DD155036A1 - METHOD FOR THE ENTAROMATIZATION OF HYDROCARBON MIXTURES - Google Patents

Abstract

The process for the adsorptive removal of aromatic hydrocarbons from hydrocarbon mixtures on macroporous, with monovalent metal ions (silver) exchanged and highly surface active cation exchange resins has the task to enable the production of high purity n-paraffin sections, wherein the desorption phase is to be designed so that the number of necessary Reduces product flow and thus their processing is simplified. This is achieved by the use of water as a desorbent. The process is suitable for the production of high-purity n-paraffin cuts and their further processing in the food, detergent and pharmaceutical industries.

Description

7 96 ^ 4-

VEB Leuna-Werke Leuna, the 21st 11 · 80

"Walter Ulbricht"

LP 8099 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 becoming increasingly important as starting materials for a variety of syntheses · the production of" biologically cultivable detergents "has the greatest interest especially the production of protein-vitamin concentrates · Even the food , Packaging and pharmaceutical industries place high demands on the degree of purity of the η-paraffins used, "especially 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 a series of "already" known processes, either the required purities of less than 100 ppm of aromatics in the n-paraffin concentrate are not achieved or the processes are too costly. due to large volumes of circulating product streams, by a high number of processing stages or by the emergence of polluting by-products and their necessary elimination.

These cited disadvantages are in part eliminated by the process described in DE-OS 2 364 333. ", Then the separation of the aromatic hydrocarbons from the hydrocarbon mixtures on adsorptive route to macroporous cation exchange resins based on styrene-divinylbenzene copolymer made» For this purpose The resin present in the E ⁺ form is exchanged with monovalent metal ions, preferably those of silver or copper. Ketonic solvents are used for desorption, but they have the disadvantage that under the given process conditions they tend to undergo condensation reactions and thereby reduce the capacity of the cation exchange resin ,

Therefore, in DE-OS 2 550 903, mononuclear aromatics such as benzene, toluene or xylene are used as preferred desorbents. "

As a shortcoming also this process, the high distillation effort to work up the desorbent remains.

Object of the invention

By the present invention, the hitherto necessary high distillation effort is to be avoided and thus the economy is improved _β

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Explanation of the essence of the invention

It was the object of the well-known, based on the adsorption on silver-loaded styrene-divinylbenzene copolymers process to change so that reduce the product flows occurring and thus the necessary distillation effort is much lower.

According to the invention, this object is achieved by a process for the dearomatization of hydrocarbon mixtures of cation exchange resins loaded with metal ions, which have a spesifische surface of over 40 m / g and a mean pore size of about 2 500 nm, solved by the aromatic hydrocarbons see macroporous, with ' Monovalent ions of silver exchanged cation exchange resins at temperatures of 273 "to 373 K» a load of 0.02 to 5.0 volumes of starting material per volume of cation exchange resin and hour and pressures up to 2 MPa adsorbed and then by water at temperatures of 293 to 423 K, Space velocities up to 2 liters of water per liter of cation exchange resin and hour and pressures to 2 MPa desorbed »

The replacement of the resin with monovalent metal ions is carried out in a known manner via a metal salt solution. In this case, a cation exchange with silver proved to be advantageous. The resins thus replaced had a silver content of from 21 to 27% by mass, based on dry resin. The dearomatization of the hydrocarbon mixtures now takes place in such a way that the liquid starting material is passed through the column filled with pretreated cation exchange resin in upward flow. If the devolatilized hydrocarbon mixture flowing over the top of the column has exceeded a predetermined limit of the aromatics concentration, the feed of fresh feedstock product is interrupted and the regeneration of the resin is initiated. Previously, the resin is given off.

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if necessary with a light hydrocarbon such as η-hexane or a gas such as argon, nitrogen or hydrogen at temperatures of 323 Ms 393 K rinsed from the feed «The rinsing phase can also be replaced by applying a vacuum · The execution of this rinse phase but for the subsequent Desorption process is not necessary »The desorption of the hydrocarbons adsorbed on the resin is carried out with water, the direction of flow being preferably upstream. _S After desorption has been completed, the water is expediently removed from the resin at pressures of 1 to 10 kPa and temperatures of up to 423 K. * The water can but also be removed by a gas flow, similar to the rinse after adsorption "A previous treatment of the resin with a volatile, water-miscible solvent, eg. B "Methanol, accelerates this process" Thereafter, the cation exchange resin is available for a further adsorption process.

The adsorption proceeds at temperatures of 273 to 373 K, preferably at temperatures in the range of 283 to 313 K * The charges are 0.02 to 5 »0 volume of by-product per volume of cation exchange resin and hour, in particular 0.05 to 0.5,

The desorption is carried out with water at temperatures of 323 to 423 K, preferably at temperatures in the range of 333 to 373 K and space velocities of T / assers to 2 1 water per liter Kationenaustauscherhar ζ and hour, 'run in particular to 1 liter of water adsorption and desorption at pressures up to 2 MPa ·

The n-paraffinic hydrocarbon mixtures in the O-number range are preferably used as feedstock, from G ^ * to Cg at aromatic contents of 0.1 to 2.0 mass%,

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The adsorbents used are metal-exchanged cation exchangers.

shear resins with a specific surface area of more than 40 m / g,

in particular over 200 m / g «Exemplary embodiments Example 1

130 ml of a silver-exchanged macroporous cation exchange resin having a silver content of 23% and pretreated at a pressure of 1.3 "to 2.0 KPa and a temperature of 383 K were charged in an adsorption column in upflow with an n-paraffin section containing the the following characteristics: '

, Density at 293 K 0.766 g / cm ³ Initial boiling point 513 K

Siedeende 575 K

C number distribution C ₁₁ 0.2% by mass

O ₁₂ 6.5 mass% 23.4 mass% 24.0 mass% 21.3 mass% 16 ¹ 3 »4 mass% 7.7 mass% 3.5 mass%

The extinction, measured at 270 nm, for this mixture was 170 "This corresponds to an aromatic content of ca", 2.0 mass% _e

The adsorption proceeded under the following conditions:

Eirispritzmenge 25 ml / h temperature 293 E Print . 0.1 MPa

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For the desorption, the following conditions were used t

Flushing agent nitrogen

Desorbent water space velocity 150 ml / h temperature 353 K

Pressure 0.1 MPa

Following γ / urde the pressure is lowered to 10 kPa. Upon renewed adsorption, 680 ml of paraffins were obtained per liter of cation exchange resin which had an extinction of 0.60 at 270 nm,

Example 2 "

The experiment was carried out as in Example 1, with the changes that the tree speed of the Yiassers was 80 ml / h and then a treatment of the cation exchange resin with nitrogen at 373 K.

Upon renewed adsorption, 600 ml of η-paraffins were obtained per liter of cation exchange resin, which had an extinction of 0.91 at 270 nm.

Example 3

The experiment was carried out as in Example 1, with the changes that the injection quantity in the adsorption phase was 10 ml / h "and the desorption proceeded at 34-3 K.

Under these conditions, 1 225 ml of η-paraffins were obtained per liter of cation exchange resin, which had an extinction of 0.60 at 270 nm.

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Example M

The experiment was carried out as in Example 1, with the modifications that the injection quantity in the adsorption was 15 ml / h "and that the water had a space velocity of 100 · ml / h. *

Under these conditions, 850 ml of η-paraffins were obtained per liter of cation exchange resin, which had an extinction of 0.75 at 270 nm.

Example 5

The experiment was carried out as in Example 1, with the changes that the desorption was carried out at 333 K at a space velocity of 100 ml / h. After desorption Yiurde was rinsed with 200 ml of methanol and the resin was then heated in a stream of nitrogen 333 K. reactivated ·

Upon renewed desorption, 1 500 ml of η-paraffin was obtained per liter of cation exchange resin, which had an extinction of 0.50 at 270 nm.

Claims (7)

invention claim 1. A process for the dearomatization of Kohlenwasserstoffgemi-. see by a cyclic adsorption-desorption on metal ions of the first subgroup of the Periodic Table Loaded cation exchange resins having a specific surface area of over 4-0 m / g and a mean pore size of over 2500 nm, characterized in that the aromatic hydrocarbons to macroporous , cation exchange resins exchanged with monovalent ions of silver at temperatures of 273 Ms. 373 K, loading of 0.02 Ms 5. 0 volume of by-product per volume of cation exchange resin and hour and pressures Ms 2 MPa adsorMert and then by water "at temperatures of 293 Ms 423 K, space velocities" to 2 liters of water per liter of cation exchanger resin and hour and pressures Ms 2 MPa desorMert and that the adsorMerte water by reducing the pressure to 1 to 10 kPa or rinsing with a volatile, water-soluble solvent and subsequent discharge of the same by a gas stream is removed » 2i Method according to item 1, characterized in that the adsorption is carried out at temperatures of 283 to 313 K. 3. The method according to item 1, characterized in that the adsorption is carried out at loads of 0.05 to 0.5 volume of starting product per volume of cation exchange resin and hour. 4, method according to item 1, characterized in that the desorption is carried out at temperatures of 293 to 373 K. « 22 5 7 96 5 »Method according to item 1, characterized in that the desorption is carried out" at space velocities of 0.1 "to 1.0 liter of water per liter of ion exchange resin and hour * 6 «Method according to item 1, characterized in that pressures of 1 MPa are used for adsorption and desorption * 7 * Method according to item 1, characterized in that n-pa raffinated hydrocarbons of the O-number range C ^ _x , his CLo be dearomatized with 0.1 to 2.0 mass / 5 aromatics *