JPS6253725A - Permselective membrane for sulfurous acid gas - Google Patents

Abstract

PURPOSE:To obtain permselective membranes employable for the separation of sulfurous acid gas from mixed gases, purification, and condensation by using derivatives of cellulose having degree of substitution over 0.05 on the basis of alkylsulfinylethyl radicals. CONSTITUTION:By the reaction between alkylvinylsulfoxide and cellulose in the presence of alkali catalyst, alkylsulfinylethyl cellulose is obtained. The preferable conditions of reaction are: concentrations of alkali catalyst in aqueous solution in the range of 5-40% and temperatures 10-50 deg.C. Reaction is carried out in such a manner that 0.1-50mol of alkylvinylsulfoxide per mole of glucose in cellulose is added so that average degree of substitution becomes over 0.05. Alkylsulfinylethyl cellulose obtained is dissolved in proper solvent, whereby membranes are produced. When average degree of substitution is over 0.6, membranes can be made using water as solvent.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a sulfur dioxide gas selectively permeable membrane.

[Conventional technology]

Conventionally, a polyacecool resin film has been known as a sulfur dioxide gas selective permeation membrane (Japanese Patent Laid-Open No. 57-207504
(No. Publication) [Problems to be solved by the invention] However, the Vo-Secure resin used in the above film has a high degree of crystallinity, so it has poor processability and is difficult to form into a thin film, and the resulting film is difficult to produce in the presence of sulfur dioxide gas. The problem is that the permeability is insufficient, making it impractical as a selectively permeable membrane for sulfur dioxide gas.

[Means for solving problems]

The present invention solves the above-mentioned problems, and provides that in formula c, a plurality of X's may be the same or different, and are hydrogen atoms or formula (■): (wherein, R has 1 to 6 carbon atoms. an alkyl sulfinylethyl group represented by (indicating an alkyl group of is an integer] A sulfur dioxide gas selectively permeable membrane made of alkylsulfinylethyl cellulose represented by the following is provided.

The alkylsulfinylethylcellulose of general formula (1) used in the present invention is a novel cellulose derivative.

The alkylsulfinylethyl cellulose has a
In the alkylsulfinylethyl group of formula (II),
R represents an alkyl group having 1 to 6 carbon atoms, such as methyl, ethyl, propyl, butyl, pentyl and hexyl.

As used herein, the average degree of substitution of alkylsulfinylethyl cellulose with alkylsulfinylethyl groups of general formula (n) refers to the average degree of substitution of alkylsulfinylethyl groups present per glucose unit (i.e., anhydroglucose ring) of the cellulose derivative. It means the number of pieces.

In the present invention, the average degree of substitution by the alkylsulfinylethyl group of general formula (II) is at least 0.05, preferably at least 0.6. When the average degree of substitution is less than 0.05, the sulfur dioxide permselectivity is insufficient, and when it is 0.6 or more, the alkylsulfinylethyl cellulose of the present invention becomes water-soluble and can be easily converted from an aqueous solution by a casting method. It has the advantage of being able to be formed into a film.

The alkylsulfinylethyl cellulose of the present invention has cellulose and the general formula (■): RS CH=CI(z (I
It can be produced by reacting an alkyl vinyl sulfoxide represented by I)↓ (wherein R is the same as in general formula (II)) in the presence of an alkali catalyst.

The cellulose used is not particularly limited, and for example, natural cellulose such as cotton linters, chemical wood pulp, various regenerated celluloses, crystalline cellulose, etc. can be used.

Further, the alkyl vinyl sulfoxide used in the above production method can be synthesized, for example, through a reaction process represented by the following formula.

RSH+(, HsONa −”R5Na + CJso
llRSNa + CI C) 12cH20H-R5C
112CH2011+ NaC1 [wherein R is the general formula (
Same as n)] That is, hydroxyethyl alkyl sulfide is synthesized by reacting ethylene chlorohydrin with sodium thiolate obtained by reacting an alkyl mercaptan with sodium ethoxide in ethanol at room temperature. Next, this hydroxyethyl alkyl sulfide was subjected to a dehydration reaction in an aqueous potassium hydroxide solution at 250°C to form vinylargyl sulfide, which was then oxidized in an aqueous sodium metaperiodate solution at 0°C to form an alkyl vinyl sulfoxide. Can be synthesized.

Further, examples of the alkali catalyst used in the above production method include sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, etc., but sodium hydroxide is usually economically advantageous.

The above production method is carried out by reacting -i with both reaction components under stirring at 10 to 50°C (usually room temperature is sufficient) in an aqueous solution containing an alkali catalyst at a concentration of 5 to 40%. . Generally, 0.1 to 5 alkyl vinyl sulfoxides are added per mole of glucose units in cellulose.
The reaction is carried out to obtain sulfinylethylcellulose having a degree of substitution of 0 mole and a desired degree of substitution. After the reaction is completed, the reaction mixture is neutralized with acetic acid, etc., and then poured into a mixed solvent of acetone/methanol to precipitate the product, and the precipitated product is redissolved in water, followed by acetone/methanol, - It can be purified by re-precipitation.

The alkylsulfinylethylcellulose thus obtained is a novel cellulose derivative having the following spectroscopic characteristics.

That is, when the cellulose derivative is dissolved in heavy water and subjected to proton nuclear magnetic resonance spectroscopy, the absorption of protons associated with the hydroxyl group of cellulose decreases, and the absorption of protons of the alkyl group of alkyl vinyl sulfoxide decreases to 3.
1 ppm, and no proton signal of the vinyl group of alkyl vinyl sulfoxide is observed. The above facts indicate that alkylsulfinylethyl cellulose into which an alkylsulfinylethyl group has been introduced is obtained by addition reaction of the hydroxyl group of cellulose with the vinyl group of alkyl vinyl sulfoxide. Furthermore, alkylsulfinylethyl cellulose has the following absorption properties.

' HNMR (DzO) δ9pm: 4.0-4.2 (m
, -OCH, CHzSR).

↓ 3.4 to 3.7 (m, -0CR2GHzSR).

In order to obtain the sulfur dioxide gas selectively permeable membrane of the present invention by forming a film from the alkylsulfinylethyl cellulose produced as described above, a solution dissolved in an appropriate solvent is cast onto a smooth surface, etc., or onto a porous substrate. After forming a coating film by coating or other methods, the solvent is dried and removed. Examples of the solvent used include dimethyl sulfoxide, acetone, water, etc., and water can be preferably used when the average degree of substitution is 0.6 or more.

〔Example〕

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

Example 1 100ml of 20% sodium hydroxide aqueous solution! Inside is crystalline cellulose (trade name: Avicel PHIOI).

After adding 5.0 g of Asahi Kasei Corporation), methylvinyl sulfoxide was added in an amount giving a molar ratio of 9.0 to the glucose units of cellulose, and the mixture was stirred at room temperature. After reacting for 9 hours, the reaction mixture was diluted with acetic acid. It was peaceful. This was poured into an acetone/methanol mixed solvent (7/3 volume ratio) to precipitate the reaction product. The product was purified by repeating the operation of dissolving it in water and reprecipitating it again with an acetone/methanol mixed solvent (volume ratio 7/3). The sulfur content of the obtained methylsulfinylethyl cellulose was measured by elemental analysis, and the average degree of substitution by methylsulfinylethyl groups was determined.

The resulting 15% by weight aqueous solution of methylsulfinylethyl cellulose was cast onto a smooth glass plate and dried to produce a film with a thickness of 81 μm. The gas permeability coefficient (P) of this film for oxygen gas, nitrogen gas, carbon dioxide gas, and sulfur dioxide gas under 2 atmospheres was calculated using the volumetric method (S
, A., 5tern, J.

^pp1. Polym, Sci, 7.203
5 (1963)) to determine the permeability coefficient ratio of sulfur dioxide gas to other gases.

The above results are shown in Table 1.

Example 2 Ethylsulfinyl ethyl cellulose was produced in the same manner as in Example 1, except that ethyl vinyl sulfoxide was used instead of methyl vinyl sulfoxide and 10% aqueous sodium hydroxide solution was used instead of 20% aqueous sodium hydroxide solution. It was molded into a 90 μm film. Example 1
Sulfur content, average degree of substitution, and gas permeability were measured in the same manner as above.

The results are shown in Table 1.

Example 3 After adding 5.0 g of powdered Wood Bulb to 200 m6 of a 20% aqueous sodium hydroxide solution, n-propyl vinyl sulfoxide was added in an amount to give a molar ratio of 9.0 to the glucose units of cellulose, and the mixture was reacted at room temperature for 9 hours. Afterwards, the reaction mixture was neutralized with acetic acid. The subsequent purification was carried out in the same manner as in Example 1. The sulfur content of the obtained n-propylsulfinylethyl cellulose, the average degree of substitution by n-propylsulfinylethyl groups, and the gas permeability of a film formed to a thickness of 100 μm were measured. The results are shown in Table 1.

Example 4 T-butyl sulfinyl ethyl cellulose was produced in the same manner as in Example 3, except that 1-butyl vinyl sulfoxide was used instead of n-propyl vinyl sulfoxide. The sulfur content, average degree of substitution, and gas permeability of a film formed to a thickness of 90 μm of the obtained L-butylsulfinylethylcellulose were measured in the same manner as in Example 1. The results are shown in Table 1.

Example 5 N-hexylsulfinyl ethyl cellulose was produced in the same manner as in Example 3, except that n-hexylvinyl sulfoxide was used instead of n-propyl vinyl sulfoxide. The sulfur content, average degree of substitution, and gas permeability of a film formed to a thickness of 85 μm of the obtained n-hexylsulfinylethylcellulose were measured in the same manner as in Example 1.

The results are shown in Table 1.

Comparative Example 1 A film with a thickness of 127 μm was formed from commercially available ethyl cellulose (manufactured by Hanui Kagaku, average degree of substitution by ethyl group 2.5, viscosity 80-120 cps), and gas permeability was measured in the same manner as in Example 1. . The results are shown in Table 1.

Example 6 Example 1 except that the amount of methyl vinyl sulfoxide used was changed to an amount such that the molar ratio to the glucose units of cellulose was 27.4, and the reaction time was changed to 9 hours.
Methylsulfinylethylcellulose was produced and purified in the same manner as above. The sulfur content and average degree of substitution by methylsulfinylethyl groups of the obtained methylsulfinylethyl cellulose were measured in the same manner as in Example 1, and the sulfur content was 114.15% by weight and the average degree of substitution was 1.18.

Furthermore, the 'H-NMR spectrum and the 'C-NM)? spectrum of the obtained methylsulfinylethyl cellulose were measured, and the following results were obtained.

' H-NMR (020) δ; 3.10 (s, (j)), 3.47-3.60 (
m, (i)).

3.75 (m, (e)), 4.02-4.07 (m,
(h)).

4.05-4.10(m, (f)), 4.25(
m, (c)).

4.35 (m, (b)), 4.55 (m, (d)
).

4.55 (m, (a)), 4.80s, (g))
.

■ ■ ↓■ [Effects of the Invention] The sulfur dioxide gas selective permeation membrane of the present invention has extremely high selective permeability for sulfur dioxide gas, and can be used to separate and purify sulfur dioxide gas from a mixed gas such as air, or to purify sulfur dioxide gas in a mixed gas. Specifically, it is useful in, for example, the removal of toxic sulfur dioxide gas from exhaust gas, environmental protection such as purification of raw material gas for synthesis, and industrial production.

Claims (1)

[Claims] 1) General formula (I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(I) II): An alkylsulfinylethyl group represented by RSCH_2CH_2-(II) (wherein R represents an alkyl group having 1 to 6 carbon atoms), and an alkylsulfinylethyl group of general formula (II) per glucose unit. wherein the average degree of substitution is at least 0.05, and n is an integer representing the number of repeating glucose units. 2) The sulfur dioxide gas selective permeation membrane according to claim 1, wherein the average degree of substitution of alkylsulfinylethyl cellulose by alkylsulfinylethyl groups is at least 0.6.