DE1443493C - Process for the isomerization of terminal olefinic hydrocarbons - Google Patents

Description

The invention relates to a process for the isomerization of terminal olefinic hydrocarbons having 4 to 6 carbon atoms in the molecule, which are amenable to a shift in the double bond, in the presence of silicate catalysts at temperatures between 50 and 500 ° C, which is characterized in that the reaction in the presence of sepiolite with a surface area greater than 100 m ² / g, which has been freed from its alkali metal content, as a catalyst in the vapor phase with an hourly amount of liquid in the range from 0.1 to 10 V / V, preferably in the presence of inert diluent gases.

Preferably, the silicates serving as a catalyst are in one of the applied free metals essentially free form used. The catalysts are also expediently free from sodium in bound form and / or bound potassium.

The catalysts used are advantageously silicates which are obtained by using silicates which are in contain small amounts of bound sodium and / or bound potassium, a treatment subjects, by which this sodium and / or potassium is wholly or partially removed.

Sepiolite is used as a catalyst. Sepiolite is a commercially available clay mineral that occurs in nature and is also obtained synthetically can be. It has the ideal formula

H ₄ Mg ₉ Si ₁₂ O ₃₀ (OH) ₁₀ -OH ₂ O

and is also known as meerschaum. More information about sepiolite and its properties can be found in "Chemistry and Industry" of November 16, 1957, pp. 1492-1495.

Sepiolite contains small amounts of alkali metals, usually 1 to 2 percent by weight, which are bound in Form. These alkali metals are preferably removed by washing with mineral acid, strong organic acids, e.g. B. acetic acid, or with solutions of salts of these acids with nitrogenous Bases, e.g. B. ammonia, or with the free bases. In general it is necessary to use the Heat catalyst before use to remove nitrogenous bases.

For the inert diluting gas preferably used in the isomerization, one can use use, for example, nitrogen, the ratio preferably being in the range from 0.1 to 10 parts by volume of the diluent per part of the olefinic hydrocarbon.

The isomerization process of the invention is applicable to hydrocarbons which are capable of shifting the double bond. Possibly the feedstock may consist of a mixture containing at least one such hydrocarbon. When using mixtures lie of course the components are not in the equilibrium ratio required for the isomerization conditions is equivalent to. Depending on the isomerization conditions an isomerization can be brought about by shifting the double bond without changing the carbon structure.

The process according to the invention is particularly suitable for converting 4-methylpentene-l, 4-methylpentene- 2 and / or 2-methylpentene-1 into 2-methylpentene-2 and for converting 2-methylbutene-1 and / or 3 -Methylbutene-1 in.2-methylbutene-2 as well as suitable for converting pentene-1 into cis- and trans-pentene-2.
The process can be carried out under reduced pressure, normal pressure or elevated pressure.

In the prior art has been proposed for olefin isomerization, inter alia, with partial

ίο dehydrated zeolites (USA. - Patent 2 988 578) or with catalysts containing alkali metal (French patent specification 1 293 285) to work. The invention is characterized by the selection of a very effective and

• 5 at the same time inexpensive and easily accessible Catalyst material from. The catalyst according to the invention causes a shift in the Double bond without causing profound structural changes in the olefin used at the same time. The sepiolite catalyst according to the invention can be handled completely safely, while z. B. the alkali metal-containing catalysts of French Patent 1,293,285 work require under nitrogen and completely dry conditions while using relatively expensive reactor materials such as stainless steel autoclaves is necessary.

B e i s ρ i e 1 1

Using a microreactor, 4-methylpentene-1 was passed in the vapor phase at a space velocity of 1.0 at normal pressure over 1 cm of a powdered sepiolite bed. Four separate experiments were conducted at 150, 200, 300, and carried out 400 ⁰ C. The results obtained are shown in Table 1.

Table 1 ·

Composition of the product (percent by weight)

Unchanged input material

cis- and trans-4-methylpentene-2

2-methylpentene-l

2-methylpentene-2.

cis- and trans-3-methylpentene-2

2,3-dimethylbutene-2 ...

Reaction temperature ^{, 0 C}

150

28
2
6th

track
0

200

32

34

23

4th 0

300

28
13th
38

13th 0

Example 2

Using a microreactor, 4-methylpentene-1 was passed in the vapor phase at a temperature of 190 ^° C., a room flow velocity of 2 and under normal pressure over 1 cm ^{3 of} a pulverized sepiolite bed.

The analysis of the products at three different times during the experiment is shown in Table 2 listed.

Table 2
Composition 'of the products

(Weight percent)

Unchanged input material
cis- and trans-4-methylpentene-2

2-methylpentene-l

2-methylpentene-2

cis- and trans-3-methylpentene-2

Duration. Minutes

42

60 31

2 7 0

197

61 31

2 6

387

64

30th

'4

B e i s ρ ie 13

10 cm ³ "a powdered sepiolite were extracted with a 50% aqueous acetic acid solution under reflux. Thereafter, the Sepiolithi was washed with distilled water, ⁰ C and 2 hours at 350 ⁰ C dried for 2 hours at HO.

4-MethyIpenten-l was passed at a space velocity of 2, at atmospheric pressure and a temperature of 190 ⁰ C over 1 cm ³ of ^the catalyst bed.

The analysis of the product after a running time of 120 minutes is shown in Table 3.

Table 3

Composition of the product Weight percent Unchanged input material. . 36 cis- and trans-4-methylpentene-2 40 2-methylpentene-l 6th 2-methylpentene-2 15th cis- and trans-3-methylpentene-2 3

treated material was washed with deionized water and exhaustively extracted in a Soxhlet apparatus for 6 hours. Then, it was in an oven overnight at 110 ⁰ C and then to remove the ammonia for an additional hour BE ^ 35O ° C in a nitrogen atom dried.

Then, the activity was l-cm ³ sample of this material for the isomerization of 4-methylpentene-1 at 190 ⁰ C, a space velocity of 2 and an atmospheric pressure measured.

The composition of the product after a running time of 120 minutes is given in Table 4.

Table 4

Composition of the product *

Unchanged input material

4-methylpentene-2

2-methylpentene-l

2-methylpentene-2

3-methylpene-2

Weight percent

Example 4

A fresh 10 cm ³ sample of a sepiolite was ^{treated with 100 cm 3 of} an approximately molar aqueous ammonium acetate solution by percolation. The

Claims (2)

Claims: 48 36 4 12 1. A process for the isomerization of terminal olefinic hydrocarbons having 4 to 6 carbon atoms in the molecule, which are amenable to a shift of the double bond, in the presence of silicate catalysts at temperatures between 50 and 500 ⁰ C, characterized in that the reaction is carried out in the presence of Sepiolite with a surface area greater than 100 m ² / g, which has been freed from its alkali metal content, is used as a catalyst in the vapor phase with an hourly amount of liquid in the range from 0.1 to 10 V / V, preferably in the presence of inert diluting gases. 2. The method according to claim 1, characterized in that that the reaction in the presence of 0.1 to 10 parts by volume of the diluting gas per part of olefinic hydrocarbon performs.