SU644762A1 - Method of purifying liquid paraffins from aromatic compounds and sulfides - Google Patents

Description

aluminum with n-heptane at a temperature of 55-65 ° C. The process technology is as follows. The proposed complex contains 55-607 o weight. aluminum chloride and 45-40% weight. n-heptane with a ratio of complex to raw materials 2-5: 1. The process is carried out at 55-65 ° C with the number of extraction steps from 3 to 9, depending on the depth of purification. The method of preparing the complex is based on the initial formation of a saturated solution of aluminum chloride in diethyl ether and the subsequent replacement of the latter from the resulting solution with n-heptane. The diethyl ether displaced from the liquid solution is then distilled off from the aluminum chloride solution in n-heptane (from the complex). Aluminum chloride, diethyl ether and n-heptane are used for the preparation of the complex in a weight ratio of 2: 1: 1. The resulting complex is a light brown liquid with 4 = 1.240 and retains its efficiency and stability during repeated extraction. To assess the extracting properties of the complex, the mutual solubility of the components in the n-tridecane-a-methylnaphthalene-complex system is determined, as well as the distribution and separation factors. Used individual hydrocarbons simulate liquid paraffins. The mutual solubility of the components was determined by the method of isothermal titration at 60 ° C. The composition of the two phases resulting from single-stage extraction was determined by the material balance using the plotted graph until the phase equilibrium in the n-tridecane-mixture composition cc-methylnaphthalene. Single-stage extraction is carried out as follows: known quantities of hydrocarbons and the complex are placed in a thermostatted separating funnel. after 10 minutes of intensive displacement, the mixture is settled for 30 minutes, the extract is displaced from the extract solution by n-heptane, which is removed from the extract by distillation. The raffinate and extract compositions are determined according to the graph shown in the drawing. in the tridecane-a-methylnaphthalene-complex system. The resulting solubility curve refers to closed-piece diagrams. It shows that the paraffinic hydrocarbon does not dissolve in the complex at 60 ° C. The separation coefficients of α-methylnaphthalene SDL) and n-trpdecane (KN.) Are defined as the ratio of the concentration of the corresponding hydrocarbon in the Phase extract to its concentration in the raffinate phase. The separation factor p is determined by the formula where K and KN. - the distribution coefficients of the aromatic and non-aromatic hydrocarbon, respectively. From the table. 1, the results of the determination of these indicators show that the distribution coefficient of cc-methylnaphthalene is higher than one, and the separation coefficient is quite high. This indicates the high efficiency of the complex for the extraction of aromatic hydrocarbons. Table 1 an - a-methylnaphthalene - complex 60 ° C)

The raw material used is liquid paraffins obtained by adsorption on zeolites from kerosene-gas oil fraction of Ozexautian oil.

Some indicators of the quality of raw materials are given below.

Refractive index at 20 ° С1.4310

Density at 20 ° С0,7650

Content, wt%:

aromatic hydrocarbons1, 86

"-Paraffin hydrocarbons95, 5

sulfur0.03

Fractional composition, ° С:

NK213

10% 220

20% 226

40% 234

60% 243

80% 254

90% 263

95% 273

KK285 at 99% yield

Example I. A technical fraction of liquid paraffins with a boiling range of 213-285 ° C, obtained by adsorption on zeolites from kerosene-gasoil fractions of North American oil and containing 1.86% by weight. aromatic hydrocarbons and 0.03% of the total sulfur, is subjected to countercurrent extraction purification with a complex containing 60% by weight. aluminum chloride and 40% weight. “-Heptane. The temperature is 60 ° C, the weight ratio of the complex to the raw material is 3: 1, the number of extraction steps is 3.

N-heptane is distilled off from the raffinate solution (no more than 10%) and after contact cleaning with clay, purified paraffins are obtained with a yield of 80%, containing 0.42% by weight. aromatic hydrocarbons and 0.001% sulfur.

The complex is regenerated from the extract solution by stripping with n-heptane, fed in a 1.5: 1 weight ratio at 60 ° C, and the complex is separated from the extract and returned to the extraction. The extract yield is 14.0% by weight, the content of aromatic hydrocarbons is 10.8% by weight, sulfur is 0.21% by weight.

Example 2. Liquid paraffins (see example 1) is subjected to countercurrent extraction purification with a complex containing 55% weight. aluminum chloride and 45.0% weight. n-heptane, at a temperature of 60 ° C, the weight ratio of the complex to the raw material is 5: 1 and the number of extraction steps is 9.

Purified liquid paraffins are obtained from the raffinate solution after distilling off n-heptane and contact cleaning with a yield of 83% by weight, containing 0.01% by weight. aromatic hydrocarbons and 0.0001% weight. sulfur.

From the extract solution, by stripping with n-heptane, supplied in a weight ratio of 1.3: 1, at a temperature of 60 ° C, the complex is separated from the extract and 5 is returned to extraction. The extract yield is 17.0% by weight, the content of aromatic hydrocarbons in it is 19.4% by weight, sulfur is 0.187 ° by weight.

Example 3. Technical fraction

10 liquid paraffins with a boiling range of 245-314 ° C, obtained by the urea denaraffinization of the diesel fraction of one of the Bashkir sulfur oils and containing 1.6% by weight. aromatic hydrocarbons and 0.01% weight. total sulfur is subjected to countercurrent extraction purification with a complex containing 55% by weight. aluminum chloride and 45% weight. n-heptaia. Temperature 60 ° C, the weight ratio of the complex

0 to the raw materials 5.5: 1, the number of extraction steps 10.

By successive distillation of n-heptane and contact cleaning from the raffinate solution, purified paraffins are obtained,

5, the yield of which is 83.5% by weight, containing 0.01% by weight. aromatic hydrocarbons and 0.0001% weight. sulfur.

From the extract solution by re-exposure with n-heptane, supplied in a weight

At a ratio of 1.5: 1, at a temperature of 60 ° C, the complex is separated from the extract and returned to extraction. The extract yield is 16.5% by weight, the content of aromatic hydrocarbons in it is 9.6% by weight, sulfur is 0.06% by weight.

five

The proposed method allows purification of liquid paraffins — raw material for the production of BVK — from aromatic and sulfur compounds. In crude liquid paraffins, aromatic compounds

0 are mono- and polycyclic hydrocarbons. The latter are highly undesirable both in the production and in the use of BVK, since they remain and accumulate in the target

5 final product.

Studies by the spectral method of the composition of aromatic hydrocarbons in paraffies purified by the proposed method to a residual content of 0.01% by weight showed that there are no bicyclic hydrocarbons in the studied samples, and the tricyclic content ranges from 0.00005% to no.

The content of sulfur compounds and raw materials for BVC is also undesirable. In samples of paraffins refined according to the proposed method, sulfur concentration was determined using Rene nickname and was 0.001-0,0001% by weight.

The mode and results of cleaning are given in table. 2

(Raw materials are fractions with a boiling range of 213-285 ° С from ozexautian oil).

Indicators of cleaning liquid paraffin

The results show that the complex based on chlorine aluminum and n-heptane is highly selective and can be used for deep purification of liquid paraffins from aromatic hydrocarbons. Deep paraffin de-aromatization is achieved when the complex-to-raw ratio is 1.5: 1 (instead of 6.5: 1 when cleared with a mixed solvent) and when using a high-performance co-activating device (number of contact stages 9, instead of 14 when cleared with a mixed solvent 2).

Claims (2)

1.Silischev NN and others. Obtaining high purity paraffins by the method of solvent extraction. “Oil Refining and Petrochemicals, 1974, No. 2, p. 41 2. USSR author's certificate number 417463, cl. From 07 to 7/10, publ. 1973 (prototype).