DE1418681B - Process for the codimensioning of olefinic hydrocarbons - Google Patents

Description

I 418 681

1 .. -2. ■

The invention relates to a process for Codi- is generally between 1 and 20 weight merization of olefinic hydrocarbons with min- percent of the potassium compound, preferably between at least 3 carbon atoms in the molecule or 2 and 7 percent by weight, with 4 to 6 weight mixtures of such olefins with ethylene are particularly preferred when the percentage is increased.
Temperature and elevated pressure in the presence of a 5 An alkali metal potassium compound applied to a carrier substance, such as potassium carbonate or potassium catalyst, silicate, can advantageously be used as anhydrous compound.

British Patent 824,917 discloses a method. A preferred embodiment of the method

drive to the dimerization of propylene in the presence of the invention consists in the codimerization in

unit of an alkali metal catalyst at a temperature io presence of a dispersion of 4 to 6 weight

temperature between 38 and 204 ⁰ C and a pressure of percent sodium metal on anhydrous potassium

1 to 100 at. Carry out suitable alkali metal carbonate as a catalyst. ■■

are said to be lithium, sodium, potassium, rubidium and the codimerization of isobutene with ethylene

Include cesium. In the above, the ratio of the partial pressures of ethylene

Patent specification is also indicated that the alkali i ₃ to isobutene 1: 2 to 5: 1 (preferably about 1: 1)

metal as a film on an inert carrier. ? ,

can be applied and the use of If you codimerize isobutene and ethylene,

Potassium on powdered potassium carbonate is mentioned. can high yields of methyl pentenes !! achieved

It is the aim of the present invention to provide a solution. By selecting reaction

drive for codimerization of olefinic carbon 20 temperature and pressure high yields of 2-methyl

hydrogen with at least 3 carbon atoms in pentene-1 or 2-methylpentene-2 can be obtained.

Molecule or mixtures of such olefins with ethylene is usually a preformed catalyst with

in the presence of an improved alkali metal catalyst, olefinic hydrocarbons in contact

to create sators. brought. If the codimerization conditions

The process according to the invention is characterized in that the catalyst is formed in situ, characterized in that the codimerization can also be carried out with elemental sodium and a potassium temperature of 100 to 200 ° C. and a pressure connection with the olefinic hydrocarbon between atmospheric and 280 kg / cm ² , ge.

optionally in the presence of hydrogen or suitable starting materials are propylene, isobutylene,

a hydrogen-containing gas, in the presence of a butadiene and isoprene in combination with ethylene.

1 to 20 percent by weight of sodium metal on a «-olefins are the preferred starting materials,

anhydrous potassium, rubidium or cesium ver- There are temperatures in the range 100 ⁰ C

Bond-containing catalyst carries out, the applied to 200 ⁰ G. -

by dispersing molten sodium- Usually the reaction pressure is at least

metal at a temperature in the range 250 to 35 atmospheric pressure and can be up to 280 kg / cm ²

500 ° C at a pressure that is stable at this temperature. The pressure is preferably between

finely divided, anhydrous compound of potassium, 70 and 176 kg / cm ² excess pressure and in particular

Rubidium or Cesium, preferably in a pressure ^{between 98 and 130 kg / cm 2,}

inert gas atmosphere. Codimerization can be carried out in batches or continuously

Potassium-diluents are particularly suitable as carriers, and in the latter case

Bonds such as potassium hydroxide and potassium salts become space velocities between ^! 0.5 and

of mineral acids such as silicates, phosphates and 10 V / V / h preferred. The applied dimerization

Halides; potassium carbonate is preferred. '' 'conditions will be according to responsiveness

The catalyst can be obtained by mixing the olefinic compounds, the activity of the

molten sodium with an anhydrous potassium 45 catalyst system and the nature of the required

Connection to be established. Preferably the product is chosen.

Molten sodium with the potassium compound, if desired, can form the product again finely divided form vigorously stirred. Purpose of obtaining unreacted monomers distilled moderately, the potassium compound has a particle size, and these can be in the codimerization size less than 152 microns. Usually 5 ° is to be returned.

it is desirable to have a blanket of an inert gas, in case there is an increased yield of a given

z. Nitrogen, while isomeric mixing is desired, can be carried out in a known manner

is performed. an isomerization using one at the

The temperature at which the sodium reacts _{to the isomerization of olefinic C 6 hydrocarbons}

Potassium compound is not made of the usual catalyst,

outgoing. In general, it is necessary for suitable catalysts are silicon dioxide / aluminum

Temperatures closer to the melting point of the miniumoxide and '. natural tones that are ordinary

Sodium are to be stirred vigorously for longer than 150 to 300 ⁰ C used. Sodium or

if the elemental metal at higher tempe- potassium on aluminum oxide, which is usually at a

ratures is applied. However, to take account 60 temperature in the range -150 ⁰ C to above 150 ⁰ C,

ensure that the potassium compound does not decompose, preferably room temperature, are used,

that it does not melt or sinter. Supported phosphoric acid catalysts, e.g. B.

In general, the sodium metal in a phosphoric acid on pumice stone, which is at 150 to 300 ° C

Temperature, are preferably used at least 25O ⁰ C.

250 to 500 ° C, applied to the potassium compound, 65 In a preferred embodiment, the the potassium compound being selected accordingly codimerization in the presence of hydrogen, guided. Then the catalyst needs less frequently

The amount of elemental sodium used to be regenerated. Instead of hydrogen

you can also use a gas mixture which advantageously contains 70 mol percent hydrogen, for example a gas mixture consisting of 70 mole percent hydrogen and 30 mole percent methane. Other suitable gases are steam cracker off-gas, off-gas from a catalytic cracker, and off-gas produced by originates from the dehydrogenation of hydrocarbons.

The inventive method can in the presence of a normally gaseous paraffinic Hydrocarbon, such as methane, ethane or propane, are carried out. The usually gaseous one Paraffinic hydrocarbons can be added to the feed material before it enters the reactor or it can be fed to the reactor separately. The relative ratio of Codimerization feed to normally gaseous Paraffin vary within wide limits.

The process can also be carried out in either the presence or absence of a normally liquid solvent are executed. Preferred solvents are usually liquid paraffins, of which n-heptane is particularly suitable.

The invention is explained in more detail using the following example.

example

4 g of sodium metal with 100 cm ³ of anhydrous potassium carbonate of less than 152 micron particle size at 360 ⁰ C mixed mechanically. The catalyst was placed in a 11-making shaken autoclave of stainless steel and the system heated to 170 ⁰ C. Isobutene was introduced at a pressure of 67 kg / cm ² overpressure and then ethylene up to a total pressure of 105 kg / cm ² overpressure. The reaction was allowed to continue for 20 hours at the temperature of 170 ^° C., the pressure falling to 35 kg / cm ^{2 overpressure during this time.}

The products and condensable gases were collected in acetone / solid CO ₂ cold traps. The contents were allowed to warm to room temperature to remove volatiles up to and including C ₄ hydrocarbons. The residue was distilled in a column with 5 theoretical plates in order to obtain a 32 to 66 ° C. fraction which was analyzed by gas chromatography. This fraction constituted 70 percent by weight of the total normally liquid reaction products.

This product contained:

dimerized, the propylene feed rate being 1 volume of propylene per volume of catalyst per hour. The following results were obtained:

2-methylpentene-1 52.0 percent by weight

2-methylpentene-2 48.0 percent by weight

Maximum activity catalyst K / KüCOs 53 (Grams of witches per Na / K, CO ₃ 18th Hour per gram IO dispersed metal) .... 7.62 % Conversion of 9.58 per run 87 Propylene / catalyst 5 half-life (days) 15th 67 6th Analysis of the witches (after 50 0.5 4 days in electricity), 1 Weight percent 4-methylpentene-l 20th 4-methylpentene-2 .... 82 2-methylpentene-l 8th plus witches-1 2-methylpentene-2 7th Witches-2 and -3 1 25th 1.5

50

55

The particular advantages of using sodium over anhydrous potassium carbonate Potassium on anhydrous potassium carbonate result from the following experiments:

In exactly parallel experiments was Ver-turn of catalysts, which consisted of a 3,46gewichtsprozentigen dispersion of sodium or potassium on anhydrous potassium carbonate, at 160 ⁰ C and a pressure of 105 kg / cm ² of propylene The maximum activity of the potassium catalyst only about 80% of that of the sodium catalyst, and its half-life, ie the time in which the catalyst activity has dropped to half of its maximum value, is considerably lower. Also, the percent conversion per pass is lower when the potassium catalyst is used.

Claims (2)

Patent claims: 1. A process for the codimerization of olefinic hydrocarbons with at least 3 carbon atoms in the molecule or mixtures of such olefins with ethylene at elevated temperature and pressure in the presence of an alkali metal catalyst applied to a carrier substance, characterized in that the codimerization is carried out at a temperature of 100 to 200 ⁰ C and a pressure between atmospheric and 280 kg / cm ² , optionally in the presence of hydrogen or a hydrogen-containing gas, in the presence of 1 to 20 percent by weight of sodium metal on an anhydrous potassium, rubidium or cesium compound-containing catalyst carried out by dispersing molten Sodium metal has been produced at a temperature in the range from 250 to 500 ^° C. on a finely divided, anhydrous compound of potassium, rubidium or cesium that is stable at this temperature, preferably in an inert gas atmosphere. 2. The method according to claim 1, characterized in that the codimerization in Presence of a dispersion of 4 to 6 weight percent sodium metal on anhydrous potassium carbonate Performs as a catalyst.