KR100538544B1 - Facilitated transport membranes containing zwitterionic silver complexes for the separation of olefin/paraffin mixtures and its preparation method - Google Patents

Abstract

The present invention relates to an accelerated transport separation membrane for separation of olefins / paraffins based on zwitterionic silver compounds. Promoted transport membrane of the present invention for separating an olefin or diene hydrocarbon from a paraffinic hydrocarbon is a solution in which a zwitter ionic silver compound capable of reversibly forming a complex with an olefin or diene alone or mixed with a polymer Is prepared by coating on a porous support. Since silver ions present in the facilitated transport membrane are strongly bound to sulfonate (SO ₃ ) groups and are rarely reduced by impurities or light, the stability of the membrane can be greatly improved. It has high permeability and selectivity, and shows long lasting initial activity even in long time driving conditions.

Description

Zwitterionic silver compound-promoted transport membrane for separation of olefins / paraffins and its manufacturing method

Olefin, one of the basic raw materials of the chemical industry, is mainly obtained by cracking naphtha or natural gas. In this process, paraffinic hydrocarbons having similar boiling points are produced together, and thus must be separated and purified.

The mixture of olefins and paraffins is mainly separated by low temperature distillation, but because of the high equipment cost and energy consumption, adsorption and membrane separation processes of low energy consumption have attracted attention.

Ind. Eng. Chem. Res. 2571 (1998) discloses a method for separating olefins and paraffins by adsorption using silver salts or copper compound solutions that reversibly react with olefins, but this method requires a large apparatus because it has to undergo desorption after adsorption. There are disadvantages that must be made.

Membrane separation method has been mainly applied to the separation of carbon dioxide and methane, oxygen and air, and organic vapor and air, but the research to apply it to the separation of olefin and paraffin has been actively conducted recently with the introduction of the promotion transport concept. The term 'promoting pine' is used to improve the olefin separation ability of the membrane by adding a compound capable of selectively and reversibly reacting with the olefin to the membrane, such as a liquid membrane, an ion exchange resin membrane, and a polymer membrane.

US Patent No. 3,758,603 discloses a method of using a supported or fixed liquid membrane made by supporting silver salt on a separator having micropores. However, this has the disadvantage that it is difficult to maintain the separation efficiency for a long time because the accelerated transport salt is lost by the gas introduced and the solvent is easily volatilized. As disclosed in US Pat. No. 4,318,714, even in the case of using an ion exchange resin membrane in which cations are substituted with silver to prevent the loss of silver ions, as in the case of using a fixed liquid membrane, the accelerated transport occurs only in the presence of moisture. Has to be maintained at a constant level, and after separation it is necessary to remove the moisture again. In addition, the separation membrane is not practical because it must be thicker than 100 ~ 500㎛ and separation efficiency is also low.

U.S. Patent No. 5,670,051 discloses a promotion transport polymer membrane comprising a silver salt in a polymer. That is, the silver salt, which is a promoter for transport, is not simply mixed or diffused in the polymer, but exists in an ionic state dissociated by chemically bonding to a functional group of the polymer. According to this, since separation of olefin and paraffin is performed in the absence of moisture, the loss of silver salt by an introduction gas does not generate | occur | produce, and the thickness of a separator can be manufactured to several micrometers or less, and gas permeability can be remarkably improved. In addition, much higher concentrations of silver salts can be used than other membranes reported so far, which can dramatically increase the separation efficiency of olefins.

However, the polymer membrane containing the silver salt tends to be easily reduced by light or impurities as gas permeation proceeds, so that the separation performance is sharply degraded when used for a long time, making it difficult to use.

Therefore, the object of the present invention is not only to reduce the performance of the membrane even after a long time operation, but also to promote the separation of olefin / paraffin of a new concept that can be produced much simpler and cheaper than conventional sulfonate group-containing ion exchange resin (ionomer) membrane To provide a transport membrane.

Still another object of the present invention is to provide a method for preparing the above-mentioned promoting transport separation membrane for olefin / paraffin separation.

The olefin carrier of the promoted transport separation membrane for separation of olefins / paraffins according to the present invention is a zwitterionic silver compound of formula (1).

In Formula 1, R is an alkyl or phenyl group having 1 to 8 carbon atoms, n is 2 or 3, X ⁻ is an anion selected from BF ₄ , NO ₃ , ClO ₄ , CF ₃ SO ₃ , PF ₆ , and SbF ₆ .

Promoted transport membrane for separation of olefin / paraffin according to the present invention

     (a) dissolving the zwitter ionic silver compound of Formula 1 in a solvent to obtain a solution in which the zwitter ionic silver compound is dissolved;

(b) coating the solution obtained in step (a) on a support or glass plate;

(c) obtained by a method comprising the step of drying the support or the glass plate of step (b) in a state in which light and oxygen are blocked.

The solvent used in step (a) may be used to dissolve the zwitter ionic silver compound and to be completely removed in the drying step after coating on the support, for example, water or alcohol having 1 to 4 carbon atoms. The solvent and the zwitterionic silver compound are used in a weight ratio of 10: 1 to 1: 1. If the ratio exceeds 10: 1, the thickness of the membrane becomes too thin, which may cause the membrane to leak. If the ratio is less than 1: 1, the membrane becomes too thick and poor in permeation.

In addition, in order to increase the strength of the separator containing the zwitter ionic silver compound may be further included a polymer material. In this case, it is preferable to use a polymer that is well dissolved in water or an alcohol capable of dissolving the zwitter ionic silver compound, and the polymer and the zwitter ionic silver compound are dissolved together in a solvent. Examples of such polymers include polyvinylpyrrolidinone (PVP), poly (2-ethyl-2-oxazoline), polyacrylamide, polyethylene oxide or polyvinyl formal, and the like.

In this case, the polymer compound may be used in an amount of 10 to 50 wt.% Based on the weight of the zwitterionic silver compound. When used in the range of 10 to 50 wt.%, It is particularly preferable because it can maintain the separation ability of silver ions with respect to the olefin while maintaining the role of the polymer for maintaining the strength of the membrane.

The support is one that does not dissolve in a solvent, but it is preferable to use one having good micropermeability with micropores in micrometer (μm) units, and examples thereof include a microporous polyester support membrane.

The thickness of the accelerated transport film varies depending on the needs of both the coating on the support and the peeling by coating on the glass plate, but a few μm is generally suitable.

Olefin and paraffin separation using the membrane prepared by the above method can be carried out in the liquid phase or gas phase. Small molecular weight olefin and paraffin mixtures, such as ethene and ethane, propene and propane, and mixtures of 1-butene and butane, can be separated from the gas phase at room temperature by gas phase, but C ₅ or more olefins and paraffins present as liquid at room temperature. In the case of mixtures, the liquid or mixture can be separated by vaporization.

The configuration of the present invention will be clearer through the following examples.

Example 1

Zwitterionic silver compounds ( )

A solution of 0.4 g dissolved in 1.6 g of water was coated on a 47 mm diameter support (microporous polyester support membrane, 0.1 μm), dried in nitrogen in a light-blocked oven at room temperature for 12 hours, and then vacuum at 40 ° C. In the state of drying again for 24 hours to prepare a separator.

The membrane thus prepared was mounted in a permeation experiment, and the permeation experiment was performed for 100 hours while maintaining the pressure of the mixed gas of propene and propane mixed at 1: 1 at 2 atm.

The gas permeation rate was measured with a lather flow meter and the resolution of permeated gas, ie the amount of propene permeated to permeate, was analyzed by gas chromatography with TCD and Unibead-2S column.

When the resolution of propene to propane permeation rate and 1 hour after the start of each permeation ^{67X10 -6 ㎤ (STP) / ㎠} · S · ㎝Hg and 120, when the 100 hours 68X10 ^-6 ㎤ (STP) / ㎠ It was measured with S.cmHg and 118.

Example 2-10

Zwitter ionic silver compounds under the same conditions as in Example 1

( Table 1 shows the results of permeation experiments after the separation membrane was prepared using only different types of).

Example Types of Zwitter Ionic Silver Salts Permeability Selection (propene / propane) R n X 1 hours 100 hours 2 CH ₃ 2 BF ₄ 98 97 3 C ₂ H ₅ 2 NO ₃ 131 132 4 nC ₄ H ₉ 2 NO ₃ 113 110 5 nC ₄ H ₉ 3 BF ₄ 88 86 6 CH ₃ 3 ClO ₄ 79 80 7 C ₆ H ₅ 2 CF ₃ SO ₃ 68 68 8 C ₆ H ₅ -CH ₂ 2 PF ₆ 72 70 9 nC ₈ H ₁₇ 2 SbF ₆ 63 60 10 C ₆ H ₅ 3 NO ₃ 66 67

Example 11-15

Table 2 shows the results of permeation experiments using the separator prepared in Example 1 while changing the type of olefin and paraffin mixture.

Example Gas mixture Resolution (olefins / paraffins) 1 hours 100 hours 11 Eten / ethane 147 148 12 1-butene / n-butane 114 113 13 1-pentene / n-pentane 97 96 14 1-hexene / n-hexane 84 80 15 Isoprene / n-pentane 125 125

Example 16-19

Table 3 shows the results of permeation experiments after the separation membranes were prepared using only the type of solvent used instead of water under the same conditions as in Example 1.

Example Type of solvent Resolution (propene / propane) 1 hours 100 hours 16 Methanol 105 105 17 ethanol 93 91 18 Isopropanol 87 88 19 1-butanol 74 73

Example 20-23

Table 4 shows the results of permeation experiments after the separation membrane was prepared by adding 10 wt% of various polymers to the zwitter ionic silver compound under the same conditions as in Example 1.

Example Type of polymer Resolution (propene / propane) 1 hours 50 hours 20 Poly (2-ethyl-2-oxazoline) 115 114 21 Polyethylene oxide 116 113 22 Polyvinylpyrrolidinone 117 117 23 Polyacrylamide 93 90

Example 24-26

In the same conditions as in Example 20, only the amount of poly (2-ethyl-2-oxazoline) (POZ) was changed to prepare a separation membrane, and the results of permeation experiments are shown in Table 5.

Example POZ / zwitterionic salts (wt%) Resolution (propene / propane) 1 hours 100 hours 24 5 118 116 25 20 109 108 26 50 96 96

Comparative Example 1-3

Under the same conditions as in Example 1, a separator was prepared using a polymer (POZ) and a silver salt instead of the zwitter ionic silver compound.

The amount of the silver salt used is shown in Table 6 after the permeation experiment after preparing the membrane by doubling the molar ratio of the repeating unit of the polymer.

Comparative example Type of silver salt Resolution (propene / propane) 1 hours 10 hours 100 hours One AgNO ₃ 15 11 3 2 AgBF ₄ 97 79 39 3 AgCF ₃ SO ₃ 83 72 35

In the case of the membranes composed of the polymer POZ and the silver salt of Comparative Examples 1 to 3 (molar ratio of silver salt / polymer repeating unit = 2), the resolution of propene to propane decreased continuously with time, and the resolution at 100 hours was Compared to the resolution at 1 hour after the start of the experiment, it was lowered to about 42%.

As described above, when the facilitated transport membrane is manufactured using the zwitter ionic silver compound, silver ions are largely stabilized by sulfonyl groups, thereby preventing silver ions from being reduced during the separation process. Therefore, even if it is operated for a long time, the permeability and the resolution of an initial stage can be maintained without degrading the performance of a membrane. In addition, the accelerated transport separation membrane containing the zwitter ionic silver compound according to the present invention has an advantage of being much simpler and cheaper than the conventional sulfonate group-containing ion exchange resin (ionomer) membrane.

Claims (8)

Next, an accelerated transport separation membrane for separating olefin / paraffin containing a zwitterionic silver compound represented by Chemical Formula 1 as a main component. Formula 1 In the formula, R is an alkyl or phenyl group having 1 to 8 carbon atoms, n is 2 or 3, and X ⁻ is an anion selected from BF ₄ , NO ₃ , ClO ₄ , CF ₃ SO ₃ , PF ₆ , and SbF ₆ . The method according to claim 1, further comprising a polymer selected from polyvinylpyrrolidone (PVP), poly (2-ethyl-2-oxazoline), polyvinyl formal, polyethylene oxide (PEO), and polyacrylic acid. Transport membrane. delete 3. The facilitated transport membrane of claim 2, wherein the polymer is contained in an amount of 10 to 50 wt.% Based on the zwitterionic silver salt. The promoted transport membrane according to any one of claims 1 to 4, wherein the material to be separated is an olefin / paraffin mixture having 2 to 6 carbon atoms or a diene / paraffin mixture.      (a) dissolving the zwitter ionic silver compound of Formula 1 in a solvent to obtain a solution containing the zwitter ionic silver compound Formula 1 In the formula, R is an alkyl or phenyl group having 1 to 8 carbon atoms, n is 2 or 3, and X ⁻ is an anion selected from BF ₄ , NO ₃ , ClO ₄ , CF ₃ SO ₃ , PF ₆ , and SbF ₆ ; (b) coating the solution obtained in step (a) on a support or glass plate; (c) promoting transporting polymer for olefin / paraffin separation containing the zwitterionic silver compound of Formula 1, comprising drying the support or the glass plate of step (b) in a state where light and oxygen are blocked; Method for producing a separator. The method according to claim 6, wherein the solvent used in step (a) is water or an alcohol having 1 to 4 carbon atoms, and is used in an amount of 1 to 10 times by weight based on the zwitterionic silver compound. The production method according to claim 6 or 7, wherein the support used in step (b) is a microporous polyester support membrane.