide in the recovered liquid, the needle valve (NV-1) at the outlet of the gas-liquid separator (S-1) can also be closed and set. The recovery liquid is returned from the circulation line (CL-1) to the circulation line of the recovery liquid tank (AT-1). However, the noble metal of the hydrogen peroxide synthesis catalyst also functions as a decomposition catalyst for the synthesized hydrogen peroxide, so the circulation thereof needs attention. Further, a line for recycling the gas after the reaction may be provided, and may be appropriately carried out in consideration of the conversion ratio of the reaction gas and the like.

According to the present invention, the following effects are exerted.

(1) By the direct synthesis technique of hydrogen peroxide of the present invention, it is possible to reduce the amount of catalyst used for a conventional technical problem.

(2) By using a reaction tube made of a noble metal film coated with a catalyst such as electroless plating, a noble metal surface which is effective as a catalyst can be formed from a micron-sized film, and the catalyst surface required for the reaction can be sufficiently ensured. One side can reduce the amount of expensive precious metals used.

(3) By using a direct synthesizing device of hydrogen peroxide having a tubular reaction site, the load resistance due to the movement of the substance can be reduced, and the reaction of the reaction site is not made drastic, and a uniform synthesis reaction of hydrogen peroxide can be performed.

(4) A method in which a mixed gas of hydrogen and oxygen is separated into a cross-flow in a phase state by an aqueous solution, or a method in which hydrogen or oxygen is previously mixed with an aqueous solution to be supplied to a reaction site, or nitrogen or carbon dioxide is simultaneously supplied as a method Any of the methods of inert gas ensures the safety of direct synthesis of hydrogen peroxide.

(5) Using a hollow capillary tube having an inner diameter of 1 mm or less by a reaction tube system, The concept of the so-called flame elimination diameter can be realized, whereby the explosion of the mixed gas of hydrogen and oxygen can be suppressed.

(6) By using a reaction portion of a tubular shape that reduces the load resistance due to the movement of the substance, the synthesized hydrogen peroxide can be inhibited from recombining with the catalyst and decomposed, and the reaction can be dramatically performed by the continuous flow reaction. Improve the productivity of the target product.

(7) At present, hydrogen peroxide circulated in the market cannot avoid the organic matter containing the source-made method, but the invention can manufacture and provide ultra-high purity hydrogen peroxide for semiconductors with strict purity requirements, or for micro analysis. Test the drug-free hydrogen peroxide.

B‧‧‧ gas cylinders (B-1: hydrogen, B-2: air, B-3: oxygen, B-4: nitrogen)

R‧‧‧Cylinder collection area

MFC‧‧‧Flow Controller (MGC-1, MFC-2, MFC-3, MFC-4)

V‧‧‧ Shutoff Valves (V-1, V-2, V-3, V-4)

CV‧‧‧ check valves (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 Valves (SV-1, SV-2)

AT-1‧‧‧ Acid tank; acid solution tank

BV-1‧‧‧ ball valve

LP‧‧‧Liquid pump (LP-1, LP-2)

TI‧‧‧ Thermometer (T-1, T-2)

CR-1‧‧‧catalyst reaction tube; palladium catalyst 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‧‧‧Flow Meter (MFM-1)

G-1‧‧‧ gas bag

M‧‧‧T-type mixer (Mixer; M-1, M2)

WT-1‧‧‧Sink (Water tank)

Union‧‧‧ Straight Connector (U-1)

CL-1‧‧‧Recycling pipeline

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a flow chart showing a direct synthesizing apparatus for continuously synthesizing hydrogen peroxide by hydrogen and oxygen.

Figure 2 is a flow chart showing the visualization of the stability of the plug flow state.

Figure 3 is a graph showing the results of the synthesis of hydrogen peroxide concentration of Example 1.

Fig. 4 is a graph showing the results of hydrogen conversion rate and hydrogen peroxide selectivity and hydrogen peroxide yield in the hydrogen peroxide synthesis of Example 1.

Figure 5 is a graph showing the results of the synthesis of hydrogen peroxide concentration of Example 2.

Fig. 6 is a graph showing the results of hydrogen conversion rate and hydrogen peroxide selectivity and hydrogen peroxide yield in the hydrogen peroxide synthesis of Example 1.

Figure 7 shows the stabilized PFA used to verify the flow state of the plug flow. Visualize the connection form of the tube.

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

Manufacturing example 1 (Formation of palladium seed nucleus on the inner wall of the reaction tube of nickel-nickel alloy tube with titanium attached) (1) Manufacture of nickel-nickel alloy tube reaction tube with titanium

Inconel 625 (trade name) using a nickel alloy is used as a material other than a double tube composed of an outer tube and an inner tube, and pure titanium is used as a material for the inner tube, and an inner tube made of pure titanium is inserted outside the nickel alloy. On the inner side of the tube, by rolling and fitting, a nickel-nickel alloy tube reaction tube in which titanium is attached by a double tube having a hollow thin tube having a hollow portion is manufactured. The stainless steel tube and the Herstite alloy tube coated with the inner surface titanium can be similarly manufactured by the same method.

(2) Oxidation treatment of titanium surface

In the presence of supercritical water under high temperature and high pressure conditions (500 ° C, 30 MPa), 0.3 wt% of hydrogen peroxide water was supplied from the inlet of the nickel-nickel alloy tube reaction tube in which the double tube was formed. The oxygen decomposed by the hydrogen peroxide forms a uniform phase with the supercritical water to form a good oxidizing environment, whereby the surface of the pure titanium of the inner tube is oxidized to uniformly form a titanium oxide film to form a layer of titanium oxide having a thickness of about 100 μm. .

The inner tube of the nickel-plated nickel alloy tube formed by the double tube composed of the obtained 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 of 31.4 cm ^{2 .} .

(3) Introduction of decane coupling agent

Introducing 3-trimethoxydecylpropyldiethylethylamine into the reaction tube of the nickel-plated nickel alloy tube formed by the double tube composed of the nickel alloy-pure titanium-titanium oxide The decane coupling agent for fixing palladium and titanium oxide was dissolved in toluene, and was kept at 70 ° C for 16 hours.

(4) Formation of palladium species

In the above-mentioned nickel-nickel alloy tubular reaction tube in which titanium is formed by a double tube composed of a nickel alloy-pure titanium-titanium oxide, a seed core of palladium particles is attached to the surface of the titanium oxide as a treatment before electroless plating. . Specifically, 5 ml of an aqueous solution of 0.1 M palladium acetate was passed through the inner wall of the reaction tube, and then 5 ml of a 1 M aqueous solution of hydrazine was passed through to deposit palladium particles as seed nucleus on the inner wall surface.

Manufacturing Example 2 (electroless plating of palladium on the inner wall of the reaction tube of titanium-nickel alloy tube)

The inner nickel-plated nickel alloy tube reaction tube of the hollow thin tube with the palladium particle-coated seed tube prepared in the procedure of the manufacturing example 1 was immersed in a 60 ° C water bath at a flow rate of 0.5 ml per minute from the front end of the tube of the hollow thin tube. The solution containing 4 mM of [Pd(NH ₃ ) ₄ ]Cl ₂ , 0.15 M of EDTA, 1 M of ammonia, and 10 mM of hydrazine in a 50 ° C plating solution was used as a plating solution, and the solution was stopped at the time of supplying 200 ml of the plating solution.

In the liquid passing, the plating solution flowing out from the end of the tube was taken, and the amount of palladium contained in the flowing plating solution was analyzed by ICP emission spectrometry. As a result, the amount of palladium consumed was 57 mg, which was plated on the inner wall surface of the above tube. Palladium having an initial concentration of 380 ppm was reduced to less than 10 ppm and flowed out. As a result of observing the cross section of the above tube by SEM, the thickness of the palladium layer was 3.5 μm.

Manufacturing Example 3 (electroless plating of palladium and silver on the inner wall of the reaction tube of titanium-nickel alloy tube)

The nickel-nickel tube reaction tube in which the titanium-coated hollow tube having the palladium particle-coated seed core prepared in the step of Production Example 1 was immersed in a water bath at 60 ° C, and the flow rate of 0.5 ml per minute from the front end of the tube of the hollow thin tube A 60 ° C aqueous solution containing 9 mM palladium acetate, 1 mM silver nitrate, 0.15 M EDTA, 4 M ammonia, and 10 mM hydrazine was used as a plating solution.

In this case, the composition of the plating solution is a composition of palladium to silver in a mass ratio of 90:10. 110 ml of the plating solution was passed through the front end of the tube of the hollow thin tube, and then washed with water. The plating solution flowing out from the end of the tube was taken, and the amount of palladium and silver contained in the outflow plating solution was analyzed by ICP emission spectrometry. As a result, the amount of palladium consumed and the amount of silver were 67.7 mg and 10.1 mg, respectively, which were plated on the inner wall of the tube. These are equivalent to 87% and 13% by mass ratio, respectively.

Manufacturing Example 4 (Formed by a porous palladium film removed by selective elution of silver)

Prepared in the step of Production Example 3, in a ratio of 67.7 mg (87 mass%): 10.1 mg (13 mass%), coated with a nickel-nickel alloy tube in a hollow thin tube of palladium and silver, at 25 ° C At a flow rate of 0.5 ml per minute, 700 ml of 4 M nitric acid was passed through to selectively remove and remove silver to form a porous palladium membrane. The amount of dissolved palladium and silver was analyzed by ICP emission spectrometry. As a result, residual palladium was 48.1 mg (94% by mass), and silver was 2.9 g (5.7% by mass).

Manufacturing Example 5 (formed by heat-treated palladium and silver alloy film coating)

A nickel alloy tube reaction tube in which a titanium-coated hollow tube was coated with titanium in a ratio of 67.7 mg (87 mass%): 10.1 mg (13 mass%) prepared in the step of Production Example 3 was inserted into an inner diameter of 4 cm. In the quartz tube, the whole is placed in a tubular furnace. Hydrogen was flowed from one end of the tube of the hollow thin tube, and heated at 600 ° C for 3 hours to alloy the film to form a film of an alloy film of palladium and silver. X-ray diffraction peaks of palladium (2θ = 40.0 °) and silver (2θ = 38 °) were observed before heating, and a novel peak (2θ = 39.5 °) of the heated alloy film of palladium and silver was observed.

Example 1 (Description of direct synthesis device)

Direct synthesis of hydrogen peroxide using a direct synthetic assembly as shown in Figure 1. Set it up. The direct synthesizing apparatus of Fig. 1 will be described. To ensure safety and reaction temperature control, the device shown in the dashed line of Figure 1 is flooded with water in the sink. The synthesis temperature of hydrogen peroxide was set to 40 ° C, and the reaction pressure was set to 0.8 MPa with a pressure gauge (PT; P-1, P-2, P-3), and a back pressure valve (BPR-1, BPR) was used. -2) Control. Further, a liquid circulation line (CL-1) is provided in the direct synthesis apparatus, and the synthesized hydrogen peroxide water can also be circulated.

The raw material gas system used in the synthesis of hydrogen peroxide uses a hydrogen cylinder (B-1), an air cylinder (B-2), and an oxygen cylinder (B-3) as needed, and a mass flow controller is disposed on each gas cylinder ( MFC; MFC-1, MFC-2, MFC-3), controlling the supply of raw material gases. Thereby, the composition of the material gas can be arbitrarily set and quantitatively supplied. The aqueous acid solution used for the recovery of hydrogen peroxide is an aqueous solution of 0.02 mol/L of sulfuric acid and 26 ppm of sodium bromide. The aqueous acid solution is previously fed into an acid solution tank (Acid tank; AT-1) to pump (LP-1). ) Quantitative supply.

(Direct synthesis of hydrogen peroxide from hydrogen, oxygen and air 1)

The hydrogen concentration in the material gas used for the synthesis of hydrogen peroxide was 21.4 vol% using the direct synthesis apparatus shown in Fig. 1 . The oxygen concentration was changed to 1, 1.6, and 2.0 in terms of oxygen ratio (oxygen/hydrogen) using air and oxygen. Under any conditions, it is composed of a raw material gas of nitrogen containing 30 vol% or more of an inert gas.

The synthesis and recovery of hydrogen peroxide is to set the total supply of raw material gas to 7 ml/min (0.8 MPa, 40 ° C), and an aqueous acid solution (0.02). The supply amount of mol/L sulfuric acid and 20 ppm of bromine was set to 1 ml/min. Before introducing the catalyst into the reaction tube of the direct synthesis apparatus, the raw material gas and the aqueous acid solution were mixed by a 1.8-inch T-type mixer of a mixer. The raw material gas and the aqueous acid solution are supplied to the reaction tube by continuously forming a plug flow in a phase state of the gas phase of the gas and the aqueous phase of the liquid, and are continuously synthesized and recovered, and then flow out from the reaction tube. The residual gas after the reaction is separated from the aqueous acid solution by a gas-liquid separator (S-1). The synthesized hydrogen peroxide is trapped together with the aqueous acid solution in a gas-liquid separator (Separator; S-1), and the residual gas is passed through a back pressure valve (BPR-1) and a mass flow controller (MFM; MFM-1). It was trapped in the gas bag (G-1).

In the direct synthesis apparatus of Fig. 1, a reaction tube coated with electroless plating as a single layer of palladium as a synthesis catalyst was used. The reaction time was set to 64 seconds. The reaction tube was set to 2 m × 5 for 10 m in total, and the outer diameter of the reaction tube was set to 1/8 inch in the same manner as the gas-liquid mixed T-type mixer. The inner diameter of the union of the reaction tube joint for connecting the reaction tube is set to be the same as the inner diameter of the reaction tube, and the phase state of the plug flow due to the change in the inner diameter is prevented from being disturbed.

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

As a result, the hydrogen peroxide concentration synthesized was 10,940 ppm under the conditions of hydrogen of 21.4 vol% and oxygen of 42.0 vol%. Moreover, the hydrogen conversion rate under this condition is 95.7%, and the selectivity of hydrogen peroxide is 63.6%. The hydrogen peroxide yield determined by the formula of the ratio = conversion of hydrogen × selectivity of hydrogen peroxide / 100 was 60.9%.

Example 2 (Direct synthesis of hydrogen peroxide from hydrogen, air and oxygen 2)

The synthesis of hydrogen peroxide was carried out under the same conditions as in Example 1 except that the direct synthesis apparatus of Fig. 1 was used, and the composition of the material gas was changed to a hydrogen concentration of 13.6 vol% and the oxygen ratio was changed from 0.5 to 4.0.

The concentration of hydrogen peroxide synthesized increases as the oxygen concentration in the material gas increases, and the oxygen ratio (oxygen/hydrogen) in the material gas does not reach 2, and as the oxygen ratio decreases, the selectivity of hydrogen peroxide decreases sharply. . When the oxygen ratio is 2 or more, the selectivity of hydrogen peroxide slightly increases as the oxygen ratio increases.

Example 3 (the concentration of hydrogen peroxide increased by the cycle of hydrogen peroxide water synthesized)

The synthesis of hydrogen peroxide was carried out under the same conditions as in Example 1 except that the composition of the material gas was 13.6 vol% of hydrogen and 86.4 vol% of air (oxygen/hydrogen = 1.3). Secondary cycle). Next, the synthetic hydrogen peroxide obtained here is recovered, and it is fed into the acid aqueous solution tank (AT-1), and it is changed to the synthesis of only one cycle of the aqueous acid solution by the same conditions as in the one cycle. The hydrogen peroxide water is subjected to hydrogen peroxide synthesis (2 cycles) by circulating the synthesized hydrogen peroxide.

In one cycle, the synthesized hydrogen peroxide concentration was 4903 ppm, and the second cycle was 7710 ppm. Thus, by merely circulating the synthesized hydrogen peroxide water, it was confirmed that the synthesized hydrogen peroxide concentration can be increased.

Example 4 (The stability of the flow state of the plug flow)

In order to verify the stability of the plug flow state in which the phase of the gas phase and the water phase were continuously connected, the experiment was carried out using the PFA visualization tube (PFA tube) in the visualization flow shown in FIG.

A mixer (Mixer) for gas-liquid mixing of raw material gas and water is a 1.8-inch T-type mixer (M-2), and a 1/8-inch PFA visualization tube is connected to the outlet of the mixer ( PFA tube, inner diameter; 1.6 mm). Prepare the 1/8 inch PFA visualization tube to connect the straight joint (joint; U-1, inner diameter: 2.3 mm) of the reaction tube joint every 2 m so that the total length becomes 10 mm, and the straight line is not used. The type of joint is set to 2 tubes of 10 m.

A gas-liquid separator (Separator; S-2) was connected to the outlet of the PFA visualization tube, and the gas was discharged only outside the system via a back pressure valve (BPR; BPR-3) to accumulate liquid in the gas-liquid separator. Initially, the entire apparatus was pressurized with air (Ar) to circulate the air, and the pressure of the entire apparatus was maintained at 0.8 MPa by a back pressure valve (BPR-3). In a way that is easy to visualize, the colored water added with the food coloring is supplied at 1 mi/min, and the air supply amount is changed to 1.2 ml/min, 2 ml/min, 6 ml/min, and 12 ml/min, respectively, and it is observed that the straight joint is connected. Tube and jointless The seamless flow of the tube.

The above-mentioned tube connected by a straight joint and the tube of the seamless tube in any condition, the PFA visualization tube is sprayed with a stable plug flow, but after passing through the joint which causes the inner diameter of the pipe to change, the air and the liquid are combined to one, so that the uniform The segment (section) collapses. On the other hand, the tube in which the joint is not provided maintains the size of the section of the inlet up to the outlet of the 10m end. From this result, it has been shown that in order to maintain the continuity of the flow state of the plug flow, it is necessary to maintain the inner diameter of the pipe constant.

[Industrial availability]

As described in detail above, the present invention relates to a continuous direct synthesis, recovery method and apparatus for hydrogen peroxide using a catalyst-coated reaction tube, which can be used from a micron-sized film by using a reaction tube of a noble metal film coated with a catalyst. By forming an effective precious metal surface as a catalyst, the amount of expensive precious metal can be reduced while sufficiently ensuring the catalyst surface required for the reaction. The hydrogen peroxide direct synthesis apparatus of the present invention can reduce the load resistance due to the movement of the substance by using the reaction portion of the tube shape, and does not cause a reaction of the reaction site to be intense, and a uniform synthesis reaction can be performed. In the present invention, a method in which a mixed gas of hydrogen and oxygen is separated into an alternate continuous plug flow by an aqueous solution, a method in which hydrogen or oxygen is previously mixed with an aqueous solution and supplied to a reaction site, and a method of simultaneously supplying nitrogen and carbon dioxide as an inert gas is provided. Either method can ensure the safety of direct synthesis of hydrogen peroxide. The invention can be used for providing a catalyst-coated reaction tube for utilizing a noble metal film coated with a catalyst on an inner wall of a hollow tube, and directly synthesizing hydrogen peroxide from hydrogen and oxygen. Further, the synthesized hydrogen peroxide is continuously recovered as a hydrogen peroxide water by an aqueous phase and a device thereof.

B-1‧‧‧ Hydrogen gas cylinder

B-2‧‧‧Air gas cylinder

B-3‧‧‧Oxygen gas cylinder

R-1~R-3‧‧‧pressure reducing valve

MFC-1~MFC-3‧‧‧Flow Controller

V-1~V-3‧‧‧ Shutoff Valve

CV-1~CV-5‧‧‧ check valve

P-1~P-3‧‧‧ pressure gauge

AT-1‧‧‧Recovery solution (acid solution) tank

SV-1~SV-2‧‧‧Safety valve

BV-1‧‧‧ ball valve

LP-1‧‧‧Quantitative liquid supply pump

T-1~T-2‧‧‧ thermometer

CL-1‧‧‧Recycling pipeline

M-1‧‧‧Mixer

BPR-1~BPR-2‧‧‧ back pressure valve

NV-1‧‧ needle valve

S-1‧‧‧ gas-liquid separator

MFM-1‧‧‧Flow Meter

G-1‧‧‧ gas bag

CR-1‧‧‧catalyst reaction tube

Claims (31)

The invention relates to a direct synthesis method of hydrogen peroxide, which is a method for directly synthesizing hydrogen peroxide from hydrogen and oxygen, which is characterized in that a reaction tube for coating a noble metal film on the inner wall of a hollow tube is used for hydrogen, oxygen or air of a raw material gas. The gas phase and the aqueous phase of the reaction medium are supplied to the flow path inside the reaction tube, and hydrogen peroxide is continuously and directly synthesized from hydrogen and oxygen in the reaction tube under a specific reaction temperature and reaction pressure. The synthesized hydrogen peroxide is continuously recovered as hydrogen peroxide water. The direct synthesis method of hydrogen peroxide according to claim 1, wherein an alloy of palladium, palladium and gold is used as the reaction tube, and the gold nanoparticles are deposited on the surface of the palladium film, and an alloy of palladium and silver is used. A reaction tube coated with any one of the porous membranes of palladium or the like. A direct synthesis method of hydrogen peroxide according to claim 1, wherein the noble metal film using the above reaction tube is a reaction tube coated by electroless plating. A direct synthesis method of hydrogen peroxide according to claim 1 or 3, wherein the film thickness of the noble metal film is in the range of 0.5 to 2 μm. The direct synthesis method of hydrogen peroxide according to any one of claims 1 to 4, wherein a stainless steel tube, an Inconel tube, a Hastelloy tube, or a titanium tube is used as the hollow tube system. Any one of the corrosion-resistant tubes selected from the corrosion-resistant tubes or the corrosion-resistant double tubes selected from the stainless steel tubes, the inconel tubes, and the Herstle alloy tubes. A direct synthesis method of hydrogen peroxide according to any one of claims 1 to 4, wherein fumed cerium oxide (fumed) is used as the hollow tube system Silica) tube. The direct synthesis method of hydrogen peroxide according to claim 5, wherein as the reaction tube, an alloy of palladium, palladium and gold is formed in the inside of the reaction tube by electroless plating, and the gold nanoparticles are deposited on the surface of the palladium film. When a film made of any one of the above, the alloy of palladium and silver, or the porous film of palladium is used, the metal is used as a base by high temperature oxidation at 600 ° C or higher or supercritical water oxidation at 374 ° C or higher. Oxidized film. The direct synthesis method of hydrogen peroxide according to any one of claims 1 to 7, wherein the inner diameter of the reaction tube is 10 mm or less and 0.05 mm or more, or 5 mm or less and 0.1 mm or more. The direct synthesis method of hydrogen peroxide according to any one of claims 1 to 8, wherein 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 0.1 to 20 MPa. range. The direct synthesis method of 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 by water or an aqueous acid solution. The direct synthesis method of hydrogen peroxide according to claim 10, wherein the water or acid aqueous solution recovered from the hydrogen peroxide synthesized inside the reaction tube contains any one of fluoride ion, chloride ion, bromide ion and iodide ion. The above ions. The method for directly synthesizing hydrogen peroxide according to claim 11, wherein the aqueous acid solution contains at least one of fluorine, chlorine, bromine and iodine, and the total concentration of any substance in the aqueous acid solution is 0.01 to 100 mg/L. range. The direct synthesis method of hydrogen peroxide according to claim 10 or 11, wherein the hydrogen peroxide synthesized in the inside of the reaction tube is continuously recovered, and the gas of the gas phase and the water phase of the raw material gas phase are mixed by a mixer, and the liquid phase is adjusted by The volumetric flow ratio is such that the phase of the raw material gas phase and the aqueous phase alternately form a slug flow, and the plugged hydrogen is used to synthesize the newly synthesized hydrogen peroxide into the reaction tube with hydrogen peroxide water. Continuous recycling. The direct synthesis method of hydrogen peroxide according to claim 13, wherein the volume ratio of the gas to the liquid is 5 to 50: liquid 1, and the volume flow ratio of the raw material gas phase to the recovered aqueous phase is set to be relative to the aqueous phase 1 gas. The phase is 50 or less, or a plug flow is formed with respect to the gas phase 1 gas phase of 10 or less. The direct synthesis method of hydrogen peroxide according to claim 13 or 14, wherein the inner diameter of the outflow portion of the mixer for mixing the gas of the raw material gas phase with the liquid of the aqueous phase is set to be the same as the inner diameter of the reaction tube and the inner diameter of the reaction tube joint. The diameter does not change the size of the plug flow due to the flow path. A direct synthesis method of hydrogen peroxide according to any one of claims 13 to 15, wherein a mass flow controller is used in the raw material gas phase and a metering pump is used in the aqueous phase to control the respective flow rate and discharge The pressure is mixed with the gas of the raw material gas phase and the liquid phase by a micro-mixer, thereby generating a plug flow. The direct synthesis method of hydrogen peroxide according to any one of claims 13 to 16, wherein the micromixer uses a T-type micro mixer to generate a stable plug flow. The direct synthesis method of hydrogen peroxide according to any one of claims 1 to 13, wherein a volume mixing ratio of hydrogen to oxygen is 10 to 33% of hydrogen, and oxygen is 90~. 67%, and the ratio of oxygen to hydrogen (oxygen/hydrogen) of the raw material gas phase is 1.6 or more, or the ratio of oxygen to hydrogen is 2.0 or more. A direct synthesis method of 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. A direct synthesizing device for hydrogen peroxide, which is a device for continuously synthesizing hydrogen peroxide by direct hydrogen and oxygen, characterized by comprising a reaction tube coated with a noble metal film on the inner wall of the hollow tube, and hydrogen and oxygen of the raw material gas or The means for supplying the gas phase of the air to the reaction tube, the means for supplying the aqueous phase of the reaction medium, and the means for continuously recovering the hydrogen peroxide which has been synthesized from the inside of the reaction tube by using water or an aqueous acid solution. A direct synthesis apparatus for hydrogen peroxide according to claim 20, wherein the reaction tube which coats the noble metal thin film on the inner wall of the tube by electroless plating includes an alloy of palladium, palladium and gold, an alloy of palladium and silver, and palladium. A reaction tube coated with any one of the porous membranes and coated with the film. A direct synthesis apparatus for hydrogen peroxide according to claim 20, wherein the noble metal film of the reaction tube is a reaction tube coated by electroless plating. A direct synthesis apparatus for hydrogen peroxide according to any one of claims 20 to 22, wherein a corrosion-resistant tube selected from the group consisting of a stainless steel tube, a inconel tube, a Hertzite tube, and a titanium tube is used as the hollow tube system. Or one of the corrosion-resistant double tubes selected from the stainless steel tube, the inconel tube, and the Herst alloy tube with the inner titanium liner. Direct combination of hydrogen peroxide as claimed in any one of claims 20 to 22. A device in which a fumed cerium oxide tube is used as the above hollow tube system. A direct synthesis apparatus for hydrogen peroxide according to claim 23, wherein as the reaction tube system, an alloy of palladium, palladium and gold is formed by electroless plating in the inside of the reaction tube, and the gold nanoparticles are deposited on the surface of the palladium film. When a thin film of any one or more of the above-mentioned alloy, the alloy of palladium and silver, or the porous film of palladium is used, the oxide film which is the metal of the base is oxidized at a high temperature of 600 ° C or higher or supercritical water of 374 ° C or higher. Produced by oxidation method. A direct synthesis apparatus for hydrogen peroxide according to any one of claims 20 to 25, wherein a flow path for entering the reaction tube is provided with a mixer which alternately forms a phase of the raw material gas phase and the aqueous phase to form a plug flow. The direct synthesizing apparatus for hydrogen peroxide according to any one of claims 20 to 24, wherein the inner diameter of the outflow portion of the mixer in which the raw material gas and the recovered water are mixed is the same diameter as the inner diameter of the reaction tube and the inner diameter of the reaction tube joint. . A direct synthesis apparatus for hydrogen peroxide according to any one of claims 20 to 27, which comprises means for continuously recovering hydrogen peroxide water by using hydrogen peroxide or an aqueous acid solution which is synthesized inside the reaction tube. A direct synthesis apparatus for hydrogen peroxide according to any one of claims 20 to 28, comprising: a mass flow controller for controlling supply of a raw material gas phase; and a quantitative pump for controlling supply of the aqueous phase, and the mass flow controller and Downstream of the above-mentioned dosing pump, a micro-mixer that mixes the raw material gas phase and the water phase is disposed so that the phase state of the raw material gas phase and the water phase alternates continuously to generate a plug flow. A direct synthesis apparatus for hydrogen peroxide according to any one of claims 26 to 29, wherein said micromixer uses a T-type micro mixer, Produces a stable plug flow. A direct synthesis apparatus for hydrogen peroxide according to any one of claims 20 to 29, which is provided with a recycling means for recycling the recovered aqueous phase flowing out of the reaction tube to the reaction tube.