DE1273514B - Process for the separation and recovery of aromatic hydrocarbons from mixtures with paraffinic and naphthenic hydrocarbons - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

German class:

Number:
File number:
Registration date:
Display day:

C07c

BOId

12 ο -1/04

12C-1

P 12 73 514.7-42 (F 31571)

July 2nd, 1960

July 25, 1968

It is known to use mixtures of aromatics, paraffins and naphthenes, such as those used particularly in the petrochemical industry occur to separate by selective extractants and this process simultaneously with a Connect distillation. It is also known from fractions of the hydrocarbon mixtures mentioned to separate off the aromatic components by extractive distillation with strongly polar solvents. Furthermore, aromatic hydrocarbons can be separated from non-aromatic hydrocarbons often by azeotropic distillation or by crystallization with adduct formation * See above one can, for example, paraffins from the abovementioned mixtures in the form of their urea adducts isolate and in this way separate from the aromatic hydrocarbons. All these However, measures require a significant amount of energy, since the paraffins or naphthenes have some solubility in the solvents used and extensive fractionation make necessary. When working up fractions with wider boiling intervals is intended, as a rule, a fraction with a narrow boiling interval suitable for the separation operation must first be found which is cumbersome and time consuming.

According to the procedure of the German Auslegeschrift 1102 742 solid Werner complex compounds are a metal salt with an organic nitrogen base for separating mixtures of organic Connections used. The separation takes place via the formation of a cage inclusion connection, taking only aromatic compounds of a certain molecular shape from the original Can be separated mixture.

From the Journal of the Chemical Society, 1956, pp. 1855 to 1858, it is known to use aromatics various silver salts, such as silver fluoroborate, among To solve complex formation. The complex compounds are always produced by dissolving the silver salt in anhydrous aromatic hydrocarbons; it is explicitly pointed out pointed out that the complex compounds are decomposed by moisture.

The invention now provides a process for separating and recovering aromatic hydrocarbons from mixtures with paraffinic naphthenic hydrocarbons by treating the mixture with salts of a metal of an atomic number greater than 12, which is characterized in that the mixture is in a manner known per se with the aqueous solution of a process for separating and recovering aromatic hydrocarbons from mixtures with paraffinic and naphthenic
Hydrocarbons

· ■■ · Applicant:

Farbwerke Hoechst Aktiengesellschaft
formerly Master Lucius & Brüning,
6000 Frankfurt

Named as inventor:

Dr. Ludwig Schläfer, 6239 Fischbach;

Dr. Ulrich Schwenk, 8263 Burghausen;
_ao Dr. Therese Quadflieg, 6233 Kelkheim

Easily soluble silver salt washes the aromatics out of the silver salt solution by freezing it out, shaking it out separated with solvents, heating and / or pressure reduction and the recovered Silver salt solution fed back to the separation stage.

The silver salt solution selectively enriches the aromatic hydrocarbons, but does not take any significant amounts of the paraffinic and naphthenic hydrocarbons, so that a selective Separation into aromatics and non-aromatics takes place, which can be designed quantitatively.

To achieve the greatest possible separation of the mixtures into aromatic hydrocarbons on the one hand and to achieve paraffinic and / or naphthenic hydrocarbons on the other hand, leads when carrying out the process on an industrial scale, the washing is advantageously carried out in countercurrent. For this purpose, it is expedient to use a column which, in order to ensure intensive mixing of the one another To achieve guided phases, equipped with random packings or designed as a vibrating column. A number of centrifugal mixers connected in series can also be used. The silver salt solution is circulated.

The isolation of the aromatic hydrocarbons from the aqueous silver salt solution, which is free from paraffinic and naphthenic hydrocarbons is made by freezing out, shaking out with

809 587/574

Solvents, simple heating and / or treatment under reduced pressure. Has Heating under reduced pressure has proven particularly advantageous. When it comes to thermal Treatment of the silver solution to separate the aromatics results in silver deposits, the silver can easily be put back into solution using the method of German patent 1120439 by adding oxidation to the silver solution

example 1

100 g of a mixture of 50 percent by weight cyclohexane and 50 percent by weight benzene will be introduced hourly at room temperature at the foot of a column filled with Raschig rings, through which Every hour 11 silver fluoroborate solution with 600 g of silver per liter are applied from above. At the head of the Column passes over benzene-free cyclohexane. the

medium, preferably hydrogen peroxide, added. io silver solution that leaves the base of the column A Ge expelled from the silver salt solution at 100 ° C and 200 Torr by distillation of Benmisch Zol is freed of aromatic hydrocarbons and then put again at the top of the column according to known methods, e.g. B. by distillation, broken down into its individual components.

The temperature at which the separation of the 15
Mixing is carried out according to the method of the invention can vary within wide limits. One
the natural lower limit is given by the freezing point of the aqueous salt solution. In general carried out at temperatures below 20 from 50 to 150 ⁰ G contains ⁰ C and preferably in the range between manner is treated as in Example 1 in the same 15O. A mixture of 0 and 50 ° C. is obtained.

The concentration of the silver salt solution should contain as much as possible.

give. Pure benzene is obtained.
Example 2

100 g of an olefin-free mixture obtained in the pressure refining of cracked gasoline, which contains 40% aromatic and 60% naphthenic and paraffinic hydrocarbons with a boiling range

let be high. It generally contains at least 100 g and preferably 500 to 1200 g of silver per liter of solution.

Suitable silver salts with good solubility in water are in particular silver nitrate, silver fluoride, silver fluorosih'cat, Silver perchlorate, silver trifluoroacetate. Aqueous solutions are particularly advantageously used of silver fluoroborate. Mixtures of silver salts can also be used.

As aromatic hydrocarbons which are separated and obtained by the process of the invention let be mentioned in particular: benzene, singly or multiply alkylated benzenes, such as Toluene, ethylbenzene, hexylbenzene, the xylenes, mesitylene and its control isomers, tetrahydronaphthalene, Naphthalene and alkylated naphthalenes.

Representatives of polycondensed aromatic ring systems, for example Änthracene, can also be used separate from solutions in saturated hydrocarbons by the present process.

The method of the invention is particularly suitable for extracting from the various petroleum refining processes resulting mixtures with a wide boiling range, consisting of aromatic, naphthenic and paraffinic hydrocarbons consist of aromatics without prior pre-fractionation to separate the non-aromatics. The process can also be advantageous for separating off benzene or its derivatives from gases or for the separation of azeotropes containing these compounds Mixtures are used.

Claims (2)

Patent claims: 1. Process for separating and recovering aromatic hydrocarbons from mixtures with paraffinic and naphthenic hydrocarbons by handling the mixture with salts of a metal with an atomic number greater than 12, characterized in that that the mixture is washed in a manner known per se with the aqueous solution of a readily soluble silver salt from the silver salt solution the aromatics by freezing out, shaking out with solvents, heating and / or or pressure reduction separates and the recovered silver salt solution of the separation stage feeds again. 2. The method according to claim 1, characterized in that the method with a aqueous silver fluoroborate solution carried out as a silver salt solution. Considered publications: German Auslegeschriften No. 1027 658, 1102742;
U.S. Patent Nos. 1875,924, 2,077,041,891;
Journal of the Chemical Society, 1956, 1855 until 1858. Older patents considered: German Patent No. 1120439. 809 587/574 7.68 ® Bundesdruckerei Berlin