Search

CN-122006713-A - Preparation method of copper-based catalyst for preparing ethylene glycol by hydrogenation of high-activity dimethyl oxalate

CN122006713ACN 122006713 ACN122006713 ACN 122006713ACN-122006713-A

Abstract

The invention discloses a preparation method of a copper-based catalyst for preparing ethylene glycol by hydrogenating high-activity dimethyl oxalate, which is used for solving the problems of low conversion rate and poor ethylene glycol selectivity of the existing copper catalyst in the reaction, discarding a traditional preparation route taking Cu 2+ as a precursor, pre-reducing Cu 2+ by adopting a reducing agent in the preparation process, taking the generated Cu + as a key precursor, improving the dispersity of copper species on the surface of a carrier by regulating the preparation process, optimizing the electron distribution of active component copper, improving the proportion of Cu + in the catalyst, and finally realizing the dual promotion of the hydrogenation activity of the catalyst and the ethylene glycol selectivity, thereby providing a high-efficiency catalyst scheme for the industrialized application of preparing ethylene glycol by hydrogenating dimethyl oxalate. The catalyst disclosed by the invention is simple to prepare and low in cost, and the obtained copper-based catalyst is high in selectivity and conversion rate when being used for catalyzing the hydrogenation of dimethyl oxalate to prepare ethylene glycol, and has commercial application and popularization values.

Inventors

  • WANG JIAN
  • ZHAO CONG
  • WANG LI
  • REN XU
  • An Xiangtong
  • ZHANG HAN
  • CAO CHENGLONG
  • Chao zhe
  • CHENG JIE

Assignees

  • 西安凯立新材料股份有限公司

Dates

Publication Date
20260512
Application Date
20260116

Claims (8)

  1. 1. A preparation method of a copper-based catalyst for preparing ethylene glycol by hydrogenation of high-activity dimethyl oxalate is characterized by comprising the following steps of: step 1, mixing copper salt and ammonia water, and dissolving the mixture in a water bath at a temperature of between 30 and 50 ℃ to form a stable Cu 2+ complexing precursor solution; Step 2, adding a reducing agent into the Cu 2+ complexing precursor solution in a nitrogen flow atmosphere, and stirring for 30-90 minutes at room temperature to obtain a Cu + complexing precursor solution, wherein the reducing agent is one or more selected from hydroxylamine hydrochloride, hydrazine, glucose, sodium thiosulfate and the like; step 3, preparing copper-silicon precipitate by adopting an ammonia distillation method or preparing a copper-silicon compound by directly dipping a Cu + complexing precursor solution into a silicon dioxide carrier by adopting a dipping method in a nitrogen flow atmosphere; And 4, drying copper-silicon precipitate or copper-silicon compound in vacuum at 60-80 ℃, cooling to room temperature, roasting at 350-500 ℃ in a nitrogen atmosphere, and reducing at 180-300 ℃ in a mixed atmosphere of hydrogen with a hydrogen volume fraction of 2-8% to obtain a copper-based catalyst, wherein the copper loading amount in the catalyst is 5-35%.
  2. 2. The preparation method of the copper-based catalyst for preparing ethylene glycol by hydrogenating high-activity dimethyl oxalate, which is disclosed in claim 1, is characterized in that in step 1, the mass ratio of copper salt to ammonia water is 1:1-3:1.
  3. 3. The preparation method of the copper-based catalyst for preparing ethylene glycol by hydrogenating high-activity dimethyl oxalate according to claim 1 or 2, wherein in the step 1, the copper salt is any one of copper nitrate, copper chloride and copper acetate.
  4. 4. The preparation method of the copper-based catalyst for preparing ethylene glycol by hydrogenating high-activity dimethyl oxalate, which is disclosed in claim 1, is characterized in that in the step 2, the molar ratio of the reducing agent to copper salt is 1:3-2:1.
  5. 5. The method for preparing the copper-based catalyst for preparing ethylene glycol by hydrogenating dimethyl oxalate with high activity according to claim 1, wherein in the step 3, the method for preparing the copper-silicon precipitate by adopting the ammonia distillation method is characterized in that after Cu + complexing precursor solution and silica sol are uniformly stirred in a nitrogen flow atmosphere, ammonia distillation is carried out at 90-100 ℃, heating is stopped when the pH is reduced to below 7, and after the temperature is reduced to room temperature, washing and filtering are carried out by using cold water, so that the copper-silicon precipitate is obtained.
  6. 6. The preparation method of the copper-based catalyst for preparing ethylene glycol by hydrogenating dimethyl oxalate with high activity, which is disclosed in claim 1, is characterized in that in step 4, copper silicon is precipitated at 60-80 ℃ and dried in vacuum, cooled to room temperature, roasted at 350-500 ℃ for 3-10 hours in nitrogen atmosphere, and then reduced at 180-300 ℃ for 8-20 hours in a mixed atmosphere of hydrogen with a volume fraction of 2% -8% of hydrogen and nitrogen.
  7. 7. The preparation method of the copper-based catalyst for preparing ethylene glycol by hydrogenating dimethyl oxalate with high activity, which is disclosed in claim 1, is characterized in that in step 4, copper silicon is precipitated at 80 ℃ and dried in vacuum, then cooled to room temperature, roasted at 400-450 ℃ for 5-8 hours in nitrogen atmosphere, and then reduced at 220-250 ℃ for 10-12 hours in mixed atmosphere of hydrogen with the volume fraction of hydrogen of 5% -6%.
  8. 8. The preparation method of the copper-based catalyst for preparing ethylene glycol by hydrogenating high-activity dimethyl oxalate, which is disclosed in claim 1, is characterized in that the copper loading amount in the catalyst is 15% -25%.

Description

Preparation method of copper-based catalyst for preparing ethylene glycol by hydrogenation of high-activity dimethyl oxalate Technical Field The invention belongs to the technical field of catalyst preparation, and particularly relates to a preparation method of a copper-based catalyst for preparing ethylene glycol by hydrogenation of high-activity dimethyl oxalate. Background Ethylene glycol is a key large-scale chemical raw material in the fields of polyester, antifreezing agent and the like, and the market demand is continuously growing. The traditional petroleum route for preparing ethylene glycol is constrained by resources and environmental protection, and a dimethyl oxalate (DMO) hydrogenation method is a non-petroleum route technology, and the core depends on a copper-based catalyst. The current main stream copper-based catalyst in industry and laboratory uses Cu 2+ compound as precursor, on one hand, cu 2+ is easy to agglomerate in roasting reduction process, copper species dispersity is low, effective active sites are insufficient, so that dimethyl oxalate hydrogenation activity is poor, conversion rate is low, on the other hand, the key active sites Cu + in the reduced catalyst are usually lower than 40%, cu 0 is too high, and side reactions such as excessive hydrogenation of ester groups, hydrolysis and decomposition are easy to be caused, so that glycol selectivity is low. In addition, the stability of the valence state of Cu + is poor, the active site is easy to run off, the catalytic performance is further restricted, and the development of a high-efficiency catalyst preparation method capable of synchronously improving the activity and the selectivity is needed. The Cu/SiO 2 catalyst adopted by the traditional ammonia distillation method is simple to prepare, but copper species are easy to agglomerate in the roasting reduction process, the proportion of reduced Cu + is small, excessive Cu 0 causes side reactions such as excessive hydrogenation and the like, and the selectivity and stability are poor. Li Zheng et al (Hydrogenation of dimethyl oxalate to ethanol over Mo-supported Cu/SiO 2 catalyst) prepares MoCu/SiO 2 catalyst by molybdenum doping, but the enhanced surface acidity leads to glycol dehydroxylation to generate ethanol, the selectivity is insufficient, xinlei Zheng and other （Lanthanum Oxide-Modified Cu/SiO2as a High-Performance Catalyst for Chemoselective Hydrogenation of Dimethyl Oxalate to Ethylene Glycol） additives are doped in the catalyst, the lanthanum-doped catalyst is sensitive to the dosage of the additives, copper grains are easy to sinter at high temperature, and long-period stable operation is difficult. In the technical aspect of a carrier with a special structure, the nano tube assembled hollow sphere catalyst disclosed in Tianjin university patent CN109248682A has higher glycol yield under the condition of low hydrogen ester ratio, but the catalyst preparation process is complex, the problem of nonuniform structure is easy to occur in large-scale production, and the gas-phase white carbon black supported catalyst has the defects of more byproducts and easy loss of active sites. Therefore, the prior art has the problems of difficulty in combining catalytic activity, selectivity and long-period stability, and high industrialization cost, and development of an efficient catalyst preparation method is needed. Disclosure of Invention In order to solve the problems of low raw material conversion rate and low ethylene glycol selectivity of a copper catalyst in the process of preparing ethylene glycol by hydrogenating dimethyl oxalate, the invention provides a preparation method of a copper-based catalyst, which is different from the traditional method of using Cu 2+ as a preparation precursor, adopts a reducing agent to prereduce a Cu 2+ copper source used in the traditional preparation method, uses the generated Cu + as a key precursor, improves the dispersity of copper on a carrier, combines inert atmosphere roasting and a mild reduction process, reduces aggregation of copper species in the preparation process, regulates and controls the electron valence distribution of copper, and improves the occupation ratio of Cu + in the catalyst, thereby improving the hydrogenation activity and the ethylene glycol selectivity of the catalyst. The preparation method of the copper-based catalyst provided by the invention comprises the following steps: And step 1, mixing copper salt and ammonia water, and dissolving the mixture in a water bath at a temperature of between 30 and 50 ℃ to form a stable Cu 2+ complexing precursor solution. The ammonia water is used as a complexing agent and has moderate coordination capacity with Cu +, and can be completely decomposed in the subsequent roasting process without residual impurities. And 2, adding a reducing agent to the Cu 2+ complexing precursor solution in a nitrogen flow atmosphere, wherein the reducing agent is selected from any one or