JP2000103604A - Preparation of reforming catalyst for hydrocarbon and molded product of magnesium oxide for forming the same catalyst support - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for preparing a catalyst for reforming a hydrocarbon having a small amount of a supported noble metal and producing a small amount of a deposited carbon in use. SOLUTION: This method for preparing a catalyst for reforming a hydrocarbon comprises (i) a first step for providing a support magnesium oxide having <=5 m2/g specific surface area, (ii) a second step for supporting rhodium and/or ruthenium in an amount of 10-5,000 (wt.ppm) based on the support magnesium oxide expressed in terms of the metals on the support magnesium oxide within an alkaline region of pH >=8 using an aqueous solution of a water-soluble rhodium compound and/or a water-soluble ruthenium compound for the support magnesium oxide prepared in the first step according to an equilibrium adsorption method, (iii) a third step for drying the rhodium- and/or ruthenium-supported magnesium oxide obtained in the second step at <=35 deg.C for at least >=6 h and (iv) a fourth step for baking the rhodium- and/or ruthenium-supported magnesium oxide in the dry state obtained in the third step at a high temperature of >=200 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preparing a catalyst for reforming hydrocarbons and a magnesium oxide molded body for forming a catalyst carrier.

[0002]

2. Description of the Related Art A synthesis gas obtained by reforming a hydrocarbon is a mixed gas comprising hydrogen and carbon monoxide.
It is widely used as a raw material for the synthesis of industrial products such as ammonia, methanol, and acetic acid. In general, synthesis gas can be produced by reacting a hydrocarbon with steam and / or carbon dioxide gas in the presence of a catalyst (Japanese Patent Laid-Open No. Hei 5 (1993) -107).
-208801, JP-A-6-279003, JP-A-9-168740, etc.). However, in this reaction, as a side reaction, there is a problem that a carbon deposition reaction occurs to deposit carbon, and the deposited carbon causes catalyst poisoning. In this reforming reaction, it is well known that when a noble metal is used as a catalyst metal, carbon precipitation is easily suppressed as compared with a transition metal such as Ni, but in this case, the noble metal is very expensive, so It has been desired to establish a method for preparing a catalyst that can effectively utilize a small amount of metal for the reaction.

[0003]

SUMMARY OF THE INVENTION The present invention provides a method for preparing a catalyst for reforming hydrocarbons having a small amount of noble metal carried and a small amount of carbon deposited during use, and a magnesium oxide molded body for forming the catalyst carrier. Is the task.

[0004]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have completed the present invention. That is, according to the present invention, (i) the specific surface area is 5
Rhodium and / or ruthenium are added to a carrier magnesium oxide of m ² / g or less in a metal conversion amount of 10 to 5000 wtp.
The present invention provides a method for preparing a hydrocarbon reforming catalyst, wherein the catalyst is supported at a ratio of pm and then calcined. Further, according to the present invention, (i) the first step of obtaining a carrier magnesium oxide having a specific surface area of 5 m ² / g or less, (ii) the first step
An aqueous solution containing a water-soluble rhodium compound and / or ruthenium compound is used as the carrier magnesium oxide obtained in the step, and rhodium and / or ruthenium are converted to a metal equivalent of 10 to 10 in an alkaline region of pH 8 or more by an equilibrium adsorption method. 5
A second step of loading at a rate of 2,000 wtppm, (ii)
i) a third step of drying the rhodium and / or ruthenium-supported magnesium oxide obtained in the second step, (iv)
A method for preparing a hydrocarbon reforming catalyst is provided, which comprises a fourth step of calcining the magnesium oxide supporting rhodium and / or ruthenium in a dry state obtained in the third step. Further, according to the present invention, (i) a first method for obtaining a carrier magnesium oxide having a specific surface area of 5 m ² / g or less.
And (ii) using an aqueous solution containing a water-soluble rhodium compound and / or ruthenium compound as the carrier magnesium oxide obtained in the first step, and performing rhodium and / or rhodium in an alkaline region having a pH of 8 or more by an equilibrium adsorption method. A second step in which ruthenium is supported at a rate of 10 to 5000 wtppm in terms of metal, (iii) rhodium and / or ruthenium-supported magnesium oxide obtained in the second step is converted to 35
A third step of drying at least 6 hours at or below
(Iv) the dried rhodium and / or obtained in the third step;
Alternatively, there is provided a method for preparing a hydrocarbon reforming catalyst, comprising a fourth step of calcining ruthenium-supported magnesium oxide. Furthermore, according to the present invention,
(I) a first step of obtaining a carrier magnesium oxide having a specific surface area of 5 m ² / g or less; (ii) the carrier magnesium oxide obtained in the first step contains a water-soluble rhodium compound and / or a ruthenium compound. A second step of supporting rhodium and / or ruthenium at a ratio of 10 to 5000 wtppm in terms of metal in an alkaline region having a pH of 8 or more by an equilibrium adsorption method using an aqueous solution, (iii) rhodium obtained in the second step; And / or drying ruthenium-supported magnesium oxide at 35 ° C. or lower for at least 6 hours or more.
(Iv) drying the rhodium and / or ruthenium-supported magnesium oxide obtained in the third step,
A method for preparing a hydrocarbon reforming catalyst is provided, which comprises a fourth step of firing at a high temperature of not less than ° C. Furthermore, according to the present invention, it comprises a mixture of magnesium oxide and a forming aid, wherein the forming aid comprises (i) carbon, (i)
i) at least one selected from fatty acids having 12 to 22 carbon atoms or magnesium salts thereof, (iii) carboxymethylcellulose or magnesium salts thereof, and (iv) polyvinyl alcohol, and the amount of addition is 0.1
To 5% by weight of the magnesium oxide shaped body for forming a catalyst carrier used in the above method.

[0005]

DETAILED DESCRIPTION OF THE INVENTION In the present invention, magnesium oxide (hereinafter, also simply referred to as MgO) is used as a catalyst carrier. As this MgO, a commercial product can be used,
The shape is not particularly limited, and may be various shapes used as a catalyst, for example, a powdery shape, a granular shape, a spherical shape, a columnar shape, a cylindrical shape, and the like. As MgO, magnesium hydroxide is used at 1000 to 1500 ° C., preferably at 11 ° C.
What was obtained by calcining at 00 to 1300 ° C, magnesium carbonate or basic magnesium carbonate was 1000 to 15
It is possible to use those obtained by firing at 00 ° C, preferably at 1100 to 1300 ° C.

According to the present invention, a catalyst for hydrocarbon reforming (hereinafter referred to as "catalyst")
A preferred method for preparing the catalyst (hereinafter simply referred to as catalyst) is as follows. First, in the first step, a support MgO having a specific surface area of 5 m ² / g or less is obtained. In an industrial catalyst, a carrier formed into a shape such as a pellet or a ring is preferably used.
When using a molded body, when the specific surface area of the MgO is larger than the above range and the crystallinity is low, when the MgO molded body is immersed in an aqueous solution when supporting a catalyst metal,
There is a problem that cracks occur in the MgO compact. In the case of an industrial catalyst, it is usually necessary to have a compressive strength in the radial direction of 30 to 40 kg / piece. However, such a strength is required for an MgO molded body having a specific surface area larger than the above range and a low crystallinity. Will be difficult to obtain. further,
When the crystallinity of the support MgO is low, the amount of the supported catalyst metal increases, and the acid strength of the catalyst becomes too strong, so that the acid properties of the catalyst surface become unsatisfactory. On the other hand, the carrier M
If the crystallinity of gO is too large, the amount of the supported catalyst metal is too small, and a catalyst having a sufficient activity cannot be obtained. From this point, the specific surface area of the support MgO is 0.1.
It is preferably at least 01 m ² / g.

One method for obtaining a carrier MgO having a specific surface area in the above range is as follows.
0 to 1500 ° C., preferably 1100 to 1300 ° C., and magnesium carbonate or basic magnesium carbonate of 1000 to 150 ° C.
It can be manufactured by baking at 0 ° C, preferably 1100 to 1300 ° C. Also, when firing at a low temperature of 1000 ° C. or less, the desired carrier MgO can be obtained by increasing the partial pressure of water produced as a by-product during firing to promote crystallization of MgO and controlling the crystallite size of MgO. Can be obtained. Further, those having a specific surface area smaller than the above range, such as commercially available MgO, have the MgO of 1000 to 1
By firing at 500 ° C., preferably 1100 to 1300 ° C., a desired carrier MgO can be obtained. Furthermore, when obtaining a low surface area support MgO, crystallization of the MgO can be promoted by forming a high partial pressure of water in the firing system at a temperature of 1000 ° C. or lower,
In this case, crystallization of MgO can be promoted by forming a high partial pressure of a gas (gas) such as CO ₂ instead of the partial pressure of water. As the atmosphere for the firing, an air atmosphere is usually used, but another gas, for example, an inert gas such as a nitrogen gas may be used. The firing time is 1 hour or more, preferably 3 hours or more, and the upper limit is not particularly limited, but is usually about 72 hours. The method is not limited to the firing method, and any method may be employed as long as MgO having such a low surface area can be obtained.

The carrier MgO according to the present invention has a high degree of crystallinity, the surface of the MgO is stabilized, and the MgO has a strong acid point suppressed as much as possible. And, with such stabilized MgO, MgO having only an acid point having an acid strength (Ho) of 2 or more and an amount of less than 0.03 mmol / g can be obtained. Therefore, by using MgO having a high degree of crystallinity, which has been calcined at a high temperature of 1000 ° C. or more, as a carrier for supporting a catalytic metal, the expression of strong acid sites is suppressed as much as possible, and a catalyst having a stable activity in which a carbon deposition reaction is suppressed is obtained. It becomes possible. The surface area of MgO used in the present invention is 0.01 to 5 m.
² / g, preferably 0.05 to ³ m ² / g. Carrier M
When the surface area of gO is higher than the above range, the amount of the supported catalyst metal increases, and the acid strength of the catalyst becomes too strong, so that the acid properties of the catalyst surface become unsatisfactory. on the other hand,
If the surface area of the support MgO is smaller than the above range, the amount of the supported catalyst metal is too small, and a catalyst having a sufficient activity cannot be obtained.

In general, it is well known that the surface area of a metal oxide and its crystallite size are substantially inversely proportional. Therefore, the specific surface area of MgO specified in the present invention can be specified by its particle size.
For example, the crystallite size of MgO having a specific surface area of 5 m ² / g or less can be calculated from the density and specific surface area of MgO by assuming that the particles are spherical or cubic uniform particles. This method is described in the document “Catalyst Configuration 3 (Characterization of Solid Catalyst)” (published in 1985, Kodansha Scientific, edited by the Catalysis Society of Japan, p. 203). For example, a specific surface area of 5 m ² fired at 1010 ° C.
/ G of MgO has a crystallite size of 3500 °.

The crystallite size of MgO can also be measured by using an X-ray diffraction method. When the crystallite size of MgO having a surface area of 5 m ² / g or less in the present specification was measured by a “line broadening” method using an X-ray diffraction method, the value was 900 ° or more. As a measuring device, an X-ray diffractometer “XRD-6000” manufactured by Shimadzu Corporation was used. When measured using metal Si as a standard substance, the crystal size of MgO is 2θ of MgO = 42.7.
And the half value width of the diffraction peak at 28.4 ° of 2θ of Si MgO = 28.4 °. The measurement conditions in the X-ray diffraction measurement are shown below. X-ray tube: Cu (λ = 1.5406 °), tube voltage: 4
0.0 kV, tube current: 30.0 mA, measurement range: 40.
0 to 80.0 °, step width: 0.02 °, counting time:
0.6 seconds, slit: DS (divergent slit) = 0.5
°, SS (anti-scattering) = 0.5 °, RS (light receiving) = 0.
Details of this line broadening method are described in the document "Experimental Chemistry Chemistry 4 (Solid State Physical Chemistry)" (published in 1956, Maruzen, edited by The Chemical Society of Japan, pages 238 to P250). .

In the second step (catalyst metal loading step), the carrier magnesium oxide obtained as described above is subjected to an equilibrium adsorption method using an aqueous solution containing a catalyst metal.
The catalyst aqueous solution is supported in eight or more alkali regions.
In the present invention, rhodium and / or ruthenium are used as the catalyst metal. In the supporting step, the catalytic metal is supported on the carrier magnesium oxide in the form of an aqueous solution. In this case, the catalytic metal is used in the form of a water-soluble compound. Examples of such compounds include halides, nitrates, sulfates, organic acid salts (such as acetates), and complex salts (chelates). An equilibrium adsorption method is employed for supporting the catalyst metal aqueous solution on the carrier MgO. In this method, a carrier is immersed in a catalyst aqueous solution, and the catalyst metal in the aqueous solution is adsorbed and supported on the carrier under equilibrium conditions. In this case, the time for supporting the catalyst metal on the carrier (immersion time) is 1 hour or more, preferably 3 hours or more, and the upper limit is not particularly limited, but is usually about 48 hours. The details of this equilibrium adsorption method are described in the document "Catalyst Preparation Chemistry" (published in 1980, Kodansha Scientific, P49).

When the catalyst metal is supported on the carrier MgO as described above, the pH of the catalyst aqueous solution is set to an alkaline region of 8 or more, preferably 8.5 or more. The upper limit is not particularly limited, but is usually about pH 13.
To adjust the pH of the aqueous solution, an alkaline substance such as sodium hydroxide, potassium hydroxide, calcium hydroxide, or magnesium hydroxide, or aqueous ammonia is used. In the present invention, the amount of the catalyst metal supported on the support MgO is 10 to 5000 watts on the support MgO in terms of the catalyst metal.
tppm, preferably 100 to 2000 wtppm. When the amount of the supported catalyst metal is larger than the above range, the cost of the catalyst is increased, and the carbon deposition activity of the catalyst is increased, and the amount of deposited carbon is increased when the catalyst is used. On the other hand, if it is less than the above range, sufficient catalytic activity cannot be obtained. The adjustment of the amount of the supported catalyst metal can be performed by adjusting the conditions for supporting the aqueous solution of the catalyst metal on the carrier MgO, for example, the concentration of the catalyst metal in the aqueous solution, the surface area of the carrier MgO, and the like.

In the third step (drying step), the catalyst metal-supported MgO obtained by supporting the catalyst metal in the form of an aqueous solution on the carrier MgO as described above is treated at 35 ° C.
Hold at the following temperature for 6 hours or more and dry. The preferred drying temperature is from 10 to 25C. The drying time may be at least 6 hours, preferably at least 12 hours, and the upper limit is not particularly limited, but is usually about 72 hours. By such a drying treatment, rapid evaporation of water from MgO is avoided, and as a result, the catalyst metal is supported on the carrier MgO in a highly dispersed state without agglomeration. If the drying temperature and the drying time deviate from the above ranges, a catalyst containing a highly dispersible catalytic metal cannot be obtained.

The dried product obtained as described above is fired in a fourth step at a high temperature of 200 ° C. or more for one hour or more. In this case, air is usually used as the firing atmosphere, but another gas (such as an inert gas) may be used. The firing temperature is 200 ° C. or higher, preferably 50 ° C.
0 ° C. or higher, and the upper limit is not particularly limited,
Usually, it is about 1100 ° C. The preferred firing time is 2 hours or more, more preferably 3 hours or more, and the upper limit is not particularly limited, but is usually about 24 hours. By this secondary calcination, the thermal stability of the catalyst metal is enhanced, and a catalyst with good thermal stability can be obtained.

In order to reduce the catalyst cost, the amount of the catalyst metal supported on the carrier is reduced as much as possible, and at the same time, the catalyst metal particles supported on the carrier are aggregated so as to exhibit sufficient reaction activity. It is necessary to reduce the particle size as much as possible and to make the particles fine. According to the study of the present inventors, the crystallization of the carrier MgO was enhanced to increase its specific surface area to 5 m ^2.
/ G or less, the amount of the catalyst metal supported on the carrier MgO is kept as small as 10 to 5000 wtppm, and the catalyst metal is supported on the carrier MgO by the equilibrium adsorption method. The catalyst metal is supported uniformly in the form of an aqueous solution slowly over a long period of time under equilibrium conditions, and after that, when slowly dried at a temperature of 35 ° C. or less, the catalyst metal is uniformly supported and used as a catalyst for hydrocarbon reforming. It has been found that inexpensive catalysts with sufficient activity can be obtained.

Various changes can be made in the above-described method for preparing the catalyst. For example, the method for supporting the catalyst metal on the carrier magnesium oxide is not limited to the equilibrium adsorption method, and other methods such as a conventional impregnation method, an immersion method, and an ion exchange method can be used. In addition, in the case of drying after supporting the aqueous solution containing the catalyst metal on the carrier magnesium oxide, a heating condition of about 35 to 200 ° C. may be employed in some cases. Depending on the case, it may be performed at a temperature of about 200 to 800 ° C.

When the catalyst is prepared according to the present invention, the magnesium oxide for forming the catalyst carrier is preferably used as a magnesium oxide compact formed by mixing a molding aid with magnesium oxide. By using this molding aid, the workability during molding is improved and the strength of the obtained molded body is improved. As a molding aid in this case,
(I) carbon (carbon), (ii) a fatty acid having 12 to 22 carbon atoms or a magnesium salt thereof, (iii) carboxymethyl cellulose (CMC) or a magnesium salt thereof, and (iv) at least one kind selected from polyvinyl alcohol. Preferably, a compound is used. These molding aids are usually used in powder form. As the carbon, graphite, carbon black, activated carbon and the like are used. Examples of the fatty acid include lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid and the like.

In order to produce the above-mentioned magnesium oxide molded body for a catalyst carrier, a molding aid is added to powdered magnesium oxide, and the mixture is uniformly mixed, and then the mixture is molded into a required shape. The average particle size of the powdered magnesium oxide is 1 to 10
It is 00 μm, preferably 10 to 100 μm. on the other hand,
The molding aid has an average particle size of 1 to 1000 μm, preferably 1 to 1000 μm.
0 to 100 μm. The amount of the molding aid added to the magnesium oxide is 0.1 to 5% by weight, preferably 0.5 to 3.0% by weight, based on the total amount of the magnesium oxide and the molding aid. When forming a mixture of the magnesium oxide and a molding aid, the molding conditions are usually 3000 to 100 kg / cm ² G at ordinary temperature, preferably 2000
Pressure of ~200kg / cm ² G is employed. As a molding method, a press molding method is adopted, but a tableting method or the like can also be adopted. The shape of the molded body is not particularly limited, and may be any shape as long as it is used for a normal catalyst. Such shapes include tablets, columns, rings, hollow cylinders, and the like. The size of the formed body is usually 3 to 30 mm, preferably 5 to 25 mm in terms of its major axis, but an appropriate size may be adopted according to the catalyst bed.

The magnesium oxide molded article according to the present invention has excellent mechanical strength after firing, and is usually 30 to 70 k
g / piece radial compressive strength. Therefore, such a molded body has good handleability and is not easily broken during firing. In addition, when the crystallinity of MgO is low, the magnesium oxide compact is usually first fired at a high temperature of 1000 ° C. or higher to obtain a desired carrier magnesium oxide.
By this primary firing, the molding aid in the molded body is oxidized and removed. The magnesium oxide thus obtained is suitable as a carrier magnesium oxide used for preparing the catalyst of the present invention.

In the catalyst of the present invention obtained as described above, the amount of the supported catalyst metal is 1 to the supported MgO.
0 to 5000 wtppm, preferably 100 to 2000
wt ppm, and its specific surface area is 0.01 to ⁵ m ² /
g, preferably 0.05 to ³ m ² / g. The specific surface area of the catalyst and MgO in the present specification is:
It was measured at a temperature of 15 ° C. by the “BET” method, and the measuring device was “SA-1” manufactured by Shibata Kagaku Co., Ltd.
00 "was used.

The catalyst of the present invention obtained as described above has favorable acidic properties as a catalyst for hydrocarbon reforming. When a large number of strong acid sites are present on the catalyst surface, a carbon deposition reaction, which is a side reaction, is promoted on the acid sites, carbon is deposited, and the deposited carbon causes catalyst poisoning.

The catalyst of the present invention generally has an acid strength (Ho) of only acid sites greater than 2, preferably 3.3 or higher, and its content is less than 0.03 mmol / g, preferably less than 0.03 mmol / g. Is 0.02 mmol / g or less. The adjustment of the acid strength (Ho) can be performed by adjusting the temperature and the time when the support MgO is subjected to the first firing. In the catalyst of the present invention, the expression of strong acid sites is suppressed, and the carbon deposition activity is greatly suppressed.

The acid strength (Ho) referred to in the present specification is:
It is expressed as the ability of the catalyst to give a proton to the basic indicator (B ⁻ ) and is expressed by the following formula. ^{_{Ho = pKa (= pK B -}} H +) + log [B] / [B - H +] (1) In the formula, K _B ^- _H ⁺ is a basic indicator B ^- the reaction of the acid point H ⁺ B Thus, the dissociation constant of the acidic form B ^- H ⁺ in the reaction for producing the acidic form (B ^- H ⁺ ) of the basic indicator is shown. ^{[B] / [B - H} +] is, B ^- and B ^- shows the H ⁺ concentration ratio of. As strong acid sites, pK _B ^- the Ho value because more protonate a small indicator _H ⁺ decreases.

In the present specification, the acid strength is measured as follows. (Method of Measuring Acid Strength) The acid strength Ho (Hammett index) function in this specification is an acid strength function, which is described in “Catalyst Experiment Handbook” edited by the Catalysis Society of Japan (published in 1986, Kodansha Scientific), p. 172 “Benesi method”
Is measured by Addition of an indicator whose pKa is known to the catalyst and discoloration indicate that Ho has an acid point less than its pKa. When a predetermined amount of butylamine, which is a basic molecule, is adsorbed to acid sites and titrated with an indicator having a different pKa, the number of acid sites is determined from the amount of butylamine as p
The acid strength can be measured from the value of Ka. The measurement temperature is room temperature.

Using the catalyst of the present invention, synthesis gas (hydrogen and
Gas mixture with carbon oxides) in the presence of a catalyst
, In which hydrocarbon and steam and / or carbon dioxide
(CO _Two) Or react hydrocarbons with oxygen
It should be done. Hydrocarbons include methane, ethane,
Lower hydrocarbons such as lopan, butane and naphtha are used
Preferably, methane is used. In the present invention
Uses natural gas (methane gas) containing carbon dioxide as a raw material
Can be used advantageously. Methane and carbon dioxide
(CO_Two) (CO_TwoReforming)
In this case, the reaction is represented by the following formula.

Embedded image In the case of a method of reacting methane and steam (steam reforming), the reaction is represented by the following equation.

Embedded image

CO_TwoThe reaction in reforming
The temperature is 500-1200 ° C., preferably 600-100.
0 ° C., the reaction pressure is pressurized, 5-40 kg
/ cm^TwoG, preferably 5 to 30 kg / cm^TwoG. Ma
When this reaction is carried out in a fixed bed system, the gas space velocity
The degree (GHSV) is 1,000 to 10,000 hours^-1, Good
Preferably 2,000-8,000hr^-1It is. Coking coal
CO for hydrogen hydride _TwoIndicating the usage ratio of
CO per mole of carbon in carbon dioxide_Two20-0.5 mol, preferred
Or 10 to 1 mol. Steam Reformi
The reaction temperature is 600-1200 ° C.
Preferably, the temperature is 600 to 1000 ° C., and the reaction pressure is
Pressure, 1-40kg / cm^TwoG, preferably 5 to 30
kg / cm^TwoG. This reaction is carried out in a fixed bed system.
The gas space velocity (GHSV) is 1,000-
10,000hr ^-1, Preferably 2,000-8,000.
0 hr^-1It is as follows. Steam use for raw hydrocarbons
In terms of the usage ratio, the amount of sulfur per mole of carbon
Team (H _TwoO) 0.5-5 mol, preferably 1-2 mol
, More preferably 1 to 1.5 moles. Departure
If steam reforming is performed due to light,
Thus, the steam (H_Two
Even if O) is kept at 2 mol or less, carbon deposition is suppressed,
Syngas can be produced industrially advantageously. Conventional
In the case of the above, 2 to 5 moles per mole of carbon of the starting hydrocarbon
Considering that the steam needed to be
Smooth reforming reaction by using lower steam
The great industrial advantage of the catalyst of the present invention.
Is a point. The catalyst of the present invention is obtained by adding steam and C
O_TwoUsed as a catalyst in the reaction of a mixture of
It is. In this case, steam and CO_TwoEspecially the mixing ratio with
Although not restricted, generally H_TwoO / CO_TwoIn molar ratio,
0.1 to 10.

In the case of reacting a hydrocarbon with oxygen using the catalyst of the present invention, the hydrocarbon may be a hydrocarbon as described above, but is preferably methane.
As the oxygen source, oxygen, air, or oxygen-enriched air is used. In the present invention, natural gas (methane gas) containing carbon dioxide can be advantageously used as a reaction raw material. When reacting methane and oxygen, the reaction is represented by the following equation.

Embedded image In this partial oxidation of hydrocarbons, the reaction temperature is 50
0 to 1500 ° C., preferably 700 to 1200 ° C., and the reaction pressure is pressurized, 5 to 50 kg / cm
² G, preferably 10 to 40 kg / cm ² G. When this reaction is carried out in a fixed bed system, the gas hourly space velocity (GHSV) is 1,000 to 50,000 hr ^-1 , preferably 2,000 to 20,000 hr ^-1 . The ratio of the number of moles of carbon to the number of moles of oxygen in the raw material hydrocarbon is expressed as C / O ₂ , which is 4%.
-0.1, preferably 2-0.5. In addition, since the partial oxidation method is a large exothermic reaction, an autothermic reaction method can be adopted by adding steam or carbon dioxide to the raw material. The various reactions using the catalyst of the present invention are carried out in various catalyst systems such as a fixed bed system, a fluidized bed system, a suspension bed system, and a moving bed system, but are preferably carried out in a fixed bed system.

[0028]

Next, the present invention will be described in more detail with reference to examples.

Example 1 A commercially available magnesium oxide having a purity of 98.7 wt% or more (M
gO) powder was mixed with 3.0% by weight of carbon as a sliding material, and 1/8 inch pellets formed into tablets were fired in air at 1060 ° C. for 3 hours (hours), and this was used as a catalyst carrier MgO (A). Using. Next, 3.9 wt% R
The sample was immersed in a rhodium (III) acetate aqueous solution containing h for 26 h (hour). The pH of the aqueous solution was adjusted to 9.7 using an aqueous solution of magnesium hydroxide. Thus, R
After equilibrium adsorption of h on the catalyst support MgO (A), filtration was performed to obtain a catalyst support MgO (A) in which Rh was adsorbed in the form of an aqueous solution. The amount of Rh supported in this case is 3750 wtppm relative to the carrier MgO (A) in terms of Rh metal.
Next, the carrier MgO (A) to which Rh was adsorbed was dried in air at a temperature of 35 ° C. for 52 hours, and then dried in air.
It was calcined at 50 ° C. for 3 hours to obtain the catalyst (A) of the present invention. This catalyst (A) was prepared by using Rh as Rh metal and
It contains 750 wtppm and its surface area is 1.2
m ² / g. The acid point is determined by the acid strength (Ho).
Consists of only 3.3 or more acid sites and has a content of 0.01
mmol / g.

Example 2 A commercially available magnesium oxide having a purity of 98.0% by weight (Mg)
A 1/8 inch pellet of MgO formed using O) was fired in air at 1000 ° C. for 2 hours (hour), and this was used as a catalyst support MgO (B). Next, a ruthenium (III) chloride aqueous solution containing 0.1 wt% of Ru was added for 19 hours.
(Time) Dipped. The pH of the aqueous solution was adjusted to 9.7 using an aqueous solution of magnesium hydroxide. In this way, after Ru is equilibrium-adsorbed on the catalyst support MgO (B),
Filtration, catalyst support MgO adsorbing Ru as an aqueous solution
(B) was obtained. In this case, the supported amount of Ru is 125 wtppm in terms of Ru metal, based on the carrier MgO (B). Next, the MgO (B) carrier on which Ru was adsorbed was dried in air at a temperature of 30 ° C. for 72 hours, and then calcined in air at 860 ° C. for 2.5 hours to obtain a catalyst (B) of the present invention. This catalyst (B) is obtained by using Ru as a Ru metal and supporting Mg.
It was contained at a rate of 125 wtppm with respect to O (B), and its surface area was 4.8 m ² / g. The acid sites consisted only of acid sites having an acid strength (Ho) of 3.3 or more, and the content was 0.03 mmol / g.

Example 3 A commercially available magnesium oxide having a purity of 99.9% by weight (Mg)
O) mixed with 2.5 wt% magnesium stearate and molded into 1/8 inch MgO pellets in air.
Firing at 200 ° C. for 2.5 hours (hours)
Used as gO (C). Next, the rhodium (III) acetate aqueous solution containing 2.6 wt% Rh is added for 26 h (hour).
Dipped. The pH of the aqueous solution was adjusted to 9.7 using an aqueous solution of magnesium hydroxide. In this way, after Rh is equilibrium-adsorbed on the catalyst support MgO (C), it is filtered,
A catalyst support MgO (C) in which Rh was adsorbed in the form of an aqueous solution was obtained. The amount of supported Rh in this case is 1750 wtppm relative to the carrier MgO (C) in terms of Rh metal. Next, the MgO (C) carrier on which Rh has been adsorbed is dried in air at a temperature of 20 ° C. for 34 hours.
It was calcined at 0 ° C. for 3.5 hours to obtain the present catalyst (C). This catalyst (C) contains 1750 wtppm of Rh as Rh metal with respect to the carrier MgO, and has a surface area of 0.1 ppm.
It was 2 m ² / g. The acid point is determined by the acid strength (H
o) consists only of 3.3 or more acid sites, and its content is 0.3.
002 mmol / g.

Reaction Example 1 30 cc of the catalyst (A) prepared in Example 1 was charged into a reactor, and a methane CO ₂ reforming test was carried out. The catalyst, after 1h reduction treatment beforehand with H ₂ 900 ° C. in a stream, CH _4: CO ₂ molar ratio _{= 1: 0.4, CH 4:} H 2 O molar ratio = 1: 0.85 of the raw material gas At a pressure of 20 kg / cm
² G, temperature 820 ° C, methane-based GHSV = 4000
The treatment was performed under the conditions of hr ^-1 . C 5 hours after the start of the reaction
H ₄ conversion is 50% (CH ₄ of equilibrium conversion = 50% under the experimental conditions), and the conversion of CH ₄ after 1200h elapsed from the start of the reaction was 50%. Where CH ₄
Is defined by the following equation: CH ₄ conversion (%) = (A-B ) / A × 100 A: CH in the feed ₄ moles B: CH ₄ moles in the product

Reaction Example 2 30 cc of the catalyst (B) prepared in Example 2 was charged into a reactor, and a methane CO ₂ reforming test was carried out. The catalyst was previously subjected to a reduction treatment at 900 ° C. for 1 hour in an H ₂ gas stream, and then a raw material gas having a CH ₄ : CO ₂ molar ratio = 1: 1 was applied to the catalyst at a pressure of 1: 1.
0 kg / cm ² G, temperature 840 ° C, GHS based on methane
The treatment was performed under the condition of V = 5000 hr ^-1 . 5 from the start of the reaction
After ₄ hours, the CH ₄ conversion was 65% (C under the experimental conditions).
The equilibrium conversion of H ₄ = 65%), and the conversion of CH ₄ after 460 hours from the start of the reaction was 65%.

Reaction Example 3 30 cc of the catalyst (C) prepared in Example 3 was charged into a reactor, and a methane CO ₂ reforming test was carried out. The catalyst was previously subjected to a reduction treatment at 900 ° C. for 1 hour in an H ₂ gas stream, and then a raw material gas having a CH ₄ : CO ₂ molar ratio of 1: 1 was applied at a pressure of 2
0 kg / cm ² G, temperature 840 ° C, GHS based on methane
The treatment was performed under the condition of V = 3500 hr ^-1 . 5 from the start of the reaction
After ₄ hours, the conversion of CH ₄ is 53% (C under the experimental conditions).
The equilibrium conversion of H ₄ = 53%), and the conversion of CH ₄ 250 hours after the start of the reaction was 53%.

[0035]

According to the present invention, it is possible to obtain an inexpensive hydrocarbon reforming catalyst in which the amount of catalyst metal carried is extremely small and the carbon deposition activity is significantly suppressed.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yukitaka Wada 2-1-1, Tsurumichuo, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture Inside Chiyoda Kako Construction Co., Ltd. (72) Inventor Mitsunori Shimura Tsurumi-chuo, Tsurumi-ku, Yokohama-shi, Kanagawa 1-chome No. 1 Chiyoda Kako Construction Co., Ltd. F-term (reference) 4G040 EA03 EA06 EC03 EC05 EC08 4G069 AA03 BA06A BA06B BA06C BC70A BC70B BC70C BC71A BC71B BC71C CC04 DA05 FA02 FB06 FB57 FC02 FC07 FC08 FC09 FC1000

Claims (6)

[Claims] 1. A carbonization method comprising: supporting rhodium and / or ruthenium on a carrier magnesium oxide having a specific surface area of 5 m ² / g or less, in a ratio of 10 to 5000 wt ppm in terms of metal, and then calcining. A method for preparing a catalyst for reforming hydrogen. 2. (i) a first step of obtaining a carrier magnesium oxide having a specific surface area of 5 m ² / g or less, and (ii) a water-soluble rhodium compound and / or a carrier magnesium oxide obtained in the first step. Using an aqueous solution containing a ruthenium compound, rhodium and / or ruthenium can be converted to a metal in an amount of 10 to 5000 in terms of metal in an alkaline region having a pH of 8 or more by an equilibrium adsorption method.
(iii) a third step of drying the rhodium and / or ruthenium-supported magnesium oxide obtained in the second step, and (iv) a dry state obtained in the third step. A method for preparing a catalyst for reforming hydrocarbons, comprising a fourth step of calcining magnesium oxide carrying rhodium and / or ruthenium. 3. A first step for obtaining a carrier magnesium oxide having a specific surface area of 5 m ² / g or less, and (ii) a water-soluble rhodium compound and / or a carrier magnesium oxide obtained in the first step. Using an aqueous solution containing a ruthenium compound, rhodium and / or ruthenium can be converted to a metal in an amount of 10 to 5000 in terms of metal in an alkaline region having a pH of 8 or more by an equilibrium adsorption method.
a second step of supporting the rhodium and / or ruthenium-supported magnesium oxide obtained in the second step at a temperature of 35 ° C. or lower for at least 6 hours or more; A method for preparing a hydrocarbon reforming catalyst, comprising a fourth step of calcining the dried rhodium and / or ruthenium-supported magnesium oxide obtained in the three steps. 4. A (i) first step of obtaining a carrier magnesium oxide having a specific surface area of 5 m ² / g or less, (ii) a water-soluble rhodium compound and / or a water-soluble rhodium compound added to the carrier magnesium oxide obtained in the first step. Using an aqueous solution containing a ruthenium compound, rhodium and / or ruthenium can be converted to a metal in an amount of 10 to 5000 in terms of metal in an alkaline region having a pH of 8 or more by an equilibrium adsorption method.
a second step of supporting the rhodium and / or ruthenium-supported magnesium oxide obtained in the second step at a temperature of 35 ° C. or less for at least 6 hours or more; 4. A method for preparing a hydrocarbon reforming catalyst, comprising a fourth step of calcining the dried rhodium and / or ruthenium-supported magnesium oxide obtained in the three steps at a high temperature of 200 ° C. or higher. 5. The carrier magnesium oxide having a specific surface area of 5 m ² / g or less is obtained by calcining magnesium oxide at a high temperature of 1000 ° C. or more.
4. Any of the four methods. 6. A mixture of magnesium oxide and a molding aid, wherein the molding aid comprises (i) carbon, and (ii) carbon number 12
Or at least one selected from fatty acids or magnesium salts thereof, (iii) carboxymethyl cellulose or magnesium salts thereof, and (iv) polyvinyl alcohol, and the amount of addition is 0.1 to 5% by weight. A magnesium oxide molded body for forming a catalyst carrier used in the method according to any one of claims 1 to 5.