Preparation method and application of Ni-based catalyst for synthesizing CHDA

Abstract

The invention discloses a preparation method of a Ni-based catalyst for synthesizing CHDA, which comprises the following steps: grinding biomass carbon, a nitrogen source and nickel salt as raw materials, and performing high-temperature carbonization in a tubular furnace in a nitrogen atmosphere to obtain a powdery nitrogen-doped catalyst; sodium carboxymethyl cellulose and a powdery nitrogen-doped catalyst are subjected to kneading, tabletting and heat treatment in a tubular furnace in a nitrogen atmosphere to obtain a columnar catalyst, the columnar catalyst is crushed and then filled in a reaction tube, and a product is obtained through gas reduction. The invention also discloses application of the Ni-based catalyst for synthesizing CHDA, water is taken as a solvent, terephthalic acid is taken as a raw material, a product CHDA is synthesized through hydrogenation in a fixed bed reactor, and the Ni-based catalyst is embedded in the fixed bed reactor. According to the invention, aggregation and leaching of Ni can be effectively limited, the hydrothermal stability of the catalyst is improved, the anchoring capability of the carrier to Ni nanoparticles is enhanced, the dispersity of the active component Ni is improved, and the activity of the catalyst is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical industry, and particularly relates to a preparation method and application of a Ni-based catalyst for synthesizing 1,4-cyclohexanedicarboxylic acid. Background Art

[0002] 1,4-cyclohexanedicarboxylic acid (CHDA) is a structurally symmetrical aliphatic dibasic acid and an important chemical intermediate. Since it does not contain benzene rings, it is less harmful to the human body and the environment. It has been successfully used in the preparation of thermoplastic polyester elastomers and new epoxy resins and other products. In addition, 1,4-cyclohexanedimethanol (CHDM) prepared from CHDA is also an important new polyester raw material. CHDA is mainly prepared by hydrogenation of terephthalic acid. Common preparation methods include esterification (or salt formation) hydrogenation of raw material PTA and direct hydrogenation.

[0003] US5118841A provides a process for preparing 1,4-cyclohexanedicarboxylic acid by hydrogenation of terephthalic acid salt: the reaction temperature is 200°C, the hydrogen pressure is 10-14MPa, under the action of 1% Ru / C catalyst, disodium terephthalate reacts with hydrogen to obtain disodium cyclohexanedicarboxylate, and CHDA is obtained after sulfuric acid acidification and recrystallization steps. The CHDA yield is about 90%. Hydrogenation using terephthalate as raw material has the advantages of high selectivity and high yield, and has little effect on reactor corrosion and catalyst performance, but acidification must be performed in post-treatment, the production process consumes a lot of energy and has high costs, and a large amount of industrial wastewater is generated.

[0004] JP2002069016A provides a process for preparing 1,4-cyclohexanedicarboxylic acid by hydrogenation of terephthalic acid-water system: using 5% Pd / C as catalyst, reaction temperature is 150°C, reaction pressure is 3MPa, PTA conversion rate is 99%, CHDA selectivity is 95%. This process has low reaction temperature and high yield, but using 5% Pd / C catalyst, the cost of precious metal catalyst is high.

[0005] CN105056997A and CN1915958 provide a catalyst prepared with relatively cheap precious metal ruthenium, which is applied to the process of preparing 1,4-cyclohexanedicarboxylic acid by hydrogenation of terephthalic acid-water (methanol) system. Under the conditions of reaction temperature of 110-150°C and hydrogen pressure of 3-5MPa, the yield of 1,4-cyclohexanedicarboxylic acid reaches about 95%. However, the use of precious metal ruthenium is large, which greatly increases the production cost of 1,4-cyclohexanedicarboxylic acid. At the same time, some non-precious metal catalysts have also been developed for aromatic acid hydrogenation. CN111068724B provides a catalyst with Cu-Fe-Re-PB / C as catalyst. Under the conditions of reaction temperature of 250°C and hydrogen pressure of 6.5MPa, the yield of 1,4-cyclohexanedicarboxylic acid can reach 89.2%. CN105032429A provides a Ni / C catalyst prepared by microwave heating for benzoic acid hydrogenation, and the yield of cyclohexanecarboxylic acid can reach 94.8% under the condition of reaction temperature of 200°C and hydrogen pressure of 5MPa. These catalysts have relatively low activity and high reaction temperature, so in the process of catalytic terephthalic acid aqueous phase hydrogenation, a method is needed to make the catalytic activity higher and the catalyst use cost lower. Summary of the invention

[0006] The object of the present invention is to provide a method for preparing a Ni-based catalyst for synthesizing CHDA and its application, so as to solve the above-mentioned problems existing in the catalyst for hydrogenation of terephthalic acid proposed in the background technology.

[0007] To achieve the above object, the present invention provides a method for preparing a Ni-based catalyst for synthesizing CHDA, comprising the following steps:

[0008] Firstly, biomass carbon, nitrogen source and nickel salt are used as raw materials, which are fully ground and then carbonized at high temperature in a tubular furnace under a nitrogen atmosphere to obtain a powdered nitrogen-doped catalyst;

[0009] Then, sodium carboxymethyl cellulose is used as a binder, and the binder and powdered nitrogen-doped catalyst are kneaded and tableted, and then heat-treated in a tubular furnace under a nitrogen atmosphere to obtain a columnar catalyst, which is crushed and loaded into a reaction tube, and then gas reduced to obtain the target catalyst; the reaction tube is a reaction tube in a fixed bed reactor for synthesizing CHDA.

[0010] In a specific embodiment, the mass fraction of Ni in the Ni-based catalyst is 0.5-50.0 wt%.

[0011] In a specific embodiment, the biomass carbon is one of cotton fiber, cellulose, sucrose, and glucose, the nitrogen source is one of urea, ethylenediamine, dicyandiamide, and melamine, and the nickel salt is one of nickel nitrate, nickel acetate, and nickel chloride.

[0012] In a specific embodiment, the raw material grinding time is 0.5 to 2 hours, the temperature of the raw material high temperature carbonization in the tube furnace after grinding is 500 to 800°C, and the nitrogen space velocity of the high temperature carbonization is 200 to 400 h -1 The heating rate of high temperature carbonization is 3-5°C / min, and the treatment time of high temperature carbonization is 1-4h.

[0013] In a specific embodiment, the ratio of the binder to the powdered nitrogen-doped catalyst is 1 / 4 to 20, the kneading time is 30 to 60 minutes, the tableting pressure is 10 to 25 MPa; the nitrogen space velocity of the heat treatment process is 200 to 400 h -1 , the temperature is 250-350℃, the heating rate is 3-5℃ / min, and the processing time is 1-4h.

[0014] In a specific embodiment, the columnar catalyst is crushed into 20-40 meshes and then loaded into the reaction tube.

[0015] In a specific embodiment, the reduction to obtain the target catalyst is carried out in a mixed atmosphere of nitrogen and hydrogen, with a hydrogen hourly velocity of 300 to 600 h -1 , V 氢气 / V 氮气 =1 / 2~10, the reduction temperature is 400~700℃, the heating rate is 3~5℃ / min, and the reduction time is 1~4h.

[0016] The present invention also provides an application of a Ni-based catalyst for synthesizing CHDA, which uses water as a solvent and terephthalic acid (PTA) as a raw material, is dissolved by a product 1,4-cyclohexanedicarboxylic acid (CHDA), is heated to 150-180° C. in a high-pressure reactor to dissolve and form a raw material liquid, and then is transported to a fixed-bed reactor by a high-temperature pump for a hydrogenation reaction, wherein the fixed-bed reactor is embedded with a Ni-based catalyst prepared by the preparation method of the Ni-based catalyst for synthesizing CHDA as described above.

[0017] In a specific embodiment, the amount of terephthalic acid added to the raw material liquid is 1 to 5 wt%, preferably 1 to 3 wt%; the amount of 1,4-cyclohexanedicarboxylic acid added is 5 to 40 wt%, preferably 15 to 35 wt%.

[0018] In a specific embodiment, the hydrogenation reaction pressure is 5.0-10.0 MPa, the reaction temperature is 180-220°C, and the feed mass space velocity of PTA is 0.3-0.9 h -1 , the molar ratio of hydrogen to PTA is 10 to 40 / 1.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The traditional process of preparing CHDA by hydrogenation of PTA is mainly a kettle process, which has problems such as easy crushing of the catalyst, complicated separation operation, and low production efficiency; the catalyst is mainly made of precious metals, which greatly increases the production cost of 1,4-cyclohexanedicarboxylic acid.

[0021] The present invention uses biomass carbon as a carbon source and obtains an embedded nitrogen-doped nickel-based catalyst by a one-step method. The embedded structure prepared by the one-step method can effectively limit the aggregation and leaching of Ni, greatly improving the hydrothermal stability of the catalyst. At the same time, through N-doping modification, the abundant nitrogen-containing groups in the carrier can provide sufficient binding sites to tightly capture Ni, thereby enhancing the anchoring ability of the carrier to Ni nanoparticles, which not only improves the dispersion of the active component Ni and the catalyst activity, but also further limits the aggregation and leaching of Ni, thereby improving the disadvantage of the traditional nickel catalyst that it is easy to agglomerate and deactivate.

[0022] The method of the present invention can make the yield of synthesizing 1,4-cyclohexanedicarboxylic acid greater than 93.0%, and the catalyst has a long service life. -1 Under the condition of , the catalyst can run for more than 720h in a single pass without obvious deactivation.

[0023] In addition to the above-described objects, features and advantages, the present invention has other objects, features and advantages. The present invention is further described in detail below. DETAILED DESCRIPTION

[0024] The embodiments of the present invention are described in detail below. The specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0025] A method for preparing a Ni-based catalyst for synthesizing CHDA of the present invention comprises the following steps:

[0026] Firstly, biomass carbon, nitrogen source and nickel salt are used as raw materials, which are fully ground and then carbonized at high temperature in a tubular furnace under a nitrogen atmosphere to obtain a powdered nitrogen-doped catalyst;

[0027] Then, sodium carboxymethyl cellulose is used as a binder, and the binder and powdered nitrogen-doped catalyst are kneaded and tableted, and then heat-treated in a tubular furnace under a nitrogen atmosphere to obtain a columnar catalyst, which is crushed and loaded into a reaction tube, and then gas reduced to obtain the target catalyst; the reaction tube is a reaction tube in a fixed bed reactor for synthesizing CHDA.

[0028] The mass fraction of Ni in the Ni-based catalyst is 0.5-50.0 wt%.

[0029] The biomass carbon is one of cotton fiber, cellulose, sucrose, and glucose; the nitrogen source is one of urea, ethylenediamine, dicyandiamide, and melamine; and the nickel salt is one of nickel nitrate, nickel acetate, and nickel chloride.

[0030] The raw material grinding time is 0.5 to 2 hours. After the raw material is ground, the temperature of high-temperature carbonization in a tube furnace is 500 to 800°C, and the nitrogen space velocity of high-temperature carbonization is 200 to 400 hours. -1 The nitrogen space velocity for high temperature carbonization is preferably 300 h -1 The heating rate of high temperature carbonization is 3-5°C / min, and the treatment time of high temperature carbonization is 1-4h.

[0031] The ratio of the binder to the powdered nitrogen-doped catalyst is 1 / 4 to 20, the kneading time is 30 to 60 minutes, the tableting pressure is 10 to 25 MPa; the nitrogen space velocity of the heat treatment process is 200 to 400 h -1 The optimal heat treatment process nitrogen space velocity is 300h -1 , the temperature is 250-350℃, the heating rate is 3-5℃ / min, and the processing time is 1-4h.

[0032] The columnar catalyst is crushed into 20-40 meshes and then loaded into a reaction tube. The reaction tube is a reaction tube in a fixed bed reactor.

[0033] The reduction to obtain the target catalyst is carried out in a mixed atmosphere of nitrogen and hydrogen, with a hydrogen hourly velocity of 300 to 600 h -1 The preferred hydrogen space velocity is 600 h -1 , V 氢气 / V 氮气 =1 / 2~10, V represents gas flow rate, reduction temperature is 400~700℃, heating rate is 3~5℃ / min, reduction time is 1~4h.

[0034] The present invention also provides an application of a Ni-based catalyst for synthesizing CHDA, which uses water as a solvent and terephthalic acid as a raw material, is dissolved by a product 1,4-cyclohexanedicarboxylic acid, is heated to 150-180° C. in a high-pressure reactor to dissolve to form a raw material liquid, and is then transported to a fixed-bed reactor by a high-temperature pump for a hydrogenation reaction, wherein the fixed-bed reactor is embedded with a Ni-based catalyst prepared by the preparation method of the Ni-based catalyst for synthesizing CHDA as described above.

[0035] The amount of terephthalic acid added to the raw material liquid is 1-5wt%, preferably 1-3wt%; the amount of 1,4-cyclohexanedicarboxylic acid added is 5-40wt%, preferably 15-35wt%.

[0036] The hydrogenation reaction pressure is 5.0-10.0 MPa, the reaction temperature is 180-220°C, and the feed mass space velocity of PTA is 0.3-0.9 h -1 , the molar ratio of hydrogen to PTA is 10 to 40 / 1.

[0037] Example A1

[0038] Preparation of catalyst:

[0039] Weigh 14.0g of cellulose, 6.0g of melamine and 10.0g of nickel acetate, grind them thoroughly in a mortar, then transfer them to a crucible, place them in a tube furnace, heat them to 600℃ at a rate of 3.3℃ / min at a N2 flow rate of 100mL / min, and calcine them for 2h to obtain a powder catalyst, add 1.46g of CMC and mix them with the powder catalyst, add purified water and knead and mix them, press them into shape with a tablet press (15MPa), heat them to 300℃ at a rate of 3.3℃ / min at a nitrogen flow rate of 100mL / min and calcine them for 2h, and the content of Ni in the active component of the obtained catalyst is 24.0%, which is recorded as Ni / NC-1 catalyst.

[0040] Example A2

[0041] Except that cellulose was replaced by glucose, the remaining steps were the same as those in Example A1, and the Ni loading amount in the obtained catalyst was 25.2%, which was recorded as Ni / NC-2 catalyst.

[0042] Example A3

[0043] Except for replacing cellulose with sucrose, the remaining steps were the same as those in Example A1, and the Ni loading amount in the obtained catalyst was 24.6%, which was recorded as Ni / NC-3 catalyst.

[0044] Example A4

[0045] Except that melamine was replaced by dicyandiamide, the remaining steps were the same as those in Example A1, and the Ni loading amount in the obtained catalyst was 24.5%, which was recorded as Ni / NC-4 catalyst.

[0046] Example A5

[0047] Except that the mass of nickel acetate was changed to 6.66 g and the mass of CMC was changed to 1.34 g, the remaining steps were the same as Example A1, and the Ni loading amount in the obtained catalyst was 17.5%, which was recorded as Ni / NC-5 catalyst.

[0048] Example A6

[0049] Except that the mass of nickel acetate was changed to 13.34 g and the mass of CMC was changed to 1.59 g, the remaining steps were the same as Example A1, and the Ni loading amount in the obtained catalyst was 29.6%, which was recorded as Ni / NC-6 catalyst.

[0050] Example A7

[0051] Except that the mass of nickel acetate was changed to 20.0 g and the mass of CMC was changed to 1.83 g, the remaining steps were the same as Example A1, and the Ni loading amount in the obtained catalyst was 38.4%, which was recorded as Ni / NC-7 catalyst.

[0052] Example A8

[0053] Except that the mass of cellulose was changed to 18.0 g, the mass of melamine was changed to 2.0 g, the mass of nickel acetate was changed to 13.34 g, and the mass of CMC was changed to 1.62 g, the remaining steps were the same as those in Example A1, and the Ni loading in the obtained catalyst was 29.0%, which was recorded as Ni / NC-8 catalyst.

[0054] Embodiment A9

[0055] Except that the mass of cellulose was changed to 10.0 g, the mass of melamine was changed to 10.0 g, the mass of nickel acetate was changed to 13.34 g, and the mass of CMC was changed to 1.55 g, the remaining steps were the same as those in Example A1, and the Ni loading in the obtained catalyst was 30.2%, which was recorded as Ni / NC-9 catalyst.

[0056] Embodiment A10

[0057] Except that the mass of CMC was changed to 0.75 g, the remaining steps were the same as those in Example A6, and the Ni loading amount in the obtained catalyst was 30.3%, which was recorded as Ni / NC-10 catalyst.

[0058] Embodiment A11

[0059] Except that the mass of CMC was changed to 2.52 g, the remaining steps were the same as those in Example A6, and the Ni loading amount in the obtained catalyst was 28.8%, which was recorded as Ni / NC-11 catalyst.

[0060] Comparative Example A1

[0061] Except that the mass of cellulose, melamine, nickel acetate and CMC were changed to 20.0 g, 0.0 g, 13.34 g and 1.64 g, the remaining steps were the same as those in Example A1, and the Ni loading amount in the obtained catalyst was 28.7%, which was recorded as Ni / NC-12 catalyst.

[0062] Comparative Example A2

[0063] A commercial carbon-supported nickel catalyst was used, wherein the Ni loading in the catalyst was 30.0%.

[0064] Catalyst Evaluation:

[0065] The columnar catalyst obtained above was crushed into 20-40 meshes and loaded into a reaction tube with an inner diameter of 13 mm. In an atmosphere with a hydrogen flow rate of 40 ml / min and a nitrogen flow rate of 160 ml / min, the temperature was raised to 500°C and reduced for 4 hours. After the temperature was lowered to 200°C, the catalyst was evaluated in a fixed bed reactor. The catalyst loading was 4 g (20-40 meshes). The reaction evaluation pressure was 8.0 MPa, the reaction temperature was 200°C, and the mass space velocity was 0.6 h -1 , the molar ratio of hydrogen to PTA is 20.0. The evaluation results are shown in Table 1.

[0066] Table 1. Catalyst evaluation:

[0067]

[0068]

[0069] It can be seen from Examples A1 to A4 in Table 1 that the embedded nitrogen-doped nickel-based catalyst prepared by the one-step method is applied to the process of catalyzing terephthalic acid to synthesize 1,4-cyclohexanedicarboxylic acid, and the yield of the obtained 1,4-cyclohexanedicarboxylic acid is greater than 87.8%.

[0070] Comparative Examples A1, A5-A7, the effect of the catalyst Ni loading on the catalytic reaction was optimized, and the preferred nickel loading was 17.5-38.5%.

[0071] By comparing Examples A6, A8, A9 and Comparative Example A1, it can be seen that the catalyst modified by N doping can effectively improve the activity of the catalyst and the product yield. Preferably, the ratio of the carbon source to the nitrogen source is 1 to 9:1.

[0072] Comparative Examples A6, A10, and A11 show that as the amount of binder CMC added increases, the reaction yield decreases significantly. The main reason may be that the addition of the binder covers part of the active components of the catalyst, reducing the activity of the catalyst. Preferably, the ratio of the amount of CMC added to the powder catalyst is 1 / 5.7 to 19.

[0073] Catalyst life evaluation:

[0074] The catalyst of Example A6 and the catalysts of Comparative Examples A1 and A2 were evaluated for long-term life respectively. The reaction conditions were as follows: the evaluation was conducted on a fixed bed reactor with an inner diameter of 13 mm, and the catalyst loading was 4 g (20-40 mesh). The reaction evaluation conditions were: pressure 8.0 MPa, reaction temperature 200°C, molar ratio of hydrogen to PTA 20.0, and raw material PTA feed mass space velocity 0.6 h -1 The evaluation results are shown in Table 2.

[0075] Table 2. Catalyst life evaluation:

[0076]

[0077]

[0078] Comparing the data in Table 2, it can be seen that when the raw material PTA feed mass space velocity is 0.6h -1 When the catalyst activity and selectivity did not decrease significantly during the 720h life evaluation period, the catalyst deactivation was obvious for the undoped N catalyst and the commercial catalyst. This indicates that the in-situ prepared embedded nitrogen-doped nickel-based catalyst not only improves the activity of the catalyst, but also further limits the aggregation and leaching of Ni, thus improving the disadvantage of the catalyst being easily agglomerated and deactivated.

[0079] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions and substitutions can be made without departing from the concept of the present invention, which should be regarded as belonging to the protection scope of the present invention.

Claims

1. A method for preparing a Ni-based catalyst for synthesizing CHDA, characterized in that: The following steps are involved: Firstly, biomass carbon, nitrogen source and nickel salt are used as raw materials, which are fully ground and then carbonized at high temperature in a tubular furnace under a nitrogen atmosphere to obtain a powdered nitrogen-doped catalyst; Then, sodium carboxymethyl cellulose is used as a binder, and the binder and powdered nitrogen-doped catalyst are kneaded and tableted, and then heat-treated in a tubular furnace under a nitrogen atmosphere to obtain a columnar catalyst, which is crushed and loaded into a reaction tube, and then gas reduced to obtain the target catalyst; the reaction tube is a reaction tube in a fixed bed reactor for synthesizing CHDA.

2. The method for preparing a Ni-based catalyst for synthesizing CHDA according to claim 1, wherein The mass fraction of Ni in the Ni-based catalyst is 0.5-50.0 wt%.

3. The method for preparing a Ni-based catalyst for synthesizing CHDA according to claim 1, characterized in that: The biomass carbon is one of cotton fiber, cellulose, sucrose, and glucose; the nitrogen source is one of urea, ethylenediamine, dicyandiamide, and melamine; and the nickel salt is one of nickel nitrate, nickel acetate, and nickel chloride.

4. The method for preparing a Ni-based catalyst for synthesizing CHDA according to claim 1, wherein The raw material grinding time is 0.5 to 2 hours. After the raw material is ground, the temperature of high-temperature carbonization in a tube furnace is 500 to 800°C, and the nitrogen space velocity of high-temperature carbonization is 200 to 400 hours. -1 The heating rate of high temperature carbonization is 3-5°C / min, and the treatment time of high temperature carbonization is 1-4h.

5. The method for preparing a Ni-based catalyst for synthesizing CHDA according to claim 1, wherein The ratio of the binder to the powdered nitrogen-doped catalyst is 1 / 4 to 20, the kneading time is 30 to 60 minutes, the tableting pressure is 10 to 25 MPa; the nitrogen space velocity of the heat treatment process is 200 to 400 h -1 , the temperature is 250-350℃, the heating rate is 3-5℃ / min, and the processing time is 1-4h.

6. The method for preparing a Ni-based catalyst for synthesizing CHDA according to claim 1, characterized in that: The columnar catalyst is crushed into 20-40 meshes and then loaded into the reaction tube.

7. The method for preparing a Ni-based catalyst for synthesizing CHDA according to claim 1, characterized in that: The reduction to obtain the target catalyst is carried out in a mixed atmosphere of nitrogen and hydrogen, with a hydrogen hourly velocity of 300 to 600 h -1 , V 氢气 / V 氮气 =1 / 2~10, the reduction temperature is 400~700℃, the heating rate is 3~5℃ / min, and the reduction time is 1~4h.

8. An application of a Ni-based catalyst for synthesizing CHDA, characterized in that: Water is used as solvent and terephthalic acid is used as raw material. The product 1,4-cyclohexanedicarboxylic acid is used as dissolution aid, and the raw material liquid is heated to 150-180° C. in a high-pressure reactor to dissolve and form a raw material liquid, which is then transported to a fixed bed reactor by a high-temperature pump for hydrogenation reaction. The fixed bed reactor is embedded with a Ni-based catalyst prepared by the preparation method of a Ni-based catalyst for synthesizing CHDA as described in any one of claims 1 to 7.

9. The use of a Ni-based catalyst for synthesizing CHDA according to claim 8, characterized in that: The amount of terephthalic acid added to the raw material liquid is 1-5wt%, preferably 1-3wt%; the amount of 1,4-cyclohexanedicarboxylic acid added is 5-40wt%, preferably 15-35wt%.

10. The use of a Ni-based catalyst for synthesizing CHDA according to claim 8, characterized in that: The hydrogenation reaction pressure is 5.0-10.0 MPa, the reaction temperature is 180-220°C, and the feed mass space velocity of PTA is 0.3-0.9 h -1 , the molar ratio of hydrogen to PTA is 10 to 40 / 1.

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