JP3099976B2 - Carbon-based shape-selective catalyst and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbonaceous catalyst having excellent heat resistance and chemical resistance and a method for producing the same. More specifically, the present invention relates to a shape-selective carbonaceous catalyst in which coal, pitch and other modifiers and a phenol resin are used as raw materials, and in which the pore size and pore size distribution are accurately controlled, and a method for producing the same.

[0002]

2. Description of the Related Art Generally, carbon materials have excellent properties not found in other industrial materials, that is, low specific gravity, heat resistance, chemical resistance, thermal shock resistance, electric and thermal conductivity, high-temperature strength, and the like.
It has lubricity and biocompatibility.

[0003] For this reason, they have been widely used as high-temperature structural materials such as electrodes, refractories, carbon brushes, mechanical seals, and bearings, and special mechanical parts since ancient times. Recent advances in chemical technology have led to the development of carbon materials with new functions, such as high-density graphite for electronic furnaces, high-performance carbon fibers, and biocarbon for living organisms.

On the other hand, as carbon materials, coal,
Petroleum and its derivatives are mainly used, but there is a pressing need to review the current state of dependence on petroleum, including energy. Coal is mainly made of coke and fuel, but it is an energy source that replaces oil,
There is a need for a utilization technology that provides a wide range of added value, including the development of liquefaction, gasification, etc. as a chemical raw material source.

Japanese Patent Application Laid-Open No. Hei 3-40912 discloses a molecular sieve carbon in which a carbonaceous mesophase fine powder or a compact obtained by adding a binder thereto and granulating is carbonized in a non-oxidizing atmosphere in a temperature range of 500 to 1100 ° C. Manufacturing methods have been proposed. This is for coal tar pitch and petroleum heavy oil.
A mesophase produced by heating at a temperature of about 50 ° C. to 500 ° C. is used. The purpose is to produce molecular sieve carbon used for mixed gas separation.

[0006] Catalysts are the most important functional materials for the chemical industry. In order to exert this function, it is necessary to appropriately control the pore structure. The importance of the pore structure is based on the following reasons. Since the catalysis of a solid is a surface phenomenon, its activity is primarily proportional to the surface area. In order to increase the surface area and smoothly operate the reactor, a porous structure is essential. In the case of a noble metal-supported catalyst, when the loading rate per surface area is increased, aggregation of the metal is likely to occur, and the stability is reduced. When the pore diameter is about the same as the reacting molecule, the reacting molecule can be identified by its shape and size, and only a specific reaction can be caused.

Zeolite is known as a representative catalyst having a molecular shape selectivity by controlling the pore diameter. However, in terms of heat resistance, chemical resistance, etc., it has the same characteristics as a carbon material as a raw material. A catalyst having the same has been demanded from various fields.

Conventionally, carbon having molecular shape selectivity is
Basically, it is manufactured by a method shown below or a combination thereof. Pyrolysis method A method in which Saran and vinylidene chloride are pyrolyzed under controlled conditions. Coating method Activated carbon and various carbides are thermally decomposed by adding pitch and resin.
A method of controlling pores with pyrolytic carbon. (For example, JP
JP-A-10-69882, JP-A-59-45914, etc.)

Activation Method A method of appropriately activating carbides under strict conditions to enlarge pores. (For example, JP-A-53-1195, etc.) Evaporation method Activated carbon or the like is treated with a gas containing benzene, toluene, or the like at a temperature of 600 to 900 ° C., and pyrolytic carbon is evaporated on the pore walls to reduce the pores. how to. (For example, Japanese Patent Publication No. 56-13
No. 0226)

In each of these methods, basic pores are generated in advance by thermal decomposition of a carbon material or the like, and then the diameter of the pores is finely adjusted to meet the purpose. In these methods, since the formation of basic pores is dominant, the selection of a raw material is important, and it has been very difficult to obtain an appropriate raw material from many raw materials. In addition, since only a limited combination of raw materials can be used, it was not possible to control the pore diameter according to needs, and the pore distribution could not be sharpened.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to provide a carbon material-based catalyst having a shape selectivity capable of freely controlling the pore diameter and its distribution from the same raw material according to the purpose of each reaction, and a catalyst for the same. An object of the present invention is to provide a production method and a method for selectively decomposing methanol into only CO and H ₂ using the catalyst.

[0012]

Means for Solving the Problems The present inventors have intensively studied to solve the above-mentioned problems. As a result, by mixing a modifier such as coal and pitch and a phenolic resin, and adjusting the blending amount of the pitch, the amount of the phenolic resin, and the carbonization conditions, carbonization is performed, and the shape selectivity in which the pore system is precisely controlled is controlled. It has been found that a carbon material-based catalyst having the following formula is obtained, and the present invention has been completed.

That is, the present invention provides (1) a pore diameter of 0.3 to 0.6 obtained by mixing and carbonizing coal and phenol resin as raw materials.
nm, the ratio of the pore diameter having a width of 0.04 ± 0.02 nm to the average pore diameter has a pore volume distribution of 70% or more,
A carbon-based shape-selective catalyst having a pore volume of 0.1 to 0.2 cc / g. (2) Coal, phenolic resin, and five kinds of modification of pitch, anthracene, dihydroanthracene, acenaphthylene, and polyvinyl alcohol Pore diameter of 0.3 to 0.6 nm obtained by mixing and carbonizing at least one type of modifier selected from the group of materials as a raw material, and 0.3 to 0.6 nm with respect to the average pore diameter.
The ratio of the pore diameter having a width of 04 ± 0.02 nm is 70% or more, and the pore volume is 0.1 to 0.2 cc.
/ g is a carbon-based shape-selective catalyst, and (3) either a mixing method in which a raw material is preliminarily mixed with metal fine powder or a metal salt compound to produce a catalyst, or an impregnation method in which the produced catalyst is impregnated with a metal salt compound. The carbon-based shape-selective catalyst according to the above 1 or 2, wherein the metal is supported by the method described above. (4) 20 to 70 parts by weight of finely pulverized coal having an average particle diameter of 10 μm or less; (5) The method for producing a carbon-based shape-selective catalyst according to the above (1), wherein the solidified product is pulverized to 10 × 30 mesh and carbonized. 20-70 parts by weight of pulverized coal, softening point 60-100 ℃,
5-35% by weight of toluene-insoluble matter, 0 of quinoline-insoluble matter
10 to 10% by weight of a pitch or other modifier is mixed with 0 to 40 parts by weight, and the mixture is solidified with 20 to 40 parts by weight of a phenol resin. 3. The method for producing a carbon-based shape-selective catalyst according to the above item 2, wherein (6) the heating rate is 2 to 20 ° C./min in an inert atmosphere,
The carbonaceous shape selection according to the above item 4 or 5, wherein carbonization is carried out in a temperature range of 0 ° C., and the average pore diameter and the pore diameter distribution are controlled by controlling the temperature rising rate and the carbonization temperature within the range. (7) adjusting the addition amount of the modifier within the range of 0 to 40 parts by weight and adjusting the addition amount of the phenol resin within the range of 20 to 40 parts by weight to obtain the average pore diameter and A method for producing a carbon-based shape-selective catalyst according to the above item 5, wherein the pore size distribution is controlled,
(8) The pore diameter is 0.4 to 0.45 nm, and 0.5 nm
CO, characterized by using the carbon-based shape-selective catalyst according to claim 3 or 6, which hardly contains the above pores.
This is a methanol decomposition method for selectively obtaining only H ₂ .

The mixing ratio of the raw materials is adjusted in the range of 0 to 40 parts by weight of the pitch or other modifier and 20 to 40 parts by weight of the phenol resin with respect to 20 to 70 parts by weight of coal. By changing the ratio, the pore size and its distribution can be controlled. By changing the addition ratio of the pitch or other modifier, the pore diameter can be accurately controlled without changing the pore volume and distribution. That is, the pore diameter can be reduced by increasing the addition rate of the pitch and the like. Since the phenol resin is non-graphitizable carbon, the addition of the phenol resin prevents heat shrinkage and increases the pore diameter and pore volume. In the present invention, the ratio of the pore diameter having a width of 0.04 ± 0.02 nm to the average pore diameter having a pore volume distribution of 70% or more means that, for example, when the average pore diameter is 0.4 nm, 0% .34
It means that the ratio of the pore volume in the range of nm to 0.46 nm or 0.38 nm to 0.42 nm accounts for 70% or more of the total pore volume.

As the modifier, coal tar pitch is usually preferably used, but has a softening point of 60 to 100 ° C., a toluene insoluble content of 5 to 35% by weight, and a quinoline insoluble content of 0 to 10%.
% By weight, preferably 70-90 ° C. softening point, 10-15% by weight of toluene-insoluble matter, 1-3% by weight of quinoline-insoluble matter
Is preferable. Pitches having a softening point of less than 60 ° C. have problems such as low carbonization yield and foaming during carbonization, and pitches having a softening point of more than 100 ° C. increase the temperature conditions when mixing with coal and phenolic resins. There is a problem. When the medium pitch is used as a modifier, solidification with a phenol resin is usually performed by mixing phenol and formaldehyde at a ratio of 1: 1 and adding a small amount of aqueous ammonia as a catalyst and leaving the mixture at 95 ° C. for 5 hours.

After the phenol resin is added and solidified, the solidified product is pulverized into a 10 × 30 mesh and carbonized. The carbonization method is such that the temperature rise rate and the carbonization temperature are set accurately under an inert atmosphere. Any device can be used as long as it can be used, but it is desirable to use a fluidized bed reactor or the like capable of uniformly reacting the pulverized particles. In the present invention, an expression such as 10 × 30 mesh means that a 10-mesh sieve passes and remains on a 30-mesh sieve.

The heating rate is adjusted within the range of 2 to 20 ° C./min, preferably around 10 ° C./min.
If it exceeds min, foaming or the like, and it is difficult to control the pore diameter, and if it is less than 2 ° C./min, it takes too much time for carbonization.
The carbonization temperature is adjusted in the range of 600 to 1,000 ° C,
If the temperature is lower than 600 ° C., the pores do not develop sufficiently,
If the temperature exceeds 0 ° C., both the pore diameter and the pore area decrease, and the desired catalyst cannot be obtained. 600-1,000 ° C
In the range, the pore diameter decreases with an increase in the carbonization temperature, and the pore area does not change.

The retention time after reaching a predetermined carbonization temperature also affects the pore volume distribution. At high temperatures, both the pore volume and pore diameter decrease as the retention time increases.

When used as a catalyst carrier, Ni, C
o, Mo, Fe, a mixing method of mixing a metal catalyst of a water-soluble metal salt compound such as metal fine powder such as Fe, Cu or a metal nitrate with the raw material coal, pitch, etc. from the beginning, and then carbonizing the obtained metal. It is also possible to use an impregnation method in which a metal salt compound is impregnated. In the case of supporting Ni, in the mixing method, the metal nitrate may be dissolved and mixed in formaldehyde, which is a crosslinking agent for the phenolic resin, and in the impregnation method, the vacuum degassed carbide may be immersed in an aqueous metal nitrate solution having a predetermined concentration. .

By combining the mixing ratio of the raw materials and the conditions of the carbonization temperature, it is possible to finely control the pore diameter of the obtained carbonaceous catalyst while keeping the distribution sharp. It is conventionally known that the activation time can be controlled by the activation time of the activated carbon, the temperature, the partial pressure of steam, etc., and that the pore diameter can be increased.However, in this case, it is difficult to keep the distribution sharp. In addition, the pore distribution becomes broad. From this point, it is apparent that the present invention is excellent in that the pore diameter can be reduced or increased while maintaining the sharpness of the distribution of the pore diameter.

In an example of application to the decomposition reaction of methanol using the carbonaceous catalyst of the present invention in which the pore diameter is precisely controlled to 0.4 to 0.45 nm, the product is CO,
There is only H ₂ , and CH ₄ , H ₂ O, and CO ₂ are not generated because the molecular size of the reaction intermediate is larger than the pore diameter.
This is an epoch-making example in which a catalyst having shape selectivity has been extremely effective in controlling a chemical reaction.

[0022]

EXAMPLES The present invention will be described more specifically with reference to the following examples, but the present invention is not limited to these examples. (Example 1) Preparation of catalyst Coal, (abbreviated as Baidley coal, BC) is finely pulverized to 10 µm or less and solidified with a phenol resin (abbreviated as PF). If a modifier is used, one (1) coal (BC)
Finely pulverized to a size of 0 μm or less, and coal tar pitch (P
) Or polyvinyl alcohol (abbreviated as PVA) and then solidified with a phenolic resin (PF). The solidified product was pulverized to a particle size of about 1 mm, heated to a carbonization temperature in a nitrogen atmosphere at a rate of 10 ° C./min in a fluidized bed reactor, and held for 15 minutes. The coal tar pitch used had a softening point of 80 ° C., a toluene insoluble content of 13.3% by weight, and a quinoline insoluble content of 2.5% by weight.

The metal catalyst is supported by two methods, namely, a mixing method in which the metal nitrate is mixed and supported on coal or pitch as a raw material of the carbonaceous catalyst, and an impregnation method in which the produced carbonaceous catalyst is impregnated with an aqueous metal nitrate solution. went. In addition, the carbonaceous catalyst produced by the method of the present invention is heated in steam to activate it, and then the metal catalyst impregnated and supported is referred to as an activation method. The weight loss during the carbonization process was measured using a thermobalance at a heating rate of 10 ° C / min.
It was measured in a temperature range of １，1,000 ° C. The pore volume distribution and average pore diameter of each catalyst were determined by the Molecular Probe method and the nitrogen adsorption method. The gas diffusion coefficient was determined by measuring the time-dependent change in pressure at 25 ° C. using a constant-volume adsorption apparatus, and analyzing this by the method of Dryden et al. The results are shown in FIGS.

FIG. 1 shows a pore distribution of a catalyst obtained by carbonizing BC-PF at 600 to 1000 ° C., and FIG.
The pore distribution of the catalyst obtained by carbonizing PF-PVA in the same temperature range was shown. It can be seen that the pore distribution is clearly changed by adding PVA. In the figure,
The pore volume of 5.0 × 10 ^-1 nm and the like is based on Dubinin-Astakhov
By applying the equation, the ultimate adsorption volume of each gas is obtained, and this ultimate adsorption volume is an integrated value obtained assuming that the ultimate adsorption volume corresponds to a volume larger than the molecular diameter. The same applies to FIG.

FIG. 2 shows that the pore diameter can be controlled by changing the carbonization temperature and the mixture ratio (pitch weight%) of the raw material (modifier coal tar pitch).

FIG. 3 shows a weight loss curve and a weight reduction rate in the carbonization process of the BC-PF-PVA-based catalyst. The solid line in the figure is an experimental value, and the broken line is a value calculated assuming that BC, PF, and PVA are carbonized independently. The calculated value and the experimental value are largely different in the initial stage of carbonization (200-500 ° C.), but this tendency was also observed when phenol resin was added with an organic modifier such as anthracene, dihydroanthracene, acenaphthylene, or coal tar pitch. . This is due to the interaction between coal, phenolic resin and organic modifier, and as a result, the pore structure of the carbide of the modified sample can be expected to be different from that of the single carbide of BC and PF. .

FIG. 5 shows that the metal loading on the carbonaceous catalyst has a sharp pore distribution in both the mixing method and the impregnation method, and there is almost no micropores of 0.5 nm or more. On the other hand, the one impregnated and supported after activation has a broad pore distribution, and there are considerable micropores of 0.5 nm or more. FIG. 5 shows a case where Ni is used as the metal,
Tables 1 and 2 show the physical properties of the catalyst when Co, Fe, and Cu are supported as other metal catalysts.

[0028]

[Table 1]

[0029]

[Table 2]

Example 2 Methanol Decomposition Reaction Coal (BC) was pulverized to 10 μm or less, mixed with coal tar pitch, and then solidified with a phenol resin. This is pulverized to a particle size of about 1 mm, and heated at a rate of 1 in a fluidized bed reactor.
Carbonized at 0 ° C / min. And molecular sieve carbon (Molecular Siev
ing Carbon, MSC) catalyst. For the supported metal, select nickel that is highly active in the methanation reaction,
It was supported by two methods, namely, a mixing method in which the raw material of SC (coal, pitch) was mixed and supported, and an impregnation method in which the manufactured MSC was impregnated with an aqueous nickel nitrate solution. Using this carbonaceous catalyst, methanol was decomposed under the following reaction conditions.

The results are shown in FIGS.

[Table 3] Here, W indicates the weight of the catalyst (g-cat), and F indicates the amount charged (mol / h).

The decomposition reaction of methanol proceeds according to the following reaction. Reaction progress (1) CH ₃ OH → CO + 2H ₂ ; ξ ₁ (2) CO + 3H ₂ → CH ₄ + H ₂ O; ξ ₂ (3) CO + H ₂ → (CH ₄ + CO ₂ ) / 2; ξ ₃ (1) Methanol with a large molecular diameter decomposes into hydrogen and carbon monoxide with small molecular diameters. (2) and (3) produce methane with large molecular diameter from hydrogen and carbon monoxide with small molecular diameters. The molecular size of the intermediate is likely to be much larger than that of methanol or methane.

[Table 4]

FIG. 6 shows the relationship between the reaction characteristics and the average pore diameter. F _AO is ₁ xi] methanol flow rate of the reaction inlet is equivalent to methanol conversion. From the figure, the average pore diameter is 0.4 nm
After that, the reaction proceeds rapidly, and the conversion of methanol increases according to the pore diameter, but the reactions of ξ ₂ and ξ ₃ hardly proceed. FIG. 7 shows the relationship between the reaction characteristics and the diffusion coefficient of methanol. It is clear that the conversion rate of methanol increases as the diffusion coefficient increases, but the conversion rate to methane hardly progresses with the catalyst of the present invention as compared with activated carbon and activated products, and it shows shape selectivity.

[0034]

In the present invention, coal and phenolic resin, coal and phenolic resin and pitch and other modifiers are used as raw materials, and the mixing ratio of the raw materials and the carbonization conditions are adjusted to obtain a 0.3 to 0.6 nm. Within this range, it is possible to obtain a carbon-based catalyst or catalyst carrier having substantially uniform pores having a sharp pore diameter distribution. This catalyst can be used for controlling various chemical reactions by utilizing its shape selectivity in combination with the heat resistance and chemical resistance of a carbon-based catalyst, and is expected to be greatly expanded in the chemical industry in the future.

[Brief description of the drawings]

FIG. 1 shows a pore volume distribution of a coal-phenol resin and a carbon-based catalyst.

FIG. 2 shows the relationship between the average pore diameter, the carbonization temperature, and the raw material mixing ratio.

FIG. 3 shows a weight loss curve and a weight reduction rate during carbonization of coal-phenol resin-polyvinyl alcohol and a carbon-based catalyst.

FIG. 4 shows the pore volume distribution of coal-phenol resin-polyvinyl alcohol, and carbon-based catalyst.

FIG. 5 shows the difference in pore volume distribution between the metal loading method and the activation method.

FIG. 6 shows the relationship between the degree of progress of each reaction accompanying the decomposition of methanol and the average pore size of the catalyst.

FIG. 7 shows the relationship between the degree of progress of each reaction accompanying methanol decomposition and the diffusion coefficient of methanol in the pores.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification code FI C01B 3/22 C01B 3/22 A 31/02 101 31/02 101Z 31/08 31/08 A 37/00 37/00 (72 ) Inventor Kazuhiro Mae, Goji Shokan, Uji-shi, Kyoto (No address) Kyoto University staff dormitory 626 (72) Inventor Junichi Hayashi 1-3-19 Tenjincho, Suma-ku, Kobe-shi, Hyogo (72) Inventor Tatsuo Kawaguchi 1-172 Ikutsu Gekyumae, Hozumi-cho, Motosu-gun, Gifu Prefecture (72) Inventor: Miwa Shigeru 4-4-6 Nakai, Kokurakita-ku, Kitakyushu-shi, Fukuoka Examiner Misako Anzai (56) References JP-A-59-230638 (JP A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B01J 21/18 B01J 29/03 B01J 35/10 301 C01B 31/02 101 C01B 31/08 C01B 37/00 CA (STN)

Claims (8)

(57) [Claims] 1. A mixture of carbon and phenolic resin as raw materials, which has a pore diameter of 0.3 to 0.6 nm, wherein a ratio of a pore diameter having a width of 0.04 ± 0.02 nm to an average pore diameter is 70%.
% Or more, and the pore volume is 0.1 to 0.1%.
2 cc / g carbon-based shape-selective catalyst. 2. Coal, phenolic resin and pitch,
Pore diameter of 0.3 to 0.6 nm obtained by mixing and carbonizing at least one modifier selected from five modifier groups of anthracene, dihydroanthracene, acenaphthylene, and polyvinyl alcohol as a raw material. .04 ±
A carbon-based shape-selective catalyst having a pore volume distribution in which a ratio of a pore diameter having a width of 0.02 nm occupies 70% or more and a pore volume of 0.1 to 0.2 cc / g. 3. The method according to claim 1, wherein a metal is supported by a mixing method of preparing a catalyst by previously mixing a metal fine powder or a metal salt compound with the raw material, or an impregnation method of impregnating the prepared catalyst with a metal salt compound. Or a carbon-based shape-selective catalyst according to 2. 4. A method of solidifying 20 to 70 parts by weight of coal finely pulverized to an average particle diameter of 10 μm or less with 20 to 40 parts by weight of a phenol resin, pulverizing the solidified product to 10 × 30 mesh, and then carbonizing. The method for producing a carbon-based shape-selective catalyst according to claim 1. 5. 20 to 70 parts by weight of coal pulverized to an average particle diameter of 10 μm or less, a softening point of 60 to 100 ° C., a toluene insoluble content of 5 to 35% by weight, and a quinoline insoluble content of 0 to 10%.
0 to 40 parts by weight of a pitch or other modifying agent indicating a weight%, and solidified with 20 to 40 parts by weight of a phenol resin. The solidified product was further pulverized to 10 × 30 mesh,
The method for producing a carbon-based shape-selective catalyst according to claim 2, wherein carbonization is performed. 6. A heating rate of 2 to 20 ° C. in an inert atmosphere.
And carbonization in a temperature range of 600 to 1,000 ° C., and controlling the temperature increase rate and the carbonization temperature within the range to control the average pore diameter and the pore diameter distribution. 6. The method for producing a carbon-based shape-selective catalyst according to 4 or 5. 7. The average pore size and pore size distribution are controlled by adjusting the amount of modifier added within the range of 0 to 40 parts by weight and the amount of phenol resin within the range of 20 to 40 parts by weight. The method for producing a carbon-based shape-selective catalyst according to claim 5, characterized in that: 8. A fine particle having a pore diameter of 0.4 to 0.45 nm,
Claim 3 or 6 CO, characterized in that using a carbon-based shape-selective catalyst according, H ₂ only selectively obtain methanolysis process hardly contains pores of more than 0.5 nm.