DE1668460A1 - Process for the catalytic rearrangement of alkyl aromatic hydrocarbons - Google Patents

Description

DR. E. WIEGAND 800OMONCHENIs, 'Ig. lari 1968

MONKS NUSSBAUMSTRASSE 10 UCJiIl DIPL-ING. W. NIEMANN phone = 55547 «....

HAMBURG
PATENT LAWYERS 1668460

W. 1 3506/68 9 / sw

MOBIL OIL GOEPOEATION New Tork, New York (Y.St.A.)

Process for the catalytic rearrangement of alkyl aromatic hydrocarbons

The invention relates to the catalytic conversion of alkyl aromatic hydrocarbons and in particular a process for catalytic isomerization carried out at low temperature and in the liquid phase and / or disproportionation of alkyl aromatics.

The catalytic intra- and / or intermolecular Rearrangement of alkyl groups in alkyl aromatic hydrocarbons to form one or more products for use in the petroleum and chemical industries have been carried out with a variety of catalysts. Acid halides, such as aluminum chloride, Aluminum bromide, boron trifluoride-hydrogen fluoride mixtures etc /., are involved in the rearrangement of alkylbenzenes !! to produce

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The production of valuable intermediate products that are used in the synthetic production of rubber, plastics, fibers and dyes has been used. Other catalysts used include solid silica-containing cracking catalysts such as silica-aluminum oxide and clays. Although such catalysts have one or more desirable properties, the majority of the catalysts used to date have various disadvantages. Acid halides, such as aluminum chloride, are partially soluble in the feed and are easily lost from the catalyst zone. Catalysts of this type are still technically and economically unfavorable because of their very strong corrosive behavior and the need to recover them from the effluent products. Other heterogeneous-type catalysts, such as silica-alumina, do not have sufficient acidity to effect effective conversion and require the use of relatively high fines. above sths. 427 ° 0 (800 ⁰ F). High temperatures often lead to coke formation, which reduces the yield of the desired product and necessitates frequent regenerations of the catalyst to remove coke. This leads to a reduction in the usable operating time and to a high catalyst consumption due to a loss of catalyst activity,

It has now been found that the disadvantages explained above can be avoided if the catalytic

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see the deposition of alkyl aromatic hydrocarbons in the liquid phase and at low temperature in the presence of a high-activity crystalline aluminosilicate catalyst. According to the invention, a regulated isomerization and / or disproportionation of alkyl aromatic hydrocarbons is carried out at low temperatures below about 516 ΰ (60C ⁰ F); there are increased yields of usable products with the lowest possible formation of undesirable products. The invention "allows high levels of activity and selectivity to be maintained over long operating times in the catalytic isomerization and / or disproportionation of alkyl aromatic compounds.

In the case of the ki ^ istalline aluminosilicates, which are used in the Production of the catalysts used according to the invention are used it can be either un natural or synthetic zeolites. These materials exist in the v. lateral from the dehydrated forms of crystalline v / ater- and silicon-dehydrated zeolites, the different !.! close to alkali metal and aluminum, with or without other ketals. The atoms of the alkali metal, SiI ic rums, aluminum and oxygen are in these zeolites in foru of an aluainosilicate as in a certain and permanent crystalline luster arranged. The structure contains a large number of small cavities connected by a number of even smaller holes or channels

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BATH

are. These cavities and channels are essentially of uniform size. That in the production of the invention The alkali aluminosilicate catalyst used has a uniform pore structure with openings opening through an effective pore diameter of more than 6 and less than 15 angstrom units are characterized, the openings are large enough to accommodate the molecules to be transformed Admit hydrocarbon feed. The preferred crystalline aluminosilicate zeolites are iron rigid three-dimensional network created by a system of cavities and connecting channels or pore openings is marked; the cavities are connected to one another in three dimensions by pore openings or channels that Minimum diameter greater than 6 Angstrom units and. fewer than 15 angstrom units. A typical specific example of such a structure is that of the mineral Faujasite.

Typical crystalline aluminosilicates useful in the invention are, for example, naturally occurring Zeolites, e.g. mordenite and faugasite, and the synthetic ones Materials such as synthetic mordenite and the zeolites x, y and ß. High aluminosilicates are particularly preferred Silicon dioxide content, which is an atomic ratio of silicon to aluminum have more than 1.8, e.g. the zeolites y and ß and mordenite.

The process for the production of such alkali alu

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minosilicates generally include heating a suitable one Geinischs of oxides or materials, their chemical compositions completely as a mixture of oxides

⁰ -, HPO siop and can be expressed, in aqueous solution at a temperature of about 10O ⁰ C for periods of 15 minutes to 90 hours or more. The product that crystallizes in this hot mixture is separated therefrom and. washed with water until the water in equilibrium with the zeolite has a pH value in the range from 9 to 12, and then dehydrated by heating by heating a mixture of oxides or materials whose chemical compositions are fully expressed as mixtures of the oxides ITa ₂ O, Al ₂ O- ,, T (G ₂ H ₅ ) ^ II) ₂ O, SiO ₂ and H ₃ O v / can ground, in aqueous solution, expediently at a temperature of about 75-200 G, until crystallization occurs. The composition of the reaction mixture, expressed by the molar ratios, preferably falls within the following ranges:

Si0 ₂ / Al ₂ 0 _x from about 10 to about 200;

Iia ₂ 0 / TetraäthylaiüBioniumhydroxyd from about 0.0 to 0.11

Tetraäthylai: imoriiuiiihydroxyd / Si0 ₂ from about 0.1 to

about 1.0;

HpO / tetraethylammonium hydroxide from about 20 to

about 75 · i

C 9 $ 3 3 / * 4 1 S.

The crystalline aluminosilicates are characterized by a high catalytic activity which is imparted to them by the base exchange of the alkali metal with a base exchange solution to replace all or at least a considerable proportion of the original alkali ions with other cations. Such cations include metal cations such as calcium, magnesium, manganese, chromium, aluminum, zirconium, vanadium, nickel, cobalt, iron, rare metals and mixtures of such cations. Suitable non-metallic cations include hydrogen ions or ions which are capable of converting into hydrogen ions, s »B. Ammonium ions, etc. The contact between the alkali exchange solution and the crystalline aluminosilicate is chosen so that replacement of the alkali metal ions of the material is brought about to such an extent that the alkali metal content of the composition after the base exchange is less than 4% by weight. and preferably less than about 5 % by weight.

After the base exchange treatment, the product becomes removed from the treatment solution. Anions produced by the Treatment with the base exchange solution introduced by washing the treated composition with water for a period of time until the material is free of such anions. The washed product is then dried, generally in air, in order to remove practically all of the water therefrom. Although the ! TrocM.iiu.tg can take place at ambient temperature, it is

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more convenient to facilitate the removal of moisture by keeping the product for 4 to 48 hours "at a temperature between about 65 and about 316 C (150 600 ⁰ F)"

The dried material is then subjected to an activation treatment; this is important to make the composition catalytically active. Such a treatment includes heating the dried material in an atmosphere that does not adversely affect the catalyst, see 3. in air, nitrogen, hydrogen, exhaust gas, helium or another inert gas. Generally, the dried material is heated in air to a temperature in the range of about 260-815 ° C (500-150C ⁰ F) for a period of at least about 1 hour, and usually between 1 and 46 hours. The finished product has a surface area in the range of about 100 - 700 m / g «

Catalysts suitable for the process according to the invention can also be prepared by pre-cleaning the base-exchanged form of the aluminosilicate, as described above, with a matrix of hydrous oxide, for example clays or inorganic oxide gels. The crystalline aluminosilicate can be dispersed in the matrix in widely varying amounts in the range from 1 to 95 % by weight or combined with it in another way; it is preferably used in amounts in the range from 2 to about 50% by weight. based on the total composition.

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In the case of the feedstocks for the catalytic rearrangement of alkyl aromatic hydrocarbons it can are alkylbenzenes, e.g. toluene, the xylenes, propylbenzenes and, in general, mono- or polystyrene benzenes. The input material may also include diaromatics such as alkyl naphthalenes. Generally it is the feedstock an alkyl aromatic hydrocarbon with 7 to 15 carbon atoms, either in largely pure form Form or in the form of a hydrocarbon fraction rich in alkyl aromatics. Preferred -alkylbenzenes are toluene and xylenes, since toluene disproportionates the more valuable products benzene and xylenes and the xylenes to the greatest possible extent Yield of desired isomers can be isomerized.

The process according to the invention is carried out in the liquid phase at a temperature below 316 ° C (600 F) and preferably in the range of 149-316 C (300-600 F). The pressure can range from atmospheric or less up to a pressure sufficient to maintain the feedstock in the liquid phase, e.g., 0 to 140 atmospheres (0-2000 psig). 260 ⁰ C (300 - - 500 F) In general, the isomerization reaction at a temperature of about 149 is performed while the disproportionation reaction .of appropriate at a higher temperature in the range of about 204 - 316 ° G (400-600 ⁰ F), and preferably in the range of about 260-316 ⁰ C (500-600 ⁰ F) is carried out.

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During the rearrangement reaction, hourly liquid flow velocities (LHSY) in a wide range, about 0.1 to 25 »can be used. Preferably the space velocity is in the range from 1 to 10 as the conversion increases with an increase the space velocity decreases, although the selectivity is generally increased.

In the method according to the invention, the from the rearrangement of the alkyl aromatic hydrocarbons resulting products are subjected to suitable separation treatments for recovery. Such separation processes, such as crystallization, Use of complexing agents or distillation are known.

example 1

O-xylene was isomerized and disproportionated by contact with a rare sorbent-3 acid aluminum silicate catalyst. The catalyst was prepared by exchanging the base of zeolite χ with rare earth chloride and aramoniuin chloride solutions and subsequent heating; a material was obtained containing about 25 % rare earth oxides calculated as SE ₀ O _x . This was then incorporated into a silicon dioxide-aluminum oxide matrix in an amount of etv / ε 5 ~ / °. The catalyst contained less than 4% by weight of sodium.

The conversion of the o-xylene on the catalyst took place in the liquid phase at a pressure of 28 atü (400 psig), a leniperatm? from 17? ^c 0 (35Ο ° Γ) uM a ^ bt

6/141

1668480

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Chen hair flow rate of xylene (liquid) clay 0.25 «The. obtained after 750 and 70 minutes of operation Results are shown in Table I below.

table I.

Isomerization-Disprcportionierimc of o-xylene in liquid phase at 177 ° 0 (350 ⁰ F)

feed
(percolated
o-xylene,
Phillips)

product

Operating time, min Analysis _$ wt. %

750

1170

light components 99.7 heavier than trimethylbenzenes 10C ₁ O 0.1 0.1 benzene 0.3 0.2 0.2 !Toluene Conversion, wt% Gl e i ehgewicb-t 2.7 3.4 in- and p-xylene Selectivity, wt. ~% - 23.2 27 Λ o-xylene slight proportions 47o7 70.6 65 * ^:; Trimethylbenzenes (1,3,5) benzene 22.45 0.4 C, 3 (1,2,4)
(1,2,3) toluene 37.20 2.4 2.3 m- "and p-xylene 29.15 0.1 0.1 Trimethylbenzenes 6.91 0.3 0.4 Ietraraethylbenzenes 0.22 1OD, 0 100.0 Pentainethylbenzenes 29.1 34.4 at 177 ° ö (o-xylene
free 0.3 0.3 0.7 0.6 9.3 9.9 79.8 79.7 8.9 8.4 1.0 1.1

Isomerization / (wt)

100.0

0.39

100.0

3.95

100.0

3.93

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Example 2

Toluene was disproportionated in the liquid phase over a rare earth acid catalyst similar to that of Example 1. As Heaktionsbedingungen mirden a temperature of 232 - 274 ° C (4-50 - 525 ° ί?), A pressure of 28 atm (400 psig) and an hourly Raumströarangsgeschwindigkeit of ^r £ oluols (liquid) eingeiiaUEii of 0.5.

Those obtained after 150 and 420 minutes of operation Results are shown in Table II.

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Table II

Selectivity in the disproportionation of toluene in the liquid phase at 232 (45 0 -

feed heavier than trimethyl - product product (Si-GeI benzenes 100.0 at at percolated 232 ° ö 274 ⁰ C Toluene) Recovery, wt% (450 ⁰ F), (525 ⁰ F), Conversion, wt .- $ o balance 150 min 420 min Analysis, wt. % (on toluene slight proportions free base) benzene 0.2 232 ° C 274 ° 0 3.8 10.6 toluene 99.8 90.5 73.7 m- and p-xylene - Selectivity, wt .- $ 3.5 10.2 o-xylene __ slight proportions 45.9 45.7 1.2 2.5 Trimethylbenzenes benzene 36.0 35.7 0.8 2.7 m- and p-xylene 9.1 9.5 o-xylene 9.0 9.1 0.2 0.3 heavier than xylenes 100.0 100.0 100 100 9.3 26.1 _Ml _ _l __ 38.7 39.8 37.7 39.1 12.9 9.6 10.7 11.5

100.0 100.0 100.0

100.0

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Example 3

The Hydrogenoim of Mordenite was made, by using the sodium form of synthetic mordenite Ion exchange is converted into the ammonium form and then galvanization converts the ammonium form into the hydrogen form was made. The resulting catalyst contained and had 0.04 wt% sodium by analysis a silicon / aluminum ratio of 5: 1.

Example 4

The hydrogen form of zeolite-y was produced, by ion-exchanging the liatric form of zeolite y in the ammonium form was converted and then the ammonium ions were converted into hydrogen ions by calcination. Of the According to analysis, the resulting catalyst contained 0.1% by weight> o ITodium and had a silicon / aluminum ratio of 4.3: 1

Example 5

The hydrogen form of zeolite ß was produced, by using the sodium tetraethylammonium form of zeolite ß to convert the tetraethyl ammo niumione η was calcined in hydrogen ions. The resulting catalyst contained according to Analysis 0.75 wt .-; # Sodium and it had a silicon / Aluminum ratio of 10.4: 1.

The catalysts of Examples 3 to 5 were on. their ability to convert xylene into xylene isomers and disproportionate products, such as benzene, (trimethyl and

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Tetramethylbenzenes, checked. 200 ml of pure o-xylene and 3 g of catalyst in the liquid phase were ^{reacted in a shaking bomb at 204 0} G (400 ° F), the following results were obtained after 10 hours:

Tabel III Disproportion
nation, ^ - Gej /. - ^c / o catalyst total
conversion,
Wt% Isoaeri-
ization,
Weight fo 1.2 Example 3 2.0 0.8 13.3 Example 4 25.8 7.5 1.0 Example 5 4 _t 7 3.7 Example 6

It was toluene over a Y / hydrogen Seolite y catalyst, produced v / ie in Example 4, at 260 ° C (500 J?) in a flow reactor at an hourly. Skin flow velocity the liquid disproportionated by 1. The Eeaktion was by a pressure of 35 atm (500 psig) kept in the liquid phase. The results after one hour of operation are shown below:

Table IT

Conversion, wt% 35 »1

Selectivity, wt. -%

slight proportions 1.7 benzene 8.4 toluene 64.9 Xylenes 19.5 Trimethylbenzenes 5.5

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Claims (1)

Claims 1. Process for the catalytic intra- and / or intermolecular rearrangement of alkyl aromatic hydrocarbons untex * Isonerxsierunfjs- und Disproportionierurijsbec.inyunßen in the presence of a crystalline AlurninosiMcatkatalysators with an Allialimet all content of less ice 4 Gev; .-? Ö, thereby jjekennseiclinet .ian converting to liquid! ¹ phase at a temperature below about 5iG ° G (6CC ⁰ E) carries out. 2. Ycx'J'rhr-eii according to claim 1, characterized , äa: ~ nan air allr ^ laroi-atic hydrocarbon xylene used and this "at a temperature up to au etv / a 260 C ^ vO I?) iBOu 5. The method according to claim 1, characterized in that toluene is used as alir / laronatic carbon dioxide and this at a Q? Empex * a ^ ur of about 260 to about 316 ° 0 (^ CO - 600 ⁰ P) Dispropoi-cioniert. M-, characterized Method according to one of the claims 1-3, "there is a £ catalyst / verv ends, having its Aluminosilieat a Siliciura / AluainiuiTi-AtoEiverhältliis of over 1.3. 5. Verf aliren according to one of claims 1-4, characterized marked there. *? nan used a catalyst d. its alurainosilicate hydrogen, ammonium, rare earth, 109836/1413 divalent! detail, tetramethyl ammonium or tetraätliylanmonruiiilcationen or avoiding .. of such cations. I09836 / U19 BATH