JPH10330103A - Production of aqueous hydrogen peroxide solution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the decomposition of hydrogen peroxide and obtain an aqueous hydrogen peroxide solution having a high concentration by reacting hydrogen with oxygen in a reaction solvent containing the carboxylic acid salt of a platinum group metal. SOLUTION: This method for producing an aqueous hydrogen peroxide solution comprises charging 1 mg to 10 g, preferably 1 mg to 1 g, of a particulate platinum group metal 1-5C carboxylic acid salt selected from palladium acetate, palladium oxalate, palladium trifluoroacetate, rhodium acetate, rhodium trifluoroacetate, etc., and having a specific surface area of 0.01-10000 m<2> /g, and 100 ml of a reaction solvent comprising water and/or a 1-4C alcohol into a reaction vessel, charging oxygen and hydrogen in a partial pressure ratio of 1:50 to 50:1 into the reaction vessel and subsequently reacting the oxygen with hydrogen at a pressure of the atmospheric pressure to 150 kg/cm<2> .G, preferably 5-50 kg/cm<2> .g, at 5-60 deg.C, preferably 10-50 deg.C. The method does not require a process for removing an additive such as an acid, a halide ion or formaldehyde.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing hydrogen peroxide. More specifically, the present invention relates to a method for producing hydrogen peroxide by directly reacting hydrogen and oxygen.

[0002]

2. Description of the Related Art Hydrogen peroxide is used as a bleaching agent (paper / pulp, natural fiber), industrial chemicals (oxidizing and plasticizing agents, rubber chemicals,
It is one of the most important industrial products with a wide variety of applications, such as reducing agents for pollution treatment, pharmaceuticals (oxidizing agents), and foods (bleaching and disinfecting agents for fishery processing, and various other bleaching agents).

At present, the most common industrial production method of hydrogen peroxide is based on an autoxidation method using alkylanthraquinone. However, a problem of this method is that many steps such as reduction and oxidation of alkylanthraquinone and extraction separation, purification, and concentration of generated hydrogen peroxide are required, and the process becomes complicated. There are also problems such as loss of alkylanthraquinone and deterioration of the reduction catalyst.

[0004] In order to solve these problems, conventionally, hydrogen and oxygen are contacted in an aqueous medium in the presence of a platinum group metal,
Methods for directly synthesizing hydrogen peroxide have been proposed (JP-B-55-18646, JP-B-56-47121, JP-B-1-23401, JP-A-63-15).
No. 6005). In each of these, a solution to which an acid or a compound which dissociates to generate halide ions is added as a reaction medium is used.

For example, Japanese Patent Application Laid-Open No. 63-156005 discloses that in the presence of a platinum group metal supported on a support, an aqueous medium containing an acid and a halide ion is subjected to a somewhat higher concentration of hydrogen and oxygen under high pressure conditions. It can produce hydrogen peroxide. However, in this method, it is necessary to add an acid in a high concentration and to coexist with a compound which dissociates to generate a halide ion, for example, sodium bromide. Therefore, a step of adding these and a step of removing them are required, which is industrially disadvantageous.

JP-A-57-92506 describes that alcohol, ketone, ether, ester, amide and the like can be used as a reaction medium, and methanol is particularly excellent. However, also in this method, the platinum group metal, acid and halide ions supported on the support are used, and further, formaldehyde must be coexisted in methanol in order to suppress the decomposition of the generated hydrogen peroxide. . Therefore,
A step of adding an acid, a halide ion, and formaldehyde and a step of removing the acid are required, which is complicated and industrially disadvantageous.

[0007]

The problem to be solved by the present invention, that is, an object of the present invention is to produce an acid or halide ion and formaldehyde when hydrogen and oxygen are directly reacted to produce hydrogen peroxide. Without adding any of the additives such as, the decomposition of the generated hydrogen peroxide is also suppressed,
An object is to provide a method for producing a high concentration of hydrogen peroxide.

[0008]

Means for Solving the Problems In view of the above-mentioned circumstances, the present inventors have intensively studied a method for producing hydrogen peroxide by directly reacting hydrogen and oxygen in a reaction medium, and have completed the present invention. Reached. That is, the present invention relates to a method for producing hydrogen peroxide, in which hydrogen and oxygen are reacted in a reaction medium containing a carboxylate of a platinum group metal.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. In the carboxylate of the platinum group metal used in the present invention, examples of the platinum group metal include rhodium and palladium, but palladium is preferably used. As examples of the carboxylate, a salt of a carboxylic acid having 1 to 5 carbon atoms is preferable, and specific examples thereof include an oxalate, an acetate, and a trifluoroacetate. Preferably, it is an acetate. Specific examples of the platinum group metal carboxylate include palladium acetate, palladium oxalate, palladium trifluoroacetate, rhodium acetate, rhodium trifluoroacetate and the like, preferably, palladium acetate, palladium oxalate, trifluoroacetate Palladium acetate, more preferably palladium acetate.

The amount of the carboxylate of the platinum group metal is not particularly limited, but usually, in the case of a suspension bed system, the reaction medium 1
1 mg or more and 10 g or less, preferably 1
It is carried out in the range of 0 mg to 1 g. The form of the carboxylate of the platinum group metal may be any form such as a fine powder, a pellet, or the like, but is preferably a fine powder and has a surface area of 0.0
Those having a mass of ^{1 to} 10,000 m ² / g are preferably used.

In the present invention, the carboxylate of a platinum group metal can be used alone or can be used by being supported on a suitable carrier. In general, the more supported, the greater the activity per metal weight. As the carrier, for example, alumina, silica, titania, magnesia, zirconia, ceria, zeolite, graphite, activated carbon, silica gel,
Hydrated silicic acid, silicon carbide, fluorinated graphite, etc .; alumina, silica, titania, zeolite, graphite,
Activated carbon and fluorinated graphite are preferably used.

The method of supporting the carrier is not particularly limited as long as the carrier can be supported, such as a method in which the carrier is suspended in a solution of a carboxylate of a platinum group metal and evaporated to dryness.

In the present invention, a reaction medium is used.
For example, water or an organic compound which is liquid in the reaction system, a mixture thereof, or the like is used. Such organic compounds include, for example, alcohols, ketones, ethers, esters, amides and the like. The reaction medium used in the present invention is preferably water and / or alcohol. More preferably, it is an alcohol alone or a mixed liquid of alcohol and water. In the case of the mixed liquid, it is preferable that the volume contains 80% or more of alcohol, more preferably 90% or more of alcohol.

Specific examples of the alcohol include alcohols having 1 to 8 carbon atoms, preferably 1 to 4 carbon atoms, such as methanol, ethanol, and isopropyl alcohol, and glycols such as ethylene glycol. Or a mixture of them. Preferred are methanol and ethanol, and more preferred is methanol.

In the present invention, a high-concentration hydrogen peroxide solution can be obtained without adding an acid. However, when the coexistence of the acid in the hydrogen peroxide solution after the reaction does not pose a problem, sulfuric acid and hydrochloric acid are used. And acids such as phosphoric acid.

The reaction of the present invention can be either a continuous system or a batch system, and the reaction apparatus can be a suspension bed system, a fixed bed system, or the like. These are not particularly limited.

The partial pressure ratio between oxygen and hydrogen can be generally set in the range of 1:50 to 50: 1. The reaction can be carried out by diluting with an inert gas, or the reaction can be carried out using air instead of oxygen. However, it is preferable to carry out the reaction outside the explosion range for safety. Reaction temperature is 5 ° C to 60
C., preferably in the range of 10.degree. C. to 50.degree. The reaction pressure is not particularly limited, but is preferably atmospheric pressure to 150 kg / cm ² · G, particularly 5 to 50 kg / cm ^2.
-Implemented in the range of G.

[0018]

The present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples.

The concentration of hydrogen peroxide in the examples was determined by adding potassium iodide (manufactured by Wako Pure Chemical Industries, Ltd.) in excess under sulfuric acid (0.2 N) conditions, and liberating iodine by 0.1 mol for volumetric analysis. / 1 sodium thiosulfate solution (manufactured by Wako Pure Chemical Industries, Ltd.) at room temperature by a titration method. For the titration, an automatic potentiometer AT-310 manufactured by Kyoto Electronics Industry Co., Ltd. was used.

Example 1 30 mg of palladium acetate (manufactured by Wako Pure Chemical Industries, Ltd.)
Then, a glass inner cylinder having an inner volume of 300 ml charged with 120 ml of methanol as a reaction medium was mounted in an autoclave having an inner volume of 400 ml. 80 ml / min of hydrogen gas and 800 ml / mi of oxygen gas by gas injection pipe
n. For safety, put 2 nitrogen gas in the gas phase
It was introduced and diluted at 500 ml / min. The pressure is maintained so that the internal pressure of the autoclave becomes 9 kg / cm ² · G,
The reaction was kept at 20 ° C. by external cooling. The concentration of hydrogen peroxide in the reaction solution after 2 hours from the start of the reaction is 0.08 wt%
Met. The amount of hydrogen peroxide generated per 1 mg of palladium acetate was 0.06 mmol.

Comparative Example 1 30 mg of palladium acetate was added to Pd / C (produced by NE Chemcat Corporation: Pd content: 5%: specific surface area: 800 m)
² / g) The reaction was carried out under the same conditions as in Example 1 except that the amount was 30 mg. Two hours after the start of the reaction, the concentration of hydrogen peroxide in the reaction solution was below the detection limit (0.00 wt%).

[0022]

According to the process for producing hydrogen peroxide of the present invention, the reaction proceeds by using a compound having a small number of preparation steps without the need for a step of adding or removing an acid or a halide ion. Also produces a large amount of hydrogen peroxide. As a result, the production of hydrogen peroxide in a much simplified process is possible.

Claims (4)

[Claims] 1. A method for producing hydrogen peroxide, comprising reacting hydrogen and oxygen in a reaction medium containing a carboxylate of a platinum group metal. 2. The method for producing hydrogen peroxide according to claim 1, wherein the reaction medium is water and / or alcohol. 3. The method for producing hydrogen peroxide according to claim 1, wherein the platinum group metal is palladium. 4. The method for producing hydrogen peroxide according to claim 1, wherein the carboxylate is an acetate.