JP3316559B2 - Catalyst for syngas production by methanol decomposition and method for producing syngas - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a mixed gas of carbon monoxide and hydrogen (hereinafter referred to as synthesis gas) by decomposing methanol and a catalyst used for the method. More specifically, in producing synthesis gas by flowing gaseous methanol over a heated catalyst, a catalyst capable of producing synthesis gas with extremely high selectivity by suppressing the production of dimethyl ether, methyl formate, and the like. And a method for producing synthesis gas using the same.

[0002]

2. Description of the Related Art A technology for effectively utilizing warm waste heat discarded in large quantities from factories is a very important technology that can contribute to saving resources and energy and reducing the burden on the global environment such as global warming. In particular, technology that efficiently collects, stores, and transports low-temperature exhaust heat of about 200 ° C or less and uses it in commercial and residential areas has been used as a method of using low-temperature exhaust heat that has low utility value in terms of thermal efficiency. It is a heavy technology. Low-temperature waste heat is inefficiently recovered by a heat exchanger, and also has a heat loss during transportation, so its usage range is significantly limited.
In fact, it is almost impossible to use it. Therefore,
If this warm waste heat can be stored by an endothermic chemical reaction, and heat can be transported by transporting the reaction product, and heat can be regenerated by an exothermic reaction, an efficient heat storage and heat transport system can be realized. It becomes possible.

[0003] Methanol undergoes the following decomposition reaction to become synthesis gas.

## STR1 ## _{CH 3 OH → CO + 2H 2} + 21.7kcal / mol (1) At this time, to absorb the heat of 21.7kcal / mol in the above formula. If the generated synthesis gas is transported to a heat consuming area and methanol is synthesized again, heat equivalent to the above is generated.
An object of the present invention is to provide a catalyst capable of efficiently decomposing methanol in a system for storing and transporting heat utilizing the cycle of decomposition and resynthesis of methanol. The most important performance that the methanol decomposition catalyst should have in the present system is to allow the synthesis gas production reaction to proceed with high selectivity.

[0004] Decomposition of methanol is a reaction which is industrially used as a method for producing synthesis gas, but the conventional method is carried out at a high temperature of about 300 ° C. At a temperature of the warm exhaust heat, the catalyst shows little activity. In addition, when the reaction is allowed to proceed at about 200 ° C., there is a problem that dimethyl ether, methyl formate, carbon dioxide, methane and water are by-produced and the selectivity of carbon monoxide decreases (Wu-HsunCheng, Applied Catalysis A: Gene
ral 130 (1995) 13-30).

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a catalyst for producing a synthesis gas with an extremely high selectivity in a catalyst for a decomposition reaction of methanol, and to provide a method for producing a synthesis gas using the same. As an issue.

[0006]

Means for Solving the Problems The present inventors have solved the above problems.
As a result of intensive research to solve the problem, the present invention is completed
Reached. That is, according to the present invention, the decomposition reaction of methanol
In the synthesis gas production process,The following general formula Mg _6-2x Pd _2x M _Two (OH) ₁₆ CO _Three ・ MH _Two O (Where M is Al, Sc, Cr, Fe, Ga and Y
Represents at least one metal selected from the group consisting of
Indicates a small number, m indicates the percentage of water of crystallization, and 0 or
The above numbers are shown) Represented by Clay-like compoundObtained by firingComposite metal acid
Metal or palladium oxide contained in it
Hydrogenated complex metal oxide hydrogen reduced to indium?
Of syngas using a catalyst consisting of
A method (first method) is provided. According to the present invention,
IfThe following general formula Mg _6-2x Pd _2x M _Two (OH) ₁₆ CO _Three ・ MH _Two O (Where M is Al, Sc, Cr, Fe, Ga and Y
Represents at least one metal selected from the group consisting of
Indicates a small number, m indicates the percentage of water of crystallization, and 0 or
The above numbers are shown) Represented by Clay-like compoundObtained by firingComposite metal acid
Metal or palladium oxide contained in it
Hydrogenated complex metal oxide hydrogen reduced to indium?
Synthesis gas by methanol decomposition characterized by consisting of
(A first catalyst) is provided. In addition, the book
According to the invention, the synthesis gas by the methanol decomposition reaction
In the manufacturing method,The following general formula Mg _Three Rh _y M _1-y (OH) ₁₆ CO _Three ・ MH _Two O (Where M is Al, Sc, Cr, Fe, Ga and Y
At least one metal selected from the group consisting of
Indicates a small number, m indicates the percentage of water of crystallization, and 0 or
The above numbers are shown) Represented by Clay-like compoundObtained by firingComposite metal acid
Metal oxide or rhodium oxide contained in it
From hydrogenated composite metal oxides
For producing synthesis gas, characterized by using a catalyst
(Second method) is provided. Furthermore, according to the present invention,
IfThe following general formula Mg _Three Rh _y M _1-y (OH) ₁₆ CO _Three ・ MH _Two O (Where M is Al, Sc, Cr, Fe, Ga and Y
At least one metal selected from the group consisting of
Indicates a small number, m indicates the percentage of water of crystallization, and 0 or
The above numbers are shown) Represented by Clay-like compoundObtained by firingComposite metal acid
Metal oxide or rhodium oxide contained in it
From hydrogenated composite metal oxides
Production of synthesis gas by methanol decomposition
A production catalyst (second catalyst) is provided.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the first catalyst of the present invention, magnesium as a first component is present as magnesium oxide, and palladium as a second component is present as palladium oxide or metal palladium. Exists as On the other hand, the third component metal, aluminum, scandium, chromium, iron, gallium or yttrium exists as an oxide or a metal. These third component metals are present in the magnesium oxide lattice, and the palladium is present on the surface or inside the magnesium oxide. In the first catalyst of the present invention, the proportion of palladium is 0.006 to 0.33 atoms, preferably 0.05 to 0.06 atoms, per atom of Mg. The ratio of the third component metal is 0.1 per atom in total of Mg and Pd.
The ratio is 1 to 0.52 atoms, preferably 0.3 to 0.35 atoms.

In order to preferably prepare the first catalyst of the present invention, first, a clay-like compound represented by the following composition formula (2) is prepared.

Embedded image In the above formula, M represents at least one metal selected from Al, Sc, Cr, Fe, Ga and Y. x represents a number smaller than 3, preferably 0.01 to 1.0, more preferably 0.06 to 0.10. m indicates the proportion of water of crystallization, and indicates 0 or more, and the upper limit is usually about 4. To prepare the clay-like compound represented by the composition formula (2), a predetermined amount of an aqueous solution of a nitrate of each catalyst metal is mixed. To this mixture, a separately prepared mixed aqueous solution of sodium carbonate and sodium hydroxide is added. In this mixed aqueous solution, the ratio of the sodium carbonate is 0.5 to 10 mol, preferably 2 to 4 mol, per 1 mol of the third component metal. When mixing the two aqueous solutions, the pH of the mixed solution is adjusted to a range of 8 to 11, preferably 9.9 to 10.1. The mixed solution thus obtained contains a precipitate. Next, this mixed solution was heated to 85 to 95 ° C under stirring to
Aged for about 12 hours. The precipitate obtained is filtered and washed pure and well. The precipitate is dried at 100-200 <0> C. Thus, the clay-like compound represented by the composition formula (2) is obtained. Next, the clay-like compound is heated in air at 400-700 ° C, preferably 425-650.
Calcination is performed at ℃ to obtain a composite metal oxide containing Mg, Pd and a third component metal. The composite metal oxide itself has a large surface area, but can be supported on an inorganic carrier to further increase the contact area with the raw material mixed gas. In this case, examples of the carrier include porous materials such as silica, alumina, titania, magnesia, and zirconia. As a supporting method, a kneading method or an impregnation method which is usually performed can be employed.

[0009] In the second catalyst of the present invention, magnesium as the first component exists as magnesium oxide, and rhodium as the second component exists as rhodium oxide or metal rhodium, but preferably as metal rhodium. On the other hand, the third component metal, aluminum, scandium, chromium, iron, gallium or yttrium exists as an oxide or a metal. These third component metals are present in the lattice of magnesium oxide, and rhodium is present on the surface or inside of the magnesium oxide. In the second catalyst of the present invention, the ratio of rhodium is as follows:
0.003-0.33 atoms, preferably 0.06-0.3.
It is a ratio of 12 atoms. The ratio of the third component metal is 0.11 to 0.52 atoms, preferably 0.1 to 0.5 atoms per Mg atom.
It is a ratio of 2 to 0.4 atoms. The ratio of the total atoms of rhodium and the third component metal is 0.11 to 3 per 3 atoms of Mg.
0.52 atoms, preferably about 1 atom.

In order to preferably prepare the second catalyst of the present invention, first, a clay-like compound represented by the following composition formula (3) is prepared.

Embedded image In the above formula, M represents at least one metal selected from Al, Sc, Cr, Fe, Ga and Y. y represents a number smaller than 1, preferably 0.01 to 0.99, more preferably 0.3 to 0.4. m indicates the proportion of water of crystallization, and indicates 0 or more, and the upper limit is usually about 4. To prepare the clay-like compound represented by the composition formula (3), a predetermined amount of an aqueous solution of a nitrate of each catalyst metal is mixed. To this mixture, a separately prepared mixed aqueous solution of sodium carbonate and sodium hydroxide is added. In this mixed aqueous solution, the ratio of the sodium carbonate is 0.5 to 10 mol, preferably 2 to 4 mol, per 1 mol of the third component metal. When mixing the two aqueous solutions, the pH of the mixed solution is adjusted to a range of 8 to 11, preferably 9.9 to 10.1. The mixed solution thus obtained contains a precipitate. Next, this mixed solution was heated to 85 to 95 ° C under stirring to
Aged for about 12 hours. The precipitate obtained is filtered and washed pure and well. The precipitate is dried at 100-200 <0> C. Thus, the clay-like compound represented by the composition formula (3) is obtained. Next, the clay-like compound is heated in air at 400-700 ° C, preferably 425-650.
Calcination is performed at ℃ to obtain a composite metal oxide containing Mg, Rh and a third component metal. The composite metal oxide itself has a large surface area, but can be supported on an inorganic carrier to further increase the contact area with the raw material mixed gas. In this case, examples of the carrier include porous materials such as silica, alumina, titania, magnesia, and zirconia. As a supporting method, a kneading method or an impregnation method which is usually performed can be employed.

In order to decompose methanol using the catalyst of the present invention, methanol gas is brought into contact with the catalyst. In this case, it is preferable that the palladium (or rhodium) component on the catalyst is previously held in metallic palladium (or rhodium) with hydrogen before the methanol gas is brought into contact with the catalyst. The methanol gas supplied to the reaction may have a concentration of 100%, but may be optionally diluted with an inert gas such as nitrogen. The reaction temperature is 150 to 400C, preferably 175 to 300C. The reaction pressure may be room temperature or pressurized. As a reaction system, any system such as a fixed bed and a fluidized bed can be adopted.

[0012]

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

Example 1 (Preparation of First Catalyst) 0.0426 mol of magnesium nitrate, 0.0024 mol of palladium nitrate and 0.015 mol of nitrate of the third component metal were dissolved in 0.6 liter of water to prepare a catalyst. An aqueous solution A containing a metal as a nitrate was prepared.
Next, an aqueous solution B was prepared by dissolving 1.0 mol of sodium hydroxide in 1 liter of water, and an aqueous solution C was prepared by dissolving 0.9 mol of sodium carbonate in 1 liter of water. Next, 90 ml of aqueous solution B and 50 ml of aqueous solution C
1 was added slowly to obtain a mixed solution D. In this case, an appropriate amount of the aqueous solution B was further dropped as a pH adjuster in order to adjust the pH of the mixed solution D to a range of 10 ± 0.1. This mixed aqueous solution D was heated to 90 ° C.
Stirring was continued for 40 minutes. Next, the mixed aqueous solution D thus obtained contains precipitates.
The mixture was kept at 0 ° C. for 10 hours to mature the precipitate. Next, the precipitate was filtered and thoroughly washed with pure water.
Dry at ℃. The obtained dried product (clay-like compound) was pulverized to an average particle size of about 70 mesh, and the pulverized product was fired in air at 650 ° C. for 14 hours to obtain a composite metal oxide. The metal composition ratio (atomic ratio) of this composite metal oxide is M
g: 2.84, Pd: 0.16, M (third component metal):
1.0.

Example 2 (Preparation of the second catalyst) Instead of the aqueous solution A containing the catalyst metal of Example 1, 0.045 mol of magnesium nitrate, 0.0044 mol of rhodium nitrate and 0.1% of the nitrate of the third component metal were used. A second catalyst was prepared in the same procedure as in Example 1, except that an aqueous solution E in which 010 mol was dissolved in 0.6 liter of water was used. The metal composition ratio (atomic ratio) of the composite metal oxide obtained here was as follows: Mg: 3.00, Rh: 0.33, M
(3rd component metal): 0.66.

Example 3 (Decomposition of methanol) Catalyst 0.3 obtained as described above
g was filled into a U-shaped quartz reaction tube having an inner diameter of 10 mm to form a catalyst tube, which was held in an electric furnace. First, after heating this catalyst tube to 400 ° C., hydrogen gas was passed at a flow rate of 0.01 liter / min for 1 hour. Thereby, the first
Reducing palladium oxide in the catalyst of the above to metal palladium,
Also, rhodium oxide in the second catalyst was reduced to metal rhodium. Next, the catalyst tube was maintained at 200 to 300 ° C. (reaction temperature), and a methanol / nitrogen mixed gas (methanol concentration: 40 vol%) was passed at a rate of 3 liter / hour.
The resulting product gas was analyzed to evaluate the reaction result. First
Table 1 shows the results obtained with the catalyst No. 2, and Table 2 shows the results obtained with the second catalyst.

[0016]

[Table 1]

[0017]

[Table 2]

DME shown in Tables 1 and 2 represents dimethyl ether, and MF represents methyl formate.

[0019]

According to the catalyst of the present invention, methanol can be decomposed into synthesis gas (CO + H ₂ ) at a low reaction temperature and at a high selectivity.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI B01J 23/652 B01J 23/64 103M (72) Inventor Satoshi Hamakawa 1-1-1, Higashi, Tsukuba, Ibaraki Pref. In-house (72) Inventor Katsuomi Takehira 1-1-1 Higashi, Tsukuba, Ibaraki Pref., National Institute of Advanced Industrial Science and Technology (72) Inventor Ryuji Shiozaki 1201 Takada, Kashiwa-shi, Chiba Pref. Author Tomoko Ishii 1201 Takada, Kashiwa City, Chiba Prefecture Inside the Industrial Creation Research Institute (72) Inventor Mikio Kumagai 1201 Takada Kashiwa City, Chiba Prefecture Examiner at the Industry Creation Research Institute Misako Anzai (56) References JP Akira 60-202739 (JP, A) JP-A-60-202740 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C01B 3/22 B01J 23/44 B01J 23/46 3 11 B01J 23/62 B01J 23/63 B01J 23/652

Claims (4)

(57) [Claims] 1. Synthesis gas produced by the decomposition reaction of methanol
In the manufacturing method,The following general formula Mg _6-2x Pd _2x M _Two (OH) ₁₆ CO _Three ・ MH _Two O (Where M is Al, Sc, Cr, Fe, Ga and Y
Represents at least one metal selected from the group consisting of
Indicates a small number, m indicates the percentage of water of crystallization, and 0 or
The above numbers are shown) Represented by Clay-like compoundObtained by firingComposite metal acid
Metal or palladium oxide contained in it
Hydrogenated complex metal oxide hydrogen reduced to indium?
Of syngas using a catalyst consisting of
Law. (2)The following general formula Mg _6-2x Pd _2x M _Two (OH) ₁₆ CO _Three ・ MH _Two O (Where M is Al, Sc, Cr, Fe, Ga and Y
Represents at least one metal selected from the group consisting of
Indicates a small number, m indicates the percentage of water of crystallization, and 0 or
The above numbers are shown) Represented by Clay-like compoundObtained by firingComposite metal acid
Metal or palladium oxide contained in it
Hydrogenated complex metal oxide hydrogen reduced to indium?
Synthesis gas by methanol decomposition characterized by consisting of
Production catalyst. 3. The synthesis gas produced by a methanol decomposition reaction.
In the manufacturing method,The following general formula Mg _Three Rh _y M _1-y (OH) ₁₆ CO _Three ・ MH _Two O (Where M is Al, Sc, Cr, Fe, Ga and Y
At least one metal selected from the group consisting of
Indicates a small number, m indicates the percentage of water of crystallization, and 0 or
The above numbers are shown) Represented by Clay-like compoundObtained by firingComposite metal acid
Metal oxide or rhodium oxide contained in it
Hydrogenated composite metal oxide hydrogen reduced to
Hydrogen conversion of rhodium oxide to rhodium metal
Using a catalyst consisting of a hydrogenated product of a composite metal oxide
A method for producing synthesis gas. 4. A compound represented by the following general formula: Mg ₃ Rh _y M _1-y (OH) ₁₆ CO ₃ .mH ₂ O (where M is Al, Sc, Cr, Fe, Ga and Y
At least one metal selected from the group consisting of
Indicates a small number, m indicates the percentage of water of crystallization, and 0 or
A) a composite metal oxide obtained by calcining a clay-like compound represented by the above number) or a hydrogenated product of a composite metal oxide obtained by reducing rhodium oxide contained therein to rhodium metal by hydrogen. A catalyst for syngas production by methanol decomposition characterized by the following.