RU1786059C - Process for purifying oil fractions of petroleum - Google Patents

Abstract

For the purification of oil fractions of oil by extraction, N-methylmorpholon-3 is used as a selective solvent. 5 tab.

Description

The invention relates to the oil refining industry and can be used to purify oil fractions of oil from polycyclic aromatic hydrocarbons, resinous substances and heteroatomic compounds that degrade the performance of oils - reduce the viscosity index, thermal and thermo-oxidative stability of lubricating oils; degrade the dielectric properties of transformer oils, etc.

Known methods for cleaning oils from unwanted impurities by liquid extraction using dimethylsulfoxide, dimethylformamide, trimethylphosphate, morpholine, phenol, furfural, N-formylmorpholine, N-acetyloxazolidine, 2,5-dimethyl-1,3 as selective solvents , 4-oxadiazole. However, these methods are not effective enough due to the low extraction properties of the solvents used - low selectivity or low solvent

ability in relation to recoverable components, insufficient thermal stability, high toxicity.

The closest in technical essence to the invention and the most effective of the known methods is the method of purification of distillate oil fractions, which consists in treating the oil fraction with a selective solvent - N-methylpyrrolidone at a temperature above 10 ° C and the ratio of extractant: oil per fraction (0 5-4.5): 1. The viscosity index of the lubricating oil after dewaxing of the raffinate increases by 10 units compared to the starting fraction. The disadvantage of this method is the low yield of purified oil (62% per fraction 420-500 ° C) due to the relatively low selectivity of N-methylpyrrolidone in relation to polycyclic arenas, which leads to the loss of valuable components of the extract oils. Increasing the selectivity of N-methylpyrrolidone by using it in a mixture with water leads to

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a decrease in the quality of the raffinate and an increase in energy costs due to the need to increase the ratio of extractant to raw materials.

The purpose of the invention is to increase the yield and improve the quality of the purified oil.

The goal is achieved by using N-methylmorpholon-3 as an extractant. l

N-Methylmorpholone-Z.

N

..., VCH3j

It is a colorless liquid with a faint characteristic odor, readily soluble in water, i.e., boiling point. 103 ° C at 13 mmHg, density at 20 ° C 1.14 g / cm3, refractive index at 20 ° C 1.4780,

Previously, N-methylmorpholone-3 has been proposed for the isolation of lower aromatic hydrocarbons from mixtures thereof with non-aromatic hydrocarbons.

N-Methylmorpholone-3 belongs to the class of cyclic amides (lactams), unlike N-methylpyrrolidone, it has an additional heteroatrm-oxygen in its structure, which ensures its higher selectivity with respect to aromatic hydrocarbons and heteroatomic compounds of various structures. In industry N-methylmorpholone-3 can be obtained from available raw materials - diethylene glycol and methylamine in two stages according to the scheme

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N-Methylmorpholon-3 exhibits a good combination of extraction and operational properties:

1) the selectivity of N-methylmorpholone-3 with respect to the standard hexane-benzene system, estimated as the ratio of the activity coefficients of hexane and benzene at infinite dilution in a solvent, is 16.5 at 25 ° C, while the selectivity of N- methylpyrrolidone under the same conditions 13.1;

2) N-methylmorpholone-3 shows high thermal and hydrolytic stability, which is a necessary property of a selective solvent. Boiling of N-methylmorpholone-3 at 230 ° C in air for 100 h, both anhydrous and in the presence of 5 % of water, practically not

causes a change in its viscosity, which indicates the absence of a gumming process / Chromatographic analysis shows the absence of low boiling,

and high boiling decomposition products. High hydrolytic and thermal stability allows the solvent to be regenerated from the extract phase by distillation, and from the raffinate

phase washing with water, followed by its distillation.

The extraction properties of N-methylmorpholone-3 were evaluated as on artificial mixtures simulating the composition of oil

fractions of oil, and industrial fractions x ..

Example 1. 6.66 g of a mixture containing 35% by weight of diphenyl sulfide and 65% by weight of tetradecane and 13.32 g of N-methylmorpholone-3 are loaded into a separatory funnel. After stirring for 10 minutes and settling for 20 minutes, two layers are formed which are separated and weighed. The weight of the lower (extract) layer is 15.28 g. Weight

top (raffinate) layer 4.70 g. The extract and raffinate phases are analyzed chromatographically. The composition of the raffinate phase, wt.%: Tetradecane 90.5; diphenyl sulfide 6.4; solvent 3.1. Extract composition

phase, wt.%: tetradecane 2.1; diphenyl sulfide 11.7; solvent 86.7. The recovery of diphenyl sulfide is 76.7%; The yield of raffinate 68.3 wt.% ..

Example 2. In a separatory funnel

8.28 g of a mixture containing 34.4% hexylbenzene and 65.6 wt.% tetradecane and 16.08 g of N-methylmorpholone-3 are charged. After stirring for 10 minutes and settling for 20 minutes, two layers are formed which are separated and weighed. The weight of the extract phase is 17.13 g, the weight of the raffinate phase is 7.22 g. Both phases are analyzed chromatographically. The composition of the raffinate phase, wt.%: Tetradecane 71.0; hexylbenzene 25.1; solvent 3.9. The composition of the extract phase, wt.%: Tetradecane 1.7; hexylbenzene 5.6; solvent 92.7. The hexylbenzene recovery rate is 33.7% by weight. The raffinate yield is 83.9% by weight.

Example 3. 6.78 g of a mixture containing 35.2 wt.% Dimethylnaphthalene and 64.8 wt.% Tetradecane and 13.56 g of solvent (N-methylmorpholone-3) are charged into a separatory funnel. After stirring in

for 10 minutes and settling for 20 minutes, two layers are formed which are separated and weighed. The weight of the extract phase is 15.66 g, the weight of the raffinate phase is 4.68 g. Both phases are analyzed chromatographically, the extract phase, wt.%: Tetradecane

3.0; 1,3-dimethylnaphthalene 11.4; solvent 85.6, The composition of the raffinate phase, (May.%): tetradecane 80.0; 1,3-dimethylnaphthalene 15.0; solvent 5.0. The recovery of 1,3-dimethylnaphthalene is 74.8% of the potential. The yield of raffinate on May 66.7.%.

Example 4. 6.93 g of an oil fraction of 300-400 ° C and 19.03 g of N-methylmorpholone-3 are charged into a separatory funnel. After stirring for 15 minutes and settling for 20 minutes, two layers are formed which are separated and weighed. The weight of the raffinate phase is 5.736 g, the weight of the extract phase is 20.22 g. The solvent from the raffinate phase is washed with water. The weight of the obtained raffinate is 5.39 g. The starting oil and the obtained raffinate are analyzed on a spectrophotometer. The composition of the extract phase and the extract is determined by the mass difference between the components of the initial charge and the raffinate phase. Cheese, (wt.%): Benzene 40.1; naphthalene 4.6; paraffinic 55.3. The composition of the raffinate, wt.%; benzene 28.4; naphthalene 2.6; paraffin 68.1. The composition of the extract, wt.%: Benzene 81.6; naphthalene 11.8; paraffin 6.6. The recovery of benzene hydrocarbons is 44.9 wt.%, Naphthalene 57.5 wt.%. The yield of raffinate is 77.8 wt.%.

Example 5. Three-stage counter-extraction is carried out in a system of separatory funnels. The temperature at the outlet of the raffinate phase is 90 ° C; at the exit of the extract phase is 70 ° C. Ratio solvent; raw materials 2: 1 mass (1.5: 1 vol.). The amount of feed skipped during the experiment is 1 kg. After entering the regimen, the amount of the obtained raffinate phase is 820 g. After washing the raffinate phase from the solvent with water and drying, the amount of raffinate is 730 g. The feed and raffinate are analyzed on a spectrophotometer. Composition of raw materials, wt.%: Benzene 40; naphthalene 4.6; paraffinic 55.3. The composition of the raffinate, (wt.%): Benzene 23; naphthalene 1.7; paraffinic 75.3. Refractive index at 50 ° C 1.4595. Density at 20 ° C 0.835 kg / m3. The yield of raffinate is 73% by weight. The raffinate viscosity index is 142. Under similar conditions, when using N-methylpyrrolidone, the raffinate yield is May 69.7,%, and the viscosity index is 124.5. .

Table T shows the results of a single-stage extraction of aromatic hydrocarbons and heteroatomic compounds from a mixture with N-methylmofolone-3 tetradecane. As follows from the data presented in table 1, N-methylmofolon-3 shows high selectivity to components to be removed from

the oil fraction to bicyclic arenes (1,3-dimethylnaphthalene) and heteroatom compounds m - diphenyl sulfide and quinoline. The degree of extraction of these compounds in one extraction step is 69.7-81.6 May. % At the same time, monocyclic arenas with long alkyl substituents that do not reduce the performance of the oils are poorly absorbed by N-methylmorpholone in the extract. Thus, 66.3% of hexylbenzene remains in the raffinate phase. Thus, N-methylmorpholon-3 shows not only a high group selectivity, but also a rather high selectivity to arenas with a different number of condensed aromatic rings.

The high selectivity of N-methylmorpholone-3 with respect to bicyclic arenes is confirmed by the results of a single-stage extraction purification of a distillate oil fraction of 300-400 ° C containing 4.6 wt.% Naphthalene hydrocarbons. As follows from the data presented in Table 2, with almost the same yield of raffinate, the content of naphthalene hydrocarbons in it is substantial; significantly lower when using N-methylmorpholone-3 (2.5 and 3.5%) as a selective solvent compared to N-methylpyrrolidone (3.6 and 4.3%).

Three-stage purification of a distillate oil fraction of 300-400 ° C (the characteristics of the fraction are given in Table 3) with N-methyl-morpholone-3 allows to obtain a yield of raffinate 3.3 wt.% Higher than when using N-methylpyrrolidone (table .4). The sulfur content in this case decreases from 0.97 to 0.2 wt.%. The viscosity index obtained is 17.5 units higher than the viscosity index of the raffinate obtained by purification of the same fraction with N-methylpyrrolidone.

The results of a three-stage countercurrent extraction of the oil fraction at 300-400 ° C with selective solvents are given in Table 4.

Table 5 shows data comparing the results of purification of distillate oil fractions with N-methylmorpholon-3 and N-acetyloxazolidine (ed. St. USSR No. 732362).

Since the three-stage counter-flow purification using N-acetyloxazazolidine and N-methylmorpholone-3 was carried out on fractions with different boiling points, the efficiency of extractants was compared by a relative decrease in the ratio

v50 C / V1GO c As follows from the data of Table 5, when cleaning the oil fraction with Nacetyloxazolidine, the decrease in the ratio of v50 s / v 10 ° C of the initial fraction and raffinate is 1.04, and for N-methylmorpholone-3 - 1, 12, which indicates the greater effectiveness of N-methylmorpholone-3.

Thus, the use of the invention will increase the yield of the purified oil fraction while improving its quality due to more selective extraction of bi- and polycyclic erenes, as well as N- and S-containing heteroatomic compounds.

Formulas of the invention

A method for purifying oil fractions of oil by extraction with a selective solvent, which is so that in order to improve the quality of the oil, M-methylmorpholon-3 is used as a selective solvent.

The results of single-stage extraction of arenes and heteroatomic compounds from a mixture with tetradecane N-Methylmorpholern-З. The ratio of solvent: raw material (mass) 2: 1, temperature 50 ° C

The results of a single-stage purification fraction 300-400 ° C

Characteristics of the distillate oil fraction 300-400 ° C

Table 1

table 2

Table 3

The results of the purification of oil fractions of oil with polar solvents

Continuation of Table 3

Table 4

Table 5