JPS616108A - Carbon for molecular sieve - Google Patents

Abstract

PURPOSE:To obtain the titled carbon having a favorable pore structure, superior heat resistance, chemical resistance and molecular sieve performance by carbonizing a plastic composite body consisting of PVA-base resin and phenol resin in a specified ratio at a specified temp. in a nonoxidizing atmosphere. CONSTITUTION:The plastic composite body consisting of 10-70wt% PVA-base resin and 30-90wt% phenol resin is carbonized at 500-700 deg.C, preferably about 530-670 deg.C, more preferably about 550-650 deg.C in a nonoxidizing atmosphere, and it is activated as required at 500-700 deg.C in an oxidizing atmosphere of steam, gaseous CO2 or the like to such a degree that the weight of carbide is reduced by <=15%. Molecular sieve carbon having continuous macropores of 1-500mum diameter having a network structure is obtd. The carbon has 0.1-0.8g/cm<3> apparent density and 50-95% porosity, the maximum value in the fine pore diameter distribution is <=10Angstrom , and the volume of pores of 15-200Angstrom diameter is <=0.1cm<3>/g.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is characterized in that the polyvinyl alcohol resin is
carbonized or carbonized and activated synthetic resin composite consisting of 30 to 90% by weight of phenolic resin, maximum pore size distribution in a region with a pore diameter of 10A0 or less]
The present invention relates to a molecular sieve carbon having a pore diameter of 15 to 200A0 and a pore volume Te1 of OAd/V or less.

Conventionally, silica-alumina zeolite has been widely used as an adsorbent having a molecular sieving effect, and plays an important role in gas separation and purification.

However, zeolite-based molecular sieves are heat resistant.

It has the disadvantage of poor chemical resistance, strong selective adsorption to polar substances such as water, and no molecular sieving effect in the presence of polar substances. In contrast to such zeolite-based molecular sieves, in recent years (11) it has become possible to manufacture molecular sieves made from polar and hydrophobic carbon, which has excellent heat resistance, iFl chemical properties, and can be used even in the presence of polar substances. It is attracting attention as a sieve.However, this molecule can be sieved.

As a method for producing synthetic E II & post-coalescence from these polyvinyl alcohol resins and phenolic resins,
A method in which a polyvinyl acetal such as polyvinyl formal, polyvinyl benzal, etc. is produced from polyvinyl alcohol, and then a predetermined amount of phenol resin is applied to the resin. After uniformly mixing the powdered phenol resin, a method may be used in which the mixture is reacted and cured as it is, or a crosslinking agent is added and the mixture is reacted and cured. In addition, by adding pore-forming materials such as starch-9 starch modified products, starch derivatives, or water-soluble metal sieves during the production of these synthetic resin composites, synthetic resin composites with continuous macropores in a network structure can be produced. It can be manufactured. The manufacturing method is disclosed in, for example, Japanese Patent Publication No. 58-54082, Japanese Patent Publication No. 57-5110
Publication No. 9.

It is sufficient to follow the method disclosed in Japanese Patent Application Laid-Open No. 58-172209 or other known methods. In short, polyvinyl alcohol resin is 10 to 70% by weight, and phenolic resin is 30 to 9% by weight.
Any synthetic resin composite consisting of 0% by weight may be used.

The molecular sieve carbon of the present invention is polyvinyl alcohol-based & JIFi-10 obtained by the above-mentioned 7j'11.
A synthetic resin composite consisting of ~・70% by weight and 30 to 90% by weight of phenol pine resin with a non-oxidizing backing: 500~ under an ambient atmosphere
Carbonization is carried out in the temperature range of 700°C, or after carbonization, the weight loss of the carbide is within 15ujF-% in the temperature range of 500 to 700"C. Obtained by activating within a range.

The details of the mechanism by which molecular sieve charcoal 1 is produced from the synthetic resin composite porous material are not clear, but the content of polyvinyl alcohol resin in the synthetic resin composite porous material is 10% by weight.
If less than 1, practical molecular sieve carbon cannot be obtained even if the moss, ashing, or activation conditions are appropriately selected. Therefore, gasification by thermal decomposition of polyvinyl alcohol-based pine resin is effective in forming micropores that have a molecular sieve effect. It is thought that it plays an important role in the production.

If the content of polyvinyl alcohol resin increases, the carbonization yield of the synthetic resin composite porous body will decrease, and the shape retention and strength of the obtained molecular sieve carbon will decrease, so it is difficult to use a practical polyvinyl alcohol type f)1. The fat content is 70% by weight or less.

The polyhinyl alcohol-based &j fat of the present invention 10-70%, phenol (30-902%)
By increasing the temperature of the synthetic resin composite porous body made of the following materials at a temperature increase rate of 1, the thermal dissolution of the synthetic horse chestnut resin composite progresses from around 200°C, and especially at around 300 to 500°C. During this temperature rising process, carbonization, which is a thermal decomposition residue, occurs: 1 full micropores are generated on the surface of z, and these micropores become more obvious by activation in the temperature range of 500 to 700°C. How to do it. pore volume and chain pores of micropores,
The '41' diameter is defined by the nitrogen adsorption crosstalk and Ke, which will be described later.
This is an analysis using the lvin formula, and according to the above analysis method, the number of micropores with a diameter of 10 A0 or less is 5.
Carbonization in the temperature range of 00 to 700°C usually produces a pore volume of about 0.01 to 0°1d/2, but this pore volume and pore diameter depend on the carbonization temperature in a non-oxidizing atmosphere. As the temperature rises, the carbonization temperature rises to over 700°C, making it less practical as a molecular sieve carbon. Therefore,
The carbonization temperature in a non-oxidizing atmosphere to produce molecular sieve carbon is 500 to 700°C, preferably 53°C.
The temperature is 0 to 670°C, more preferably 550 to 650°C.

Furthermore, the pore diameter of micropores generated by carbonization in a non-oxidizing atmosphere also depends on the temperature increase rate, and the pore diameter tends to increase as the temperature increase rate increases. Therefore, in producing molecular sieve carbon, it is preferable that the temperature increase rate be slow. Normally, the temperature increase rate in the temperature range of 200°C or higher is preferably 120°C/11r or less, preferably 90°C/'hr or less, and most preferably 60°C/hr.
less than hr.

The carbide obtained as described above can be used as it is as a molecular sieve carbon, but the carbide is further heated under an oxidizing atmosphere such as a steam atmosphere or a carbon dioxide atmosphere.
By activating in the temperature range of ~700°C, the number of micropores with a pore diameter of 10 A' or less can be significantly increased, and therefore the molecular sieving ability can be significantly improved.

However, when the activation temperature exceeds 700°C, the pore diameter of the micropores increases, the maximum value of the pore size distribution shifts to the larger pore size, and the pore diameter ranges from 15A' to 200A'.
The pore volume in the region also increases, the selective asorption property is lost, and the molecular sieving effect disappears.

Further, when the g-activation lA degree is 500° C. or less, the activation is extremely impractical because the activation is only 1M or 1M.

Therefore, 1. War temperature 1 is 500-700
Must be in the range of 530 to 6 °C, preferably 530 to 6
70°C, most preferably -j L < is 550-650°C.

Furthermore, even in the case of activation in the temperature range of 500 to 700°C, if the amount of displacement due to activation exceeds 15ifi% of the weight of the carbide obtained by cementation in a non-oxidizing atmosphere, the micropores will be reduced. The pore diameter increases and the molecular sieving effect disappears. Therefore, even in the case of activation in the temperature range of 500 to 700°C, heavy j! The reduction must be within 15 folds of carbide before activation, preferably 12
Within % by weight, most preferably within 10% by weight.

Normally, the pore volume and pore size distribution of adsorbents with fine pores such as activated carbon and silica gel are nitrogen gas.

It is determined from the adsorption isotherm of ethane gas, butane gas, etc. Most commonly, nitrogen gas is used as the adsorbent gas and helium gas is used as the carrier gas, and the relationship between the amount of nitrogen gas adsorbed into the pores of the adsorbent and the nitrogen partial pressure is determined by cooling the adsorbent to the temperature of liquid nitrogen. An adsorption isotherm is obtained.

As a method for determining pore volume and pore radius from adsorption isotherms, the <Kelvin equation has been proposed based on capillary condensation, and analysis based on this equation is generally performed.

Po Saturated vapor pressure when the adsorbed gas condenses into the pore Po Saturated vapor pressure of the adsorbed residue in normal conditions γ Surface tension■ Monomolecular liquid nitrogen gas constant T Absolute temperature rkZ Kelvin radius of the pore The Kelvin radius requires correction for adsorption other than capillary condensation, and for example, Higuchi's method of correcting only monomolecular layer adsorption or a correction method using the HalseY equation are often used. To capillary contraction
The applicable range of Kelvin formula is lol! TV! It is said that the pore diameter is about 40° to 600° (Kelvi
Although a strict pore radius measurement method that can replace the n equation has not yet been established, analysis using the Kelvin equation is often used even in the region of pore diameters of 40A0 or less.

The analysis of pore diameter and pore size distribution in the present invention is carried out by Ke
The lvin formula is applied to pore diameters of up to 10 A'' in combination with its commonly used correction method.

Adsorbent pores are usually called micropores, macropores, transitional pores, etc. depending on their size.
In the present invention, pores with a pore diameter of 200A0 or less are referred to as micropores, and pores with a pore diameter of 200 to 1000A0 (=O01 μm)
The pores are transitional pores, pore diameter 100QA0
The above pores are defined as macropores.

Molecular Sieve The molecular sieve effect in carbon has a φ range of several angstroms in which the diameter of the micropores is extremely close to the molecular diameter of the adsorbed molecules, and exhibits selective adsorption characteristics for various substances with different molecular diameters. This is due to a number of reasons. Therefore, the performance of molecular sieve carbon is determined by the pore size distribution of the micropores, and carbon having a sharp pore size distribution with a pore diameter of usually 10 A0 or less, preferably in the pore diameter range of 3 to 5 A' is used as molecular sieve carbon. Most preferred.

Moreover, pores with a diameter of about 15 to 200 A' do not have a molecular sieving effect, and simultaneously adsorb coexisting gases and different solutes in the solution.

Therefore, the smaller the number of pores with a pore diameter in the range of 15 to 200 A', the better the performance of the molecular sieve.

Now, the commonly used specific surface area 1. oOo~1.5
In activated carbon of 00m'15', the maximum value of the pore size distribution of micropores is in the region of pore diameter of about 15 A0 or more, and the pore volume in the range of pore diameter of 15 to 200 A' is 0.15 to 200 A'.
However, the molecular sieve carbon of the present invention is about 41! ! Hole iE) Diameter 10A'l! The pore size distribution of micropores in the lower region is white, and the pore diameter is 15~2.
The pore volume of the &11 area of 00A' is 0.1 i/y or less, and has an exceptional molecular sieving effect.

As mentioned above, the smaller the pore volume in the pore diameter range of 15 to 20 OA' is, the more preferable it is, preferably 0.07 to 2/2 or less, most preferably 0.05 ci/y or less. Also,
The specific surface area of the molecular sieve carbon of the present invention is not particularly limited, but is usually 100 to 500 n/2 for carbonized products and 20 n/2 for activated products.
It is about 0 to 800 r&/l.

In addition, the molecular sieve element of the present invention has interconnected macropores in a network-like structure by using a known porous material manufacturing method during the production of a synthetic resin composite consisting of polyvinyl alcohol-based 11fff HD hyphenol and fat. Narue 11
1F? It can be made into a porous body. This synthetic resin?
By carbonizing and activating the V joint pores under the conditions of the present invention, it is possible to obtain molecular sieve carbon having #'ifj-shaped Ih structure and continuous macropores.

The molecular sieve carbon usually has an apparent density of 0.1 to 0.8y.
/σJ, porosity 50-95%, average pore diameter 1-5
．． 00μm, preferably apparent density 0°20~0
．． 79/oi, porosity 60-90%, macroporosity E-r θ diameter 5-400 μm, most preferably pore density 0.25-0.697 cd, porosity 65-400 μm.
85%, and the average diameter of the mouth pores is 10 to 300 μm.

Furthermore, in producing the molecular sieve carbon of the present invention, thermosetting resins such as melamine resin, furan resin, etc. may be used in order to improve moldability, dulling properties, and workability within the range without losing its properties. A small amount of silica, alumina,
A small amount of inorganic fine powder such as silicon carbide may be added.

The molecular sieve carbon obtained by the present invention takes advantage of its excellent molecular sieve effect to separate hydrocarbon isomers such as n-butane and i-butane, n-pentane, l-pentane, and neopentane.

It can be used for fractional purification of mixed hydrocarbon gases such as cyclohexane, fractional purification of hydrogen gas, separation of nitrogen and acid systems in the air by pressure swing blue killing, etc.

Hereinafter, the present invention will be specifically explained with reference to Examples.

Example 1 Degree of polymerization 1700. After dispersing 700y of saponified polyvinyl alcohol (PVA) of 599Φ in water and dissolving it by heating,
Potato? '9 2509 was added and heated to dissolve while beating the mixture. Cool this to room temperature, 37 times! % formalin 900y, 50 heavy fN, and Φ sulfuric acid 2002 were added, and an appropriate amount of water was added to make the total amount of the combined solution 10/P.

Pour this mixture into a 300 x 300 square mold, and
A polyvinyl formal porous body having a mesh-like surface was obtained by carrying out a 11W cross reaction in water at 0°C for 3 days and then washing with water.
Water-soluble resol pine resin (11 Wa Union synthetic ■ product, BRL-28
54) and dried at 80° C. for 24 hours to form a phenolic resin layer of 20% by weight as shown in Table 1.

A synthetic resin-filled porous material containing 50% by weight and 75% by weight was obtained.

The synthetic resin porous body was placed in an RW air furnace and heated for 2 hours in a nitrogen atmosphere.
The mixture was heated to 00°C at 100'C/hr, then turbidly heated at 50°C/hr, and carbonized at 660°C. Some of the samples were activated for a predetermined time in a steam atmosphere at 660°C for carbonization recrossing.

Characteristics of the obtained carbonized products and activated products 1" [Table 51] The pore size distribution and pore volume of each sample were determined from crosstalk such as nitrogen gas adsorption. The smaller the pore diameter, the higher the accuracy of the Kelvin equation. Kelvi decreases, but up to a pore diameter of 1° Ao.
By applying the n formula, the 8 Osaki of the pore size distribution is I
It was determined whether it was below OA'.

Sample layer 1 had weak 'J and jj degrees, exhibited non-uniform deformation, and was not suitable for practical use.

Next, using Sample &4 and Rin 5, butane isomer (n-butane, minimum molecular diameter 4.3 A' purity 99
．． 8%, i-butane, minimum molecular diameter5. OA' pure 7m:
99.0%) of Inkan Hirayama and adsorption fraction, experiments were conducted.

In the adsorption experiment, an adsorption tower of a flow-through adsorption device T was filled with 24 samples x 70 flL, nitrogen gas was used as a carrier gas, n-butane was 5vol%, and i-butane was 5vol%.
A mixed gas consisting of a,
degree (C) and inlet gas concentration (C.

) ratio C,/Co was determined and a breakthrough curve was created. Gas chromatograph (FID detector, column, simalite-squalane 2
5%) was used.

Figure 1 shows the relationship between butane 9% and equilibrium adsorption amount, and Table 2 shows the results for two-component adsorption cutting shears.

As can be seen from FIG. 1, in both samples A4 and A'5, the equilibrium adsorption amount of n-butane greatly exceeded the equilibrium adsorption amount of 1-butane. Especially in case 4, 1-butane was not adsorbed at all.

Also, as shown in Figure 2, sample size 4. ni5 and i-
It was possible to completely adsorb and separate butane and n-butane.

Comparative Example 1 A synthetic resin composite porous body made in the same manner as in Example 1 and consisting of polyvinyl formal polar resin 25-electrode type Φ and phenolic resin 75% by weight was heated at 200'C/hr in a nitrogen atmosphere for 90 minutes.
The temperature was raised to 00°C and activated for 20 minutes in a steam atmosphere.

The weight reduction due to O activation of the obtained activated product was 27% by weight, the apparent richness was 0.2649/cd, the porosity was 84%, the average pore diameter was 50 μm, the specific surface area was 1042nf/P,
The maximum value of the pore size distribution of micropores is a diameter of 18A0. The pore volume for pore diameters of 15 to 200 A' was 0.14-/y.

Using an activated product prepared in the same manner as in Example 1 above, adsorption equilibrium and adsorption separation of butane isomers were carried out in the same manner as in Example 1. The results are shown in Figure 1 and the equilibrium adsorption amount of i-butane is both large and the sample yield is 4. 1- as opposed to 5-5
The equilibrium adsorption amount of butane was slightly larger than the equilibrium adsorption amount of n-butane.

In addition, as shown in Figures 1 and 2, it was not possible to beat n-butane and 1-butane by adsorption amount using material A.

Example 2 Degree of polymerization 1,000. After heating and dissolving 500y of polyvinyl alcohol (PVA) with a degree of phosphorization of 99% in water,
Add small i powder starch 3002 (C1 and heat dissolve with stirring. After cooling it to room temperature, add water-soluble 71-nol resin (C1).
Showa Union Synthetic ■Products.

8002 and reactive bell-shaped phenol resin (Kanebo V (Tan) product, Bell Pearl S-9:10) manufactured according to JP-A-57-177011 Sa. .Average particle 42Q pm) x2
oopz was added, and further 37% Polmarine 900, 300 F of maleic acid which had been pre-blended in water, and an appropriate amount of water were added to adjust the liquid volume to 10 R, and the mixture was stirred thoroughly. 1-1~ was cast into a 300 x 3 Q Omm square mold, and after a curing reaction was carried out in warm water at 60°C for 18 hours, it was washed with water to form a mold with intercalated macropores up to the omitaceous core. A synthetic resin composite porous body was obtained.

The composite sheet yIE composite porous body was placed in a 5Et air furnace, and the temperature was raised to 630° C. at 100′ c/br under a nitrogen atmosphere to carbonize it, followed by activation at 630° C. for 50 minutes under a steam atmosphere. The obtained activated product has an apparent density of 0.365
Y/cd, porosity 77%, average hole diameter 357t
m, the ratio was 537 nt/f, jl+i', and the weight loss due to activation was 86% of that of the carbonized product.

In addition, the maximum value of the pore size distribution of the micropores of the activated product is Io,
The X diameter was 10 A0 or more, and the pore volume in the range of pore diameters from 15 to 200 A0 was 0.032 ci/y.

Next, using the above sample, it was heated to the same temperature as the actual σi, and the temperature was 20°C.
pentane) 4-note (1-pentane, M small molecule:
Diameter 4.9A', purity 99.5%, neo-dry.

Minimum molecular diameter 6.2A0. Adsorption equilibrium and adsorption fraction (purity 99.1%)! [The results of the experiment are shown in Figures 3 and 4.

'Jj3 I': From i to the next step, in the above ice sample, the equilibrium adsorption of 1-pentane J- or the equilibrium absorption of neopenkun was greatly -L, and the adsorption of Figure 4. As a result of the test, a large left side was generated at 1j41 at the time of breakthrough of l-penkun and neopenta/ in the -hi8[: sample.
Both substances were able to be completely separated by adsorption.

Comparative Example 2 Same as Example 2 (ζ- produced synthetic tree IlO?J-
Put the combined porous body into the electric furnace (200 in 1).
℃/hr-Ascend to C850c iL' Shitasa, Mizuchoki 6
I spent an hour in the dark atmosphere. The M active items that were stolen are
0.283F/d, porosity 83%, macropore average diameter 4
0 cape, a specific surface area of 1490 nt/9', and an addition of γ1, the weight loss was 52% of that of the carbonized product.

In addition, the maximum pore size distribution of the micropores of the activated product is 1°il'
(Diameter 21 AoC: Yes, +ia hole Naonaka 15-20
The pore volume in the 0A0 range was 0.19 d/gJ.

As in Example 2, adsorption equilibrium and adsorption separation experiments of pentane isomers using one or more activated products were conducted. The result is the third
The results of Example 2 are also shown in FIG.

As can be seen from these results, in this sample, the difference in equilibrium adsorption between l-pentane and neopentane was extremely small, making it impossible to adsorb and separate the two.

Ta.

Example 3 Degree of polymerization 500. Add an appropriate amount of water to polyvinyl alcohol 6002 with a saponification degree of 99%, heat and dissolve, and then water-soluble phenol resin (Showa Union Synthesis ■ product).

BRL-2854) as solid content is 4ooy.

After drying and curing this mixture of 37% by weight formalin 900F and paratoluene at 80°C for 24 hours, it was further cured at 120°C for 2 hours.
After curing for a time, it was pulverized, and a 31111n×4 mL granular molded product was created using the water-soluble phenol resin described above as a binder. The ratio of polyvinyl alcohol and phenol resin in the molded article was 55:45.

This granular molded product was placed in an electric furnace at 30°C under a nitrogen atmosphere.
After carbonizing by raising the temperature to 600° C./hr, the mixture was further heated in a steam atmosphere for 60 minutes. The obtained activated product had an apparent density of 0.417 Y/cd and a specific surface area of 598 n? /
9, the decrease in heavy ffi due to activation is 7.4 heavy 41 for carbonized products.
%Met.

Further, the maximum value of the pore size distribution of the micropores of the activated product was 10 A0 or less in diameter, and the volume of 3 pores in the pore diameter range of 15 to 200 A' was 0.025 c//y.

Next, using the above sample, dichloromethane (minimum molecular diameter 3.8A0. pure, modified 99.6 form) and n-hebutane (minimum molecular diameter 4.9A') were prepared in the same manner as in Example 1 at 20°C.
, purity 99.4%). As a result, n-hebutane, which has an extremely small amount of adsorption, breaks through first,
I was able to heat it completely with dichloromethane.

Comparative Example 3 Using the same strainer as in Example 3, a water-soluble phenol resin (Showa Union Synthetic Product, BRI, -2854) was hardened and pulverized, and further granulated to form a 31 x 4'mL granular molded product. Created. The molded product was placed in a 11 atmosphere diameter, and carbonized and activated under the same conditions as in Example 3. The obtained activated product has an apparent density of 0.461! /l*, specific surface area 216 ml/f
/ The weight loss due to activation was 51% by weight of the carbonized product. In addition, the maximum value of the pore size distribution of the micropores of the activated product is
The diameter was 13 A0, and the pore volume in the range of pore diameters 15 to 200 A6 was 0.1.1 cd/9'.

Using the above test v1, cyclomethane and n-
An adsorption separation experiment of hebutane was conducted, but it was not possible to separate the two.

[Brief explanation of the drawing]

Figure 1 Adsorption etc. of n-butane 11-butane Figure 2
Figure 3 Adsorption separation experiment results for n-butane and 1-butane. i- Adsorption, etc. confusion for pentane and neopentane Figure 4. 1- Adsorption separation experiment results for pentane and neopentane 'r;-in': Applicant Kaburabo Co., Ltd,!・2. ? . Figure 1 1) 2 Figure 3

Claims (2)

[Claims] (1) 10 to 70% by weight of polyvinyl alcohol resin
, a synthetic resin composite consisting of 30 to 90% by weight of phenolic resin is carbonized in a non-oxidizing atmosphere at a temperature range of 500 to 700°C, or after carbonization, further under an oxidizing atmosphere,
Pore diameter 10A, activated in a temperature range of 500 to 700°C in a range where the weight of carbide is reduced within 15% by weight.
The maximum value of the pore size distribution is in the region below 1°, and the pore diameter is 1
Pore volume in the range of 5-200A° is 0.1cm^3/g
The molecular sieve is carbon. (2) Molecular sieve carbon has an apparent density of 0.1 to 0.8 g/
cm^3, porosity 50-95%, diameter 1-500μm
The molecular sieve carbon according to claim 1, which has continuous macropores having a network structure.