A method of producing benzene and dibenzocrown high-octane mixture

 

(57) Abstract:

Describes a method of producing benzene and dibenzocrown high-octane mixture of hydrocarbon mixtures containing at least an aromatic and nonaromatic hydrocarbons having six or more carbon atoms, wherein the initial mixture is separated by distillation at CBM product containing not more than 3 wt.%, preferably not more than 1 wt.% benzene, and the distillate containing predominantly hydrocarbons, C6in which not more than 5 wt. %, preferably not more than 0.5 wt.%, toluene and no more than 36,6 wt.%, preferably not more than 10 wt.%, nah7which is subjected to extractive distillation in the presence of a polar organic, aprotic, solvent-related dipole moment to the square root of the molar volume, more preferably more and a boiling point of 150 to 250C, as distillate output stream containing predominantly of nonaromatic hydrocarbons WITH6-C8that may unite with kubovy product of rectification, as well as the cubic product is a mixture of the indicated solvent with hydrocarbons, which then distilled off the thread with the higher boiling points. The technical result - the reduction of energy and capital intensive process. 2 C. p. F.-ly, 2 ill., table 2.

The invention relates to the field of production of benzene and high-octane mixtures.

More specifically the invention relates to the field of production of benzene and dibenzocrown high-octane hydrocarbon compounds from hydrocarbon mixtures containing aromatic and non-aromatic hydrocarbons.

The known method [Reference oil, L., Chemistry, 1986, S. 120-136] high octane hydrocarbon mixtures containing aromatic and non-aromatic hydrocarbons, including benzene and its homologues with hydrocarbon substituents, by catalytic thermal conversion of petroleum fractions, particularly the catalytic reforming process, usually carried out under hydrogen pressure at a temperature amounts to 400-650oC. the Products of thermal conversion (after separation of the light components) are mixtures of aromatic and non-aromatic hydrocarbons, including contain significant amounts of benzene, toluene, xylenes and nah6-C8+.

The known method [Reference oil, L., Chemistry, 1986, c. 257 - tie (possibly combined with rectification) selective polar solvents are mono-, di-, tri - and tetraethyleneglycol, sulfolane etc.

At the same time as the raffinate receive a product containing predominantly non-aromatic hydrocarbons, and the extract is a mixture containing a polar solvent and preferably aromatic hydrocarbons. From this mixture are then distilled off stream containing primarily a mixture of aromatic hydrocarbon and polar solvent return to the zone (apparatus) liquid-liquid extraction.

The mixture of these hydrocarbons are then separated by distillation into streams, respectively, containing mainly benzene, toluene and xylenes.

The disadvantage of this known method is the high energy intensity and capital intensity. This is due to the need to circulate a very large mass of the polar solvent (which implies also its a big loss), and low coefficient of efficiency of mass transfer devices (plates, etc.,) in liquid-liquid extraction (compared to rectification it is usually below 5 to 10 times). The method cannot be effectively used for solving the problem of allocation of benzene from the reaction mixture containing aromatic and non-aromatic, uglevodorov etc.).

At the same time, these tasks become of great commercial importance, because according to internationally accepted standards, are not allowed content of benzene in gasoline blends above 1% (and it should be deleted), while it is advisable to remain part of the gasoline, toluene, xylene and other aromatic compounds, because they have a very high octane numbers (respectively 114 and 120).

The known method [Oil, gas and petrochemicals abroad, 1988, No. 10, S. 105-107] separation of hydrocarbon mixtures C6-C10for aromatic and non-aromatic streams extractive distillation with a polar separating agents, such as N-formylmorpholine. This non-aromatic stream is displayed as a distillate of the column extractive distillation, and aromatic compounds benzene, toluene, xylenes and other displays in the composition of the cubic threads with separating agent and then separated from it by distillation. Then you can branch into multiple distillation columns benzene, toluene, xylenes.

This method can be considered as a prototype in relation to offered by us.

The disadvantage of this method [3] is the need to drive away in the s significantly greater than the boiling point of benzene (TKip.80,1o). For example, most non-aromatic hydrocarbon, C7has a boiling 90-100o(for example, n-heptane 98,4o), hydrocarbons, C8100-125o, hydrocarbons, C9130-150o(for example, n-nonan 150,8oand so on, So the method requires significant conversion of relative leucuta shared substances and, as a consequence, the circulation of very large quantities of separating agent and a large reflux numbers, i.e., is very energy and capital intensive.

We propose a method of producing benzene and dibenzocrown high-octane mixture of hydrocarbon mixtures containing at least an aromatic and nonaromatic hydrocarbons having six or more carbon atoms, namely, that the original mixture is separated by distillation at CBM product containing not more than 3 wt.%, preferably not more than 1 wt.% benzene, and the distillate containing predominantly hydrocarbons, C6in which not more than 5 wt. %, preferably not more than 0.5 wt.%, toluene and no more than 36,6 wt.%, preferably not more than 10 wt.%, nah7which is subjected to extractive distillation in the presence of a polar organic, APR is predpochtitelno more and a boiling point of 150 250oC, as distillate output stream containing predominantly nonaromatic hydrocarbon, C6-C8that may unite with kubovy product of rectification, as well as the cubic product is a mixture of the indicated solvent with the hydrocarbon from which further distilled stream containing mainly benzene, which can be further subjected to further distillation of hydrocarbons with higher boiling points.

As one of the variants of the proposed method lies in the fact that, as a polar aprotic organic solvent used substances selected from N-methylpyrrolidone, N,N - dimethylacetamide, N,N-dimethylformamide, Ala(C1-C2)oxopropanenitrile, N-formylmorpholine, including their mixtures with water.

As a variant of the proposed method lies in the fact that a stream containing predominantly nonaromatic hydrocarbon, C6-C7and you can stream containing mainly benzene, put the washing in the vapor or liquid phase with water, then the solvent is distilled at least most of the water and it is sent to the extractive distillation zone.

The term "dibenzopyrene" in f and, but as exhausting mostly benzene, so that the remaining high-octane mixture of a number of benzene does not exceed permissible limits (usually less than 1%).

As a polar aprotic organic solvent, it is preferable to use substances that do not form azeotropes with non-aromatic hydrocarbon, C6. In the case of partial ablation of solvents in the composition of the distillate they can be recovered in any suitable way, for example by extraction with water followed by distillation of the water.

It is possible to use mixtures specified in the claims solvents and their mixtures with other polar substances such as ketones, alcohols, monoalkyl-N-substituted inorganic salts, etc., in particular to reduce the boiling point. The composition of the solvent may include corrosion inhibitors.

Extractive distillation (as usual rectification) can be carried out in a single column unit, or in two or more column apparatus connected functionally by the countercurrent flow of liquid and vapor as one distillation (extractive distillation) column. In the latter case, and hereinafter, the term "above" means "gave the use of the method is illustrated by the following drawings and examples. See the drawings and the examples do not exhaust all of the options for implementing the method, and any other technological solutions, while respecting the essence of the invention set forth in the claims.

According Fig. 1 hydrocarbon mixture F served in a distillation zone (column) 1. From the bottom of the column 1 output stream dibenzopyrans" high-octane mixture (VOS) W1and above after condensation and return phlegmy stream of distillate D1containing mainly hydrocarbons, C6.

Stream D1refer to the zone (column) extractive distillation 2. Above ("next" in the direction of steam flow) it serves stream P, containing mostly solvent. The top (after condensation and return phlegmy) display the flow of distillate D2containing predominantly nonaromatic hydrocarbon, C6-C7. Bottom output stream W2containing mainly solvent and benzene.

Flow W2served in a distillation (desorption) zone (column) 3, above which the output stream D3containing mainly benzene. Bottom output stream W3containing mainly solvent, which is sent to Samorodov with higher boiling points (Fig. not shown).

Flows W1and D2can be connected with the General flow of high-octane mixture.

The circuit shown in Fig. 2, differs from Fig. 1 in that the steam flow from the top of the column 2 (zone 2A) is subjected to contact with water, after which water is evaporated from the solvent in the node 4, and preferably return to the top of zone 2A, and the solvent is sent along with the main stream P in the area of extractive distillation.

Examples illustrating the use of the invention, are given in table. 1 and 2. In examples 1-3 (table. 1) as the polar aprotic solvent used in example 1 - N,N-dimethylacetamide (dipole moment = 3,80 Debye, molecular mass M = 87 g/mol, molar volume at 25oC V = 92,8 cm3/gmol, the parameter TKip.(norm.) = 165,5oC; example 2-N-organic ( = 4,08 dB, M = 99 g/mol, V = 95,6, parameter ) TKip.= 202oC; example 3 - N,N-dimethylformamide ( = 3,82 dB, M = 73 g/mol, V = 77,3, ) TKip.= 157,5oC.

In examples 4-5 (PL. 2) as the polar aprotic solvent used is N-formylmorpholine ( = 4,1, M = 115, V = 99,8, TKip.= 217oC), - methoxypropionitrile ( = 4,0, M = 85,1, V = 90,7 TKip.= 165,5oC), - ethoxypropionate mixture of hydrocarbon mixtures, containing at least an aromatic and nonaromatic hydrocarbons having six or more carbon atoms, wherein the initial mixture is separated by distillation at CBM product containing not more than 3 wt.%, preferably not more than 1 wt.%, benzene, and the distillate containing predominantly hydrocarbons, C6in which not more than 5 wt.%, preferably not more than 0.5 wt.%, toluene and no more than 36,6 wt.%, preferably not more than 10 wt.%, nah C7which is subjected to extractive distillation in the presence of a polar organic, aprotic, solvent having a ratio of the dipole moment to the square root of the molar volume, more preferably more and a boiling point of 150 - 250oC, as distillate output stream containing predominantly nonaromatic hydrocarbon, C6-C8that may unite with kubovy product of rectification, as well as the cubic product is a mixture of the indicated solvent with the hydrocarbon from which further distilled stream containing mainly benzene, which can be further subjected to further distillation of hydrocarbons with higher boiling points.

2.substances selected from N-methylpyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, Ala(C1-C2)oxopropanenitrile, N-formylmorpholine, including their mixtures with water.

3. The method according to PP.1 and 2, characterized in that a stream containing predominantly nonaromatic hydrocarbon, C6-C7and you can stream containing mainly benzene, put the washing in the vapor or liquid phase with water, then the solvent is distilled at least most of the water and it is sent to the extractive distillation zone.

 

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