DD208628A1 - METHOD FOR THE ENTAROMATIZATION OF HYDROCARBON MIXTURES - Google Patents

Abstract

The object was to make it possible by separation of the aromatic hydrocarbons from hydrocarbon mixtures, the production of high purity n-paraffin cuts. This is achieved by a process for adsorptive dearomatization of hydrocarbon mixtures to crosslinked, macroporous, partially sulfonated and then preferably monovalent metal ions loaded adsorbent polymers based on vinyl and / or polyvinyl aromatic compounds. The process is suitable for production in the food, detergent and pharmaceutical industries.

Description

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VEB Leuna-Werke Leuna,

!!Walter Ulbricht!!

LP 8228

Title of the invention

Process for the dearomatization of hydrocarbon mixtures

Field of application of the invention

The invention relates to a process for the separation of aromatic hydrocarbons from hydrocarbon mixtures

Characteristic of the known technical solutions

It is known that η-paraffins of high purity are gaining in importance as starting materials for a variety of syntheses. In addition to the production of biodegradable detergents, the production of protein vitamin concentrates is of particular interest. The food, packaging and pharmaceutical industries also place high demands on the degree of purity of the η-paraffins used, in particular with regard to the separation of aromatic hydrocarbons.

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Although it is now possible to separate these aromatic hydrocarbons from hydrocarbon mixtures by means of a series of previously known processes, either the required purities of less than 100 ppm aromatics in the n-prilled concentrate are not achieved or the processes are too costly, due to large quantities circulating product flows, by a high number of processing stages or by the emergence of polluting by-products and their necessary elimination.

These are listed. Disadvantages are largely eliminated by the method described in DE-OS 2,364,333. Thereafter, the separation of the aromatic hydrocarbons from the hydrocarbon mixtures is carried out by adsorption on macroporous cation exchange resins based on styrene-divinylbenzene Kopolyraerisat. For this purpose, the hara is completely loaded with metal ions, preferably those of silver, corresponding to the exchange capacity of the resins, which amounts to 3 to 5 meq / g of dry matter, silver contents of 21 mass to 28 mass.

Desorption is carried out with polar solvents, e.g. 1,4-dioxane or, as stated in the patent DE-OS 2 550 903, made with benzene, toluene or xylene. Also ammonia is called as a possible desorbent (DD-PS 147 852).

The essential shortcoming of all these processes is the high metal content, in particular the high noble metal content, of the cation exchange resins used in the process.

Object of the invention

The present invention is intended to significantly reduce this deficiency of the known processes and thus improve their economy. "

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Explanation of the essence of the invention

The object was to develop a method in which adsorbents with significantly lower metal or precious metal contents are used.

According to the invention, this object is achieved by a process for the dearomatization of hydrocarbon mixtures by adsorption of the aromatic hydrocarbons on crosslinked, macroporous, partially sulfonated and subsequently loaded with metal and / or ammonium adsorber polymers based on vinyl and / or vinyl aromatic compounds and subsequent desorption with a polar solvent dissolved by the adsorption on partially sulfonated adsorbent polymers having a Austauschkapazitaet up to 1.5 meq / g, preferably from 0.1 to 1.3 meq / g, based on the dry matter of Saureeform have. "

The loading of the sulfonic acid-containing adsorber polymers is carried out in a known manner with a metal salt solution. It proved a load of silver as beneficial. The adsorbent polymers loaded in this way had a silver content of 8% to 11% by weight. The dearomatization of the hydrocarbon mixtures is now carried out in such a way that the liquid feedstock is conveniently carried by the filled with pretreated adsorbent polymers Sauele in Aufwaertsstroemung. If the dearomatised hydrocarbon mixture flowing off the top of the column has exceeded a predetermined limit value of the aromatics concentration, the feed of fresh feed product is interrupted and the regeneration of the adsorbent is initiated. If it is intended to selectively recover and recycle the adsorbed aromatics, it is preferable to purge the adsorbent with a light hydrocarbon such as η-hexane. If this is not the case, it is also sufficient if the adsorbent is charged with a gas, e.g. Nitrogen, argon or hydrogen is cleared from the feedstock. Following this, the

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Desorption of the adsorbed on the adsorbent hydrocarbons with a polar solvent, the direction of flow is suitably directed Säaeulenabwaerts. As desorbents, e.g. Dioxane, methanol, ethanol, isopropanol, acetone or water. After desorption, the adsorbent adhering to the adsorbent must be removed by a further rinsing step. This is expediently carried out by heating the adsorbent at a pressure of 1.3 to 2.0 kPa and a temperature of 383 K. If a volatile desorbent is used, flushing with a gas analogously to the first rinsing step is sufficient. The adsorbent is then available for another adsorption process.

Adsorbents used are crosslinked, macroporous, partially sulfonated adsorber polymers based on vinyl or polyvinyl aromatic compounds and subsequently loaded with metal or ammonium ions. Partial sulfonation under mild conditions, while maintaining the inner surface of the adsorber polyols

2 meren, which is preferably over 200 m / g, ion exchange capacity of 0.5 to 1.5 meq / g, preferably 0.8 to 1.3 meq / g, based on the H-form in the dry state achieved.

For loading the adsorber polymers with metal ions, the elements of groups Ia to IVa and Ib to VIIIb are suitable. Preference is given to loading with monovalent metal ions, for example alkali metal, Ag ⁺ or Cu ⁺ ions. A loading combination of, for example, Na ⁺ and Ag ions is also possible.

Furthermore, loading with elements of the group Ha, in particular with barium, proved to be advantageous. The adsorption proceeds at temperatures of 273 to 373 K, preferably at temperatures in the range of 293 to 353 K.

The loads are 0.02 to 5.0 volume of Bnsatzprodukt per volume of adsorbent and hour, especially 0.1 to 3.0.

The desorption is carried out with polar solvents at temperatures of 273 to 393 K, preferably at temperatures in the range of 293 to 353 K. The choice of such a temperature proves to be favorable, which makes it possible to carry out adsorption, desorption and possibly rinsing steps isothermally.

The space velocities during desorption are from 0.1 to 5 volumes of desorbent per volume of adsorbent per hour, in particular from 0.5 to 3.0. The choice of the space velocity is dependent on the type of desorbent and the amount of desorption agent used. The desorbent used can be returned to the desorption process after a distillative treatment.

When using lower alcohols such as methanol, ethanol and isopropanol, as well as acetone as a desorbent, the necessary removal of the same from the adsorbent proceeds without much effort through a simple spülschritt with a gas such as nitrogen, argon or hydrogen. In addition, these desorbents can be worked up well by distillation. When using other polar solvents for desorption, e.g. 1,4-dioxane, methyl tertiary-butyl ether (MTBE) or water, the removal of the same from the adsorbent consuming because this is a simple Spuelschritt with gas is not sufficient.

Adsorption and desorption are up to 2 MPa when pressed.

Serve as n-paraffinic hydrocarbon mixtures in the C-number range G ₁₁ to C _ig at aromatic contents of 0.1 to 2.0 mass%.

Embodiment Example 1

HO ml of a loaded with silver and pretreated at a pressure of 1.3 to -2.0 kPa and a temperature of 383 K, macroporous and partially sulfonated adsorbent polymers having a silver content of 9.2 mass% (total weight capacity: 1.24 m / g dry substance of the H ⁺ form; water content; 48.5 wt. based on the water-swollen H ⁺ form; inner surface according to the .BET method: 622 r.p. Vg), in an adsorption column in an upstream suspension with an n-paraffin section who had the following characteristics

Density at 293 K boiling point boiling end C number distribution

0.766 h / cm ³ 513 K 577 KG

11 ⁵ 12 '13

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0.2 mass 6.5 mass 23.4 mass% 24.0 mass

.1,3 mass%

13.4 ingots 7.7 masses 3.5 ingots

The UV absorbance, measured at 270 nm, was 170 for this mixture. This corresponds to an aromatics content of about 2.0 pigs.

The adsorption proceeded under the following conditions? Injection rate 44 ml / h temperature 298 K The following conditions were used for desorption:

Flushing agent nitrogen

Desorbent 1,4-dioxane

Space velocity 0.7 l / l adsorbent and hour

Temperature 343K

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Under these conditions, 2.3 l of η-paraffins were obtained per liter of adsorbent, which had an extinction of 0.8 at 270 nm.

Example 2

The experiment was carried out as in Example 1, with the changes that the desorption was carried out with methanol at 333 K and the space velocity was 2 1/1 adsorbent and hour.

Under these conditions, 2.7 l of η paraffins were obtained per liter of adsorbent, which had an extinction of 1.0 at 270 nm.

Example 3

The experiment was carried out in Example 2, with the changes that a potassium-loaded, macroporous, partially sulfonated adsorbent polymer was used (potassium content 2.8% by mass), wherein the space velocity of methanol during desorption was 1 1/1 Adsobens and hour

Under these conditions, 1.8 1 n-prfffins were obtained per liter of adsorbent, which had an extinction of 0.9 at 270 nm.

Example 4

The experiment was carried out as in Example 1, with the change that a barium-laden, macroporous, partially sulfonated adsorbent polymer was used (barium content: 4.21 mass), wherein the space velocity of the methanol during desorption was 1 1/1 adsorbent and hour. ^{1 :} "

Under these conditions, 1.6 liters of n-paraffins were obtained per liter of adsorbent, which had an extinction of 1.0 at 270 nm.

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Example 5

The experiment was carried out in Example 2, with the result that the adsorption took place at 313 K, the space velocity of the methanol during desorption was 3 1/1 adsorbent and hour, and the n-paraffin cut to be dearomatized had a UV absorbance at 270 nm of 190 had.

Under these conditions, 1.4 l of η paraffins were obtained per liter of adsorbent, which had an absorbance of 0.31 at 270 nm.

Example 6

The experiment was carried out as in Example 2, with the changes that 200 ml of adsorbent were used, the injection rate was 120 ml / h, the adsorption at a temperature of 333 K took place and the n-paraffin mixture to be de-aromatized a UV absorbance at 270 nm of 36 had. The methanol was worked up by distillation and returned to the desorption process. Under these conditions, 25 cycles were carried out. · An average of 2.3 1 η paraffins were obtained per liter of adsorbent, which had an absorbance of 0.46 at 270 nm.

The capacity loss of the adsorbent was about 5% over the entire period *

Example 7 '

The experiment was carried out as in Example 2, with the changes that the adsorption at 333 K took place, the desorption was carried out with ethanol at 343 K and the space velocity was 1 1/1 adsorbent and, Stjinde. <<i

Under these conditions 2.0 liter of n-paraffins were obtained per liter of adsorbent, which had an extinction of 0.7 at 270 nm.

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Example 8

The experiment was carried out as in Example 7, with the changes that the adsorption at 343 K took place, the desorption was carried out with isopropanol at 348 K and the space velocity was 2.5 1/1 adsorbent and hour.

Under these conditions, 1.8 l of η-paraffins were obtained per liter of adsorbent, which had an extinction of 0.81 at 270 nm.

Example 9

The experiment was carried out as in Example 1, with the changes that the n-paraffin section to be de-aromatized had a UV absorbance at 270 nm of 96, the desorption was carried out with acetone at 313 K and the space velocity 2 1/1 adsorbent and hour scam.

The removal of the desorbent from the adsorbent was carried out by purging with nitrogen at desorption temperature. A flushing time of two hours at a nitrogen flow rate of 75 l / h proved sufficient.

Under these conditions, 3.5 l of η paraffins were obtained per liter of adsorbent, which had an extinction of 0.95 at 270 nm.

Claims (10)

-ο- invention claim 1 * A process for the dearomatization of hydrocarbon mixtures by adsorption of the aromatic hydrocarbons on crosslinked, macroporous, partially sulfonated and subsequently loaded with metal and / or ammonium ions adsorber polymers based on vinyl and / or polyvinyl aromatic compounds and subsequent desorption with a polar solvent, characterized characterized the adsorption takes place on partially sulfonated adsorbent polymers which have an exchange capacity of up to 1.5 meq / g, preferably of 0.8 to 1.3 meq / g, based on the dry matter of the acid form. 2. The method according to item 1, characterized in that the adsorption is carried out on partially sulfonated adsorber polymers which are wholly or partially loaded with silver ions and / or other monovalent metal ions. 3. The method according to item 1, characterized in that the adsorption takes place on partially sulfonated adsorber polymers which are wholly or partly loaded with cations of the second main group, preferably with barium. 4. The method according to item 1, characterized in that the adsorption at temperatures of 273 to 373 K, preferably 293 to 353 K, is performed. 5. The method according to item 1, characterized in that the adsorption takes place at loads of 0.02 to 5.0, preferably 0.1 to 3.0, volume of starting material per volume of adsorbent and hour. 6. The method according to item 1, characterized in that the desorption takes place at temperatures of 273 to 393 K, preferably 293 to 353 K. 7. The method according to item 1, characterized in that the desorption takes place at space velocities of 0.1 to 5.0, preferably 0.5 to 3.0, volume of desorbent per volume of adsorbent and hour. 8. The method according to item 1, characterized in that as a desorbent alcohols, preferably methanol, ethanol and isopropanol, are used. 9. The method according to item 1, characterized in that is used as the desorbent acetone. 10. The method according to item 1, characterized in that for adsorption and desorption pressures up to 2 MPa, preferably 1 MPa, are used. λc Q