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CN-122006695-A - Composite oxide catalyst, preparation method and application thereof

CN122006695ACN 122006695 ACN122006695 ACN 122006695ACN-122006695-A

Abstract

The invention discloses a composite oxide catalyst, a preparation method and application thereof, wherein the catalyst comprises M/Cr x O 3 -Al y O 3 , x+y=2, cr x O 3 -Al y O 3 is a main catalyst, M represents a metal auxiliary agent component, the preparation method comprises the steps of ball-milling, mixing and roasting Cr 2 O 3 and Al 2 O 3 to obtain a main catalyst, and reacting trifluoromethane with chloroform by utilizing two reactors connected in series under the action of the catalyst to obtain a reaction product containing difluoromethane and dichloromethane. The catalyst can show very high reactivity in the exchange reaction process of HFC-23 and CHCl 3 fluorine and chlorine without fluorination pretreatment, and can still meet the requirement of industrial application on stability under the condition of no addition of carbon deposit eliminating gas in the exchange reaction process of HFC-23 and CHCl 3 fluorine and chlorine.

Inventors

  • SHAO CHUNTAO
  • WANG ZHANGMING
  • ZHAO JINGPING
  • ZHANG HUINING

Assignees

  • 金华永和氟化工有限公司

Dates

Publication Date
20260512
Application Date
20260410

Claims (10)

  1. 1. The composite oxide catalyst is characterized by comprising M/Cr x O 3 -Al y O 3 , wherein x+y=2, cr x O 3 -Al y O 3 is a main catalyst, and is obtained by ball milling, mixing and roasting Cr 2 O 3 and Al 2 O 3 , wherein M represents a metal auxiliary component, and the addition amount is 0.1-10wt%.
  2. 2. The composite oxide catalyst according to claim 1, wherein the metal promoter component is selected from either one or both of metals W, mo, V, nb.
  3. 3. A method for preparing the composite oxide catalyst according to claim 1, comprising the steps of: Adding Al 2 O 3 nano powder and Cr 2 O 3 nano powder into deionized water, uniformly stirring, transferring into a ball mill, ball milling for a set time, and drying and roasting the ball-milled slurry to obtain a solid product; and 2, doping the metal auxiliary component into the solid product obtained in the step 1 by an impregnation method, and drying and roasting to obtain the final product of the composite oxide catalyst.
  4. 4. The method for preparing a composite oxide catalyst according to claim 3, wherein the particle size of the Al 2 O 3 nano powder and the Cr 2 O 3 nano powder in the step 1 is 20 to 200nm.
  5. 5. The method for preparing a composite oxide catalyst according to claim 3, wherein the mass ratio of the Al 2 O 3 nano powder to the Cr 2 O 3 nano powder in the step 1 is 1 (0.01-1).
  6. 6. The method for preparing a composite oxide catalyst according to claim 3, wherein the mass ratio of the total mass of the Al 2 O 3 nano powder and the Cr 2 O 3 nano powder to deionized water in the step 1 is (0.5-1): 1.
  7. 7. The method for preparing a composite oxide catalyst according to claim 3, wherein the ball milling time in the step 1 is 2-10 h, and the ball milling rotation speed is 100-500 r/min.
  8. 8. The method for preparing a composite oxide catalyst according to claim 3, wherein the calcination temperature in step 1 is 400-700 ℃, the calcination time is 5-15 hours, and the calcination atmosphere is air.
  9. 9. The use of the composite oxide catalyst according to claim 1 in a fluorine-chlorine exchange reaction, characterized in that CHCl 3 and HFC-23 are used as raw materials, and the composite oxide catalyst is used as a reaction catalyst, and HCFC-22 and HCFC-21 are obtained by conversion through the fluorine-chlorine exchange reaction.
  10. 10. The use of the composite oxide catalyst according to claim 9 in a fluorine-chlorine exchange reaction, wherein the fluorine-chlorine exchange reaction comprises the steps of: Under the action of the catalyst, reacting the trifluoro methane with chloroform by using two reactors connected in series to obtain a reaction product containing difluoro chloromethane and monofluoro dichloromethane, wherein the reaction temperature is 150-350 ℃; Rectifying and separating the reaction product containing difluoro chloromethane and monofluorodichloromethane at the outlet of the first reactor, and sending the raw materials of trifluoro chloromethane and chloroform into the second reactor for continuous reaction, wherein the difluoro chloromethane and monofluorodichloromethane separated at the outlet of the two reactors are recycled after being separated.

Description

Composite oxide catalyst, preparation method and application thereof Technical Field The invention belongs to the technical field of catalyst preparation, and particularly relates to a composite oxide catalyst, a preparation method and application thereof. Background Trifluoromethane (HFC-23, R23) is an unavoidable by-product of the industrial production of difluoromethane chloride (HCFC-22, R22), and its greenhouse potential is 14800 times that of CO 2, which is one of the typical strong greenhouse gases. HFC-23 is typically treated by high temperature incineration at 1200 ℃. The method has the advantages of large investment, large pollution, high energy consumption and easy corrosion of the decomposed product hydrogen fluoride. Although the use of HCFC-22 as a refrigerant is being accelerated, HCFC-22 used as a raw material for producing fluorocarbons such as tetrafluoroethylene has long been in existence, and thus by-produced trifluoromethane has long been continuously produced. Therefore, the recycling of HFC-23 is a treatment means for achieving both economical efficiency and environmental protection. The prior reported HFC-23 resource utilization methods are more. For example, patent US3009966A discloses a method for preparing tetrafluoroethylene and hexafluoropropylene by thermal cracking, patent CN104628514A discloses a method for preparing vinylidene fluoride by co-cracking with CH 4, and WO96/29296 discloses a method for forming macromolecular fluoroalkyl by co-cracking with fluoroalkyl, and the like. However, these methods are difficult to realize industrial application due to the severe reaction conditions, low product selectivity, short catalyst life and the like. While patents CN112979410a and CN112973685A disclose a method for producing HCFC-22 and HCFC-21 by the exchange of HFC-23 and CHCl 3 fluorochloros under the catalysis of lewis acid catalysts. The method has relatively mild reaction conditions and high product selectivity, so that the technology basically meets the requirement of industrialization. However, the service life of the catalyst is still short, so in order to improve the service life of the catalyst, gases such as oxygen, chlorine, hydrogen and the like which promote the elimination of carbon deposition are generally added in the reaction stage to improve the catalytic efficiency and stability of the catalyst. But this also results in the inevitable production of by-products such as carbon monoxide, carbon dioxide, monofluorotrichloromethane (R11), difluorodichloromethane (R12), etc. in the reaction. These byproducts and unreacted carbon-depleted gas have an influence on the separation and purification of the subsequent products, particularly, oxidizing substances such as oxygen, and even HCFC-22 raw materials containing a small amount of oxygen present a great risk in the process of producing TFE (tetrafluoroethylene) by pyrolysis, and even by-products such as oxygen, carbon monoxide, carbon dioxide and the like are removed by rectification means in the post-treatment of HCFC-22, additional separation costs are spent and product losses are incurred. In addition, the catalyst disclosed in the patent at the present stage needs to be activated by AHF before being used, so that the activation time is long, the cost is high, the energy consumption is high, and the risk is high. The conversion rate of HFC-23 is lower, the general single-pass conversion rate can not exceed 30%, and a large amount of HFC-23 and CHCl 3 need to be circularly operated, so that the problems of increased energy consumption, heavy equipment load, reduced process efficiency and the like are caused. Therefore, the development of a catalyst which can still meet the requirements of industrial application on conversion rate and stability under the condition of no addition of carbon deposit elimination gas in the exchange reaction process of HFC-23 and CHCl 3 has important significance. Disclosure of Invention Aiming at the defects of the prior art, the invention provides a composite oxide catalyst, a preparation method and application thereof, which can show very high reactivity in the exchange reaction process of HFC-23 and CHCl 3 and can still meet the requirement of industrial application on stability under the condition that no carbon deposit eliminating gas is added in the exchange reaction process of HFC-23 and CHCl 3. In order to solve the technical problems, the invention adopts the following technical scheme: First, a composite oxide catalyst having a composition of M/Cr xO3-AlyO3, wherein x+y=2, Wherein Cr xO3-AlyO3 is used as a main catalyst, is obtained by ball milling, mixing and roasting Cr 2O3 and Al 2O3, M represents a metal auxiliary component, and the addition amount is 0.1-10wt%. Preferably, the metal auxiliary component is selected from any one or two of metals W, mo, V, nb. In addition, a preparation method of the composite oxide catalyst is provided, which comprises the following steps: