TW202210459A - Preparation method of tetramethylpiperidol wherein the catalyst has high conversion rate and high selectivity to reduce the cost of subsequent purification and improve the economic benefit of the overall process - Google Patents

Abstract

A preparation method of tetramethylpiperidol comprises the following steps: in the presence of a catalyst, a solution containing tetramethylpiperidone is hydrogenated in a hydrogen atmosphere to obtain a solution containing tetramethylpiperidol, wherein, the catalyst includes a metallic nickel, and a silicon dioxide carrier carrying the metallic nickel. By using the catalyst in the invention, the hydrogenation reaction of tetramethylpiperidone can be carried out under the conditions of low reaction pressure and reaction temperature to form tetramethylpiperidol, and the catalyst has high conversion rate and high selectivity, thereby reducing the cost of subsequent purification and improving the economic benefit of the overall process.

Description

The preparation method of tetramethylpiperidol

The present invention relates to a preparation method of an alcohol compound, in particular to a preparation method of tetramethylpiperidinol.

Tetramethylpiperidol is a compound used to prepare products such as light stabilizers, bleaching agents, polymerization inhibitors, cross-linking agents, and pharmaceuticals. At present, the common preparation method of tetramethylpiperidol mainly converts tetramethylpiperidone into tetramethylpiperidol through hydroreduction treatment, and the hydroreduction treatment such as catalytic hydrogenation, chemical reduction, electrochemical reduction Among them, the catalytic hydrogenation method is the method mainly used in industry at present.

If the tetramethylpiperidol obtained by the hydrogenation reduction treatment contains other impurities or incompletely converted tetramethylpiperidone, it is difficult to convert the tetramethylpiperidol to the above-mentioned products using tetramethylpiperidol subsequently. The pyridone is separated, and the tetramethylpiperidone is prone to produce blood-red oxides after a long time, resulting in discoloration of the product. Therefore, the industry seeks to improve the conversion rate and selectivity of tetramethylpiperidinol in the catalytic hydrogenation method to fundamentally solve the above problems.

Chinese publication patent CN 103274991B discloses a method for continuous catalytic hydrogenation to produce tetramethylpiperidol. The reaction is carried out in the reactor group of hydrogen, and the pressure and temperature in the reactor group are controlled simultaneously to obtain tetramethylpiperidinol with a conversion rate of 100%. However, in order to obtain tetramethylpiperidol with high conversion rate, the hydrogenation reaction conditions must be controlled at a reaction temperature as high as 90°C to 100°C and a reaction pressure of 26 bar to 30 bar, and a cocatalyst needs to be added. to help the hydrogenation of tetramethylpiperidone.

Based on this, how to make the preparation of tetramethylpiperidinol simpler and energy-saving is a common goal of the industry at present.

Therefore, the purpose of the present invention is to provide a relatively energy-saving preparation method of tetramethylpiperidol.

Thus, the preparation method of tetramethylpiperidinol of the present invention comprises the following steps: (1) in the presence of a catalyst, the solution containing tetramethylpiperidone is hydrogenated in a hydrogen atmosphere to obtain a solution containing tetramethylpiperidinol, wherein the catalyst comprises metallic nickel, and a silicon dioxide carrier supporting the metallic nickel.

The effect of the present invention is: by using the catalyst including the metal nickel and the silica support to carry out the hydrogenation reaction, tetramethylpiperidone can be formed into tetramethylpiperidol at low reaction pressure and reaction temperature , and has high conversion rate and high selectivity, thereby reducing the cost of subsequent purification and improving the economic benefit of the overall process.

The preparation method of tetramethylpiperidol of the present invention comprises the following steps: (1) in the presence of a catalyst, hydrogenating the solution containing tetramethylpiperidone in a hydrogen atmosphere to obtain a solution containing tetramethylpiperidone solution of piperidinol.

Wherein, the catalyst includes metallic nickel and a silicon dioxide carrier supporting the metallic nickel. The content of the metallic nickel is not particularly limited, for example, but not limited to, based on the total amount of the catalyst being 100 wt %, the content of the metallic nickel ranges from 50 wt % to 80 wt %. The properties of the catalyst are not particularly limited. In some embodiments of the present invention, the catalyst has a specific surface area ranging from 40 m ² /g to 200 m ² /g and a pore volume ranging from 0.1 cm ³ /g to 0.5 cm ³ /g, and an average pore size ranging from 2 nm to 50 nm.

In some embodiments of the present invention, a catalyst precursor including nickel oxide and a silicon dioxide carrier supporting the nickel oxide is prepared first, and then the catalyst precursor is hydrogenated and reduced in a hydrogen atmosphere. The catalyst is then used to catalyze the hydrogenation reaction of the tetramethylpiperidone.

The tetramethylpiperidone-containing solution includes tetramethylpiperidone and a solvent. The content of the tetramethylpiperidone is not particularly limited, for example, but not limited to, based on the total amount of the solution containing the tetramethylpiperidone being 100 wt%, the content of the tetramethylpiperidone is in the range of 10 wt% % to 15 wt%. Preferably, the solvent is selected from alcohols. In some embodiments of the present invention, the alcohols are selected from methanol, ethanol, isopropanol or any combination thereof.

The pressure and temperature of the hydrogenation reaction do not need to be particularly limited, and can be flexibly adjusted according to the conventional process technology of the hydrogenation reaction of tetramethylpiperidone. It is worth mentioning that, by using the catalyst in the present invention, the reaction pressure range of the hydrogenation reaction can be controlled at 1 bar to 10 bar, and the reaction temperature range can be controlled at 60 ° C to 70 ° C, and the tetramethyl The conversion rate and selectivity of piperidinol are high.

The hydrogenation reaction can be carried out in any reactor known in the art for the preparation of tetramethylpiperidinol, such as but not limited to batch reactors, stirred tank reactors, trickle bed reactors, upflow packed reactors bed reactor or multi-tube reactor, etc.

In order to obtain higher purity tetramethylpiperidol, the preparation method of tetramethylpiperidol of the present invention also comprises a step (2) after this step (1), which is The solution was subjected to purification procedures to isolate tetramethylpiperidinol.

In this step (2), the purification procedure, for example, firstly subject the solution containing tetramethylpiperidol to concentration treatment to obtain a saturated solution containing tetramethylpiperidol, and then the solution containing tetramethylpiperidine The saturated alcohol solution was filtered to obtain tetramethylpiperidinol crystals.

The concentration treatment can be carried out in any separation device for solvent removal in the prior art, such as but not limited to a vacuum concentrator, an evaporator or a flash column and the like.

The present invention will be further described with respect to the following examples, but it should be understood that the examples are only used for illustration and should not be construed as a limitation of the implementation of the present invention.

Preparation Example 1: Catalyst A Precursor

Dissolve 46.5 g of nickel nitrate in 300 mL of deionized water and mix to form an aqueous nickel nitrate solution. Next, an alkaline aqueous solution is added to the nickel nitrate aqueous solution to adjust the pH value of the nickel nitrate aqueous solution to 9 to 11, wherein the alkaline aqueous solution is added with ammonia water, sodium carbonate, sodium hydroxide or any two of the above. Prepared in deionized water. After that, the nickel nitrate aqueous solution with a pH value of 9 to 11 was heated to 60 ° C to 90 ° C and fully stirred, and then 4.27 g of water glass (sodium silicate) was added, and the stirring was continued for 1 to 4 hours before filtering. , then the obtained filter cake is dried at 110 ° C after washing with water, then sieved after calcining at 800 ° C for 4 hours, to obtain a catalyst A precursor with an average particle size range of 20 mesh to 30 mesh . The catalyst A precursor includes nickel oxide and a silicon dioxide carrier supporting the nickel oxide, wherein the catalyst A precursor has a specific surface area of 94.3 m ² /g, a pore volume of 0.183 cm ³ /g and an average pore size is 5.7 nm.

Preparation Example 2: Catalyst B Precursor

Dissolve 46.5 g of nickel nitrate in 300 mL of deionized water and mix to form an aqueous nickel nitrate solution. Next, an alkaline aqueous solution is added to the nickel nitrate aqueous solution to adjust the pH value of the nickel nitrate aqueous solution to 9 to 11, wherein the alkaline aqueous solution is added with ammonia water, sodium carbonate, sodium hydroxide or any two of the above. Prepared in deionized water. After that, heat the nickel nitrate aqueous solution with a pH value of 9 to 11 to 60 ° C to 90 ° C and stir well, then add 1.22 g of water glass (sodium silicate), and continue to stir for 1 to 4 hours before filtering , then the obtained filter cake is dried at 110 ° C after washing with water, then sieved after calcining at 800 ° C for 4 hours, to obtain a catalyst B precursor with an average particle size range of 20 mesh to 30 mesh . The catalyst B precursor includes nickel oxide and a silicon dioxide carrier supporting the nickel oxide, wherein the catalyst B precursor has a specific surface area of 84 m ² /g, a pore volume of 0.174 cm ³ /g and an average pore size is 5.9 nm.

Comparative Preparation Example 1: Catalyst C Precursor

34.9 g of nickel nitrate and 7.69 g of aluminum nitrate were dissolved in 300 mL of deionized water and mixed to form a mixed solution. Next, an alkaline aqueous solution is added to the mixed solution to adjust the pH of the mixed solution to 9 to 11, wherein the alkaline aqueous solution is deionized by adding ammonia water, sodium carbonate, sodium hydroxide or any two of the above. Prepared in water. Afterwards, the mixed solution with a pH value of 9 to 11 is heated to 60° C. to 90° C. and fully stirred, and filtered after continuous stirring for 1 to 4 hours, and then the obtained filter cake is washed with water at 110° C. C is dried, then sieved after calcining at 800° C. for 4 hours to obtain a catalyst C precursor with an average particle size range of 20 mesh to 30 mesh. The catalyst C precursor includes nickel oxide and an aluminum oxide carrier supporting the nickel oxide, wherein the catalyst C precursor has a specific surface area of 85.3 m ² /g, a pore volume of 0.316 cm ³ /g and an average pore size is 10 nm.

Example 1

After 7 mL of catalyst A precursor was filled in a reactor, hydrogen was injected into the reactor at a flow rate of 0.7 L/hr, and the catalyst was reacted at 450° C. for 6 to 8 hours in a hydrogen atmosphere to make the catalyst The precursor A is hydrogenated and reduced to form a catalyst A, and the catalyst A includes metallic nickel and a silicon dioxide carrier supporting the metallic nickel. 10 wt% of tetramethylpiperidone was dissolved in a solvent (the kind is ethanol) to obtain a solution containing tetramethylpiperidone. After the temperature of the reactor and the catalyst A dropped, the solution containing tetramethylpiperidone was transported into the reactor at a flow rate of 0.081 mL/min through a feed pump, and the reaction pressure was 5 The condition that bar and reaction temperature are 60 ℃ carries out hydrogenation reaction, obtains the solution containing tetramethyl piperidinol.

The tetramethylpiperidinol-containing solution is subjected to a purification procedure comprising the following steps: introducing the tetramethylpiperidinol-containing solution into a separation device for concentration treatment, and removing the tetramethylpiperidinol-containing solution 70 wt% to 80 wt% of the solvent in the medium to obtain a saturated solution containing tetramethyl piperidinol, then, the saturated solution containing tetramethyl piperidinol is washed with toluene, and then filtered to obtain tetramethylpiperidinol base piperidinol crystals.

Examples 2 to 6 and Comparative Examples 1 to 2

Examples 2 to 6 and Comparative Examples 1 to 2 formed tetramethylpiperidinol crystals in the same preparation method as in Example 1, except that Examples 2 to 6 and Comparative Examples 1 to 1 were changed as shown in Table 1 below. 2 preparation conditions. Among them, Examples 3 to 6 used the catalyst B precursor of Preparation Example 2. Comparative Examples 1 to 2 used the catalyst C precursor of Comparative Preparation Example 1, and the catalyst C included metallic nickel and an aluminum oxide carrier supporting the metallic nickel.

[Evaluation item]

1. Specific surface area, pore volume and average pore size

A specific surface area analyzer (manufacturer Micromeritic; model TriStar 3000) was used to perform nitrogen adsorption and desorption experiments on catalyst precursors A, B, and C, respectively, to analyze the specific surface area, pore volume and average of the catalyst precursors. Aperture. It should be added that although the above measurements are the properties of the catalyst precursors, the specific surface area, pore volume and average pore size will hardly change after the catalyst precursors are reduced to catalysts. Therefore, It can be understood that the specific surface area, pore volume and average pore diameter of the catalyst precursor can be regarded as equivalent to the specific surface area, pore volume and average pore diameter of the catalyst.

2. Conversion rate and selection rate

The tetramethylpiperidinol-containing solution was analyzed for conversion and selectivity of tetramethylpiperidinol using a gas chromatograph (manufacturer Agilent; model 7890B). Wherein, the temperature of the injection port of this gas chromatograph is set to 270 ℃, and the detector is a flame ion detector (FID), and the temperature of the detector is set to 290 ℃.

3. Purity

The tetramethylpiperidinol crystals were dissolved in ethanol to form a solution to be tested, and the solution to be tested was analyzed by a gas chromatograph (manufacturer Agilent; model 7890B) to analyze the purity of the tetramethylpiperidinol crystals. Wherein, the temperature of the injection port of this gas chromatograph is set to 270 ℃, and the detector is a flame ion detector (FID), and the temperature of the detector is set to 290 ℃.

Table 1 Example Comparative example 1 2 3 4 5 6 1 2 catalyst type A A B B B B C C Metal nickel nickel nickel nickel nickel nickel nickel nickel carrier silica silica silica silica silica silica aluminum oxide aluminum oxide Tetramethylpiperidone (wt%) 10 10 10 10 10 10 10 10 Type of solvent Ethanol Ethanol Ethanol Ethanol methanol methanol Ethanol Ethanol Reaction pressure (bar) 5 10 5 10 5 10 5 10 Reaction temperature (°C) 60 70 60 60 70 60 70 60 Flow rate of solution containing tetramethylpiperidone (mL/min) 0.081 0.081 0.089 0.089 0.089 0.089 0.081 0.081 Hydrogen flow rate (L/hr) 0.7 0.7 0.8 0.8 0.8 0.8 0.7 0.7 Number of purification procedures 1 1 1 1 1 1 3 3 Conversion rates(%) 99.11 99.62 99.51 99.76 99.31 99.49 96.2 94.5 Selectivity (%) 99.34 99.45 99.28 99.32 99.25 99.35 92 87.7 purity(%) 99.58 99.81 99.79 99.86 99.75 99.79 98.2 97.7

Referring to Table 1, in Examples 1 to 6, the hydrogenation reaction is carried out by using catalyst A or catalyst B including metal nickel and silicon dioxide carrier, and then the hydrogenation reaction is carried out at a low reaction pressure and reaction temperature, which can make four The conversion rate and selectivity of methylpiperidol are over 99%, and the purity of the obtained tetramethylpiperidol crystals is over 99.5% after only one purification procedure.

Comparative Examples 1 and 2 use catalysts comprising metal nickel and aluminum oxide supports to carry out the hydrogenation reaction. At the same reaction pressure and reaction temperature as in Examples 1 to 6, the tetramethyl The conversion rate of piperidinol is only 96.2% and the selectivity is only 92%, and the purity of the obtained tetramethylpiperidinol crystals is only 98.2% even after three purification procedures.

It is worth mentioning that the tetramethylpiperidol obtained through the preparation conditions of Examples 1 to 6 of the present invention has a higher purity than the tetramethylpiperidinol obtained under the preparation conditions of Comparative Examples 1 and 2, And it can significantly improve the discoloration problem when tetramethylpiperidol is used in the preparation of light stabilizers, bleaching agents, polymerization inhibitors, cross-linking agents, medicines and other products.

To sum up, the preparation method of tetramethylpiperidol of the present invention uses a catalyst comprising metal nickel and a silica carrier to carry out the hydrogenation reaction, so that tetramethylpiperidine can be prepared under the conditions of low reaction pressure and reaction temperature. The ketone forms tetramethylpiperidinol, and the conversion rate and selectivity are over 99%, thereby reducing the cost of subsequent purification and improving the economic benefit of the overall process. In addition, the tetramethylpiperidinol obtained by the preparation method of tetramethylpiperidinol of the present invention has higher purity than commercially available commodities, and can effectively avoid product discoloration in the subsequent process, so it can indeed be achieve the purpose of the present invention.

However, the above are only examples of the present invention, and should not limit the scope of implementation of the present invention. Any simple equivalent changes and modifications made according to the scope of the patent application of the present invention and the contents of the patent specification are still included in the scope of the present invention. within the scope of the invention patent.

Claims (10)

A preparation method of tetramethylpiperidol, comprising the following steps: (1) in the presence of a catalyst, make the solution containing tetramethylpiperidone carry out hydrogenation reaction in hydrogen atmosphere, and obtain the solution containing tetramethylpiperidol, wherein, this catalyst comprises metallic nickel, and a silicon dioxide carrier supporting the metallic nickel. The preparation method of tetramethylpiperidol according to claim 1, wherein, in the step (1), the pressure range of the hydrogenation reaction is 1 bar to 10 bar. The preparation method of tetramethylpiperidol as claimed in claim 1, wherein, in this step (1), the temperature range of the hydrogenation reaction is 60°C to 70°C. The preparation method of tetramethylpiperidol as claimed in claim 1, wherein, in the step (1), based on the total amount of the catalyst being 100 wt%, the content range of the metallic nickel is 50 wt% to 80 wt%. The preparation method of tetramethylpiperidol according to claim 1, wherein, in the step (1), the specific surface area of the catalyst ranges from 40 m ² /g to 200 m ² /g. The method for preparing tetramethylpiperidol according to claim 1, wherein, in the step (1), the pore volume of the catalyst ranges from 0.1 cm ³ /g to 0.5 cm ³ /g. The preparation method of tetramethylpiperidol according to claim 1, wherein, in the step (1), the average pore diameter of the catalyst ranges from 2 nm to 50 nm. The preparation method of tetramethylpiperidol as claimed in claim 1, wherein, in the step (1), the solution containing tetramethylpiperidone comprises tetramethylpiperidone and a solvent, and the The total amount of the solution containing tetramethylpiperidone is 100 wt%, and the content of the tetramethylpiperidone ranges from 10 wt% to 15 wt%. The method for preparing tetramethylpiperidinol according to claim 8, wherein the solvent is selected from alcohols. The preparation method of tetramethylpiperidol as claimed in claim 1, further comprising a step (2) after the step (1), which is to perform a purification procedure on the solution containing tetramethylpiperidol to separate out of tetramethylpiperidinol.