Preparation method and application of nitrogen-doped non-noble metal catalyst

Abstract

The invention provides a preparation method of a nitrogen-doped non-noble metal catalyst. The preparation method comprises the following steps: mixing ethylenediaminetetraacetic acid, triethylamine, a nickel source and a cobalt source in a DMF (Dimethyl Formamide) solution, and aging; and centrifuging, drying and calcining at high temperature to obtain the nitrogen-doped non-noble metal catalyst with the average particle size of 10-50nm. According to the preparation method of the nitrogen-doped non-noble metal catalyst provided by the invention, the prepared nitrogen-doped non-noble metal catalyst has the following beneficial effects that the complex metal ions are adopted as the precursor, the nitrogen-doped non-noble metal nanoparticles are prepared by a high-temperature calcination method, and the catalyst obtained by the method has the characteristics of high dispersity, high catalytic activity and high catalytic activity. The preparation method is simple and good in repeatability; and the synthesis steps are simple, and the cost is low. The nitrogen element is introduced, so that the deamination reaction can be effectively inhibited, and the yield of m-phenylenediamine is improved. When the prepared catalyst is applied to an isophthalonitrile hydrogenation process, extremely high yield of m-phenylenediamine can be maintained under mild reaction conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of catalyst preparation, and in particular to a preparation method of a nitrogen-doped non-precious metal catalyst and application thereof. Background Art

[0002] Meta-phenylenediamine, molecular formula is C8H 12 N2, with the simple formula of MXDA, is a colorless, transparent liquid with almond flavor at room temperature. It is soluble in water and organic solvents such as methanol, ethanol and toluene. It is an important chemical raw material.

[0003] At present, the conventional preparation method of MXDA in industry mainly adopts the catalytic hydrogenation process of isophthalonitrile (IPN), mainly using Raney Ni as the catalyst, with a yield of about 85%. However, Raney Ni is extremely flammable when exposed to air and has certain dangers. The use of supported catalysts instead of Raney Ni catalysts can not only improve the reaction selectivity, but also has the characteristics of safety and environmental protection.

[0004] The existing supported catalysts used for preparing MXDA by hydrogenation of IPN mainly include: supported cobalt-based catalysts with added second metals Cu, Cr, Mn, Mo, and Mg; nickel / SiO2 catalysts; nickel-based catalysts with skeleton nickel as the main catalyst and auxiliary components selected from metals such as Fe, Cr, Pb, and Mn. However, these catalysts have the problems of high reaction pressure and short catalyst cycle life when used for preparing MXDA by hydrogenation of IPN. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a preparation method of a nitrogen-doped non-precious metal catalyst and its application, and the specific technical solution is as follows:

[0006] A method for preparing a nitrogen-doped non-precious metal catalyst comprises the following steps:

[0007] Step 1: ethylenediaminetetraacetic acid, triethylamine, nickel source and cobalt source are mixed in DMF solution and aged;

[0008] Step 2: After centrifugation, drying and high-temperature calcination, the nitrogen-doped non-precious metal catalyst with an average particle size of 10 to 50 nm is obtained.

[0009] Preferably, step 1 specifically includes the following sub-steps:

[0010] Step 1.1: vector preparation;

[0011] Step 1.2: Add ethylenediaminetetraacetic acid and triethylamine into DMF to prepare solution A;

[0012] Step 1.3: Dissolve the nickel source and the cobalt source in DMF to prepare solution B;

[0013] Step 1.4: The carrier, solution A and solution B are mixed evenly and aged.

[0014] Preferably:

[0015] The carrier is one or more of calcium oxide, magnesium oxide, aluminum oxide and zirconium oxide;

[0016] The nickel source is nickel nitrate hexahydrate;

[0017] The cobalt source is cobalt nitrate hexahydrate.

[0018] Preferably, the carrier is a CaO carrier, and the preparation of the CaO carrier specifically comprises the following steps: placing egg shells in a quartz boat with a cover, calcining them at high temperature in a tube furnace, and then taking them out after cooling to 80° C., thereby obtaining the CaO carrier.

[0019] Preferably, the molar ratio of nickel nitrate hexahydrate, cobalt nitrate hexahydrate and CaO in the mixture of step 1.4 is (0.05-0.2):(0.05-0.2):1.

[0020] Preferably, the molar ratio of ethylenediaminetetraacetic acid, triethylamine, nickel nitrate hexahydrate and cobalt nitrate hexahydrate in the mixture of step 1.4 is (8-16):(8-16):1:3.

[0021] Preferably, in the mixture of step 1.4, the concentration of EDTA is 0.4-1.0 mol / L, the concentration of triethylamine is 0.4-1.0 mol / L, the concentration of nickel nitrate hexahydrate is 0.025-0.05 mol / L, the concentration of cobalt nitrate hexahydrate is

[0022] 0.075~0.15mol / L.

[0023] Preferably:

[0024] The molar ratio of nickel to cobalt in the nitrogen-doped non-precious metal catalyst is 1:5, and the mass proportion of nickel and cobalt is 20% to 60%;

[0025] The aging time in step 1 is 18 to 72 hours;

[0026] In step 2, the centrifugal speed is 8000 rpm, the centrifugal time is 3 min, and after centrifugation, the mixture is repeatedly washed with MDF 2 to 6 times;

[0027] In step 2, the drying time is 12 to 34 hours and the drying temperature is 70 to 120° C.

[0028] In step 2, the high temperature calcination method is to increase the temperature to 500-900° C. at a heating rate of 2.5° C. / min in a nitrogen atmosphere and calcine for 1-6 hours.

[0029] The present invention also provides an application of a nitrogen-doped non-precious metal catalyst, wherein the nitrogen-doped non-precious metal catalyst prepared by any one of the preparation methods described above is used to catalyze the hydrogenation of isophthalonitrile to prepare meta-xylylenediamine, and the catalytic hydrogenation of isophthalonitrile to prepare meta-xylylenediamine specifically comprises the following steps:

[0030] Step 10: adding the nitrogen-doped non-precious metal catalyst, isophthalonitrile and solvent into a batch pressure reactor;

[0031] Step 20: After replacing the air in the reactor with N2 and H2 for 2 to 4 times, introduce H2 to stabilize the internal pressure at 0.5 MPa;

[0032] Step 30: heating, stirring when the temperature reaches the first temperature, and increasing the internal pressure to the first pressure;

[0033] Step 40: After the reaction is completed, the nitrogen-doped non-precious metal catalyst and the reaction liquid are separated, and the reaction liquid is the meta-xylylenediamine.

[0034] Preferably:

[0035] The mass ratio of the nitrogen-doped non-precious metal catalyst, isophthalonitrile and solvent is 1:(10-30):(70-100).

[0036] The solvent is a mixture of methanol and toluene, wherein the mass ratio of methanol to toluene is 1:4.

[0037] In step 30, the first temperature is 80-160° C., and the first pressure is 1-10 MPa;

[0038] The reaction time in step 40 is 1 to 10 hours.

[0039] The method for preparing the nitrogen-doped non-precious metal catalyst provided by the present invention has the following beneficial effects:

[0040] 1. Using complex metal ions as precursors, nitrogen-doped non-precious metal nanoparticles are prepared by high-temperature calcination. The catalyst obtained by this method has the advantages of high dispersibility, simple preparation method, good repeatability, etc.; the synthesis steps are simple and the cost is low.

[0041] 2. The introduction of nitrogen can effectively inhibit the deamination reaction, thereby increasing the yield of meta-phenylenediamine.

[0042] 3. The prepared catalyst can maintain a very high yield of meta-phenylenediamine under mild reaction conditions when used in the isophthalonitrile hydrogenation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art are briefly introduced below.

[0044] Figure 1 A transmission electron microscope (TEM) photograph of a nitrogen-doped non-precious metal catalyst provided in an embodiment of the present invention;

[0045] Figure 2 A high-resolution transmission electron microscopy (HRTEM) image of a nitrogen-doped non-precious metal catalyst provided in an embodiment of the present invention;

[0046] Figure 3 N1s fine spectrum of the nitrogen-doped non-precious metal catalyst provided in the embodiment of the present invention;

[0047] Figure 4 A graph showing how the conversion of isophthalonitrile and the selectivity of meta-xylylenediamine change with the number of cycles during a catalytic cycle experiment of isophthalonitrile hydrogenation using a nitrogen-doped non-noble metal catalyst provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0048] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is described in detail below in conjunction with the accompanying drawings. The description in this part is only exemplary and explanatory and should not have any limiting effect on the protection scope of the present invention.

[0049] This embodiment provides a method for preparing a nitrogen-doped non-precious metal catalyst, comprising the following steps:

[0050] Step 1: EDTA, triethylamine, nickel source and cobalt source are mixed in DMF solution and aged.

[0051] Step 2: After centrifugation, drying and high-temperature calcination, a nitrogen-doped non-precious metal catalyst with an average particle size of 10 to 50 nm is obtained.

[0052] The method for preparing the nitrogen-doped non-precious metal catalyst provided in this embodiment has the following beneficial effects:

[0053] 1. Using complex metal ions as precursors, nitrogen-doped non-precious metal nanoparticles are prepared by high-temperature calcination. The catalyst obtained by this method has the advantages of high dispersibility, simple preparation method, good repeatability, etc.; the synthesis steps are simple and the cost is low.

[0054] 2. The introduction of nitrogen can effectively inhibit the deamination reaction, thereby increasing the yield of meta-phenylenediamine.

[0055] 3. The prepared catalyst can maintain a very high yield of meta-phenylenediamine under mild reaction conditions when used in the isophthalonitrile hydrogenation process.

[0056] Furthermore, step 1 specifically includes the following sub-steps:

[0057] Step 1.1: Vector preparation.

[0058] Step 1.2: Add ethylenediaminetetraacetic acid and triethylamine into DMF to prepare solution A.

[0059] Step 1.3: Dissolve the nickel source and the cobalt source in DMF to prepare solution B.

[0060] Step 1.4: Mix the carrier, solution A and solution B evenly and age them.

[0061] Further:

[0062] The carrier is one or more of calcium oxide, magnesium oxide, aluminum oxide and zirconium oxide.

[0063] The nickel source was nickel nitrate hexahydrate.

[0064] The cobalt source was cobalt nitrate hexahydrate.

[0065] Furthermore, the carrier is a CaO carrier, and the preparation of the CaO carrier specifically includes the following steps: placing the egg shell in a quartz boat with a cover, calcining it at high temperature in a tube furnace, and then taking it out after cooling it to 80° C., thereby obtaining the CaO carrier.

[0066] Furthermore, in the mixture of step 1.4, the molar ratio of nickel nitrate hexahydrate, cobalt nitrate hexahydrate and CaO is (0.05-0.2):(0.05-0.2):1.

[0067] Furthermore, in the mixture of step 1.4, the molar ratio of ethylenediaminetetraacetic acid, triethylamine, nickel nitrate hexahydrate and cobalt nitrate hexahydrate is (8-16):(8-16):1:3.

[0068] Furthermore, in the mixture of step 1.4, the concentration of EDTA is 0.4-1.0 mol / L, the concentration of triethylamine is 0.4-1.0 mol / L, the concentration of nickel nitrate hexahydrate is 0.025-0.05 mol / L, and the concentration of cobalt nitrate hexahydrate is 0.075-0.15 mol / L.

[0069] Further:

[0070] The molar ratio of nickel to cobalt in the nitrogen-doped non-precious metal catalyst is 1:5, and the mass proportion of nickel and cobalt is 20% to 60%.

[0071] The aging time in step 1 is 18 to 72 hours.

[0072] In step 2, the centrifugal speed is 8000 rpm, the centrifugal time is 3 min, and after centrifugation, the sample is repeatedly washed with MDF 2 to 6 times.

[0073] In step 2, the drying time is 12 to 34 hours, and the drying temperature is 70 to 120°C.

[0074] In step 2, the high temperature calcination method is to increase the temperature to 500-900° C. at a heating rate of 2.5° C. / min in a nitrogen atmosphere and calcine for 1-6 hours.

[0075] Furthermore, in step 2, the high temperature calcination temperature is 600° C. and the calcination time is 2 h.

[0076] This embodiment also provides an application of a nitrogen-doped non-precious metal catalyst, wherein the nitrogen-doped non-precious metal catalyst prepared by any of the preparation methods described above is used to catalyze the hydrogenation of isophthalonitrile to prepare meta-xylylenediamine, and the catalytic hydrogenation of isophthalonitrile to prepare meta-xylylenediamine specifically includes the following steps:

[0077] Step 10: Add the nitrogen-doped non-precious metal catalyst, isophthalonitrile and solvent into a batch pressure reactor.

[0078] Step 20: After replacing the air in the reactor with N2 and H2 for 2 to 4 times, introduce H2 to stabilize the internal pressure at 0.5 MPa.

[0079] Step 30: heating, stirring when the temperature reaches the first temperature, and increasing the internal pressure to the first pressure.

[0080] Step 40: After the reaction is completed, the nitrogen-doped non-precious metal catalyst and the reaction liquid are separated, and the reaction liquid is meta-xylylenediamine.

[0081] Further:

[0082] The mass ratio of the nitrogen-doped non-precious metal catalyst, isophthalonitrile and solvent is 1:(10-30):(70-100).

[0083] The solvent is a mixture of methanol and toluene, wherein the mass ratio of methanol to toluene is 1:4.

[0084] In step 30, the first temperature is 80-160° C., and the first pressure is 1-10 MPa.

[0085] The reaction time in step 40 is 1 to 10 hours.

[0086] Two specific embodiments are provided below. The provided embodiments may enable those skilled in the art to more fully understand the present invention, but do not limit the present invention in any way.

[0087] Example 1

[0088] 1) 2.34 g of ethylenediaminetetraacetic acid and 0.81 g of triethylamine were added to 40 mL of DMF solution to prepare solution A, and 0.29 g of nickel nitrate hexahydrate and 0.87 g of cobalt nitrate hexahydrate were dissolved in 40 mL of DMF solution to prepare solution B;

[0089] 2) Weigh 4g egg shell (calcium oxide yield 50%) and place it in a covered quartz boat, heat it to 900℃ at a rate of 5℃ / min and keep it in air for 2h. Then cool it to 80℃ (to prevent calcium oxide from absorbing water and deteriorating due to low temperature), take it out, grind it into powder to obtain CaO;

[0090] 3) uniformly mixing solution B, solution A and CaO, stirring at 80°C for 1 h, and then aging at 80°C for 28 h;

[0091] 4) The reaction solution in step 3) was centrifuged at 8000 rpm for 3 min, the separated sample was washed three times with DMF, and the filtered solid sample was dried at 80° C. for 36 h to obtain N-Ni1Co5 / CaO precursor;

[0092] 5) 1.5 g of the nitrogen-doped catalyst in step 3) was taken and recorded as: N-Ni1Co5 / CaO precursor was placed in a tube furnace and calcined at 600° C. in a nitrogen atmosphere for 2 h to obtain a black N-Ni1Co5 / CaO catalyst;

[0093] The obtained N-Ni1Co5 / CaO catalyst was structurally characterized. Figure 1 TEM photo of the catalyst in the example. It can be seen that the nickel-cobalt alloy nanoparticles are uniformly dispersed on the surface of the carrier, and the average particle size is about 10 nm. Figure 2 This is a high-resolution transmission electron microscopy (HRTEM) image of the prepared catalyst, in which the lattice spacing is 0.206nm, corresponding to the (111) crystal plane of NiCo Alloy, and the crystal plane spacing is 0.341nm corresponding to the (002) crystal plane of C. Figure 3 This is the N1s fine spectrum of the prepared catalyst, in which the pyridinic N content is as high as 50.82%.

[0094] 6) Add 0.5 g of the N-Ni1Co5 / CaO catalyst prepared above, 5 g of isophthalonitrile, 7 mL of methanol, and 28 mL of toluene into a 100 mL lined autoclave, and react at 140° C. and 3.0 MPa for 3 h;

[0095] The conversion rate of isophthalonitrile was 99.0%, and the selectivity of meta-xylylenediamine was 97.5%.

[0096] 7) Figure 4 The conversion rate of isophthalonitrile and the selectivity of meta-xylylenediamine vary with the number of cycles during the catalytic cycle experiment of isophthalonitrile hydrogenation of the N-Ni1Co5 / CaO catalyst obtained in Example 1. It can be seen that after ten cycles, the catalytic activity remains stable, proving that the N-Ni1Co5 / CaO catalyst has high stability.

[0097] Example 2

[0098] 1) 4.68 g of ethylenediaminetetraacetic acid and 1.92 g of triethylamine were added to 40 mL of DMF solution to prepare solution A, and 0.58 g of nickel nitrate hexahydrate and 1.74 g of cobalt nitrate hexahydrate were dissolved in 40 mL of DMF solution to prepare solution B;

[0099] 2) Weigh 4g egg shell (calcium oxide yield 50%) and place it in a covered quartz boat, heat it to 900℃ at a rate of 5℃ / min and keep it in air for 2h. Then cool it to 80℃ (to prevent calcium oxide from absorbing water and deteriorating due to low temperature), take it out, grind it into powder to obtain CaO;

[0100] 3) uniformly mixing solution B, solution A and CaO, stirring at 80°C for 1 h, and then aging at 80°C for 48 h;

[0101] 4) The reaction solution in step 3) was centrifuged at 8000 rpm for 3 min, the separated sample was washed three times with DMF, and the filtered solid sample was dried at 90° C. for 24 h to obtain N-Ni1Co5 / CaO precursor;

[0102] 5) 2.0 g of the N-Ni1Co5 / CaO precursor prepared in step 3) was placed in a tube furnace and calcined at 500° C. in a nitrogen atmosphere for 2 h to obtain a black N-Ni1Co5 / CaO catalyst;

[0103] 6) Add 1.0 g of the N-Ni1Co5 / CaO catalyst prepared above, 10.0 g of isophthalonitrile, 8 mL of methanol, and 32 mL of toluene into a 100 mL lined autoclave, and react at 150° C. and 3.5 MPa for 4 h.

[0104] The conversion rate of isophthalonitrile was 100%, and the selectivity of meta-xylylenediamine was 99.2%.

[0105] Principle description:

[0106] The nitrogen-doped non-precious metal nanoparticles are prepared by high-temperature calcination using complex metal ions as precursors, with high dispersibility, simple preparation method, good repeatability, simple synthesis steps and low cost.

[0107] The introduction of nitrogen can effectively inhibit the deamination reaction, thereby increasing the yield of meta-phenylenediamine.

[0108] The prepared N-Ni1Co5 / CaO catalyst can achieve rapid and thorough separation of the catalyst and the reaction system by magnetic separation after the hydrogenation reaction of isophthalonitrile to prepare metaphenylenediamine, without the need for centrifugation, filtration or the like, which is conducive to the reuse of the catalyst, avoids the loss of the catalyst, and reduces the separation cost. When applied to the isophthalonitrile hydrogenation process, it can maintain an extremely high yield of metaphenylenediamine under mild reaction conditions.

[0109] The principles and implementation methods of the present invention are described herein using specific examples, and the description of the above embodiments is only used to help understand the method and core ideas of the present invention. The above are only preferred implementations of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, can make equivalent replacements or changes according to the technical solutions and inventive concepts of the present invention, which should be within the protection scope of the present invention.

Claims

1. A method for preparing a nitrogen-doped non-precious metal catalyst, characterized in that: The steps include: S1: ethylenediaminetetraacetic acid, triethylamine, nickel source and cobalt source are mixed in DMF solution and aged; S2: After centrifugation, drying and high-temperature calcination, the nitrogen-doped non-precious metal catalyst with an average particle size of 10 to 50 nm is obtained.

2. The preparation method according to claim 1, characterized in that: Step S1 specifically includes the following sub-steps: S1.1: vector preparation; S1.2: Add ethylenediaminetetraacetic acid and triethylamine into DMF to prepare solution A; S1.3: Dissolve the nickel source and the cobalt source in DMF to prepare solution B; S1.4: The carrier, solution A and solution B are mixed evenly and aged.

3. The preparation method according to claim 2, characterized in that: The carrier is one or more of calcium oxide, magnesium oxide, aluminum oxide, and zirconium oxide; The nickel source is nickel nitrate hexahydrate; The cobalt source is cobalt nitrate hexahydrate.

4. The preparation method according to claim 3, characterized in that: The carrier is a CaO carrier, and the preparation of the CaO carrier specifically includes the following steps: placing egg shells in a quartz boat with a cover, calcining them at high temperature in a tube furnace, and then taking them out after cooling to 80° C., thereby obtaining the CaO carrier.

5. The preparation method according to claim 4, characterized in that: The molar ratio of nickel nitrate hexahydrate, cobalt nitrate hexahydrate and CaO in the mixture of step S1.4 is (0.05-0.2):(0.05-0.2):

1.

6. The preparation method according to claim 3, characterized in that: The molar ratio of ethylenediaminetetraacetic acid, triethylamine, nickel nitrate hexahydrate and cobalt nitrate hexahydrate in the mixture of step S1.4 is (8-16):(8-16):1:

3.

7. The preparation method according to claim 6, characterized in that: In the mixture of step S1.4, the concentration of ethylenediaminetetraacetic acid is 0.4-1.0 mol / L, the concentration of triethylamine is 0.4-1.0 mol / L, the concentration of nickel nitrate hexahydrate is 0.025-0.05 mol / L, and the concentration of cobalt nitrate hexahydrate is 0.075-0.15 mol / L.

8. The preparation method according to claim 1, characterized in that: The molar ratio of nickel to cobalt in the nitrogen-doped non-precious metal catalyst is 1:5, and the mass proportion of nickel and cobalt is 20% to 60%; The aging time in step S1 is 18 to 72 hours; In step S2, the centrifugal speed is 8000 rpm, the centrifugal time is 3 min, and after centrifugation, the mixture is repeatedly washed with MDF 2 to 6 times; In step S2, the drying time is 12 to 34 hours and the drying temperature is 70 to 120° C.; The high temperature calcination method in step S2 is to increase the temperature to 500-900° C. at a heating rate of 2.5° C. / min in a nitrogen atmosphere and calcine for 1-6 hours.

9. An application of a nitrogen-doped non-precious metal catalyst, characterized in that: The preparation of m-xylylenediamine by hydrogenation of isophthalonitrile using a nitrogen-doped non-precious metal catalyst prepared by the preparation method according to any one of claims 1 to 8 comprises the following steps: S10: adding the nitrogen-doped non-precious metal catalyst, isophthalonitrile and solvent into a batch pressure reactor; S20: After replacing the air in the reactor with N2 and H2 for 2 to 4 times, H2 is introduced to stabilize the internal pressure at 0.5 MPa; S30: heating, stirring when the temperature reaches the first temperature, and increasing the internal pressure to the first pressure; S40: After the reaction is completed, the nitrogen-doped non-precious metal catalyst and the reaction liquid are separated, and the reaction liquid is the meta-xylylenediamine.

10. The use according to claim 9, characterized in that: The mass ratio of the nitrogen-doped non-precious metal catalyst, isophthalonitrile and solvent is 1:(10-30):(70-100); The solvent is a mixture of methanol and toluene, wherein the mass ratio of methanol to toluene is 1:4; In step S30, the first temperature is 80-160° C., and the first pressure is 1-10 MPa; The reaction time in step S40 is 1 to 10 hours.

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