WO2010020080A1

WO2010020080A1 - Process and apparatus for preparing adipic acid by catalytic air oxidation of cyclohexane

Info

Publication number: WO2010020080A1
Application number: PCT/CN2008/001809
Authority: WO
Inventors: 郭灿城; 徐庆利; 罗伟平; 刘强
Original assignee: Guo Cancheng; Xu Qingli; Luo Weiping; Liu Qiang
Priority date: 2008-08-18
Filing date: 2008-10-28
Publication date: 2010-02-25
Also published as: CN101337879B; CN101337879A

Abstract

Disclosed is a process and an apparatus for preparing adipic acid by catalytic air oxidation of cyclohexane. A cyclohexane containing dissolved 1-50 ppm monometalloporphyrin or mu-oxobimetalloporphyrin or their mixture with the salt or oxide of transitional metal as catalyst is oxidized for 45-120 minutes in multi-staged oxidation reactors with gas distributor. The mixture obtained by oxidation is fed into a flash separator, and the products with low boiling points of cyclohexane, cyclohexanol and cyclohexanone turn into gas and separate from adipic acid whose content exceeds 80%. The products with low boiling points are then recycled continuously for oxidation, and the products with high boiling points are separated and purified to obtain the purified adipic acid. The direct air oxidation of cyclohexane into adipic aicd is achieved. The conversion rate of cyclohexane reaches 95% and the yield of adipic acid reaches 70%.

Description

Process and special equipment for preparing adipic acid by catalytic air oxidation of cycloheximide

Technical field

The invention relates to a process and a special device for catalyzing the oxidation of cyclohexane to air to prepare adipic acid.

technical background

Chinese patent CN101186570 discloses a method for synthesizing adipic acid in two steps from cycloheximide. First, a cyclohexane oxidation mixture is obtained under the catalysis of a metal porphyrin, and then the mixture is oxidized by oxidation of cyclohexanone with nitric acid to obtain adipic acid. The disclosed scheme directly uses cyclohexane instead of using high cost cyclohexanone as a raw material, but still needs to use nitric acid as an oxidizing agent, but nitric acid may corrode the equipment and have environmental pollution problems; Chinese patent CN1556088A discloses an adjacent chlorine Iron porphyrin catalyzes the oxidation of cyclohexane to adipic acid by one step. The method can react for 8 hours at a concentration of 100-1000 _P pm chloroferric porphyrin and 25 atm. The mass yield of adipic acid can reach 21. 4%. However, the proposed scheme of the technology is a high-pressure closed system, which has a high catalyst concentration, a long reaction time, and many reaction by-products. Patent CN185075 (3⁄4 and patent CN1530358A) discloses a process and equipment for co-production of cyclohexanol, cyclohexanone and adipic acid by low-concentration metalloporphyrin biocatalytic cyclohexanone air oxidation. The product obtained by the technology is cyclohexanol and cyclohexanone. Mixture with adipic acid. Patent CN1535947A discloses a process for producing adipic acid by using a metal porphyrin biocatalytic air oxidation of cyclohexane, cyclohexanol, cyclohexanone or a mixture thereof in a gap reactor. When cyclohexanthene is used as a raw material, the conversion of cyclohexane is less than 40%, and the content of adipic acid in the product is less than 60%. The above-mentioned technique of catalyzing the oxidation of cyclohexanide using metal porphyrins uses air instead of corrosion equipment and brings environment. The polluting problem of nitric acid is used as an oxidant, but its oxidation product is a mixture of the intermediate products cyclohexanol and cyclohexanone and the target product adipic acid. It has been developed to catalyze the oxidation of cyclohexane by air catalyzed by metal porphyrin to obtain the target product. The process of diacids without intermediate products cyclohexanol and cyclohexanone has been the goal pursued by the process of synthesizing adipic acid from cycloheximide.

Summary of the invention

SUMMARY OF THE INVENTION It is an object of the present invention to provide another reaction process and apparatus for the direct oxidation of adipic acid from cyclohexane by a metal porphyrin as a catalyst. In the product, only the target product adipic acid is obtained without the intermediate products cyclohexanol and cyclohexanone, and the conversion of cyclohexanide and the yield of adipic acid are improved.

The process of the present invention comprises the following steps - (1) primary oxidation: 1-50 PPM of catalyst monometallic porphyrin or μ-oxybimetallic porphyrin or a transition metal salt or oxide thereof dissolved in cycloheximide Mixed catalyst, in a multi-stage oxidation reactor with a gas distributor, Into 5-12 atm of air or oxygen-rich, oxygen-poor air, control the reaction temperature is 140-160 ° C, cyclohexane oxidation for 45-120 minutes;

(2) Flash separation: The oxidation reaction mixture enters the flash-fc separator, flashing at a temperature of 78-155 ° C, a pressure of 0.1 to 1. 0 atm, and a low boiling point product in the oxidizing mixture. , cyclohexanol and cyclohexanone are converted to gases, separated from adipic acid and other high-boiling oxidation products succinic acid, valeric acid and succinic acid in an amount exceeding 80%;

(3) continuous cycle oxidation of low-boiling products: mixing the cyclohexane, cyclohexanol and cyclohexanone gases separated by flashing with cyclohexane containing a metal porphyrin catalyst, and then transferring them to an oxidation reactor for continuous cycle oxidation;

(4) Separation and purification of high-boiling oxidation products: Purification and separation according to the prior art to obtain a purified adipic acid product. a mixed catalyst composed of a 1-50 PPM catalyst monometallic porphyrin or a μ-oxybimetallic porphyrin metal porphyrin and a metal salt or oxide, a monometallic porphyrin or a μ-oxybimetallic porphyrin and a metal salt or The weight ratio of the oxide is 1: 20-100.

The monometallic porphyrin and the μ-oxybis metal porphyrin have the following structural formula:

The metal atom M in the formula (I) is one of the transition metal atoms Fe, Mn, Cr, Co, Cu, Zn, Ni or Ru, and the ligand X is one of acetic acid, acetylacetone, halogen or acid anion. Species

The metal atom M in the formula (Π), M ₂ is Fe, Mn or Cr.

The substituents R, R ₂ and R ₃ in the formula (I) and the formula (Π) are one of hydrogen or a hydrocarbon group, an alkoxy group, a hydroxyl group, a halogen group, an amine group, an amino group or a nitro group.

The special equipment of the present invention is a system composed of a multi-stage oxidation reactor and a flash separator connected in series, and the multi-stage oxidation reactor is a standard reaction kettle with 1-6 prior art mixers and air distributors. Or by 1-6 standard bubble column reactors or a combination thereof in series, the flash separator is a standard flash tank with a condensing device in the prior art.

In the product of the present invention, only the target oxidation product adipic acid is contained without the intermediate oxidation products cyclohexanol and cyclohexanone, and the direct air oxidation of cyclohexane to adipic acid is achieved. Compared with the oxidation of cyclohexanide with nitric acid to obtain adipic acid, the process does not use nitric acid, does not corrode equipment, and does not have environmental pollution caused by strong acid emissions. Compared with other existing gap reactors, the use of metal porphyrin biomimetic catalytic air oxidation of cyclohexane, cyclohexane conversion and adipic acid yield are greatly improved, cyclohexane conversion rate reaches 95%, adipic acid yield reaches 70%.

detailed description

Example 1

The reaction apparatus consisted of six standard reactors with a stirring and air distributor in series and a standard flash tank with a condensing unit. The production process is - at 15 CTC, a metal porphyrin in which 3 PP of formula (I) is dissolved, wherein R, = R ₂ - R ₃ = H, M = Co of cyclohexanyl, 8 atm by gas distributor The air is passed to the bottom of the first stirred reactor, and the reaction liquid overflowed from the upper part of the first stirred reactor is mixed with air and passed to the bottom of the second stirred reactor, from the upper part of the second stirred reactor. The overflowed reaction liquid and air were mixed, and the third stirred reactor was passed through λ, and then the fourth and fifth and sixth stirred reactors were sequentially passed. The cyclohexane flow rate was controlled so that the residence time was 50 minutes, and the air flow rate was controlled so that the tail oxygen content did not exceed 5%. The reaction mixture overflowing from the sixth stirred reactor enters the flash separation tank. 9 atm。 The pressure is reduced to 0. 9 atm. The products cyclohexanol, cyclohexanone and cyclohexanide are separated in a gaseous state by a flash tank separation outlet from the oxidation products adipic acid, succinic acid, valeric acid and succinic acid ester. After cyclohexanol, cyclohexanone and cyclohexane are cooled to a liquid state, they are mixed with cyclohexane containing a metal porphyrin catalyst and passed to a stirred reactor 1 for secondary oxidation. The above process is continuously cycled. The high boiling point oxidation product in the flash tank is cooled and purified according to the prior art to obtain adipic acid. The cyclohexane conversion was 95% and the adipic acid yield was 72%.

Example 2:

The special equipment consists of five standard bubble column reactors with air distributors in series and a standard flash tank with condensing unit. The production process is: under the 14CTC, a metal porphyrin dissolved in 10 PPM of formula (I), Rl=CH3, R2=R3=H, M=Fe cyclohexane, and 12 atm oxygenated 17% lean After passing through the gas distributor, the oxygen air is introduced into the bottom of the first bubble column reactor, and the reaction liquid overflowed from the upper part of the first bubble column reactor is mixed with oxygen-containing air containing 17% of oxygen and then introduced into the first At the bottom of the two bubbling reactors, the reaction liquid overflowing from the upper portion of the second reactor was mixed with air and then passed through the third, fourth and fifth standard bubble column reactors. The cyclohexane flow rate was controlled so that the residence time was 80 minutes, and the air flow rate was controlled so that the tail oxygen content did not exceed 5%. The reaction mixture overflowing from the fifth standard bubble column reactor enters the flash separation tank. The pressure was reduced to 0.3 atm while maintaining the flash tank temperature of 10 CTC. Cyclohexanol, cyclohexanone and cyclohexanil leave the flash tank in a gaseous state and are separated from the high boiling oxidation products adipic acid, succinic acid, valeric acid and succinate. The cyclohexanol, cyclohexanone and cyclohexane are cooled and mixed with a cyclohexanide containing a metal porphyrin catalyst to be passed through a second bubble column reactor for secondary oxidation. The above process is continuously cycled. The high boiling point oxidation product in the flash tank is cooled and purified to obtain adipic acid. The conversion of cyclohexane was 93%, and the yield of adipic acid was 70%.

Example 3: The reaction apparatus comprises two standard reactors with a stirring and air distributor in series, three bubble column reactors with an air distributor, and one flash tank. The production process is: under 16CTC, a metal porphyrin dissolved in 40 PPM of formula (II), R, = 0CH ₃ , R ₂ = RH, M = Mn of cyclohexane, and 5 atm of oxygen is 23%. The oxygen-enriched air is passed through the gas distributor and passed to the bottom of the first stirred reactor. The reaction liquid overflowed from the upper part of the first stirred reactor is mixed with oxygen-containing air containing 23% of oxygen and then passed to the second stirring. At the bottom of the reactor, the reaction liquid overflowing from the upper portion of the second stirred reactor was mixed with air, and then passed through the first and second and third bubbling reactors in sequence. The flow rate of the control loop was set to a residence time of 120 minutes, and the flow rate of the air was controlled so that the tail oxygen content did not exceed 5%. The reaction mixture overflowing from the third bubbling reactor enters the flash separation tank. 5 之间。 The pressure is reduced to 0. 5 atm. Cyclohexanol, cyclohexanone and cyclohexane leave the flash tank in a gaseous state and are separated from the high boiling point oxidation adipic acid, succinic acid, valeric acid and succinate. The cyclohexanol, cyclohexanone and cyclohexane are cooled and mixed with cyclohexane containing a metal porphyrin catalyst to pass through a first stirred reactor for secondary oxidation. The above process is continuously cycled. The high boiling point oxidation product in the flash tank is cooled and purified to obtain adipic acid. The conversion of cyclohexane was 96%, and the yield of adipic acid was 70%.

Example 4:

The reaction apparatus consisted of four reactors with a stirring and air distributor and a flash tank connected in series.

The production process is as follows: a metal porphyrin dissolved in 20 'ΡΡινϊ' structural formula (II) is introduced at 145 ° C, Cl, R ₂ = R ₃ =

H, M = Fe cyclohexane, 10 atm air is passed through the gas distributor to the bottom of the first stirred reactor, and the reaction liquid overflowed from the upper part of the first stirred reactor is mixed with air and then passed through The bottom of the two reactors was stirred, and the reaction liquid overflowing from the upper portion of the second stirred reactor was mixed with air and passed through a third stirred reactor. The reaction liquid overflowing from the upper portion of the third stirred reactor was mixed with air and passed through a fourth stirred reactor. The cyclohexane flow rate was controlled so that the residence time was 60 minutes, and the air flow rate was controlled so that the tail oxygen content did not exceed 5%. The reaction mixture overflowing from the fourth stirred reactor enters the flash separation tank. The pressure was increased to 1 atm while maintaining the flash tank temperature at 155 °C. Cyclohexanol, cyclohexanone and cyclohexane leave the flash tank in a gaseous state and are separated from the high boiling oxidation products adipic acid, succinic acid, valeric acid and succinate. The cyclohexanol, cyclohexanone and cyclohexane are cooled and mixed with cyclohexane containing a metal porphyrin catalyst to pass through a first stirred reactor for secondary oxidation. The above process is continuously cycled. The high boiling point oxidation product in the flash tank is cooled and purified to obtain adipic acid. The conversion of cyclohexane was 95%, and the yield of adipic acid was 71%. Example 5:

The reaction apparatus comprises a standard bubbling reactor with air distribution and three systems with an air distributor and a stirred standard reactor and a flash tank. The production process is as follows: a ring of 5 PPM of metal porphyrin of formula (I), R ₂ = OH, R, = R ₃ - H, = Mn and 100 PPM Co (OAc ) ₂ is introduced at 160 ° C. 12, 12 atm oxygen-containing 25% oxygen-enriched air is passed through the gas distributor to the bottom of the bubble column reactor, and the reaction liquid overflowed from the upper part of the bubble column reactor and oxygen-rich 25% oxygen After the air is mixed, it is passed to the bottom of the first stirred reactor, and the reaction liquid overflowing from the upper portion of the first stirred reactor is mixed with air and then passed through the second and third stirred reactors. The cyclohexane flow rate was controlled so that the residence time was 100 minutes, and the air flow rate was controlled so that the tail oxygen content did not exceed 5%. The reaction mixture overflowing from the stirred reactor 3 enters the flash separation tank. The pressure was reduced to 0. 4 atm ₀ cyclohexanol, cyclohexanone and cyclohexane left the flash tank in a gaseous state and with high boiling point oxidation products adipic acid, succinic acid, valeric acid Separated from succinate. The cyclohexanol, cyclohexanone and cyclohexanide are cooled and mixed with cyclohexane containing a metal porphyrin catalyst to be introduced into the bubbling reactor 1 to be subjected to secondary oxidation. The above process is continuously cycled. The high boiling point oxidation product in the flash tank is cooled and purified to obtain adipic acid. The cyclohexanyl conversion was 95% and the adipic acid yield was 75%.

Example 6:

The reaction apparatus comprises a system of five standard stirred reactors with air distributors and one standard flash tank in series. The production process is as follows: a metal porphyrin dissolved in 1 PPM of formula (I), Ι^= Ν0 ₂ , R ₂ = H, R ₃ =Br, M= Cu and 50 PPM of cobalt octoate Hexane, 9 atm of gas passing through the gas distributor is introduced into the bottom of the stirred reactor 1, and the reaction liquid overflowed from the upper part of the first stirred reactor is mixed with air and passed to the bottom of the second stirred reactor. The reaction liquid and the air overflowed from the upper portion of the second stirred reactor were mixed and passed to a third stirred reactor, and then passed through the reactor through the fourth and fifth stirred reactors in sequence. The cyclohexane flow rate was controlled so that the residence time was 45 minutes, and the air flow rate was controlled so that the tail oxygen content did not exceed 5%. The reaction mixture overflowing from the fifth stirred reactor enters the flash separation tank. 5 之间。 The pressure is reduced to 0. 7 atm. Cyclohexanol, cyclohexanone and cyclohexane leave the flash tank in a gaseous state and are separated from the high boiling oxidation products adipic acid, succinic acid, valeric acid and succinate. The cyclohexanol, cyclohexanone and cyclohexanide are cooled and mixed with cyclohexane containing a metal porphyrin catalyst to be stirred into the reactor 1 for secondary oxidation. The above process is continuously cycled. The high boiling point oxidation product in the flash tank is subjected to purification treatment to obtain adipic acid. Cyclohexane conversion 96%, the yield of adipic acid was 71%.

Example 7

The reaction apparatus comprises three stirred reactors with an air distributor and one flash tank in series.

The production process is as follows: a metal porphyrin dissolved in 60 PPM of formula (I) is introduced at 150 ° C, R _{l =} C ₃ H ₇₎ R ₃ = H, R ₂ = NH ₂ , M = Cr ring Alkane, 9 atm oxygen-containing 19% oxygen-depleted air is passed through the gas distributor to the bottom of the first stirred reactor, and the reaction liquid overflowing from the upper part of the first stirred reactor and oxygen-depleted 19% oxygen After the air is mixed, it is passed to the bottom of the second stirred reactor, and the reaction liquid overflowing from the upper portion of the second reactor is mixed with oxygen-containing air containing 19% of oxygen and then passed to a third stirred reactor. The cyclohexane flow rate was controlled so that the residence time was 70 minutes, and the air flow rate was controlled so that the tail oxygen content did not exceed 5%. The reaction mixture overflowing from the third stirred reactor enters the flash separation tank. The pressure was reduced to 0. 1 atmo cyclohexanol, cyclohexanone and cyclohexanone in a gaseous state from the flash tank and with high boiling point oxidation products adipic acid, succinic acid, Separation of valeric acid and succinate. The cyclohexanol, cyclohexanone and cyclohexane are cooled and mixed with cyclohexane containing a metal porphyrin catalyst to be stirred into the reactor 1 for secondary oxidation. The above process is continuously cycled. The high boiling point oxidation product in the flash tank is cooled and purified to obtain adipic acid. The cyclohexanyl conversion was 95% and the adipic acid yield was 75%.

Example 8

The reaction apparatus comprises four bubble column reactors with an air distributor and a flash tank in series.

The production process is as follows: a ring of 15 PPM of metal porphyrin of formula (I), C ₂ H ₅ , R ₃ = H, R ₂ =NMe ₂ , = Ni and 300 PPM Cu ₂ Cl _{2 is introduced} at 14 CTC. Hexane, 9 atm air is passed through the gas distributor to the bottom of the first bubbling reactor, and the reaction liquid overflowed from the upper part of the first bubbling reactor is mixed with air and then passed to a second bubbling reaction. At the bottom of the kettle, the reaction liquid overflowing from the upper portion of the second bubbling reactor was mixed with air and then passed through the third and fourth bubbling reactors. The cyclohexane flow rate was controlled so that the residence time was 50 minutes, and the air flow rate was controlled so that the tail oxygen content did not exceed 5%. The reaction mixture overflowing from the fourth bubbling reactor enters the flash separation tank. The pressure was reduced to 0. 2 at nio cyclohexanol, cyclohexanone and cyclohexanone in a gaseous state leaving the flash tank and with high boiling point oxidation products adipic acid, succinic acid, valeric acid and Separate separation. The cyclohexanol and cyclohexane cyclohexane are cooled and mixed with cyclohexane containing a metal porphyrin catalyst to be introduced into the bubbling reactor 1 to be subjected to secondary oxidation. The above process is continuously cycled. The boiling point oxidation product in the flash tank is cooled and purified to obtain adipic acid. The conversion of cyclohexane was 96%, and the yield of adipic acid was 72%.

Claims

Rights request

1. A process for catalyzing the oxidation of cyclohexanide to adipic acid, characterized in that it comprises the following steps:

(1) Primary oxidation: a catalyst containing 1-50 PPM of monometallic porphyrin or μ-oxybimetallic porphyrin or a mixed catalyst with a transition metal salt or oxide in a cyclohexane, with a gas distribution In the multi-stage oxidation reactor, 5-12 atm of air or oxygen-enriched, oxygen-poor air is introduced, the reaction temperature is controlled to be 140-160 ° C, and cyclohexanide is oxidized for 45-120 minutes;

(2) Flash separation: The oxidation reaction mixture enters the flash separator and is flashed at a temperature of 78-155, a pressure of 0.1 to 1. 0 atm, and the low boiling point product cyclohexane and cyclohexane in the oxidizing mixture The alcohol and cyclohexanone are converted to a gas, and are separated from adipic acid and other high-boiling oxidation products of succinic acid, valeric acid and succinic acid in an amount exceeding 80%;

(3) continuous cycle oxidation of low-boiling products: mixing the cyclohexane, cyclohexanol and cyclohexanone gas which are flash-separated with cyclohexanone containing a metal porphyrin catalyst, and then transferring it to an oxidation reactor for continuous cyclic oxidation;

(4) Separation and purification of high-boiling oxidation products: Purification and separation according to the prior art to obtain a purified adipic acid product.

2 . The process for preparing adipic acid by catalytic air oxidation of cyclohexane according to claim 1 , wherein the 1-50 PPM catalyst is monometallic porphyrin or oxybimetallic η′porphyrin with metal salt or oxidized In the mixed catalyst of the composition, the weight ratio of the monometallic porphyrin or the μ-oxybimetallic porphyrin to the metal salt or oxide is 1:20-100.

The process for preparing adipic acid by catalytic air oxidation of cyclohexanone according to claim 1, wherein the metal porphyrin and the μ-oxybis metal porphyrin have the following structural formula:

The metal atom M in the formula (II), M ₂ is Fe, Mn or Cr;

The substituents R, R ₂ and R ₃ in the formula (I) and the formula (Π) are one of hydrogen or a hydrocarbon group, a decyloxy group, a hydroxyl group, a halogen group, an amine group, an amino group and a nitro group.

4. A special apparatus for catalyzing the oxidation of cyclohexane to prepare adipic acid, characterized in that it is a system consisting of a multistage oxidation reactor and a flash separator connected in series, and the multistage oxidation reactor is composed of 1 -6 standard reactors with agitation and air distributors or from 1-6 standard bubble column reactors or a combination of them in series, the flash separator is a standard flash with a condensing unit tank.