SU1161537A1 - Method of purifying paraffins - Google Patents

Abstract

1. A method for purifying paraffins by treating them with dimethylformamide, characterized in that, in order to maintain the degree of purification and reduce the consumption of solvent, the treatment is carried out in the presence of low molecular weight aromatic hydrocarbons. 2. A method according to claim 1, characterized in that the low molecular weight hydrocarbons are mixed with paraffins in a mass ratio

Description

ate

with

h | one . The invention relates to refining and petrochemicals and can be used in oil refineries and petrochemical plants. In modern methods, liquid paraffins, isolated from kerosene-gas-oil fractions of oil, used to obtain protein-vitamin concentrates, and solid paraffins are purified from aromatic hydrocarbon residues by concentrated sulfuric acid or oleum, silica gel and molecular sieves, by hydrogenation 1. The first of these methods has the disadvantage that it forms a lot of difficult-to-use waste - acid tar and consumes irreversibly sulfuric acid and hydrocarbons. The second and third of the prescribed methods do not allow to completely remove aromatic hydrocarbons from n-paraffins, and the presence of Even 0.2% of aromatic hydrocarbons; In purified paraffin, it worsens its quality as a raw material for obtaining protein-vitamin concentrates and medical preparations and as food paraffins. To obtain highly pure paraffins containing aromatic hydrocarbons less than 0 .. 1 wt.%, The extraction of aromatic hydrocarbons with selective solvents is used 2 J. A method of cleaning paraffin by treating them with dimethylformamide in C3 is known. However, according to this method, the purification of solid and liquid paraffins containing up to 5% of oil and small cyclic high molecular weight aromatic hydrocarbons is difficult. Only using a 10-fold amount of pure dimethylformamide is it possible to purify liquid paraffins to an aromatic hydrocarbon content of .0.1%. The purpose of the invention is to increase the degree of purification of paraffins and reduce solvent consumption. This goal is achieved by the fact that according to the method of cleaning paraffins by treating them with dimethylformamide, the treatment is carried out in the presence of low molecular weight aromatic hydrocarbons. 72 Processing is carried out at 30-80 ° C. In addition, low molecular weight aromatic hydrocarbons are mixed with paraffins before entering the extractor or in the extractor itself in a mass ratio of (0.25-2): 1. A distinctive feature of the method is that by artificially increasing the concentration of aromatic hydrocarbons in the feedstock with an additive low molecular weight denyc aromatic hydrocarbons are facilitated by the subsequent extraction of high molecular weight aromatic hydrocarbons and oils from paraffins. Purification of paraffins is carried out by extraction with dimethylmethyl (DMF. With ZO-ZO C, supplied in an amount of up to 400 wt.% For raw materials, in one or more stages of contact. The resulting raffinate and extract solutions are separated by sequential distillation of the aromatic hydrocarbon and solvent. Example 1 Liquid paraffins (obtained from dewaxing diesel fuels, boiling away within 180-350 ° C, containing 4.2% of aromatic hydrocarbons) are diluted with benzene in an amount of 100% by weight of raw materials and purified by dimethyl forms The amount of DMF is 300 wt.% for liquid paraffins. Extraction is carried out in temperature-controlled separating funnels at 30 ° C pseudo-countercurrent in five contact stages. Thus, an extract solution of 417 wt.%, a raffinate solution of 83 May. raw materials. After phase separation and distillation, they are obtained in a raw material, wt-1%: from a raffinate solution: purified liquid paraffins with an aromatic hydrocarbon content of 0.04%, 80%, benzene, 1.0j DMF2; from the extract solution: extract 20%, benzene 99%, DMF 298. The results of this and other examples are given in table. 1. From table. 1 that under these conditions deeply purified liquid paraffins are obtained. Example 2. Raw paraffin (I) of commercial grade T (technical) paraffin with an oil content of 3.8 wt.% And a melting point of 51 ° C is subjected to purification with dimethylformamide (DMF) with dilution3

We supply raw material with benzene in the form of 100 wt.% for raw materials. The amount of DMF is 400% paraffin. Extraction is carried out in temperature-controlled separating funnels at 60 ° C with a pseudo countercurrent in 5 contact stages. An extract solution is obtained.

480.9 wt.%, Raffinate solution

119.10 wt.% For raw materials.

After separation of the phases by distillation, the following was obtained in wt.% For raw materials: from a raffinate solution: purified food paraffin From 84.3, benzene 21.92, DMF 12.88; from the extract solution: an extract of heavy aromatic hydrocarbon 15.7, benzene 78.07, DMF 387, .13.

Example 3. Paraffin raw paraffin brand P (edible) with an oil content of 2.5%, color 210 mm, melting point - 52 ° C, containing benz-VS. pyrene, subjected to purification by extraction with dimethylformamide (DMF) with the addition of toluene in the amount of 100 wt.% on paraffin. The amount of DOPA is 400% for raw paraffin. The extraction was carried out at 60 ° C in four countercurrent contact stages in thermostatted separating funnels.

15374

. After separation of the ph by p-race, the following materials are obtained in wt%: from the raffinate solution: food grade paraffin P-1 85.2, 5 toluene 19.93, DMF 3.88; from the extract solution: heavy extract 14.8, toluene 80.1, DMF 396.09.

After additional purification of paraffins (1-P) at 60 ° С with bleaching earth in the amount of 3% (for paraffin), samples of purified paraffins are analyzed by parameters for food paraffins, GOST-23683-79.

In tab. 2 shows the quality of purified solid paraffins.

The use of the paraffin purification method provides a higher degree of purification of n-paraffins compared to existing methods, which is very important when used as a raw material for the production of protein-vitamin concentrates, lower extractant consumption, thereby increasing the plant capacity, the absence of non-recyclable waste, reducing the requirements for raw materials, depending on the needs of production, makes it possible to increase the production of highly purified paraffins from low-quality raw materials (for example, paraffin m RCT Hj of tehnicheskgo paraffin).

Table 1

At 30 ° C

15

100 100 300

- With

four

100 100 200

4,100,100,100

417

0.04

83

21

311.5 88.5 0.15 35 201 99 0.27 36

With

100 200 100 100 25 100

At 30 ° C 100 200 400

At 60 ° C

four

100 100 300

5 100 - 300 100 - 1000

five

Continued table. one

36 33

242

3.2 114 2.8

76

0.0210.2

81

0.1. 9.8 1,417 93,5 76,2

0,147,5

table 2

Claims (3)

1. METHOD FOR CLEANING PARAFFINS by treating them with dimethylformamide, characterized in that, in order to increase the degree of purification and reduce solvent consumption, the treatment is carried out in the presence of low molecular weight aromatic hydrocarbons. 2. The method of pop. 1, characterized in that · low molecular weight hydrocarbons are mixed with paraffins in a mass ratio (0.25-2): 1. 3. The method according to PP. 1 and 2, characterized in that the treatment is carried out at 30-80 ° C. Od m