RU2131865C1 - Method of preparing alkyl-tert-alkyl ethers or mixtures thereof - Google Patents

Abstract

FIELD: production of high-octane components. SUBSTANCE: alkyl-tert-alkyl ethers or mixtures thereof with hydrocarbons and/or alcohols are prepared by contacting hydrocarbon mixtures containing at least tert- alkenes and nontertiary alcohol(s) in the presence of acid catalyst followed by separation of at least part of unreacted hydrocarbons from reaction products. At least part of stream taken from top and/or tope portion of rectification zone and containing preferably unreacted hydrocarbons is subjected to liquid-phase contacting with catalyst in additional reaction zone with alcohol(s) optionally admitted therein. Temperature at said zone outlet is maintained by 10 C lower than that at first reaction zone outlet, and the resulting reaction mixture is admitted into said reaction zone. EFFECT: higher conversion of tert-alkene and higher reaction rate in second reaction zone. 3 cl, 2 dwg, 6 ex, 2 tbl

Description

 The invention relates to the field of production of high octane components. In particular, the invention relates to the field of production of alkyl tert-alkyl esters or mixtures containing alkyl tert-alkyl esters.

Known methods for producing alkyl-tert-alkyl esters by contacting hydrocarbon mixtures containing tertiary alkenes and alcohols with acidic catalysts, for example sulfocathionites in once-through (SU 1367854 A3, 01/15/08) [1] or reactive distillation apparatus (RU 1037632 C, 03/10/95)
The disadvantage of the method [1] is the use of a large molar excess of alcohol with respect to tert-alkene and the need for complex subsequent recovery of alcohol from the target product.

 The disadvantage of this method [2] is the relative complexity of the necessary reactive distillation apparatus and the inability to use active fine-grained catalysts in the form of a nozzle.

Closest to our proposed method is the patent (RU 2032657 C1, 04/10/95) according to which the isobutylene-containing C ₄ fraction and methanol are contacted in the liquid phase in the presence of macroporous sulfocationionite in the U form in two reaction zones, followed by separation of the reaction mixture and the selection of the target product, and the contacting is carried out at a molar ratio of methanol: isobutylene of 0.90 - 0.99: 1 and maintaining the degree of conversion of isobutylene in the first reaction zone of 80-90% and the temperature in the second reaction second zone 20 - 40 ^o C.

The disadvantage of this method is the relatively low conversion of tert-alkene (isobutylene) and an extremely low reaction rate in the second reaction zone at the stated temperature of 20-40 ^o C. In particular, it is difficult to use the method in the processing of hydrocarbon mixtures with a high content of tertiary alkene (in particular, isobutylene) , for example fractions of isoalkanes dehydrogenation and gasoline pyrolysis (after separation of dienes), in which the concentration of isobutylene reaches 40-60%.

We propose a method for producing alkyl tert-alkyl esters or mixtures thereof with hydrocarbons and / or alcohols by contacting mixtures of hydrocarbons containing at least tert-alkenes and non-tertiary alcohol (s) in the presence of acidic catalysts, followed by separation of at least a portion unreacted hydrocarbons from the reaction products by distillation, according to which at least a portion of the stream taken from above and / or from the upper part of the distillation zone and containing predominantly unreacted carbohydrates ode is subjected to liquid phase contacted with the catalyst in the additional reaction zone, possibly with the introduction into it of alcohol (s), the output of which is maintained at a temperature of at least 10 ^o C lower than the outlet of the first reaction zone, and the resulting reaction mixture was fed to the specified distillation zone below the output of the selected stream.

A variant is also proposed according to which contacting with the catalyst (s) prior to rectification is carried out in two or more reaction zones, and at least at the outlet of the latter, the temperature is maintained at least 10 ^° C lower than at the outlet of the first reaction zone.

A variant is proposed according to which, when using two or more reaction zones preceding the rectification, at the outlet of the additional reaction zone, the temperature is maintained at least 10 ^° C higher than in the previous reaction zone and a mixture containing at least dimers of tert-alkenes.

 The term "below the outlet of the sample stream" in the claims is understood as the position remote from the output in the direction opposite to the movement of the vapor stream.

 The direction of flows in the reaction zones can be either from bottom to top, or from top to bottom.

 The selection of the stream from the column 2 to the reactor 3 can be carried out both in the liquid state and in the vapor state with intermediate condensation.

 Using the proposed method is illustrated in FIG. 1 and 2 and examples (see table). These figures and examples do not exhaust all possible embodiments of the method and other options are possible provided that the essence set forth in the claims is observed.

 According to FIG. 1, the hydrocarbon mixture F and the stream of alcohol (s) "C" enters the reactor 1, from which the reaction mixture enters the distillation column 2. At the top of the column 2 and / or from its upper part, stream D 'and / or stream D' 'is discharged, at least a portion of which (s) enters reactor 3 into which a stream of alcohol (s) C 'can be supplied. The reaction mixture from reactor 3 enters column 2 below the outlet of the sample stream (s).

 From the bottom of column 2, a stream W is discharged containing predominantly alkyl tert-alkyl esters or a mixture thereof with hydrocarbons.

 According to FIG. 2, the synthesis is initially carried out in two or three series-connected reactors 1A, 1B and 1B, between which the reaction mixture is cooled. Further processing is carried out as described for FIG. 1.

Claims (3)

1. A method of producing alkyl tert-alkyl esters or mixtures thereof with hydrocarbons and / or alcohols by contacting mixtures of hydrocarbons containing at least tert-alkenes and non-tertiary alcohol (s) in the presence of acid catalysts, followed by separation, at least , parts of unreacted hydrocarbons from reaction products by distillation, characterized in that at least a portion of the stream taken from above and / or from the upper part of the distillation zone and containing predominantly unreacted hydrocarbons is subjected to They allow liquid phase contact with the catalyst in the additional reaction zone, possibly with the introduction of alcohol (s), at the outlet of which the temperature is maintained at least 10 ^° C lower than at the outlet of the first reaction zone, and the resulting reaction mixture is fed to the specified distillation the area below the output of the selected stream. 2. The method according to claim 1, characterized in that the contacting with the catalyst (s) preceding the rectification is carried out in two or more reaction zones and at least at the outlet of the latter, the temperature is maintained at least 10 ^° C lower than at the outlet of the first reaction zone. 3. The method according to claims 1 and 2, characterized in that when using two or more reaction zones prior to rectification, the temperature at least 10 ^° C higher than in the previous reaction zone is maintained at the exit from the additional reaction zone, and as distillation product at the distillation output a mixture containing at least dimers of tert-alkenes.

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