DE1261493B - Process for the chlorination or bromination of hydrocarbons - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

int. Cl .:

C07c

German class: 12 ο -2/01

Number: 1 261493

File number: B 70938IV b / 12 ο

Filing date: March 1, 1963

Open date: February 22, 1968

The invention relates to a process for the chlorination or bromination of hydrocarbons, which is characterized in that n-alkanes having 4 to 20 carbon atoms or mixtures thereof are reacted with chlorine or bromine in the vapor phase, a catalyst being used which is produced by reacting a) refractory oxides of III. to V. Group of the periodic table or mixtures thereof or mixtures of a platinum group metal and aluminum oxide with b) compounds of the formula CCl ₂ XY, in which X and Y can be identical or different and are H, CI, Br, F or SCl or in X and Y together are 0 or S, has been prepared at 149-593 ⁰ C under non-reducing conditions prior to installation of 1 to 15 weight percent halogen, based on the used inorganic oxide.

As halogenatable inorganic oxides, for. B. the oxides of aluminum, boron, silicon, Titans or zirconia used. Of the refractory oxides, aluminum oxide is preferred. Possibly Mixtures of two or more inorganic oxides can also be used.

If alumina is used to make the catalyst it will preferably contain some Hydrogen. This is a characteristic of activated aluminum oxides, which are predominantly made of aluminum oxide exist, but also a small amount of hydrogen, usually less than 1 percent by weight contain. It is generally believed that this hydrogen is in the form of surface hydroxyl groups is present, and it is believed that the halogen compound in the Alumina in the places of at least some of the original acidic surface hydroxyl groups is introduced to form the active catalyst sites.

Any forms of alumina suitable as supports for reforming catalysts can be used. However, a form derived from an aluminum oxide hydrate precursor in which the trihydrate predominates is particularly preferred. An aluminum oxide form which contains a larger proportion of ß-aluminum oxide trihydrate is particularly suitable. The aluminum oxide can be easily obtained by hydrolysis of an aluminum alcoholate, e.g. B. aluminum isopropoxide, in an inert hydrocarbon solvent, e.g. B. Benzene, produce. All other things being equal, the greater the amount of halogen taken up by the aluminum oxide, the higher the activity of the catalyst, and since the maximum amount of halogen that can be added is a process for chlorination or bromination
of hydrocarbons

Applicant:

The British Petroleum Company Limited,

London

Representative:

Dr.-Ing. A. v. Kreisler, Dr.-Ing. K. Schönwald,

Dr.-Ing. Th. Meyer

and DipL-Chem. Dr. rer. nat. J. F. Fues,

Patent Attorneys, 5000 Cologne 1, Deichmannhaus

Named as inventor:

Anthony George Goble,

John Vincent Fletcher,

Center, Sunbury-on-Thames, Middlesex

(Great Britain)

Claimed priority:

Great Britain March 2, 1962 (8167)

can, is related to the size of the surface, it is advantageous if the aluminum oxide has a large surface of, for example, more than 250 m ^s / g, preferably more than 300 m ² / g.

Appropriately, the halogenable inorganic oxide is before halogenation with an alkali or Alkaline earth metal salt of an organic acid treated under such conditions that alkali or Alkaline earth metal is retained by the oxide.

The exact way in which the addition of an alkali or alkaline earth metal changes the activity of the catalyst is not known with certainty, but it is believed that the metal cation enters into a bond with the inorganic oxide in some way. Preferably the oxide is therefore subjected to a treatment after the addition, by which the alkali or Alkaline earth metal compound is decomposed, for example, calcination, and preferably compounds which can be decomposed without leaving other elements on the oxide.

809 503/335

3 4

stay. Particularly suitable compounds are salts. Nevertheless, she proved suitable and

of carboxylic acids, e.g. B. formates, acetates and oxa has advantages over other fluorinating compounds

late. The alkali or alkaline earth metal compound can have bonds.

the inorganic oxide in a simple manner by To prepare the catalyst, the Tempe-impregnation using a solution of 5 temperature, the duration of treatment and the amount of

Compound can be added. halogen-containing compound chosen so that the

The retained alkali or alkaline earth amount of halogen uptake at least 1% and not more than

may be 15 percent by weight in relation to the amount of the inorganic. Since the halogenation in the

Oxide to be small and in the range of 0.01 to 10 ° / ₀ of the essentially a surface phenomenon, is the weight of the inorganic oxide are. The io is the amount of halogen that is produced without the formation of free

Minimum amount that can be deposited in any given application of halogen, for the size of the

Purpose is required to selectively the catalyst surface area of the catalyst in relation, the

to make can be determined experimentally. Amount of halogen that does not produce free halogen

The metal that is present in excess of the minimum quantity will be kani ^ jum. jo_larger_istj the bigger

is not disadvantageous. It was found that the surface was raised. It is usually at least

The amount of halogen borrowed by oxides absorbed half the amount without the formation of free

the alkali metal in amounts of halogen could have been attached if the

for example 4 percent by weight or more. Catalyst with an alkali or alkaline earth

The production of the Totalysa metal according to the invention would have been dealt with.

gates, which is not under patent protection here, 20 The non-reducing agents used for halogenation

Will be in essentially the same way- traversing conditions can be inert or oxy-

out as they are in the German interpretative writing conditions. Preferred are the

1194 378 of the inventor. The latter are suitable as they lead to catalysts during

Compounds with the required structural formula of the chlorine-

are 25 tion or bromination more slowly lose their activity.

Carbon tetrachloride (CCl ₄ ),. ^N * ^ch ™ simple method is the treatment

of the metal oxide made by a gaseous

Chloroform (CHCl ₃ ), stream of halogen compound either alone or

Methylene chloride (CH ₂ Cl ₂ ), 3o preferably in a non-reducing carrier gas

τ- »· 1.1 jJ ₃ 4.1. ιγ ^ γ ^ λ τ-% is passed over "the metal oxide. Suitable carrier

Dichlorodifluoromethane (CCl ₂ F _{2) gas are} i _{SW Step Example} ei _S e nitrogen, air and oxygen.

Trichlorobromomethane (CCl ₃ Br), The temperatures used for halogenation

- Thiocarbonyltetrachlorid _(CCl3 SCl) ^Koen ° ^en pockets 149 and 593 ° C Hegen. In the event of

35 The turn of aluminum oxide takes away the inclination

Phosgene (COCl ₂ ), _to form free aluminum halide with the

Thiophosgene (CSCl ₂ ). Temperature too, so that when applying the higher

Temperatures in the range mentioned must be worked with caution. Since the temperatures used

Preferred of the listed compounds are normally the first three temperatures above volatilization. In the case of compounds which are at the temperature of the aluminum halide, the besides chlorine, carbon and hydrogen, other formation of free aluminum halide easily occurs Containing elements, these may be added to its appearance in the gaseous reaction attached to the catalyst for chlorine. products recognizable. When treating kata-For example has a treatment with dichloro- 45 lysers that consist of a. Platinum group metal and difluoromethane means that both chlorine and aluminum oxide are present, care must also be taken Fluorine is taken up by the catalyst. That the formation of volatile platinum complexes is present this prevents other elements from being adversely affected. The tendency to form such not the activity conferred by the chlorine, complexes can also become with increasing temperature however, introduce other properties, so that by 50 stronger. When treating catalysts that Appropriate care must be taken to ensure that a platinum group metal and aluminum oxide the selectivity of the catalyst is not adversely affected, the temperature is preferably 139 to will. Small amounts of halogen (including chlorine) 371 ° C, the combination being platinum on aluminum furthermore, even before the chlorination treatment, oxide, in particular at 232 to 316 ° C., and the combination Catalyst be present without the nation palladium on alumina at 260 to 55 activity imparted by chlorination is treated at 343 ° C. The chlorination reaction is is pregnant. Thus, according to the process, this can be exothermic and the temperatures indicated Inorganic oxide subject to the invention at the initial temperatures used. Be platinum-alumina catalyst, which is up to The speed of supply of the halogen

Contains 1 percent by weight of halogen, as normal - the compound is preferably as low as possible, wise for reforming gasoline to ensure uniform halogenation and boiling hydrocarbons is used. a rapid rise in temperature as a result of

Suitable fluorinating compounds are, for example, to avoid exothermic reactions, like methylene fluoride, fluoroform and tetrafluor- Preferably the addition is not more than 1.3

. carbon. The last-mentioned weight percent halogen compound per minute bond is preferred. Tetrafluorocarbon is an extremely stable attracted to the catalyst. When using a Connection, which at first glance does not appear to be the carrier gas, is the flow velocity Production of fluorine-containing catalysts choose preferably at least 200 V / V / h. Suitable is

here a range from 200 to 1000 V / V / hour. It is preferred to work at normal pressure.

The active catalyst is subject to hydrolysis in the presence of water. He must therefore under stored in anhydrous conditions. The same must be used for the catalyst production Materials to be anhydrous.

The process is particularly suitable for the chlorination and bromination of hydrocarbon mixtures which obtained from petroleum fractions or gas oil fractions from petroleum, e.g. B. of normal hydrocarbon fractions, obtained by separation processes using molecular sieves.

The feed is passed over the catalyst in the vapor phase. The reaction temperatures are expediently in the range from 20 to 150 ° C, but can also be at higher or lower temperatures to be worked. Underpressure, normal pressure or overpressure can be used.

For the production of monohalogenated hydrocarbons, the process is preferably carried out in Presence of an excess of the hydrocarbon over that required to produce these compounds carried out stoichiometric amount.

The process is particularly suitable for the chlorination of normal paraffins having a carbon number in the range from C ₆ to C ₁₅ for the purpose of producing halogenated hydrocarbons for use in the production of alkylate suitable as a washing raw material.

example 1

40 cm ^{3 of} a commercially available aluminum oxide were calcined at 500 ° C. for 1 hour and then divided into two equal parts. One part is referred to as Catalyst A.

The other part of the calcined alumina was at 300 ° C with a stream of dry nitrogen reacted, which was saturated with carbon tetrachloride at room temperature, with a chlorinated Catalyst with a chlorine content of 12.0 percent by weight was obtained. This material is presented below referred to as catalyst B.

Each catalyst sample was placed in ^{standing reactors in an amount of 20 cm 3} , which were kept at an initial temperature of 80 ° C. Then a mixture of dry nitrogen and chlorine gas at normal pressure and a flow rate of 150 cm ³ / min. passed through. Now n-heptane was added in an amount of 1.0 V / V / hour. (calculated as a liquid) introduced, the chlorine content of the gas mixture used being regulated so that the molar ratio of chlorine to n-heptane was about 1.0: 1.0.

After an initial rise in temperature, the catalyst bed was at temperatures in the range of Maintained 100 to 120 ° C and the total liquid product collected separately for each individual hour of the running time.

The results of the analysis (gas-liquid chromatography) of typical samples of the liquid product, the one with the untreated aluminum oxide (catalyst A) and the chlorinated aluminum oxide (Catalyst B) are shown in Table 1. The advantage of the chlorination treatment of the catalyst is both higher activity and selectivity.

Table 1

catalyst B. A. Section of the experiment, 8th to 9th hour 6th to 7th 120 to 121 Temperature, ⁰ C 121 Liquid product extraction,, 97.2 Weight percent 88.7 Gas-liquid Chromatography C ₇ fraction (does not contain converted n-heptane) 54.8 Weight percent 73 Monochloroheptane fraction, 35.6 Weight percent 11.2 Di- and polychlorheptane 9.6 fraction, percent by weight 15.8 Molar ratio of mono- chlorinated to polychlorinated 3.7: 1 th products 0.7: 1

A further analysis of the monochlorheptane fraction produced the results shown in Table 2.

Table 2

1-chloroheptane 17.2%

2-chloroheptane * 41.4%

3-chloroheptane * 27.3%

4-chloroheptane * 14.1%

* Provisionally referred to as 2-, 3- and 4-isomers.

Example 2

20 cm ^{3 of} a commercially available platinum-aluminum oxide catalyst containing 0.58 percent by weight of platinum and 0.8 percent by weight of chlorine were treated with an aqueous potassium acetate solution in such a way that the catalyst, after drying at 120 ° C. to constant weight and calcining for 1 hour, with 500 ⁰ C had a potassium content of 2.3 percent by weight.

The catalyst was then ^{reacted at 300 °} C. with a stream of dry nitrogen which was saturated with carbon tetrachloride at room temperature. A chlorinated catalyst with a chlorine content of 6.3 percent by weight was contained. This catalyst was used for the chlorination of n-heptane in the manner described in Example 1.

A typical analysis of the liquid product obtained is shown in Table 3.

Table 3

Running time 9 to 10 hours

Temperature 122 to 125 ° C

Liquid product recovery 98.5 percent by weight

Composition of the liquid product

C ₇ fraction 64.3 percent by weight

Monochlorheptane fraction .. 27.5 percent by weight

Di- and polychlorheptane 8.2 percent by weight

fraction 8.2 percent by weight

Molar ratio of mono-

chlorinated to polychlorinated

th products 3.4: 1

Example 3

A commercially available platinum-alumina catalyst containing 0.58 percent by weight platinum and 0.8 percent by weight Containing chlorine, was in the manner described in Example 1 at 300 ° C with carbon tetrachloride vapors treated. The chlorinated catalyst obtained contained 12.8 percent by weight of chlorine.

This material was used as a catalyst for the reaction of η-hexane with a chlorine-nitrogen gas mixture (Molar ratio 1: 2) used at normal pressure. The space velocity of the η-hexane (calculated as liquid) was 0.35V / V / h. The chlorine input was kept at about 1.0 mole per 0.75 mole of η-hexane. At reaction temperatures in Range of 40 to 50 ° C became the liquid product formed by the 8th to 12th hour of the test period collected and separated into the following fractions by distillation:

Q-hydrocarbons (90% unchanged n-hexane,
10% hexenes) 20 percent by weight

Monochlorhexane 52 percent by weight

Polychlorhexane 28 percent by weight

The analysis of the Monochlorhexanfraktion by gas-liquid chromatography showed that it consisted of 18 ° / ₀ of 1-chlorohexane. This was confirmed by nuclear magnetic resonance analysis, which indicated that the remainder consisted of a mixture of 2- and 3-chlorohexane.

Claims (4)

Patent claims: 1. A process for the chlorination or bromination of hydrocarbons, characterized in that n-alkanes having 4 to 20 carbon atoms or mixtures thereof are reacted with chlorine or bromine in the vapor phase, a catalyst being used which is produced by the reaction of a) refractory oxides III. to V. Group of the Periodic Table or mixtures thereof or mixtures of a platinum group metal and aluminum oxide with b) compounds of the formula CCl ₂ XY, in which X and Y can be identical or different and are H, Cl, Br, F or SCl or in X and Y together are O or S, has been prepared at 149-593 ⁰ C under non-reducing conditions prior to installation of 1 to 15 weight percent halogen, based on the used inorganic oxide. 2. The method according to claim 1, characterized in that the catalysts used have been produced from refractory oxides with a surface area of more than 250 m ^a / g. 3. Process according to Claims 1 and 2, characterized in that the catalysts used from refractory oxides that have been prepared prior to reacting with the above Halogen compound impregnated with alkali or alkaline earth salts of organic acids and calcined have been, so that the inorganic oxides 0.01 to 10 percent by weight, based on her Weight, contained in alkali or alkaline earth metal. 4. Process according to claims 1 to 3, characterized in that one carries out the implementation of the above-mentioned n-alkanes with chlorine or bromine at 20 to 15O ⁰ C. 809 509/335 2.68 © Bundesdruckerei Berlin