DE2040556C3 - Process for the production of benzene, toluene and polymethylbenzenes by catalytic cracking of heavy aromatic hydrocarbons - Google Patents

Description

the heavy aromatic hydrocarbon mixtures used according to the invention can be contained • cn, is ethyl toluene.

The catalyst used in the process of the invention consists, as mentioned, mainly of aluminum oxide, which is 0.01 to 10 percent by weight, preferably Contains 0.1 to 5 percent by weight fluorine.

The catalyst activity can be increased by adding other effective elements such as magnesium, zinc, silicon © or boron. The proportion of these additional elements is generally from 0.01 to 10 percent by weight, preferably from 0.1 to 10 percent by weight, based in each case on the catalyst. The catalyst used according to the invention can be prepared by a wide variety of methods. B. activated aluminum oxide with an aqueous solution of suitable water-soluble fluorine compounds, such as HF, NH ₄ F, HBF ₄ , H, SiF ₆ , Mg (BF ₄ ) -, MgSiF ₅ , CaSiF ₆ , NH ₄ BF ₄ , (NH,), Treat SiF ₆ or ZnSiF ₈ . Instead of such an aqueous solution, HF, SiF ₄ or BF ₃ can also be used in the vapor phase. Another advantageous process for preparing the catalyst is that aluminum oxide sol or silicon dioxide-aluminum oxide sol by adding fluorine ent resounding acidic compounds, such as HF, H ₂ SiF ₆ or HBF ₄ , is brought to gel and the gel obtained is then dries unticked. The fluorine-treated catalyst is very active and has a longer useful life than an untreated catalyst.

In the Durchiöhrung of ^v * he ^r ahre "s of the invention, the Ausgangsmalerial zLvor is heated and vaporized before it bed Katalysato-in dei vapor phase with the in Touch, is brought g. The vaporous Ausgangsmaterii can! For reducing the carbon deposition on the catalyst with another gas, * ie hydrogen, nitrogen, water vapor, lower paraffinic hydrocarbons, e.g. methane, ethane or propane, or a gas mixture consisting of the aforementioned compounds. Preferably, hydrogen or a gas mixture consisting mainly of hydrogen are used as the diluent The vapor of the starting material is preferably diluted a * if more than twice "and up to about 60 times its volume.

In the process of the invention, temperatures of from 400 to 70.degree. C., in particular from 450 to 650.degree. C., are preferably used. If too high a 1 emperalur is used, the catalyst can degrade. If the temperature is too low, the reaction takes place too slowly.

The optimal loading speed depends

gen, the type of catalyst and the composition of the starting material. Irr general w.rd however, the starting material has a liquid space velocity from 0.01 to 10 volume parts Part by volume catalyst / hour fed in.

The method of the invention k-.nn in the most diverse Devices which are suitable for catalytic vapor phase reactions are carried out. It can e.g. B. fixed bed, fluidized bed or fluidized bed devices can be used.

The process of the invention can be carried out at normal pressure or at elevated pressures. However, if the pressure is too high, olefin formation is suppressed. One should therefore work at relatively low pressures (below 30 kg / cm ² ).

To regenerate the catalyst used according to the invention, a catalyst containing free oxygen is used Gas, such as air, is passed through the catalyst layer to burn off the free carbon deposited thereon.

The examples illustrate the invention.

example 1

20 g of a commercially available active alumina, consisting of amorphous particles having a particle size of about 1.65 to about 2.36 mm, _o Magnesiumsilikofluoridhexahydrat aqueous solution are immersed in 100 ml of 35 ° / and left for 36 hours at room temperature in . The aluminum oxide is then dried at 95 to 100.degree. C. and then calcined at 500.degree. C. for 3 hours.

The catalyst obtained in this way (fluorine content = about 2%) is introduced into a reactor of the fixed bed type. Subsequently, a mixture of C ₉ aromatics obtained from a reformate with a boiling range above 148 ^° C. at 550 ° C. and an excess pressure of 19 kg / cm ² with a liquid space velocity of 0.5 part by volume / part by volume of catalyst / hour. together with hydrogen gas <10 MoI H ₂ / mol mixture) passed through the reactor.

Table I shows the compositions of the mixture of C ₉₊ aromatics used and the solution obtained. The starting material can e.g. B. 1-methyl-2-n-propylbenzene, 1-methyl-3-n-propylbenzene, 1-methyl-4-n-propylbenzene, 1,2-diethylbenzene.

1,3-diethylbenzene, 1,4-diethylbenzene, n-butylbenzene, 1,3-dimethyl-5-ethylbenzene. 1 A- dimethyl-2-ethylbenzene, 1 ^ -dimethyl -'- äEhylbenzoI. I.2-dimethyl-3-ethylbenzene. Contains 1,3-dimethyl-2-ethylbenzene, 1,2-dimethyl-4-ethylbenzene, 1,2,4,5-tetramethylbenzene or 1,2,3,5-tetramethylbenzene.

Example 2

The attempt of example i is repeated. c. However, 20 g of a commercially available active aluminum oxide are immersed in 100 ml of 25% strength by weight aqueous 7iflksiiikofiuond-hexahydrate solution, and it // ird with a liquid space velocity of 0.25 part by volume, part by volume of catalyst / hour. worked. The fluorine content of the catalyst is about 1.5 V The ⁰ Frgebnisse are shown in Table I.

Bc 1> ο i e I 3

The request for example> repeats that

catalytic conversion is however at 600 C and with a liquid space velocity of 1.0 volume part / volume part Catalyst / hour. The results are shown in Table I.

Example 4

The experiment of example t is repeated that however, catalytic conversion is carried out at 470 ° C. The results can be seen from Table I.

2 04ö 556

Table I Parts, percent by weight

benzene

toluene

Xylenes (including ethylbenzene).

P-.opylbenzoI

Ethyl toluene

Triethylbenzenes

C _IO i aromatics

Exploit ° / ₀ d ° r Theo ·· -

Source material

2.7 21.3 36.4 39.6

example

I.

4.0

23.4
35. "

3.4
23.6

9.9
72.1

3.85
23.4
32.4

4.18
27.3

6.6
78.2

3.56 18.6 28.5

6.38 21.9 21.9 75.7

2.02 12.7 20.3

0.5 Ii.2 26.0 28.6 95.5

"c i s ρ i e I e 5 to 7

20 g de ^c A.uminiumoxids of Example 1 are dissolved in 100 ml of 3 _> ^ = -. "ILhtsprozentige aqueous MagnesiumsüikoPucrid hexahydrate solution immersed and left therein for 36 hours at room temperature Then the treated alumina obtained at the water bath is dried and then for 3 hours at 500 ⁰ C calcined.

The catalyst obtained in this way (fluorine content about 2.0 ° / ₀ ) is introduced into a reactor of the fixed bed type. A mixture of C ₉ f aromatics obtained from a reformate, the composition of which can be seen in Table II, is then fed ^{into this reactor at 550 ° C. and an excess pressure of 19 kg / cm 2} with a liquid space velocity of 0.5 volume / volume catalyst / hour . fed in.

Example 5 uses the vaporous starting material per N'oi with 10 MoI nitrogen gas and at Example 6 per Mon! diluted with 6C mol of hydrogen gas. The dilute, vaporous starting material is then fed into the reactor. For comparison, the reaction in Example 7 is carried out under the same conditions as in Example 5, however, there will be one in the Haiide! more available Silica-alumina catalyst used. From table !! are the results obtained after 30 minutes, 4 hours and 8 hours of reaction, respectively evident.

table

Composition of the liquid (proportions, percent by weight)

Loading Bcispic '

Time, hours
7 = I 8

Ί- I

Benzi «!

toluene

Ethylbenzene

Xylenes

n-propylbenzoI

p-ethyl toluene

m-Etnyhoiuoi

o-ethylitoluene

Mesilyls

Pseudocumene

Hrmimellithol and Indan

hazy (mainly C ₁₀ aromas).

5.1 14.8

5.3

7.3 31.0 10.6 21.3 25.1

0.8

19.1

23.1

14.0

1.4

14.1

32.0

4.3

23.8

1.0

16.4

0.14

1.3

2.8

0.57

5.3

23.8

10.5

8.8

4.1

22.1
1.2

17.2
0.10 1.3
2.9
0.7
5.3

24.0

10.8
8.7

Γ5.1

1.0

10.3

31.2

34.0

Examples 8-10

20 g of the aluminum oxide from Example I are stored in 50 ml 3 weight percent aqueous hydrogen fluoride solution for IX hours at room temperature. The aluminum oxide is then dried in a water bath and then calcined at 500 ° C. for ^{1 3 hours to remove the remaining volatile components.}

1.8 g of the catalyst obtained in this way (debris volume 10 ml) are placed in a quartz glass tube with an internal diameter of l ^ mm. the eip '* ii reactor \'"m I csthctiyp represents filled Subsequently, a 82 ° / ₀ aroma mineral hydrocarbons and the balance of paraffin-containing reformate hydrocarbons at 450 or 550 or 650 C (B <ISPN-l * '9 or . 10) and at normal pressure with em-'f IIusm, > m. -Space velocity .on 0.2 Volum'ctl Voluniieil K, ila! Ysator / h. fed into the reactor (ιΐι-κΐι. citi ^ hydrogen is introduced in a mixture with the <l; impffonni ^ c.1 charge with a Gcsehwindij wedge of (Hi '\ oi malliler / min shares of the reaction products ■■ "· ι · ■ ''''■>·" hydrocarbons were n 8 hours' ■ <It is determined to implement.

556

Table ff I

Fraction of άκ aromatic hydrocarbons, Gev / iehisproxent

BeU

tkmo '. ,,.,
ToitioJ
Äthyibetmn P-XyM .... m-Xyioi .... t> -Xy1oi Mesilylc Yscuooci Hemitj &
Other Cf
tnatsu ...

At the* ikl · 550 shotgun*
rhi 6.6 IS 3.3 2B / 0 12ß 17. « 7.3 3Y 4.0 18.2 !Oil US 6.1 5.5 5.3 5.7 4 _t l 4.5 7.5 7.7 ίί, Ο 2.7 3Y 3.6 12.5 47J 36.8

650

6.5

30.4

1.2

21 * 5

5.9 5.2 8.8 3.0

8.4

J 309 634/326

Claims (5)

Games for this polymethylbenzoie are pseudocumene patent claims: (i, 2,4-trimethylbenzoi) and durol (1,2,4,5-tetra-methylbenzoi) - these compounds are important 1. Process for the production of benzene. Toluene starting materials for the production of tri- and Pol> methylbenzenes by catalytic Krak- 5 mellitic acid or pyromellitic acid. no heavy aromatic hydrocarbons, numerous others, no polymethylbenzoic since it indicates that one of the constituent components of the aforementioned coal reformaf or a mixture of hydrogen sols sunk therefrom, such as alkyl aromatics with at least with a content of at least one alkyl 2 carbon atoms per alkyur group, have only a low remainder with at least 2 carbon atoms substituted aro- io utility value and moreover can only be extremely Malian hydrocarbons with at least difficult to separate from each other. 9 C-atoms (C ₃ , ^ - aromatics) in Dampffonn bd A well-known process for the utilization of the C ₉ * - be: elevated temperatures on a mainly aromatic compound in their hydroalkylation to benzene, a catalyst consisting of aluminum oxide with toluene and xyfolene. A fluorine content of 0.01 to 10% by weight, however, requires large amounts of hydrogen for this process. It's also done percent. a process known in which toluene and the C ₉ -. 2. The method according to claim I. characterized in that aromatics are redrawn with transalkylation to xylenes that are almost exclusively made from. In this process, however, the starting mixture consisting of _{C s aromatics mainly consumes expensive trimethylbenzenes.} Turns off. for these reasons, the C ₉ aromatics, especially 3. The method according to claim 'and 2. characterized in that the C ₃ different from polymethylbenzenes, - characterized in that a catalyst ver aromatics, so far not fully utilized,
wende *, which mainly consists of HF and, or Although it is still known. Cumene with KataWsa-BF-Lnd or SiF, uni or HBF. und.or gates from fluorinated aluminum oxide to benzene aozu-H ₂ SiF ₈ and or Nh ₄ F and or NH ₁ BF ₄ and '25 build (hydrodealkylation), but just OdCr (NH ₄ J ₂ SiF ₅ or mainly from none MgSaF obtained with ₆ and ₆ or ZnSiF se desired Polymethylbenzoie and CaSiF or ₆ loading the object of the invention was to provide a new method handeltem alumina. for the production of benzene, toluene and Polymetr ^ l- 4. The method according to claim ', characterized benzenes containing worthless C aromatics draws that a catalyst is used, the ao aromatic mixtures available 7u, in which additionally a proportion of 0.01 to 10 weight- the valuable polymethylbenzenes no L'mwand-BTozent, based on the catalyst, magnesium. treatment reaction or higher zinc. Contains silicon or boron. molecular products are newly formed. This 5. The method according to claim 1 to 4, characterized in that the object is achieved by the invention,
indicates that at temperatures of 400 35 the inventive method for the preparation up to 700 C, pressures of 1 to 30 kg / cm ² and with 'of benzene. Toluene and polymethylbenzenes by liquid space velocities of 0.01 to catalytic cracking of heavy aromatic carbons by volume. Starting material / part by volume of catalytic hydrogen. works and that the vaporous reformate or a mixture obtained therefrom with starting mixture previously substituted with more than double its content of at least one alkyl radical with th and up to about 60 times the amount of hydrogen, 2 carbon atoms aromatic thin. Hydrocarbons with at least 9 carbon atoms (C ₉ + aromatics) in vapor form at elevated temperatures over a catalyst consisting mainly of aluminum oxide with a fluorine content of 0.01 brings up to 10 percent by weight to implement. The components of the reaction product obtained in the process of the invention can easily through Distillation from each other. A reform In the known process / ur production ve π 5 ° mat contains, for example, a high proportion of the aromatic hydrocarbons, such as benzene, toluene , 5-trimethylbenzene). professionally from Reformati, ie by catalytic re Until now it was not possible, only the mesitylene vorr conveyors: from SChv / erbenzin obtained oil ge ^w on- Kpfnrmat ah7utrennen directly. since the latter has a high number of extracts and cracking petrol, ie due to the thermal content of 1-methyl-2-ethylbenzene, the boiling mixture of which is cracking oils obtained from heavy petrol, is only used by 0.5 "C from that of mesitylene. One from a reformate According to the process of the invention, aromatic hydrocarbon oil extracted from gasoline can be easily separated and utilized, however, containing mesitylene generally other than benzene, toluene and xyIo-, since the 1-methyl-2-ethylbenzene is cleaved and contains a high proportion of heavy aromatic 60 is separated from the C _{B +} aromatics. Since in the hydrocarbons. Among these heavy aromatics of the invention, aromatic compounds and propylene are also formed as by-products, this process ensures fertilization with at least 9 carbon atoms ( In the following, one of them is to be understood as "C ₉ " aromatics in comparison to the known processes en. To this outstanding utilization of the C ₉ -.- aromatics.
Many compounds belong to aromatics which, according to the process of the invention, are similar to the others in terms of their boiling point and other inherently lower aromatic hydrocarbons, benzene. Toluene and xylenes are enriched in these compounds will.
some polymethylbenzenes are very valuable. Special case- A special example of the alkyl aromas used in