JPH01176403A - Separation of organic solvent - Google Patents

Abstract

PURPOSE:To practically separate the mixture of chlorine substitution products of hydrocarbon and fluorine/chlorine substitution products of hydrocarbon by utilizing a membrane consisting of polysulfone and performing osmotic gasification separation. CONSTITUTION:An amorphous nonporous separation membrane consisting of aromatic polysulfone shown by a formula I is utilized. In an osmotic gasification apparatus equipped with this membrane, the liquid mixture of an organic solvent such as mixed liquid of tetrachloroethylene/1,1,2-trichloro-1,2,2-trifluoroethane is fed to the primary side of the membrane and the secondary side is decompressed and sucked. Thereby substance low in molecular weight incorporated in the mixture is gasified to permeate the separation membrane and is transferred to the secondary side. This transferred gas is cooled, condensed and liquefied. In such a way, the organic liquid solvent having low molecular weight is separated from the organic liquid solvent having high molecular weight.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for separating a liquid mixture of organic solvents, and particularly to a method for separating a liquid mixture of a chlorinated hydrocarbon and a fluorine/chlorinated hydrocarbon. This invention relates to a method for separating by pervaporation. These chlorinated hydrocarbons and fluorine/chlorine substituted hydrocarbons are widely used as dry cleaning solvents and as cleaning solvents for precision machinery and precision electronic parts. It is suitable for use in solvent recovery equipment.

[Conventional technology]

Distillation has traditionally been used as a method for separating liquid mixtures of organic solvents. However, the distillation method consumes a lot of energy, and in particular, in the case of azeotropic mixtures, precision distillation is required.Recently, separation by pervaporation (separation by pervaporation) has been considered as an energy-saving separation method.

The pervaporation method is a method in which an organic liquid mixture is supplied to the primary side across a separation wall, and the pressure of the secondary side is reduced to condense and separate the permeated vapor. Therefore, components with high affinity for the separation model selectively permeate and are separated.

Separation by pervaporation methods that have been studied so far are mainly based on
The main focus is on the separation of water-organic liquid mixtures, especially water-ethanol systems. An example of separating a liquid mixture of organic solvents by pervaporation is cyclohexane-benzene separation (see JP-A-55-48205 and JP-A-62-49903).

[Problem that the invention seeks to solve]

In the pervaporation methods proposed so far, the separation coefficient of the separation fusuma is small and several separations are required to perform high concentration concentration separation, so they cannot be said to be advantageous compared to distillation methods. There wasn't.

In addition, the permeability coefficient for separation is small, and when a large amount of liquid mixture is to be treated, the membrane area required is enormous, making this method impractical.

Furthermore, the above-mentioned cyclohexane-benzene separation as an example of separation of a liquid mixture of organic solvents by pervaporation method is as follows:
There are problems with separation performance and permeation performance, and it has not been put into practical use.

In addition, chlorine-substituted hydrocarbons and fluorine-substituted hydrocarbons
There are no examples of separation of mixtures with chlorinated compounds.

The present invention proposes a practical method for separating organic solvent liquid mixtures, particularly mixtures of the above-mentioned chlorinated hydrocarbons and fluorine/chlorinated hydrocarbons, by pervaporation.

[Means for solving problems]

The present invention was made based on the knowledge that a separation probe made of aromatic poly-N-phone exhibits high permeability while maintaining high separation performance.

That is, the present invention uses a microphone consisting of a polyphone to
The present invention relates to an organic solvent separation method characterized by pervaporative separation of an organic solvent liquid mixture.

The separation in the method of the present invention is based on the general formula CH3Q This is an aromatic polyphone shown by

This aromatic poly-N phone is made of amorphous and non-porous thermoplastic resin, and has excellent heat resistance, creep resistance, dimensional accuracy, hot water resistance, flame retardancy, and electrical properties. It is widely used in the electrical and electronic fields (printed circuit boards, connectors, etc.), the hot water field (steam valves, insulation materials for anti-corrosion electrodes, etc.), medical care, food industry, automobile parts, etc.

Note that the above-mentioned non-porous means that there are no pores other than the molecular gaps generated by thermal vibration of the polymer that makes up the membrane, and the molecular gaps are approximately 10λ or less in diameter. moves.

In addition, it can be used as an ultrafiltration membrane in the medical and food industry fields such as polysulfone, gas separation, blood purification, fruit juice concentration, cheese whey processing, yogurt production, and pure water production. However, the membrane permeation mechanism is different from the above-mentioned amorphous and non-porous membranes used in the method of the present invention.

In other words, with porous membranes such as ultrafiltration membranes and dialysis membranes, separation is performed based on the difference (physical factor) between the size of the low molecules that permeate the membrane and the size of the pores. The amorphous/non-porous materials used in this method have small pores (molecular gaps) through which small molecules can pass through, as mentioned above, so the chemical affinity and electrical Separation takes place under the influence of physicochemical factors. Therefore, the permeation mechanism is different between the currently commercially available ultrafiltration membrane made of polysulfone and the aromatic polysulfone membrane used in the method of the present invention.

Organic solvent liquid mixtures that can be separated by the method of the present invention include mixtures of chlorinated hydrocarbons and fluorine/chlorinated hydrocarbons; in addition to these, chlorinated hydrocarbons; Examples include mixtures with methanol, ethanol-μ, ethylene glycol, propane-1,2-diol, n-butanol, hebutane, and the like.

[Effect]

In the method of the present invention, an organic solvent liquid mixture is supplied to the primary side across a polysulfone separation membrane, and the pressure is reduced on the secondary side.

Then, those with low molecular weights in this organic solvent liquid mixture are vaporized, transmit the above amount of mW, and migrate to the secondary side.

The gas transferred to the secondary side is condensed and liquefied. In this way, the low molecular weight organic solvent liquid and the high molecular weight organic solvent liquid are separated.

The degree of pressure reduction on the secondary side is largely determined by the condensation temperature of the solvent vapor that has permeated into the secondary side, so the optimum pressure change is determined in actual operation, but in general, it is Generally, it is preferable to reduce the pressure in the range of about 1 to 500 mHt.

〔Example〕

In an example, a polymer solution prepared by dissolving 10 parts by weight of polysulfone having the above general formula with n of 50° to 80 in 90 parts of dimethyl μformamide was cast onto a glass plate to a thickness of 500 μm.
After drying for 1 hour at 80″C, a homogeneous transparent film of ILO μm was obtained.

A pervaporation device (effective simulated area 27, Oe
x;') with tetrachlorethylene/LL2-)dichloro-L2.2-)lifluoroethane (so/s.

(weight ratio) mixed solution was supplied, and the permeate side was vacuumed to 1.0 mHf. After cooling and condensing the vapor that passed through the filtrate, the amount of permeation and the components of the permeate were analyzed.

The permeation rate is t46×10 t/- format % formula %()
) were 2 & 5. At this time, 50% by weight of tetrachlorethylene could be concentrated and separated to 9&4% by weight.

Example λ A polymer solution prepared by dissolving 3 parts by weight of the same polyyphon as in Example 1 in 9 parts by weight of dimethylformamide was cast onto a glass plate to a thickness of 500 μm, and after drying at 80° C. for 1 hour, A homogeneous transparent layer with a cL of 5 μm was obtained.

When a separation test was conducted in the same manner as in Example 1 using this solution, the permeation rate was t 6 × 10 t / 511”.
5ec (transmission coefficient is λS X 1 G-” f-ex
/ag”・sec), and the separation coefficient was 2&0. At this time, 150% by weight of tetrachlorethylene could be concentrated and separated to 9&3% by weight.

Example 5 Using the same specifications as in Example 2, a mixture of tetrachlorethylene/1.1.2°2-tetrachloro-12-difluoroethane (50/so weight ratio) was fed to the same pervaporation device as in Example 1. Then, a separation test was conducted in the same manner as in Example 1. However, the permeation rate is 11×10″″ f /esi
fist sec (transparent aim is z b x 1o -10t
The separation coefficient was 190. At this time, 50% by weight of tetrachlorethylene was added to 9
It was possible to concentrate and separate the product to 50% by weight.

EXAMPLE Using the same membrane as in Example 2, tetrachlorethylene/12-dichloro-tt2.
When a 2-tetrafluoroethane (50,150 weight ratio) mixed solution was supplied and a separation test was conducted in the same manner as in Example 1,
The permeation rate is 4. Ox 10-6t /d @sec (
The transmission coefficient is 2-OX 10-"f-ex/51"
・sec) and the separation coefficient was 315. At this time, 50% by weight of tetrachlorethylene could be concentrated and separated to 97.0% by weight.

Example i Carbon tetrachloride/i,t2-trichloro-1,2,2-
) Difluoroethane (50150 weight ratio) mixed liquid was supplied and a separation test was conducted in the same manner as in Example 1. The permeation rate was 4.8X10 f/1-5ec (permeation coefficient was 2.
4 x 10-''f.ex/lx'.5ec), and the separation coefficient was 21.4.At this time, 50% by weight of carbon tetrachloride could be concentrated and separated into 9!L5% by weight.

Example & Using the same specifications as Example 2, LLt2-tetrachloroethane/t, 1.2- in the same pervaporator as Example 1.
) dichloro-1,2,2-)difluoroethane (50
/so weight ratio) was supplied and a separation test was conducted in the same manner as in Example 1, and the permeation rate was &3
f /ex;'-5ee (transmission coefficient is 2×10
?・ex /aJ・ki) and the separation coefficient was 1S, 7. At this time, 50% by weight of 11°1.2-tetrachloroethane could be concentrated and separated to 940% by weight.

Example 1 Lt,2,2-te)sachloroethane/212-trichloro-1,2,2-)lifluoroethane (50750
When the mixture (weight ratio) was supplied and a separation test was conducted in the same manner as in Example 1, the permeation rate was &2 x 10-'?
151”・Formula (transmission coefficient is 51×10 t-es/e
x”·sec), and the separation coefficient was 159.

At this time, tl of 50% by weight.

2.2-Tetrachloroethane could be concentrated and separated to 3% by weight of 9S.

Example & Using the same membrane as Example 2, 1.1.1-)lichloroethane/1°tl-trichloro-tl, 2-)lifluoroethane (50150 weight ratio) in the same pervaporation apparatus as Example 1. ) When the mixed solution was supplied and a separation test was conducted in the same manner as in Example 1, what was the permeation rate? , 7X 10-6f151+
2-5ec<transmission coefficient is 4.9×10-” f-country/i
・Ki), and the separation coefficient was jO. At this time, 5
0% by weight of 1. i, 1-) Lichloroethane to 9[L
Only 0 weight % Kl reduction was possible.

Example j Using the same specifications as in Example 2 and in the same pervaporation apparatus as in Example 1, i, 1.2-)lichloroethane/'1゜tl-trichloro-1,z2-)lifluoroethane (50150
When the mixed liquid (weight ratio) was supplied and a separation test was conducted in the same manner as in Example 1, the permeation rate was 9.4 x 10''''6t1
5g2@5ec (permeability coefficient is t7X10-10t -e
x / aw” ・Formula)tonashi, minute i section lf&ha 9.2
It became. At this time, 50% by weight of t1.2-)lichloroethane could be condensed and separated into 2% by weight of 9CL.

〔Effect of the invention〕

As described above, according to the method of the present invention, a liquid mixture of chlorine-substituted hydrocarbons and fluorine- and chlorine-substituted hydrocarbons can be separated by four condensations at a high concentration, and the concentration used in the method of the present invention is unit Since the amount of permeation per area is large, the method of the present invention
! This is extremely effective in making the separation module more compact and saving energy in the separation process.

Claims (2)

[Claims] (1) An organic solvent separation method characterized by permeating and vaporizing an organic solvent liquid mixture using a membrane made of polysulfone. (2) An organic solvent separation method according to claim 1 using a membrane made of polysulfone represented by the general formula ▲ Numerical formula, chemical formula, table, etc. ▼. (3) The organic solvent separation method according to claim 1 or 2, wherein the organic solvent liquid mixture is a liquid mixture of chlorinated hydrocarbons and fluorine/chlorine substituted hydrocarbons.