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CN-121991008-A - Method for preparing ethylene oxide by coupling methane oxidative coupling reaction and ethylene epoxidation reaction

CN121991008ACN 121991008 ACN121991008 ACN 121991008ACN-121991008-A

Abstract

The invention relates to the technical field of oxidative coupling of methane and epoxidation of ethylene, and discloses a method for preparing ethylene oxide by coupling the oxidative coupling reaction of methane and the epoxidation reaction of ethylene, which comprises the following steps of carrying out oxidative coupling reaction on methane in the presence of an oxidative coupling catalyst to obtain a first gas phase product containing ethylene, CO 2 and CO; (2) contacting the first gas-phase product with an oxidant to enable CO in the first gas-phase product to undergo an oxidation reaction to generate CO 2 , and then removing at least part of CO 2 to obtain a second gas-phase product, wherein the volume content ratio of carbon dioxide to ethylene in the second gas-phase product is 0.1-0.3:1, (3) contacting the second gas-phase product with a catalyst to enable ethylene in the second gas-phase product to undergo an epoxidation reaction. The invention not only improves the added value of the final product, but also saves the step of separating the products of the oxidative coupling reaction of methane, and greatly reduces the energy consumption and the cost of separation.

Inventors

  • WU JIEHUA
  • WANG XUE
  • DING CHENGZHE
  • BAI JIE
  • LI WEI

Assignees

  • 中国石油化工股份有限公司
  • 中石化(北京)化工研究院有限公司

Dates

Publication Date
20260508
Application Date
20241105

Claims (10)

  1. 1. A method for preparing ethylene oxide by coupling a methane oxidative coupling reaction and an ethylene epoxidation reaction, which is characterized by comprising the following steps: (1) In the presence of an oxidative coupling catalyst, carrying out oxidative coupling reaction on methane to obtain a first gas-phase product containing ethylene, CO 2 and CO; (2) The first gas-phase product is contacted with an oxidant, CO in the first gas-phase product is subjected to oxidation reaction to generate CO 2 , and at least part of CO 2 is removed to obtain a second gas-phase product, wherein the volume content ratio of carbon dioxide to ethylene in the second gas-phase product is 0.1-0.3:1; (3) Contacting the second gas phase product with a catalyst to cause epoxidation of ethylene in the second gas phase product.
  2. 2. The method according to claim 1, wherein in step (3), the catalyst is a supported catalyst, preferably the supported catalyst comprises Ag and a carrier, the Ag having a rod-like structure; more preferably, the rod-like structure has a length of 10-200nm, preferably 50-200nm, and a diameter of 2-10nm, preferably 2-8nm.
  3. 3. The process according to claim 2, wherein the Ag content is 5-30 wt%, preferably 13-25 wt%, based on the total weight of the supported catalyst; And/or the carrier in the supported catalyst is alumina.
  4. 4. The process according to claim 2, wherein the supported catalyst further comprises an alkaline earth metal promoter, preferably the alkaline earth metal promoter comprises at least one of Mg, ca, sr and Ba, more preferably the alkaline earth metal promoter is present in an amount of 0.001-0.05 wt%, preferably 0.003-0.04 wt%, based on the total weight of the supported catalyst.
  5. 5. The process of claim 1, wherein the conditions under which the epoxidation of ethylene occurs in step (3) comprise a temperature of 220 to 250℃and a pressure of 1 to 2.1MPa, and a space velocity in terms of ethylene of 7000 to 10000h -1 .
  6. 6. The process of claim 1 wherein step (3) further comprises mixing the second vapor phase product with an inhibitor and then contacting the mixture with a catalyst, wherein the inhibitor is dichloroethane and the volume ratio of inhibitor to ethylene is from 0.002 to 0.005:1.
  7. 7. The method of claim 1, wherein the oxidative coupling catalyst comprises at least one of NaWMn/SiO 2 、NaWMn/TiO 2 、NaWMn/BaTiO 3 , lanthanum oxide, lanthanum oxycarbonate, and lanthanum hydroxide; And/or the conditions of the oxidative coupling reaction comprise the temperature of 450-900 ℃, the molar ratio of methane to oxygen of 3-8:1 and the reaction space velocity of 10000-100000ml/gh calculated by methane.
  8. 8. The process of claim 1, wherein the first gaseous product has an ethylene content of 2-5 vol% and a CO content of 2-10 vol%; And/or the first gas phase product further comprises methane, ethane and CO 2 , wherein the content of methane in the first gas phase product is 50-90 vol%, the content of ethane is 2-10 vol%, and the content of CO 2 is 4-25 vol%; and/or, the step (1) further comprises the steps of cooling the product of the oxidative coupling reaction of methane to remove water; and/or, the first gas phase product also comprises oxygen, and the content of the oxygen is lower than 0.5 volume percent.
  9. 9. The method of claim 1, wherein the oxidizing agent is copper oxide; And/or the condition of the contact of the first gas-phase product and the oxidant comprises that the temperature is 200-500 ℃, and the molar ratio of carbon monoxide to the oxidant in the first gas-phase product is 1:1-1.2.
  10. 10. The process of claim 1, further comprising separating the ethylene oxide produced by the reaction in step (3) and returning unreacted ethylene to step (3); And/or the method further comprises separating the ethylene oxide generated by the reaction in the step (3), and returning unreacted methane to the step (1).

Description

Method for preparing ethylene oxide by coupling methane oxidative coupling reaction and ethylene epoxidation reaction Technical Field The invention relates to the technical field of methane oxidative coupling and ethylene epoxidation, in particular to a method for preparing ethylene oxide by coupling a methane oxidative coupling reaction and an ethylene epoxidation reaction. Background The oxidative coupling of methane to ethylene and ethane is one of the most challenging and focused research subjects in the catalytic field at present because of its academic significance and potential great economic value. Since the paper report of Keller and Bhasin in 1982, the technology has been the focus of attention in the fields of catalysis, chemical industry and petroleum and natural gas, the oxidative coupling of methane is an exothermic reaction, the produced products are mainly ethylene, ethane and water, and carbon monoxide and carbon dioxide produced by deep oxidation, the technology has the characteristics of good atomic economy and environmental friendliness, the technology has become the targets of scientific research and competitive research of various large enterprises in the last forty years, and the separation of ethylene, ethane and methane is usually carried out by adopting a physical method, so that the separation difficulty is high and the cost is high. Ethylene Oxide (EO) is one of the simplest cyclic ethers, which belongs to the class of heterocyclic compounds and is an important petrochemical. Ethylene oxide is a colorless transparent liquid at low temperature, ethylene oxide is a 2 nd generation chemical disinfectant appearing after formaldehyde and is also the most important member of the four low temperature sterilization technologies (low temperature plasma, low temperature formaldehyde vapor, ethylene oxide, glutaraldehyde) at present. Disclosure of Invention The invention aims to solve the problem of high separation cost of the oxidative coupling reaction product of methane in the prior art, organically combines the oxidative coupling reaction of methane with the preparation of ethylene oxide by ethylene epoxidation, reduces the separation process operation on one hand, reduces the separation cost of the oxidative coupling reaction product of methane, directly utilizes the oxidative coupling reaction product of methane to carry out the preparation of ethylene oxide by ethylene epoxidation on the other hand, and improves the added value of the product. The inventor of the present invention also found that when CO is removed from the reaction product of oxidative coupling of methane while controlling the concentration of CO 2 within a specific range, the progress of the ethylene epoxidation reaction can be promoted, and higher ethylene conversion and ethylene oxide selectivity can be obtained. In order to achieve the above object, a first aspect of the present invention provides a method for preparing ethylene oxide by coupling a methane oxidative coupling reaction with an ethylene epoxidation reaction, comprising the steps of: (1) In the presence of an oxidative coupling catalyst, carrying out oxidative coupling reaction on methane to obtain a first gas-phase product containing ethylene, CO 2 and CO; (2) The first gas-phase product is contacted with an oxidant, CO in the first gas-phase product is subjected to oxidation reaction to generate CO 2, and at least part of CO 2 is removed to obtain a second gas-phase product, wherein the volume content ratio of carbon dioxide to ethylene in the second gas-phase product is 0.1-0.3:1; (3) Contacting the second gas phase product with a catalyst to cause epoxidation of ethylene in the second gas phase product. Through the technical scheme, the following beneficial effects are achieved: According to the invention, the oxidation coupling reaction of methane and the oxidation reaction of ethylene are organically combined to prepare the ethylene oxide, so that the additional value of a final product is improved, the step of separating the products of the oxidation coupling reaction of methane is saved, and the energy consumption and the cost of separation are greatly reduced. The method can promote the ethylene epoxidation reaction to be carried out by removing CO in the methane oxidative coupling reaction product and controlling the concentration of CO 2 within a specific range, thereby obtaining higher ethylene conversion rate and ethylene oxide selectivity. Preferably, the silver-supported catalyst with a rod-shaped structure is adopted, so that the reaction temperature of ethylene epoxidation can be effectively reduced, and higher ethylene conversion rate and ethylene oxide selectivity can be obtained. Detailed Description The endpoints and any values of the ranges disclosed herein are not limited to the precise range or value, and are understood to encompass values approaching those ranges or values. For numerical ranges, one or more new numerical ran