A catalyst for the regeneration of a dehydrating agent for 2-cyanopyridine and a preparation method thereof

Abstract

The present invention provides a catalyst for the regeneration of a dehydrating agent for 2-cyanopyridine and a preparation method thereof, belonging to the technical field of catalysts; the catalyst comprises, by weight percentage: 0.5-10% of a metal oxide, 0.5-3% of MgO-SiO2, and the balance being a carrier; the metal oxide contains In and Sn; the weight percentage of MgO in MgO-SiO2 is 30%-75%; in the catalyst of the present invention, through two impregnations, the carbonyl group in the amide is activated by two metal ions, In and Sn, and the magnesium oxide acting through SiO2 effectively activates hydrogen atoms and stabilizes the enamine intermediate, so that the reaction can dehydrate efficiently to obtain the target product; when the catalyst of the present invention is used in the regeneration reaction of the dehydrating agent for 2-cyanopyridine, the conversion rate of 2-pyridinecarboxamide can reach 80-98%, and the selectivity of 2-cyanopyridine > 99%, which is significantly higher than that of the same type of dehydrating catalyst.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalysts, and particularly relates to a catalyst for regenerating a dehydrating agent for 2-cyanopyridine and a preparation method thereof. Background Art

[0002] With the increasing attention to environmental protection by people, environmentally friendly chemical raw materials in chemical production have received more and more attention. In recent years, the green chemical raw material dimethyl carbonate (DMC) has been increasingly concerned. DMC is a green chemical and a clean organic chemical intermediate, which can replace highly toxic phosgene, methyl chloroformate, dimethyl sulfate, etc. as methylation or carbonylation reagents, and is now widely used in the production of various chemical products such as polycarbonate, polyurethane, long-chain alkyl carbonate, triphosgene, methyl phenylcarbamate, etc. The production methods of DMC mainly include phosgene methanol method, transesterification method, methanol oxidative carbonylation method and direct reaction of carbon dioxide with methanol. Among them, the phosgene method uses toxic phosgene as a reactant, causing serious environmental pollution and the by-product hydrogen chloride will corrode the reaction equipment, and it has been gradually phased out; the raw material source of the transesterification method is restricted by the petroleum industry, and the co-produced ethylene glycol or propylene glycol also has a certain restrictive effect on the production capacity; the catalyst used in the methanol oxidative carbonylation method is expensive, and some catalysts have a certain corrosiveness to the equipment; the urea alcoholysis method has good application prospects, and there have been reports of the start-up of a thousand-ton pilot plant, however, the generated ammonia will inhibit the rightward shift of the reaction equilibrium, resulting in a low yield. These methods are not ideal methods. The direct synthesis of DMC from CO2 and methanol has the advantages of reaction atom economy and few by-products, and is a sustainable green economic route, which has become a research hotspot in recent years.

[0003] In 2013, Japanese scientists reported the use of 2-cyanopyridine as an efficient dehydrating agent to achieve the near-stoichiometric conversion reaction of methanol to prepare dimethyl carbonate (DMC). At the same time, the preliminary research results showed that the dehydrating agent can be catalytically recycled (ChemSusChem 2013, 6, 1341), but the efficiency of this recycling process is very low. At present, when preparing DMC from methanol, CO2 and 2-cyanopyridine, a large amount of 2-pyridinecarboxamide will be produced as a by-product, which consumes the dehydrating agent 2-cyanopyridine, has no market-scale application route itself, and brings many difficulties to the separation and purification of the target product, and the energy consumption and cost are also greatly increased. Chen Xinzhi et al. developed a molecular sieve lead catalyst for catalyzing the dehydration reaction of amide compounds (CN112028726 A). The applicant of the present invention developed an alkaline metal-supported efficient catalyst for the dehydration reaction of primary amides (CN112495362 B). Summary of the Invention

[0004] The present invention overcomes the deficiencies of the prior art and provides a catalyst for the regeneration of dehydrating agents for 2-cyanopyridine and a preparation method thereof, which is used for the dehydration reaction of 2-pyridinecarboxamide to improve the catalytic activity of the dehydration reaction of 2-pyridinecarboxamide to produce 2-cyanopyridine.

[0005] To achieve the above object, the present invention is realized through the following technical solutions.

[0006] A catalyst for the regeneration of dehydrating agents for 2-cyanopyridine, comprising, by weight percentage: 0.5 - 10% of metal oxides, 0.5 - 3% of MgO-SiO2, and the rest being a carrier; the metal oxides contain In and Sn; the weight percentage of MgO in the MgO-SiO2 is 30% - 75%.

[0007] Preferably, the carrier is amorphous silica gel.

[0008] Preferably, the mass ratio of MgO to SiO2 is 1:1.

[0009] A preparation method of a catalyst for the regeneration of dehydrating agents for 2-cyanopyridine, comprising the following steps:

[0010] 1) Add the carrier to a tin chloride solution with a cation concentration of 0.01 - 0.1 g·mL -1 , stir evenly; let it stand at room temperature for 8 - 24 h, and then dry it.

[0011] 2) Add the substance obtained by drying in the previous step to an indium nitrate solution with a concentration of 0.01 - 0.1 g·mL -1 , stir evenly; let it stand at room temperature for 8 - 24 h, and then dry it.

[0012] 3) Calcinate the substance obtained by drying in the previous step, and add MgO-SiO2 after calcination to prepare the catalyst, and the added amount of MgO-SiO2 is 0.5 - 3% of the substance after calcination.

[0013] Preferably, the carrier is pre-baked at 300 - 500 °C for 2 - 10 hours.

[0014] Preferably, the drying in steps 2) and 3) is carried out at 80 - 150 °C for 12 - 36 h.

[0015] Preferably, the calcination in step 3) is carried out at 400 - 600 °C for 3 - 8 h.

[0016] Preferably, the MgO-SiO2 is prepared by mixing MgO and SiO2 and calcining at 300 - 600 °C for 2 - 8 h.

[0017] Preferably, the catalyst is tableted and used after being made into solid granular particles with a mesh size of 40 to 60.

[0018] The beneficial effects of the present invention compared with the prior art are as follows:

[0019] 1. In the catalyst of the present invention, the carbonyl group in the amide is activated by two metal ions, In and Sn, and the hydrogen atoms are effectively activated and the enamine intermediate is stabilized by the magnesium oxide acting through SiO2, so that the reaction can dehydrate efficiently and the target product can be obtained by conversion.

[0020] 2. The catalytic components used in the present invention use non-noble metal materials, which have the advantages of low cost, simple and practical preparation method, and being convenient for large-scale production; and the calcination temperature used in the preparation process of the catalyst is low, the performance is high, which is of great significance for reducing the energy consumption cost.

[0021] 3. When the catalyst adopted by the present invention is used for the regeneration reaction of the dehydrating agent of 2-cyanopyridine, the conversion rate of 2-pyridinecarboxamide can reach 80-98%, and the selectivity of 2-cyanopyridine > 99%, which is significantly higher than that of the same type of dehydrating catalyst. Specific Embodiments

[0022] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clear and understandable, the present invention will be further described in detail in combination with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. The technical solutions of the present invention will be described in detail below in combination with embodiments, but the protection scope is not limited by this.

[0023] Example 1

[0024] A catalyst for the regeneration of the dehydrating agent of 2-cyanopyridine, and the preparation method is as follows:

[0025] Weigh 15 g of amorphous silica gel as the carrier and bake it at 350 °C for 6 h. Prepare a tin chloride solution with a cation concentration of 0.02 g·mL -1 . Take 30 mL of this metal solution and add it to the amorphous silica gel solid, and stir evenly. Let it stand at room temperature for 12 h, and bake it at 120 °C for 24 h. Prepare 20 ml of an indium nitrate solution with a concentration of 0.04 g·mL -1 . Dissolve the dried substance obtained in the previous step in the indium nitrate solution and stir evenly. Let it stand at room temperature for 12 h, and bake it at 120 °C for 24 h. Bake the dried substance obtained in the previous step at 500 °C for 3 h, and add 0.45 g of MgO-SiO2 (mass ratio: 1:1) baked at 400 °C for 2 h after baking to obtain the catalyst.

[0026] Evaluate the activity of the prepared catalyst:

[0027] The powdered catalyst was tableted into solid particles of 40 - 60 mesh; 10 g of the particulate catalyst was filled into the isothermal section of a fixed-bed reactor, and the remaining space was filled with quartz sand; a 2-pyridinecarboxamide raw material was prepared, with DMF as the solvent and the concentration of 2-pyridinecarboxamide being 15%; nitrogen was used to purge and displace the air in the reactor and pipeline; the reactor was controlled to heat up to 300 °C, and the feed pump was used for feeding with a space velocity of 0.5 h -1 ; After the reaction ran for a period of time, samples were taken for analysis. The conversion rate of 2-pyridinecarboxamide was 85%, and the selectivity for 2-cyanopyridine was 99.2%.

[0028] Example 2

[0029] A catalyst for the regeneration of the dehydrating agent for 2-cyanopyridine, and the preparation method is as follows:

[0030] Weigh 20 g of amorphous silica gel as the carrier and bake it at 400 °C for 8 h. Prepare a tin chloride solution with a cation concentration of 0.04 g·mL -1 , take 20 mL of this metal solution and add it to the amorphous silica gel solid, and stir evenly. Let it stand at room temperature for 16 h, and then bake it at 100 °C for 20 h. Prepare 15 mL of an indium nitrate solution with a concentration of 0.03 g·mL -1 , dissolve the dried substance obtained in the previous step in the indium nitrate solution, and stir evenly. Let it stand at room temperature for 15 h, and then bake it at 100 °C for 12 h. Bake the dried substance obtained in the previous step at 450 °C for 5 h, and after roasting, add 0.6 g of MgO-SiO2 (mass ratio: 1:1) roasted at 500 °C for 4 h to obtain the catalyst.

[0031] The activity of the prepared catalyst was evaluated:

[0032] The powdered catalyst was tableted into solid particles of 40 - 60 mesh; 15 g of the particulate catalyst was filled into the isothermal section of a fixed-bed reactor, and the remaining space was filled with quartz sand; a 2-pyridinecarboxamide raw material was prepared, with DMF as the solvent and the concentration of 2-pyridinecarboxamide being 20%; nitrogen was used to purge and displace the air in the reactor and pipeline; the reactor was controlled to heat up to 280 °C, and the feed pump was used for feeding with a space velocity of 0.8 h -1 ; After the reaction ran for a period of time, samples were taken for analysis. The conversion rate of 2-pyridinecarboxamide was 87%, and the selectivity for 2-cyanopyridine was 99.3%.

[0033] Example 3

[0034] A catalyst for the regeneration of the dehydrating agent for 2-cyanopyridine, and the preparation method is as follows:

[0035] Weigh 30 g of amorphous silica gel as the carrier and bake it at 500 °C for 4 h. Prepare a tin chloride solution with a cation concentration of 0.05 g·mL -1 Take 25 mL of this metal solution and add it to the amorphous silica gel solid, and stir evenly. Let it stand at room temperature for 20 h and then bake it at 130 °C for 24 h. Prepare 20 mL of an indium nitrate solution with a concentration of 0.05 g·mL -1 Dissolve the dried material obtained in the previous step in the indium nitrate solution and stir evenly. Let it stand at room temperature for 24 h and then bake it at 130 °C for 36 h. Bake the dried material obtained in the previous step at 550 °C for 6 h. After baking, add 0.3 g of MgO-SiO2 (mass ratio: 7:3) baked at 450 °C for 3.5 h to obtain the catalyst.

[0036] Evaluate the activity of the prepared catalyst:

[0037] Press the powdered catalyst into tablets to form solid particles with a mesh size of 40-60; fill 8 g of the particulate catalyst into the isothermal section of a fixed-bed reactor, and fill the remaining space with quartz sand; prepare a 2-pyridinecarboxamide raw material with DMF as the solvent and a 2-pyridinecarboxamide concentration of 25%; use nitrogen to purge and replace the air in the reactor and pipeline; control the reactor to heat up to 320 °C, feed with a feed pump, and the space velocity is 1.0 h -1 ; After the reaction runs for a period of time, take samples for analysis. The conversion rate of 2-pyridinecarboxamide is 89%, and the selectivity of 2-cyanopyridine is 99.1%.

[0038] Example 4

[0039] A catalyst for the regeneration of a dehydrating agent for 2-cyanopyridine, and the preparation method is as follows:

[0040] Weigh 25 g of amorphous silica gel as the carrier and bake it at 450 °C for 5 h. Prepare a tin chloride solution with a cation concentration of 0.08 g·mL -1 Take 20 mL of this metal solution and add it to the amorphous silica gel solid, and stir evenly. Let it stand at room temperature for 8 h and then bake it at 150 °C for 12 h. Prepare 16 mL of an indium nitrate solution with a concentration of 0.06 g·mL -1 Dissolve the dried material obtained in the previous step in the indium nitrate solution and stir evenly. Let it stand at room temperature for 16 h and then bake it at 150 °C for 15 h. Bake the dried material obtained in the previous step at 400 °C for 7 h. After baking, add 0.35 g of MgO-SiO2 (mass ratio: 6:4) baked at 500 °C for 6 h to obtain the catalyst.

[0041] Evaluate the activity of the prepared catalyst:

[0042] The powdered catalyst is tableted into solid particles of 40 - 60 mesh; 20 g of the particulate catalyst is filled into the isothermal section of a fixed-bed reactor, and the remaining space is filled with quartz sand; a 2-pyridinecarboxamide raw material is prepared, with DMF as the solvent and the 2-pyridinecarboxamide concentration being 30%; nitrogen is used to purge and displace the air in the reactor and pipeline; the reactor is controlled to be heated to 360 °C, and the feed pump feeds the material with a space velocity of 1.2 h -1 ; After the reaction runs for a period of time, samples are taken for analysis, and the conversion rate of 2-pyridinecarboxamide is 91%, and the selectivity for 2-cyanopyridine is 99.2%.

[0043] Example 5

[0044] A catalyst for the regeneration of a dehydrating agent for 2-cyanopyridine, the preparation method being:

[0045] Weigh 20 g of amorphous silica gel as the carrier and bake it at 420 °C for 2.5 h. Prepare a stannous chloride solution with a cation concentration of 0.05 g·mL -1 ; Take 30 mL of this metal solution and add it to the amorphous silica gel solid, and stir evenly. Let it stand at room temperature for 15 h, and then bake it at 90 °C for 28 h. Prepare 25 mL of an indium nitrate solution with a concentration of 0.04 g·mL -1 ; Dissolve the dried material obtained in the previous step in the indium nitrate solution and stir evenly. Let it stand at room temperature for 10 h, and then bake it at 130 °C for 14 h. Bake the dried material obtained in the previous step at 480 °C for 6 h, and after baking, add 0.4 g of MgO-SiO2 (mass ratio: 3:7) baked at 420 °C for 4.5 h to obtain the catalyst.

[0046] Evaluate the activity of the prepared catalyst:

[0047] The powdered catalyst is tableted into solid particles of 40 - 60 mesh; 18 g of the particulate catalyst is filled into the isothermal section of a fixed-bed reactor, and the remaining space is filled with quartz sand; a 2-pyridinecarboxamide raw material is prepared, with DMF as the solvent and the 2-pyridinecarboxamide concentration being 18%; nitrogen is used to purge and displace the air in the reactor and pipeline; the reactor is controlled to be heated to 280 °C, and the feed pump feeds the material with a space velocity of 0.6 h -1 ; After the reaction runs for a period of time, samples are taken for analysis, and the conversion rate of 2-pyridinecarboxamide is 92%, and the selectivity for 2-cyanopyridine is 99.1%.

[0048] Example 6

[0049] A catalyst for the regeneration of a dehydrating agent for 2-cyanopyridine, the preparation method being:

[0050] Weigh 18 g of amorphous silica gel as the carrier and bake it at 380 °C for 5.5 h. Prepare a solution with a cation concentration of 0.07 g·mL-1 Of the tin chloride solution, take 26 mL of this metal solution and add amorphous silica solid, stir evenly. Let it stand for 10 h at room temperature and bake for 16 h at 85 °C. Prepare 0.04 g·mL -1 Of the indium nitrate solution 25 mL, dissolve the dried substance obtained in the previous step in the indium nitrate solution, stir evenly. Let it stand for 15 h at room temperature and bake for 16 h at 100 °C. Bake the dried substance obtained in the previous step at 420 °C for 4 h, and add 0.5 g of MgO - SiO2 (mass ratio: 1:1) baked at 350 °C for 2.5 h after baking to obtain the catalyst.

[0051] Evaluate the activity of the prepared catalyst:

[0052] Press the powdered catalyst into tablets to make solid granular particles of 40 - 60 mesh; fill 15 g of granular catalyst into the isothermal section of the fixed - bed reactor, and fill the remaining space with quartz sand; prepare the 2 - picolinamide raw material, the solvent is DMF, and the concentration of 2 - picolinamide is 35%; use nitrogen to purge and replace the air in the reactor and pipeline; control the reactor to heat up to 320 °C, feed with a feed pump, and the space velocity is 1.3 h -1 ; After the reaction runs for a period of time, sample and analyze. The conversion rate of 2 - picolinamide is 87%, and the selectivity of 2 - cyanopyridine is 99.2%.

[0053] Comparative Example 1

[0054] A catalyst for the regeneration of the dehydrating agent for 2 - cyanopyridine, the preparation method is as follows:

[0055] Weigh 15 g of amorphous silica as the carrier and bake it at 350 °C for 6 h. Add 0.45 g of MgO - SiO2 (mass ratio: 1:1) baked at 400 °C for 2 h to it to obtain the catalyst (without impregnation treatment with two metal components).

[0056] Evaluate the activity of the prepared catalyst:

[0057] Press the powdered catalyst into tablets to make solid granular particles of 40 - 60 mesh; fill 10 g of granular catalyst into the isothermal section of the fixed - bed reactor, and fill the remaining space with quartz sand; prepare the 2 - picolinamide raw material, the solvent is DMF, and the concentration of 2 - picolinamide is 15%; use nitrogen to purge and replace the air in the reactor and pipeline; control the reactor to heat up to 300 °C, feed with a feed pump, and the space velocity is 0.5 h -1 ; After the reaction runs for a period of time, sample and analyze. The conversion rate of 2 - picolinamide is 39%, and the selectivity of 2 - cyanopyridine is 42.8%.

[0058] Comparative Example 2

[0059] A catalyst for the regeneration of dehydrating agent for 2-cyanopyridine, and the preparation method is as follows:

[0060] Weigh 20 g of amorphous silica gel as the carrier and bake it at 400 °C for 8 h. Prepare a stannous chloride solution with a cation concentration of 0.04 g·mL -1 Take 20 mL of this metal solution and add it to the amorphous silica gel solid, and stir evenly. Let it stand at room temperature for 16 h and bake it at 100 °C for 20 h. Prepare 15 mL of indium nitrate solution with a concentration of 0.03 g·mL -1 Dissolve the dried substance obtained in the previous step in the indium nitrate solution and stir evenly. Let it stand at room temperature for 15 h and bake it at 100 °C for 12 h. Calcinate the dried substance obtained in the previous step at 450 °C for 5 h to obtain the catalyst (without adding MgO-SiO2).

[0061] Evaluate the activity of the prepared catalyst:

[0062] Press the powdered catalyst into tablets to form solid particles with a mesh size of 40-60; fill 15 g of granular catalyst into the constant temperature section of the fixed bed reactor, and fill the remaining space with quartz sand; prepare a 2-pyridinecarboxamide raw material with DMF as the solvent and a 2-pyridinecarboxamide concentration of 20%; use nitrogen to purge and replace the air in the reactor and pipeline; control the reactor to heat up to 280 °C, feed with a feed pump, and the space velocity is 0.8 h -1 ; After the reaction runs for a period of time, take samples for analysis. The conversion rate of 2-pyridinecarboxamide is 47%, and the selectivity of 2-cyanopyridine is 53.1%.

[0063] The above content is a further detailed description of the present invention in combination with specific preferred embodiments. It cannot be determined that the specific embodiments of the present invention are limited to this. For those of ordinary skill in the technical field to which the present invention belongs, without departing from the premise of the present invention, several simple deductions or substitutions can be made, and all should be regarded as belonging to the patent protection scope determined by the claims submitted by the present invention.

Claims

1. A catalyst for the regeneration of a dehydrating agent for 2-cyanopyridine, characterized in that, Comprising, by weight percentage: 0.5 - 10% metal oxide, 0.5 - 3% MgO - SiO₂, the balance being the carrier; the metal oxide is an oxide of In and Sn; the weight percentage of MgO in the MgO - SiO₂ is 30% - 75%; The carrier is amorphous silica gel; The preparation method of the catalyst comprises the following steps: 1) Add the carrier to a stannous chloride solution with a cation concentration of 0.01 - 0.1 g·mL -1 , stir evenly; let it stand at room temperature for 8 - 24 h, and then dry it; 2) Add the substance obtained from the previous drying step into an indium nitrate solution with a concentration of 0.01 - 0.1 g·mL -1 , stir evenly; let it stand at room temperature for 8 - 24 h, and then conduct drying; 3) Calcining the substance obtained by drying in the previous step, and adding MgO - SiO₂ after calcination to prepare the catalyst, the added amount of MgO - SiO₂ being 0.5 - 3% of the substance after calcination; the MgO - SiO₂ is prepared by mixing MgO and SiO₂ and calcining at 300 - 600 °C for 2 - 8 h.

2. A catalyst for the regeneration of a dehydrating agent for 2-cyanopyridine according to claim 1, characterized in that, The mass ratio of MgO to SiO₂ is 1:

1.

3. A catalyst for the regeneration of a dehydrating agent for 2-cyanopyridine according to claim 1, characterized in that, The carrier is pre - baked at 300 - 500 °C for 2 - 10 hours.

4. A catalyst for the regeneration of a dehydrating agent for 2-cyanopyridine according to claim 1, characterized in that, The drying in step 2) and step 3) is carried out at 80 - 150 °C for 12 - 36 h.

5. A catalyst for the regeneration of a dehydrating agent for 2-cyanopyridine according to claim 1, characterized in that, The calcination in step 3) is carried out at 400 - 600 °C for 3 - 8 h.

6. The catalyst for regenerating the dehydrating agent for 2-cyanopyridine according to claim 1, wherein The catalyst is tableted and used after being made into solid granular particles of 40 - 60 mesh.