DD229992B5 - Process for the preparation of macroporous sulfonic acid polymers - Google Patents

Description

Characteristic of the known technical solutions

It is known to use macroporous cation exchangers in organic catalysis, as described, for example, for olefin reactions and other organic reactions which are catalyzed by H ⁺ ions (DE-AS 1168808, DE-AS 1168909, GB-PS 952422, DD -PS 147664). Furthermore, the separation of aromatic compounds from hydrocarbon mixtures by means of macroporous cation exchanger in the salt form, for example in DE-OS 2356519; DE-AS 2364306 and DD-PS147852 described. The preparation of such cation exchangers is generally carried out by sulfonation of crosslinked, macroporous vinylaromatic polymers, preferably of styrene-divinylbenzene copolymers, such as г. In US Pat. Nos. 3,147,214 and 3,201,157.

The reaction conditions in these descriptions are generally chosen so that a very complete or high degree of substitution and thus the introduction of as many sulfonic acid groups in the polymer matrix is achieved.

In DD-PS 208622 a process for the preparation of sulfonic acid-containing adsorbents based on crosslinked macroporous vinyl and / or polyvinyl aromatic compounds for the de-aromatization of hydrocarbon mixtures is described, which is characterized in that crosslinked macroporous polymers having an inner surface of at least 40m ² / g dry substance be partially sulfonated.

The features of the known inventions are that the synthesis is carried out in several steps and with the use of larger amounts of crosslinker and inert and energy and cost are through the individual substeps.

Object of the invention

The object of the present invention, while eliminating the disadvantages of known manufacturing processes mentioned, is the development of a process for the preparation of macroporous polymers containing sulfonic acid groups in an energy-efficient and cost-effective manner.

Explanation of the essence of the invention

The object of the invention was to produce such polymers on the basis of technical preliminary and intermediate products in an energy-and cost-effective way.

The known and described solutions involve the syntheses in at least two steps, wherein the formation of the macroporous polymer by polymerization in the presence of inert agents and crosslinker contents (eg divinylbenzene) generally takes place> 10% by weight and in a second step the sulfonation is carried out by known methods. Both steps are carried out separately, with different inerting agents, reaction times and reaction temperatures. It has now been found that one can produce sulfonsäuregruppenhaltige polymers in a simplified and energy-and cost-effective manner, if uncrosslinked or low-crosslinked vinyl aromatic polymers such. B. perpolystyrene or copolymers of styrene and divinylbenzene partially chloromethylated in a first reaction step and in a second reaction step by means of sulfuric acid in the presence of swelling inert agents further cross-linking with formation of porosity with simultaneous partial sulfonation.

The processes for preparing the starting polymers are known, and it is also possible to synthesize the polymers in the presence of inert agents. The crosslinker content in the process according to the invention generally does not need to exceed 5-6% by weight. Particularly cost-effective is the use of uncrosslinked polystyrene. The polymers are prepared in the usual manner by the suspension polymerization method in a grain size of 0.3-1.2 mm. A porous structure of the starting polymers is possible by the addition of precipitants or swelling agents or of linear polymers to the polymerizable phase. The use of mixtures of these classes of compounds is possible. When

polymerizable compounds are preferably styrene and / or alkylstyrene and used as crosslinking divinylbenzene. Other polyvinyl compounds such as trivinylbenzene, polymethacrylates and similar compounds can also be used.

If the starting polymer is to have a polar structure, it is preferred to add acrylic and / or methacrylic acid derivatives to the polymerizable phase.

The methods of chloromethylation of the polymers are also known. Advantageously, the introduction of the chloromethyl groups by means of monochlorodimethyl ether. The sulfonation and post-crosslinking takes place according to the invention by means of sulfuric acid in the concentration range from 94 to 100%. A particularly advantageous variant of the process according to the invention consists in the use of sulfuric acid as the chloromethylation and postcrosslinking catalyst and as a sulfonating agent. In general, therefore, the procedure is such that the sulfuric acid is initially charged and the starting polymer is suspended therein. An inert swelling agent, mixed with Monochlordimethyläther, is metered and stirred to adjust the swelling equilibrium one to two hours at room temperature. Halogenated hydrocarbons such as dichloroethane and tetrachloroethane are particularly suitable as inert swelling agent. Others are not excluded. After the swelling phase at temperatures between 40-60 ⁰ C, the chloromethylation and at temperatures> 75 ° C, the post-crosslinking and sulfonation brought about. The temperature control can be designed stepwise or continuously. The reaction times for the post-crosslinking reaction are generally between 4 and 15 hours and depend on the temperature. After the reaction, the inert can be separated together with the sulfuric acid and is then isolated, or it is - and this is the more advantageous way - removed by distillation from the reaction mixture. This variant is particularly suitable for the use of dichloroethane. The final product properties of crosslinking, internal surface area and degree of sulfonation can be controlled by the batch conditions such as polymer grade and quantity, monochlorodimethyl ether amount, type and quantity of inert agent and sulfuric acid concentration and amount. A second variant of the method according to the invention is the chloromethyl-containing vinyl aromatic polymers z. B. are prepared based on styrene-divinylbenzene copolymers prepared by any known method in the inert medium, after reaching the equilibrium swelling sulfuric acid is metered and the post-crosslinking, porosity formation and sulfonation is brought about by a stepwise or continuous heating. Again, a distillative recovery of the inert medium is the cheaper way. The recovery rate of the inert medium is very favorable in both variants. A circulation procedure of the inert agent is thus easily possible. To achieve higher degrees of sulfonation, a temperature increase to 105-11O ⁰ C is appropriate. The hydration of the end products takes place in both variants by known methods.

A further advantage of the process according to the invention is that all processes and reactions proceeding, such as swelling, chloromethylation, postcrosslinking, sulfonation and separation of the inert medium take place in a reaction vessel and partly simultaneously. Furthermore, the use of crosslinking component is much lower than known processes or when using polystyrene is not necessary at all

 The process of the invention will be further illustrated by the following examples.

Example 1:

In a sulfonating flask equipped with stirrer, thermometer and reflux condenser, 200 ml of sulfuric acid (96%) are introduced and 5 ml FeCl ₃ (1050 g / l) added slowly as a catalyst. 52 g of a polystyrene crosslinked with 1% DVB (0.3-1.2 mm) are stirred in this solution, and a mixture of 50 ml monochlorodimethyl ether, 250 g dichloroethane is metered in over a period of about 4 hours. The mixture is then at 4O ⁰ C for 4h, stirred at 50.60 and 7O ⁰ C for 1 h and at 80 ° C for 4 h. The cooled reaction mixture is filtered off, with 60% and 30% H ₂ SO ₄ , as well as with sat. NaCl solution, water and methanol. The final product provides the following analysis values:

Total weight capacity strongly acidic: 0.83 meq / g

Water content: 44.5%

Inner surface according to BET: 627.0 mVg

Residual chlorine value: 3.2%

Example 2:

In a sulphonation flask of the same equipment as in Example 1, 1000 ml of sulfuric acid (96%) are introduced and 20 ml FeCl ₃ solution slowly added. Subsequently, 235 g of polystyrene (0.5-0.8 mm) are stirred and a mixture consisting of 800 g of dichloroethane and 55 ml of monochlorodimethyl ether is metered in over a period of about 5 hours. The mixture is then stirred for an hour and dosed again 160ml Monochlordimethyläther and stirred again for one hour. Then stirred wird4h at 4O ⁰ C, each for 1 hour at 50 and 6O ⁰ C, 6h at 70 ° C and 2h at 80 ° C. The cooled reaction mixture is separated on the suction filter with 60% and 30% sulfuric acid and washed with water. The analysis of the final product provided the following characteristics:

Total weight capacity strongly acidic: 0.56 meq / g

Water content: 41.2%

Inner surface according to BET: 694.0 mVg

Residual chlorine value: 3.4%

Example 3:

In a reaction flask of the same equipment, as in Examples 1 and 2, 210 g of a polymer having a crosslinker content of 5% divinylbenzene and an inner surface of 75m ² / g presented and swelled with a mixture of 1000g dichloroethane and 160ml Monochlordimethyläther Zh . Subsequently, 800ml sulfuric acid (96%) and 20ml FeCl ₃ solution of the same nature, as in Example 1, dosed and 4h at 40 ⁰ C, 1 h at 50.60.70 ⁰ C and 8 h at 8O ⁰ C stirred , The cooled reaction mixture is again separated on the suction filter and the end product is washed with 60% strength, 30% strength sulfuric acid and water. The final product properties are as follows:

Total weight capacity strongly acidic: 0.96mval / g

Water content: 59.1%

Inner surface according to BET: 587.0 mVg

Residual chlorine value: 3.2%

Example 4:

In a reaction flask of the same equipment as in the preceding examples, 52 g of a polymer of the same type as in Example 3.2h are swollen with a mixture of 250 g of dichloroethane and 40 ml of monochlorodimethyl ether. Subsequently, 200 ml of sulfuric acid (90.3%) are metered in and the reaction at 40 ^e C for 4 h, at 50,60,70 ^e C per 1 hour and 80 ⁰ C 4h executed. The dichloroethane is distilled off at 88 ^e C. for 4 h and the final product washed with 60% hydrochloric, 30% sulfuric acid and water. It has the following end product properties:

Total weight capacity strongly acidic: 0.07 meq / g

Water content: 38,8%

Inner surface according to BET: 516.0 mVg

Residual chlorine value: 2.2%

Example 5:

In a reaction flask, as in Examples 1-4, 52 g of a polymer (0.3-1.2 mm) are presented with a divinylbenzene content of 4.5% and an inner surface of 62mVg and with a mixture of 220g dichloroethane and 37ml Monochlorodimethyl ether 2h swollen.

300 ml of sulfuric acid (96%) and 5 ml of FeCl ₃ solution of the same composition are metered. Followed by 4 h at 40 "C, 1 h each at 50,60,70 ^e C and 8 h at 80 ^e C is stirred. Subsequently, the dichloroethane is distilled off at a temperature increase within 4 h at 100 ⁰ C. The work-up is carried out as in example 4. The analysis shows the following result:

Total weight capacity maximum: 1.55 meq / g

Water content: 52.6%

Inner surface according to BET: 455.0 m ² / g

Residual chlorine value: 0.9%

Example 6:

In a sulfonating flask with stirrer, thermometer and distillation head 77 g of a chloromethylated styrene-divinylbenzene copolymers with 16.4% chlorine and a crosslinker content of 3.5% in 190 g of dichloroethane are swelled for 2 h. Subsequently, 300 ml of sulfuric acid (98.5% strength) are metered. The reaction is carried out at 40.50, 60.70 for 1 h and at 85 ° C. for 6 h. The dichloroethane is then distilled off within about 4 hours at a temperature increase to 105 ⁰ C. The product separated on the frit is washed successively with 60% strength, 30% strength sulfuric acid, NaCl solution and water. The analysis gives the following results: Total weight capacity strongly acidic: 3.81 meq / g

Water content: 42.7%

Inner surface according to BET: 5.8 mVg

Residual chlorine value: 2.1%

Example 7:

In a sulfonation flask of the same equipment as in Examples 1-5, 210 g of a chloromethylated styrene-divinylbenzene copolymer having a chlorine value of 21.8%, a crosslinker content of 5% and an internal surface area of 50.3 m ² / g in 800 g Dichloroethane swelled for 2 h. Subsequently, 400 ml of sulfuric acid (94.8%) and 15 ml of FeCl ₃ solution with a content of 1050 g / l are metered. The reaction is carried out for 1 h at 40, 50, 60.6 h at 70 and for 2 h at 80 ° C. The excess dichloroethane and the sulfuric acid are carefully filtered off with suction, washed with methanol and water.

Total weight capacity strongly acidic: 1.56 meq / g

Water content: 60.6%

Inner surface according to BET: 635.0 m ² / g

Residual chlorine value: 2.1%

Example 8:

a) In an apparatus as in Example 6, 77 g of a chloromethylated styrene-divinylbenzene copolymers having a chlorine value of 20.8%, a crosslinker content of 5% and an inner surface of 52 mVg in 200 g of dichloroethane for 2 h are swollen. Thereafter, 300 ml of sulfuric acid (98.5% strength) are metered. The reaction is carried out each 1 h at 85 ⁰ C at 40,50 and 60 ⁰ C and 4 h at 70 and 6h. The dichloroethane is distilled off within 2 hours at a temperature increase of up to 105 ° C. The product separated off on the frit is worked up as in Example 6. The following analytical values were obtained:

Total weight capacity strongly acidic: 3.42 meq / g

Water content: 58.8%

Inner surface according to BET: 413.0 mVg

Residual chlorine value: 2.6%

b) -c): The same results are obtained with the same experimental procedure but with an initial sediment value of 18.0 and 14.1%:

Initial settling value of the polymer (%): Total weight capacity strongly acidic (mva l / g): Water content (%): Internal surface area according to BET (m ² / g): Residual chlorine value (%):

b) c) 18.0 14.1 3.75 3.09 60.5 49.5 171.0 74.0 0.98 0.89

Claims (1)

Process for the preparation of macroporous sulfonic acid-containing polymers based on unvarnished or crosslinked vinylaromatic polymers, characterized in that in the first reaction step chloromethyl groups are introduced into the polymer consisting of homopolymers or copolymers of styrene and / or its derivatives, via the in one second reaction step by means of sulfuric acid of a concentration greater than 90%, optionally in the presence of iron-containing cocatalysts, in the presence of swelling halogen-containing, non-sulfonable inert agents, crosslinking and formation of porosity with simultaneous partial sulfonation is brought about. Field of application of the invention The invention relates to a process for the preparation of macroporous sulfonic acid-containing polymers which are particularly suitable for the adsorptive separation of organic substances from aqueous solutions, the adsorptive separation of organic liquid substances or for heterogeneous organic catalysis. Examples are the removal of phenols from aqueous solutions, the separation of aromatic compounds from hydrocarbon mixtures or the catalysis of alkylation, esterification or etherification reactions.