DD158331A3 - PROCESS FOR GENERATING AN N-HEXAN-rich solvent for ETHENPOLYMERIZATION - Google Patents

Abstract

The invention relates to a process for producing an n-hexane-rich solvent for ethene polymerization, which meets the quality requirements, especially the polymerization test. According to the invention, a hexane-containing fraction is separated from the feedstock, a raffinate of an aromatics extraction, contacted on a catalyst known as reforming and then subjected to fine distillation to obtain a hexane cut in the boiling range of 338-343 K, wherein the order of pre-distillation and catalytic treatment can be reversed.

Description

225785

Process for producing a η-hexane-rich solvent for ethylene polymerization

C 10 G 23/00

Anwendungsge Biet de r He-making

The invention relates to a process for the production of a predominantly η-hexane-rich solvent for ethene polymerization from the eaffinate of an aromatics extraction from a catalytically reformed gasoline.

Characteristic of the known technical solutions

It is known that a number of quality requirements are placed on the solvent for the polymerization of ethene. They concern the substantial freedom from polar, olefinic and aromatic compounds, the maintenance of a maximum permissible content of naphthenes, the maintenance of a narrow boiling range and vapor pressure and the fulfillment of the requirements of the polymerization test. The polymerization test is the decisive quality feature for the suitability of the solvent for the Ethenpolymerisation, while the other quality data are necessary, but not necessarily describe the suitability.

The essence of the polymerization test is in the polymerization of ethene at atmospheric pressure in .dem hexane solvent with. the catalyst diisobutylaluminum hydride titanium tetrachloride, with strict · to the exclusion of oxygen and water

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to observe the following conditions:

Misobutylaluminiumhydrid-titanium

tetrachloride · = 0.4 μmol: 1 mole

Concentration of titanium tetrachloride '= 4 m mol / l solvent

Polymerization temperature = 323 K polymerization time = 60 min

Ethylene flow = 50 1 USN./h.

Solvent quantity = 250 ml

Catalyst Mixture Holder from

Ethene introduction = 30 min in nitrogen

electricity

The polymerization is stopped by addition of 20 ml of butanol, the resulting polymer is filtered off with suction through a vacuum with .300 ml of methanol and weighed *

In evaluation of the polymerization test, the mass of the polymer is compared with that of reference samples and evaluated the suitability of the solvent. The evaluation also takes into account the melting point and the weight of the debris.

P. Gotthard and J. Minea describe in Acta chim. Be Hung. 36 (1-4) 113-124 ('1963) discloses a process for producing η-hexane as a solvent for the polymerization of olefins, which comprises the following steps of preparation:

Separation of the lighter than η-hexane boiling fraction from the P _L affinate of an aromatics extraction from a catalytically reformed gasoline by continuous rectification

Deposition of the crude n-hexane concentrate from the heavy fraction of the first rectification

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Removal of the benzene and reduction of the concentration of unsaturated hydrocarbons by selective adsorption on silica gel

- Removing the unsaturated hydrocarbons by sulfuric acid refining in countercurrent in an extraction column

The process has the disadvantage that for removing the remaining quantities of benzene and olefins, two technically complicated process steps must be used, namely adsorption on silica gel and sulfuric acid refining in the gas stream.

Furthermore, it is known that a η-hexane-containing and suitable for the polymerization of ethene fraction by extractive distillation and subsequent distillation can be obtained (DD-WP 78 044, DD-WP 31 301, DE-OS 27 45 672).

These processes have the disadvantage that the required product quality, in particular the Beηzeηgehalt to be reduced to less than 100 ppm, not be achieved * 'Furthermore, the removal of the olefinic product components in trace concentrations is not given with certainty. The same is true for the removal of the polymerization of ethene-interfering complex of polar compounds in both said procedures. As a result, the requirements for the solvent evaluated in the polymerization test become insufficient. Fulfills, ·

Object of the invention.

The object of the invention is a powerful one and among others with respect to the quality variations of the

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Raw material flexible, technologically simple process with improved technical and economic parameters for obtaining a η-hexane-richη, naphthenearmen and up to traces of benzene-free solvent, in particular the polymerization test with ethene at least good. corresponds and is suitable for large-scale polymerization of ethene.

Explanation of the essence of the invention

The object of the invention is to develop a process which allows the production of a η-hexane-rich η solvent for ethene polymerization under technologically simple and industrially usable conditions.

Of importance for the applicability of this solvent are its purity and a certain ratio of the main components to each other. The quality of the ethene polymers and their yield depends essentially on the quality of the solvent. The following requirements must be met for the solvent:

Polymerisation test t good to very good composition according to main components:

i-hexane and boiling lower <35 Ma.-J η-hexane ^ 50 Il Methylcyclopentane <10 Il Cyclohexane · <1.8 η i-heptane and boiling higher <3.0 W Bromine consumption «c 0,1 g Br _2/1 00 ml Benzen "<100 Ma-RPPM Sulfur <T 1. ' ppm

5 - 2 25 7 85

With the following inventive procedure, a η-hexane-rich solvent can be produced with the above-mentioned qualities 5 in particular good to very good results in the polymerization test can be achieved. From the feedstock, a raffinate of the aromatics extraction from a catalytically reformed gasoline, a fraction containing η-hexane in the boiling range of .large 310 - 343 K is first distilled off by continuous rectification (predistillation). Subsequently, the complex of the polymerization-disturbing compounds and the olefins are removed from this distillate by reaction with a hydrogen-containing gas on a fixed bed catalyst. There are a case of bromine of less than 0.1 g _Br2 / 100 ml and a benzene content. set in the Spusenbereich. A final fine distillation produces a hexane cut in the boiling range from 338 to 343 K. According to the invention, it is possible to use a catalyst known as reforming contact, which consists of a combination of one or more platinum group metals with AlpOo. Preferred for the reaction is a catalyst which consists of 0.1-1.0 Ma .- $> of a Pt metal, combined with a little azidem yu and / or ^ -AIpOohaltigen material exists.

The Al ₀ Oo-containing material has a total

pore volume of at least 0.6 cm / g, wherein 20 - 70 ° b of the pore volume on pores with a radius of 13 - 100 A and 30 - 80 i> the pore volume on pores

with a radius of about 1000 A omitted.

The reaction temperature is 373 - 580 K, the pressure

3 3

3.5 - 4.5 MPa, the contact load 3-7 m / mh and the gas / product ratio 50 - 200 rar iN / m.

2 2578

In this procedure according to the invention, it is permissible to carry out the process steps of the pre-distillation and the catalytic reaction also in the reverse order.

The series of experiments described below demonstrate the influence of the special conditions and of the catalyst on the preparation of a solvent suitable for the polymerization of ethene.

In a conventional contact testing apparatus, various catalysts have been tested under pressure for their suitability to remove the complex of polymerization-interfering, olefinic, as well as olefinic, compounds as a whole.

The contact testing apparatus consisted of a product injection, metering of a hydrogen-containing gas, heated reactor with preheating zone, cooler and scraper vessel.

Table 1: Versuohsbedingungen and results

Experiment No. K catalyst MPa temperature print m ³ ioN./m ³ G-as / product relationship m ³ / m ³ .h catalyst burden cm catalyst amount bromine consumption g _Br2 / 100 ml of the mission domestic product Ma-ppm Sulfur in the Einsatζprodukt. g _Br2 / 100 ml bromine consumption of the raffinate fitness polymerization test Schwefelkon Ea-ppm concentration in the Raffinate '

Ni-Mo-sulfide 4, .2 Ni-Mo-sui on Al ₂ O ₃ less 1 on Al ₂ O ₃ 623 0.15 573. 4.0 barely 3.5 100 100 5 5 150 150 • 4.2 smaller 1 ' 0.10 barely

3

Pt a Al ₂ O 3 4.0

₂₃ 563

100

150

4.2

'4

Ni-Mo on Al ₂ O ₃ 580 9.0

250

150

4.2

smaller 1. smaller

less than 0.05 less than 0.05

very well

barely

less than 1 small

2 2 5 7 8 5

• lentils 2

In a Kontaktpriifapparatur according series of experiments the influence of temperature on _a product quality was produced ty the solvent for ethylene polymerization examined "

Table 2; Te ^ mOperature mf I Luss 2 3 Experiment No. • 1 3o Pt up Pt on catalyst Pt on Alg ( 563 623 temperature K 473 3.5. 3.5 print MPa 3.5 Gas / product 100 100 relationship m ³ i _e N / m ³ 100 Kat alys at ο r 5 5 burden m / m oh 5 catalyst 150 150 amount cm 150 Br omverb rough ch of use 4.1 4.3 product g _Br2 / 100 ml 4.2

Sulfur in use

dulct ppm smaller 1 smaller Ί smaller

Bromine consumption of the raffinate g _Br2 / 100 ml less than 0.05 "0.05" 0.15 Polymerization suitability good very good moderate sulfur concentration smaller in the raffinate less than 1 less than 1 ppm

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The technical conditions for producing a hexane cut in the boiling range of 338-343 K are explained below with reference to FIG.

The raffinate of the aromatic extraction 1 is separated in the pre-distillation A in the bottom product 2 and the top product 3. The top product is separated in the container B in reflux 4 and distillate 5. The pre-distillation A equipped with 40 trays works at a raffinate 1 of the boiling range 310- 390 K and a content of η-hexane of 18, methylcyclopentane of 2.4 and benzene of 0.2 Ma.-4 at a top pressure of 0.18 MPa, a capitate rat ur of 357 K and a reflux ratio of 3 ·

The distillate 5 is at 4 MPa with a water containing 6 gas in the ratio 1s100 v? / V? mixed so that a molar hydrogen concentration of 0.35 is established. The mixture is heated in the heat exchanger C and in the oven D to 560 K reaction temperature.

In the reactor E, the degradation of the interfering olefinic and aromatic compounds and the complex of the polymerization disturbing so that the bromine consumption of 4.8 g Bro / 100 ml in the distillate 5 drops to less than 0.1 g Brg / 100 ml in the stripper product.

The contact load is 5 nr / m .h. It is used a contact, which has a diameter of 2 mm with a length of 3 - 10 mn and. from 0.6 Mao - $ platinum, combined with Al ^ O ^. After pressure flows of the heat exchanger C is in the separator? the reaction product gas 7 and stripper product 8 are separated ·

-

The gas 7 is led out of the plant, but it can also partially after. Compression be added to the hydrogen-containing gas 6. '

The stripper product is separated in the final distillation G, an ectification column with 60 trays, in braided product 10 and the desired solvent 9. «

The top product is in the container H in the return 12, the distillation gas 11 and the distillate '13 separate The Peindestillation G operates at a top pressure of 0.4 MPa, a head temperature of 382 K and a return ratio of 5 ".

From the raffinate of Aroraatenextraktion the following solvent is obtained. Table 3

Table 3:

raffinate

solvent

Composition of 27.0 29 , 0 Ma ο S Main components: 17.9 61 _? 5 It , i-hexane and deeper 2.4 8th 3 It boiling 0.3 0 Il η-hexane ,1 Methylcyclopentane 52.4 1 , 05 ti cyclohexane 4,8 " less than 0 g Br _2/1 i-heptane and higher 1 less 1 001 Ma "ppm boiling 0.2 0 0 " bromine consumption 682 , '669 kg / m ³ Sulfur smaller 40 65 ⁰ C benzene .47 67 ti Density at 20 ^° C. 64 68 ti Boiling range boiling point 79 68 I! 10 Vol - # · 87.   , 68 ti 30 » 106 , 68 Il 5.0t ^? , 70 ·. ' 90 ^{! L}

Claims (1)

invention claim 1 ... A process for producing a η-hexane-rich η Losungmit.tels (9) for Ethenpolymerisation from. Raffinate of an aromatics extraction from a kata- 'lytisch reformed gasoline (1), characterized in that from the raffinate (1) a hexane-containing fraction of Siedebe'reiches of greater "310 - 343 K (5) is separated by distillation, this with a hydrogen-containing Gas (6) on a catalyst of the type of one or more Pt group metals, combined with AlpO 2, when setting a bromine consumption of less than 0.1 g Brp / 100 ml, at 370-580 K, 3.5-4.5 MPa Total pressure, one 3 3 Contact load of 3-7 m / m »h. and a gas / product ratio of 50 - 200 nr ί · ϊΓ · / πΓ is contacted and then to obtain a hexane section in the boiling range of 338 - 343 K, a fine distillation (G) is performed, the order of "pre-distillation and catalytic Reaction can be reversed. Process according to claim 1, characterized in that, for the catalytic reaction, a catalyst consisting of 0.1-1.0 Ma · $ of a Pt metal, -12 - ¹² - 2 2.5 7 combined with a little bit of azide y and / or oo-containing material is used wherein the Al ₉ O ^ -containing material has a G esamtporenvolumen of at least O ₅ 6 cm / g and 20 - 70 % of the pore volume on pores having a radius of 13 - 100 A and 30 - 80 % of the pore volume on pores with a radius of about 1000 A omitted. For this purpose 1 ropes drawings