RU2286333C1 - Method for preparing esters - Google Patents

Abstract

FIELD: petrochemical industry, chemical technology.

SUBSTANCE: invention relates to a method for combined synthesis of methyl-tert.-butyl and methylisobutyl esters that are used as high-octane additive to motor fuels. Method involves treatment of isobutylene-containing fraction with methanol in liquid phase at heating, under pressure, in the presence of sulfocation-exchange resin in H⁺-form as a catalyst. Then reaction products are separated in fractionating column wherein dimethyl ether and isobutanol are added additional to the raw composition in the following mole ratio of components: methanol : isobutylene : dimethyl ether : isobutanol = (0.71-0.82):1:(0.21-0.33):(0.21-0.33), respectively, and treated in liquid phase. Temperature in the reaction zone is maintained in the range 50-70°C and pressure - 1.6 mPa. Invention provides the possibility for simultaneous synthesis of different esters and simplifying the process.

EFFECT: improved preparing method.

1 tbl, 2 dwg, 5 ex

Description

The invention relates to the petrochemical industry, in particular to a method for the joint production of methyl tert-butyl and dimethyl ethers, which are used as a high-octane additive to motor fuels.

Known from the patent literature are methods for producing methyl tert-butyl ether (MTBE) by directly passing a mixture of methanol and a C ₄ hydrocarbon fraction containing isobutylene through a catalyst sulfonation catalyst bed [Patent GB 1506596, cl. C 07 C 1980, USSR patent 867295 class. C 07 C 43/04, 1981, patent US 4324924, class. C 07 C 41/06, 1982]. The process is carried out in the liquid phase at elevated pressure and a temperature of 30-100 ° C. The molar ratio of methanol to isobutylene is 2.0-1.0: 1. The reaction mixture leaving the reactor containing the spent C ₄ hydrocarbon fraction, methanol and MTBE is sent for distillation with a column efficiency of 14 tons, where a hydrocarbon azeotrope with methanol is distilled off at a pressure of 0.6-0.8 MPa, and MTBE is isolated from cube columns.

Common features of the known technical solutions and the claimed invention is the passage of a mixture of methanol and a fraction of hydrocarbons C ₄ containing isobutylene through a catalyst sulfonic cation exchanger layer, the process in the liquid phase under elevated pressure and heating, rectification of the reaction mixture to isolate the target product (MTBE).

The disadvantages of the known methods for producing ethers include the lack of the possibility of co-production of a mixture of ethers (MTBE and MIBE), a significant consumption of methanol.

From [Patent RU 2063398 cl. C 07 C 43/04, 41/06, 1996] a method is known for producing MTBE by reacting an isobutylene-containing fraction of C ₄ hydrocarbons with methanol in a liquid phase under pressure in the presence of a sulfocationionite catalyst in the H-form in two reaction zones, with a methanol to molar ratio isobutylene in the initial mixture of 1.01: 1, 0 to an isobutylene conversion in the first reaction zone of 95-99% and at relatively low reaction temperatures, varying from 25-40 to 80-110 ° C in the first reaction zone and in the range from 25-40 to 45-58 ° C in the second reaction zone. Moreover, the feed mixture supplied to the first reaction zone contains an excess of methanol, and the substances that did not react in the first reaction zone, obtained after separation of MTBE in a distillation column, are fed into the second reaction zone.

The objective of this invention is to develop a method for the joint production of methyl tertiary butyl ether (MTBE) and methyl isobutyl ether (MIBE) when isobutylene and methanol are used as raw materials in the esterification reaction and dimethyl ether (DME) with isobutanol in the transesterification reaction.

The technical result of the invention is:

- joint receipt of MTBE and MIBE in the same reaction zone,

- simplification of the process,

- a significant reduction in methanol consumption,

- an increase in the total yield of MTBE and MIBE esters,

- improving the physico-chemical properties of the resulting mixture of esters, as an octane-raising additive to motor fuels,

- increase their positive impact on the octane number of motor fuels.

The technical result in the method for producing esters by treating the isobutylene-containing fraction with methanol in the liquid phase under pressure by heating and in the presence of a sulfocationionite catalyst in the H-form, by separating the esters in the distillation column, is achieved due to the fact that dimethyl ether (DME) is additionally introduced into the feed composition. and isobutanol, the process is carried out in one reaction zone, with the following molar ratio of reactants in the initial mixture: methanol: isobutylene: dimethyl ether: isobutanol equal to 0.82-0.71: 1: 0.21-0.33: 0.21 -0.33 respectively but. The temperature in the reaction zone is maintained in the range of 50-70 ° C, the pressure is 1.6 MPa.

A comparative analysis of the prototype and the claimed invention shows that the common features are the treatment with methanol of an isobutylene-containing fraction, which is carried out in the liquid phase, under pressure, with heating and in the presence of a sulfocationite catalyst in the H-form in the reaction zone, separation of the target product in a distillation column.

The difference of the invention from the prototype is that

- the composition of the raw materials further include dimethyl ether (DME) and isobutanol;

the molar ratio of reactants methanol: isobutylene: DME: isobutanol is 0.82-0.71: 1: 0.21-0.33: 0.21-0.33;

- the temperature in the reaction zone is maintained in the range of 50-70 ° C, and the pressure is 1.6 MPa;

- the esterification reaction is carried out in one reaction zone;

- the reaction products are separated in one column.

The prior art does not know the influence of distinguishing features on the achievement of the claimed technical result, namely, the joint production of MTBE and MIBE in one reactor and the isolation of reaction products in one column are not described.

Carrying out the proposed process according to a single-reactor scheme and with single-column separation of reaction products provides a simplification of the technology, a significant reduction in methanol consumption and an increase in the yield of total esters. The degree of conversion of isobutylene reaches 95-99%, the degree of conversion of isobutanol is 91-92%.

The claimed technical solution can be implemented in an industrial environment, and a mixture of the resulting esters can be used as octane boosting additives for motor fuels.

The invention is illustrated by the following examples.

The process is carried out on a continuous installation. Schematic diagrams of the implementation of the method for producing esters of the prototype and the proposed technical solution are presented in figure 1 and 2, respectively. According to the prototype of FIG. 1, methanol (stream 1) and butane-butylene fraction (BBP) (stream 2) are pumped in a predetermined ratio into tank I. The resulting mixture from tank I (stream 3) is fed to reactor II filled with sulfocationic catalyst in Н- form. The reaction mixture exiting reactor II (stream 4) is sent to distillation column III, on top of which the spent BBP is discharged (stream 5), and the reaction product (stream 6) of MTBE is removed by cube.

Methanol (GOST 2222-78) and the butane-butylene fraction of catalytic cracking are used as starting reagents. As a catalyst, sulfocationionite in H-form is used, for example, KU-2-8 (GOST 20298-74) or others.

According to the proposed technical solution of FIG. 2, methanol (stream 1), BBP (stream 2), DME fraction (stream 3) and isobutanol (stream 4) are injected in predetermined proportions into vessel I. The resulting mixture (stream 5) is fed to reactor II, filled with sulfonated catalyst in the H-form. The reaction mixture exiting reactor II (stream 6) is sent to distillation column III, on top of which the spent BBP is discharged (stream 7), and the target product (stream 8) is removed by cube — a mixture of MTBE and MIBE.

Methanol (GOST 2222-78), catalytic cracking BBP, DME fraction of methanol production and isobutanol (GOST 9536-79) are used as starting reagents. The catalyst used is sulfocationionite in the H-form, for example, KU-2-8 (GOST 20298-74).

Example 1 (prototype).

Methanol (stream 1) is pumped into tank I in an amount of 748 g. BBP with an isobutylene content of 16.2% by weight. (stream 2) is pumped into the tank I in an amount of 8000 g. The resulting raw material mixture (8748 g) (stream 3) composition, wt.%: C ₄ hydrocarbons - 76.64; isobutylene - 14.81; methanol - 8.55 with a molar ratio of methanol: isobutylene 1.01: 1.00 continuously fed into reactor II with a catalyst volume of 170 cm ³ at a speed of 178.5 g / h (306 cm ³ / h), i.e. with a bulk velocity of 1.8 h ^-1 . In a reactor with an electrically heated jacket, an inlet temperature of 50 ° C. is maintained, and a pressure of 1.6 MPa is maintained at an outlet of 60 ° C. Coming out of the reactor II mixture (stream 4) of the composition, wt.%: MTBE - 22.00; methanol - 0.54; isobutylene - 0.81; trimethylcarbinol (TMK) - 0.01; DME - 0.01; C ₈ olefins - traces; C ₄ - 76.63 hydrocarbons are sent to distillation column III, on top of which distillate (stream 5) is taken in the amount of 139.4 g / h of composition wt.%: methanol - 0.70; isobutylene - 1.02; MTBE - 0.21; hydrocarbons - C ₄ 98.07; TMK - traces; DME - traces. From the cube of distillation column III, a product (stream 6) is taken in an amount of 39.1 g / h of composition, wt.%: MTBE - 99.79; TMK - 0.06; hydrocarbons C ₄ - 0.14; C ₈ olefins are traces. The output of the bottoms product is 1914.8 g or 21.89 wt.% For raw materials.

Example 2 (according to the present technical solution).

Methanol (stream 1) in an amount of 573 g, BBP with an isobutylene content of 16.2 wt.% (Stream 2) in an amount of 7609 g, DME fraction with a methanol content of 1.17 wt.% (Stream 3) in an amount of 231 g and isobutanol (stream 4) in an amount of 335 g is pumped into tank I. The resulting raw material mixture (8748 g) from tank I (stream 5) of the composition, wt.%: C ₄ hydrocarbons - 72.89; isobutylene - 14.09; methanol - 6.58; DME - 2.61; isobutanol - 3.83, the molar ratio of methanol: isobutylene: DME: isobutanol 0.82: 1.00: 0.21: 0.21 continuously fed into the reactor II with a catalyst volume of 170 cm ³ at a speed of 180.2 g / hour ( 306 cm ³ / h), i.e. with a bulk velocity of 1.8 h ^-1 . In a reactor with an electrically heated jacket, an inlet temperature of 50 ° C., an outlet temperature of 70 ° C. and a pressure of 1.6 MPa are maintained. Coming out of the reactor II mixture (stream 6) of the composition, wt.%: MTBE - 20.92; methanol - 0.46; isobutylene - 0.75; TMK - 0.03; DME - 0.47; C ₄ hydrocarbons 72.89; isobutanol - 0.36; MIBE - 4.12 is sent to distillation column III, on top of which distillate (stream 7) is taken in an amount of 134.6 g / h of composition, wt.%: C ₄ hydrocarbons - 97.51; DME - 0.63; methanol 0.61; isobutylene - 1.01; MTBE - 0.20; MIBE - 0.02. From the cube of distillation column III, a product (stream 8) is taken in an amount of 45.6 g / h of composition, wt.%: MTBE - 82.17; TMK - 0.04; MIBE - 16.23; hydrocarbons C ₄ - 0.12; isobutanol - 1.44. The sum of MTBE and MIBE, wt.%, 98,41. The output of the bottoms product is 2211.6 g or 25.28 wt.% For raw materials. The rate of selection of esters compared with the prototype increased from 39.1 to 45.6 g / hour or 14.3% rel. In the transesterification of DME with isobutanol due to the formation of additional methanol, its amount in the initial mixture was reduced from 748 to 573 g, or by 23.4 wt.%.

Example 3 (according to the present technical solution).

Methanol (stream 1) in an amount of 525 g, BBP with an isobutylene content of 16.2 wt.% (Stream 2) in an amount of 7507 g, DME fraction with a methanol content of 1.17 wt.% (Stream 3) in an amount of 276 g, isobutanol (stream 4) in an amount of 440 g is pumped into tank I. The resulting raw material mixture (8748 g) from tank I (stream 5) of the composition, wt.%: C ₄ hydrocarbons - 71.91; isobutylene - 13.90; methanol - 6.04; DME - 3.12; isobutanol - 5.03, the molar ratio of methanol: isobutylene: DME: isobutanol 0.76: 1.00: 0.27: 0.27 is continuously fed into reactor II with a catalyst volume of 170 cm ³ at a rate of 180.7 g / hour ( 306 cm ³ / h), i.e. with a bulk velocity of 1.8 h ^-1 . In a reactor with an electrically heated jacket, an inlet temperature of 50 ° C., an outlet temperature of 70 ° C. and a pressure of 1.6 MPa are maintained. Coming out of the reactor II mixture (stream 6) of the composition, wt.%: MTBE - 20.64; methanol - 0.48; isobutylene - 0.74; TMK - 0.03; DME - 0.31; C ₄ hydrocarbons - 71.91; isobutanol - 0.48; MIBE - 5.41 is sent to distillation column III, on top of which distillate (stream 7) is taken in an amount of 133.0 g / h of composition, wt.%: C ₄ hydrocarbons - 97.67; DME - 0.41; methanol 0.65; isobutylene - 1.01; MTBE - 0.20; MIBE - 0.03. From the cube of distillation column III, a product (stream 8) is taken in an amount of 47.7 g / h of composition, wt.%: MTBE - 77.62; TMK - 0.05; MIBE - 20.41; hydrocarbons C ₄ - 0.11; isobutanol - 1.81. The sum of MTBE and MIBE 98.04 wt.%. The output of the bottoms product is 2309.8 g or 26.40 wt.% For raw materials. The rate of selection of esters compared with the prototype increased from 39.1 g / hour to 47.7 g / hour or 18.1% rel. When transesterification of DME with isobutanol due to the formation of additional methanol, its initial amount in the mixture is reduced in comparison with the prototype from 748 to 525 g or 29.8% rel.

Example 4 (according to the present technical solution).

Methanol (stream 1) in an amount of 480 g, BBP with an isobutylene content of 16.2 wt.% (Stream 2) in an amount of 7410 g, DME fraction in an amount of 329 g (stream 3) with a DME content of 98.83 wt.%; methanol 1.17 wt.%, isobutanol (stream 4) in an amount of 529 g is pumped into tank I. The resulting feed mixture (8748 g) from tank I (stream 5) of the composition, wt.%: C ₄ hydrocarbons - 70.98; isobutylene - 13.72; methanol - 5.53; DME - 3.72; isobutanol - 6.05, the molar ratio of methanol: isobutylene: DME: isobutanol 0.71: 1.00: 0.33: 0.33 is continuously fed into reactor II (catalyst volume 170 cm ³ ) at a speed of 181.2 g / hour (306 cm ³ / hour), i.e. with a bulk velocity of 1.8 h ^-1 . In the reactor with an electrically heated jacket, the inlet temperature is maintained at 50 ° C, at the outlet 70 ° C and a pressure of 1.6 MPa. Coming out of the reactor II mixture (stream 6) composition, wt.%: MTBE - 20.37; methanol - 0.46; isobutylene - 0.73; TMK - 0.04; DME - 0.33; C ₄ hydrocarbons - 70.98; isobutanol - 0.57; MIBE - 6.51 is sent to distillation column III, on top of which distillate (stream 7) is taken in an amount of 131.7 g / h of composition, wt.%: C ₄ hydrocarbons - 97.64; DME - 0.46; methanol - 0.64; isobutylene - 1.00; MTBE - 0.20; MIBE - 0.04. From the cube of distillation column III, a product is taken in an amount of 49.5 g / h of composition, wt.%: MTBE - 74.02; TMK - 0.05; MIBE - 23.72; isobutanol - 2.10; hydrocarbons C ₄ - 0.10. The sum of MTBE and MIBE, wt.%, 97.74. The output of the bottoms product is 2390.8 g or 27.33 wt.% For raw materials. The rate of selection of esters compared with the prototype increased from 39.1 to 49.5 g / hour or 21.1% rel. During the transesterification of DME with isobutanol due to the formation of additional methanol, its amount in the initial mixture was reduced from 748 to 480 g, or by 35.83% rel.

Example 5 (according to the present technical solution).

Methanol (stream 1) in an amount of 439 g, BBP with an isobutylene content of 16.2 wt.% (Stream 2) in an amount of 7297 g, DME fraction in an amount of 392 g (stream 3) with a DME content, wt.%: 98.83 ; methanol - 1.17, isobutanol (stream 4) in an amount of 624 g is pumped into tank I. The resulting raw material mixture (8748 g) from tank I (stream 5) of the composition, wt.%: C ₄ hydrocarbons - 69.90; isobutylene - 13.51; methanol - 5.02; DME - 4.44; isobutanol - 7.13, the molar ratio of methanol: isobutylene: DME: isobutanol 0.66: 1.00: 0.40: 0.40 is continuously fed into reactor II (catalyst volume 170 cm ³ ) at a speed of 181.8 g / hour (306 cm ³ / hour), i.e. with a bulk velocity of 1.8 h ^-1 . In the reactor with an electrically heated jacket, the inlet temperature is maintained at 50 ° C, at the outlet 70 ° C and a pressure of 1.6 MPa. Coming out of the reactor II mixture (stream 6) composition, wt.%: MTBE - 20.05; methanol - 0.54; isobutylene - 0.71; TMK - 0.04; DME - 0.44; C ₄ hydrocarbons 69.86; isobutanol - 0.68; MIBE - 7.68 is sent to distillation column III, on top of which distillate (stream 7) is taken in the amount of 130.4 g / h of composition, wt.%: C ₄ hydrocarbons - 97.37; DME - 0.61; methanol - 0.75; isobutylene - 0.99; MTBE - 0.20; MIBE - 0.05. From the cube of distillation column III, a product is taken in an amount of 51.4 g / h of composition, wt.%: MTBE - 70.41; TMK - 0.06; MIBE - 27.03; isobutanol - 2.39; hydrocarbons C ₄ - 0.10. The sum of MTBE and MIBE, wt.%, 97.44. The output of the bottoms product is 2773.7 g or 28.28 wt.% For raw materials. The rate of selection of esters compared with the prototype increased from 39.1 to 51.4 g / hour or 24.0% rel. During the transesterification of DME with isobutanol due to the formation of additional methanol, its amount in the initial mixture was reduced from 748 to 439 g, or by 41.3% rel.

Example 6 (according to the present technical solution).

Methanol (stream 1) in an amount of 400 g, BBP with an isobutylene content of 16.2 wt.% (Stream 2) in an amount of 7212 g, DME fraction in an amount of 442 g (stream 3) with a DME content, wt.% 98.83; methanol - 1.17, isobutanol (stream 4) in an amount of 694 g is pumped into tank I. The resulting raw mix (8748 g) from tank I (stream 5) of the composition, wt.%: C ₄ hydrocarbons - 69.09; isobutylene - 13.36; methanol - 4.63; DME - 4.99; isobutanol - 7.93, the molar ratio of methanol: isobutylene: DME: isobutanol 0.61: 1.00: 0.46: 0.45 is continuously fed into reactor II (catalyst volume 170 cm ³ ) at a rate of 182.1 g / hour (306 cm ³ / hour), i.e. with a bulk velocity of 1.8 h ^-1 . In the reactor with an electrically heated jacket, the inlet temperature is maintained at 50 ° C, at the outlet 70 ° C and a pressure of 1.6 MPa. Coming out of the reactor II mixture (stream 6) composition, wt.%: MTBE - 19.83; methanol - 0.49; isobutylene - 0.70; TMK - 0.05; DME - 0.56; C ₄ hydrocarbons - 69.09; isobutanol - 0.75; MIBE - 8.54 is sent to distillation column III, on top of which distillate (stream 7) is taken in an amount of 129.30 g / h of composition, wt.%: C ₄ hydrocarbons - 97.25; DME - 0.78; methanol - 0.69; isobutylene - 0.99; MTBE - 0.20; MIBE - 0.05. From the cube of distillation column III, a product is taken in the amount of 52.8 g / h of composition, wt.%: MTBE - 67.92; TMK - 0.06; MIBE - 29.32; isobutanol 2.60; hydrocarbons C ₄ - 0.10. The sum of MTBE and MIBE, wt.% 97,24. The yield of bottoms product is 2536.1 g or 28.99 wt.% For raw materials. The rate of selection of esters compared with the prototype increased from 39.1 to 52.8 g / hour or 24.0% rel. During transesterification of DME with isobutanol due to the formation of additional methanol, its amount in the initial mixture was reduced from 748 to 400 g, or by 46.5% rel.

The obtained MTBE esters (example 1) and a mixture of MTBE and MIBE (examples 2, 3, 4, 5, 6) were combined with reforming gasoline. The results presented in the table show that the mixture of esters according to examples 2, 3 and 4 as an octane enhancing additive is not inferior in efficiency to pure MTBE. The mixture of esters in examples 5 and 6, containing a high content of isobutanol, in the compositions of the gasoline reforming has a reduced rate.

The increase in the octane number of reforming gasoline compositions (OR 85.2 / 94.6 and 85.0 / 95.01 by the motor method / by the research method) with ethers Example No. Gasoline specifications Octane gain, item MM THEM one Reform Gasoline with 15% MTBE 1.9 3.2 2 Reforming gasoline with the addition of 15% of the amount of ethers (MTBE + MIBE) 2.2 3.8 3 Reforming gasoline with the addition of 15% of the amount of ethers (MTBE + MIBE) 2.2 3.8 four Reforming gasoline with the addition of 15% of the amount of ethers (MTBE + MIBE) 2,3 4.0 5 Reforming gasoline with the addition of 15% of the amount of ethers (MTBE + MIBE) 1.7 2.0 6 Reforming gasoline with the addition of 15% of the amount of ethers (MTBE + MIBE) 2.2 2,5

Claims (1)

A method for producing esters, including the treatment with methanol of an isobutylene-containing fraction, which is carried out in the liquid phase under heating under pressure in the presence of a catalyst-sulfocationite in the H-form, separation of the reaction products in a distillation column, characterized in that dimethyl ether and isobutanol are additionally introduced into the feedstock the following molar ratio of components: methanol: isobutylene: dimethyl ether: isobutanol, respectively 0.82-0.71: 1: 0.21-0.33: 0.21-0.33, the temperature in the reaction zone is maintained in the range of 50-70 ° C, and pressure 1.6 MPa.

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