阅读说明：本技术 一种γ-氧化铝改性催化剂、其制备方法及在合成2,5-二氢呋喃中的应用 (Gamma-alumina modified catalyst, preparation method thereof and application thereof in synthesizing 2, 5-dihydrofuran ) 是由 王海英 戴耀 唐超 李殿虎 王荣良 王延波 于 2020-06-18 设计创作，主要内容包括：本发明公开了一种γ-氧化铝改性催化剂、其制备方法及其在合成2,5-二氢呋喃中的应用,属于催化剂制备及有机合成领域。本发明所述催化剂以γ-氧化铝为载体,经过三氯化铁及氯化钾改性,得到γ-氧化铝改性催化剂。将其装填至管式反应器中,经过氢气活化后,在加热状态下连续通入1,4-丁烯二醇,在反应管末端可以连续获得2,5-二氢呋喃。这种改性γ-氧化铝催化剂用于1,4-丁烯二醇环合制备2,5-二氢呋喃效率高,稳定好,可以长时间连续使用的优点,具有进一步放大生产的潜力。(The invention discloses a gamma-alumina modified catalyst, a preparation method thereof and application thereof in synthesizing 2, 5-dihydrofuran, belonging to the field of catalyst preparation and organic synthesis. The catalyst takes gamma-alumina as a carrier, and is modified by ferric trichloride and potassium chloride to obtain the gamma-alumina modified catalyst. Filling the mixture into a tubular reactor, activating by hydrogen, and continuously introducing 1, 4-butylene glycol under a heating state to continuously obtain 2, 5-dihydrofuran at the tail end of the reaction tube. The modified gamma-alumina catalyst is used for preparing 2, 5-dihydrofuran by cyclization of 1, 4-butylene glycol, has the advantages of high efficiency and good stability, can be continuously used for a long time, and has the potential of further amplified production.)

1. A preparation method of a gamma-alumina modified catalyst is characterized by comprising the following steps: the gamma-alumina is used as a carrier, an aqueous solution prepared from ferric trichloride hexahydrate and potassium chloride is added, and the modified gamma-alumina catalyst is obtained by soaking, filtering, cleaning, high-temperature treatment and nitrogen flow protection and cooling in a heating state.

2. The process according to claim 1, whereinCharacterized in that: the effective content of the gamma-alumina is more than 99.9 percent, and the specific surface area is 100-²G, the diameter of the spherical particles is 3-4 mm.

3. The method of claim 1, wherein: the total mass concentration of the aqueous solution prepared from the ferric trichloride hexahydrate and the potassium chloride is 5-10%; the molar ratio of the ferric trichloride to the potassium chloride is 1.0: 1.0-2.0.

4. The method of claim 1, wherein: the gamma-alumina is soaked in an aqueous solution prepared from ferric trichloride hexahydrate and potassium chloride at the temperature of 40-50 ℃.

5. The method of claim 1, wherein: the high-temperature treatment is heating for 1.5-2.0h at 400-500 ℃.

6. A gamma-alumina catalyst prepared according to the process of claim 1.

7. Use of a gamma-alumina catalyst according to claim 6 for the synthesis of 2, 5-dihydrofuran, wherein: the modified gamma-alumina catalyst is filled into a tubular reactor, hydrogen is introduced for activation in a heating state, then nitrogen is replaced, the temperature of a reaction tube is further increased, and then 1, 4-butylene glycol is continuously introduced to continuously obtain 2, 5-dihydrofuran at the tail end of the reaction tube.

8. Use according to claim 6, characterized in that: introducing hydrogen into the tubular reactor, and controlling the space velocity at 10.0-20.0h^-1The activation temperature is 50-60 ℃, and the activation time is 2-3 h.

9. Use according to claim 6, characterized in that: the tubular reactor is switched to nitrogen, and the space velocity is controlled to be 10.0-20.0h^-1Keeping 1.0-2.0h to completely replace the catalyst and the residual hydrogen in the reaction tube, and then further heating the reaction tube to the temperature220-270℃。

10. Use according to claim 9, characterized in that: after the temperature of the reaction tube is raised to 220-270 ℃, 1, 4-butylene glycol is continuously introduced, and the space velocity is controlled to be 15-20h^-1And collecting the generated 2, 5-dihydrofuran crude product at the tail end of the reaction tube.

Technical Field

The invention belongs to the field of catalyst preparation and organic synthesis, and particularly relates to a gamma-alumina modified catalyst, a preparation method thereof and application thereof in synthesizing 2, 5-dihydrofuran.

Background

2, 5-dihydrofuran is an important pesticide and an important intermediate of medicines, and is typically applied to the synthesis of 3-aminomethyl tetrahydrofuran and further the synthesis of dinotefuran (see: chemical reagents, 2018, 40 and 132). Dinotefuran is a low-toxicity and high-efficiency spectrum pesticide, can be used for preventing and treating diseases and insect pests of rice, vegetables and melons and fruits, and has a good market development prospect.

At present, the reported method for synthesizing 2, 5-dihydrofuran mainly takes 1, 4-butylene glycol as a raw material to generate cyclization dehydration reaction under the promotion of a catalyst to obtain a target product. Heterogeneous catalysts, such as alumina, molecular sieves, acidic macroporous resins, phosphotungstic heteropoly acids, etc., are currently most studied (see: CN 106866588). In addition, the 1, 4-butylene glycol and the 2,5 dihydrofuran product contain double bonds, and a conventional kettle type batch or semi-continuous reaction is adopted, so that partial raw materials and products are inevitably subjected to polymerization reaction to cause yield loss (see: CN 10639372), and therefore, the tubular reactor is also concerned in recent years for carrying out the 1, 4-butylene glycol cyclization reaction (see: CN110407776, US2011190516, CN 106496164).

Because the continuous reaction device usually has large one-time investment and the conversion efficiency of the raw materials filled with the catalyst is not high at present, the weight hourly space velocity is less than 10h^-1Greatly limiting the prospect of further industrialized production. Therefore, there is a need to develop more efficient catalysts for tubular reactions.

Disclosure of Invention

Aiming at the defects of the method, the invention provides a preparation method of a gamma-alumina modified catalyst, the catalyst prepared by the method and the application of the catalyst in the aspect of synthesizing 2, 5-dihydrofuran. Filling the mixture into a tubular reactor, activating by hydrogen, and continuously introducing 1, 4-butylene glycol under a heating state to continuously obtain 2, 5-dihydrofuran at the tail end of the reaction tube. The modified gamma-alumina catalyst is used for preparing 2, 5-dihydrofuran by cyclization of 1, 4-butylene glycol, has the advantages of high efficiency and good stability, can be continuously used for a long time, and has the potential of further amplified production.

The technical scheme of the invention is as follows:

the first aspect of the invention is to protect a preparation method of a gamma-alumina modified catalyst, and the specific technical scheme is as follows: the gamma-alumina is used as a carrier, an aqueous solution prepared from ferric trichloride hexahydrate and potassium chloride is added, and the modified gamma-alumina catalyst is obtained by soaking, filtering, cleaning, high-temperature treatment and nitrogen flow protection and cooling in a heating state.

In the above technical solution, further, in the method for preparing the catalyst, the effective content of gamma-alumina is more than 99.9%, and the specific surface area is 100-²G, the diameter of the spherical particles is 3-4 mm.

In the above technical solution, further, in the method for preparing the catalyst, the mass concentration of the aqueous solution prepared from ferric trichloride hexahydrate and potassium chloride is 5-10%; preferably, the molar ratio of the ferric trichloride to the potassium chloride is 1.0: 1.0-2.0.

In the technical scheme, further, in the method for preparing the catalyst, the gamma-alumina is soaked in an aqueous solution prepared from ferric trichloride hexahydrate and potassium chloride for 5-10 hours; preferably, the soaking temperature is 40-50 ℃; preferably, after the filtration, washing with gamma-alumina 2.0 to 3.0 times by mass of water is used.

In the above technical solution, further, in the method for preparing the catalyst, the γ -alumina after washing with water is heated at 400-.

A second aspect of the present invention is to protect the catalyst obtained by the above-described production method.

The third aspect of the invention is to protect the use of the catalyst obtained by the above preparation method for the synthesis of 2, 5-dihydrofuran.

For the above-mentioned application, further, the catalyst is filled in a tubular reactor, activated by introducing hydrogen in a heated state, then replaced with nitrogen, the temperature of the reaction tube is further increased, and then 1, 4-butenediol is continuously introduced to continuously obtain 2, 5-dihydrofuran at the end of the reaction tube. The reaction equation is:

for the application, further, the method for synthesizing 2, 5-dihydrofuran comprises the steps of filling the modified gamma-alumina catalyst into a tubular reactor, introducing hydrogen and controlling the space velocity to be 10.0-20.0h^-1The activation temperature is 50-60 ℃, and the activation time is 2-3 h.

For the above applications, further, the method for synthesizing 2, 5-dihydrofuran, activated gamma-alumina catalyst, is switched to nitrogen gas space velocity controlled at 10.0-20.0h^-1Keeping 1.0-2.0h to completely replace the residual hydrogen in the catalyst and the reaction tube, and then further heating the reaction tube to 220-270 ℃.

For the above applications, further, the method for synthesizing 2, 5-dihydrofuran comprises the steps of heating the reaction tube to 220-270 ℃, and then continuously introducing 1, 4-butylene glycol, wherein the space velocity is controlled to be 15-20h^-1And collecting the generated 2, 5-dihydrofuran crude product at the tail end of the reaction tube.

The invention has the following advantages:

1. the catalyst carrier is cheap and easy to obtain, the preparation process is simple, and after the active component is soaked in the carrier, the carrier is filtered, washed and heated at high temperature without special process operation.

2. The catalyst prepared by the method has heavy feed endThe space velocity reaches 15h^-1The product yield is more than 98 percent, the continuous operation is carried out for 40 hours, the yield is not obviously reduced, and the method has the potential of further enlarging production.

Detailed Description

The following non-limiting examples are presented to enable those of ordinary skill in the art to more fully understand the present invention and are not intended to limit the invention in any way.