阅读说明：本技术 一种3-戊醇脱氢制备3-戊酮的方法 (Method for preparing 3-pentanone by dehydrogenating 3-pentanol ) 是由 石康明 于 2019-08-28 设计创作，主要内容包括：本发明公开一种3-戊醇脱氢制备3-戊酮的方法,采用催化精馏反应工艺,配方量的3-戊醇、乙二醇和改性无定型Raney镍催化剂进行催化脱氢反应,控制反应温度为125～145℃,系统压力为0.1～0.5bar；乙二醇的加入质量以加入的3-戊醇质量为基准计为20～40％；改性无定型Raney镍催化剂的组成为：Al(53％)-Ni(44％)-Mo(3％),重量百分比,催化剂的3-戊醇负荷WWH为6.0～10.0hr<Sup>-1</Sup>；催化脱氢反应的产物以气相出料,气相反应产物通过精馏提纯,精馏设备的理论塔板数为65,回流比为2∶1～5∶1。本发明通过在脱氢反应液中加入高沸点溶剂乙二醇,使脱氢反应温度升高至125～145℃,脱氢反应速率加快,有效提高了催化剂活性和使用效率,且通过改变乙二醇的加入量可实现对脱氢反应温度的灵活调节,从而延长了催化剂的使用寿命。(The invention discloses a method for preparing 3-pentanone by dehydrogenating 3-pentanol, which comprises the steps of carrying out catalytic dehydrogenation reaction on 3-pentanol, ethylene glycol and a modified amorphous Raney nickel catalyst according to the formula amount by adopting a catalytic rectification reaction process, wherein the reaction temperature is controlled to be 125-145 ℃, and the system pressure is 0.1-0.5 bar; the adding mass of the ethylene glycol is 20-40% based on the mass of the added 3-pentanol; the modified amorphous Raney nickel catalyst comprises the following components: al (53%) -Ni (44%) -Mo (3%), wherein the WWH of the catalyst under the load of 3-pentanol is 6.0-10.0 hr ‑1 (ii) a Discharging the product of the catalytic dehydrogenation reaction in a gas phase, and rectifying and purifying the gas-phase reaction product, wherein the theoretical plate number of a rectifying device is 65, and the reflux ratio is 2: 1-5: 1. According to the invention, a high-boiling point solvent glycol is added into dehydrogenation reaction liquid to raise the dehydrogenation reaction temperature to 125-145 DEG CThe dehydrogenation reaction rate is accelerated, the activity and the service efficiency of the catalyst are effectively improved, and the flexible adjustment of the dehydrogenation reaction temperature can be realized by changing the addition of the ethylene glycol, so that the service life of the catalyst is prolonged.)

1. A method for preparing 3-pentanone by dehydrogenating 3-pentanol is characterized in that a catalytic dehydrogenation rectification reaction process is adopted, 3-pentanol, ethylene glycol and a modified amorphous Raney nickel catalyst in a formula amount are subjected to catalytic dehydrogenation reaction, the reaction temperature is controlled to be 125-145 ℃, and the system pressure is 0.1-0.5 bar; wherein:

the adding mass of the glycol is 20-40% based on the mass of the added 3-pentanol, and the glycol is added into the reaction system at one time;

the modified amorphous Raney nickel catalyst comprises the following components: al (53%) -Ni (44%) -Mo (3%), wherein the percentage of each element is weight percentage, and the WWH of 3-pentanol load of the catalyst is 6.0-10.0 hr^-1；

Discharging the product of the catalytic dehydrogenation reaction in a gas phase, rectifying and purifying the gas-phase reaction product to obtain a 3-pentanone product, wherein the theoretical plate number of the rectifying equipment is 65, and the reflux ratio is 2: 1-5: 1.

2. The method for preparing 3-pentanone through dehydrogenation of 3-pentanol according to claim 1, wherein the WWH of the catalytic dehydrogenation catalyst under load of 3-pentanol is 6.5-8.5 hr^-1。

3. The method for preparing 3-pentanone through dehydrogenation of 3-pentanol according to claim 1, wherein the reaction temperature is 126-140 ℃.

4. The method for preparing 3-pentanone through dehydrogenation of 3-pentanol according to claim 1, wherein the system pressure is 0.2-0.4 bar.

5. The method for preparing 3-pentanone through dehydrogenation of 3-pentanol according to claim 1, wherein the amount of the added glycol is 25-35% by mass based on the mass of the added 3-pentanol.

6. The method for preparing 3-pentanone through dehydrogenation of 3-pentanol according to claim 1, wherein the reflux ratio is 3: 1 to 4: 1.

Technical Field

The invention belongs to the technical field of fine chemical engineering, and relates to a method for preparing 3-pentanone by dehydrogenating 3-pentanol.

Background

3-pentanone is an important intermediate of fine chemical products, and is mainly used for preparing products such as pesticides, medicines and the like. 3-pentanone can be prepared from propionic acid through decarboxylation at high temperature, but the reaction is a process for reducing molecular weight and needs to be carried out at very high temperature, so the reaction conditions are harsh, and the production efficiency is not ideal. In addition, 2-pentene which is processed in a carbon five fraction which is a byproduct in the preparation of ethylene by petroleum cracking is taken as a raw material, 3-pentanol can be produced through hydration reaction, and then 3-pentanone is prepared through dehydrogenation of the 3-pentanol.

Chinese patent CN201410768423.8 describes a method for preparing 3-pentanone from 2-pentene. In the technical scheme, the 3-pentanol is directly prepared into the high-purity 3-pentanone through catalytic dehydrogenation and rectification reaction. The dehydrogenation reaction temperature is 113-118 ℃, the reaction pressure is normal pressure, and the WWH of 3-pentanol load of the catalyst is 2.5-5.5 hr^-1The dehydrogenation reaction adopts granular Raney nickel type metal alloy as a catalyst, and comprises the following components: Al-Ni-A; wherein A is one of Ce and Bi, and the weight ratio of each component is as follows: al, Ni and A are 1, 0.8-0.94 and 0.03-0.2 respectively. The particle size of the catalyst is generally 0.01 to 0.1 mm. And discharging the dehydrogenation reaction product in a gas phase, and directly feeding the gas phase reaction product into a rectifying tower with a theoretical plate of 50 to purify to obtain a high-purity 3-pentanone product, wherein the reflux ratio is 1: 1-10: 1.

As is well known, the reaction for preparing 3-pentanone by dehydrogenating 3-pentanol is an endothermic reaction, and increasing the reaction temperature can accelerate the dehydrogenation reaction rate and effectively improve the service efficiency of the catalyst. In the technical scheme, as the boiling points of the 3-pentanol and the 3-pentanone are 115 ℃ and 102 ℃ respectively, the dehydrogenation reaction temperature can only be between 113 ℃ and 118 ℃, although the requirements of the reaction and the rectification are met, the dehydrogenation reaction of the 3-pentanol can not be carried out at the temperature of more than 118 ℃, so that the dehydrogenation reaction rate and the conversion rate of the 3-pentanol can not be improved, and the screened temperature is 113 ℃ to 118 ℃ and is not an ideal temperature. This recognition was confirmed in the literature "preparation of cyclopentanone by catalytic dehydrogenation of cyclopentanol" (Fine chemical, 2004, 21 (5): 388-391). In this document, the dehydrogenation temperature has a large influence on the conversion of cyclopentanol, especially in the low temperature region, where the conversion of cyclopentanol is very low, and when the temperature exceeds 124 ℃, the conversion increases, but then increases slowly. Therefore, if the evaporation of cyclopentanone is not considered, the reaction temperature is preferably not lower than 124 ℃, but if the continuous preparation of cyclopentanone by reactive distillation is employed, the reaction temperature is increased to a temperature between the boiling points of cyclopentanone and cyclopentanol (130.6 to 140.85 ℃). Meanwhile, no phenomenon that cyclopentanone selectivity is reduced by increasing the temperature is found in the experiment.

Therefore, it is necessary to increase the reaction temperature for dehydrogenating 3-pentanol to produce 3-pentanone to increase the conversion rate thereof.

Disclosure of Invention

The first object of the present invention is to provide a method for preparing 3-pentanone by dehydrogenation of 3-pentanol, wherein the reaction temperature for preparing 3-pentanone by dehydrogenation of 3-pentanol is increased to increase the conversion rate thereof.

In order to achieve the purpose, the invention adopts the following technical scheme:

a method for preparing 3-pentanone by dehydrogenating 3-pentanol adopts a catalytic rectification reaction process, and 3-pentanol, glycol and a modified amorphous Raney nickel catalyst in a formula amount are subjected to catalytic dehydrogenation reaction, wherein the reaction temperature is controlled to be 125-145 ℃, and the system pressure is 0.1-0.5 bar; wherein:

the adding mass of the glycol is 20-40% based on the mass of the added 3-pentanol, and the glycol is added into the reaction system at one time;

the modified amorphous Raney nickel catalyst comprises the following components: al (53%) -Ni (44%) -Mo (3%), wherein the percentage of each element is weight percentage, and the WWH of 3-pentanol load of the catalyst is 6.0-10.0 hr^-1；

Discharging the product of the catalytic dehydrogenation reaction in a gas phase, rectifying and purifying the gas-phase reaction product to obtain a 3-pentanone product, wherein the theoretical plate number of the rectifying equipment is 65, and the reflux ratio is 2: 1-5: 1.

Preferably, the WWH of the catalyst for catalytic dehydrogenation reaction under the load of 3-pentanol is 6.5-8.5 hr^-1。

Preferably, the reaction temperature is 126-140 ℃.

Preferably, the system pressure is 0.2-0.4 bar.

Preferably, the addition amount of the ethylene glycol is 25-35% by mass of the added 3-pentanol.

Preferably, the reflux ratio of the rectifying tower is 3: 1-4: 1.

Preferably, the reaction temperature is controlled to be 126-140 ℃, and the system pressure is 0.2-0.4 bar; wherein: the adding mass of the glycol is 25-35% based on the mass of the added 3-pentanol, and the glycol is added into the reaction system at one time; the WWH of the catalyst under 3-pentanol load is 6.5-8.5 hr^-1(ii) a The theoretical plate number of the rectifying tower is 65, and the reflux ratio is 3: 1-4: 1.

The key point of the invention is that a high boiling point solvent ethylene glycol is used, the boiling point of the ethylene glycol is 197.3 ℃, which is far higher than 115 ℃ of 3-pentanol and 102 ℃ of 3-pentanone, after a proper amount of the ethylene glycol is added into dehydrogenation reaction liquid formed by the 3-pentanol and a catalyst, the dehydrogenation reaction temperature can be obviously improved, the ethylene glycol does not participate in the reaction, no negative influence is caused on the dehydrogenation of the 3-pentanol, and the boiling point of the ethylene glycol is high, which is basically not reduced along with the evaporation of the 3-pentanol/3-pentanone mixture, so the ethylene glycol only needs to be added at the beginning of the reaction. In addition, the selectivity of 3-pentanol dehydrogenation to 3-pentanone is not closely related to the temperature, and the dehydrogenation temperature is close to 100% in the range of 113-145 ℃, so the influence of the temperature on the reaction selectivity can be not considered.

It should be noted that, in the present invention, the Raney nickel type metal alloy catalyst can be prepared by a conventional method. Under the protection of nitrogen, powdered metal nickel, aluminum powder and molybdenum powder are mixed uniformly according to a certain proportion and then heated until all components are melted into solid solution. Cooling to room temperature, crushing and sieving the massive catalyst to reach required granularity, and packing.

In the invention, the granularity of the modified amorphous Raney nickel catalyst is generally 0.03-0.05 mm. The modified amorphous Raney nickel catalyst needs to be activated before use, and the activation of the catalyst can be carried out according to the known activation method of Raney nickel type metal alloy catalyst.

In the present invention, the above-mentioned catalytic dehydrogenation rectification reaction can be carried out using a conventional rectification column. Dehydrogenation reaction is carried out in a tower kettle, a catalyst and a 3-pentanol raw material are placed in the tower kettle, a slurry pump is used for circulating liquid materials containing the catalyst, the catalyst is uniformly distributed in tower kettle liquid, the restriction of mass transfer on the dehydrogenation reaction is eliminated, the dehydrogenation reaction rate is accelerated, gasified materials directly enter a rectifying tower for rectification and purification, a high-purity 3-pentanone product is obtained at the tower top, unreacted 3-pentanol directly flows back to the dehydrogenation reaction part from the rectifying part for continuous reaction, and hydrogen generated by dehydrogenation is directly discharged or recycled.

The catalytic dehydrogenation rectification reaction can also be carried out in a catalytic rectification device, and the catalytic rectification device comprises an upper part and a lower part, wherein the upper part is a rectification part, and the lower part is a reaction part. The reaction part is a liquid phase slurry bed reactor, and the rectification part can be a tray rectification column. The gasified reaction product is directly lifted to a rectifying column at the upper part for rectification, a high-purity 3-pentanone product is obtained at the column top of the rectifying column, and the unreacted 3-pentanol directly flows back to the dehydrogenation reaction part from the rectifying part for continuous reaction.

Compared with the prior art, the invention has the following beneficial technical effects:

for dehydrogenation reaction, the reaction temperature is increased, so that the dehydrogenation reaction rate is accelerated, and the use efficiency of the catalyst is effectively improved. According to the invention, the high-boiling point solvent glycol is added into the dehydrogenation reaction liquid to increase the dehydrogenation reaction temperature of the 3-pentanol, so that the dehydrogenation reaction temperature is increased from 113-118 ℃ to 125-145 ℃, the dehydrogenation reaction rate is accelerated, the activity and the use efficiency of the catalyst are effectively improved, and the flexible adjustment of the dehydrogenation reaction temperature can be realized by changing the addition of the glycol, thereby prolonging the service life of the catalyst.

Detailed Description

The present invention will be further described with reference to the following examples. It should be understood that the following examples are illustrative only and are not intended to limit the scope of the present invention.

In the following examples, the pressures are gauge pressures.

In the examples, the effect on the dehydrogenation reaction after the addition of ethylene glycol will be highlighted. The 3-pentanol conversion and the definition of WWH are:

the 3-pentanol concentration in the reaction liquid refers to the 3-pentanol concentration in GC.

Preparation of modified amorphous Raney nickel catalyst

Under the protection of nitrogen, powdered metal nickel, aluminum powder and molybdenum powder are mixed uniformly according to a certain proportion and then heated until all components are melted into solid solution. And cooling to room temperature, crushing and sieving the massive catalyst to obtain the granularity of 0.03-0.05 mm, and packaging to obtain the modified amorphous Raney nickel catalyst.

The catalyst needs to be activated before use, and the activation of the catalyst can be carried out according to the known activation method of Raney nickel type metal alloy catalyst.

The modified amorphous Raney nickel catalyst comprises the following components: al (53%) -Ni (44%) -Mo (3%), the percentages of the respective elemental compositions being in weight%.