JPH1067506A - Production of purified hydrogen peroxide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a high concentration solution of purified hydrogen peroxide (H2 O2 ) without adding HCHO and preventing the H2 O2 from degrading by reacting H2 with O2 in the presence of a platinum group metal and using an alcoholic medium containing an acid and a specific compound as a reaction medium. SOLUTION: H2 and O2 in e.g. (50:1) to (1:50) partial pressure ratio are reacted by using an alcoholic medium (an aqueous methanol) containing an acid, preferably H2 SO4 having preferably 0.001-1N concentration and a halogenated alkali(ne earth) metal (e.g. NaBr), preferably a chloride or bromide of an alkali metal and having preferably 1×10<-6> to 1×10<-3> N concentration as a reaction medium in the presence of a platinum group metal (e.g. Pd) at preferably 5-60 deg.C reaction temperature. The reaction proceeds even under a low pressure condition, which is extremely preferable in respect of safety.

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 in an alcoholic medium.

[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).

For example, Japanese Patent Application Laid-Open No. 63-156005 discloses that a somewhat high concentration of hydrogen peroxide can be produced from oxygen and hydrogen in an aqueous medium in the presence of a platinum group metal supported on a support. In order to obtain hydrogen peroxide, it was necessary to carry out the reaction under high pressure conditions. The production of hydrogen peroxide under high pressure conditions is costly for constructing various facilities and is industrially disadvantageous. In consideration of reacting an explosive combination of hydrogen and oxygen, high-pressure conditions are not preferable in terms of safety. It is important to establish a method for producing high concentration hydrogen peroxide even under low pressure conditions.

[0006] JP-A-57-92506 discloses that alcohols, ketones, and the like are used as reaction media under relatively mild conditions.
Although ethers, esters, amides and the like can be used, it is described that methanol is particularly excellent.
However, in order to obtain a hydrogen peroxide solution to some extent efficiently, it was necessary to coexist formaldehyde in the reaction medium in order to suppress the decomposition of the generated hydrogen peroxide. Therefore, there is a problem that a step for adding this and a purification step for removing it are required, and the process becomes complicated.

[0007]

The problem to be solved by the present invention, that is, an object of the present invention is to produce hydrogen peroxide by directly reacting hydrogen and oxygen without the addition of formaldehyde. It is an object of the present invention to provide a method for producing mild and high-concentration hydrogen peroxide in which decomposition of hydrogen peroxide is suppressed.

[0008]

Means for Solving the Problems In view of the above-mentioned circumstances, the present inventors have continued intensive studies on a method for producing hydrogen peroxide by directly reacting hydrogen and oxygen in an alcoholic medium.
The present invention has been completed. That is, the present invention relates to a method for producing hydrogen peroxide in which an alcoholic medium containing a halide of an alkali metal or an alkaline earth metal is used as a reaction medium, and hydrogen and oxygen are reacted in the presence of a platinum group metal. Such is the case. Hereinafter, the present invention will be described in detail.

[0009]

DETAILED DESCRIPTION OF THE INVENTION The reaction medium used in the present invention is an alcoholic medium. The alcoholic medium in the present invention refers to alcohol or a mixed solution containing alcohol as a main component, and a single alcohol medium is usually used. As the alcohol, methanol, ethanol, isopropanol, butanol, ethylene glycol and the like are used, but methanol and ethanol are preferred, and methanol is more preferred.

The reaction medium used in the present invention contains an alkali metal or alkaline earth metal halide. Specific examples include, but are not limited to, sodium fluoride, sodium chloride, sodium bromide, sodium iodide, magnesium chloride, potassium bromide, calcium chloride, and the like. Preferably, an alkali metal chloride, bromide or iodide is used, more preferably an alkali metal chloride or bromide, and particularly preferably an alkali metal bromide. The amount of the alkali metal or alkaline earth metal halide used is usually 1 × 10 ⁻⁶ to 1 × 10 ^6
-3N , preferably 1 × 10 ^-5 to 1 × 10 ^-3 N.

The reaction medium used in the present invention contains an acid. As the acid, sulfuric acid, hydrochloric acid, phosphoric acid and the like can be used. It is also possible to use a mixture of these acids. Sulfuric acid is preferably used as acid. The acid concentration is usually carried out at 0.001 to 1N, preferably 0.01 to 1N.

Specific examples of the platinum group metal used in the present invention include rhodium, iridium, platinum and palladium, preferably palladium. The platinum group metal may be used alone or may be used by being supported on various carriers such as activated carbon. Various types of such supported platinum group metals are commercially available, and can be appropriately selected and used therefrom.

[0013] The form of the platinum group metal used in the present invention may be any form such as a fine powder or pellets, and the reaction may be either a continuous type or a batch type. Can be used. These are not particularly limited.

The amount of the platinum group metal to be used is not particularly limited. In the case of a suspension bed system, the amount is usually from 1 mg to 100 g, preferably from 10 mg to 10 g, per 100 ml of the reaction medium.

The partial pressure ratio between oxygen and hydrogen is 1:50 to 50:50.
It can be performed in the range of one to one. 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. The reaction is generally carried out at a temperature in the range from 5C to 60C, preferably from 10C to 50C. The reaction pressure is not particularly limited, but may be from atmospheric pressure to 150 kg /
cm ² · G, particularly in the range of 5 to 50 kg / cm ² · G.

[0016]

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.

In the examples, the concentration of hydrogen peroxide was determined by adding an excess of potassium iodide (manufactured by Wako Pure Chemical Industries, Ltd.) under sulfuric acid (0.2 N) conditions, and releasing the released iodine by 0.1 mol for volumetric analysis. / Liter-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 Pd powder as a catalyst (Tanaka Kikinzoku International
Made: Specific surface area 10.8m ^Two/ G) 30 mg, with the reaction medium
And 5 ml of a methanol solution of 0.0012N-NaBr.
1.2N-H_TwoSO_Four5 ml of methanol solution and methanol
Volume 3 containing 110 ml of the mixed methanol solution
00ml glass inner cylinder, 400ml auto volume
Attached to the clave. Hydrogen gas with gas injection pipe
80 ml / min, oxygen gas at 800 ml / min
Inflowed. For safety, 2,500 nitrogen gas in gas phase
It was introduced and diluted at ml / min. Autoclave internal pressure
9kg / cm^Two・ Keep the pressure to G
Was kept at 20 ° C. by external cooling. 2 hours after the start of the reaction
The hydrogen peroxide concentration in the reaction solution was 0.84 wt%.
Was. The amount of hydrogen peroxide generated per mg of Pd is 0.6
6 mmol.

Comparative Example 1 6 ml of a 0.001 N aqueous NaBr solution and 1 N
Except that the -H ₂ SO ₄ aqueous solution 6ml and mixed aqueous solution of ion-exchanged water 108 ml, the reaction was carried out under the same conditions as in Example 1. Two hours after the start of the reaction, the concentration of hydrogen peroxide in the reaction solution was 0.10 wt%. In addition, Pd1mg
The amount of hydrogen peroxide produced per unit was 0.08 mmol.

Example 2 The reaction medium was a 0.0012N NaCl methanol solution 5
except ml and 1.2N-H ₂ SO ₄ that was mixed methanol solution in methanol 5ml and methanol 110 ml, the reaction was carried out under the same conditions as in Example 1. After 2 hours from the start of the reaction, the concentration of hydrogen peroxide in the reaction solution was 1.00 W
t%. The amount of hydrogen peroxide generated per 1 mg of Pd was 0.78 mmol.

Example 3 The reaction medium was 5 m of a 0.0012 N NaI methanol solution.
except that it was a mixed methanolic solution of l and 1.2N-H ₂ SO ₄ in methanol 5ml and methanol 110 ml, the reaction was carried out under the same conditions as in Example 1. The concentration of hydrogen peroxide in the reaction solution after 2 hours from the start of the reaction is 0.22 wt.
%Met. The amount of hydrogen peroxide generated per 1 mg of Pd was 0.17 mmol.

COMPARATIVE EXAMPLE 2 The reaction medium was 5 ml of a 1.2N—H ₂ SO ₄ methanol solution.
The reaction was carried out under the same conditions as in Example 1 except that a mixed methanol solution of 115 ml of methanol was used. Two hours after the start of the reaction, the concentration of hydrogen peroxide in the reaction solution was 0.0
It was 1 wt%. The amount of hydrogen peroxide generated per 1 mg of Pd was 0.01 mmol.

Comparative Example 3 Example 1 was repeated except that the reaction medium was a mixed methanol solution of 5 ml of a 0.03 N-HCl methanol solution, 1.3 ml of a 1.2 N-H ₂ SO ₄ methanol solution and 113.7 ml of methanol. The reaction was carried out under the same conditions as described above. Two hours after the start of the reaction, the concentration of hydrogen peroxide in the reaction solution was 0.18.
wt%. The amount of hydrogen peroxide produced per mg of Pd was 0.14 mmol.

Comparative Example 4 A reaction was carried out under the same conditions as in Comparative Example 3 except that 0.25 g of a 37% aqueous formaldehyde solution was added to the reaction medium of Comparative Example 3. Two hours after the start of the reaction, the concentration of hydrogen peroxide in the reaction solution was 0.31% by weight. Note that Pd1
The amount of hydrogen peroxide generated per mg was 0.25 mmol.

[0025]

According to the method of the present invention for producing hydrogen peroxide using an alcoholic medium, a hydrogen peroxide solution having a higher concentration than that of an aqueous medium can be obtained. Very preferred for safety. In addition, since the reaction can be carried out without adding an aldehyde, hydrogen peroxide can be produced by a simplified process.

Claims (5)

[Claims] 1. A peroxide, characterized by reacting hydrogen and oxygen in the presence of a platinum group metal, using an alcoholic medium containing an acid and an alkali metal or alkaline earth metal halide as a reaction medium. Hydrogen production method. 2. The method for producing hydrogen peroxide according to claim 1, wherein the alcohol is methanol or ethanol. 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 alkali metal or alkaline earth metal halide is an alkali metal chloride or bromide. 5. The method for producing hydrogen peroxide according to claim 1, wherein the acid is sulfuric acid.