Continuous reaction process for producing diacetone alcohol

Abstract

The invention discloses a continuous reaction process for producing diacetone alcohol, and relates to the technical field of chemical synthesis. The method comprises the following steps: step 1, condensation reaction: adding a composite catalyst into a reactor, then injecting acetone into the reactor through a feeding pipe, reacting and cooling to obtain a reaction mixture; step 2, primary rectification: transferring the reaction mixture into a rectification device, carrying out primary rectification, and collecting fractions of diacetone alcohol; 3, secondary rectification: carrying out secondary rectification on the diacetone alcohol fraction collected in the step 2, and collecting a diacetone alcohol primary product; and 4, tertiary rectification: carrying out tertiary rectification on the diacetone alcohol primary product collected in the step 3 to obtain diacetone alcohol. The method has the beneficial effects that the diacetone alcohol is prepared through an efficient continuous reaction process; moreover, through an effective modification process, the performance of the catalyst is improved, and the service life of the catalyst is also prolonged while the conversion rate of diacetone alcohol is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical synthesis, and particularly to a continuous reaction process for producing diacetone alcohol. Background Art

[0002] Diacetone Alcohol (DAA) is an important organic solvent and chemical intermediate, widely used in fields such as coatings, inks, adhesives, and pharmaceuticals. Traditional methods for producing diacetone alcohol usually employ batch reaction processes, involving multiple steps of reactions and complex separation processes, resulting in high energy consumption, low efficiency, and the possible generation of a large amount of by-products. To solve these problems, the development of efficient continuous reaction processes has become the focus of research.

[0003] In continuous reaction processes, the selection and optimization of catalysts are crucial. Commonly used catalysts include acid catalysts and base catalysts, among which acid catalysts can effectively promote the hydroxylation reaction of acetone to produce diacetone alcohol. Currently, due to the need for the diacetone alcohol reaction process to be carried out under low-temperature conditions, most catalysts have low activity; and some catalysts may not be able to effectively distinguish between the desired reaction path and the side reaction path, resulting in the large generation of by-products (isopropylidene acetone); at the same time, some catalysts cannot be recycled, and the product solution requires neutralization, has a slow reaction rate, generates a large amount of wastewater, and requires the recovery of salts, etc.

[0004] Therefore, to solve the above problems, the present invention provides a continuous reaction process for producing diacetone alcohol. Summary of the Invention

[0005] The purpose of the present invention is to provide a continuous reaction process for producing diacetone alcohol to solve the problems presented in the prior art.

[0006] To achieve the above purpose, the present invention provides the following technical solutions:

[0007] A continuous reaction process for producing diacetone alcohol, comprising the following steps:

[0008] Step 1: Condensation reaction: Load a composite catalyst into a reactor, and then inject acetone into it through a feeding pipe, react at 0 - 10°C for 4 - 6 hours, and cool to obtain a reaction mixture;

[0009] Step 2: First rectification: Transfer the reaction mixture to a rectification device and perform the first rectification at 90 - 95°C to collect the fraction of diacetone alcohol;

[0010] Step 3: Second rectification: Rectify the fraction of diacetone alcohol collected in Step 2 at 90 - 100°C and collect the crude product of diacetone alcohol;

[0011] Step 4: Three - stage rectification: Rectify the crude diacetone alcohol collected in Step 3 three times at 98 - 100 °C to obtain diacetone alcohol.

[0012] More optimally: The composite catalyst comprises the following components: by weight, 10 - 12 parts of a modified catalyst and 2 - 3 parts of modified zeolite.

[0013] More optimally: The preparation process of the modified catalyst is as follows:

[0014] S1: Put alumina and melamine into a chemical vapor deposition device, and then calcine in a muffle furnace to obtain modified alumina.

[0015] S2: (1) Disperse the modified alumina in ethanol and perform ultrasonic treatment to form suspension A; (2) Mix suspension A with an ethanol solution of cobalt(II) nitrate hexahydrate, perform ultrasonic treatment, centrifuge, and then add it to an ethanol solution of 2 - methylimidazole, perform ultrasonic treatment again, centrifuge, wash, and dry to obtain a preliminary catalyst.

[0016] S3: Add the preliminary catalyst to an ethanol solution of 2 - methylimidazole, perform ultrasonic treatment, add an ethanol solution of cobalt(II) nitrate hexahydrate, stir for 3 - 4 h, then centrifuge to separate the solid product, wash, and dry to obtain the modified catalyst.

[0017] In the scheme, first, a chemical vapor deposition method is used to load graphitic carbon nitride (with melamine as the precursor) on the surface of alumina to obtain modified alumina. Its abundant N - coordination sites can become ideal coordination sites for stably accommodating metal cations. Therefore, using the modified alumina as a carrier, Co ions are fixed on its surface by an ultrasonic - assisted method, and then 2 - methylimidazole is introduced as a connecting ligand to initially form a metal framework. Subsequently, through re - growth, the modified catalyst is obtained.

[0018] More optimally, the process parameters of the calcination are: temperature 550 - 600 °C, heating rate 5 - 8 °C / min, and time 8 - 10 h.

[0019] More optimally: The modified alumina raw material comprises the following components: by weight, 10 - 12 parts of melamine and 25 - 20 parts of alumina; the preliminary catalyst comprises the following components: by weight, 10 - 12 parts of suspension A, 6 - 8 parts of an ethanol solution of cobalt(II) nitrate hexahydrate, and 3 - 4 parts of an ethanol solution of 2 - methylimidazole; the modified catalyst comprises the following components: by weight, 10 - 12 parts of the preliminary catalyst, 3 - 4 parts of an ethanol solution of 2 - methylimidazole, and 5 - 8 parts of an ethanol solution of cobalt(II) nitrate hexahydrate.

[0020] More preferably: the mass fraction of the modified alumina in suspension A is 20 - 30 wt%; in the cobalt (II) nitrate hexahydrate ethanol solution, the mass fraction of cobalt (II) nitrate hexahydrate is 10 - 12 wt%; in the 2-methylimidazole ethanol solution, the mass fraction of 2-methylimidazole is 8 - 10 wt%.

[0021] More preferably: the preparation process of the modified zeolite is as follows: mix N,N,N-trimethyl-1-ammonium adamantane hydroxide with deionized water, add hexamethylenediamine and stir, then add fumed silica, stir for 12 - 15 h, then transfer to an autoclave, heat at 150 - 180 °C for 5 - 6 days, wash, dry, and calcine to obtain the modified zeolite.

[0022] In the scheme, through the hydrothermal synthesis method, a large number of silanol groups are formed on the surface of the zeolite. At the same time, its thin-layered structure and large external surface area enable it to effectively play a role in the catalytic process.

[0023] More preferably: the modified zeolite comprises the following components: by weight, 12 - 18 parts of N,N,N-trimethyl-1-ammonium adamantane hydroxide, 48 - 50 parts of deionized water, 1 - 2 parts of hexamethylenediamine, and 3 - 4 parts of fumed silica.

[0024] More preferably: the industrial parameters of the calcination are: temperature 600 - 650 °C, time 10 - 12 h.

[0025] The present invention prepares diacetone alcohol through an efficient continuous reaction process; and through an effective modification process, the performance of the catalyst is improved, while the conversion rate of diacetone alcohol is increased and the catalyst life is also extended. Specifically as follows:

[0026] Compared with the prior art, the advantages of the present invention are as follows:

[0027] (1) The cobalt ions in the composite catalyst obtained in the present invention can provide Lewis acidic sites; the uncoordinated nitrogen atoms can act as basic sites, and these sites can interact with acetone molecules. Under the action of the acidic sites, the carbonyl oxygen atom of acetone accepts a proton to form an enol cation intermediate; under the action of the basic sites, the carbonyl carbon atom of acetone loses a proton to form an enol anion intermediate, and the formed enol intermediate further reacts with another acetone molecule to form a C-C bond through a nucleophilic addition reaction to generate diacetone alcohol; the combination of acidic and basic sites improves the catalytic efficiency of the catalyst;

[0028] (2) The present invention loads a graphitic carbon nitride structure on the surface of alumina to enable better growth of the metal framework; and its nanoscale size can also increase the accessibility of active sites, shorten the diffusion path, reduce the generation of isopropylideneacetone, and improve the catalytic efficiency;

[0029] (3) During the catalytic reaction process, the relatively numerous silanol groups on the surface of the modified zeolite can further combine with the metal ions on the surface of the modified catalyst; due to the high specific surface area of the modified zeolite, it can provide more active sites for contact with acetone, increasing the possibility of the reaction; at the same time, the layered structure of the modified zeolite also avoids the aggregation of the modified catalyst. Description of the Drawings

[0030] Figure 1 It is a flow chart of the continuous reaction process of the present invention. Detailed Embodiments

[0031] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0032] It should be noted that the following parts are by weight, and there are no special restrictions on the purchase manufacturers of all raw materials involved in the present invention. Exemplarily, it includes: in the following embodiments, the average particle size of alumina is 20 nm, and the model is DK410-2; the CAS of 2-methylimidazole is 693-98-1; the CAS of melamine is 108-78-1; the CAS of cobalt(II) nitrate hexahydrate is 10026-22-9.

[0033] Example 1: A continuous reaction process for producing diacetone alcohol, comprising the following steps:

[0034] Step 1: Condensation reaction: Load a composite catalyst into the reactor, and then inject acetone into it through the feed pipe, react at 0 °C for 4 h, and cool to obtain a reaction mixture;

[0035] Step 2: First rectification: Transfer the reaction mixture to a rectification device, perform the first rectification at 90 °C, and collect the fraction of diacetone alcohol;

[0036] Step 3: Second rectification: Rectify the fraction of diacetone alcohol collected in Step 2 at 90 °C, and collect the crude product of diacetone alcohol;

[0037] Step 4: Third rectification: Rectify the crude product of diacetone alcohol collected in Step 3 at 98 °C to obtain diacetone alcohol;

[0038] Among them, the composite catalyst includes 10 parts of modified catalyst and 2 parts of modified zeolite;

[0039] The preparation process of the modified catalyst is:

[0040] S1: Put 20 parts of alumina and 10 parts of melamine into a chemical vapor deposition device, and then calcine them in a muffle furnace at 550 °C for 8 h, with a heating rate of 5 °C / min, to obtain modified alumina;

[0041] S2: (1) Disperse the modified alumina in ethanol and perform ultrasonic treatment to form suspension A. Among them, the mass fraction of the modified alumina in suspension A is 20 wt%; (2) Mix 10 parts of suspension A with 6 parts of cobalt nitrate hexahydrate ethanol solution, perform ultrasonic treatment, centrifugally separate, and then mix with 3 parts of 2-methylimidazole ethanol solution, perform ultrasonic treatment again, centrifuge, wash, and dry to obtain a preliminary catalyst;

[0042] S3: Add 10 parts of the preliminary catalyst to 3 parts of 2-methylimidazole ethanol solution, perform ultrasonic treatment, then add 5 parts of cobalt nitrate hexahydrate ethanol solution, stir for 3 h, and then centrifuge to separate the solid product, wash, and dry to obtain a modified catalyst;

[0043] The preparation process of the modified zeolite is as follows: Mix 12 parts of N,N,N-trimethyl-1-adamantylammonium hydroxide with 48 parts of deionized water, add 1 part of hexamethylenediamine and stir, then add 3 parts of fumed silica, stir for 12 h, then transfer to an autoclave, heat at 150 °C for 5 days, wash, dry, and calcine at 600 °C for 10 h to obtain the modified zeolite.

[0044] Example 2: A continuous reaction process for producing diacetone alcohol, including the following steps:

[0045] Step 1: Condensation reaction: Load a composite catalyst into the reactor, and then inject acetone into it through the feed pipe, react at 10 °C for 6 h, and cool to obtain a reaction mixture;

[0046] Step 2: First distillation: Transfer the reaction mixture to a distillation device and perform the first distillation at 95 °C to collect the fraction of diacetone alcohol;

[0047] Step 3: Second distillation: Distill the fraction of diacetone alcohol collected in Step 2 at 100 °C for the second distillation and collect the crude diacetone alcohol;

[0048] Step 4: Third distillation: Distill the crude diacetone alcohol collected in Step 3 at 100 °C for the third distillation to obtain diacetone alcohol;

[0049] Among them, the composite catalyst includes 12 parts of the modified catalyst and 3 parts of the modified zeolite;

[0050] The preparation process of the modified catalyst is as follows:

[0051] S1: Put 25 parts of alumina and 12 parts of melamine into a chemical vapor deposition device, then calcine them in a muffle furnace at 600 °C for 10 h, with a heating rate of 8 °C / min, to obtain modified alumina;

[0052] S2: (1) Disperse the modified alumina in ethanol and perform ultrasonic treatment to form suspension A, where the mass fraction of the modified alumina in suspension A is 30 wt%; (2) Mix 12 parts of suspension A with 8 parts of cobalt(II) nitrate hexahydrate ethanol solution, perform ultrasonic treatment, centrifuge, then mix with 4 parts of 2-methylimidazole ethanol solution, perform ultrasonic treatment again, centrifuge, wash, and dry to obtain a preliminary catalyst;

[0053] S3: Add 12 parts of the preliminary catalyst to 4 parts of 2-methylimidazole ethanol solution, perform ultrasonic treatment, then add 8 parts of cobalt(II) nitrate hexahydrate ethanol solution, stir for 4 h, then centrifuge to separate the solid product, wash, and dry to obtain a modified catalyst;

[0054] The preparation process of the modified zeolite is as follows: Mix 18 parts of N,N,N-trimethyl-1-adamantammonium hydroxide with 50 parts of deionized water, add 2 parts of hexamethylenediamine and stir, then add 4 parts of fumed silica, stir for 15 h, then transfer to an autoclave, heat at 180 °C for 6 days, wash, dry, and calcine at 650 °C for 12 h to obtain the modified zeolite.

[0055] Example 3: A continuous reaction process for producing diacetone alcohol, including the following steps:

[0056] Step 1: Condensation reaction: Load a composite catalyst into a reactor, then inject acetone into it through a feed pipe, react at 8 °C for 5 h, and cool to obtain a reaction mixture;

[0057] Step 2: First distillation: Transfer the reaction mixture to a distillation device and perform the first distillation at 95 °C to collect the fraction of diacetone alcohol;

[0058] Step 3: Second distillation: Distill the fraction of diacetone alcohol collected in Step 2 at 95 °C and collect the crude product of diacetone alcohol;

[0059] Step 4: Third distillation: Distill the crude product of diacetone alcohol collected in Step 3 at 100 °C to obtain diacetone alcohol;

[0060] Among them, the composite catalyst includes 11 parts of the modified catalyst and 2.5 parts of the modified zeolite;

[0061] The preparation process of the modified catalyst is as follows:

[0062] S1: Put 22 parts of alumina and 11 parts of melamine into a chemical vapor deposition device, then calcine them in a muffle furnace at 560 °C for 9 h, with a heating rate of 6 °C / min, to obtain modified alumina;

[0063] S2: (1) Disperse the modified alumina in ethanol and ultrasonically treat it to form suspension A, where the mass fraction of the modified alumina in suspension A is 25 wt%; (2) Mix 11 parts of suspension A with 7 parts of an ethanol solution of cobalt(II) nitrate hexahydrate, ultrasonically treat it, centrifuge and separate, then mix it with 3.5 parts of an ethanol solution of 2-methylimidazole, ultrasonically treat it again, centrifuge, wash, and dry to obtain a preliminary catalyst;

[0064] S3: Add 11 parts of the preliminary catalyst to 3.5 parts of an ethanol solution of 2-methylimidazole, ultrasonically treat it, then add 6 parts of an ethanol solution of cobalt(II) nitrate hexahydrate, stir for 3.5 h, then centrifuge and separate the solid product, wash, and dry to obtain a modified catalyst;

[0065] The preparation process of the modified zeolite is as follows: Mix 15 parts of N,N,N-trimethyl-1-ammonium hydroxide with 50 parts of deionized water, add 1.5 parts of hexanediamine and stir, then add 3.5 parts of fumed silica, stir for 13 h, then transfer it to an autoclave, heat it at 160 °C for 6 days, wash, dry, and calcine it at 620 °C for 11 h to obtain the modified zeolite.

[0066] Example 4: A continuous reaction process for producing diacetone alcohol, comprising the following steps:

[0067] Step 1: Condensation reaction: Load a composite catalyst into a reactor, then inject acetone into it through a feed pipe, react at 0 °C for 4 h, and cool to obtain a reaction mixture;

[0068] Step 2: First distillation: Transfer the reaction mixture to a distillation device and perform the first distillation at 90 °C to collect the fraction of diacetone alcohol;

[0069] Step 3: Second distillation: Distill the fraction of diacetone alcohol collected in Step 2 at 90 °C for the second distillation and collect the crude product of diacetone alcohol;

[0070] Step 4: Third distillation: Distill the crude product of diacetone alcohol collected in Step 3 at 98 °C for the third distillation to obtain diacetone alcohol;

[0071] Among them, the composite catalyst includes 10 parts of the modified catalyst and 2 parts of the modified zeolite;

[0072] The preparation process of the modified catalyst is as follows:

[0073] S1: Put 25 parts of alumina and 12 parts of melamine into a chemical vapor deposition device, and then calcine them in a muffle furnace at 600 °C for 10 h, with a heating rate of 8 °C / min, to obtain modified alumina;

[0074] S2: (1) Disperse the modified alumina in ethanol and perform ultrasonic treatment to form suspension A, where the mass fraction of the modified alumina in suspension A is 30 wt%; (2) Mix 10 parts of suspension A with 8 parts of cobalt nitrate hexahydrate ethanol solution, perform ultrasonic treatment, centrifuge, and then mix with 4 parts of 2-methylimidazole ethanol solution, perform ultrasonic treatment again, centrifuge, wash, and dry to obtain a preliminary catalyst;

[0075] S3: Add 12 parts of the preliminary catalyst to 4 parts of 2-methylimidazole ethanol solution, perform ultrasonic treatment, then add 8 parts of cobalt nitrate hexahydrate ethanol solution, stir for 4 h, and then centrifuge to separate the solid product, wash, and dry to obtain a modified catalyst;

[0076] The preparation process of the modified zeolite is as follows: Mix 15 parts of N,N,N-trimethyl-1-adamantammonium hydroxide with 50 parts of deionized water, add 1.5 parts of hexamethylenediamine and stir, then add 3.5 parts of fumed silica, stir for 13 h, then transfer to an autoclave, heat at 160 °C for 6 days, wash, dry, and calcine at 620 °C for 11 h to obtain the modified zeolite.

[0077] Comparative Example 1: Replace the composite catalyst with the basic catalyst barium hydroxide, and the rest is the same as in Example 4.

[0078] Comparative Example 2: In the composite catalyst, do not add the modified zeolite, and the rest is the same as in Example 4.

[0079] Comparative Example 3: Do not modify the alumina, and the rest is the same as in Example 4. Specifically as follows:

[0080] Step 1: Condensation reaction: Load the composite catalyst into the reactor, and then inject acetone into it through the feed pipe, react at 0 °C for 4 h, and cool to obtain a reaction mixture;

[0081] Step 2: First distillation: Transfer the reaction mixture to a distillation device and perform the first distillation at 90 °C to collect the fraction of diacetone alcohol;

[0082] Step 3: Second distillation: Distill the fraction of diacetone alcohol collected in Step 2 at 90 °C for the second distillation and collect the crude product of diacetone alcohol;

[0083] Step 4: Third distillation: Distill the crude product of diacetone alcohol collected in Step 3 at 98 °C for the third distillation to obtain diacetone alcohol;

[0084] Among them, the composite catalyst includes 10 parts of alumina and 2 parts of modified zeolite;

[0085] The preparation process of the modified zeolite is as follows: Mix 15 parts of N,N,N-trimethyl-1-adamantylammonium hydroxide with 50 parts of deionized water, add 1.5 parts of hexamethylenediamine and stir, then add 3.5 parts of fumed silica, stir for 13 h, then transfer to an autoclave, heat at 160 °C for 6 days, wash, dry, and calcine at 620 °C for 11 h to obtain the modified zeolite.

[0086] Detection experiment: (1) Detect the content of each component in the reaction mixture after the condensation reaction in Examples 1-4 and Comparative Examples 1-2, and calculate the conversion rate of diacetone alcohol; (2) Detect the conversion rate of diacetone alcohol after the catalyst is used for 80 h; the obtained data are shown in the following table:

[0087]

[0088] Table 1

[0089] Conclusion: The present invention prepares diacetone alcohol through an efficient continuous reaction process; moreover, through an effective modification process, the performance of the catalyst is improved, while the conversion rate of diacetone alcohol is increased and the catalyst life is also extended. Compared with the traditional basic solid catalyst used in Comparative Example 1, the conversion rate of diacetone alcohol is increased when the composite catalyst is used in Examples 1-4; moreover, after 80 h of use, the result of the whole reaction does not change much, indicating that the obtained catalyst has a high life; in Comparative Example 2, no modified zeolite is added, lacking the layered zeolite structure, which reduces the catalytic efficiency of the whole reaction and the performance declines; in Comparative Example 2, the alumina is not modified, and the performance declines.

[0090] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A continuous reaction process for producing diacetone alcohol, characterized in that: It includes the following steps: Step 1: Condensation reaction: Load a composite catalyst into a reactor, then inject acetone into it through a feeding pipe, react at 0 - 10 °C for 4 - 6 h, and cool to obtain a reaction mixture. Step 2: First distillation: Transfer the reaction mixture to a distillation device and perform the first distillation at 90 - 95 °C to collect the fraction of diacetone alcohol. Step 3: Second distillation: Distill the fraction of diacetone alcohol collected in Step 2 at 90 - 100 °C to collect the crude product of diacetone alcohol. Step 4: Third distillation: Distill the crude product of diacetone alcohol collected in Step 3 at 98 - 100 °C to obtain diacetone alcohol.

2. The continuous reaction process for producing diacetone alcohol according to claim 1, characterized in that: The composite catalyst includes the following components: by weight, 10 - 12 parts of a modified catalyst and 2 - 3 parts of modified zeolite.

3. The continuous reaction process for producing diacetone alcohol according to claim 2, characterized in that: The preparation process of the modified catalyst is as follows: S1: Put alumina and melamine into a chemical vapor deposition device, and then calcine in a muffle furnace to obtain modified alumina. S2: (1) Disperse the modified alumina in ethanol and perform ultrasonic treatment to form suspension A; (2) Mix suspension A with an ethanol solution of cobalt(II) nitrate hexahydrate, perform ultrasonic treatment, centrifugally separate, then add it to an ethanol solution of 2 - methylimidazole, perform ultrasonic treatment again, centrifuge, wash, and dry to obtain a preliminary catalyst. S3: Add the preliminary catalyst to an ethanol solution of 2 - methylimidazole, perform ultrasonic treatment, then add an ethanol solution of cobalt(II) nitrate hexahydrate, stir for 3 - 4 h, then centrifugally separate the solid product, wash, and dry to obtain the modified catalyst.

4. A continuous reaction process for producing diacetone alcohol according to claim 3, characterized in that: The process parameters of the calcination are: temperature 550 - 600 °C, heating rate 5 - 8 °C / min, time 8 - 10 h.

5. A continuous reaction process for producing diacetone alcohol according to claim 3, characterized in that: The raw materials of the modified alumina include the following components: by weight, 10 - 12 parts of melamine and 25 - 20 parts of alumina; the preliminary catalyst includes the following components: by weight, 10 - 12 parts of suspension A, 6 - 8 parts of an ethanol solution of cobalt(II) nitrate hexahydrate, and 3 - 4 parts of an ethanol solution of 2 - methylimidazole; the modified catalyst includes the following components: by weight, 10 - 12 parts of the preliminary catalyst, 3 - 4 parts of an ethanol solution of 2 - methylimidazole, and 5 - 8 parts of an ethanol solution of cobalt(II) nitrate hexahydrate.

6. A continuous reaction process for producing diacetone alcohol according to claim 3, characterized in that: The mass fraction of the modified alumina in suspension A is 20 - 30 wt%; in the ethanol solution of cobalt(II) nitrate hexahydrate, the mass fraction of cobalt(II) nitrate hexahydrate is 10 - 12 wt%; in the ethanol solution of 2 - methylimidazole, the mass fraction of 2 - methylimidazole is 8 - 10 wt%.

7. A continuous reaction process for producing diacetone alcohol according to claim 2, characterized in that: The preparation process of the modified zeolite is: Mix N,N,N - trimethyl - 1 - adamantylammonium hydroxide with deionized water, add hexamethylenediamine and stir, then add fumed silica, stir for 12 - 15 h, then transfer to an autoclave, heat at 150 - 180 °C for 5 - 6 days, wash, dry, and calcine to obtain the modified zeolite.

8. A continuous reaction process for producing diacetone alcohol according to claim 7, characterized in that: The modified zeolite includes the following components: by weight, 12 - 18 parts of N,N,N - trimethyl - 1 - adamantylammonium hydroxide, 48 - 50 parts of deionized water, 1 - 2 parts of hexamethylenediamine, and 3 - 4 parts of fumed silica.

9. A continuous reaction process for producing diacetone alcohol according to claim 7, characterized in that: The industrial parameters of the roasting are as follows: temperature 600 - 650 °C, time 10 - 12 h.

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