DE2521702C3 - Process for the separation of acetylene compounds from other hydrocarbons - Google Patents

Description

The invention relates to a process for the separation of acetylene compounds from saturated ones Hydrocarbons or those with olefin or diene bonds or mixtures thereof, preferably can be used for the following purposes: -5

1) For separating propyne, 1-butyne, vinyl acetylene, Diacetylene or acetylene of butadiene, which is saturated alone or in admixture with others and / or olefinic hydrocarbons having the same number of carbon atoms;

2) for the separation of propyne from propylene, which alone or in a mixture with other saturated ones and / or olefinic hydrocarbons having the same number of carbon atoms;

3) for the separation of acetylene from ethylene, which is present alone or in a mixture with ethane.

It is known that the saturated and olefinically unsaturated hydrocarbons, in particular hydrocarbons with diene bond, so far for most applications of Acetylenver- - bonds \ ° must be free, that for example in the Butadienmonomtr the content of compounds with acetylene bond in view of their The poisoning effect on the polymerization catalysts does not exceed 50 parts per million.

Various methods have already been proposed for separating off the troublesome acetylene compounds, some of which are also in use, including selective hydrogenation, fractional distillation or Extractive distillation in the presence of suitable solvents.

These processes allow, if necessary in combination, the separation of acetylene compounds, however, require cumbersome work processes and usually expensive special equipment.

This also applies to the process known from GB-PS 1180 239, in which acetylenes are separated from saturated hydrocarbons by bringing the hydrocarbon mixture into contact ^{with a moist, acidic ion exchange resin containing mercury ions 6 ^} Aldehydes or ketones are hydrated, which can be washed out with water or alkali or which remain when the unchanged proportions of the mixture are distilled off.

However, the degrees of purity achieved with this process were not always satisfactory (residual content of Acetylenes 24-180 ppm).

In contrast to the known methods, the method according to the invention is based on Etherification of the acetylene compounds with an alcohol or a glycol under the influence of acidic ion exchangers, which, surprisingly, also without the presence of an alkali or alkali metal alcoholate takes place as a catalyst.

The process according to the invention for separating acetylene compounds from saturated hydrocarbons or those with olefin or diene bonds or mixtures thereof is characterized by that the acetylene compounds mixed with the other hydrocarbons are present in the presence an acidic ion exchange resin containing mercury ions with an alcohol or a Glycol etherified and the resulting ether distilled off.

The course of the etherification without the assistance of a catalyst is surprising insofar as the presence a catalytically active alkali or alkali alcoholate has so far been an indispensable precondition for the formation of ethers from acetylene compounds and alcohol or glycol (see?. B. »Acetylenes Processes and Products "by M. S i 11 i g, Noyes Dev. Corp., London [1968], pp. 127-128).

According to the invention, the acetylene compounds are etherified in particular with methanol or a glycol, preferably monoethylene glycol or diethylene glycol, being carried out in the presence of an acidic ion exchange resin, containing mercury ions works. The ethers formed are then through one simple and economical rectification process removed.

As already noted, the ion exchange resin used has an acidic character and preferably contains sulfonic acid groups (-SO ₃ H on resins such as polystyrene, divinylbenzene or phenolic resins), but resins which contain -COOH groups can also be used.

The mercury ions can be added to the resin in the form of mercury salts, in particular of mercury nitrate or acetate; the Hg ⁺ + - ion content of the resin can also be lower than its total cationic capacity.

The hydrocarbons that can be purified using the method of the invention are paraffinic and olefinic hydrocarbons and conjugated dienes (especially butadiene, propylene and ethylene).

The etherification can be carried out within a wide temperature range, but is advantageously carried out in a range of -20 to +80 ⁰ C and, with particular advantage at +20 to +60 ⁰ C, preferably being a conventional column with ion exchange resin used; the working pressure is advantageously chosen such that the hydrocarbon stream is kept in the liquid phase at the reaction temperature. The contact time is 2 to 30 minutes.

It is expedient to work in the presence of a stoichiometric excess of alcohol or Glycol compared to the products with acetylene bond; in practice it is appropriate at a molar ratio from Aikohn'i to the whole. Acetylene compounds to work from 1.05 to 2.0.

In addition, it was found that the compounds with acetylene bond in the presence of ion exchange shear resin with mercury ions with any

bonds of the type R-OH (where R is an alkyl, acyl, aryl or cycloalkyl group) in a quantitative manner react with the formation of addition products, which the latter can then simply be distilled off, similar to what has already been exercised for the ethers. s The reactions described above are in particular "vinylation" or etherification reactions showed that all the reactions mentioned without a difference in the gaseous or in the liquid phase can be carried out.

The method according to the invention is based on the examples which do not apply in a restrictive sense explained in more detail.

Example 1 ₍ .

100 g of a resin of the Amberlist 15 type containing groups of the SO3H type were added to 400 cm 'of an aqueous solution of 3% by weight Hg (NO ₃ ^ -H _{2 O).}

The mixture was stirred for one hour, then filtered off under vacuum and the resin under several times Washed vacuum with methanol.

A portion of the resin treated as above was placed in a reaction vessel with a ^{capacity of 20 cm 3,} which was kept at 40 ° C. in the thermostat. A stream of 100 cmVh of butadiene was then continuously pumped into the reaction vessel at a pressure of 5.0 at 1.7: 1.

The content of both acetylenic compounds determined in liquid samples from the reactor was <10 ppm (weight).

Example 2 ^{> 5}

In the reactor described in Example 1, operated at 30 ⁰ C and at a pressure of 4, 200 continuously cmVh butadiene were pumped containing 1.2 wt .-% propyne, 150 ppm of vinylacetylene, 200 ppm 2-butyne and as much methanol that the molar ratio of alcohol to unsaturated compounds was!, 25: 1.

The content of the three acetylenic compounds, determined in liquid samples. the reactor as above <10 ppm (wt.).

Example 3

In the reactor used in Example 1, which was operated at at 3O ⁰ C and a pressure of 10 such propylene were continuously pumped lOOcmVh containing 0.5 wt .-% containing propyne and methanol so much that the molar ratio of alcohol to acetylene compound was 1.15: 1.

The propyne content in liquid samples from the reactor was < 10 ppm (wt.).

Example 4 (Addition of carboxylic acids to acetylene compounds)

The reactor according to Example 1 was used, which was operated at 50 ^° C. and a pressure of 30 atm and was filled with the resin used in Example 1, which had been washed with glacial acetic acid at the end. 50 cmVh of propylene, which contained 0.5% by weight of propyne and sufficient acetic acid for the molar ratio of acetic acid to acetylene compound to be 2: 1, were continuously pumped into the reactor.

The propyne content in the liquid samples from the reactor was < 10 ppm (wt.).

Example 5

According to the reaction scheme shown in the drawing, a reactor 9 with a capacity of 150 cm 'was used used, which was housed in a thermostat and connected to the following lines:

a) Line 1 for introducing the hydrocarbon stream rich in acetylene compounds in the gas phase from underneath;

b) line 2 for drawing off the hydrocarbon stream after the treatment from above;

c) Line 3 for the supply of a liquid stream, which consists of either alcohol alone or from one Mixture of alcohol and ethers can exist from above;

d) Line 4 with siphon for drawing off a liquid sitrate consisting of alcohol and ethers, which is fed into the vessel 8.

The latter stream was in whole or in part via the pump 7 and line 3 into the reaction vessel returned, with a possibly lost part 5 replaced via line 6 with fresh alcohol would.

The reactor 9 was charged with 50 g of the resin prepared according to Example 1, which was then moistened well with methanol (drawn off via line 4). ^{The reactor was kept at 50 °} C. with the aid of a liquid circulating via lines 10 and II, the pressure being 1 atm. A propylene stream of 1.2 g / h containing 0.1% propyne was then passed in via line 1, while about 50 g / h of the liquid stream withdrawn from below via line 4 was completely returned to the reactor from above via line 3 .

The propyne content in the gaseous samples from the reactor was also in this case <10 ppm (weight).

1 sheet of drawings

Claims (2)

Patent claims: 1. Process for the separation of acetylene compounds from saturated hydrocarbons or those with olefin or diene bonds or mixtures thereof, characterized in that that the acetylenic compounds mixed with the other hydrocarbons are present in the presence an acidic ion exchange resin containing mercury ions with an alcohol or etherified with a glycol and the resulting ether is distilled off. 2. The method according to claim 1, characterized in that one is an acidic ion exchange resin? used with silicone acid groups.