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CN-121990866-A - Method for oxidative coupling of methane and method for improving conversion rate and selectivity of oxidative coupling reaction of methane

CN121990866ACN 121990866 ACN121990866 ACN 121990866ACN-121990866-A

Abstract

The invention relates to the technical field of methane oxidative coupling, and discloses a method for oxidative coupling of methane and a method for improving conversion rate and selectivity of oxidative coupling reaction of methane. The method comprises the steps of introducing raw gas into a reactor filled with a lanthanum-containing catalyst to perform methane oxidative coupling reaction, wherein the raw gas comprises methane, water, CO 2 and gas containing oxygen, and the molar concentration of the introduced CO 2 is more than 1mol percent based on the total molar of the raw gas. The method can reduce the hot spot temperature of the catalyst bed and prolong the service life of the catalyst. And meanwhile, the initial reactivity of the methane coupling reaction can be improved, and the initial conversion rate of methane and the initial selectivity of hydrocarbons with two or more carbon atoms are improved.

Inventors

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

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
20241104

Claims (10)

  1. 1. A method for oxidative coupling of methane is characterized by comprising the step of introducing raw gas into a reactor filled with a lanthanum-containing catalyst for oxidative coupling reaction of methane, wherein the raw gas comprises methane, water, CO 2 and gas containing oxygen, and the molar concentration of CO 2 is more than 1mol%, preferably 1-5mol%, based on the total mol of the raw gas.
  2. 2. The method according to claim 1, wherein the CO 2 is stopped when the difference between the molar concentration of CO 2 in the reactor and the amount of CO 2 fed in the feed gas is 0.01-5 mol%.
  3. 3. The method of claim 1, wherein the lanthanum containing catalyst comprises at least one of lanthanum oxide, lanthanum hydroxide, and lanthanum oxycarbonate.
  4. 4. The process according to claim 1, wherein the molar ratio of methane to water is 1:1-5, preferably 1:2-5.
  5. 5. The process of claim 1, wherein the water is introduced into the reactor in liquid form.
  6. 6. The method according to claim 1, wherein the molar ratio of methane to oxygen-containing gas in terms of oxygen is 2-10:1, preferably 2-8:1.
  7. 7. The process according to claim 1, wherein the reaction space velocity in terms of methane in the oxidative coupling reaction is 5000-200000ml/gh.
  8. 8. A process according to claim 1, wherein the temperature of the reaction is 500-750 ℃, preferably 500-700 ℃.
  9. 9. The method according to claim 1, wherein the reactor is filled with quartz wool at an upper end of the lanthanum-containing catalyst; more preferably, the filling height of the quartz wool is 1-5mm.
  10. 10. A method for improving the conversion rate and selectivity of methane oxidative coupling reaction is characterized by comprising the step of introducing raw gas into a reactor filled with a lanthanum-containing catalyst for methane oxidative coupling reaction, wherein the raw gas comprises methane, water, CO 2 and oxygen-containing gas, and the molar concentration of CO 2 is more than 1mol%, preferably 1-5mol%, based on the total mol of the raw gas.

Description

Method for oxidative coupling of methane and method for improving conversion rate and selectivity of oxidative coupling reaction of methane Technical Field The invention relates to the technical field of methane oxidative coupling, in particular to a method for methane oxidative coupling and a method for improving conversion rate and selectivity of methane oxidative coupling 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 1982 Keller and Bhasin reported paper, the technology has been the focus of attention in the fields of catalysis, chemical industry and petroleum and natural gas, oxidative coupling of methane is an exothermic reaction, the generated products are mainly ethylene, ethane and water, the technology has the characteristics of good atomic economy and environmental friendliness, and has become the targets of scientific research and competitive research of various large enterprises in the last forty years, Because the temperature of the oxidative coupling reaction of methane is higher, the catalyst bed layer can generate higher temperature rise in the reaction process, and meanwhile, the initial performance of the catalyst is poorer, and the catalyst can reach a stable state after a period of time. Therefore, in the industrialization of the oxidative coupling reaction of methane, the temperature of the catalyst bed is increased to cause unstable reaction, and the initial performance of the catalyst is poor to cause poor factory benefits. Disclosure of Invention The invention aims to solve the problems of high catalyst bed temperature and poor initial performance of a catalyst in the prior art, and provides a method for oxidative coupling of methane and a method for improving the conversion rate and selectivity of the oxidative coupling reaction of methane. In order to achieve the above object, the first aspect of the present invention provides a method for oxidative coupling of methane, comprising introducing a raw material gas comprising methane, water, CO 2 and an oxygen-containing gas into a reactor filled with a lanthanum-containing catalyst to perform oxidative coupling reaction of methane, wherein the molar concentration of CO 2 is 1mol% or more, preferably 1 to 5mol% based on the total molar amount of the raw material gas. In a second aspect, the invention provides a method for improving conversion rate and selectivity of methane oxidative coupling reaction, which comprises introducing feed gas into a reactor filled with a lanthanum-containing catalyst for methane oxidative coupling reaction, wherein the feed gas comprises methane, water, CO 2 and gas containing oxygen, and the molar concentration of CO 2 is more than 1mol%, preferably 1-5mol%, based on the total mol of the feed gas. Through the technical scheme, the invention has the following beneficial effects: The method can reduce the hot spot temperature of the catalyst bed and prolong the service life of the catalyst. And meanwhile, the initial reactivity of the methane coupling reaction can be improved, and the initial conversion rate of methane and the initial selectivity of hydrocarbons with two or more carbon atoms are improved. Preferably, the process of the present invention is also capable of increasing the conversion of methane and the selectivity to hydrocarbons of carbon two and above during stable operation. 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 ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein. According to a first aspect of the invention there is provided a process for the oxidative coupling of methane comprising introducing a feed gas comprising methane, water, CO 2 and an oxygen-containing gas to a reactor charged with a lanthanum-containing catalyst for the oxidative coupling of methane, the molar concentration of CO 2 being above 1mol%, preferably in the range 1 to 5mol%, based on the total moles of feed gas. The inventor of the invention discovers that when water and CO 2 are simultaneously introduced at the beginning of the oxidative coupling reaction of methane, the hot spot temperature of a catalyst bed layer can be reduced, the service life of the catalyst is prolonged, and the industrial scale-up is facilitated. Meanwhile, the initial reaction activity of the methane coupling reaction can be improved, the initial conversion rate of methane and the initial selectivity of hydrocarbons with two or more c