A process for the preparation of anti-caking 1,3-cyclohexanedione

Abstract

The application provides a method for preparing anti-caking 1,3-cyclohexanedione, which comprises the following steps: (1) in a solvent, resorcinol sodium salt and hydrogen are subjected to hydrogenation reaction under the action of a catalyst, and after the reaction is completed, the catalyst is removed by filtration to obtain a hydrogenation solution; (2) an anti-caking agent is added into the hydrogenation solution to obtain a reaction solution containing the anti-caking agent; (3) acid is added into the reaction solution containing the anti-caking agent to obtain an acidified solution; and (4) the acidified solution is filtered to obtain a wet product, and the wet product is dried to obtain 1,3-cyclohexanedione finished product. The method does not need to additionally increase new equipment and does not additionally increase equipment cost. The method is simple in process, small in change to the original process and strong in operability. The 1,3-cyclohexanedione product is active in nature, and is easily deteriorated if not properly handled, thereby affecting the use of downstream customers. The method does not affect the quality of the product after the use of the anti-caking agent, and does not affect the use of downstream customers.

Description

Technical Field

[0001] This invention belongs to the field of chemical anti-caking agents, and specifically relates to a method for preparing anti-caking 1,3-cyclohexanedione. Background Technology

[0002] In existing technologies, there are three most common methods for dealing with product clumping:

[0003] 1. Directly add anti-caking agents to the product and mix the product and anti-caking agents evenly using equipment such as a mixer or screw conveyor to prevent product agglomeration. For example, the invention patent application CN114031456A of Anhui Haixiang New Material Technology Co., Ltd., entitled "Preparation Method and Application of an Anti-caking Compound Fertilizer Active Additive", discloses a preparation method and application of an anti-caking compound fertilizer active additive. This anti-caking compound fertilizer active additive includes talc, kaolin, amine salt, sodium dodecyl sulfate, alkyl naphthalene sulfonate, fatty alcohol polyoxyethylene ether, polyvinyl acetate, mineral oil, paraffin wax, organosilicon, magnesium sulfate, and a composite emulsifier. The magnesium sulfate is a 3% magnesium sulfate aqueous solution. The anti-caking compound fertilizer active additive of this invention can effectively prevent compound fertilizer from agglomerating.

[0004] This method has the following drawbacks: 1. Mixing the anti-caking agent with the product using a mixer or screw conveyor involves mixing the anti-caking agent and the product (e.g., fertilizer) as both are solid particles. While mixing via screw conveyor provides some mixing, it's impossible to evenly coat the anti-caking agent onto the surface of the product (e.g., fertilizer), thus affecting the effectiveness of the anti-caking agent. 2. The addition of additional mixing equipment (e.g., screw conveyor equipment) increases equipment costs.

[0005] 2. Design specialized anti-caking equipment to prevent products from clumping during the drying process. The invention patent application CN217093121U of Shanxi Aishidan Biotechnology Co., Ltd., entitled "A Processing Device for Powdered Water-Soluble Fertilizer to Avoid Agglomeration," discloses a processing device for powdered water-soluble fertilizer to avoid agglomeration. This device includes a mixing processing box and an anti-agglomeration mechanism. The mixing processing box is equipped with the anti-agglomeration mechanism. A first drive motor is fixedly installed at the top of the mixing processing box. A rotating tube is fixedly sleeved in the middle of the driven gear. An electric heating wire is riveted to the inner wall of the rotating tube. A second drive motor is installed at the top of the rotating tube. A rotating rod is rotatably connected to the top of the rotating tube via a bearing. The bottom end of the rotating rod extends into the interior of the rotating tube. Fan blades matching the electric heating wire are riveted to the side wall of the rotating rod. A driving bevel gear is welded to other positions on the side wall of the rotating rod. Driven bevel gears are meshed with both sides of the driving bevel gear. A stirring tube is fixedly installed on one side wall of the driven bevel gear, and a stirring blade is fixedly installed on the other side wall of the stirring tube. This invention effectively prevents the powdered water-soluble fertilizer raw materials from absorbing moisture and agglomerating, ensuring thorough mixing and improving processing efficiency.

[0006] The disadvantages of this method include: 1. It only states that the product will not clump during the drying process, but does not mention the clumping situation during the storage process after the product is dried; 2. It uses unconventional equipment, requires customization, and has a high cost.

[0007] III. Product Modification. Han Tao's invention patent application CN114507509A, "A Graphene-Modified Disodium Hydrogen Phosphate Dodecahydrate Hydrated Phase Change Thermal Storage Material and Its Preparation Method," uses disodium hydrogen phosphate dodecahydrate as the base material, modifies it with graphene, and then combines it with nucleating agents, thickeners, and anti-caking agents. With the assistance of these additives, the resulting hydrated phase change thermal storage material has a high phase change exothermic value, excellent anti-caking performance, high stability, a simple preparation process, and the resulting product is easy to package and produce, making it suitable for use in solar energy storage and thermal management of electronic devices.

[0008] The disadvantages of this method include: it is suitable for modifying materials where high purity is not required, but it is not suitable for preventing compounds from caking.

[0009] Currently, the selective hydrogenation of resorcinol to prepare 1,3-cyclohexanedione is the most mature and widely used production process for 1,3-cyclohexanedione. This process mainly consists of three steps: neutralization, hydrogenation, and acidification rearrangement. The acidification rearrangement reaction solution is cooled, crystallized, filtered, and dried to obtain the finished 1,3-cyclohexanedione product.

[0010] The moisture content of 1,3-cyclohexanedione finished products is generally below 0.5 wt%. Due to the combined effects of the particles themselves and external factors, moisture inside and on the surface of 1,3-cyclohexanedione molecules moves to the surface of 1,3-cyclohexanedione crystals, causing the 1,3-cyclohexanedione to dissolve and recrystallize. This forms crystal bridges at the contact points between crystal particles, causing the crystals to stick together, lose their fluidity, and gradually form hard lumps. The agglomeration of solid 1,3-cyclohexanedione seriously affects its sales and downstream use, which is a major problem in the 1,3-cyclohexanedione industry.

[0011] No methods for preventing caking of 1,3-cyclohexanedione products have been found in the existing technology. Therefore, there is an urgent need in the field to develop a simple and easy-to-operate method for preventing caking of 1,3-cyclohexanedione. Summary of the Invention

[0012] The purpose of this invention is to provide a method for preparing anti-caking 1,3-cyclohexanedione.

[0013] A first aspect of the present invention provides a method for preparing an anti-caking 1,3-cyclohexanedione, the method comprising the steps of:

[0014] (1) In the solvent, sodium resorcinol salt and hydrogen gas undergo a hydrogenation reaction under the action of a catalyst. After the reaction is completed, the catalyst is removed by filtration to obtain the hydrogenated feed solution.

[0015] (2) Add an anti-caking agent to the hydrogenated feed solution to obtain a reaction solution containing the anti-caking agent;

[0016] (3) Acid is added to the reaction solution containing the anti-caking agent to obtain an acidified solution;

[0017] (4) Filter the acidified liquid to obtain a wet product, and dry the wet product to obtain 1,3-cyclohexanedione product.

[0018] In one or more embodiments, the anticaking agent is selected from one or more of kaolin, talc, sodium dodecylbenzenesulfonate, and sodium octadecyl sulfate.

[0019] In one or more embodiments, in step (2), the amount of anti-caking agent used is 1 to 5 wt‰ of the theoretical mass of 1,3-cyclohexanedione.

[0020] In one or more embodiments, the water content in the 1,3-cyclohexanedione product is ≤0.50 wt%, preferably ≤0.31 wt%.

[0021] In one or more embodiments, the sodium resorcinol salt is prepared by reacting resorcinol with sodium hydroxide in a molar ratio of 1:(1 to 1.5); preferably, the amount of catalyst used is 1.5 to 5.0 wt% of the mass of resorcinol.

[0022] In one or more embodiments, the solvent is water; preferably, the molar ratio of resorcinol to water is 1:(10-25).

[0023] In one or more embodiments, the reaction temperature is 20–50°C.

[0024] In one or more embodiments, the reaction pressure is 0.5 to 1.5 MPa.

[0025] In one or more embodiments, the reaction is carried out under a protective gas, preferably nitrogen.

[0026] In one or more embodiments, the reaction proceeds for 0.5 to 5 hours.

[0027] In one or more embodiments, the catalyst includes a support and an active component supported on the support.

[0028] In one or more embodiments, the active component of the catalyst is nickel oxide.

[0029] In one or more embodiments, the catalyst is loaded with 13 to 15 wt% nickel oxide.

[0030] In one or more embodiments, the catalyst is supported by a zeolite molecular sieve.

[0031] In one or more embodiments, the acid is added at 0–5°C.

[0032] In one or more embodiments, the acid is selected from one or more of hydrochloric acid, sulfuric acid, phosphoric acid, and nitric acid.

[0033] In one or more embodiments, the concentration of the acid is 25–35 wt%.

[0034] In one or more embodiments, acid is added to acidify the acidified solution to a pH of 2.0 to 3.0.

[0035] In one or more embodiments, after acidification, the acidified solution is stirred at 0–5°C for 0.5–5 hours.

[0036] In one or more embodiments, the wet product is dried at 40–65°C.

[0037] In one or more embodiments, the wet product is dried under vacuum.

[0038] In one or more embodiments, the wet product is dried for 4 to 6 hours.

[0039] In one or more embodiments, in step (2), the theoretical mass fraction of 1,3-cyclohexanedione in the hydrogenated feed solution is 18 to 34 wt%.

[0040] In one or more embodiments, in step (1), the pressure inside the reactor is evacuated to -0.08 to -0.12 MPa, nitrogen is introduced to the reactor to a pressure of 0.8 to 1.2 MPa, and this process is repeated 2 to 4 times. Then, hydrogen is introduced to the reactor to a pressure of 0.5 to 1.5 MPa. Preferably, when the pressure inside the reactor drops to 0.1 to 0.3 MPa, hydrogen is reintroduced to adjust the pressure inside the reactor to 0.5 to 1.5 MPa, and this operation is repeated until the pressure inside the reactor no longer decreases. Preferably, if the pressure inside the reactor does not decrease within 10 to 20 minutes, the reaction is continued at a constant temperature for 0.5 to 5 hours. Detailed Implementation

[0041] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0042] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0043] In this document, the terms “contains,” “includes,” “containing,” and similar terms encompass the meanings of “basically composed of” and “composed of.” For example, when this document discloses “A contains B and C,” “A is basically composed of B and C” and “A is composed of B and C” should be considered as having been disclosed in this document.

[0044] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0045] Unless otherwise specified, percentages refer to mass percentages and proportions refer to mass ratios in this article.

[0046] In this document, when describing embodiments or examples, it should be understood that it is not intended to limit the invention to those embodiments or examples. Rather, all alternatives, modifications, and equivalents of the methods and materials described herein are covered within the scope defined by the claims.

[0047] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0048] This invention provides a method for preparing anti-caking 1,3-cyclohexanedione. In this method, a certain amount of anti-caking agent is added to the hydrogenation solution before the acidification step in the preparation of 1,3-cyclohexanedione. This method does not require additional equipment, is simple (basically does not change the original process), is highly operable, and does not affect the quality of the product.

[0049] This invention provides a method for preparing anti-caking 1,3-cyclohexanedione, the method comprising the steps of:

[0050] (1) In the solvent, sodium resorcinol salt and hydrogen gas undergo a hydrogenation reaction under the action of a catalyst. After the reaction is completed, the catalyst is removed by filtration to obtain the hydrogenated feed solution.

[0051] (2) Add an anti-caking agent to the hydrogenation solution to obtain a reaction solution containing the anti-caking agent;

[0052] (3) Acid is added to the reaction solution containing the anti-caking agent to obtain an acidified solution;

[0053] (4) Filter the acidified liquid to obtain a wet product, and dry the wet product to obtain 1,3-cyclohexanedione product.

[0054] In step (1), sodium resorcinol can be prepared by reacting resorcinol with sodium hydroxide in a molar ratio of 1:(1 to 1.5), for example, the molar ratio of resorcinol to sodium hydroxide can be 1:1.1, 1:1.2, 1:1.3, or 1:1.4. The solvent can be water. The molar ratio of resorcinol to water can be 1:(10 to 25), for example, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18, 1:19, 1:20, 1:21, 1:22, 1:23, or 1:24. The amount of catalyst can be 1.5 to 5.0 wt% of the mass of resorcinol, for example, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, or 4.5 wt%. During the reaction, 1 mol of resorcinol requires 1.95 to 2.10 g of hydrogen gas for hydrogenation, for example, 1.95 g, 2.00 g, 2.05 g, or 2.10 g.

[0055] The reaction temperature can be 0–50℃, for example 5℃, 10℃, 15℃, 20℃, 25℃, 30℃, 35℃, 40℃, 45℃. The reaction pressure can be 0.5–1.5 MPa, for example 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa, 1.0 MPa, 1.1 MPa, 1.2 MPa, 1.3 MPa, 1.4 MPa, 1.5 MPa. The reaction can proceed for 0.5–5 hours, for example 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours. The reaction is preferably carried out under a protective gas atmosphere, preferably nitrogen.

[0056] The catalyst of this invention comprises a support and an active component supported on the support. The active component of the catalyst is nickel oxide. The support for the catalyst is a zeolite molecular sieve. The loading of nickel oxide in the catalyst can be 13-15 wt%, for example, 13 wt%, 14 wt%, or 15 wt%. The preparation of the catalyst can also be referenced in invention patent application CN114073975A.

[0057] In step (1), the pressure inside the reactor is evacuated to -0.08 to -0.12 MPa, nitrogen is introduced to bring the pressure inside the reactor to 0.8 to 1.2 MPa, and this process is repeated 2 to 4 times. Then, hydrogen is introduced to bring the pressure inside the reactor to 0.5 to 1.5 MPa. When the pressure inside the reactor drops to 0.1 to 0.3 MPa, hydrogen is introduced again to adjust the pressure inside the reactor to 0.5 to 1.5 MPa. This operation is repeated until the pressure inside the reactor no longer decreases. If the pressure inside the reactor does not decrease within 10 to 20 minutes, the reaction is continued at a constant temperature for 0.5 to 5 hours, for example, for 1 hour, 2 hours, 3 hours, or 4 hours. In some embodiments, in step (1), the pressure inside the reactor is evacuated to -0.1 MPa using a vacuum pump, nitrogen is introduced to bring the pressure inside the reactor to 1.0 MPa, this process is repeated 3 times, and then hydrogen is introduced to bring the pressure inside the reactor to 0.5 to 1.5 MPa. The stirring speed of the reactor can be 600–1000 rpm, for example, 700 rpm, 800 rpm, or 900 rpm. When the hydrogen pressure drops to 0.1–0.3 MPa, the pressure is readjusted to 0.5–1.5 MPa, and this operation is repeated until the pressure inside the reactor no longer decreases. After the pressure inside the reactor stabilizes, it is kept at this temperature for 1 hour to complete the reaction.

[0058] In step (2), the anti-caking agent can be selected from one or more of kaolin, talc, sodium dodecylbenzenesulfonate, and sodium octadecyl sulfate, preferably sodium dodecylbenzenesulfonate. The amount of anti-caking agent can be added according to the mass of the product 1,3-cyclohexanedione. The amount of anti-caking agent can be 1 to 5 wt‰ of the theoretical mass of 1,3-cyclohexanedione, for example, 1 wt‰, 1.5 wt‰, 2 wt‰, 2.5 wt‰, 3 wt‰, 3.5 wt‰, 4 wt‰, 4.5 wt‰, 5 wt‰, preferably 1 to 2 wt‰. Before acidification, since the reaction system only contains the hydrogenation intermediate of sodium resorcinol salt and does not actually contain 1,3-cyclohexanedione, the content of 1,3-cyclohexanedione in the hydrogenation solution is expressed by the theoretical mass of 1,3-cyclohexanedione. The theoretical mass of 1,3-cyclohexanedione in the hydrogenation solution can be determined by high performance liquid chromatography (HPLC). During the determination process, an acidic mobile phase is used to acidify the hydrogenation intermediate of sodium resorcinol to 1,3-cyclohexanedione, and then the theoretical mass of 1,3-cyclohexanedione in the hydrogenation feed solution is determined chromatographically. The theoretical mass fraction of 1,3-cyclohexanedione in the hydrogenation feed solution can be 18–34 wt%, for example 19 wt%, 20 wt%, 21 wt%, 22 wt%, 23 wt%, 24 wt%, 25 wt%, 26 wt%, 27 wt%, 28 wt%, 29 wt%, 30 wt%, 31 wt%, 32 wt%, 33 wt%, preferably 20–25 wt%. Adding the anti-caking agent of this invention to the hydrogenation feed solution allows the CHD particles in the obtained 1,3-cyclohexanedione (CHD) product to be coated by the anti-caking agent of this invention, blocking the crystal bridging effect between CHD particles, thus preventing CHD from agglomerating. Furthermore, the anti-caking agent of the present invention can block the formation of hydrogen bonds between CHD and water, resulting in a decrease in the water content of CHD and further reducing the agglomeration of the 1,3-cyclohexanedione product.

[0059] In step (3), acid may be added at 0–5°C. The acid may be selected from one or more of hydrochloric acid, sulfuric acid, phosphoric acid, and nitric acid, preferably hydrochloric acid. The concentration of the acid may be 25–35 wt%, for example, 25 wt%, 27 wt%, 29 wt%, 31 wt%, 33 wt%, or 35 wt%. In some embodiments, the acid is hydrochloric acid, and the concentration of hydrochloric acid is 29–33 wt%. Acidification is performed until the pH of the acidified solution is 2.0–3.0, for example, pH 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, or 2.9. In some embodiments, the addition of acid is stopped when the pH of the acidified solution is 2.5 ± 0.1. After acidification, the acidified solution is stirred at 0–5°C for 0.5–5 hours. In some embodiments, after acidification, the acidified solution is stirred at 3–5°C for 0.8–1.2 hours.

[0060] In step (4), the water content in the 1,3-cyclohexanedione product is ≤0.50 wt%, for example ≤0.40 wt%, ≤0.35 wt%, ≤0.34 wt%, ≤0.33 wt%, ≤0.32 wt%, ≤0.31 wt%, ≤0.30 wt%, ≤0.20 wt%, ≤0.10 wt%, preferably ≤0.33 wt%, ≤0.32 wt%, ≤0.31 wt%, or ≤0.30 wt%. The wet product can be dried at 40–65°C, for example, at 45°C, 50°C, 55°C, or 60°C, preferably at 40–50°C. In some embodiments, the wet product is dried under vacuum. The wet product can be dried for 4–6 hours, for example, 5 hours.

[0061] The present invention has the following beneficial effects:

[0062] 1. The method of the present invention does not require the addition of new equipment and does not increase equipment costs;

[0063] 2. The method of the present invention is simple, requires little change to the original process, and is highly operable;

[0064] 3. 1,3-Cyclohexanedione is a highly reactive product, and improper handling can easily lead to product deterioration, affecting downstream customers' use. The method of this invention, after using an anti-caking agent, will not affect the quality of the product and will not affect downstream customers' use.

[0065] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. Percentages and parts are by weight unless otherwise stated.

[0066] Preparation Example

[0067] The catalyst was prepared according to the following steps:

[0068] 1. Catalyst precursor synthesis

[0069] Add 250 mL of deionized water to a 2 L beaker, turn on the mechanical stirrer, set the speed to 600 r / min, and slowly heat to 85 °C. Then, add the prepared 0.4 mol / L nickel nitrate aqueous solution and 0.4 mol / L sodium carbonate aqueous solution to the beaker in a continuous co-flow manner and co-precipitate for 2 h. Add 4 g of mesoporous zeolite molecular sieve powder as a carrier, stir again at 85 °C for 45 min, filter, wash the filter cake with deionized water, put the wet filter cake into an oven and dry at 105 °C for 8 h, grind, and sieve until the particle size is less than 60 μm.

[0070] 2. Catalyst calcination and shaping.

[0071] The ground and sieved powder was placed in a tube furnace and calcined at 550°C for 3 hours. Then, a mixture of nitrogen and hydrogen was introduced to carry out a reduction reaction. After reacting for 4 hours, the temperature was naturally lowered to prepare a supported nickel catalyst with nickel oxide as the active component and zeolite molecular sieve as the support. It does not spontaneously combust when exposed to air.

[0072] The catalyst support is a mesoporous zeolite molecular sieve, and the nickel oxide loading in the catalyst is 14 wt%, with a specific surface area of ​​56 m². 2 / g, with an average pore size of 3.9nm.

[0073] Example 1

[0074] 1. Hydrogenation reduction

[0075] 220.0 g of resorcinol (2 mol), 88 g of sodium hydroxide (2.2 mol), 648 g of water (36 mol), and 10 g of the catalyst prepared in the preparation example were added to a 1 L high-pressure reactor. After assembling the reactor, the pressure inside the reactor was evacuated to -0.1 MPa using a vacuum pump. Nitrogen gas was then introduced until the pressure inside the reactor reached 1.0 MPa, and this process was repeated three times. Then, hydrogen gas was introduced until the pressure inside the reactor reached 1.5 MPa. After a leak test was passed, the temperature of the reactor was adjusted to 40 °C and the rotation speed was set to 800 rpm. When the pressure inside the reactor dropped to 0.2 MPa, hydrogen gas was introduced again to restore the pressure to 1.5 MPa. This operation was repeated until the pressure inside the reactor no longer decreased within 15 minutes. Then, the reactor was kept at this temperature for 1 hour to complete the reaction.

[0076] 2. Add anti-caking agent and acidify to induce crystallization.

[0077] The liquid in the reactor was removed and filtered to remove the catalyst. The resulting liquid was called hydrogenated liquid. HPLC quantitative analysis showed that the theoretical CHD content in the liquid was 22.33 wt%. The hydrogenated liquid was divided into two equal portions (hydrogenated liquid A and hydrogenated liquid B), with each portion containing a theoretical CHD mass of 107.21 g. Hydrogenated liquid A was placed in a four-necked flask, and 0.22 g of sodium dodecylbenzenesulfonate was added. Approximately 31 wt% hydrochloric acid (approximately 98 g) was slowly added under stirring at 5°C. When the pH of the liquid reached approximately 2.5 ± 0.1, the addition of hydrochloric acid was stopped, and stirring was continued at 5°C for 1 hour.

[0078] 3. Drying wet products

[0079] The acidified solution from step 2 was filtered to obtain a wet product. The wet product was then vacuum dried at 40°C for 5 hours to obtain the CHD product. The purity of the CHD product was 99.99%, and the water content was 0.30 wt% (measured using a moisture titrator). The product did not clump when stored at 15°C under nitrogen for 12 months.

[0080] Example 2

[0081] The method of Example 1 was repeated, except that 0.11g of sodium dodecylbenzenesulfonate was added.

[0082] The purity of the obtained CHD product is 99.99%, and the water content is 0.31 wt% (measured using a moisture titrator). The product does not clump when stored at 15°C under nitrogen for 12 months.

[0083] Example 3

[0084] The method of Example 1 was repeated, except that 0.55g of sodium dodecylbenzenesulfonate was added.

[0085] The purity of the obtained CHD product is 99.98%, and the water content is 0.26 wt% (measured using a moisture titrator). The product does not clump when stored at 15°C under nitrogen for 12 months.

[0086] Example 4

[0087] The method of Example 1 was repeated, except that instead of adding 0.22g of sodium dodecylbenzenesulfonate, 0.33g of kaolin was added.

[0088] The purity of the obtained CHD product is 99.99%, and the water content is 0.29 wt% (measured using a moisture titrator). The product does not clump when stored at 15°C under nitrogen for 12 months.

[0089] Example 5

[0090] The method of Example 1 was repeated, except that instead of adding 0.22g of sodium dodecylbenzenesulfonate, 0.33g of talc was added.

[0091] The purity of the obtained CHD product is 99.99%, and the water content is 0.30 wt% (measured using a moisture titrator). The product will not clump when stored at 15°C under nitrogen for 12 months.

[0092] Example 6

[0093] The method of Example 1 was repeated, except that instead of adding 0.22g of sodium dodecylbenzenesulfonate, 0.33g of sodium octadecyl sulfate was added.

[0094] The purity of the obtained CHD product is 99.98%, and the water content is 0.28 wt% (measured using a moisture titrator). The product does not clump when stored at 15°C under nitrogen for 12 months.

[0095] Comparative Example

[0096] 1. Acidification and crystallization

[0097] The hydrogenated feed solution B obtained in the example was placed in a four-necked flask, and about 31 wt% hydrochloric acid (about 98 g) was slowly added under stirring at 5°C. When the pH of the feed solution was about 2.5 ± 0.1, the addition of hydrochloric acid was stopped, and stirring was continued at 5°C for 1 hour.

[0098] 2. Drying wet products

[0099] The acidified solution from step 1 was filtered to obtain a wet product. The wet product was then vacuum dried at 40°C for 5 hours to obtain the CHD product. The purity of the CHD product was 99.99%, and the water content was 0.32 wt% (measured using a moisture titrator). The product began to clump after 20 days of storage at 15°C under nitrogen.

Claims

1. A method for preparing anti-caking 1,3-cyclohexanedione, characterized in that, The method includes the following steps: (1) In the solvent, sodium resorcinol salt and hydrogen gas undergo a hydrogenation reaction under the action of a catalyst. After the reaction is completed, the catalyst is removed by filtration to obtain the hydrogenated feed solution. (2) Add an anti-caking agent to the hydrogenated feed solution to obtain a reaction solution containing the anti-caking agent; (3) Acid is added to the reaction solution containing the anti-caking agent to obtain an acidified solution; (4) Filter the acidified liquid to obtain a wet product, and dry the wet product to obtain 1,3-cyclohexanedione product.

2. The method as described in claim 1, characterized in that, The anti-caking agent is selected from one or more of kaolin, talc, sodium dodecylbenzenesulfonate, and sodium octadecyl sulfate.

3. The method as described in claim 1, characterized in that, In step (2), the amount of anti-caking agent used is 1 to 5 wt‰ of the theoretical mass of 1,3-cyclohexanedione.

4. The method as described in claim 1, characterized in that, The water content in the 1,3-cyclohexanedione product is ≤0.50wt%, preferably ≤0.31wt%.

5. The method as described in claim 1, characterized in that, Step (1) has one or more of the following characteristics: The sodium resorcinol salt is prepared by reacting resorcinol with sodium hydroxide in a molar ratio of 1:(1 to 1.5); preferably, the amount of catalyst used is 1.5 to 5.0 wt% of the mass of resorcinol. The solvent is water; preferably, the molar ratio of resorcinol to water is 1:(10-25); The reaction temperature is 20–50℃; The reaction pressure is 0.5–1.5 MPa; The reaction is carried out under a protective gas, preferably nitrogen; The reaction proceeds for 0.5 to 5 hours.

6. The method as described in claim 1, characterized in that, The catalyst includes a support and an active component supported on the support; Preferably, the active component of the catalyst is nickel oxide; preferably, the loading of nickel oxide in the catalyst is 13-15 wt%. Preferably, the catalyst support is a zeolite molecular sieve.

7. The method as described in claim 1, characterized in that, Step (3) has one or more of the following characteristics: The acid is added at 0–5°C; The acid is selected from one or more of hydrochloric acid, sulfuric acid, phosphoric acid, and nitric acid; The concentration of the acid is 25-35 wt%. Acidification is performed until the pH of the acidified solution is 2.0–3.0; After acidification, the acidified solution is stirred at 0-5°C for 0.5-5 hours.

8. The method as described in claim 1, characterized in that, Step (4) has one or more of the following characteristics: The wet product is dried at 40–65°C; The wet product is dried under vacuum; The wet product is dried for 4–6 hours.

9. The method as described in claim 1, characterized in that, In step (2), the theoretical mass fraction of 1,3-cyclohexanedione in the hydrogenated feed solution is 18-34 wt%.

10. The method as described in claim 1, characterized in that, In step (1), the pressure inside the reactor is evacuated to -0.08 to -0.12 MPa, and nitrogen is introduced to the reactor to a pressure of 0.8 to 1.2 MPa. This process is repeated 2 to 4 times. Then, hydrogen is introduced to the reactor to a pressure of 0.5 to 1.5 MPa. Preferably, when the pressure inside the reactor drops to 0.1 to 0.3 MPa, hydrogen is introduced again to adjust the pressure inside the reactor to 0.5 to 1.5 MPa. This operation is repeated until the pressure inside the reactor no longer decreases. Preferably, if the pressure inside the reactor does not decrease within 10 to 20 minutes, the reaction is continued at a constant temperature for 0.5 to 5 hours.