Process method for preparing DMCD from DMT by using nickel-based catalyst

Abstract

The invention discloses a process method for preparing DMCD from DMT by using a nickel-based catalyst, and belongs to the technical field of industrial catalysis, and the process method comprises the following steps: S1, preparing the nickel-based catalyst: taking a carbonate solution, a carrier solution and an active metal salt solution as raw materials, mixing and reacting, adding an alkali liquor to adjust the pH to be alkaline until the color of the turbid liquid is changed from blackish green to brown, and filtering to obtain the nickel-based catalyst; standing, centrifugally drying, roasting, and carrying out reduction reaction to obtain the catalyst. S2, filling the fixed bed device with a catalyst; and S3, feeding the dissolved DMT and hydrogen into a fixed bed device according to a certain flow rate, starting a hydrogenation reaction, and continuously producing DMCD. According to the present invention, the DMT is dissolved by using the organic solvent and then is fed on the fixed bed, the continuous production can be achieved by using the fixed bed device, the DMT hydrogenation conversion rate is high, the catalyst can be repeatedly used, the reaction pressure is limited to be low pressure (less than or equal to 1 MPa) in the method, the safety is provided, and the high practical value and the industrial application prospect are provided.

Description

Technical Field

[0001] The present invention relates to the field of industrial catalysis technology, and in particular to a process for preparing DMCD from DMT using a nickel-based catalyst. Background Art

[0002] Dimethyl 1,4-cyclohexanedicarboxylate (DMCD) is a methyl ester compound and also a carbonyl compound, which is an important organic chemical raw material and pharmaceutical intermediate. DMCD has the basic properties of lipid organic compounds and has many unsaturated chemical bonds, and can undergo addition reactions with chemical reagents such as hydrogen, halogen atoms, and diene compounds. It has a wide range of applications in the chemical material and synthesis fields such as the modification of polymers, the production of lubricants and hydraulic fluids, the production of cosmetics and personal care products, and the production of environmental protection materials and resin coatings. DMCD can be hydrogenated to obtain the saturated or unsaturated polyester monomer 1,4-cyclohexanedimethanol (CHDM) with excellent properties. CHDM is the raw material for synthesizing various polyester materials with excellent properties, light-colored polyurethane coatings, various fragrances, dyes, and surfactants, as well as the intermediate for preparing various pharmaceuticals such as various antibiotics, anti-cancer drugs, hormonal drugs, and cardiovascular drugs. As an important intermediate for the preparation of CHDM, the demand for DMCD in China is also increasing rapidly.

[0003] In the prior art, the liquid-phase catalytic hydrogenation method has been industrialized. Using DMT as a raw material, DMCD is produced through two-step hydrogenation reactions. Some patents in the United States have proposed the preparation of DMCD, but the pressures required for the reactions are all higher than 10 MPa. Such high pressures not only pose a threat to production safety but also place high requirements on production equipment, which increases the operating costs of enterprises. In order to reduce the pressure required for the reaction, some invention patents in China have disclosed a catalyst for preparing DMCD from DMT. The main active component of this catalyst is palladium, and the promoter consists of two metal elements. The two metal elements of the first promoter and the second promoter come from Group IIA and Group VIII respectively. Alumina is used as the carrier of the catalyst, and the reaction pressure is reduced to 6 MPa, and the reaction temperature is 150 - 350 °C. The invention patent with the publication number CN102580732A has disclosed a catalyst for catalytically hydrogenating DMT in one step to prepare CHDM and its preparation method. The three metal active components of ruthenium, platinum, and tin are loaded on the carrier Al2O3 using the co-impregnation method, and the intermittent synthesis of DMT to CHDM is realized through two-step hydrogenation reactions in a reaction kettle: heating and stirring are started at a hydrogen pressure of 3 MPa until the reaction temperature reaches 180 °C, and then the reaction pressure is adjusted to 6 MPa. After two hours, the temperature is raised to 260 °C, and the pressure is adjusted to 8.5 MPa. The reaction is carried out under these conditions for 8 h, and then the reaction is stopped. The conversion rate of DMT > 97.1%, and the selectivity of the target product CHDM is 53.2% - 75.1%. Although the reaction pressures set in the above technical solutions in the DMT preparation process have been reduced compared to the pressure condition of 10 MPa, this pressure is still not the lowest, and they are all improvements to the active components of the catalyst in an intermittent autoclave reactor.

[0004] Therefore, based on the problems of high reaction pressure, expensive catalyst, and inability to carry out continuous production in the above prior art solutions, a process method is proposed to reduce the reaction pressure during the preparation of DMCD from DMT, continuously produce DMCD in a fixed bed, and thereby reduce the cost of DMCD. Summary of the Invention

[0005] The purpose of the present invention is to provide a process method using a nickel-based catalyst for preparing DMCD from DMT to solve the problems in the background technology.

[0006] To achieve the above purpose, the present invention provides a process method using a nickel-based catalyst for preparing DMCD from DMT, including the following steps:

[0007] S1. Prepare the nickel-based catalyst: Using carbonate solution, carrier solution, and active metal salt solution as raw materials, after mixing and reacting, add an alkali solution to adjust the pH to alkaline until the color of the suspension changes from dark green to coffee color. After standing, centrifuge and dry, and obtain the catalyst after calcination and reduction reactions;

[0008] S2. Place the obtained catalyst into a tablet press mold, conduct tablet pressing on a tablet press, then crush the tablet-shaped catalyst with a mortar. After screening, load the catalyst into the middle of the bed layer of a fixed-bed reaction device, fill a small amount of quartz wool under the bed layer, and heat up the fixed-bed device.

[0009] S3. After the temperature of the fixed-bed device rises to the initial reaction temperature, turn on the feed pump, and feed the dissolved DMT and hydrogen into the fixed-bed device together to start the hydrogenation reaction and continuously produce DMCD.

[0010] Preferably, in S1, the carbonate is sodium carbonate, the alkali solution is sodium hydroxide, or the carbonate is ammonium bicarbonate, the alkali solution is ammonia water, and the concentration of the alkali solution is 0.1 - 3 mol / L.

[0011] Preferably, in S1, the carrier is one or more of β-zeolite, USY zeolite, Al-SBA-15, ZSM-5, silica, and alumina; the active metal salt is one or a mixture of two or more of Pd, Ni, Co, Mo, Mn, Cu, Fe, Cr, Zn, and Mg, and the mass ratio of the carrier to the carbonate is 1 - 6:3.

[0012] Preferably, in S1, the temperature during the pH adjustment process is 30 - 100 °C, the calcination temperature is 400 - 800 °C, and the calcination time is 2 - 10 h; the reduction temperature is 300 - 600 °C, and the reduction time is 2 - 6 h.

[0013] Preferably, in S3, the reaction temperature of the fixed-bed device is 200 - 230 °C, and the reaction pressure is 0.6 - 1 MPa.

[0014] Preferably, in S3, the reaction temperature of the fixed-bed device is 200 °C, and the reaction pressure is 1 MPa.

[0015] Preferably, in S3, DMT is dissolved in an organic solvent, the liquid-phase feed flow rate in the fixed-bed device is 0.1 - 0.6 ml / min, and the hydrogen gas flow rate is 5 - 30 ml / min.

[0016] Preferably, in S3, the liquid-phase feed flow rate in the fixed-bed device is 0.25 ml / min, and the hydrogen gas flow rate is 4 ml / min.

[0017] Preferably, in S3, the dissolved DMT is preheated before being pumped, and hydrogen gas is preheated using a vaporizer, and the temperature of the vaporizer is 50 - 100 °C.

[0018] Preferably, in S3, before starting the hydrogenation reaction, a reducing gas is pumped in to pre-reduce the catalyst, and the treatment time is 30 min. The reducing gas is high-purity hydrogen.

[0019] Therefore, the process method of using a nickel-based catalyst of the present invention for preparing DMCD from DMT has the following beneficial effects:

[0020] (1) In the present invention, a method for continuously preparing DMCD by catalytic hydrogenation of DMT in a fixed-bed reaction device is proposed. After dissolving DMT with an organic solvent and feeding it into the fixed bed, the catalyst can be reused repeatedly, and the reaction pressure is low (≤1 MPa), which has high practical value and industrial application prospects.

[0021] (2) The catalyst used in the present invention is a nickel-based catalyst prepared by a simple co-precipitation method. Its reaction conditions are mild, the hydrogenation conversion rate of DMT ≥ 99%, and the catalyst can operate stably for 200 h, solving the problem of harsh existing conditions; moreover, the newly developed catalyst has the advantages of simple preparation, low cost, and easy recovery and reuse.

[0022] (3) The process method protected by the present invention produces less three wastes, has a simple process, and a relatively high product yield, which conforms to the concept of green chemistry and is suitable for industrial production at the same time.

[0023] The technical solution of the present invention will be further described in detail below through examples. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is the GC-MS detection chart of the product of Comparative Example 2 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] The technical solution of the present invention will be further described below through examples.

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention.

[0027] Example 1

[0028] S1. Prepare a nickel-based catalyst:

[0029] Add 74 g of β zeolite and a certain amount of deionized water to a flask, completely dissolve it, and place it in the flask to obtain a carrier solution;

[0030] Then take 53 g of Na2CO3 and prepare an aqueous solution with a concentration of 5 mol / L; take 0.028 g of PdCl2, 50 g of Ni(NO3)2·6H2O, 30 g of Co(NO3)2·6H2O, 10 g of Fe(NO3)2·9H2O, 10 g of (NH4)6Mo7O 24·4H2O, 10 g of Mn(NO3)2·4H2O, 10 g of Zn(NO3)2·6H2O, and 10 g of Cr(NO3)3·9H2O were added to a certain amount of water and stirred and mixed to completely dissolve them, obtaining a mixed metal salt solution; the mixed metal salt solution and an aqueous sodium carbonate solution were simultaneously added to the carrier solution and mixed evenly, and the suspension turned dark green;

[0031] Then, the pH value of the suspension was adjusted to 14 with 1 mol / L sodium hydroxide solution, and it was stirred at a constant temperature of 70 °C for 14 h. The solution changed from a dark green suspension to a coffee color. After standing overnight, it was centrifuged and dried. Finally, it was calcined at 500 °C for 12 h. After the calcination was completed, hydrogen was used as a reducing agent for the reduction reaction. The reduction temperature was controlled at 500 °C, and a nickel-based catalyst was obtained after reacting for 5 h.

[0032] S2. Filling the nickel-based catalyst in a fixed bed: The obtained catalyst was put into a tablet press mold and tableted on a tablet press. The catalyst was pressed into tablets with a certain thickness; then, the tableted catalyst was crushed with a mortar, and particles with a particle size of 30 mesh were screened using a standard metal sieve. After screening, 5.0 g of the catalyst was placed in the middle of the bed layer, and a small amount of quartz wool was filled under the bed layer; when filling the catalyst, pay attention to filling the catalyst evenly and keeping it on the same plane;

[0033] After filling, high-purity hydrogen was pumped in as a reducing gas for pre-reducing the catalyst for 30 min;

[0034] S3. After the pre-reduction treatment was completed, the temperature of the fixed bed device was raised to 300 °C, and at the same time, the feed was preheated; then, the feed pump was started, and DMT dissolved in an organic solvent was fed at a flow rate of 0.25 ml / min, and hydrogen was fed synchronously at a flow rate of 4 mol / min. The reaction temperature was controlled at 300 °C, and the reaction pressure was 1 MPa, and the hydrogenation reaction was started to continuously produce DMCD.

[0035] In the above Example 1, the specific route for synthesizing DMCD by using a nickel-based catalyst to catalyze DMT was as follows:

[0036]

[0037] Example 2

[0038] This example was the same as the steps of Example 1, and the only difference was that the liquid-phase feed flow rate in step S3 was 0.4 ml / min and the hydrogen flow rate was 10 ml / min.

[0039] Comparative Example 1

[0040] This comparative example had the same preparation steps as Example 1, and only the temperature of the reaction bed device in step S3 was adjusted to 180 °C.

[0041] Comparative Example 2

[0042] The preparation steps of this comparative example are the same as those of Example 1, only the temperature of the reaction bed device in step S3 is adjusted to 190 °C.

[0043] Comparative Example 3

[0044] The preparation steps of this comparative example are the same as those of Example 1, only the temperature of the reaction bed device in step S3 is adjusted to 210 °C.

[0045] Comparative Example 4

[0046] The preparation steps of this comparative example are the same as those of Example 1, only the temperature of the reaction bed device in step S3 is adjusted to 220 °C.

[0047] Comparative Example 5

[0048] The preparation steps of this comparative example are the same as those of Example 1, only the reaction pressure of the reaction bed device in step S3 is adjusted to 0.5 MPa.

[0049] Comparative Example 6

[0050] The preparation steps of this comparative example are the same as those of Example 1, only the reaction pressure of the reaction bed device in step S3 is adjusted to 1.5 MPa.

[0051] The products of the above Examples 1, 2 and Comparative Examples 1-6 were detected. After dilution with ethanol and detection by GC-MS, the conversion rate and selectivity were obtained as shown in Table 1 below;

[0052]

[0053] According to Table 1 and in combination with Figure 1 Comparison: In Comparative Example 1 and Comparative Example 2, when the temperature of the fixed bed device is lower than 200 °C, both the conversion rate of DMT and the selectivity of DMCD decrease, and the lower the temperature, the lower the conversion rate of DMT and the selectivity of DMCD; in Comparative Examples 3 and 4, when the temperature is higher than 200 °C, the selectivity of DMCD increases, but the conversion rate of DMT decreases significantly. This comparison shows that when the reaction temperature of the fixed bed device is set at 200 °C, the conversion rate of DMT and the selectivity of DMCD are optimal.

[0054] In Comparative Example 5, when the reaction pressure rises to 1.5, the conversion rate of DMT does not change much, but the selectivity of DMCD decreases significantly. In Comparative Example 6, when the reaction pressure drops to 0.5, the conversion rate of DMT drops significantly, only 39.8%, and compared with Examples 1 and 2, it shows that when the reaction pressure is 1 MPa, the effect is optimal.

[0055] Continuous experiments were carried out on the fixed-bed reactor in Example 1, and the results showed that the catalyst could operate stably for more than 200 h.

[0056] Therefore, in the process method of using a nickel-based catalyst for preparing DMCD from DMT in the present invention, after dissolving DMT with an organic solvent and feeding it into a fixed bed, the use of a fixed-bed device can achieve the continuity of production, with a high hydrogenation conversion rate of DMT, and the catalyst can be reused repeatedly. In addition, the reaction pressure is limited to a low pressure (≤1 MPa) in this method, which is safer and has high practical value and industrial application prospects.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify or equivalently replace the technical solutions of the present invention, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A process for preparing DMCD from DMT using a nickel-based catalyst, characterized in that, It includes the following steps: S1. Prepare a nickel-based catalyst: Using a carbonate solution, a carrier solution, and an active metal salt solution as raw materials, after mixing and reacting, add an alkali solution to adjust the pH to alkaline until the color of the suspension changes from dark green to coffee color, let it stand and then centrifuge and dry, and obtain the catalyst after calcination and reduction reaction; S2. Put the obtained catalyst into a tablet press mold, perform tablet pressing on a tablet press, then use a mortar to crush the tablet-shaped catalyst, screen it, and load the catalyst into the middle of the bed layer of a fixed-bed reaction device. Fill a small amount of quartz wool under the bed layer, introduce hydrogen for 30 min to displace the air in the fixed bed, and then heat up the fixed-bed device; S3. After the temperature of the reaction bed reaction device rises to the initial reaction temperature, start the feed pump, send the dissolved DMT into the fixed-bed device, and start the hydrogenation reaction to continuously produce DMCD.

2. A process for preparing DMCD from DMT using the nickel-based catalyst according to claim 1, characterized in that: In S1, the carbonate is sodium carbonate, the alkali solution is sodium hydroxide, or the carbonate is ammonium bicarbonate, the alkali solution is ammonia water, and the concentration of the alkali solution is 0.1 - 3 mol / L.

3. A process for preparing DMCD from DMT using the nickel-based catalyst according to claim 1, characterized in that: In S1, the carrier is one or more of β-zeolite, USY zeolite, Al-SBA-15, ZSM-5, silica, and alumina; the active metal salt is one or a mixture of two or more of Pd, Ni, Co, Mo, Mn, Cu, Fe, Cr, Zn, and Mg, and the mass ratio of the carrier to the carbonate is 1 - 6:

3.

4. A process for preparing DMCD from DMT using the nickel-based catalyst according to claim 1, characterized in that: In S1, the temperature during the pH adjustment process is 30 - 100 °C, the calcination temperature is 400 - 800 °C, and the calcination time is 2 - 10 h; the reduction temperature is 300 - 600 °C, and the reduction time is 2 - 6 h.

5. A process for preparing DMCD from DMT using the nickel-based catalyst according to claim 1, characterized in that: In S3, the reaction temperature of the fixed-bed device is 200 - 230 °C, and the reaction pressure is 0.6 - 1 MPa.

6. The process method of using a nickel-based catalyst for preparing DMCD from DMT according to claim 1, characterized in that: In S3, the reaction temperature of the fixed-bed device is 200 °C, and the reaction pressure is 1 MPa.

7. A process for preparing DMCD from DMT using the nickel-based catalyst according to claim 1, characterized in that: In S3, DMT is dissolved in an organic solvent, the liquid-phase feed flow rate in the fixed-bed device is 0.1 - 0.6 ml / min, and the hydrogen flow rate is 5 - 30 ml / min.

8. A process for preparing DMCD from DMT using the nickel-based catalyst according to claim 1, characterized in that: In S3, the liquid-phase feed flow rate in the fixed-bed device is 0.25 ml / min, and the hydrogen flow rate is 4 ml / min.

9. A process for preparing DMCD from DMT using the nickel-based catalyst according to claim 1, characterized in that: In S3, the dissolved DMT is preheated before being pumped in, and hydrogen is preheated using a vaporizer, and the temperature of the vaporizer is 50 - 100 °C.

10. A process for preparing DMCD from DMT using the nickel-based catalyst according to claim 1, characterized in that: In S3, before starting the hydrogenation reaction, pump in a reducing gas to perform a pre-reduction treatment on the catalyst, and the treatment time is 30 min, and the reducing gas is high-purity hydrogen.

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