JP2002126531A - Catalyst for steam reforming reaction of methane and method for steam reforming of methane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a catalyst capable of efficiently suppressing a carbon deposition reaction, regarding a catalyst to be employed for a steam reforming method of methane. SOLUTION: The catalyst for steam reforming reaction of methane is a catalyst for reacting methane with steam to produce hydrogen and carbon monoxide and is characterized in that the catalyst is alumina containing an ultrafine nickel particle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a catalyst for a steam reforming reaction of methane (steam reforming) and a method for steam reforming of methane using the catalyst.

[0002]

2. Description of the Related Art A method of reacting methane with steam in the presence of a catalyst to produce steam and carbon monoxide is known as a hydrogen reforming method. In this method, when the usage ratio of steam becomes low, for example, when the steam / methane molar ratio becomes lower than 1.4, the precipitation reaction of carbon is remarkably accelerated, and problems such as clogging of the reaction tube and reduction in catalytic activity occur. .

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a catalyst for use in a methane steam reforming method which effectively suppresses a carbon deposition reaction and a methane steam reforming method using the catalyst. Make it an issue.

[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, there is provided a catalyst for a steam reforming reaction of methane for producing methane and hydrogen monoxide by reacting methane with steam, the catalyst comprising alumina containing nickel ultrafine particles. Is provided. Further, according to the present invention, in a steam reforming method for methane in which methane is reacted with steam in the presence of a catalyst to generate hydrogen and carbon monoxide, the methane is used as the catalyst. Is provided.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The catalyst of the present invention comprises alumina containing ultrafine nickel particles. In this catalyst, the content of the nickel ultrafine particles is 1 to 30 with respect to the catalyst.
%, Preferably 5 to 20%. The average particle size of the nickel ultrafine particles is 10 to 200 °, preferably 30 to 100 °.
It is. In the catalyst of the present invention, the nickel particle size distribution is sharp, and when the average particle size is defined as M, the nickel particle size in the range of 0.8M to 1.2M is 8%.
0% or more are distributed. Further, the interaction between nickel and alumina is strong, and the nickel fine particles are made of alumina (N
(shows an electron-withdrawing property with respect to i). This is confirmed by the TPR. That is, looking at the TPR spectrum of the catalyst of the present invention, the catalyst has a temperature in the range of 770 to 776K, usually about 773K.
Has a peak due to NiO → Ni, and this peak is shifted to a higher temperature side than the peak in the case of a normal nickel / alumina catalyst obtained by the impregnation method. The shape of the catalyst can be various shapes such as a powder shape, a pellet shape, and a spherical shape, and is not particularly limited.

To prepare the catalyst of the present invention, first, a water-in-oil microemulsion containing ultrafine nickel hydroxide is prepared. In this emulsion, an aqueous solution of a water-soluble nickel compound such as nickel nitrate is added to a water-insoluble solvent containing a surfactant, and the mixture is stirred at high speed. in this case,
As the surfactant, for example, the average number of moles added is 5-2.
5, preferably 5 to 20 polyoxyethylene nonylphenols can be used. The amount used is 0.1 to 0.5 mol, preferably 0.2 to 0.3 mol, per liter of the water-insoluble solvent. The water-insoluble solvent has a boiling point of 60 to 200 ° C, preferably 60 to 17 ° C.
0 ° C., for example, alcohols having 6 to 10 carbon atoms (hexanol, heptanol, octanol, cyclohexanol, etc.) and hydrocarbons having 6 to 12 carbon atoms (hexane, heptane, octane, cyclohexane, benzene,
Toluene and the like). In the aqueous solution containing the nickel compound, the concentration of the nickel compound is 0.1.
It is 1 to 10%, preferably 1 to 5%. The amount of the aqueous solution containing the nickel compound added to the water-insoluble solvent is 1 to 200 cc, preferably 20 to 1 liter of the water-insoluble solvent.
割 合 100 cc. The mixing temperature of the water-insoluble solvent and the aqueous solution containing the nickel compound is 5 to 50C, preferably 20 to 50C.

[0007] As described above, a microemulsion in which an aqueous solution containing a nickel compound is dispersed as ultrafine water droplet particles in a water-insoluble solvent is obtained. The average particle size of the water droplet particles in this emulsion is 10 to 300 °, preferably 20 to 150 °.

Next, a trialkylamine is added to the microemulsion and stirred to react with a nickel compound (nitrate) contained in the microemulsion to produce nickel hydroxide ultrafine particles. Thereafter, an aluminum alkoxide is added under stirring, and the mixture is hydrolyzed in the emulsion. As the trialkylamine, a trialkylamine having a lower alkyl group having 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms is used, and its addition amount is an amount sufficient to convert the nickel compound to a hydroxide. Should be fine. As the aluminum alkoxide, an aluminum trialkoxide having a lower alkyl group having 1 to 6, preferably 1 to 3 carbon atoms can be used. The amount is represented by the atomic ratio of nickel to aluminum contained in the emulsion [Ni] / [Al],
The ratio is 0.01 to 0.31, preferably 0.05 to 0.22. When aluminum alkoxide is added to an emulsion containing a nickel compound, the aluminum alkoxide is preferably dissolved in a water-insoluble solvent and added as a solution.

By the hydrolysis of the above-mentioned aluminum alkoxide, an emulsion containing an aluminum hydroxide containing nickel hydroxide in the form of ultrafine particles is obtained. The aluminum hydroxide is separated from the mother liquor by a solid-liquid separation method such as centrifugation, washed, dried at a temperature of about 80 ° C., and then 350 to 650 ° C. in air, preferably 400 to 5 ° C.
Bake at 00 ° C. Thus, a catalyst made of alumina containing ultrafine nickel oxide is obtained. When this catalyst is used in the reaction, it is preferable to catalyze the catalyst in advance with hydrogen to reduce its nickel oxide to metallic nickel.

In order to carry out steam reforming of methane using the catalyst of the present invention, a mixture of methane and steam may be brought into contact with the catalyst of the present invention. In this case, the ratio of steam to methane is 0.5 mole or more, preferably 1 to 3 moles of steam per mole of methane. The reaction temperature is 550-8
The temperature is 50 ° C, preferably 600 to 800 ° C. By this reaction, a reaction product containing hydrogen and carbon monoxide is obtained.

[0011]

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

Example 1 In a beaker having an internal volume of 1000 ml, 500 ml of a 0.3 M solution of polyoxyethylene (average addition mole number: 20) nonylphenyl ether 1-hexanol was added.
30 ml of a 25 M aqueous nickel nitrate solution was added, and the mixture was stirred with a magnetic stirrer at 50 ° C. to prepare a microemulsion. This microemulsion is of the water-in-oil type, the diameter of the water droplet particles is calculated to be 66 °,
The average number of nickel ions contained in one water droplet is 23
Is calculated. To this microemulsion, 3 cc of commercially available triethylamine was added and stirred well at 50 ° C. for 10 minutes to form nickel hydroxide ultrafine particles. Thereafter, at a temperature of 50 ° C. under stirring, 40 g of aluminum triisopropoxide was added to 300 m of 2-hexanol.
The mixture which had been previously mixed and stirred was added to 1 and hydrolyzed for 1 hour. Next, the contents of the beaker were cooled to room temperature, and the mother liquor was separated by centrifugation.
Washed three times with propanol. The purified precipitate was dried at 80 ° C. for 12 hours and calcined at 400 ° C. for 5 hours (heating rate 2 ° C./min) under air flow. As a result, 9.2 g of an alumina gel (catalyst I) containing 5.0% by weight of nickel was obtained. In order to evaluate the performance of the 5.0 wt% nickel-containing alumina gel catalyst I prepared as described above, the catalyst I was molded by a molding machine into pellets having a particle size of 16 to 28 mesh. 2 g was charged into a reaction tube having an inner diameter of 8 mm, and hydrogen reduction was first performed at 600 ° C. for 2 hours under a hydrogen flow. Table 1 shows the physical properties and carbon residue of Catalyst I after hydrogen reduction. After hydrogen reduction, a steam reforming reaction of methane was performed. That is, a reaction tube is installed in an electric furnace whose temperature can be controlled within a temperature range of 1 ° C., and a mixed gas of methane: steam: argon = 10: 10: 1 (molar ratio) is fed into the reaction tube. Reacted. The reaction pressure was normal pressure, the catalyst layer temperature was 600 ° C., and the mixed gas flow rate was 116 cc / min. From this reaction experiment, it was confirmed that the catalyst of the present invention showed very small activity deterioration and maintained high activity for a long time.

Example 2 Using the dispersion of nickel hydroxide fine particles produced in Example 1 and aluminum triisopropoxide as raw materials,
In the same manner as in the above, an alumina gel (catalyst II) having a nickel content of 10.1 wt% was prepared. Table 1 shows the physical properties of the catalyst. Using this nickel-containing alumina catalyst, a catalyst performance evaluation test similar to that in Example 1 was performed. From this reaction experiment, it was confirmed that the catalyst of the present invention showed very small activity deterioration and maintained high activity for a long time.

Example 3 500 ml of a 0.3 M solution of polyoxyethylene nonylphenyl ether / 1-hexanol (average number of moles added: 10) was placed in a beaker having an internal volume of 1000 ml, and 30 ml of a 0.25 M nickel nitrate aqueous solution was added thereto. 55 ° C
The microemulsion was prepared by stirring under a magnetic stirrer. Subsequent operations were performed in the same manner as in Example 1 to prepare an alumina gel (catalyst III) having a nickel content of 10.2 wt%. Table 1 shows the physical properties of the catalyst. Using this nickel-containing alumina catalyst, a catalyst performance evaluation test similar to that in Example 1 was performed. From this reaction experiment, it was confirmed that the catalyst of the present invention showed very small activity deterioration and maintained high activity for a long time.

Example 4 In a beaker having an internal volume of 1000 ml, 500 ml of a 0.3 M solution of polyoxyethylene (average addition mole number: 5) nonylphenyl ether / 1-octanol was added.
30 ml of 25M nickel nitrate aqueous solution was added, and the mixture was stirred with a magnetic stirrer at 55 ° C. to prepare a microemulsion. The subsequent operation was performed in the same manner as in Example 1 to prepare an alumina gel (catalyst IV) having a nickel content of 10.0% by weight. Table 1 shows the physical properties of the catalyst. Using this nickel-containing alumina catalyst, a catalyst performance evaluation test similar to that in Example 1 was performed. From this reaction experiment, it was confirmed that the catalyst of the present invention showed very small activity deterioration and maintained high activity for a long time.

Comparative Examples 1, 2, and 3 A 0.25 M aqueous solution of nickel nitrate and ion-exchanged water were put in an evaporating dish, and 5 g of alumina gel previously prepared in a microemulsion was added thereto, followed by stirring for 1 hour. After being left, it was dried in a vacuum dryer for 3 hours, and then dried in a dryer at 80 ° C. for 12 hours. Thereafter, firing and hydrogen reduction were performed under the same conditions as in Example 1. Thus, an alumina gel (catalyst A) having a nickel carrying amount of 5 wt% (catalyst A), an alumina gel of 10 wt% (catalyst B), and an alumina gel of 20 wt% (catalyst C) were prepared. Table 1 shows the physical properties of the catalyst. Using these alumina-supported nickel catalysts, the same catalyst performance evaluation test as in Example 1 was performed. From this reaction experiment, it was confirmed that the activity of each of the comparative catalysts was greatly degraded, and the activity rapidly decreased with time.

[0017]

[Table 1]

In Table 1, S _BET indicates the BET surface area of the catalyst. However, the catalysts A to C show the BET surface area of alumina. The amount of carbon is 873K, H ₂ O
It shows the amount of carbon remaining on the catalyst after continuing the reaction under the conditions of / CH ₄ = 1 and GHSV = 35000 h ⁻¹ . In this case, the reaction duration is 4 in the case of catalysts I to IV.
0 hours and 20 hours for catalysts AC.

As can be seen from Table 1, the average particle size of nickel of the catalyst by the microemulsion method (ME method) according to the present invention is 40 to 140 ° (4 nm to 1 nm).
4 nm), which is extremely small and contained in the catalyst in the form of ultrafine particles. Also, the nickel particle size distribution is very sharp. As can be seen by comparing inventive catalysts I-IV with comparative catalysts AC, all of the inventive catalysts maintain a high activity over time.

[0020]

The catalyst of the present invention has a very low carbon deposition property and maintains a high activity for a long time. Therefore, by using the catalyst of the present invention, it is possible to carry out steam reforming of methane while maintaining a high conversion rate for a long time.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Teruaki TAKO 2-20-22 Harada, Higashi-ku, Fukuoka City, Fukuoka Prefecture Maison d'Or Miyake Room 302 (72) Inventor Hiroki Hayashi 2-28, Hakomatsu, Higashi-ku, Fukuoka City, Fukuoka Prefecture No. 16 Cat Maison Room 101 F-term (reference) 4G040 EA03 EA06 EC02 EC08 4G069 AA03 AA08 BA01A BA01B BB02A BB02B BC68A BC68B CC17 DA06 EA01Y EA02Y EA04Y EB18Y EB19 FA01 FA02 FB06 EC08 EA08 EC08

Claims (3)

[Claims] 1. A methane steam reforming catalyst for producing methane and hydrogen monoxide by reacting methane with steam, comprising a catalyst containing alumina containing ultrafine nickel particles. Reaction catalyst. 2. The catalyst according to claim 1, wherein the proportion of nickel is 1 to 30% in the catalyst.
2. The catalyst of claim 1 wherein 3. A method of reacting methane with steam in the presence of a catalyst to produce hydrogen and carbon monoxide, wherein the catalyst according to claim 1 or 2 is used as the catalyst. Steam reforming method.