JPH03141111A - Production of molecular sieve carbon - Google Patents

Abstract

PURPOSE:To improve separation performance by burning microspherical thermosetting resin powder having the surface coated with water-insoluble inorganic salts and a specific value or below of particle diameter or granular formed body prepared by granulating the resin powder at a specified temperature in a nonoxidizing atmosphere. CONSTITUTION:Microspherical thermosetting resin powder having part or all of the surface coated with substantially water-insoluble inorganic salts and <=500mum particle diameter is prepared. The resultant powder, as necessary, is granulated with a binder in an amount of <=60wt.% based on the resin powder to provide a granular formed body. The prepared resin powder or the obtained granular formed body is then burned at a temperature within the range of 500-1100 deg.C in a nonoxidizing atmosphere, Phenols and melamines are used as the thermosetting resin employed therein. Novolak resins, epoxy resins, etc., as necessary, are also used. A polymer binder such as a solution of a liquid phenolic resin or a melamine resin or coal tar, pitch, etc., can be used as the binder.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is a method for producing molecular sieve carbon. Concerning carbon production methods.

[Conventional technology]

Traditionally, silica and silica have been used as adsorbents with molecular sieving effects.
Alumina-based zeolites are widely used and play an important role in gas separation and WI production. however,
The zeolite-based molecular sieve is polar and hydrophilic,
It has the drawbacks of poor heat resistance and chemical resistance, strong selective adsorption to polar substances such as water (and no molecular sieving effect in the presence of polar substances).

Recently, however, it has become possible to produce molecular sieves made from carbon, which is nonpolar and hydrophobic.

This type of molecular sieve carbon has excellent heat resistance and chemical resistance, and is attracting attention as a molecular sieve that can be used even in the presence of polar substances. However, the industrial production of molecular sieve carbon requires complicated steps to control the micropores on the carbon surface, and only complicated and inefficient production methods are used. The performance of this carbon molecular sieve is insufficient for use in the separation of nitrogen and acid residues, and further improvements in separation performance are desired.

[Problem to be solved by the invention]

As a result of extensive research in order to solve the above-mentioned problem, the present inventors found a method to solve the above-mentioned problem and completed the present invention.

An object of the present invention is to provide a new and simple method for producing molecular weight carbon with excellent separation performance.

[Means to solve the problem]

The main purpose is that part or all of the surface is covered with substantially water-insoluble inorganic salts and the particle size is 500 μm.
The following is ゛ Microspherical thermosetting resin particles are placed on the table, and the thermosetting resin particle powder is granulated with a binder of 60% by weight or less to produce a granular molded body. This is achieved by firing the resin particle powder in a non-oxidizing atmosphere at a temperature range of 500 to 1100°C.

The method for producing the microspherical thermosetting resin used in the present invention is as follows.

First, thermosetting l! in an aqueous medium! When reacting fat and aldehydes in the presence of a basic catalyst, the reaction mixture is made to coexist with a salt-free emulsion stabilizer that is substantially insoluble in water.

The thermosetting resins used here are phenols and melamines. Further, novolac resin, epoxy resin, nitrogen-containing compound, etc. may be added as necessary. Phenols include phenol and phenol derivatives, and examples of the phenol derivatives include m-alkylphenol substituted with II with an alkyl group having 1 to B carbon atoms, O-
Alkylphenol, p-alkylphenol, specifically m-cresol, p-ter-butylphenol.

Examples include 0-propylphenol, resorcinol, bisphenol, and halogenated phenol derivatives in which part or all of the hydrogen atoms of their benzene nuclei or alkyl groups are substituted with a base or bromine, and one or more of these is used. Note that the phenols are not limited to these, and any other compound containing a phenolic hydroxyl group can be used. Examples of the aldehydes used here include formaldehyde in the form of formalin or paraformaldehyde, and furfural, and the molar ratio of the aldehyde to the phenol is 1 to 2, preferably 1.1 to 1.4. be. The novolac resin used here is obtained by polymerizing phenols and aldehydes in an acidic catalyst, then neutralizing it with an aqueous solution of caustic soda, dehydrating it under reduced pressure, and having a melting point of 90%.
Those with a low melting point of ℃ or less are preferable.

A part of the melamines used here can be replaced with melamine analogues such as guanidine cyanomelamine, benzoguanamine, etc., or a mixture of two or more of these can be used.

Further, preferable nitrogen-containing compounds used here include aromatic amine compounds and amide compounds having at least one active hydrogen bonded to a nitrogen atom.

Thioamide compounds, urea, 1,000 urea, melamine.

Guanidine, guanamine, dicyandiamide, cyanuric acid and the like are preferred, and the preferred amount used is 2 to 200% by weight, preferably 5 to 100% by weight, more preferably 5 to 50% by weight, based on the phenol.

The epoxy W fat used here has a 4%
The preferred amount used is 0 to 200% by weight.

In addition, as the basic catalyst used here, basic catalysts used in ordinary resol resin production can be used, such as aqueous ammonia, hexamethylenetetramine, and alkyl base catalysts such as dimethylamine, diethyltriamine, and polyethyleneimine. It will be done. The molar ratio of these basic catalysts to the phenols is preferably 0.02 to 0.2.

The emulsion stabilizer used herein is a substantially water-insoluble inorganic salt having a solubility in water of 0.2 f/l or less at 26°C, or an organic protective colloid. For example, calcium fluoride.

Magnesium fluoride, strontium fluoride, calcium phosphate, magnesium phosphate, barium phosphate, aluminum phosphate, barium sulfate, calcium f7M acid,
Zinc hydroxide, aluminum hydroxide.

Examples include iron hydroxide, especially calcium fluoride.

Magnesium fluoride and strontium fluoride are preferred.

This reaction is carried out in an aqueous medium, and the amount of water charged in this case is, for example, when the solid content concentration of the resin is 30 to 70 weight tons.
% is desirable. Stirring of each raw material in the aqueous medium is carried out at a heating rate of 0.5 to 1.5°C/+min.

A stable aqueous emulsion can be obtained by gradually increasing the temperature, preferably at a rate of 0.8 to 1.2°C/min, reacting for 60 to 150 ml at a reaction temperature of 70 to 90°C, and then cooling to 40'C or less.

Next, this aqueous emulsion is separated into solid and liquid by filtration or centrifugation, washed and dried to form solid microspherical heat-cured particles with a particle size of 500 cm or less and whose surfaces are coated with substantially insoluble inorganic salts. A synthetic resin powder is obtained.

Examples of the binder used for molding microspherical thermosetting resin particles into a granular molded body include liquid phenol resin, bath solution of thermosetting resin such as melamine resin, polyvinyl alcohol, or water-soluble or water-swellable cellulose. A polymer binder such as a derivative, coal tar, pitch, etc. can be used. Polyvinyl alcohol has a degree of polymerization of 100 to 5000. Saponification degree 70%
Those mentioned above are preferably used. Further, as the cellulose derivative, for example, methylcellulose, carboxymethylcellulose, hydroxypropylmethylcellulose, etc. are preferably used.

In the present invention, microspherical thermosetting resin particles are carbonized or activated under predetermined conditions, or the microspherical thermosetting resin particles as described above and binder 03) are mixed and granulated to form a granular molded product. It is carried out by carbonization or activation after carbonization.

When obtaining a granular molded body by granulation, microspherical thermosetting resin particles (4) and 60% by weight or less of the binder component CB) are used.

The above components cA) and CB) can be mixed as they are, or water or an organic solvent can be added to component Q3) and thoroughly mixed in the presence of these solvents. Water or an organic solvent is, for example, component (3))
It is also possible to add the components) in dissolved form before mixing. Water or an organic solvent is preferably added to the raw material mixture ((
4) 5 to 30% by weight based on the solid content of 10)), more preferably 8 to 20%! The amount is %. Also, when mixing component (4).

In addition to (2), for example, starch, its derivatives, modified products, etc. may be added to component (4) at 5 to sO! f1%, preferably 1
It can be added in an amount of 0 to 40% by weight. Components such as starch participate in the generation of pores through thermal decomposition during carbonization in a non-oxidizing atmosphere, which will be described later, and act suitably as a pore-forming material. In addition, in producing the molecular sieve carbon of the present invention, for example, ethylene glycol, polyoxyethylene alkyl ether,
A small amount of a surfactant such as a polyoxyethylene fatty acid ester or ammonium carboxylic acid salt, a curing agent for liquid thermosetting resin, a crosslinking agent for polyvinyl alcohol, a plasticizer for extrusion granulation, etc. can be added.

In the step of mixing components (8) and a3), the materials may be mixed using, for example, a ribbon mixer, a type mixer, a cone mixer kneader, or the like. The homogeneous mixture prepared in the above process is then formed into granules.

Molding into granules can be carried out using, for example, a single-screw or twin-screw wet extrusion granulator, a vertical granulator such as a basket reuser, a semi-dry disk pelletizer, or the like.

In particular, granules granulated by a wet extrusion granulator are preferred because they have high particle strength and a high ability to separate molecular sieve carbon after carbonization. The shape of the granules is, for example, cylindrical or spherical. The size of the granules obtained by granulation is not particularly limited, but for example, a cylinder has a diameter of 0.6 to 6 mm.
, about 1 to 10 mm in length, and 0.5 in diameter if spherical.
~10 mm is preferable.

In order to obtain molecular sieve carbon from microspherical thermosetting resin particle powder or granular compacts obtained by granulation, these must be carbonized in a temperature range of 500 to 1100°C in a non-oxidizing atmosphere, or after carbonization. 15Jitf of carbide in the temperature range of 500-1100℃ under oxidizing atmosphere
Activation is performed within a range that reduces the amount of nails within fi%. The non-oxidizing atmosphere in this case is, for example, an atmosphere of nitrogen, argon, helium, or the like. The rate of temperature increase until reaching the maximum treatment temperature in the carbonization step is not particularly limited, but is preferably 5 to 300°C/hr. Further, for example, air, water vapor, carbon dioxide gas, etc. can be used as the oxidizing atmosphere during activation.

By the way, the molecular sieve effect of molecular sieve carbon is due to the fact that the pore diameter of the micropores is in the range of several ^ which is extremely close to the molecular diameter of the adsorbed molecules, and it exhibits selective adsorption characteristics for various substances with different molecular diameters. It is. Therefore, the performance of molecular sieve carbon is determined by the pore size distribution of the micropores, and molecular sieve carbon having a sharp pore size distribution with a pore diameter of usually 10 mm or less, preferably in the range of about 3 to 5 times is preferable. Further, pores with a pore diameter of about 15 to 200X usually do not have a molecular sieving effect and simultaneously adsorb multiple gases coexisting and solutes in a solution. Therefore, the pore diameter is 15
The smaller the pore amount in the range of ~200X, the more preferable.

The molecular sieve carbon of the present invention has a maximum value of the pore distribution of micropores in a region with a pore diameter of 10X or less, preferably 3 to 5X, and a pore volume of 10X or less, preferably 0.1 to 0.7 c.
c/f, more preferably 0.15 to 0.5 co, Q, and the pore volume of pore diameters of 15 to 200X is preferably 0.1 cm or less.

The specific surface area of molecular sieve carbon having the above pore structure is usually 1 as measured by the B, E, and T methods using nitrogen adsorption.
~700m/N, preferably 10-500m”/f
s most preferably about 50 to 350 m2/f.

In contrast, the commonly used specific surface area is 1000-1
600 m'/V activated carbon has a maximum value of the pore size distribution of micropores in a region of about 1 sX or more in pore diameter;
Pore volume in the range 5-200X is 0,4-1.6 cc
/9, and does not have a custom molecular sieve like the molecular sieve carbon of the present invention.

The molecular sieve carbon of the present invention can be easily produced as described above and has excellent adsorption capacity and selective adsorption properties. Therefore, the molecular sieve carbon of the present invention can be used to separate various mixed gases. For example, a gaseous mixture of nitrogen gas and oxygen gas, a gaseous mixture of methane gas and hydrogen gas, a mixture of hydrocarbon isomers such as xylene isomers, butane concrete, butene isomers, a mixture of ethylene and propylene,
It can be used to separate gaseous mixtures of hydrogen gas and methane gas, as well as gaseous mixtures containing argon. More specifically, for example, it can be used to obtain nitrogen gas, oxygen gas, or a gas mixture enriched in either nitrogen gas or oxygen gas from a gas mixture containing nitrogen gas and oxygen gas. Alternatively, it can be used to obtain a gas mixture enriched in methane gas, hydrogen gas, or either methane gas and hydrogen gas from a gas mixture containing methane gas and hydrogen gas. For this purpose, it is desirable to employ a pressure swing adsorption method. In the pressure swing adsorption method, two or three adsorption towers are usually filled with molecular sieve carbon,
The mixed gas can be separated by periodically repeating selective adsorption under increased pressure of about kf/f/am' and regeneration of the adsorbent under reduced pressure or normal pressure. This method separates the above-mentioned mixed gases as well as steam reforming gases.

Ethylene plant off gas, methanol cracking gas.

It is also possible to recover hydrogen from ammonia decomposition gas, coke oven exhaust gas, etc., or recover carbon monoxide from converter exhaust gas.

The present invention will be specifically explained below with reference to Examples.

Example 1 Micro spherical thermosetting resin particle powder (manufactured by Unitika Co., Ltd., UNIPEX C-200) Soot with inner diameter of 60φ x 10
The sample was placed in a 00 mm L electric furnace, heated to a predetermined temperature at 60° C./hr under a nitrogen atmosphere, kept at that temperature for 1 hour, and then cooled in the furnace to obtain a fine powder with a spherical particle shape.

In order to evaluate the molecular sieving properties of this fine carbon powder, the first
The amounts of nitrogen gas and oxygen gas adsorbed were measured using the adsorption property measuring device shown in the figure. In the figure, sample chamber 4 (20
0ml), close valve 11.8, open valve 2.5, degas for 30 minutes, close valve 2.5, open valve 11, and adjust the chamber 5 (200m).
Send oxygen gas or nitrogen gas into the chamber (J7), and when the set pressure (7,OOky/cm") is reached, close the valve 1.
1 was closed and valve 3 was opened, the change in internal pressure was measured over a predetermined period of time, and the adsorption rates of oxygen and nitrogen were determined. In addition, 1 is a vacuum pump, and 6.7 is a pressure sensor.
9 is a recorder, 10 is a pressure gauge, 14.15 is a gas regulator, 16 is a nitrogen cylinder, and 17 is an oxygen cylinder.

As an indicator of nitrogen and oxygen separation performance, the stage weight capacity 1 minute after the start of adsorption is Q+ for nitrogen and Q! for oxygen. Then, the adsorption amount difference ΔQ is determined by the following formula (1) % formula % (1), and the nitrogen adsorption pressure is P+, the tllll base deposition pressure is 2, and the selection coefficient α is determined by the following 2■ Heat treatment temperature during carbonization is Sample 1 obtained at a temperature lower than the temperature specified in the present invention has a small amount of oxygen adsorption, and the adsorption amount difference ΔQ1 and the selection coefficient α are also small, making it undesirable as a molecular sieve carbon. Sample 2.3.4 has oxygen adsorption amount,
Both the adsorption amount difference ΔQ1 and the selection coefficient a are moderate values, and it has practicality as a molecular sieve carbon. It can be seen that sample 3 is particularly superior. In addition, in sample 5, which was obtained at a heat treatment temperature during carbonization that was higher than the temperature specified in the present invention, the selection coefficient α was large, but it was determined from the oxygen adsorption and absorption factors.

The results of Example 1 above are shown in Table 1.

Example 2 Degree of polymerization 1000. Polyvinyl alcohol with a saponification degree of 88% was dissolved in a predetermined amount of hot water to form a 20% by weight aqueous solution.

Apart from this, micro spherical thermosetting a resin particle powder (manufactured by Unitika Co., Ltd., UNIPEX C-200),! -Water-soluble resol resin (manufactured by Showa Kobunshi Co., Ltd., Sydunol BRL-
2854, solid content concentration 60i%), water-soluble melamine resin (manufactured by Sumitomo Chemical Co., Ltd., Sumitex Resin M-3
．． solid content concentration 80% by weight), methyl cellulose powder (product of Shin-Etsu Chemical Co., Ltd.).

Predetermined amounts of Metrose 60SH-4000), potato starch, and ethylene glycol were each weighed.

After mixing the microspherical thermosetting resin particles, potato starch, and methylcellulose powder in a Ni-Goo for 15 minutes, they were mixed with 13 M of polyvinyl alcohol water and water-bathable resol I2! Fat, water-soluble melamine and ethylene glycol were added and mixed for an additional 15 minutes.

The mixed composition was extruded using a twin-screw extrusion granulator (Pelleta Double EXDF-100W, manufactured by Fuji Paudal Co., Ltd.) to produce cylindrical pellets having five types of compositions shown in Table 2. The average particle diameter of the cylindrical pellets is 3φX 6 mm L
Met. After curing and drying this pellet at 90°C for 24 hours, 500f was made into an effective diameter of 100φ x 1000
Place in a mm L rotary kiln and heat at 2A'/min.
The temperature was raised to 860'C at a rate of 30°C/H under a nitrogen stream of 1000 ml, maintained at this temperature for 1 hour, and then cooled in a furnace.

The nitrogen and oxygen separation performance of the granular carbide thus obtained was measured in the same manner as in Example 1. The results are shown in Table 2.

In Table 2, sample 6 has too much binder, sample 1
Sample No. 3 had too little binder and could not be granulated. Moreover, in sample 7, in which the amount of binder was used in an amount larger than the ratio specified in the present invention, O! It can be seen that the adsorption amount is small and it is not preferable as a molecular sieve carbon.

Sample 8.8.10.11.12 has a favorable N! .

0! Adsorption amount and separation characteristics were obtained, and the characteristics of sample 9 were particularly excellent.

Example 3 A cylindrical pellet precursor with an average particle diameter of 3 mmφ x 8 mm L, which was granulated with the same composition and under the same conditions as samples No. 9 of Example 2, was placed in a rotary kiln of 100φ×1000 mm L, and was heated at 2I! The temperature was raised to a predetermined temperature at a temperature increase rate of 30° C./H while flowing nitrogen at a rate of 30° C./min, maintained at this temperature for 1 hour, and then cooled in a furnace to eliminate the carbide.

Table 3 shows the nitrogen and oxygen separation ability of the carbide.

Sample 14, which was obtained at a heat treatment temperature during carbonization lower than the temperature specified in the present invention, had a small amount of oxygen adsorption;
In addition, the adsorption amount difference ΔQ9 and the selection coefficient a are small, making it undesirable as a molecular sieve carbon.

Samples 9.15.16 have oxygen adsorption amount, absorption Wffi difference ΔQ
It can be seen that the 1 selection coefficient α is large, making it practical as a molecular sieve carbon, and the custom-made sample 3 is particularly excellent.

In addition, in sample 17, which was obtained at a heat treatment temperature during carbonization higher than the temperature specified in the present invention, the selection coefficient α is large, but the oxygen adsorption amount and adsorption amount are combined with sample 8 of Example 4 and Example 5. Using the granular molecular sieve carbon prepared in the same manner as above, an experiment was conducted to separate nitrogen and oxygen in the air by the pressure swing absorption (PEA) method.

A schematic diagram of the P8A apparatus used in this experiment is shown in FIG. 2. The size of the adsorption tower is 63φ x 1200mmL in inner diameter, and 2
The above molecular sieve carbon (specific surface area 120
m”/f).The packing density is o, eog/
It was c-.

First, air compressed by a compressor is sent to an adsorption tower.
The pressure during adsorption is 6kyf/am”・G in gauge pressure,
Desorption (exhaust) regeneration is performed using a vacuum pump at approximately 100 torr.
This was carried out by reducing the pressure to r.

The P8A operation was carried out in four steps: pressure equalization (pressurization) - adsorption - pressure equalization (depressurization) - exhaust, and switching between each step was performed by automatically controlling a solenoid valve with a sequencer. The fourth PEA operating condition
Table: This is shown.

In this experiment, the number of times the product nitrogen gas was removed was 11! /min
purity 88.9% (N@+Ar), 21/min
It was 87.5%.

Example 5 A precursor having the same composition as in Example 4 was carbonized in a nitrogen atmosphere at 900° C. for 1 hour in the same manner as in Example 3, and then activated in a steam atmosphere for 10 minutes.

The sample taken out after cooling the furnace had a weight of 5.4 based on the carbide weight.
It showed a weight decrease of % M amount.

The granular molecular sieve carbon obtained as described above has a specific surface of 1fR680m"/f and a packing density of 0.58 jF/a.
It was m'.

An experiment was conducted in which the molecular sieve carbon was filled in the same P8A apparatus as in Example 4, and a raw material gas consisting of 70% hydrogen gas and 30% methane was separated by the PEA method.

The raw material gas pressurized by the compressor is introduced into the adsorption tower, and according to the operating conditions shown in Table 4, the two towers are alternately subjected to four steps: pressure equalization (pressurization) - adsorption - pressure equalization (depressurization) - exhaust. The P8A operation was performed by repeating the steps. Adsorption pressure is 5kyf/
am”・G, and regeneration is performed using a vacuum pump at approximately 100 torr.
This was done by reducing the pressure to r.

The purity of the product hydrogen gas in this experiment was 241!
99.5% at /min, 89.0% at 41/min
Met.

As described above, hydrogen and methane could be separated well using the granular molecular sieve carbon obtained in the present invention.

Table 4

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the adsorption characteristic measuring device used in Examples 1, 2.3, and FIG. 2 is a schematic diagram of the pressure swing adsorption (PEA) device used in Examples 4 and 5. In Figure 1, 1... Vacuum pump, 2, 3. 8. 11, 12° 13.
...Valve, 4...Sample chamber, 6...Adjustment chamber, 6.7
...Pressure sensor 9...Recorder, 10...Pressure gauge, 14.16...Gas regulator 16...
Nitrogen cylinder, 17...Oxygen cylinder. In Fig. 2, 1...Air compressor, 2...Air dryer, 3゜3a...Adsorption tower, 4.4a...First on-off valve, 5゜5a...Inlet pipe, 6 ...Vacuum pump, 7.7
a. 10+ 10a, I Sr I Sa, 15.17...
- Opening/closing valve, 8... Suction path pipe, 9.9a... Extraction pipe, 11... Main pipe, 14... Reservoir tank, 16... Product gas extraction pipe. Figure 1

Claims (1)

[Claims] A microspherical thermosetting resin powder whose surface is partially or entirely coated with an inorganic salt substantially insoluble in water and whose particle size is 500 μm or less is prepared, and this thermosetting resin particle powder or this thermosetting resin powder is prepared. A method for producing molecular sieve carbon, which comprises firing a granular molded product obtained by granulating a curable resin powder together with 60% by weight or less of a binder in a non-oxidizing atmosphere in a temperature range of 500 to 1100°C.