Method for industrially and continuously producing 2, 2, 4, 4-tetramethyl-1, 3-cyclobutanediol

Abstract

The invention relates to a method for industrially and continuously producing 2, 2, 4, 4-tetramethyl-1, 3-cyclobutanediol, and belongs to the technical field of organic synthesis. The method for industrially and continuously producing 2, 2, 4, 4-tetramethyl-1, 3-cyclobutanediol comprises the following steps: A, mixing isobutyric acid, a chlorinating agent and a solvent, and carrying out continuous chlorination reaction to obtain isobutyryl chloride; b, mixing the isobutyryl chloride with a dechlorinating agent and a solvent to carry out dehydrochlorination reaction and dimerization reaction to obtain 2, 2, 4, 4-tetramethyl-1, 3-cyclobutanedione; c.2, 2, 2, 4, 4-tetramethyl-1, 3-cyclobutanedione is subjected to continuous hydrogenation reduction, and 2, 2, 4, 4-tetramethyl-1, 3-cyclobutanediol is obtained through preparation of 2, 2, 4, 4-tetramethyl-1, 3-cyclobutanediol; the continuous chlorination reaction in the step A is sequentially controlled to be 30-40 DEG C, stays for 0.5-2 hours, is controlled to be 50-65 DEG C and stays for 0.5-2 hours, and is controlled to be 80-100 DEG C and stays for 1-3 hours. The method provided by the invention realizes industrial large-scale continuous production of 2, 2, 4, 4-tetramethyl-1, 3-cyclobutanediol.

Description

Technical Field

[0001] The invention relates to a method for industrially continuously producing 2,2,4,4-tetramethyl-1,3-cyclobutanediol, and belongs to the technical field of organic synthesis. Background Art

[0002] 2,2,4,4-Tetramethyl-1,3-cyclobutanediol (CBDO), CBDO can significantly enhance the glass transition temperature of polyester, improve weather resistance and transparency, and is an ideal raw material to replace polycarbonate. CBDO is used as a hard segment monomer for producing high-temperature polyurethane.

[0003] According to literature reports, CBDO can be used to produce BPA-free epoxy resins, which can replace traditional epoxy resins in the coating of food packaging. The United States has already started using it, but it is not available in China yet. As people pay more and more attention to food safety and health, the domestic market size is expected to grow gradually. CBDO can also produce polyester diols for high-temperature and sun-resistant powder coatings. Overall, the CBDO market size cannot meet domestic demand.

[0004] The current process for industrial preparation of CBDO is to first prepare dimethyl ketone (DMK) and then dimerize it into 2,2,4,4-tetramethyl-1,3-cyclobutanedione (TMCK). There are two routes for preparing TMCK.

[0005] One is to use isobutyric anhydride as raw material and crack it at high temperature (above 500°C) to remove water molecules to generate DMK dimerized into TMCK. This is represented by the technology of US Patents US5169996 / US5258556. This method has long been industrialized in Eastman, USA.

[0006]

[0007] In China, Zhejiang University and Wanhua Chemical are the representatives, and there are a large number of patent reports on this route.

[0008] However, due to the difficulty of technical barriers, there has been no industrial demonstration device. The advantage of this technical route is that the gas phase method is easy to achieve continuous production and scale, but the disadvantages are high temperature energy consumption, high technical barriers, and dangerous high temperature cracking production process.

[0009] The second method is to use isobutyryl chloride at medium to low temperature (30-140°C) with triethylamine as a dechlorinating agent to dehydrochlorinate DMK to dimerize it into TMCK. This technology is represented by German BASF patent US6559343. At present, there are many patents published by domestic companies on this method, such as CN112457170, which is nothing more than further improvement on the basis of US6559343.

[0010]

[0011] The advantages of this route are low energy consumption and relatively safe production process. The disadvantages are that the liquid-solid phase reaction is not easy to be continuous and cannot be scaled up, and a large amount of triethylamine hydrochloric acid needs to be recovered, resulting in high production costs. At present, this technical route only stays in the intermittent reaction stage on the eve of industrialization, and there is no industrialization report of continuous process.

[0012] In summary, these are the technical conditions and reasons why CBDO has not been industrialized and has not been able to replace imports in the past decade.

[0013] The process of continuously producing isobutyryl chloride by reacting isobutyric acid with a chlorinating agent is still at the laboratory stage and cannot be realized in industrial large-scale continuous production.

[0014] The catalyst for preparing CBDO by hydrogenation of TMCB is generally a precious metal ruthenium catalyst, which is expensive and easily poisoned.

[0015] CN110124674A discloses a catalyst and a preparation method thereof, as well as an apparatus and method for preparing 2,2,4,4-tetramethyl-1,3-cyclobutanediol. The catalyst comprises a main active metal element, a metalloid element, a carrier and an optional auxiliary active metal element, wherein the main active metal element is one or more of Fe, Co and Ni, the metalloid element is B and / or P, and the auxiliary active metal element is one or more of Co, Ru, Pd, Rh, Ir and Pt; based on the total weight of the catalyst, the content of the main active metal element is 1-70% by weight. The catalyst, the apparatus and the preparation method of the present invention can realize the efficient conversion of ketones, improve the cis-trans isomerization molar ratio of the 2,2,4,4-tetramethyl-1,3-cyclobutanediol product, and reduce the wear and consumption of the catalyst. However, its cost is high and the conversion rate needs to be further improved. Summary of the invention

[0016] The first object of the present invention is to provide a method for industrially and continuously producing 2,2,4,4-tetramethyl-1,3-cyclobutanediol.

[0017] To achieve the first object of the present invention, the method for industrial continuous production of 2,2,4,4-tetramethyl-1,3-cyclobutanediol comprises:

[0018] A. mixing isobutyric acid, a chlorinating agent and a solvent and performing a continuous chlorination reaction to obtain isobutyryl chloride;

[0019] B. isobutyryl chloride is then mixed with a dechlorinating agent and a solvent to undergo a dehydrochlorination reaction and a dimerization reaction to obtain 2,2,4,4-tetramethyl-1,3-cyclobutanedione (TMCK / TMCB);

[0020] C. 2,2,4,4-tetramethyl-1,3-cyclobutanediol (CBDO) was prepared by continuous hydrogenation reduction of 2,2,4,4-tetramethyl-1,3-cyclobutanedione;

[0021] The continuous chlorination reaction in step A is successively controlled at 30°C-40°C, staying for 0.5-2h, controlled at 50-65°C, staying for 0.5-2h, and controlled at 80-100°C, staying for 1-3h.

[0022] The solvent in step A is at least one of cyclohexane, dipropyl ether, tert-butyl ether, toluene and xylene; the solvent in step B is at least one of toluene, xylene, chloroform, dichloromethane, dichloroethane, acetonitrile, DMF, DEF, NMP, DMI, DMSO, DMPU, dipropyl ether, methyl tert-butyl ether, ethyl tert-butyl ether, ethyl acetate, butyl acetate and butyl propionate, preferably dipropyl ether.

[0023] In a specific embodiment, the chlorinating agent is at least one of: fixed light, thionyl chloride, and phosphorus oxychloride; preferably fixed light.

[0024] In a specific embodiment, the dechlorinating agent is a tertiary amine; preferably at least one of trimethylamine, triethylamine, tripropylamine, dimethylethylamine, diethylmethylamine, dimethylbenzylamine and diethylbenzylamine.

[0025] In a specific embodiment, the pressure of the dehydrochlorination reaction in step B is 0.1-0.5 MPa, and the dehydrochlorination reaction is controlled at 20-40° C. for 1-2 hours.

[0026] In a specific embodiment, the pressure of the dimerization reaction in step B is 0.01-0.1 MPa, and the dimerization reaction is sequentially controlled to stay at 40-70°C for 1-2 hours and at 90-120°C for 1-2 hours.

[0027] In a specific embodiment, the pressure of the continuous hydrogenation reduction in step C is 3-6 MPa, the temperature of the continuous hydrogenation reduction is controlled at 70-300°C, and the reaction space velocity of the continuous hydrogenation reduction is controlled at 0.1-1 h -1 Preferably, the pressure of the continuous hydrogenation reduction in step C is controlled at 4 to 5 MPa, the temperature is controlled at 90 to 200 ° C, and the reaction space velocity is controlled at 0.3 to 0.5 h -1 .

[0028] In a specific embodiment, the catalyst for the continuous hydrogenation reduction in step C is Ni-Sn / TiO2; the nickel content of the catalyst is 20% to 50%, preferably 21 to 25%.

[0029] In one specific embodiment, the method for preparing the catalyst comprises:

[0030] A NiCl2 aqueous solution, an SnCl2 ethanol / 2-methoxyethanol solution, and TiO2 are mixed to obtain a mixture, the mixture is heated to 40-50°C and stirred for 8-12 hours, the pH is adjusted to 11-12, and then the mixture is sealed and hydrothermally reacted at 150°C for 24 hours to generate a black precipitate, the temperature is reduced, filtered, washed with distilled water, and vacuum dried to obtain a catalyst precursor, wherein the molar ratio of ethanol to 2-methoxyethanol in the ethanol / 2-methoxyethanol is 2:1;

[0031] The catalyst precursor is pressed into tablets and then subjected to hydrogenation reduction at a temperature of 280 to 320° C., a hydrogen-nitrogen ratio of 1:9, and the reduction is performed for 2 to 4 hours.

[0032] The second object of the present invention is to provide a continuous hydrogenation reduction catalyst for the above-mentioned industrial continuous production of 2,2,4,4-tetramethyl-1,3-cyclobutanediol, wherein the continuous hydrogenation reduction catalyst is Ni-Sn / TiO2; the nickel content in the catalyst is 21% to 50%, preferably 21 to 25%.

[0033] In one specific embodiment, the method for preparing the catalyst comprises:

[0034] A NiCl2 aqueous solution, an SnCl2 ethanol / 2-methoxyethanol solution, and TiO2 are mixed to obtain a mixture, the mixture is heated to 40-50°C and stirred for 8-12 hours, the pH is adjusted to 11-12, and then the mixture is sealed and hydrothermally reacted at 150°C for 24 hours to generate a black precipitate, the temperature is reduced, filtered, washed with distilled water, and vacuum dried to obtain a catalyst precursor, wherein the molar ratio of ethanol to 2-methoxyethanol in the ethanol / 2-methoxyethanol is 2:1;

[0035] The catalyst precursor is pressed into tablets and then subjected to hydrogenation reduction at a temperature of 280 to 320° C., a hydrogen-nitrogen ratio of 1:9, and the reduction is performed for 2 to 4 hours.

[0036] The catalyst precursor is pressed into tablets and can be reduced online in the production line or before loading.

[0037] Beneficial effects:

[0038] 1. The present invention starts from basic raw materials and realizes industrial large-scale continuous production of 2,2,4,4-tetramethyl-1,3-cyclobutanediol. The reaction raw materials are widely available, and the reaction process is safe, low in energy consumption, and environmentally friendly. The process is continuous, large-scale, and low in cost. It has the competitiveness and risk resistance in the industry and is worthy of large-scale promotion and application.

[0039] 2. The present invention uses a newly developed non-precious metal catalyst to reduce costs, and the production process can be continuously operated at low cost, which is significantly improved.

[0040] 3. The catalyst of the present invention has high catalytic efficiency and high conversion rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 Flow chart of the process equipment for continuous preparation of isobutyryl chloride;

[0042] Figure 2 Flow chart of continuous preparation of TMCB process equipment;

[0043] Figure 3 Flow chart of the continuous preparation of CBDO process equipment. DETAILED DESCRIPTION

[0044] To achieve the first object of the present invention, the method for industrial continuous production of 2,2,4,4-tetramethyl-1,3-cyclobutanediol comprises:

[0045] A. mixing isobutyric acid, a chlorinating agent and a solvent and performing a continuous chlorination reaction to obtain isobutyryl chloride;

[0046] B. isobutyryl chloride is then mixed with a dechlorinating agent and a solvent to undergo a dehydrochlorination reaction and a dimerization reaction to obtain 2,2,4,4-tetramethyl-1,3-cyclobutanedione (TMCK / TMCB);

[0047] C. 2,2,4,4-tetramethyl-1,3-cyclobutanediol (CBDO) was prepared by continuous hydrogenation reduction of 2,2,4,4-tetramethyl-1,3-cyclobutanedione;

[0048] The continuous chlorination reaction in step A is successively controlled at 30°C-40°C, staying for 0.5-2h, controlled at 50-65°C, staying for 0.5-2h, and controlled at 80-100°C, staying for 1-3h.

[0049] The solvent in step A is at least one of cyclohexane, dipropyl ether, tert-butyl ether, toluene and xylene; the solvent in step B is at least one of toluene, xylene, chloroform, dichloromethane, dichloroethane, acetonitrile, DMF, DEF, NMP, DMI, DMSO, DMPU, dipropyl ether, methyl tert-butyl ether, ethyl tert-butyl ether, ethyl acetate, butyl acetate and butyl propionate, preferably dipropyl ether.

[0050] In a specific embodiment, the chlorinating agent is at least one of: fixed light, thionyl chloride, and phosphorus oxychloride; preferably fixed light.

[0051] In a specific embodiment, the dechlorinating agent is a tertiary amine; preferably at least one of trimethylamine, triethylamine, tripropylamine, dimethylethylamine, diethylmethylamine, dimethylbenzylamine and diethylbenzylamine.

[0052] The tertiary amine may be an aliphatic trialkylamine or an aromatic tertiary amine.

[0053] In a specific embodiment, the reaction molar ratio of isobutyric acid to solid light is controlled at 1:0.33-1, the weight ratio of solvent to solid light is controlled at 1:5-6, and the reaction temperature.

[0054] In a specific embodiment, in the dehydrochlorination reaction in step B, the molar ratio of isobutyryl chloride to tertiary amine is controlled at 1:1-3, and the weight ratio of isobutyryl chloride to solvent is controlled at 1:1-5.

[0055] In a specific embodiment, the pressure of the dehydrochlorination reaction in step B is 0.1-0.5 MPa, and the dehydrochlorination reaction is controlled at 20-40° C. for 1-2 hours.

[0056] In a specific embodiment, the pressure of the dimerization reaction in step B is 0.01-0.1 MPa, and the dimerization reaction is sequentially controlled to stay at 40-70°C for 1-2 hours and at 90-120°C for 1-2 hours.

[0057] In a specific embodiment, the pressure of the continuous hydrogenation reduction in step C is 3-6 MPa, the temperature of the continuous hydrogenation reduction is controlled at 70-300°C, and the reaction space velocity of the continuous hydrogenation reduction is controlled at 0.1-1 h -1 Preferably, the pressure of the continuous hydrogenation reduction in step C is controlled at 4 to 5 MPa, the temperature is controlled at 90 to 200 ° C, and the reaction space velocity is controlled at 0.3 to 0.5 h -1 .

[0058] In a specific embodiment, the mass percentage concentration of the material for continuous hydrogenation in step C is controlled at 20-50%, preferably at 30%.

[0059] In one specific embodiment, the method for industrial continuous production of 2,2,4,4-tetramethyl-1,3-cyclobutanediol comprises:

[0060] 1) Continuous preparation process of isobutyryl chloride

[0061] The solid light is pre-mixed with the solvent and then is continuously pumped into three series-connected reactors with isobutyric acid for continuous reaction. After the chlorination reaction is completed, the mixture is sent to a continuous distillation tower for separation and purification.

[0062] 2) Preparation of DMK by dehydrochlorination reaction and preparation of TMCB by dimerization: isobutyryl chloride, dechlorinating agent trialkylamine (tertiary amine), and solvent are pumped into a continuous process of multiple reactors in series, and the trialkylamine (tertiary amine) hydrochloride solid is continuously separated from the last reactor, and DMK flows into the next process as a liquid phase with the solvent for dimerization; the liquid phase containing DMK is continuously added to two sets of dimerization towers in series, and a certain temperature and residence time are maintained until the dimerization reaction is complete, and the TMCB solution is sent to the next process for hydrogenation;

[0063] 3) Preparation of CBDO by continuous hydrogenation process

[0064] Liquid phase fixed bed continuous hydrogenation process for preparing CBDO.

[0065] In a specific embodiment, the catalyst for the continuous hydrogenation reduction in step C is Ni-Sn / TiO2; the nickel content in the catalyst is 20% to 50%, preferably 21 to 25%;

[0066] In one specific embodiment, the method for preparing the catalyst comprises:

[0067] A NiCl2 aqueous solution, an SnCl2 ethanol / 2-methoxyethanol solution, and TiO2 are mixed to obtain a mixture, the mixture is heated to 40-50°C and stirred for 8-12 hours, the pH is adjusted to 11-12, and then the mixture is sealed and hydrothermally reacted at 150°C for 24 hours to generate a black precipitate, the temperature is reduced, filtered, washed with distilled water, and vacuum dried to obtain a catalyst precursor, wherein the molar ratio of ethanol to 2-methoxyethanol in the ethanol / 2-methoxyethanol is 2:1;

[0068] The catalyst precursor is pressed into tablets and then subjected to hydrogenation reduction at a temperature of 280 to 320° C., a hydrogen-nitrogen ratio of 1:9, and the reduction is performed for 2 to 4 hours.

[0069] The second object of the present invention is to provide a continuous hydrogenation reduction catalyst for the above-mentioned industrial continuous production of 2,2,4,4-tetramethyl-1,3-cyclobutanediol, wherein the continuous hydrogenation reduction catalyst is Ni-Sn / TiO2; the nickel content in the catalyst is 20% to 50%.

[0070] In one specific embodiment, the method for preparing the catalyst comprises:

[0071] An aqueous solution of NiCl2, an ethanol / 2-methoxyethanol solution of SnCl2, and TiO2 are mixed to obtain a mixture, the mixture is heated to 40-50°C and stirred for 8-12 hours, the pH is adjusted to 11-12, and then the mixture is sealed and hydrothermally reacted at 150°C for 24 hours to generate a black precipitate, the temperature is reduced, the precipitate is filtered, washed with distilled water, and vacuum dried to obtain a catalyst precursor, wherein the molar ratio of ethanol to 2-methoxyethanol in the ethanol / 2-methoxyethanol is 2:1;

[0072] The catalyst precursor is pressed into tablets and then subjected to hydrogenation reduction at a temperature of 280 to 320° C., a hydrogen-nitrogen ratio of 1:9, and the reduction is performed for 2 to 4 hours.

[0073] The specific implementation modes of the present invention are further described below in conjunction with embodiments, but the present invention is not limited to the scope of the embodiments.

[0074] Example 1

[0075] Preparation of Isobutyryl Chloride by Continuous Chlorination

[0076] 1) If Figure 1 As shown, isobutyric acid is fed at 88.15 kg / h and 15% concentration solid light is fed at 660 kg / h. Solid light is dissolved in solvent cyclohexane in advance and continuously added to reactor R1 through pumps P1 and P2 respectively. The materials flow in continuously in sequence. The temperature in R1 is controlled at 30-40°C, the temperature in R2 is controlled at 50-60°C, and the temperature in R3 is controlled at 80-100°C. The pressure in R1, R2, and R3 is normal pressure (gauge pressure is 0 bar). The residence time of the materials in R1, R2, and R3 is controlled to be 1 h, 1 h, and 2 h, respectively. The conversion rate of isobutyric acid is 99.5%, and the selectivity is 98%.

[0077] 2) The material flows out from R3 and is added to the storage tank V1, and is continuously input into the distillation tower system by pump P3 for distillation purification and solvent recovery (applied).

[0078] 3) The quality index composition of the distilled fine isobutyryl chloride is shown in Table 1.

[0079] Table 1 Isobutyryl chloride mass preparation composition produced in Example 1

[0080] project Content (%) GC content 99.5 Appearance Colorless liquid Solvent residue 100ppm Chlorine content 20ppm .

[0081] Comparative Example 1

[0082] Preparation of Isobutyryl Chloride by Batch Method

[0083] 88.15 kg of isobutyric acid was added to a 2 cubic reactor, and then 660 kg of 15% solid light was added to the reactor, and isobutyryl chloride was added dropwise at a rate of 30 kg / h (the purpose of adding isobutyryl chloride was to control the temperature and prevent the increase of reaction by-products). The temperature was kept within 50-70°C during the process, and the reaction time was 10 hours. The conversion rate of isobutyric acid was 95.5%, and the selectivity was 88%.

[0084] By comparison, it was found that the continuous preparation of isobutyryl chloride consumes less energy, takes 6 hours less time than the intermittent method, and has much better reaction conversion rate and selectivity.

[0085] Example 2

[0086] Preparation of TMCB by Continuous Dechlorination Dimerization

[0087] 1) If Figure 2 As shown, 53.3 kg / h of isobutyryl chloride, 130 kg / h of dipropyl ether and 45 kg / h of trimethylamine are continuously fed into the reactor R4 by pumps P4, P5 and P6 respectively, and the materials flow into R4, R5 and R6 in sequence (the pressure of R4, R5 and R6 is controlled by the pressure of the reaction to be 0.01-0.3 MPa), the temperature in R4 is controlled to be 30-40°C, the temperature in R5 is controlled to be 50-70°C, the temperature in R6 is controlled to be 90-120°C, and the residence times in R4, R5 and R6 are 2h, 2h and 2h respectively.

[0088] 2) The material flows out from R6 and enters the cyclone Q1 for preliminary solid-liquid separation, and then further passes through the centrifuge for thorough liquid-solid separation. The solid phase is trimethylamine hydrochloride, and the liquid phase is a solution containing TMCB, which continuously enters the storage tank V2.

[0089] 3) Dry the solid phase salt. The liquid phase is subjected to gas chromatography analysis, and the quality indicators are shown in Table 2.

[0090] Table 2 TMCB quality index composition of Example 2

[0091] project Content (wt.%) TMCB content 16.1% GC Solvents 75.9% GC Appearance Light yellow liquid Solid salt content 0.3％ Other impurities 8% GC .

[0092] Comparative Example 2

[0093] Preparation of TMCB by Batch Dimerization

[0094] 53.3 kg of isobutyryl chloride and 130 kg of dipropyl ether were added to the reactor. 32.5 kg of trimethylamine was added with a pump under stirring. The pump flow rate was controlled based on the kettle temperature not exceeding 50°C. After 6 h, 10 h, 20 h, 30 h, and 40 h, 500 g of samples were taken for filtration and concentration for analysis. The data obtained were as follows:

[0095] 6h, corresponding to TMCB content 3%

[0096] 10h, corresponding to TMCB content 5%

[0097] 20h, corresponding to TMCB content 8%

[0098] 30h, corresponding to TMCB content 10%

[0099] 40h, corresponding to TMCB content 12%

[0100] The temperature in the kettle was 69°C (reflux temperature of dipropyl ether), and the sampling data analysis was as follows:

[0101] 6h, corresponding to TMCB content 5%

[0102] 10h, corresponding to TMCB content 4%

[0103] 20h, corresponding to TMCB content 3%

[0104] 30h, corresponding to TMCB content 2%

[0105] 40h, corresponding to TMCB content 1%

[0106] By comparison, it is found that only when the temperature of the batch reaction is controlled at 50°C can the TMCB yield be relatively good, but the highest content cannot reach the yield of the continuous reaction. The batch reaction temperature is too high (reflux temperature), and the TMCB yield is too low to produce TMCB. Disadvantages of the batch method: The reaction time is more than 40 hours, while the continuous reaction time is only 6 hours, and the yield exceeds that of the batch reaction.

[0107] Example 3

[0108] Continuous hydrogenation to produce CBDO

[0109] 1) If Figure 3 As shown, the crude TMCB of V2, with a material concentration of 30% wt, is pumped into the bottom of the fixed bed reactor Q2 at 1 kg / h by pump P7. The reactor is filled with 2 L of the catalyst prepared in Example 4. The bed temperature is controlled at 180° C. The reactor pressure is 5 MPa. The material is discharged from the bottom of the gas-liquid separator V3. The hydrogen is circulated by compressor Q3. The TMCB conversion rate is above 98%, the selectivity is above 95%, and the liquid reaction space velocity in this example is 0.5 h -1 .

[0110] 2) The material discharged from V3 is collected and sent to the thin film evaporator Q4 to continuously remove the solvent and low boiling point products. The bottom material is sent to the continuous concentration crystallizer Q5 to obtain the crude CBDO, which is purified by the thin film evaporation distillation device Q6. The material is melted and discharged from the collection tank, and a white solid is obtained after solidification.

[0111] 3) The content index analysis of the prepared CBDO is shown in Table 3.

[0112] Table 3 Example 3 CBDO quality index composition

[0113] project Content (wt.%) Appearance White solid Chroma 20 DMF insoluble matter 0.1 content 99.8% GC Melting point 125.2～125.3℃ .

[0114] Comparative Example 3

[0115] Other conditions remain unchanged, and Ni-Co-Al2O3 (purchased from a catalyst factory in Liaoning, with a nickel content of 40%, a cobalt content of 15%, and the remainder being alumina) is used. The specific implementation is as follows:

[0116] The crude TMCB from V2, with a material concentration of 30% wt, is pumped into the bottom of the fixed bed reactor Q2 at a rate of 1 kg / h by pump P7. The reactor is loaded with 2 L of catalyst (purchased from outside), the bed temperature is controlled at 180°C, the reactor pressure is 5 MPa, the material is discharged from the bottom of the gas-liquid separator V3, and the hydrogen is circulated by compressor Q3. The TMCB conversion rate is above 50%, the selectivity is above 40%, and the liquid reaction space velocity in this example is 0.5 h -1 .

[0117] The material discharged from V3 is collected and sent to the thin film evaporator Q4 to continuously remove the solvent and low boiling point substances. The bottom material is sent to the continuous concentration crystallizer Q5 to obtain the crude CBDO, which is purified by the thin film evaporation distillation device Q6. The material is melted and discharged from the collection tank and solidified into a white solid.

[0118] By comparison, it is found that the catalyst prepared by the present invention has good activity, and the conversion rate and selectivity are far higher than the commercially available catalyst. According to the actual production process, it is found that if the conversion rate does not reach 95% and the selectivity does not reach more than 80%, CBDO cannot be produced at low cost, that is, the outsourced catalyst fails in industrial implementation.

[0119] Example 4

[0120] Preparation of hydrogenation catalyst

[0121] 1) Dissolve NiCl2·6H2O in deionized water (denoted as solution A), and dissolve SnCl2·2H2O in ethanol / 2-methoxyethanol (the molar ratio of ethanol to 2-methoxyethanol is 2:1) (denoted as solution B), mix TiO2, solution A and solution B at room temperature, and the molar mass ratio of NiCl2·6H2O, SnCl2·2H2O and TiO2 is 0.72 mol:0.48 mol:100 g; the temperature is then increased to 50°C, and stirring is continued for 12 hours, and a NaOH aqueous solution is added dropwise to the mixture to adjust the pH to 12, and then the mixture is placed in a sealed Teflon autoclave for hydrothermal reaction and reacted at 150°C for 24 hours. The generated black precipitate is cooled, filtered, washed with distilled water, and then dried under vacuum to obtain a catalyst precursor.

[0122] 2) The obtained powder catalyst precursor was loaded into a tablet press at 100 MPA and punched into 2-3 mm columns, and then transferred to a reduction furnace for hydrogenation reduction at a temperature of 320° C., a hydrogen-nitrogen ratio of 1:9, and reduced for 4 hours. After cooling, it was set aside.

[0123] 3) The prepared nickel-based catalyst was analyzed and its composition is shown in Table 4.

[0124] Table 4 Catalyst composition of Example 4

[0125] project Content (wt.%) Appearance Gray black particles Dimensions 2-3mm Nickel content 21.2％ Titanium oxide content 50.2％ .

Claims

1. A method for industrial continuous production of 2,2,4,4-tetramethyl-1,3-cyclobutanediol, characterized in that: The method comprises: A. mixing isobutyric acid, a chlorinating agent and a solvent and performing a continuous chlorination reaction to obtain isobutyryl chloride; B. isobutyryl chloride is then mixed with a dechlorinating agent and a solvent to undergo a dehydrochlorination reaction and a dimerization reaction to obtain 2,2,4,4-tetramethyl-1,3-cyclobutanedione; C. 2,2,4,4-tetramethyl-1,3-cyclobutanediol was prepared by continuous hydrogenation reduction of 2,2,4,4-tetramethyl-1,3-cyclobutanediol; The continuous chlorination reaction in step A is successively controlled at 30°C-40°C, staying for 0.5-2h, controlled at 50-65°C, staying for 0.5-2h, and controlled at 80-100°C, staying for 1-3h.

2. The method for industrial continuous production of 2,2,4,4-tetramethyl-1,3-cyclobutanediol according to claim 1, characterized in that: The chlorinating agent is at least one of: light fixation, thionyl chloride, and phosphorus oxychloride; preferably light fixation.

3. The method for industrial continuous production of 2,2,4,4-tetramethyl-1,3-cyclobutanediol according to claim 1 or 2, characterized in that: The dechlorinating agent is a tertiary amine; preferably at least one of trimethylamine, triethylamine, tripropylamine, dimethylethylamine, diethylmethylamine, dimethylbenzylamine and diethylbenzylamine.

4. The method for industrial continuous production of 2,2,4,4-tetramethyl-1,3-cyclobutanediol according to claim 1 or 2, characterized in that: The pressure of the dehydrochlorination reaction in step B is 0.1-0.5 MPa, and the dehydrochlorination reaction is controlled at 20-40°C for 1-2 hours; the pressure of the dimerization reaction in step B is 0.01-0.1 MPa, and the dimerization reaction is controlled at 40-70°C for 1-2 hours and 90-120°C for 1-2 hours.

5. The method for industrial continuous production of 2,2,4,4-tetramethyl-1,3-cyclobutanediol according to claim 1 or 2, characterized in that: The solvent in step A is at least one of cyclohexane, dipropyl ether, tert-butyl ether, toluene and xylene; the solvent in step B is at least one of toluene, xylene, chloroform, dichloromethane, dichloroethane, acetonitrile, DMF, DEF, NMP, DMI, DMSO, DMPU, dipropyl ether, methyl tert-butyl ether, ethyl tert-butyl ether, ethyl acetate, butyl acetate and butyl propionate, preferably dipropyl ether.

6. The method for industrial continuous production of 2,2,4,4-tetramethyl-1,3-cyclobutanediol according to claim 1 or 2, characterized in that: The pressure of the continuous hydrogenation reduction in step C is 3-6 MPa, the temperature of the continuous hydrogenation reduction is controlled at 70-300°C, and the reaction space velocity of the continuous hydrogenation reduction is controlled at 0.1-1 h -1 Preferably, the pressure of the continuous hydrogenation reduction in step C is controlled at 4 to 5 MPa, the temperature is controlled at 90 to 200 ° C, and the reaction space velocity is controlled at 0.3 to 0.5 h -1 .

7. The method for industrial continuous production of 2,2,4,4-tetramethyl-1,3-cyclobutanediol according to claim 6, characterized in that: The catalyst for the continuous hydrogenation reduction in step C is Ni-Sn / TiO2; the nickel content in the catalyst is 20% to 50%, preferably 21 to 25%.

8. The method for industrial continuous production of 2,2,4,4-tetramethyl-1,3-cyclobutanediol according to claim 7, characterized in that: The preparation method of the catalyst comprises: A NiCl2 aqueous solution, an SnCl2 ethanol / 2-methoxyethanol solution, and TiO2 are mixed to obtain a mixture, the mixture is heated to 40-50°C and stirred for 8-12 hours, the pH is adjusted to 11-12, and then the mixture is sealed and hydrothermally reacted at 150°C for 24 hours to generate a black precipitate, the temperature is reduced, filtered, washed with distilled water, and vacuum dried to obtain a catalyst precursor, wherein the molar ratio of ethanol to 2-methoxyethanol in the ethanol / 2-methoxyethanol is 2:1; The catalyst precursor is pressed into tablets and then subjected to hydrogenation reduction at a temperature of 280 to 320° C., a hydrogen-nitrogen ratio of 1:9, and the reduction is performed for 2 to 4 hours.

9. A continuous hydrogenation reduction catalyst for industrial continuous production of 2,2,4,4-tetramethyl-1,3-cyclobutanediol, characterized in that: The catalyst for continuous hydrogenation reduction is Ni-Sn / TiO2; the nickel content of the catalyst is 20% to 50%, preferably 21 to 25%.

10. The continuous hydrogenation reduction catalyst for industrial continuous production of 2,2,4,4-tetramethyl-1,3-cyclobutanediol according to claim 9, characterized in that: The preparation method of the catalyst comprises: A NiCl2 aqueous solution, an SnCl2 ethanol / 2-methoxyethanol solution, and TiO2 are mixed to obtain a mixture, the mixture is heated to 40-50°C and stirred for 8-12 hours, the pH is adjusted to 11-12, and then the mixture is sealed and hydrothermally reacted at 150°C for 24 hours to generate a black precipitate, the temperature is reduced, filtered, washed with distilled water, and vacuum dried to obtain a catalyst precursor, wherein the molar ratio of ethanol to 2-methoxyethanol in the ethanol / 2-methoxyethanol is 2:1; The catalyst precursor is pressed into tablets and then subjected to hydrogenation reduction at a temperature of 280 to 320° C., a hydrogen-nitrogen ratio of 1:9, and the reduction is performed for 2 to 4 hours.

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