JP2003104720A - Molecular sieve carbon and pressure swing adsorption apparatus using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide high performance molecular sieve carbon as performance of a pressure swing adsorption apparatus is improved and its usable field is expanded. SOLUTION: The pellet length of cylindrical molecular sieve carbon for the pressure swing adsorption apparatus is 0.5-1.5 mm, preferably outside diameter of the pellet is 0.5-1.8 mm, and has an inside structure united three- dimensionally and irregularly with a lot of primary carbon particles whose particle diameter is 0.1-50 μm. The whole micropore volume is 0.1-0.7 ml/g, a rate of micropore volume whose pore diameter is 2.8-5.0 Å to the whole micropore volume is 60 vol.% or more, particle bulk density is 0.7-1.2 g/cm<3> and carbon content is 80 wt.% or more.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention has an outer diameter of 0.5 to 1.8.
The present invention relates to a cylindrical molecular sieving carbon having a size of 0.5 mm and a height of 0.5 to 1.5 mm, and a pressure swing adsorption device (hereinafter abbreviated as PSA device) using the carbon.

[0002]

2. Description of the Related Art In recent years, a pressure swing adsorption method (hereinafter referred to as PSA method) has been developed and put into practical use as a technology for separating nitrogen and oxygen in air.

The PSA method is usually a method in which two or more adsorption towers are filled with an adsorbent to selectively adsorb the adsorbent under a pressure of about 3 to 10 kgf / cm ² and regenerate the adsorbent under a reduced pressure or atmospheric pressure. This is a method of separating a specific component in the mixed gas by repeating the cycle periodically.

In 1948, Emmett (PHEmmett: chem.Re
(v.43, 69) has obtained many molecular sieving carbons by carbonizing vinylidene chloride, and many manufacturing methods of molecular sieving carbons have been proposed up to the present day. In recent years, coal,
It has become possible to industrially manufacture natural products such as coconut shells, and molecular sieving carbon mainly composed of synthetic polymers.

For example, Japanese Examined Patent Publication (Kokoku) No. 52-18675 discloses that coke having a volatile content of up to 5% is added with pyrolytic hydrocarbon and treated at a temperature of 600 to 900 ° C. A method of making molecular sieving carbon by depositing carbon in the pores of the coke is disclosed.

In Japanese Patent Publication No. 62-17690, coconut shell charcoal powder is granulated using coal tar or coal tar pitch as a binder and carbonized at 600 to 900 ° C., and carbonized carbon is washed with mineral acid. After washing with water and drying, impregnate coal tar with 10-60 at 600-900 ° C.
A method for producing molecular sieving carbon is disclosed, which comprises performing heat treatment for minutes and then cooling in an inert gas.

[0007] As described above, technological development of molecular sieving carbon has progressed and industrial production is being carried out. Currently, 80 vol% of the whole is used in an industrial production of 1 to 4 mm in outer diameter and pellet length. It is a cylindrical pellet of 2 to 10 mm.

Further, Japanese Unexamined Patent Publication No. 06-154595 discloses a high-performance pressure swing adsorption molecular sieving carbon by reducing the outer diameter.

However, the effect of pellet length on the separation performance of molecular sieve carbon for pressure swing adsorption has not been examined.

[0010]

In recent years, as the performance of pressure swing adsorption devices has become higher and the fields of use have expanded, there has been a demand for higher performance of molecular sieving carbon.

[0011]

The present invention has a height of 0.
It can be achieved with columnar molecular sieving carbons ranging from 5 to 1.5 mm. Further, 80 vol% or more of the whole is columnar molecular sieving carbon having a height in the range of 0.5 to 1.5 mm or the molecular sieving carbon described above having a diameter of 0.5 to 1.8 mm. Can be achieved.

Further, it has an internal structure in which a large number of primary carbon particles having a particle size of 0.8 to 120 μm are randomly and three-dimensionally integrated, and the total volume of micropores is 0.1 to 0.7 ml / g. , The micropore volume in the range of 2.8 to 5.0Å in the pore diameter is 60 vol% or more of the total volume of the micropores, and the carbon content is at least 8
It can also be achieved by the molecular sieving carbon according to claims 1 to ³ , which has a particle bulk density of 0.7 to 1.2 g / cm ³ at 0% by weight or more. Further, the main raw material may be thermosetting phenol resin powder.

High performance can be achieved by the pressure swing adsorption / desorption device equipped with these molecular sieving carbons.

Here, "80 vol% of the whole" means that the ratio of the specified carbon in the specified amount of molded carbon is 80% of the total in terms of volume.

The molecular sieving carbon of the present invention is formed columnar carbon, and the height is the length of the columnar carbon in the height direction, and the pellet length is the height direction of the pelletized cylinder. Refers to the length of.

The raw material of the molecular sieving carbon includes coke, phenol resin and the like. The molecular sieving carbon of the present invention is preferably a thermosetting phenol resin powder, more preferably a phenol resin having a particle size of 1 to 150 μm. It is composed of spherical primary particles or their secondary agglomerates, and at least 50% by weight of the whole particles have a size capable of passing through a 100 Tyler mesh sieve, and have a peak absorption intensity of 1600 cm ^{-1 in} the infrared absorption spectrum by the KBr tablet method. ₁₆₀₀ ,
900~1015cm formula D ₉₀₀ the greatest peak absorption intensity in the range of ^-1 to the peak intensity of D ₉₀₀ ~ _1015, 890cm ^-1 when expressed by _{D 890 ~ 1015 / D 1600 =} 0.2~9.0 It is a thermosetting phenolic resin powder specified by satisfying D ₈₉₀ / D ₁₆₀₀ = 0.09 to 1.0 and having a solubility in methanol under reflux of 50% by weight or less.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Since molecular sieving carbon is usually formed by forming raw material powder into pellets using a binder or the like and then carbonizing and firing, carbon particles are aggregated and coalesced to form pellets. However, it is not limited to pellets,
For example, it can be formed by compression by tableting.

The carbon primary particles in the present invention are the above-mentioned pellets obtained by carbonizing a thermosetting resin such as phenol resin which is a fine powder of raw material, coke derived from anthracite, brown coal, peat, coconut shell charcoal and the like. It refers to the fine carbon particles that are formed. The particle size of the carbon primary particles is preferably 0.1 to 50 μm, more preferably 0.1 to 30 μm, and most preferably 2 to 20 μm.

In producing the molecular sieving carbon of the present invention, the inventors of the present invention, in addition to the particle size of the raw material fine powder, the amount of the binder compounded, the amount of the surfactant used, and the specifications of the granulation equipment,
For example, by conducting various studies on the cutting method of the granulated product, it was possible to successfully control the pellet length of the cylindrical pellet, which was difficult in the past, and to obtain a high-strength molecular sieve carbon with a pellet length of 0.5 mm to 1.5 mm. This enables the manufacture of

This manufacturing technique is disclosed in, for example, Japanese Patent Laid-Open No. 63-20.
A method of granulating a spherical phenol resin disclosed in Japanese Patent Laid-Open No. 1008 together with a phenol resin having a solid content of 40% by weight or less to form a granular molded product and firing the molded product in a non-oxidizing atmosphere, or JP-A-62-62. -59510, US Pat. No. 505957, JP-A-1-61306, JP-A-3-
40912, JP-A-3-141111, and JP-A-4-2.
It can be applied to the method disclosed in Japanese Patent No. 605 or other known methods.

The ratio of cylindrical molecular sieving carbon having a pellet length of 0.5 to 1.5 mm is preferably 80 vol% or more of the whole, and preferably has an outer diameter of 0.5 to 1.8 mm and a particle diameter of 0. It is preferable that it has an internal structure in which a large number of carbon primary particles of 0.1 to 50 μm are three-dimensionally irregularly united.

The ratio of the molecular sieving carbon having a pellet length of 0.5 to 1.5 mm to the whole is usually 80 vol% or more,
It is preferably 90 vol% or more.

Although the classification of pores of activated carbon and molecular sieving carbon is not always constant according to the literature, in the present invention,
Macropores are pores with a pore size of more than 500Å, which are mainly composed of interstices of carbon primary particles, and pores of 20Å to 500Å which exist in the primary particles inexhaustibly in all directions are branched from mesopores and mesopores. The pores of less than 20Å are defined as micropores.

The adsorption isotherm measured by the measuring method described later was processed using the Dubinin-Astakhov equation to determine the micropore volume in the molecular sieving carbon of the present invention.

The molecular sieving carbon of the present invention is preferably
The total volume of micropores is 0.1 to 0.7 ml / g, and the volume of micropores having a pore diameter of 2.8 to 5.0Å is 60 vol% or more of the total volume of micropores, and more preferably micropores. Total volume of pores is 0.12-0.5ml / g, pore diameter is 2.8-5.0Å
The volume of the micropores is 70vol of the total volume of the micropores.
% Or more, and most preferably, the total volume of micropores is from 0.15 to
The micropore volume in the range of 0.3 ml / g and the pore diameter of 2.8 to 5.0Å is 80 vol% or more of the total volume of the micropores.

The molecular sieving carbon is for separating molecules such as nitrogen and oxygen or nitrogen and carbon dioxide, which have a very small difference in molecular diameter, and in this case, a micropore having a pore diameter in the range of 2.8 to 5.0Å. Pore volume is very important.

The molecular sieving carbon of the present invention has, as a compositional characteristic, preferably a carbon content of 80% by weight, more preferably 85% by weight, and most preferably 90% by weight. Has a carbon content of.

[0028] The molecular sieving carbon of the present invention is preferably a particle bulk density 0.7 to 1.2 g / cm ^3, more preferably 0.8~1.15g / cm ^3, and most preferably 0. 9-1.
It is 1 g / cm ³ .

[0029]

According to the studies made by the present inventors, molecular sieving carbon of a cylindrical pellet having a pellet length of 0.5 to 1.5 mm can be obtained, and the carbon can significantly improve the device performance.

Since the molecular sieving carbon of the present invention has excellent adsorption capacity and selective adsorption characteristics, it can be used not only for gas mixture of nitrogen and oxygen but also for separation of various mixed gases. For example, the specific gas component can be separated from a mixture of hydrocarbon isomers such as butane isomers and butene isomers, a mixture of ethylene and propylene, and the like.

In addition to the above-mentioned separation of mixed gas, steam reforming gas, off gas of ethylene plant,
It can also be used for hydrogen recovery from methanol decomposition gas, ammonia decomposition gas, coke oven exhaust gas, etc., or separation and recovery of carbon dioxide from boiler exhaust gas of a thermal power plant.

[0032]

EXAMPLES The measuring methods used in the present invention are shown below. (1) Micropore volume measurement method The micropore volume of the molecular sieving carbon of the present invention is measured using a fully automatic gas adsorption measuring device (BELSORP-28, manufactured by Nippon Bell Co., Ltd.) with oxygen (molecular diameter 2.8Å). ), Ethane (molecular size 4.
0 Å), isobutane (molecular diameter 5.0 Å) 0-760 mmHg,
The adsorption isotherm at 298K was measured, and D in equations (1) and (2)
It was done by organizing using the ubinin-Astakhov formula.

W / W ₀ = exp {-(A / E) ⁿ } (1) A = RTln (P ₀ / P) (2) where W; adsorption amount at equilibrium pressure P W ₀ ; ultimate adsorption amount A Adsorption potential E; Adsorption characteristic energy R; Gas constant T; Measurement temperature P ₀ ; Saturated vapor pressure P; Equilibrium pressure n; Constant (n = 2 for oxygen, n = for ethane and isobutane)
3) (2) Method of measuring adsorption amount The adsorption amount of oxygen and nitrogen of the molecular sieving carbon of the present invention was measured using the adsorption characteristic measuring device shown in FIG.

In the figure, the sample chamber (4) (200 ml) has 3
Insert the sample of g, close valves (18), (11) and (8), open valves (2) and (3) and degas for 30 minutes, then
(2) and (3) were closed and the valve (11) was opened, and the change in internal pressure during a predetermined time was measured to determine the oxygen concentration and the nitrogen adsorption rate.

Incidentally, (1) is a vacuum pump, (6) and (7) are pressure sensors, (9) is a recorder, (14) and (15) are gas regulators, (16) is a nitrogen cylinder, and (17) ) Is an oxygen cylinder.

As an index showing the separation performance of nitrogen and oxygen, the adsorption amount one minute after the start of adsorption was Q ₁ for nitrogen and Q _{2 for} oxygen.
Then, the adsorption amount difference ΔQ was determined by the following formula (3) ΔQ = Q ₂ −Q ₁ (3). (3) Carbon content measurement The carbon content of the molecular sieving carbon of the present invention is Yanagimoto CH
It was analyzed by N coder, MT-3.

Example 1 10 parts by weight of a phenol resin powder having an average particle diameter of 18 μm was mixed with an aqueous solution of melamine resin (Sumitex Resin M-3, manufactured by Sumitomo Chemical Co., Ltd., solid content concentration 80% by weight) as a solid content. 8 parts by weight, degree of polymerization 170
0, polyvinyl alcohol with a saponification degree of 99% is warmed to 2
20 parts by weight of an aqueous polyvinyl alcohol solution dissolved so as to be a 0% by weight aqueous solution, 2 parts by weight of potato starch, and 0.7 parts by weight of a surfactant (Perex NB-L manufactured by Kao Corporation) were weighed.

Of the above raw materials, an aqueous melamine resin solution, an aqueous polyvinyl alcohol solution, potato starch and a surfactant were mixed for 5 minutes, and the phenol resin powder was added to the mixture and further mixed for 10 minutes.

This mixed composition was extruded by a twin-screw extrusion granulator (Peretta Double EXDF-100 type manufactured by Fuji Paudal Co., Ltd.), and after firing, the outer diameter was 1.0 mmφ and the pellet length was 0.
2mm (Sample 1), 0.5mm (Sample 2), 1.0mm (Sample 3),
An attempt was made to granulate four kinds of molecular sieving carbon by cutting so as to have a size of 1.5 mm (Sample 4). Here, a pellet having a length of 0.2 mm, which is shorter than the range of the present invention, could not be cut while maintaining a cylindrical shape, and could not be pelletized into a pellet.

Each of these pellets was heated at 290 ° C. for 3 hours.
After drying for an hour, put it in a rotary kiln with an effective diameter of 750 mmφ x 4250 mmL and under a nitrogen stream at 30 ° C.
/ H to 800 ℃, hold at the temperature for 1 hour,
The furnace was cooled under a nitrogen atmosphere.

In order to evaluate the molecular sieving characteristics of the samples 2 to 4 thus obtained, the adsorption amounts of oxygen and nitrogen were measured by the adsorption characteristic device shown in FIG. The measurement results are shown in Table 1.

Further, samples 2 to 4 were used to carry out an experiment for separating nitrogen and oxygen in the air by the PSA method. Used in this experiment
A schematic diagram of PSA is shown in FIG. Adsorption tower size is 30mm inside diameter
φ × 800 mmL, and two adsorption towers were filled with molecular sieving carbon.

First, the air compressed by the compressor was sent to the adsorption tower, the pressure of the adsorption tower was set to 9.5 kgf / cm ² G by gauge pressure, the supply rate was fixed at 16 NL / min, and the extraction rate was fixed at 4 NL / min. The PSA operation was carried out in four steps of vertical pressure equalization-adsorption-vertical pressure equalization-regeneration (purge), and the switching of each step was performed by controlling the solenoid valve with a sequencer. The obtained product nitrogen was evaluated by measuring the oxygen concentration with an oximeter. The PSA operating conditions are shown in Table 2. The measurement results are shown in Table 1.

In all the samples, the oxygen concentration of nitrogen was low and the air separation ability was high.

[0045]

[Table 1]

[0046]

[Table 2]

Comparative Example A sample 5 having an outer diameter of 1 mm, a pellet length of 2 mm, 2.5 mm and 3 mm was prepared by the same manufacturing method as in Example 1.
6 and 7 were created. Further, the obtained sample was subjected to an experiment for separating nitrogen and oxygen in the air by the PSA method in the same manner as in Example 1.

From the PSA evaluation results of Samples 2 to 7, a graph in which the pellet length is the x-axis and the oxygen concentration is the y-axis is shown in FIG. Figure 3
From the range of oxygen concentration expected in Samples 5, 6 and 7,
Surprisingly, the oxygen concentration of Samples 2 to 4 is much lower. It can be seen that controlling the pellet length within the scope of the claims of the present invention dramatically improves PSA performance.

Example 2 The sample 3 obtained in Example 1 was subjected to micropore volume measurement, bulk density measurement, and carbon content measurement.

The results are shown in Table 3. Micropore volume is 0.1
˜0.7 ml / g, particle bulk density is 0.7 to 1.2 g / cm ³ , and carbon content is 80% by weight or more.

[0051]

[Table 3]

(Embodiment 3) By the same manufacturing method as in Embodiment 1,
Samples 8, 9 and 10 having a pellet length of 1 mm and an outer diameter of 0.5 mm, 1 mm and 1.5 mm were prepared. Further, the obtained sample was subjected to an experiment for separating nitrogen and oxygen in the air by the PSA method in the same manner as in Example 1.

The results are shown in Table 4. All the samples had a low oxygen concentration of nitrogen and showed high air separation ability.

[0054]

[Table 4]

[Brief description of drawings]

FIG. 1 is a diagram showing an adsorption characteristic measuring apparatus used in Examples.

FIG. 2 is a diagram showing a pressure swing adsorption (PSA) device used in Examples.

[Figure 3] From the PSA evaluation results, the pellet length is x-axis and the oxygen concentration is
It is a graph figure made into the y-axis.

[Explanation of symbols]

1 Vacuum pump 2, 3, 11, 18 Solenoid valve 4 Data chamber 5 Adjustment chamber 6, 7 Pressure sensor 8, 12, 13 Valve 9 Recorder 10 Pressure gauge 14,15 Gas regulator 16 Nitrogen cylinder 17 Oxygen cylinder 21 Air compressor 22 Air dryer 23, 23a Adsorption tower 24, 24a, 27, 27a, 30, 30a, 33, 33
a, 35 Solenoid valves 25, 25a, 26, 28, 29, 29a, 31, 32
Piping 34 Product tank 36 Pressure regulator

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4D012 BA04 CA03 CA05 CA06 CA12                       CA20 CB16 CD07 CG05 CJ01                       CJ02                 4G046 CA04 CB02 CB05 CB08 CC01                 4G066 AA04B AB30 AC01A AC12A                       AC25A BA01 BA20 BA24                       BA25 CA27 CA37 DA03 EA09                       GA14                 4G073 BA62 BD18 CZ53 GA08 GA11                       GA13 GA14 GB07 UA06

Claims (7)

[Claims] 1. A columnar molecular sieving carbon having a height in the range of 0.5 to 1.5 mm. 2. The height is 0.5 to 50% of the whole.
Columnar molecular sieving carbon in the range of 1.5 mm. 3. The molecular sieving carbon according to claim 1, which has a diameter of 0.5 to 1.8 mm. 4. A large number of carbon primary particles having a particle size of 0.8 to 120 μm.
It has an internal structure in which the children are three-dimensionally and irregularly united.
However, the total volume of micropores is 0.1 to 0.7 ml / g, and the pore diameter is 2.
The micropore volume in the range of 8 to 5.0Å is the total micropore volume.
60 vol% or more of the product, carbon content of at least 80
Bulk density of particles is 0.7 to 1.2 g / cm at a weight% or more. ³To be
The molecular sieving carbon according to any one of claims 1 to 3, wherein 5. The molecular sieving carbon according to claim 1, wherein the main raw material is a thermosetting phenol resin powder. 6. A thermosetting phenolic resin powder comprising (A) spherical primary particles of phenolic resin having a particle size of 1 to 150 μm or a secondary agglomerate thereof, and (B) at least 50% by weight of 100 Tyler mesh. The size is such that it can pass through a sieve, and the infrared absorption spectrum by the (C) KBr tablet method is 16
The peak absorption intensity at 00 cm ^-1 is D ₁₆₀₀ , 900 to 1015c
The largest peak absorption intensity in the range of m ^-1 is D ₉₀₀ ~ ₁₀₁₅ ,
When the peak intensity at ₈₉₀ cm ⁻¹ is represented by D ₈₉₀ , the following formulas D ₉₀₀ to ₁₀₁₅ / D ₁₆₀₀ = 0.2 to 9.0 D ₈₉₀ / D ₁₆₀₀ = 0.09 to 1.0 are satisfied, and ( D) The molecular sieving carbon according to claim 4 or 5, characterized by having a solubility in methanol under reflux of 50% by weight or less. 7. A pressure swing adsorption / desorption device comprising the molecular sieving carbon according to claim 1.