JPH0889802A - Catalyst for reforming methanol and its preparation and method for reforming methanol - Google Patents

Abstract

PURPOSE: To provide a highly active catalyst related to a reforming catalyst for producing hydrogen from methanol and to provide a highly efficient method for reforming methanol. CONSTITUTION: A catalyst for reforming methanol consists of an alloy of general formula TM (wherein T is at least one of rare earth elements [La, Ce, Pr, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu], Mg, Ca and Mn and M is at least one of IB group and VIII group elements) or TQM (wherein Q is Y, Zn, Zr or Hf) and the surface is prepd. by dispersing metal fine particles consisting of the element M on an oxide consisting of the element T or a composite or a mixture of the element T and the element Q. In addition, the above described catalyst is prepd. by preparing an alloy contg. an amorphous phase and/or a finely crystalline phase from a melt of TM or TQM and heating it at 50-700 deg.C under an oxidative atmosphere or the same atmosphere as that for reformation of methanol.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a methanol reforming catalyst for producing hydrogen from methanol, a method for producing the same, and a method for reforming methanol.

[0002]

2. Description of the Related Art As an atmospheric gas for semiconductor manufacturing, and as a fuel for fuel cells, which is expected to spread in the future,
The demand for high-purity hydrogen gas is increasing. Therefore, various hydrogen production techniques have been developed, but a method by reforming methanol has been attracting attention as a method for obtaining hydrogen on a small-to-medium scale corresponding to such applications. In recent years, methanol has been established as a technology for mass production from many resources such as petroleum, coal, and natural gas, and it is available at low cost, and it is more dangerous than hydrogen gas from the viewpoint of handling. Because there are few, it is easy to transport and stockpile,
This is because a system that easily produces hydrogen can be realized. The catalyst used for reforming methanol is disclosed in JP-A-49-47281 and JP-B-54-11.
274, JP-A-57-56302, JP-A-58-17836, JP-A-59-131501, JP-A-60-96504, and JP-A-60-7.
7103, JP-A-60-77104, etc. are known. Further, as a catalyst for converting methanol into hydrogen, Japanese Patent Laid-Open No. 166937/1983 is also known. A method for producing methanol using an amorphous alloy as a catalyst is described in JP-A-60-87233.

[0003]

All of the above known Cu-based methanol reforming catalysts have been put to practical use in hydrogen production plants and the like. However, in order to solve energy / environmental problems, demand for hydrogen will continue to increase, and power generation, cogeneration, etc.
When hydrogen is used for various purposes, the performance of the current Cu-based catalyst is insufficient, and high activity at lower temperatures, high selectivity at high temperatures, and durability are desired. Also in terms of catalyst production, the conventional method uses a metal salt or metal oxide as a starting material, and in order to function as a catalyst, it is heated in an air flow containing hydrogen, and metal oxide or metal oxide is used. Since a process of reducing a part of the oxide is indispensable, there are drawbacks that the process is complicated and it is difficult to obtain a large activity. Further, the one described in JP-A-58-166937 also has a problem that the process is long and complicated because it is similarly prepared by a chemical method using a metal salt as a raw material. Therefore, the present invention has a high activity at a relatively low temperature, and in addition to a high activity even at a high temperature, has a high selectivity, and a methanol reforming catalyst which can be produced by a simple non-aqueous process and a method for producing the same. Another object of the present invention is to provide a methanol reforming method that can be efficiently decomposed at a relatively low temperature and that can simplify the process.

[0004]

The first aspect of the present invention is to provide a compound represented by the general formula: TM (where T is a rare earth element [La, Ce, P
r, Nd, Pm, Sm, Eu, Gd, Tb, Dy, H
o, Er, Tm, Yb, Lu] and Mg, Ca, Mn
At least one element selected from M and M is the periodic table IB
Group [Cu, Ag, Au] and Group VIII [Fe, Co, N]
i, Ru, Rh, Pd, Os, Ir, Pt] and at least one element selected from the alloys, the surface of which is an oxide of T element on which fine metal particles of M element are dispersed. The catalyst for reforming methanol is characterized in that In the above general formula, T element is 5 to 95% and M element is 95 to 5% in atomic percent.
Further, the size of the metal fine particles composed of M elements dispersed in an island shape is from sub-nanometer to several tens of nanometers, and more specifically, particles of 30 nm or less work particularly effectively as a catalyst. By combining the T element and the M element represented by the general formula, the rapidly solidified body of the molten alloy is an amorphous alloy or a mixed phase of an amorphous and a fine crystalline phase (including an amorphous phase). Alloy) or an alloy consisting of a fine crystalline phase, and subjecting it to a predetermined heat treatment to disperse the metal fine particles of the M element or the ultrafine metal oxide particles of which the surface layer is a metal on the oxide of the T element. The resulting surface layer can be obtained. The oxide composed of the T element is bound to the metal fine particles composed of the M element through a strong interaction, and the metal fine particles are stably fixed as they are and show a large activity. If the combination of the T element and the M element deviates, the catalytic activity is low even if the amorphous phase is used as a precursor.

The preferred ranges of the T element and the M element are most effective for obtaining an amorphous phase and a fine crystal structure near the eutectic point on the alloy phase diagram, and therefore the catalytic activity is also high. 5 to 95% of T element and 9 of M element in atomic percent
Although it is 5 to 5%, by setting it in this range, a structure in which fine metal particles are dispersed on an oxide showing a large activity is more remarkably exhibited. As a specific example, La _bal Au _{10 to 95 for LaAu} alloy and Ce _bal Co for CeCo alloy.
_{5 to 50} , Nd _bal Ag ₁₀ to 95 for NdAg alloy, GdAu
Gd _bal Au _{5 to 90} for alloys, Mg _{bal for} MgPd alloys
_Pd 5~30, Ca _bal Cu 10~50 a CaCu alloy, Mn
_{Examples of the} Cu alloy include Mn _bal Cu _{40 to 80} . Of course, the range is about the same for other combinations. Further, a part of the T element of the above alloy composition is a Q element (where Q is Y, Z
Substitution with at least one element selected from n, Zr, and Hf), and the composition of TQM (atomic element is 5 to T element 5 to
95%, M element is 95 to 5% of the amount of T element in the amount of more than 1% and less than 95% of the amount of the element is replaced by the Q element), so that the surface thereof when subjected to the oxidation treatment. Is effective in increasing the density of the dispersion, such as fine metal particles of the M element being dispersed at a higher density on the composite oxide of the T element and the Q element or the mixed oxide of the T element and the Q element. Therefore, the replacement with the Q element also improves the activity and life of the catalyst. The preferable composition range of TQM is most effective for obtaining an amorphous phase or a fine liquid crystal structure near the eutectic point on the alloy phase diagram, and a large catalytic activity is obtained.
Incidentally, as a particularly effective element, the T element is La, Ce,
Pr, Nd, Gd, Dy, and M element is Cu, Ag,
Au and the Q element is Zn and Zr. The combination of these elements generally has a greater catalytic activity than the others.

The preferred composition range of each element is T element: 30 to 70%, M element: 30 to 70, Q element:
0 to 30%. A large catalytic activity is obtained within this range. As described above, the size of the metal fine particles is from sub-nanometer to several tens of nanometers, more specifically, 30 nm.
Below, particularly, when the thickness is 10 nm or less, the catalytic effect is dramatically improved. Furthermore, 5 nm or less is preferable. The subject reactions of the catalyst of the present invention include the following two methods: a direct decomposition method (1) for directly decomposing methanol to produce hydrogen, and a steam reforming method (2) for producing hydrogen from methanol and steam. .

[0007]

[Equation 1]

In the second aspect of the present invention, an alloy containing an amorphous phase and / or a fine crystalline phase is prepared from the melt composition of the alloy represented by the above general formula TM or TQM, and this is prepared in an oxidizing atmosphere or methanol. A method for producing a methanol reforming catalyst, which comprises heating to 50 to 700 ° C. in an atmosphere equivalent to quality to deposit and disperse fine metal particles of M element on an oxide of T element on the alloy surface. Is. As a means for producing an alloy containing the above-mentioned amorphous phase and / or fine crystalline phase, 10 ⁴ to 10 ⁶ K /
There are a method of rapidly solidifying at a cooling rate of s, an atomizing method, a submerged spinning method, an MA (mechanical alloying) method, a sputtering method, a plating method and the like. When such an alloy is exposed to an oxidizing atmosphere, a methanol reforming atmosphere, or an atmosphere equivalent thereto, the surface layer is oxidized, and the surface oxide is formed on the oxide composed of the T element or the composite oxide of the T element and Q element or the T element and Q
Fine metal particles of the element M of sub-nanometers to tens of nanometers are dispersed on the mixed oxide of the elements, which shows high catalytic activity. When producing a catalyst in which fine metal particles are dispersed on the above-mentioned oxide, it is necessary to set the heating temperature to 50 to 700 ° C. That is, some of these catalysts have an activity at a low temperature and an activity at a high temperature for the purpose of, for example, binding to a molten carbonate fuel cell, so that 50- Limited to 700 ° C.

The second invention described above is a method for producing a catalyst.
This is because the starting alloy of the general formula: TM or TQM is treated in the same atmosphere as the methanol reforming, so if the starting alloy is placed in the methanol reforming process and the methanol reforming reaction is immediately started, The starting alloy is catalyzed and contributes to the methanol reforming reaction as a catalyst. Therefore, the heating temperature is also preferably 150 to 500 ° C. In this method, the reaction occurs from about 120 ° C. due to the activity of the catalyst, and a high conversion rate from methanol to hydrogen is exhibited in the range of 300 to 500 ° C.

[0010]

EXAMPLES The present invention will be specifically described below based on examples. Example 1 An alloy of Gd ₇₉ Au ₂₁ was made in an arc melting furnace, and this was inserted into a quartz tube having a small hole at the tip. After heating and melting, the quartz tube was placed directly on a roll of 200 mm and the rotation speed was 4
000r. p. m. Under high pressure, the molten metal in the quartz tube was jetted from a small hole in the quartz tube at 0.4 kg / cm ² under Ar pressure and brought into contact with the surface of the roll to rapidly solidify to obtain a thin body with a width of about 1 mm. It was The cooling rate at this time is 1
It is 0 ⁵ K / s. Using this thin body, a catalytic reaction test was conducted using a fixed-bed flow reactor. A thin body filling amount was set to 0.1 g, and a mixture of methanol and water vapor was passed through the thin body layer using nitrogen gas as a carrier to catalyze the thin body and to carry out a methanol reforming reaction. The catalytic activity was determined by analyzing the produced gas components by gas chromatography. The performance is shown in Table 1.

Example 2 Table 1 shows the performance as a catalyst of a thin body produced by the same method as in Example 1 using an alloy composed of Ce ₇₆ Co ₂₄ . Example 3 An alloy made of Nd ₈₀ Au ₂₀ is manufactured by the same method as in Example 1 and the performance as a catalyst of a thin body is shown in Table 1.

Comparative Example CuO— prepared by a chemical method using a metal salt as a starting material.
The performance of the ZnO catalyst is shown in Table 1. As shown above, Examples 1 to 10 of the present invention are superior in activity and selectivity as compared with Comparative Examples, and also have sufficient reproducibility by repeated use, durability and the like. Table 2 shows the volume of hydrogen that can be generated in 1 minute per 1 kg of the catalyst in the standard state together with other examples including the above-mentioned Examples and Comparative Examples. An example showing the selectivity of the catalyst at high temperature is shown in FIG.

[0013]

[Table 1]

[0014]

[Table 2]

[0015]

The methanol reforming catalyst according to the present invention is
It exhibits a large catalytic activity at a relatively low temperature, a high hydrogen generation amount at 300 ° C. or higher, and exhibits good activity and selectivity even at a high temperature of 350 ° C. or higher. In addition, the production method can obtain the catalytic activity by a simple process.
Furthermore, according to the methanol reforming method of the present invention, methanol can be efficiently reformed to obtain hydrogen from a low temperature to a high temperature, and the catalyst itself can be activated prior to the reforming process. Can be simplified.

[Brief description of drawings]

FIG. 1 is a diagram showing the selectivity of a catalyst at each temperature.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Ken Masumoto 3-8-22, Uesugi, Aoba-ku, Sendai-shi, Miyagi Prefecture (72) Akihisa Inoue Kawauchi Muzenchi, Kawauchi 11-806, Aoba-ku, Sendai-shi, Miyagi Prefecture

Claims (16)

[Claims] 1. A general formula: TM (where T is a rare earth element [La, Ce, Pr, Nd, Pm, Sm, Eu, Gd,
Tb, Dy, Ho, Er, Tm, Yb, Lu] or M
at least one element selected from g, Ca and Mn, M
Is a group IB [Cu, Ag, Au] and a group VIII [Fe, Co, Ni, Ru, Rh, Pd, Os, Ir,
Pt] at least one element selected from the above) and the surface of which is an oxide of T element and M
A catalyst for reforming methanol, characterized in that fine metal particles comprising an element are dispersed. 2. The atomic percentage of T element is 5 to 95.
%, M element is 95-5%, The catalyst for reforming methanol according to claim 1. 3. The general formula: TQM represented by the general formula: TM, in which a part of the T element of the alloy according to claim 1 is replaced by the Q element.
(However, Q is an alloy represented by at least one element selected from Y, Zn, Zr, and Hf), and its surface is on a composite oxide of T element and Q element or a mixed oxide of T element and Q element. A catalyst for reforming methanol, which is characterized in that fine metal particles of M element are dispersed therein. 4. The atomic percentage of T element is 5 to 95%,
The methanol reforming catalyst according to claim 3, wherein the M element is obtained by substituting the Q element in an amount of more than 1% and less than 95% of the T element in 5 to 95%. 5. The size of the metal fine particles of M element is from sub-nanometer to several tens of nanometers.
Or the catalyst for reforming methanol according to 3. 6. The general formula: TM (where T is a rare earth element [La, Ce, Pr, Nd, Pm, Sm, Eu, Gd,
Tb, Dy, Ho, Er, Tm, Yb, Lu] or M
at least one element selected from g, Ca and Mn, M
Is a group IB [Cu, Ag, Au] and a group VIII [Fe, Co, Ni, Ru, Rh, Pd, Os, Ir,
An alloy containing an amorphous phase and / or a fine crystalline phase is prepared from a molten composition of at least one element selected from Pt], and the alloy is prepared in an oxidizing atmosphere or an atmosphere equivalent to methanol reforming at 50 to 700 ° C. A method for producing a methanol reforming catalyst, characterized in that fine particles of metal consisting of M element are deposited and dispersed on an oxide consisting of T element on the surface of the alloy by heating. 7. The atomic percentage of T element is 5 to 95%,
The method for producing a methanol reforming catalyst according to claim 6, wherein an alloy in which the M element is 95 to 5% is used. 8. A general formula: TQM in which a part of the T element of the alloy according to claim 6 represented by the general formula: TM is replaced with a Q element.
(However, Q is at least one element selected from Y, Zn, Zr, and Hf) An alloy containing an amorphous and / or fine crystalline phase is prepared from a molten composition, and this is subjected to an oxidizing atmosphere or methanol reforming. By heating to 50 to 700 ° C. in an equivalent atmosphere, fine metal particles of M element are precipitated and dispersed on the composite oxide of T element and Q element or the mixed oxide of T element and Q element on the alloy surface. A method for producing a methanol reforming catalyst, comprising: 9. The atomic percentage of T element is 5 to 95%,
The method for producing a catalyst for reforming methanol according to claim 8, wherein the element M is an alloy obtained by substituting the element Q in an amount of more than 1% and less than 95% of the element T in 5 to 95%. 10. The method for producing a methanol reforming catalyst according to claim 6, wherein the size of the fine particles of the metal containing the M element is from sub-nanometer to several tens of nanometers. 11. A general formula: TM (where T is a rare earth element [La, Ce, Pr, Nd, Pm, Sm, Eu, G
d, Tb, Dy, Ho, Er, Tm, Yb, Lu] or at least one element selected from Mg, Ca, Mn, M is IB group [Cu, Ag, Au] and VI of the periodic table.
Group II [Fe, Co, Ni, Ru, Rh, Pd, Os, I
At least one element selected from r, Pt] is introduced into a rapidly solidified alloy of methanol or methanol and steam, and the mixture is heated to 100 to 700 ° C., and a method for reforming methanol is characterized. 12. The atomic percentage of T element is 5 to 95.
%, M element is 95 to 5%, and an alloy is used.
The method for reforming methanol described. 13. The method for reforming methanol according to claim 11, wherein the surface of the rapidly solidified alloy is formed by dispersing fine metal particles of M element on an oxide of T element. 14. A general formula: T in which a part of the T element of the alloy according to claim 11 represented by the general formula: TM is replaced by a Q element.
QM (where Q is at least one element selected from Y, Zn, Zr, and Hf) is used to introduce methanol or methanol and steam into the rapidly solidified alloy,
A method for reforming methanol, which comprises heating to 0 ° C. 15. A T element in an atomic percentage of 5 to 95%,
The method for reforming methanol according to claim 14, wherein an alloy obtained by substituting an amount of more than 1% and less than 95% of the T element in the M element of 5 to 95% by the Q element is used. 16. The surface of a rapidly solidified alloy is obtained by depositing and dispersing fine metal particles of M element on a complex oxide of T element and Q element or a mixed oxide of T element and Q element. The method for reforming methanol according to claim 14.