DE767815C - Process for scrubbing olefins from gases - Google Patents

Description

Zierfahren for scrubbing olefins from gases It is known for Washing out of olefins from gases, as they are e.g. B. arise when splitting hydrocarbons, as a washing liquid a solution @ of copper salts, z. B. of cuprous chloride, nitrate, formed or salicylate. One has to increase the solubility of cuprochloride has already been proposed, hydrochloric acid or ammonia, or an Öxyalkylamin to add. In general, washing liquids were used that were about 5 to 10% g of copper in 100 cc.

It has now been found that one can obtain a particularly extensive absorption of olefins from gases when a hydroxyalkylamine-containing aqueous solution is used as the washing liquid of Cupronitrat whose copper content is about 1 to 5 g per 3o ioo cc of solution. This had to be surprising, since solutions of other cupro salts, in particular the cuprochloride mainly used up to now, show no appreciable increase in the absorption capacity for olefins when the copper content is increased by about 15 g per 100 ccm.

The following compilation shows the volume parts of ethylene that are absorbed by a volume part of cuprochloride solution or cupronitrate solution at 20 ° and 76o mm mercury pressure under otherwise identical conditions. Copper content in parts: \ ethylene glioo cc cuprochloride cupronitrate 5 5.4 I 6.6 io 10.7 i 12.8 15 14, i 18.5 20 15.7 24.0 25 16.4 28.9 30 16.7 33.4 From the table it can be seen that with a copper content of the solution of 5 to 10 g per 100 ccm there is no significant difference in the absorption capacity of the chloride and the nitrate, but that at a concentration of about 15 to 30 g per 100 ccm the nitrate absorbs considerably more ethylene than the chloride.

The rate of absorption of cupronitrate solutions also increases with increasing copper concentration to a considerably greater extent than that of cuprous chloride solutions. Thus, under certain conditions, a chloride solution containing oxyalkylamine takes with -2 i g copper in 100 ccm in one minute only about i i parts by volume of ethylene, while a correspondingly composed nitrate solution in the same time absorbed about 19 parts of it under the same conditions.

Another advantage of the cupronitrate solution compared to the cuprous chloride solution is that it is much more stable than the chloride solution from which Precipitates consisting mainly of copper oxide can easily be deposited.

It is advantageous to prepare suitable cupronitrate solutions from copper oxide, which is obtained in a mixture of oxyalkylamine and aqueous nitric acid solves. In order to accelerate the dissolution, it is expedient to use ammonia or ammonium salts to.

Suitable solutions can also be prepared by first Copper oxide dissolves together with ammonium nitrate in aqueous ammonia and this solution then the oxyalkylamine is added. For the extraction of the cupro salt solution one can also start from cuprin nitrate solutions and these with the help of reducing agents that can be easily removed again or when the solution is used later do not disturb, e.g. B. Hy droxylamin or hydrazine, convert into cupro salt solutions. The oxyalkylamine can be added before or after the reduction.

The mixture of cupronitrate, water, oxyalkylamine and optionally ammonia is then heated, if necessary, in order to remove the ammonia and as much water as necessary. that the content of 1, ösuilg of 1-Zupfer is about 15 to 30 100 ccin LVsull <c @ l @ Lel @ t.

The most common oxyalkylamines are the simple amino alcohols, z. v. Jlolloätilalltllamin, or their ether in question. Of these, the copper salt solution added about 2 moles per mole of copper.

The lyes obtained in this way are neither sensitive to the cold nor to the cold. You can therefore on the one hand concentrated by heating to the desired concentration and on the other hand are cooled to low temperature down to about -30 °, without the excretion of salts. They are also not very sensitive to atmospheric oxygen.

The olefins are extracted in the usual way with the help of these alkalis washed out of the gases. This can be done under normal or increased pressure. Due to the high capacity of the liquors for olefins, z. B. for the The individual olefins can also be washed out at a pressure of 2 to 3 atmospheres Wash out separately or enrich in the gases by looking at different pressures washes in several stages. In this way, z. B. Butadiene and Buty len win separately.

The absorbed gases can be recovered from the scrubbing liquid in the usual manner, e.g. B. by heating in a vacuum to 3o to 40 °. EXAMPLE i 3.5 kg of copper oxide and 5 kg of crystallized ammonium nitrate are dissolved with stirring or shaking in 8 1 20% strength ammonia water at 30 ° to 40 ° with the exclusion of air. 6.31 of 96% monoethanolamine is added to the caustic solution obtained (about 1.5 liters) and the mixture is heated to between 10 and 12 °. In addition to all the ammonia, so much water escapes that the solution is reduced to approximately its original volume.

The finished lye has a specific weight of 1.39 at 20 °. she contains about 40 percent by weight ethanolamine and 23 percent by weight water. Your total copper content is 25 g / 100 ccm, of which 90 to 95% are in monovalent form.

i 1 of this lye dissolves i.71 butylene at 20 ° under normal pressure, 5.1 1 propylene, 261 ethylene, 351 butadiene.

Saturated hydrocarbons remain practically undissolved.

Example e i 1 of the liquor prepared according to example i is mixed with further So cc of ethanolamine and 6o g ammonium nitrate added and concentrated so long, until their boiling point has risen to z36 °. A lye is obtained with about 32 g of copper 100 cc each, which at 20 ° and normal pressure absorbs 31 parts by volume of ethylene ".

EXAMPLE 3 A mixture of 10 parts by volume of the ammoniacal cupronitrate solution prepared according to Example 1 with 6.5 parts by volume of monopropanol asnin is concentrated until its boiling point has risen to 12 °. A lye with about 24 g of copper per 100 CCM is obtained.

This liquor absorbs 25.7 parts by volume of ethylene at 20 ° and normal pressure. EXAMPLE 4 10 parts by volume of the ammoniacal cupronitrate liquor prepared according to Example 1 are mixed with g parts by volume of aminodiglycol (CH.NH2-CH2-0 # C, H2 # CH20H) and concentrated until its boiling point has risen to 140 ° a lye with about 24 g copper per 100 ccm, which absorbs 23.2 parts by volume of ethylene. EXAMPLE A mixture of 7 parts by volume of ionoethanolamine, 4 parts by volume of 68% nitric acid, 2 parts by volume of 20% ammonia and 0.5 parts by volume of water is saturated with excess copper oxide at 40 ° by shaking it for two days and then concentrated after separation from the residue until their boiling point has risen to 25 °. A lye with 279 copper per 100 ccm is obtained, which at 20 ° and normal pressure takes up 27.3 parts by volume of ethylene.

Claims (1)

PATENT CLAIM: Process for washing olefins from gases with an aqueous cupronitrate solution containing oxy- = -alkylamines, characterized in that a cupronitrate solution is used which contains about 15 to 30 g of copper in 100 ccm. To distinguish the subject matter of the invention from the state of the art, the following documents have been considered in the grant procedure: British patent specifications No. 424 843, 428 io6.