DE2209442C3 - Use of GraphH alkali metal intercalation compounds for the hydrodekylation of alkyl aromatics - Google Patents

Description

The dealkylation of alkyl aromatics in the presence of various catalysts is known.

The invention relates to the use of graphite-alkali metal inclusion compounds a weight ratio of the alkali metal to graphite of 0.1 to 10: 1, especially from 0.5 to 2: 1, the optionally also a transition metal compound from group VIII of the periodic table in a weight ratio to graphite from 0.001 to 10: 1, preferably from 0.01 to 0.5: 1, as catalysts for the Hydroentalkyiation of alkyl aromatics.

Are graphite-alkali metal intercalation compounds already from Advances in Inorganic Chemistry and Radiochemistry. Volume 1. 1959. Pages 236 and 255 and Applied Chemie, 71st year 1959, no. 15/17. Page 487 and 488 known. However, these publications can use such intercalation compounds as Catalysts are not removed in the hydrodalkyiation of alkylaromatics.

When graphite-alkali metal intercalation compounds are used according to the invention, hardly any carbon is deposited on the surface of the catalyst in the hydrodalkyiation of alkylaromatics. The catalyst is to a high degree against catalyst poisons, such as carbon dioxide. Carbon monoxide, sulfur compounds, ζ. Β. Tiophene resistant. Under suitable reaction conditions, such as the ratio of hydrogen to alkyl aromatic compound, reaction temperature. Pressure and flow rate of the alkyl aromatic compounds, the catalyst causes the selective formation of Ar - C _n - iH2n - i from Ar _{- C n} Hj _n * 1. Where Ar is an aromatic radical. Furthermore, the decrease in the activity of the catalyst, caused by the polymerization of alkylbenzene. can be prevented by pretreating the same with hydrogen and ammonia and adding aluminum oxide powder to the catalyst. This gives the catalyst a high level of activity and a long service life.

The alkali metal serves as an electron donor and graphite as an electron acceptor. Of the transition metal compounds the halides, oxides and / or sulfides can be used. Of these, dip Halides preferred.

The catalyst can be prepared in the following ways:

1. Subjecting a mixture of graphite and an alkali metal under reduced pressure, e.g. B. at 10 ~ ³ cm Hg, or in an inert gas atmosphere of He, N2 or Ar, a heat treatment at temperatures of 150 to 350 ° C.

2. A graphite-alkali metal insert is formed

Ruügsverbindungen by subjecting a mixture of graphite and the transition metal compound from group VIII of the periodic table to a heat treatment at temperatures of 250 to 500 ⁰ C under reduced pressure in an inert gas atmosphere, then adding the alkali metal to the graphite transition metal compound thus obtained and the resulting product at reduced pressure or in an inert gas atmosphere, e.g. B. under argon and nitrogen, heated at a temperature above the melting point of the alkali metals. The catalyst prepared in this way has a weight ratio of transition metal compound to graphite of 0.001 to 10: 1, preferably 0.01 to 0.5: 1. The weight ratio of the alkali metal to the graphite transition metal compound is generally 0.1 to 10: 1. preferably 0.5 to 1: 1. The graphite-alkali metal intercalation compound has a weight ratio of the alkali metal / graphite of 0.1 to 10:! Preferably 0.5 to 2: 1. The graphite used for the production of the catalyst can be obtained by pyrolysis of carbonaceous material, preferably by pyrolysis of activated carbon , are obtained. Graphite in the graphitization state. which can be 100% can be used without further ado. Partially graphitized carbonaceous material above the graphitization state, which can be 10%, can also be used.

When performing the Hydroentalkyiierung z. B. a gas mixture of alkylbenzene and hydrogen at normal pressure or above atmospheric pressure and a temperature of 250 to 400 C in one Introduced a flow reactor with a fixed bed, the catalyst having been introduced at room temperature was. The alkylbenzenes introduced became benzene. Alkylbenzene with fewer carbon atoms than that used Ronmatenal and methane degraded. The yield of those formed in the hydrodalkyiation Products was about 90% of the theoretical value in the process according to the invention.

example 1

Graphite produced by graphitizing activated carbon. and potassium were added in a graphite to potassium weight ratio of 2: 1 to a U-shaped flow reactor made of glass with a fixed bed and heated to 300 to 35OX for 20 hours under reduced pressure. A gold-colored graphite-potassium intercalation compound (C ₈ K) was formed. A deep blue C ^ tK intercalation compound was obtained by reacting 5 parts of graphite with 1 part of potassium at 350.degree. The surface area of the catalyst was determined by the BET method. It was 20 m ² / g. In the BET method developed by Brunauer, Emmett and Teller in 1938, the surface area of the catalyst is determined from the adsorption isotherm, using nitrogen gas at its condensation temperature.

A gaseous mixture of ethylbenzene, toluene and hydrogen was with a space velocity (SV) from 760 to 950 ml / ml of catalyst per hour at the temperatures indicated in Table 1 through the reactor passed in the circuit that had been charged with the catalyst prepared above. The different Grain sizes of the graphite are also given in Table 1. After that, the products were in a

Lt.

Dry ice-methanol trap collected. The quantitative composition was determined using gas chromatography determined The results are shown in Table 1. Most of the not in the Dry ice-methanol trap condensable products 5 found

Table 1

was methane. A decrease in the activity of the catalyst, which affects the life of the catalyst could not have an adverse effect even after ten continuous attempts

catalyst
(Grain size)

Hj / ethyl benzene *)

Reaction temperature

(Molar ratio) (C)

Room sales

speed (one-time
Passage)

(ml / ml (%)

catalyst

per hour) Product composition **} (mol%)

94/6 350 94/6 340 92/8 300 94/6 350

QK (1200 α)
C ₈ K (4700 μ)
C ₈ K (1200 μ)

Q ₄ K (1200 μ)

* | The total pressure was 1 atmosphere. **) The gas phase components were methane and ethane.

Example 2

Ei> were catalysts according to the procedure given below in a U-shaped flow reactor made of glass with a fixed bed. A hydrodemethylation of toluene was carried out.

The graphite used to manufacture the catalyst had a grain size of 1200 μ to 4700 μ. It was made by graphitizing activated carbon. The degree of graphitization of the on this Graphite produced in this way was examined with the aid of X-ray spectroscopy. The degree of graphitization was 30 to 90%. The graphite-alkali metal intercalation compound was obtained by heating a Mixture of granulated graphite of various grain sizes and alkali metals, e.g. B. Potassium or Sodium, produced under reduced pressure at temperatures from 300 to 350 ° C.

A catalyst made from a graphite-potassium intercalation compound with a transition metal compound was made by first adding graphite to the

Table 2

950 760 770 950

4.3
4.0
1.2
5.7

42
35
22nd
38

58 65 78 62

different transition metal compounds was mixed, with the weight ratio of the graphite increasing the transition metal compounds was about 1: 0.1.

Then the mixture was heated ^{to 350 °} C. under reduced pressure in a closed tube. Potassium was then added, a weight ratio of potassium to graphite of 1: 1 being maintained. The resulting mixture was

heated and melted at temperatures of 300 to 350 ⁰ C. A gas mixture of toluene and hydrogen was at a space velocity SV of about 1000 ml / ml of catalyst per hour at the temperatures given in Table 2 over the catalyst

sator circulated. Thereafter, the products were collected in a dry ice-methanol and the case of quantitative analysis by gas chromatography chromatography (Apiezon L column temperature 80 to 9O ⁰ C). The results obtained are in Table 2

reproduced. Most of the non-condensable material in the trap was methane.

catalyst
(Parts by weight)

Graphite-K (5-4)

(Graphite: 4700 μ)

Graphite-K (5-5)

(Graphite: 1200 μ)

Graphil-FeCb-K

(5-0.5-3)

Graphite-NiCb-K

(5-0.5-5)

Graphite-CoCb-K

(5-0.5-5)

Graphite-RuCb-K

(5-0.5-5)

Graphite Na

(5-4)

hh / ethyl
benzene Reaction
temperature (Mol-
Ratio) ( ⁰ CI 91/9 350 94/6
94/6
94/7 350
400
400 94/6 400 94/7 350 94/8 400 94/6 400

Room sales

speed- (one-time

speed passage)

(ml / ml catalyst / hour)

790

760
760
760

790
760
760
770

15.8

3.5 12.5 17.0

20.1 9.8

17.7 9.2

continuation

catalyst Ha / ethyl Reaction space sales volume benzene temperature speed (unique age Passage) {Parts by weight) (Mol- CC) (ml / ml cat- (%) Ratio) analyzer / hour)

Graphite FeCla Na 94/6

(5-1-5)

Graphite-Rb 94/6

(2-1)

Example 3

Following the procedures of Example 2, catalysts were prepared. They were placed in a flow reactor init fixed bed given. A gaseous mixture of various Aikylbenzenes and hydrogen was on implemented these catalysts. The space velocity (SV) of the gaseous mixture was about 10,000 ml / ml catalyst per hour and the

Table 3

400 350 760
760

15.1
4.6

Liquid hourly space velocity, ₅ (LHSV) 1 ml / ml catalyst per hour. The temperature was adjusted to 400 ° C and the pressure to 40 atmospheres. The composition of the oily products, which had been collected by condensation in a cold trap, was determined with the aid of gas chromatography. Table 3 shows the results of the hydrodetalkylation of the various alkylbenzenes.

Catalyst H ^ Alkylbenzene Pressure Flow Reaction Oil Yield Product Composition

speed temperature conversion

(by weight parts) (molar ratio) {atm.) (ml / ml PC) (%) (MoI-V ₀ )

Catalyst / hour)

Graphite-K »)
C ₈ K (10)

Hj / ethylbenzene = 90/10 40 (SV) = 10000

(76)

CH ₃

oö

40% 60%

C ₈ K (10)

Hj / methylbenzene = 95/5 40 (LHSV) = 1.0

(86)

90%

C ₈ K (10)

C ₈ K (00)

Hj / xylene mixture = 90/10 40 = 1.0

H ₂ / cumene = 90: 7 40 = 1.0

60

92

62% 38%

CH ₃ C ₂ H ₅

o 6 6

20% 32% 42%

Graphite-FcClj-K (5-1-4) H ₂ / Ethylbenzene = 90/10 40 = 1.0

90

*) The graphite used was grainy throughout. The grain size was 1200 μ. The graphite itself was made by graphitizing activated carbon manufactured

Example 4

The catalyst was prepared according to the procedure of Example 1. It was placed in a flow reactor with a fixed bed. In him the Hydroentalkylation of n-propylbenzene on the same

Table 4

Catalyst')

H ₂ (SV) in ml / ml catalyst / hour

Flow rate n-propylbenzene (LHSV) ml / ml catalyst / hour

Way carried out as in Example 1 at normal pressure.

The collected) »products placed in a dry ice-methanol trap had been condensed; were determined with the aid of gas chromatography. The-received Products are shown in Table 4.

Reaction temperature

Sales product composition

CH, CH ₂ CH ₃

QK (1200 μ) 1200 0.4

QK (1200 μ) 1200 0.4

QK (1200 μ) 600 0.2

QK (1200 μ) 2900 0.8

* The catalyst consists of 5 g graphite and 4 g potassium

example

8.1 1 49 50 4.2 2 58 40 17.1 3 46 51 6.0 3 47 50

On a catalyst which had been prepared according to the method of Example 1. became the hydrodealkylation carried out by isopropylbenzene at normal pressure. The products were made by condensing

Table 5

collected in a dry ice-methanol trap. They were quantified using gas chromatography examined. The results are shown in Table 5.

KaiaKsator *)

H ₂ (SV) in ml'ml flow reaction

Catalyst hour speed temperature n-propylbenzene (LHSV) in ml / ml Kaialvsator / hour (C)

Sales product composition

(Mon! - ⁰ /.!

1200 0.4 400 3.7 Λ CH, CH ₂ CH, 1200 0.4 350 4.6 V Λ Λ 600 O.- " ¹ 350 4.5 20th ¹ V QK (1200 ^) 600 0.2 400 11.8 15th 53 27 QK (120OuI 33 55 30th QK (12 (X) JLi 31 23 44 QK (1200 x) 27 42

The catalyst contains 5 ε Ciraphii and 4 g potassium

Example 6

Lake Penu! Benzene and hydrogen were flowing at flow rates of sec-pemylbenzene (LHSV) of 0.29 mlml of catalyst per hour and of Hydrogen (SV) from 860 ml ml of catalyst per hour at a temperature of 400 C over a catalyst circulated according to the procedure of Example 1 had been prepared. The benzene was then toluene H \ droemalk \ lation of sec-pentylbenzene carried out The products collected by condensation in a dry ice-methanol trap became the quanti-

tat'ven analysis using gas chromatography. In Table 6 are the selectivity values specified. The conversion was 7.1%. A 6c graphite with a grain size of 4700 u was used.

Table b
Selectivity (° / o)

Ethylbenzene

Isopropyl
benzene

Sec -Butyl ■
benzene

3.0

25th

20.b

50

inn a / ΠΑ

ίο

B e i s ρ i e 1 7,

The hydrodealkylation of butylbenzenes was obtained products were quantitatively investigated / The dhf dhdl ' ] \ Τ

at an i ^ aiaiys aior aurc ngeiunri, u he nacn uc Hj (SV) Flow React geonisse; »Main ι a new / compiled, - ?; » ■ * ■ * Product composition Procedure by Bei mi ct in speed functional (Mol%) Table 7 game 1 was made. the age tempe- sales volume benzene toluene Source material Kataly Butyl rature Ethyl- n- lso ~ sator *) benzene benzene propyl propyl (LHSV) in benzene benzene (ml / ml (ml / ml ( ⁰ C) KatVStd.) Purchase hour) 1200 0.4 400 ■ (%) 36.4 - - 1200 0.4 400 1.54 9.7 53.9 - 21.6 - n-butylbenzene CsK 1200 µ 1200 0.4 400 6.9 2.3 76.1 75.5-19.5 Isobutylbenzene CsK 1200u 1200 0.4 400 8.8 4.3 0.7 22.1 - - Sec-butylbenzene CsK * 120Ou 600 0.2 400 1.6 33.7 44.2 30.1 - - tert-butylbenzene CsK 1200 µ 600 0.2 400 3.02 11.7 52.0 3.1 31.3 - n-butylbenzene CaK 470Ou 600 0.2 400 26.4 5.8 50.0 68.6-23.0 Isobutylbenzene CsK 4700 µ 600 0.2 400 22.9 5.4 3.0 50.6 - - Sec-butylbenzene CsK ' 470Ou 14.0 15.8 33.6 tert-butylbenzene CsK 470Ou

*) The catalyst contained 5 g graphite and 4 g potassium.

example

It was the hydroentalkyüerung of different had been. The products obtained were quantita-Cs-aromatic Hydrocarbons examined on a catalytic converter The results are shown in Table-8 Lysator carried out, the prepared according to Example 1 put together

Table 8

Starting material

Catalyst H ₂ (SV) in ml / ml flow reaction

(Grain size) KaWStd. speed temperature

Sales volume**)

1,2,3-trimethylbenzene QK (1200 ι) I, Z4-trimethylbenzene QK (120Ou) i, 3,5-trimethylbenzene QK (1200 u.) o-ethyltoluene QK (1200 μ) m-ethyltoluene QK (1200 μ) p-ethyltoluene QK (1200 μ) Gj distillation QK (4700 μ) Cq distillation QK *) *) Large pore radius, small Surface. *) Mole / mole (%).

1200

1200

1200

1200

1200

1200

600

600

ί 4-row (Tl (LHSV) in ml / ml
KatiStd. 0.4 400 0.4 400 0.4 400 0.4 400 0.4 400 0.4 400 0.14 400 0.14 400

20.1

14.2

8.3

3.5

8.2

5.6

11 I.

(Continuation)

Starting material Catalyst Benzene Toluene Product composition (mol%)

(grain)

Ethylbenzene o-xylene m-xylene p-xylo

1,2,3-methylbenzene 1,2,4-trimethylbenzene 1,3,5-trimethylbenzene o-ethyltoluene m-ethyltoluene p-ethyltoluene C ₉ distillation Cq distillation

C ₈ K 3.2 2.6 - 48.4 42.6 --- (1200 μ) C ₈ K - 4.9 - 16.0 12.5 66.7 (1200 μ) C ₈ K 3.8 12.5 - - 83.5 - (1200 μ) C ₈ K 14.5 78.1 7.4 - - (1200 μ) C ₈ K 1.7 20.9 22.0 - 55.4 - (1200 μ) C ₈ K 0.9 13.8 26.3 - - 59.0 (1200 μ) C ₈ K 11.6 25.2 4.4 11.1 19.2 28.4 (4700 μ) C ₈ K *) 6.1 30.1 3.7 20.2 21.0 18.9

Claims (1)

Claim: Use of graphite-alkali metal intercalation compounds with a weight ratio of the alkali metal to graphite from 0.1 to 10: 1, especially from 0.5 to 2: 1, the optionally also a transition metal compound of Group Viii of the Periodic Table in a weight ratio to Graphite from 0.001 to 10: 1, preferably from 0.01 to 0.5: 1, contained as catalysts for Hydroentalkyiation of alkyl aromatics.