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CN-122010716-A - Method and system for preparing adipic acid by oxidizing cyclohexane

CN122010716ACN 122010716 ACN122010716 ACN 122010716ACN-122010716-A

Abstract

The invention provides a method and a system for preparing adipic acid by oxidizing cyclohexane. The method comprises the steps of (1) enabling cyclohexane to be in contact with ozone-containing gas to obtain a material I, and (2) enabling the material I to be in oxidation reaction with O 2 -containing gas to obtain a adipic acid-containing product material II. The method is simple, efficient, green and environment-friendly, and the obtained adipic acid provides excellent raw materials for polyester production.

Inventors

  • CHEN YANXIN
  • GAO XIAOCHEN
  • ZHANG HONGYU
  • Chu Qinzhong
  • YAO QUANMING
  • LI JIAN

Assignees

  • 中国石油化工股份有限公司
  • 中石化（上海）石油化工研究院有限公司

Dates

Publication Date
20260512
Application Date
20241111

Claims (10)

  1. 1. A method for preparing adipic acid by oxidation of cyclohexane, comprising: (1) Cyclohexane is contacted with ozone-containing gas to obtain a material I; (2) And (3) carrying out an oxidation reaction on the material I and O 2 -containing gas to obtain a adipic acid-containing product material II.
  2. 2. The method of claim 1, wherein the step of determining the position of the substrate comprises, The ozone-containing gas has a volume concentration of ozone of 0.1-8.0%, preferably 0.5-5.0%, and/or The mass ratio of ozone to cyclohexane in the ozone-containing gas is (0.005-0.1): 1.
  3. 3. A method according to claim 1 or 2, characterized in that, The temperature of the contact is 10-80 ℃, preferably 40-60 ℃, and/or The contact time is 10-120min, preferably 10-60min.
  4. 4. A process according to any one of claims 1 to 3, wherein the oxidation reaction is carried out in the presence of a catalyst and a solvent; preferably, the solvent is selected from acetic acid.
  5. 5. The method of claim 4, wherein the step of determining the position of the first electrode is performed, The catalyst is selected from metal salt catalysts; preferably, the metal element in the metal salt catalyst is selected from one or more of copper, manganese or cobalt; Preferably, the metal salt is acetate of a metal element; preferably, the catalyst is a mixture of copper acetate, manganese acetate and cobalt acetate; Preferably, the mass ratio of the copper element, the manganese element and the cobalt element in the catalyst is (5-10): (1-5): 1.
  6. 6. The method according to any one of claims 1-5, wherein the oxidation reaction comprises the steps of: s1, mixing a catalyst and a solvent to obtain a catalyst solution; S2, carrying out oxidation reaction on the catalyst solution, the material I and the gas containing O 2 ; preferably, the mass ratio of the catalyst solution to the mass I is (1.5-8): 1, and/or The mass concentration of the catalyst in the catalyst solution is 0.05-5%.
  7. 7. The method according to any one of claims 1 to 6, wherein, The mass ratio of the O 2 -containing gas to the material I is (5-15): 1, and/or The volume content of O 2 in the O 2 -containing gas is 10-25%, preferably 15-25%.
  8. 8. The method according to any one of claims 1 to 7, wherein the temperature of the oxidation reaction is 85-110 ℃, and/or The pressure of the oxidation reaction is 1.5-5MPa, and/or The oxidation reaction time is 0.5-2h.
  9. 9. A system for preparing adipic acid by oxidation of cyclohexane for use in the process of any one of claims 1-8, the system comprising: a cyclohexane feed tank; The gas-liquid contact device is connected with the cyclohexane raw material tank so as to enable cyclohexane to be in contact with ozone-containing gas to obtain a material I; and the reactor is connected with the gas-liquid contact device so as to enable the material I and the gas containing O 2 to carry out oxidation reaction to obtain a product material II containing adipic acid.
  10. 10. The system of claim 9, further comprising a catalyst tank coupled to the reactor such that the oxidation reaction is performed in the presence of a catalyst solution; Preferably, the system further comprises a discharge vessel connected to the reactor for receiving material II.

Description

Method and system for preparing adipic acid by oxidizing cyclohexane Technical Field The invention relates to the technical field of chemical industry, in particular to a method and a system for preparing adipic acid by oxidizing cyclohexane. Background Adipic acid, also known as fatty acid, is an important organic diacid that can undergo a salt formation reaction, an esterification reaction, an amidation reaction, etc., and can be polycondensed with diamine or glycol to form a high molecular polymer, etc. Adipic acid plays an important role in chemical industry, organic synthesis industry, medicine, lubricant manufacturing and the like. In particular, adipic acid can be used for synthesizing nylon 66 and producing polyurethane, can also be used as food acidulant for keeping food fresh and stable, and can also be used for producing perfume and dye. In 1937, the DuPont company of America first achieved the commercial production of adipic acid by oxidizing cyclohexanol (produced by hydrogenation of phenol) with nitric acid. In the 60 s, the industry gradually changes the cyclohexane oxidation method, namely, firstly, preparing intermediate products of cyclohexanone and cyclohexanol (namely, ketol oil, also called KA oil) from cyclohexane, and then, carrying out nitric acid or air oxidation on the KA oil. Cyclohexane molecules are used as a rigid ring, the difficulty of oxidative ring opening is extremely high, particularly, air with poor oxidizing property is used as an oxidant, the reaction initiation is difficult, once the reaction is started, the free radical reaction chain is difficult to control, various byproduct impurities are easy to generate, and the selectivity of the adipic acid as a target product is difficult to improve. If hydrogen peroxide is directly used as an oxidant, although the reaction efficiency can be improved, the hydrogen peroxide is easy to decompose at high temperature, the utilization rate is lower, cyclohexane is easy to explode, the generation cost is increased, and the safety of the system is greatly reduced. Therefore, the conversion efficiency of cyclohexane direct feeding in the prior art is not high, higher reaction temperature and longer reaction time are generally required, the adipic acid yield is improved through a large amount of cyclohexane circulation, the impurity byproducts generated by the reaction are difficult to separate, the separation energy consumption is high, and the atomic economy is poor. Disclosure of Invention The invention aims to overcome the defects in the prior art and provides a method and a system for preparing adipic acid by oxidizing cyclohexane. The method is simple, efficient, green and environment-friendly, and the obtained adipic acid provides excellent raw materials for polyester production. In a first aspect, the present invention provides a process for preparing adipic acid by oxidation of cyclohexane comprising: (1) Cyclohexane is contacted with ozone-containing gas to obtain a material I; (2) And (3) carrying out an oxidation reaction on the material I and O 2 -containing gas to obtain a adipic acid-containing product material II. The inventor of the present application surprisingly found that by pre-activating cyclohexane with ozone-containing gas and then oxidizing the pre-activated cyclohexane with O 2 -containing gas, the reaction rate is greatly increased, and the impurity content in the product material is greatly reduced, thereby improving the yield and selectivity of adipic acid. In some embodiments, the concentration of ozone in the ozone-containing gas is 0.1-8.0% by volume, such as 0.5%, 1.0%, 2.0%, 3.0%, 4.0%, 5.0%, 6.0%, 7.0%, 8.0% or any value therebetween. In some embodiments, the ozone in the ozone-containing gas is at a volume concentration of 0.5 to 5.0%. In some embodiments, the ozone-containing gas further comprises nitrogen. In some embodiments, the ozone mass to cyclohexane mass ratio in the ozone-containing gas is (0.005-0.1): 1, for example, 0.01:1, 0.02:1, 0.03:1, 0.04:1, 0.05:1, 0.06:1, 0.07:1, 0.08:1, 0.09:1, 0.1:1, or any value therebetween. In some embodiments, the temperature of the contacting is 10-80 ℃, e.g., 15 ℃,25 ℃, 35 ℃, 45 ℃,55 ℃, 65 ℃, 75 ℃, or any value therebetween. In some embodiments, the temperature of the contacting is 40-60 ℃. In some embodiments, the contacting is for a time of 10 to 120 minutes, for example, 20 minutes, 40 minutes, 60 minutes, 80 minutes, 100 minutes, 120 minutes, or any value therebetween. In some embodiments, the contacting is for a time of 10 to 60 minutes. In some embodiments, the oxidation reaction is performed in the presence of a catalyst and a solvent. In some embodiments, the solvent is selected from acetic acid. In some embodiments, the catalyst is selected from metal salt catalysts. In some embodiments, the metal element in the metal salt catalyst is selected from one or more of copper, manganese, or chromium. In some embodiments, the metal salt is an acetate o