JPS5910921B2 - Hydrogen production method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing hydrogen, and more particularly to a method for producing hydrogen using carbon monoxide or hydrocarbons.

Hydrogen is one of the important raw materials for the chemical industry, and there is a large demand for it, and in recent years, with the development of processes that consume large amounts of hydrogen, such as hydrodesulfurization of heavy oil, liquefaction of coal, and gasification of coal, The demand for cheap, high-purity hydrogen is increasing significantly.

Hydrogen synthesis is divided into methods using water as a raw material and methods using hydrocarbons as a raw material, but in recent years the latter has become the mainstream.

In this method, a mixture of hydrocarbons resulting from, for example, petroleum cranking and steam are heated in the presence of a nickel catalyst, etc.
The reaction is carried out under conditions of around 00°C.

In this method, the reaction proceeds as shown in the formula (II), and hydrogen is generated from the by-produced carbon monoxide by the reaction of the formula (I) at around 400°C.

However, this process requires high-temperature reaction conditions of 800°C, which requires high-grade materials such as heat-resistant steel for the equipment material, and to purify hydrogen, Separation operations for unreacted components, water vapor, carbon dioxide, etc. are required, making the process complicated.

Furthermore, a large amount of hydrogen is produced as a by-product in the aromatic hydrocarbon production reaction illustrated in the following formula (3), but hydrogen is merely a by-product and is not intended only to increase the amount of hydrogen.

On the other hand, methods using water as a raw material include electrolysis and steam-iron reactions, but these require a large amount of energy and are rarely used today. do not have.

Under these circumstances, it has been desired to develop a highly efficient and simple method for producing hydrogen using less energy.

An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to provide a method for producing high-purity hydrogen from CO or hydrocarbons and steam at relatively low temperatures.

The present inventors investigated a method of synthesizing hydrogen by reaction with reducing gas and water vapor using various metal oxides as catalysts in the temperature range of 300°C to 500°C, and found that molybdenum (Mo), Tungsten (4), uranium (U) with vanadium, iron (Fe), Futsuku/KN
It was discovered that a catalyst prepared by adding a platinum group element such as rhodium (Rh) to a transition metal oxide such as i) exhibits high activity, and as a result of intensive research, the present invention was arrived at.

That is, the present invention provides Mo, W, V, U, Fe and N
A substance in which a platinum group element represented by rhodium (Rh) is added to one or more oxides selected from the transition metal oxide group consisting of i, etc. (hereinafter referred to as a catalyst as it has a strong catalytic effect)
is reacted with CO or a hydrocarbon, which is then contacted with water vapor to obtain hydrogen.

As mentioned above, for example, a transition metal oxide doped with rhodium is easily reduced by a hydrocarbon such as CO or hexane at a temperature of 300°C or higher due to the action of rhodium, and then it is brought into contact with water vapor. It quickly reacts with hydrogen to generate hydrogen, which is then oxidized.

In the present invention, examples of transition metal oxides to which platinum group elements are added include oxidized moieties of Mo, W, V, U, Fe, and Ni; It can be a thing.

Rhodium (Rh) is the most versatile platinum group element to be added to the transition metal oxide, but high activity can also be obtained with other platinum group elements such as platinum and palladium.

The amount of platinum group element added to the above oxide is typically 0.
．． 05 to 5% by weight.

Any metal oxide raw material can be used for producing the above catalyst, and any platinum group element raw material such as nitrate, chloride, carbonyl, organic acid salt, etc. can be used.

The above catalyst can be obtained by mixing the above metal oxide and platinum group element, for example, in an aqueous nitric acid solution, evaporating to dryness, calcining, molding the obtained powder, and further pulverizing it to a predetermined particle size. It will be done.

Next, the method of the present invention will be explained in more detail with reference to the drawings.

FIG. 1 is a block diagram of the process underlying the invention.

In the figure, a reducing gas (raw material gas) containing CO or hydrocarbons led from a line 1 is brought into contact with a catalyst in a reduction reactor 10 and is discharged from a line 11 after reducing the catalyst.

The reduced catalyst is led from line 12 to hydrogen generation reactor 20 .

When water vapor is supplied from line 2 and brought into contact with the catalyst in the reduced state, hydrogen is generated. Hydrogen gas containing unreacted water vapor is led to water separator 30 through line 21, and the hydrogen gas from which water has been removed is It is taken out from line 31.

The separated water is discharged through line 32.

After the hydrogen generation reaction is completed, the catalyst in an oxidized state is returned to the reduction reactor 10 through the line 22 and is again subjected to a reaction with the reducing gas.

In the present invention, a reducing gas such as CO or hydrocarbon is used as the raw material gas, but oxygen (0
2) or water vapor (H20), the reaction yield decreases.

Therefore, if the processing gas contains these interfering components,
It is preferable to remove them in the pretreatment step.

FIG. 2 shows an example of such a process.

In FIG. 2, CO or hydrocarbon feed gas containing 02 and H20 is passed through line 1 to deoxygenation reactor 4.
It leads to 0.

As the oxygen absorber, an oxygen absorber such as an aqueous pyrogallol solution can be used.

The deoxygenated raw gas is led to the moisture removal device 50 through the line 41, and the moisture can be removed by a method such as cooling and condensation.

The raw material gas from which moisture has been removed is led to the reduction reactor 10 through the line 51, and the subsequent process is the same as that described in FIG.

In the present invention, since a highly active catalyst is used as described above, the reaction temperature of the process is 300°C or higher, usually 30°C.
The temperature may be 0 to 500°C.

Hereinafter, the present invention will be specifically explained with reference to Examples.

Example 1 Catalysts AK shown in Table 1 were prepared as follows.

That is, 50? of the oxides shown on each catalyst? platinum group element 1
It is mixed with a nitric acid aqueous solution 5007d containing 1/t, and water and acid are evaporated to dryness.

Subsequently, it was calcined in air at 500°C for 2 hours, and the obtained powder was molded using a hydraulic press into a size of 10 mrn in diameter and 5 mm in length, and then ground into a size of 10 to 20 mesh, and then heated in a hydrogen stream. Reduction treatment was performed at 450°C for 1 hour.

Using 501 of each of these catalysts, they were brought into contact with 20 mmol of CO at 400°C for 1 second, and carbon dioxide gas (CO2
) was measured.

Next, the catalyst was brought into contact with water vapor of 100 mmα for 1 second, and the amount of hydrogen (H2) generated was measured.

These fruits. The test results are also shown in Table 1.

? Example 2 A simulated gas consisting of 10% H2O, 10% H20, and residual CO was synthesized, and this gas and catalyst A were brought into contact in the same manner as in Example 1.

As a result, H2 was not generated.

Example 3 A system was provided in which an oxygen trap containing an aqueous pyrogallol solution in a glass container equipped with a bubbler and a steam trap having a U-shaped tube immersed in ice water were arranged, and 1 t/h of the synthesis gas of Example 2 was set up. After treatment at a rate of min., it was brought into contact with catalyst A- in the same manner as in Example 2.

As a result, I6.2mmobDH2 could be generated.

Example 4 The reaction temperature of Example 1 was changed from 400°C to 300°C and 500°C.
The same test as in Example 1 was conducted using Catalyst A.

The results are shown in Table 2. Example 5 A similar test was conducted on Catalyst A in Example 1, using propane instead of CO.

As a result, 2 3 m mot of H2 could be generated.

As a result, it was found that the present invention can also be applied to hydrocarbons typified by propane.

As described above, according to the present invention, hydrogen can be efficiently produced from CO or hydrocarbon and water vapor by a simple method in the low temperature range of 300 to 500°C.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the basic process flow for implementing the present invention, and FIG. 2 is a block diagram showing the flow of the process of the present invention including pretreatment of treatment gas, that is, oxygen removal and moisture removal steps. be. 1-...1...Reducing gas introduction line, 2-...Steam introduction line, 10-...1...Reduction reactor, 20-...
...Hydrogen generation reactor, 30-...Water separator, 31-...Hydrogen extraction line.

Claims (1)

[Claims] 1. A reducing gas containing carbon monoxide or a hydrocarbon is converted into an oxide of at least one transition metal selected from the group consisting of molybdenum, tungsten, vanadium, uranium, iron, and nickel. A method for producing hydrogen comprising the steps of contacting the material with a substance to which a platinum group element has been added, and contacting the material after the reducing gas contact treatment with water vapor to generate hydrogen gas. 2. A method for producing hydrogen according to claim 1, which includes a pretreatment step for reducing and removing reaction-interfering components such as oxygen and water vapor contained in the raw material gas. 3. The method for producing hydrogen according to claim 1 or 2, characterized in that the step is carried out at a temperature of 300°C to 500°C.