JPS647818B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for regenerating ion exchange resins Ion exchange resins have been used for various purposes. Their usage can be roughly divided into methods that utilize the ion exchange ability of ion exchange resins to adsorb various ions, and methods that use ion exchange resins to adsorb various ions, and methods that use ion exchange resins as polyvalent acids or bases to facilitate ionic reactions. There is a method of using it as an acid or base catalyst. The former method, which utilizes ion exchange ability, is used for pure water production, hard water softening, waste water treatment, and purification of glucose, sucrose, or formalin. The latter method of using it as an acid or base catalyst includes, for example, a method of using it in acid-catalyzed reactions such as olefin polymerization, etherification, or hydration. By the way, when ion exchange resins are generally produced by addition polymerization, a three-dimensional network resin matrix structure is created by copolymerizing monomers such as styrene, acrylic esters, and methacrylic esters with a crosslinking agent such as divinylbenzene. It is something that you have. In the matrix, strongly acidic cation exchange resins contain sulfonic acid groups, weakly acidic cation exchange resins contain carboxylic acid groups, phosphonic acid groups, or phenol groups, and strong basic anion exchange resins contain quaternary groups. Ammonium groups are used as ion exchange groups, and weakly basic anion exchange resins have primary amines, secondary amines, or tertiary amines as ion exchange groups. In addition to the resin matrix of ion exchange resin, which has a nearly homogeneous three-dimensional network structure called a gel type and a three-dimensional network (microbore) called a bolus type, the resin matrix has physical structures within the particles. Some have pores (macropores). By the way, when various liquids are treated using ion exchange resins, substances contained in the liquids are adsorbed and the activity of the ion exchange resins is reduced. In particular, when performing a low polymerization reaction of olefins using a strongly acidic cation exchange resin as an acid catalyst, high polymers and low polymers themselves generated together with the target low polymer are adsorbed and accumulated in the pores, and over time. As time passes, a significant decrease in catalyst activity occurs. Therefore, in the process of polymerizing olefins using strongly acidic cation exchange resin as a catalyst,
Since the catalyst life is too short, it is difficult to adopt a fixed bed flow system, and a fluidized bed or stirring mixing tank type process is usually used, which requires constant replacement of the catalyst. Even if a strongly acidic cation exchange resin whose activity has decreased due to the high polymers adsorbed and accumulated in the pores is simply washed with a solvent, the adsorbed substances such as the high polymers cannot be removed and the activity returns to its original state. It doesn't recover. In view of the above circumstances, the present inventors have researched a method for regenerating a strongly acidic cation exchange resin catalyst whose activity has decreased due to adsorbed substances adsorbed to the resin matrix in the low polymerization reaction of olefins. The present invention was completed by discovering that the degraded ion exchange resin can be regenerated by washing with a solvent in a swollen state. That is, the present invention provides a method for regenerating a strongly acidic cation exchange resin used as a catalyst for low polymerization of olefins whose activity has decreased due to adsorbates adsorbed in the resin matrix. After or simultaneously with swelling the resin with a swelling agent for the resin selected from the mixture, treating the resin with a dissolving agent for the adsorbent consisting of an aromatic hydrocarbon or/and an aliphatic hydrocarbon. A method for regenerating a strongly acidic cation exchange resin as a catalyst for low polymerization of olefin, which is characterized by the following. The adsorbate in the present invention is adsorbed and accumulated in the resin matrix of the strongly acidic cation exchange resin used as a catalyst during the low polymerization reaction of olefins such as isobutylene, reducing the activity of the ion exchange resin as a catalyst. It is a substance that causes Particularly, as mentioned above, during the low polymerization of olefins, the high polymer produced together with the desired low polymer is adsorbed and accumulated in the resin matrix, resulting in a significant decrease in the activity of the catalyst. Typical strong acidic cation exchange resins include styrene sulfonic acid type resins and phenolsulfonic acid type resins. A styrene-based sulfonic acid type ion exchange resin is a sulfonated resin obtained by copolymerizing styrene and a crosslinking agent such as divinylbenzene, and is usually represented by the following formula. Furthermore, the phenolsulfonic acid type resin is usually obtained by condensing phenolsulfonic acid with formaldehyde, and is represented by the following formula. (In both formulas, m and n are positive integers) These ion exchange resins usually have an average particle size of 0.2
It is used in the form of spherical or cylindrical particles of ~10 mm, for example, as a catalyst for the polymerization of olefins. The swelling agent used in the regeneration method of the present invention is a substance that can swell the ion exchange resin in which adsorbates, such as high polymers of olefins, have been adsorbed and accumulated in the resin matrix, such as water, methyl alcohol, ethyl alcohol, isopropyl alcohol, etc. , alcohols such as amyl alcohol, ethylene glycol, propylene glycol, phenol, and cyclohexanol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; and ethers such as ethyl ether, dioxane, methyl cellosolve, ethyl cellosolve, and tetrahydrofuran. These can also be mixed and used as appropriate. The ion exchange resin is swollen with the above-mentioned swelling agent, and then the resin is treated with an adsorbate dissolving agent to dissolve and remove the adsorbate and regenerate it. The dissolving agent used in this dissolving treatment is a substance capable of dissolving adsorbates adsorbed and accumulated in the resin matrix, such as high polymers such as olefins, aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene, Aliphatic hydrocarbons such as hexane, normal heptane, isooctane are used. Of course, a mixture of these may be used, and petroleum ether, petroleum naphtha, mineral spirits, kerosene, etc. may also be used. Further, as an example of a mixture thereof, a light reaction product during olefin polymerization can also be used, as will be described later. It is also possible to swell the ion exchange resin with a swelling agent and then treat it with a dissolving agent to dissolve and remove adsorbed matter, but rapid swelling may cause cracks in the resin. Therefore, if a swelling agent and a dissolving agent are mixed to swell the ion exchange resin and dissolve the adsorbent at the same time,
This is preferred because rapid swelling can be avoided. Particularly when using a swelling agent that tends to cause rapid swelling, such as water, the swelling agent may be added gradually while bringing the solubilizing agent into contact with the resin to avoid rapid swelling. Furthermore, a low polymer that is homologous to the high polymer of olefins adsorbed and accumulated has the ability to dissolve the high polymer. Therefore, when regenerating a catalyst when it is not desired to mix too many foreign substances into the polymerization process, a swelling agent is added while circulating light reaction products during polymerization, such as low polymers, which are the target products of the polymerization process. is the preferred method. Of course, in this case swelling and dissolution will occur simultaneously. The temperature for the treatment with the swelling agent and the dissolving agent may be selected as appropriate, but is usually about room temperature to 100°C. The regeneration method of the present invention can be applied to ion exchange resins used in any of fixed bed, fluidized bed, and stirred mixed bed formats. If it is desired to perform regeneration without extracting the resin from the fixed bed, it is preferable to provide a free space in the resin packed bed, taking into account the volume increase of the resin due to swelling during regeneration. Next, the present invention will be explained in detail with reference to Examples. Example Using the _C4 olefin fraction with the composition shown in Table 1 as a raw material,
Olefin was underpolymerized in a fixed bed flow system under the conditions shown below. Butadiene, which tends to form high polymers, has been removed from this raw material through extraction and hydrogenation, and NH ₃ and H ₂ O, which have a negative effect on ion exchange resins, have been removed from this raw material.
It does not include The ion exchange resin used as a catalyst was washed with methanol and benzene. Table 1 Raw material composition wt % i-C ₄ 5.1 C ₄ ′-1 24.0 n-C ₄ 18.6 i-C ₄ ′ 37.8 CiSC ₄ ′-2 6.2 transC ₄ ′-2 8.3 Reaction conditions Catalyst: Macroreticular type styrenic sulfonic acid type strongly acidic cation exchange resin (manufactured by Rohm and Haas, Amberlyst)
15) Pressure: 30Kg/cm ² LHSV; 2H ₂ ^-1 Recycling ratio: 5 Reaction temperature: 120℃ (constant) Although the reactor was operated under these conditions for 22 days, the amount of acid flowing out was negligible as determined by measuring the amount of acid in the effluent. Despite this, the conversion rate of olefin has decreased from the initial 93%.
It dropped to 69%. Therefore, the catalyst was regenerated after 22 days of operation.
Regeneration was carried out by using dehydrated methanol as a resin swelling agent and benzene as a dissolving agent for the olefin polymer, and washing a 1:1 mixture of the two at 80° C. through a catalyst bed. In addition, a part of the catalyst was extracted, and for comparison, washing with benzene alone and dehydrated methanol alone was also performed to examine the degree of recovery of the acid amount. In addition, a portion of the extracted catalyst was similarly washed with a 1:1 mixture of acetone and tetrahydrofuran (THF) selected as a resin swelling agent and benzene, and the amount of acid was determined. The results are shown in Table 2.

[Table] From the comparison of acid amounts, it appears that the catalyst activity was recovered by methanol/benzene washing, so the low polymerization reaction of olefin was carried out under the same conditions as before regeneration. The results are shown in the figure as the change in olefin conversion rate over time.

[Brief explanation of the drawing]

The figure is a diagram showing the effect of regeneration of the polymerization reaction, with the horizontal axis representing the elapsed time (days) and the vertical axis representing the conversion rate (%) of the polymerization reaction. In the figure, the white dotted line shows the curve for initial use, and the black dotted line shows the curve after regeneration.

Claims (1)

[Claims] 1. A method for regenerating a strongly acidic cation exchange resin used as a catalyst for olefin low polymerization whose activity has decreased due to adsorbate adsorbed in the resin matrix, in which a compound selected from water, alcohol, ketone, ether, and a mixture thereof An olefin characterized in that, after or simultaneously with swelling the resin with a resin swelling agent, the resin is treated with a dissolving agent for the adsorbent consisting of aromatic hydrocarbons and/or aliphatic hydrocarbons. A method for regenerating a strongly acidic cation exchange resin as a catalyst for low polymerization.