CN107501042B - Method for preparing isopropanol by hydrolyzing isopropyl acetate - Google Patents
Method for preparing isopropanol by hydrolyzing isopropyl acetate Download PDFInfo
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- CN107501042B CN107501042B CN201710707178.3A CN201710707178A CN107501042B CN 107501042 B CN107501042 B CN 107501042B CN 201710707178 A CN201710707178 A CN 201710707178A CN 107501042 B CN107501042 B CN 107501042B
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- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
- C07C29/09—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by hydrolysis
- C07C29/095—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by hydrolysis of esters of organic acids
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
- C07C29/74—Separation; Purification; Use of additives, e.g. for stabilisation
- C07C29/76—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment
- C07C29/80—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment by distillation
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- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
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Abstract
The invention discloses a method for preparing isopropanol by hydrolyzing isopropyl acetate, which mainly comprises the following steps: (1) mixing isopropyl acetate and water, and then feeding the mixture into a hydrolysis reactor; (2) the product after reaction enters a catalytic rectification tower under the condition of high pressure; acetic acid is extracted from the lower part of the tower; collecting the isopropanol material in an isopropanol enrichment region of the rectification section, and refining the isopropanol material in an isopropanol refining tower; (3) feeding the isopropanol material extracted from the self-catalytic rectifying tower into an isopropanol refining tower for refining, and operating the isopropanol refining tower under reduced pressure; a binary or ternary azeotrope formed by water, isopropyl acetate and part of isopropanol is extracted from the top of the tower, condensed and then enters a reflux tank; the product isopropanol is extracted from the lower part of the tower. The invention combines hydrolysis reaction and catalytic rectification, effectively improves the conversion rate of isopropyl acetate, ensures that the conversion rate of isopropyl acetate and the selectivity of isopropanol can reach more than 97 percent, and ensures that the purity of the isopropanol reaches more than 99 percent through pressure swing rectification separation.
Description
Technical Field
The invention relates to the technical field of chemical product preparation, in particular to a method for preparing isopropanol by hydrolyzing isopropyl acetate.
Background
The isopropanol is used as an organic solvent and an intermediate with excellent performance, has wide application in the fields of pesticides, printing ink, coatings, medicines, electronic products, daily chemicals, gasoline additives, organic synthesis and the like, and has good development and utilization prospects.
The industrial production method of isopropyl alcohol mainly comprises a propylene hydration method and an acetone hydrogenation method, wherein the former method can be divided into an indirect hydration method and a direct hydration method. The indirect hydration method is also called propene sulfuric acid hydration method, firstly, propene is dissolved in sulfuric acid and is subjected to esterification reaction to generate isopropyl sulfate and diisopropyl sulfate, esterification products are hydrolyzed to obtain crude isopropanol, and finally, the high-purity isopropanol is obtained through separation and refining. However, the method has the defects of complex flow, high sulfuric acid consumption, low product selectivity, serious equipment corrosion, high energy consumption and the like, and is gradually eliminated after the 80 s of the 20 th century. The direct hydration method refers to the method of adding propylene directly to water under the action of a catalyst to obtain isopropanol. Compared with the propene sulfuric acid hydration method, the method does not use sulfuric acid, so the method has no equipment corrosion problem and simple process flow; but the single-pass conversion rate of propylene is low, the energy consumption is high due to large circulation amount, and the requirement on the purity of the propylene raw material is high. The acetone hydrogenation method adopts a copper or zinc oxide catalyst or a nickel-based catalyst, and the acetone is hydrogenated to generate the isopropanol at the temperature of 70-200 ℃ and under the normal pressure. The selectivity of the method is 97%, the acetone conversion rate is 85-90%, the energy consumption is low, the corrosion of equipment is light, but the cost of the raw material acetone is high, and the problem of hydrogen source needs to be solved. The yield of the acetone hydrogenation process is generally lower than that of the propylene direct hydration process.
In addition to the mainstream process described above, the production of isopropyl alcohol can be performed by the following method. Chinese patent CN103880591A discloses a method for preparing isopropanol and ethanol by using propylene and acetic acid as raw materials, which comprises the steps of firstly, carrying out liquid-phase catalytic addition esterification on propylene and acetic acid under the action of a solid acid resin catalyst to synthesize isopropyl acetate, hydrogenating the obtained product under the action of a Cu-based catalyst to generate isopropanol and ethanol, and separating to obtain isopropanol and ethanol products; CN103657695A discloses a method for synthesizing isopropanol by catalyzing acetic acid hydrogenation at 150-180 ℃ by using phosphide as a main catalyst.
For propylene direct hydration method, acetone hydrogenation method and other hydrogenation methods, the problems of low conversion rate of raw materials, low selectivity, easy loss of catalyst, high reaction temperature, high reaction pressure and the like generally exist.
Chinese patent CN106673962A discloses a method for preparing isopropanol by hydrolyzing isopropyl acetate under the action of modified strong acid type cation exchange resin, wherein the conversion rate of isopropyl acetate and the selectivity of isopropanol can both reach more than 97%. However, the resin modification process according to this patent method is complicated and requires a long treatment time.
Disclosure of Invention
The invention aims to provide a method for preparing isopropanol, which has simple flow and high conversion rate of isopropyl acetate and selectivity of isopropanol.
In order to solve the technical problems, the invention provides a method for preparing isopropanol by hydrolyzing isopropyl acetate, which comprises the following steps:
(1) fully mixing isopropyl acetate and water, and then feeding the mixture into a hydrolysis reactor to react to obtain a quaternary mixture of isopropanol, water, acetic acid and isopropyl acetate;
(2) pressurizing the reacted quaternary mixture by a pump and then feeding the quaternary mixture into the catalytic rectifying tower from the lower part of the reaction section of the catalytic rectifying tower; the catalytic distillation column is operated at high pressure; acetic acid is extracted from the lower part of the tower; collecting the isopropanol material in an isopropanol enrichment region of the rectification section, and refining the isopropanol material in an isopropanol refining tower; extracting the ternary azeotrope of isopropanol-water-isopropyl acetate from the tower top, exchanging heat with tower kettle materials of an isopropanol refining tower, and then feeding the ternary azeotrope into a reflux tank; the isopropanol, the water and the isopropyl acetate are layered in a reflux tank to obtain a water phase and an isopropanol-isopropyl acetate organic phase, part of the organic phase is extracted and circulated back to a hydrolysis reactor, and part of the organic phase flows back to the tower from the top of the tower; the water phase part flows back to the tower above the reaction section, and part of the water phase part is circulated back to the hydrolysis reactor;
(3) feeding the isopropanol material extracted from the self-catalytic rectifying tower into an isopropanol refining tower for refining, and operating the isopropanol refining tower under reduced pressure; the binary or ternary azeotrope formed by water, isopropyl acetate and part of isopropanol is extracted from the top of the tower, condensed and then enters a reflux tank. The product isopropanol is extracted from the lower part of the tower; and layering the isopropanol, the water and the isopropyl acetate in the reflux tank to obtain a water phase and an isopropanol-isopropyl acetate organic phase, wherein part of the organic phase is extracted and circulated back to the hydrolysis reactor, part of the organic phase flows back to the tower, and the water phase is directly circulated back to the hydrolysis reactor.
Preferably, the operating conditions of the hydrolysis reactor in step (1) are: the volume space velocity of the mixture of isopropyl acetate and water is 1-3 h-1(ii) a The molar ratio of isopropyl acetate to water is 1-10: 1; reaction temperatureThe temperature is 50-200 ℃, and the adopted catalyst is one or more of cation exchange resin, heteropoly acid and mordenite.
Preferably, the catalytic distillation column in the step (2) is a high-pressure column, the operation pressure at the top of the column is 0.6-1.0 MPa, the temperature at the top of the column is 120-140 ℃, the reflux ratio of the water phase to the organic phase in the reflux tank is 1-5: 1, the number of the tower plates in the distillation section is 15-30, the number of the tower plates in the reaction section is 15-30, the number of the tower plates in the stripping section is 5-15, and the catalyst in the reaction section is one or more of cation exchange resin, heteropoly acid and mordenite.
Preferably, the isopropanol refining tower in the step (3) is a decompression tower, the operation pressure at the top of the tower is 0.02-0.06 MPa, the temperature at the top of the tower is 45-75 ℃, the reflux ratio of the water phase to the organic phase in a reflux tank is 1-5: 1, and the number of tower plates is 40-80.
The preparation method of the invention has the advantages that the conversion rate of the acetic acid isopropyl ester and the selectivity of the isopropanol can reach more than 97%, the purity of the acetic acid product is more than 95%, and the purity of the isopropanol is more than 99%.
The technical scheme of the invention has the following beneficial effects:
1. the hydrolysis reaction is combined with the catalytic rectification, so that the conversion rate of the isopropyl acetate is effectively improved, and the conversion rate of the isopropyl acetate and the selectivity of the isopropyl alcohol can reach more than 97 percent;
2. the sensitivity to pressure change is formed by azeotropes (isopropyl acetate-water-isopropanol ternary azeotrope, isopropyl acetate-water binary azeotrope, water-isopropanol binary azeotrope and isopropyl acetate-isopropanol binary azeotrope), and reaction products are effectively separated by using a two-tower pressure-variable rectification mode;
3. the purity of the acetic acid product is more than 95 percent, and the purity of the isopropanol is more than 99 percent;
4. the top discharge of the catalytic rectifying tower exchanges heat with the materials in the tower kettle of the isopropanol refining tower, namely the top heat of the catalytic rectifying tower is used as the heat source of the isopropanol refining tower, so that the utilization rate of energy is effectively improved;
5. the invention adopts hydrolysis reaction and two-tower pressure-variable rectification, has simple flow, simplified operation and low construction and equipment investment cost.
Drawings
FIG. 1 is a flow diagram of one embodiment of the present invention for the production of isopropanol by the hydrolysis of isopropyl acetate.
In the attached drawings, 1 is water, 2 is isopropyl acetate, 3 is a raw material mixer, 4 is a hydrolysis reactor, 5 is a catalytic rectifying tower, 6 is a catalytic rectifying tower reflux tank, 7 is a catalytic rectifying tower reboiler, 8 is catalytic rectifying tower top discharge, 9 is a line survey extraction of an isopropanol enrichment area of the catalytic rectifying tower, 10 is catalytic rectifying tower water reflux, 11 is catalytic rectifying tower return reactor circulating water, 12 is catalytic rectifying tower organic phase reflux, 13 is a catalytic rectifying tower return reactor organic phase, 14 is product acetic acid, 15 is an isopropanol rectifying tower, 16 is an isopropanol refining tower reboiler top condenser, 17 is an isopropanol refining tower reflux tank, 18 is an isopropanol refining tower (simultaneously, a catalytic rectifying tower top condenser), 19 is isopropanol refining tower return reactor circulating water, 20 is isopropanol refining tower organic phase reflux, 21 is an isopropanol refining tower return reactor organic phase, 22 is the product isopropanol.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, but the technical solutions do not limit the scope of the present invention.
Referring to fig. 1, isopropyl alcohol production was performed using commercially available isopropyl acetate having a purity of 99.5% as a raw material. Wherein the molar ratio of the water ester is 1-10: 1, the temperature of the hydrolysis reactor 4 is 50-200 ℃, the space velocity of the raw material is 1-3 h < -1 >, and heterogeneous solid acid is used as a catalyst. The quaternary mixture of isopropanol, water, acetic acid and isopropyl acetate obtained after the reaction enters the lower part of the reaction section of the catalytic rectification tower 5. The pressure at the top of the catalytic rectifying tower 5 is controlled according to 0.6-1.0 MPa, the operation temperature at the top of the catalytic rectifying tower is 120-140 ℃, the reflux ratio of a water phase to an organic phase is 1-5: 1, the number of theoretical plates at a rectifying section is 15-30, the number of theoretical plates at a reaction section is 15-30, the number of theoretical plates at a stripping section is 5-15, and a heterogeneous solid acid catalyst is used as a catalyst at the reaction section. Exchanging heat between the material 8 at the top of the catalytic rectifying tower 5 and the material at the bottom of the isopropanol refining tower 15 through an isopropanol refining tower reboiler 18, feeding the material into a reflux tank 6, extracting part of organic phase after water-ester layering, circulating the extracted organic phase back to the hydrolysis reactor 4, and refluxing part of the organic phase from the top of the tower into the tower; the aqueous phase part flows back into the tower above the reaction section, and part is circulated back to the hydrolysis reactor 4. The isopropanol-rich material 9 extracted from the isopropanol-rich region of the rectifying section of the catalytic rectifying tower 5 enters an isopropanol refining tower 15 for refining. The pressure at the top of the isopropanol refining tower 15 is controlled according to 0.02-0.06 MPa, the operating temperature at the top of the tower is 45-75 ℃, the reflux ratio of the water phase to the organic phase is 1-5: 1, and the number of theoretical plates is 40-80. The material at the top of the isopropanol refining tower 15 enters a reflux tank 17 after being condensed by a condenser 16, after water and ester are layered, part of the organic phase is extracted and circulated back to the hydrolysis reactor 4, part of the organic phase flows back to the tower, and the water phase 19 is directly circulated back to the hydrolysis reactor 4.
The following results are obtained through assay analysis: the purity of the product isopropanol 22 is 99.7%, and the purity of the acetic acid 14 extracted from the lower part of the catalytic distillation tower is 95.7%.
Specific parameters and product purities involved in specific examples are shown in table 1.
TABLE 1
Therefore, the invention combines hydrolysis reaction and catalytic rectification, effectively improves the conversion rate of isopropyl acetate, ensures that the conversion rate of isopropyl acetate and the selectivity of isopropyl alcohol can reach more than 97 percent, and ensures that the purity of the isopropyl alcohol reaches more than 99 percent through pressure swing rectification separation.
While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.
Claims (1)
1. A process for the preparation of isopropanol by hydrolysis of isopropyl acetate comprising the steps of:
(1) fully mixing isopropyl acetate and water, and then feeding the mixture into a hydrolysis reactor to react to obtain a quaternary mixture of isopropanol, water, acetic acid and isopropyl acetate;
(2) pressurizing the reacted quaternary mixture by a pump and then feeding the quaternary mixture into the catalytic rectifying tower from the lower part of the reaction section of the catalytic rectifying tower; the catalytic distillation column is operated at high pressure; acetic acid is extracted from the lower part of the tower; collecting the isopropanol material in an isopropanol enrichment region of the rectification section, and refining the isopropanol material in an isopropanol refining tower; extracting the ternary azeotrope of isopropanol-water-isopropyl acetate from the tower top, exchanging heat with tower kettle materials of an isopropanol refining tower, and then feeding the ternary azeotrope into a reflux tank; the isopropanol, the water and the isopropyl acetate are layered in a reflux tank to obtain a water phase and an isopropanol-isopropyl acetate organic phase, part of the organic phase is extracted and circulated back to a hydrolysis reactor, and part of the organic phase flows back to the tower from the top of the tower; the water phase part flows back to the tower above the reaction section, and part of the water phase part is circulated back to the hydrolysis reactor;
(3) feeding the isopropanol material extracted from the self-catalytic rectifying tower into an isopropanol refining tower for refining, and operating the isopropanol refining tower under reduced pressure; a binary or ternary azeotrope formed by water, isopropyl acetate and part of isopropanol is extracted from the top of the tower, condensed and then enters a reflux tank; the product isopropanol is extracted from the lower part of the tower; layering isopropanol, water and isopropyl acetate in a reflux tank to obtain a water phase and an isopropanol-isopropyl acetate organic phase, wherein part of the organic phase is extracted and circulated back to the hydrolysis reactor, part of the organic phase flows back to the tower, and the water phase is directly circulated back to the hydrolysis reactor;
the operating conditions of the hydrolysis reactor in the step (1) are as follows: the volume space velocity of the mixture of isopropyl acetate and water is 1-3 h-1(ii) a The molar ratio of isopropyl acetate to water is 1-10: 1; the reaction temperature is 50-200 ℃, and the adopted catalyst is one or more of cation exchange resin, heteropoly acid and mordenite;
the catalytic rectification tower in the step (2) is a high-pressure tower, the operation pressure of the tower top is 0.6-1.0 MPa, the temperature of the tower top is 120-140 ℃, the reflux ratio of a water phase to an organic phase in a reflux tank is 1-5: 1, the number of tower plates in a rectification section is 15-30, the number of tower plates in a reaction section is 15-30, the number of tower plates in a stripping section is 5-15, and a catalyst in the reaction section is one or more of cation exchange resin, heteropoly acid and mordenite;
in the step (3), the isopropanol refining tower is a decompression tower, the operation pressure at the top of the tower is 0.02-0.06 MPa, the temperature at the top of the tower is 45-75 ℃, the reflux ratio of the water phase to the organic phase in the reflux tank is 1-5: 1, and the number of tower plates is 40-80.
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| CN108947774B (en) * | 2018-07-18 | 2020-12-08 | 惠州宇新化工有限责任公司 | Method and device for separating isopropanol |
| KR102586512B1 (en) * | 2020-06-23 | 2023-10-06 | 주식회사 엘지화학 | Method for preraring isopropyl alcohol |
| KR20220151452A (en) * | 2021-05-06 | 2022-11-15 | 주식회사 엘지화학 | Method for preraring isopropyl alcohol |
| KR20220161920A (en) * | 2021-05-31 | 2022-12-07 | 주식회사 엘지화학 | Method for preraring isopropyl alcohol |
| KR20220161915A (en) * | 2021-05-31 | 2022-12-07 | 주식회사 엘지화학 | Method for preraring isopropyl alcohol |
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| CN106631684A (en) * | 2015-10-31 | 2017-05-10 | 湖南中创化工股份有限公司 | Method for preparing SBA(sec-butyl alcohol) through hydrolysis with sec-butyl acetate |
| CN106673962A (en) * | 2015-11-09 | 2017-05-17 | 中国石油化工股份有限公司 | Preparation method of isopropanol |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106631684A (en) * | 2015-10-31 | 2017-05-10 | 湖南中创化工股份有限公司 | Method for preparing SBA(sec-butyl alcohol) through hydrolysis with sec-butyl acetate |
| CN106673962A (en) * | 2015-11-09 | 2017-05-17 | 中国石油化工股份有限公司 | Preparation method of isopropanol |
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