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INVENTION
Patent of the Russian Federation RU2148070
A METHOD FOR OBTAINING ENVIRONMENTALLY CLEAN DIESEL FUEL
The name of the inventor: Somov VE; Zalishchevsky G.D .; Gayle AA; Semenov LV; Varshavsky OM; Koldobskaya LL
The name of the patent holder: Limited Liability Company "Production Association" KIRISHINEFTORGSINTEZ "
Address for correspondence: 187110, Leningrad Region, Kirishi, Sh.Entuziastov, 1, LLC PO KIRISHINEFTEORGSINTEZ
Date of commencement of the patent: 1999.02.15
The invention relates to an oil refining industry and can be used to separate aromatic hydrocarbons from a diesel fraction. The method consists in liquid multi-stage countercurrent extraction of aromatic hydrocarbons and organo-sulfur compounds from the hydrotreated diesel fraction with a heterogeneous mixture of solvents containing acetonitrile or acetonitrile with 2-5 wt% water and pentane, with an acetonitrile to feed ratio of 3-5: 1 by weight, a pentane to Raw materials 0.5-1.5: 1 by weight and process temperature 30-50 ° C. The technical result is the production of environmentally friendly diesel fuel.
DESCRIPTION OF THE INVENTION
The invention relates to an oil refining industry and can be used to separate aromatic hydrocarbons from a diesel fraction in order to produce environmentally friendly diesel fuel.
As a result of the process of hydrotreatment of straight-run diesel fractions, the sulfur content is reduced to 0.05-0.2% by weight, and aromatic hydrocarbons are practically not hydrogenated, their concentration in the hydrotreated diesel fraction remains at 25-35% by weight. At the same time, in accordance with TU 38.1011348-90, amend. 1, the content of aromatic hydrocarbons in diesel-fueled diesel fuel DLESH-B should not exceed 20% by weight [1], while abroad these restrictions are even more stringent - up to 10% by weight, and in Sweden - no more than 5% by weight [2]. Very stringent requirements are imposed abroad for diesel fuels for urban conditions for sulfur content - not more than 0.005% by weight [3].
Various extractants have been proposed for extraction of arenes from middle distillate petroleum fractions, in particular from diesel fractions [4]: furfulol, imidazoline derivatives, N, N-dimethylimidazolidone, b- methoxypropionitrile, etc. The most technically similar and achievable effect to the method according to the invention Separation of aromatic hydrocarbons from kerosene-gas oil fractions by extraction with aliphatic dicarboxylic acid esters - dimethyl malonate and dimethyl succinate [5], which we selected as a prototype.
The main drawback of all the proposed extractants is a high boiling point (dimethylmalonate 181 ° C, dimethyl succinate 195 ° C), the formation of azeotropic mixtures with saturated hydrocarbons of the diesel fraction and, as a consequence, the impossibility of using the simplest method of regenerating extractants-rectification.
In order to increase the selectivity of the extraction process and facilitate the regeneration of the extractant, it is proposed to use a heterogeneous mixture of acetonitrile-water-pentane solvents to separate aromatic hydrocarbons from the hydrotreated diesel fraction. Acetonitrile (bp 81.6 ° C) does not form azeotropic mixtures with components of the diesel fraction and, like pentane, can be removed from the extract and raffinate phases by rectification.
As follows from the results of extraction of methylnaphthalenes (a mixture of a and b isomers) from a mixture with tridecane at a concentration of methylnaphthalene 35 wt. %, Solvent: raw material ratio of 1.5: 1 by weight and temperature of 30 ° C, the proposed extraction system consisting of acetonitrile with 2% by weight water and pentane at a feed to final ratio of 0.5: 1 by weight is more effective than Dimethyl malonate, dimethylsuccinate and furfural (see Table 1).
As a raw material for the production of environmentally friendly diesel fuel, a hydrotreated diesel fraction of 222-375 ° C with a refractive index n D20 of 1.4700, a density r 240 0.8414, a viscosity of 5.87 (20 ° C) and 3.0 (50 ° C) mm 2 / s, containing 27.1% by weight aromatic hydrocarbons and 0.03% by weight sulfur.
The results of a five-step countercurrent extraction of arenes from the hydrotreated diesel fraction of the proposed extraction system are shown in Table. 2. Practically under any process conditions (with the exception of experiment No. 4), a raffinate is obtained that satisfies the DLECH-B fuel requirements in terms of arene content. If it is necessary to produce this fuel as an optimal process condition, it is possible to recommend experimental conditions N 2, in which more than 50% by weight of arenes are recovered at a sufficiently high concentration in the extract. The characteristics of the raffinate and the extract obtained under the conditions of experiment No. 2 are shown in Table. 3. As follows from the data given, along with the arenas, sulfur-organic compounds are well extracted-raffinate in terms of sulfur content meets the requirements for foreign diesel fuels for urban conditions.
When carrying out the extraction process under the conditions of experiments Nos. 1 and 5 (Table 2), the arene content in the raffinate is reduced to less than 10% by weight, corresponding to environmentally friendly foreign diesel fuel. In this case, the experimental conditions N 5 are more preferable because of the more selective extraction of aromatic hydrocarbons - their concentration in the extract is much higher with a higher yield of raffinate.
Example 1
In a sealed container equipped with a magnetic stirrer, 10 g of a feed containing 35 wt. % Methylnaphthalenes and 65% tridecane; 15 g of acetonitrile containing 2% by weight of water and 5 g of pentane. The vessel is incubated with stirring for 20 minutes at 30 ° C. After settling, the two phases are separated, weighed and analyzed chromatographically. The top layer (raffinate phase) contains: 1.18 g of methylnaphthalenes, 6.31 g of tridecane, 0.73 g of acetonitrile and 4.78 g of pentane. The lower layer (extract phase) contains: 2.32 g of methylnaphthalenes, 0.19 g of tridecane, 0.3 g of water, 13.97 g of acetonitrile and 0.22 g of pentane. The concentration of methylnaphthalenes in the extract was 92.4% by weight. The degree of extraction is 66.3%.
Example 2
The hydrotreated diesel fraction (flow rate 100 g / h) and pentane (100 g / h) are fed to the bottom of the packed column with an efficiency of 5 theoretical stages at a temperature of 30 ° C., and acetonitrile in the upper part with 2 wt. % Water (flow rate 300 g / h). As a result of countercurrent extraction, once the stable mode is reached, both the raffinate phase (192.3 g / h) and the extract phase (307.7 g / h) are taken at the same time. The rectification on the column of the efficiency of 20 theoretical plates from 192.3 g of the raffinate phase distills 92.3 g of pentane and 17 g of aqueous acetonitrile (including 16.7 g of acetonitrile and 0.3 g of water). In the bottom residue, 83.0 grams of raffinate containing 14.3% by weight arenes remains. The composition of the raffinate phase, wt. %: Acetonitrile 8.68; Water 0.16; Pentane 48.00; Arenas 6,19; Saturated hydrocarbons of the diesel fraction 36.97.
From 307.7 g of the extract phase, 7.7 g of pentane, 283 g of aqueous acetonitrile (including 277.3 g of acetonitrile and 5.7 g of water) are distilled off on a distillation column. 17.0 g of an extract containing 89.8% by weight of arenes is obtained in the bottom residue. The composition of the extract phase, wt%: acetonitrile 90.12; Water 1.85; Pentane 2.50; Arenas 4,94; Saturated hydrocarbons of the diesel fraction 0.59.
The remaining experiments, the results of which are presented in Table. 2 was carried out according to the procedure described in Example 2.
USED BOOKS
1. Chulkov P. V., Chulkov I.P. Fuels and lubricants. Moscow: Politechnica, 1996. - 304 p.
2. Oil and gas technologies. 1995. - N 2. - P. 52.
3. Erdol - Erdgas - Kohle. - 1998. - Bd. 114, N 4. - S. 176.
4. Krasnogorskaya NN, Gabdikeeva AR, Grushevenko AE, Khlestkin RN Extraction of average petroleum fractions. - Moscow: Chemistry, 1989. - 72 p.
5. Auto. St. 432116 (USSR), MKI C 07 C 7/10, C 07 C 15/00; BI N 22, 1974 (prototype).
CLAIM
A method for producing ecologically clean diesel fuel by liquid multi-stage countercurrent extraction of aromatic hydrocarbons and organosulfur compounds from a hydrotreated diesel fraction, characterized in that an heterogeneous mixture of solvents containing acetonitrile or acetonitrile with 2 to 5% by weight of water and pentane is used as the extractant in the ratio Acetonitrile to feedstock 3 - 5: 1% by weight, pentane to feed ratio 0.5 - 1.5: 1% by weight and process temperature 30 ° -50 ° C.
print version
Date of publication 09.04.2007гг
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