A method for preparing aromatic diamines from aromatic nitro compounds

Abstract

The present invention provides a method for preparing aromatic diamines from aromatic nitro compounds, comprising the following steps: contacting the aromatic nitro compound with a catalyst under an H2 atmosphere, heating the catalyst to react, and obtaining the aromatic diamine; the catalyst is a nitrogen-doped carbon-supported non-precious metal bimetallic single-atom catalyst. The method for preparing aromatic diamines from aromatic nitro compounds provided by the present invention has the advantages of inexpensive and readily available catalyst raw materials, high catalyst activity and reusability, high conversion rate and product selectivity, mild reaction conditions, safe operation, and a clean process.

Description

Technical Field

[0001] The present invention relates to the technical field of organic chemical industry, in particular to a method for preparing aromatic diamines from aromatic nitro compounds. Background Art

[0002] Aromatic diamines are intermediates with a wide range of applications. Para-phenylenediamine can be used in the production of high-molecular-weight polymers such as para-aramid, polyamide-imide resins, and polyurethanes. It is also used in the production of azo disperse dyes, acid dyes, direct dyes, sulfur dyes, fur dyes, rubber antioxidants, and photographic developers. It is also a commonly used sensitive reagent for iron and copper testing. Meta-phenylenediamine is widely used in the production of meta-aramid, disperse dyes, reactive dyes, direct dyes, epoxy resin curing agents, cement accelerators, mordants, developers, petroleum additives, and in the pharmaceutical field. Ortho-phenylenediamine is used in the production of pesticides, fungicides, reducing dyes, cationic dyes, polymer stabilizers, heterocyclic compounds, photosensitive materials, surfactants, antifreeze agents, and copper corrosion inhibitors.

[0003] Traditional methods for producing aromatic diamines primarily involve the reduction of nitroarylamines or aromatic dinitro compounds in the presence of stoichiometric amounts of a reducing agent, such as iron powder. This generates significant amounts of waste and causes significant environmental pollution. Nitroarylamines or aromatic dinitro compounds can be hydrogenated to aromatic diamines in the presence of hydrogen and a precious metal catalyst, but the cost of precious metal catalysts is high. Hydrogenation of nitroarylamines or aromatic dinitro compounds to aromatic diamines using catalysts such as skeletal nickel is also possible, but the reaction conditions are harsh, requiring high reaction temperatures and pressures. Furthermore, skeletal nickel is highly flammable in air, resulting in poor operational safety. Summary of the Invention

[0004] In view of this, the technical problem to be solved by the present invention is to provide a method for preparing aromatic diamines from aromatic nitro compounds, wherein the catalyst raw materials are cheap and easily available, and the catalyst has good activity and reusability.

[0005] The present invention provides a method for preparing aromatic diamines from aromatic nitro compounds, comprising the following steps:

[0006] In an H2 atmosphere, the aromatic nitro compound is brought into contact with the catalyst and heated to react to obtain an aromatic diamine;

[0007] The catalyst is a nitrogen-doped carbon-supported non-noble metal bimetallic single-atom catalyst.

[0008] The following is the equation for the above reaction:

[0009]

[0010] Optionally, the aromatic nitro compound is selected from at least one of nitroaromatic amines and aromatic dinitro compounds.

[0011] Optionally, the aromatic nitro compound is selected from m-dinitrobenzene, o-dinitrobenzene, p-dinitrobenzene, o-nitroaniline, m-nitroaniline or p-nitroaniline.

[0012] According to the present invention, a catalyst is crucial for the reaction to proceed. Without a catalyst, the aromatic nitro compound does not undergo hydrogenation, and the aromatic diamine product cannot be obtained. Low catalyst activity results in very low feedstock conversion. The present invention utilizes a nitrogen-doped carbon-supported non-precious metal bimetallic single-atom catalyst as a hydrogenation catalyst.

[0013] Optionally, the bimetal in the nitrogen-doped carbon-supported non-noble metal bimetallic single-atom catalyst includes a metal component I and a metal component II;

[0014] Wherein, the metal component I is nickel, and the metal component II is selected from at least one of copper, cobalt, and chromium.

[0015] Optionally, the nitrogen-doped carbon-supported non-noble metal bimetallic single-atom catalyst is prepared according to the following method:

[0016] S1) mixing the non-noble metal salt I, the non-noble metal salt II, and the bidentate nitrogen-containing organic compound in a solvent, and heating to react to obtain a nitrogen-containing bimetallic complex;

[0017] The non-noble metal salt I is selected from nickel salts;

[0018] The non-noble metal salt II is selected from at least one of copper salt, cobalt salt and chromium salt;

[0019] S2) uniformly mixing the nitrogen-containing bimetallic complex and an alkali metal salt, and calcining the mixture under an inert atmosphere to obtain the nitrogen-doped carbon-supported non-noble metal bimetallic single atom catalyst.

[0020] Optionally, the nickel salt is selected from at least one of nickel hydrochloride, sulfate, nitrate and acetate.

[0021] Optionally, the copper salt is selected from at least one of copper hydrochloride, sulfate, nitrate and acetate.

[0022] Optionally, the cobalt salt is selected from at least one of hydrochloride, sulfate, nitrate and acetate of cobalt.

[0023] Optionally, the chromium salt is selected from at least one of chromium hydrochloride, sulfate, nitrate and acetate.

[0024] Optionally, the bidentate nitrogen-containing organic compound is at least one selected from o-phenanthroline, 2,2'-bipyridine, and disodium ethylenediaminetetraacetate.

[0025] Optionally, the molar ratio of the non-noble metal salt I to the non-noble metal salt II is 1:3 to 3:1.

[0026] Optionally, the molar ratio of the bidentate nitrogen-containing organic compound to the total amount of the non-noble metal salt I and the non-noble metal salt II is 50:1 to 100:1.

[0027] Optionally, the solvent is selected from ethanol aqueous solution.

[0028] Optionally, the volume concentration of the ethanol aqueous solution is 50% to 95%.

[0029] Optionally, the heating temperature is 40-70° C., and the heating time is 1-5 hours.

[0030] Optionally, in step S2), the alkali metal salt is selected from at least one of sodium carbonate, sodium bicarbonate, potassium carbonate, and potassium bicarbonate.

[0031] Optionally, the mass ratio of the nitrogen-containing bimetallic complex to the alkali metal salt is 1:2 to 1:5.

[0032] Optionally, the inert atmosphere is selected from at least one of nitrogen and argon.

[0033] Optionally, the calcination temperature is 800-1000° C., and the calcination time is 2-4 hours.

[0034] Optionally, the aromatic nitro compound is a solution of an aromatic nitro compound.

[0035] Optionally, the solvent of the solution is selected from methanol.

[0036] Optionally, the mass concentration of the solution of the aromatic nitro compound is 5% to 30%.

[0037] Optionally, the amount of the catalyst used is 2% to 4% by mass of the aromatic nitro compound.

[0038] Optionally, the pressure of H2 is 0.5-2 MPa.

[0039] Optionally, the reaction temperature is 60-100° C.; the reaction time is 1-2 h.

[0040] Compared to existing technologies, the present invention provides a method for preparing aromatic diamines from aromatic nitro compounds, comprising the following steps: contacting the aromatic nitro compound with a catalyst under an H2 atmosphere, heating the catalyst, and reacting to produce the aromatic diamine; the catalyst is a nitrogen-doped carbon-supported non-precious metal bimetallic single-atom catalyst. This method offers advantages such as readily available and inexpensive catalyst raw materials, high catalyst activity and reusability, high conversion rate and product selectivity, mild reaction conditions, safe operation, and a clean process. DETAILED DESCRIPTION

[0041] To further illustrate the present invention, the method for preparing aromatic diamines from aromatic nitro compounds provided by the present invention is described in detail below with reference to examples, but the present application is not limited to these examples.

[0042] Unless otherwise specified, the raw materials in the examples of this application were purchased from commercial sources. Unless otherwise specified, the testing methods were all conventional methods.

[0043] The conversion rate and selectivity in the examples of this application are calculated as follows:

[0044]

[0045]

[0046] Example 1

[0047] 1 mmol (0.24 g) of nickel (II) chloride hexahydrate, 1 mmol (0.17 g) of copper (II) chloride dihydrate, 0.1 mol (18.02 g) of o-phenanthroline and 100 mL of 75% ethanol were mixed, stirred at 60° C. for 3 h, and the solvent was evaporated and dried to obtain 18.28 g of nickel and copper complexes of o-phenanthroline. The complexes were evenly mixed with 91.40 g of sodium carbonate, calcined at 800° C. for 4 h under a N2 atmosphere, cooled to room temperature, washed with water, and dried to obtain 16.32 g of the nitrogen-doped carbon-supported nickel-copper bimetallic single-atom catalyst I.

[0048] Example 2

[0049] 1 mmol (0.28 g) of nickel (II) sulfate heptahydrate, 3 mmol (0.72 g) of cobalt (II) chloride hexahydrate, 0.4 mol (62.40 g) of 2,2'-bipyridine and 500 mL of 95% ethanol were mixed, stirred at 70°C for 1 h, and the solvent was evaporated and dried to obtain 62.66 g of nickel and cobalt complexes of 2,2'-bipyridine. The complexes were evenly mixed with 124.72 g of sodium bicarbonate, calcined at 1000°C for 2 h under N2 atmosphere, cooled to room temperature, washed with water, and dried to obtain 58.89 g of the nitrogen-doped carbon-supported nickel-cobalt bimetallic single-atom catalyst II.

[0050] Example 3

[0051] 3mmol (0.75g) of nickel (II) acetate tetrahydrate, 1mmol (0.17g) of chromium (III) nitrate nonahydrate, 0.2mol (67.24g) of disodium ethylenediaminetetraacetate and 500mL of 50% ethanol were mixed and stirred at 40°C for 5h. The solvent was evaporated and dried to obtain 67.46g of nickel and chromium complex of disodium ethylenediaminetetraacetate. The complex was evenly mixed with 134.48g of potassium carbonate, calcined at 900°C for 3h under N2 atmosphere, cooled to room temperature, washed with water, and dried to obtain 63.68g of the nitrogen-doped carbon-supported nickel-chromium bimetallic single-atom catalyst III.

[0052] Example 4

[0053] A 100g solution of 30% m-dinitrobenzyl alcohol and 0.6g of nitrogen-doped carbon-supported nickel-copper bimetallic single-atom catalyst I were added to a reactor. 2MPa of H₂ was introduced and stirred at 100°C for 1 hour. The mixture was then cooled to room temperature. GC-MS analysis showed 100% conversion of m-dinitrobenzene and 100% selectivity for m-phenylenediamine. After the reaction, the mixture was allowed to stand and then centrifuged to separate the nitrogen-doped carbon-supported nickel-copper bimetallic single-atom catalyst I for recycling.

[0054] Example 5

[0055] A 100g 20% ​​methanolic solution of p-nitroaniline and 0.4g of nitrogen-doped carbon-supported nickel-cobalt bimetallic single-atom catalyst II were added to a reactor, and the mixture was aerated with 0.5MPa of H₂ at 60°C for 2 hours. The mixture was then cooled to room temperature. GC-MS analysis showed 100% conversion of p-nitroaniline and 100% selectivity for p-phenylenediamine. After the reaction, the mixture was allowed to stand and then centrifuged to separate the nitrogen-doped carbon-supported nickel-cobalt bimetallic single-atom catalyst II for recycling.

[0056] Example 6

[0057] 100g of a 5% o-dinitrobenzyl alcohol solution and 0.2g of a nitrogen-doped carbon-supported nickel-chromium bimetallic single-atom catalyst III were added to a reactor. 1MPa of H₂ was introduced and stirred at 80°C for 1 hour. The mixture was then cooled to room temperature. GC-MS analysis showed 100% conversion of m-dinitrobenzene and 100% selectivity for o-phenylenediamine. After the reaction, the mixture was allowed to stand and then centrifuged to separate the nitrogen-doped carbon-supported nickel-chromium bimetallic single-atom catalyst III for recycling.

[0058] Example 7

[0059] Example 7 is similar to Example 4, except that a different catalyst was used. Other reaction conditions were the same as those in Example 4. Example 7 used the nitrogen-doped carbon-supported nickel-copper bimetallic single-atom catalyst I centrifuged after the reaction in Example 4. The results showed a 100% conversion of m-dinitrobenzene and a 100% selectivity for m-phenylenediamine. Even after the catalyst was recycled 10 times, the conversion of m-dinitrobenzene and the selectivity for m-phenylenediamine remained 100%.

[0060] Comparative Examples 1-3

[0061] Comparative Examples 1-3 are similar to Example 1, except that different types of metal salts are used in preparing the catalysts. Other preparation conditions are the same as those in Example 1.

[0062] The difference between Comparative Example 1 and Example 1 is that only 1 mmol (0.24 g) of nickel (II) chloride hexahydrate was used in the preparation of the catalyst, and copper (II) chloride dihydrate was not used, resulting in 16.01 g of nitrogen-doped carbon-supported nickel single-atom catalyst IV.

[0063] The difference between Comparative Example 2 and Example 1 is that only 1 mmol (0.17 g) of copper (II) chloride dihydrate was used in the preparation of the catalyst, and nickel (II) chloride hexahydrate was not used. As a result, 15.86 g of nitrogen-doped carbon-supported copper single-atom catalyst V was obtained.

[0064] The difference between Comparative Example 3 and Example 1 is that 1 mmol (0.24 g) of nickel (II) chloride hexahydrate and 1 mmol (0.42 g) of iron (III) sulfate nonahydrate were used to prepare the catalyst, resulting in 16.36 g of nitrogen-doped carbon-supported nickel-iron bimetallic single-atom catalyst VI.

[0065] Comparative Examples 4-7

[0066] Comparative Examples 4-7 are similar to Example 4, except that different catalysts are used and other reaction conditions are the same as Example 4.

[0067] The difference between Comparative Example 4 and Example 4 is that Comparative Example 4 uses 0.6 g of nitrogen-doped carbon-supported nickel single-atom catalyst IV, and the conversion rate of m-dinitrobenzene is 46%.

[0068] The difference between Comparative Example 5 and Example 4 is that Comparative Example 5 uses 0.6 g of nitrogen-doped carbon-supported copper single-atom catalyst V, and the conversion rate of m-dinitrobenzene is 15%.

[0069] The difference between Comparative Example 6 and Example 4 is that Comparative Example 6 uses a mixture of 0.3 g of nitrogen-doped carbon-supported nickel single-atom catalyst IV and 0.3 g of nitrogen-doped carbon-supported copper single-atom catalyst V as a catalyst, and the conversion rate of m-dinitrobenzene is 48%.

[0070] The difference between Comparative Example 7 and Example 4 is that Comparative Example 7 uses 0.6 g of nitrogen-doped carbon-supported nickel-iron bimetallic single-atom catalyst VI, and the conversion rate of m-dinitrobenzene is 50%.

[0071] The results of comparative examples 4-7 show that in the reaction described in the present invention, the metal component supported by nitrogen-doped carbon has a great influence on the catalytic activity of the non-precious metal single-atom catalyst supported by nitrogen-doped carbon. When nitrogen-doped carbon alone supports single-atom nickel or copper, the conversion rate of m-dinitrobenzene is low; when a mixture of single-atom nickel supported by nitrogen-doped carbon and single-atom copper supported by nitrogen-doped carbon is used as a catalyst, the result is not much different from that of the nitrogen-doped carbon-supported single-atom nickel catalyst; when a nickel-iron bimetallic single-atom catalyst supported by nitrogen-doped carbon is used, the result is not much different from that of the nitrogen-doped carbon-supported single-atom nickel catalyst.

[0072] Combined with the results of the examples, it is speculated that in the nitrogen-doped carbon-supported non-noble metal bimetallic single-atom catalyst of the present invention, the doped nitrogen atoms coordinate with the metal atoms, stabilizing the metal atoms. Furthermore, the interaction between hydrogen and the electron-rich nitrogen facilitates hydrogen adsorption on the metal surface and its activation by the metal. The nitrogen-doped carbon-supported single-atom nickel synergistically catalyzes with single-atom copper, cobalt, and chromium atoms, enhancing the catalyst's reactivity.

[0073] In summary, the present invention relates to a method for producing aromatic diamines by contacting an aromatic nitro compound solution with a catalyst in the presence of H2 and heating the reaction. A nitrogen-doped carbon-supported non-precious metal bimetallic single-atom catalyst is used, wherein the metal component I is nickel and the metal component II is at least one of copper, cobalt, and chromium. The method achieves 100% conversion of the aromatic nitro compound and selectivity for the aromatic diamines, and the catalyst maintains its catalytic activity even after 10 cycles. This method has the advantages of readily available and inexpensive catalyst raw materials, good catalyst activity and reusability, high conversion and product selectivity, mild reaction conditions, safe operation, and a clean process.

[0074] The above embodiments are only intended to help understand the method and core concept of the present invention. It should be noted that, without departing from the principles of the present invention, a number of improvements and modifications may be made to the present invention by those skilled in the art, and such improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing aromatic diamines from aromatic nitro compounds, characterized in that: The following steps are involved: In an H2 atmosphere, the aromatic nitro compound is brought into contact with the catalyst and heated to react to obtain an aromatic diamine; The catalyst is a nitrogen-doped carbon-supported non-noble metal bimetallic single-atom catalyst; The aromatic nitro compound is selected from at least one of nitroaromatic amines and aromatic dinitro compounds; The bimetal in the nitrogen-doped carbon-supported non-noble metal bimetallic single-atom catalyst includes a metal component I and a metal component II; Wherein, the metal component I is nickel, and the metal component II is selected from at least one of copper, cobalt, and chromium; The nitrogen-doped carbon-supported non-noble metal bimetallic single-atom catalyst is prepared according to the following method: S1) mixing the non-noble metal salt I, the non-noble metal salt II, and the bidentate nitrogen-containing organic compound in a solvent, and heating to react to obtain a nitrogen-containing bimetallic complex; S2) uniformly mixing the nitrogen-containing bimetallic complex and an alkali metal salt, and calcining under an inert atmosphere to obtain the nitrogen-doped carbon-supported non-noble metal bimetallic single atom catalyst; The bidentate nitrogen-containing organic compound is selected from at least one of o-phenanthroline, 2,2'-bipyridine, and disodium ethylenediaminetetraacetate; The amount of the catalyst used is 2% to 4% of the mass of the aromatic nitro compound; The reaction temperature for preparing aromatic diamine from aromatic nitro compound is 60-100° C. and the reaction time is 1-2 hours.

2. The method according to claim 1, characterized in that The nickel salt is selected from at least one of nickel hydrochloride, sulfate, nitrate, and acetate; The copper salt is selected from at least one of copper hydrochloride, sulfate, nitrate, and acetate; The cobalt salt is selected from at least one of cobalt hydrochloride, sulfate, nitrate, and acetate; The chromium salt is selected from at least one of chromium hydrochloride, sulfate, nitrate and acetate.

3. The method according to claim 1, characterized in that The molar ratio of the non-noble metal salt I and the non-noble metal salt II is 1:3 to 3:1; The molar ratio of the bidentate nitrogen-containing organic compound to the total amount of the non-noble metal salt I and the non-noble metal salt II is 50:1 to 100:1; The solvent is an ethanol aqueous solution; The volume concentration of the ethanol aqueous solution is 50% to 95%; The heating temperature is 40-70° C., and the heating time is 1-5 hours.

4. The method according to claim 1, wherein In the step S2), the alkali metal salt is selected from at least one of sodium carbonate, sodium bicarbonate, potassium carbonate, and potassium bicarbonate; The inert atmosphere is selected from at least one of nitrogen and argon; The mass ratio of the nitrogen-containing bimetallic complex to the alkali metal salt is 1:2 to 1:5; The calcination temperature is 800-1000° C., and the calcination time is 2-4 hours.

5. The method according to claim 1, wherein The aromatic nitro compound is a solution of an aromatic nitro compound; The solvent of the solution is selected from methanol; The mass concentration of the solution of the aryl nitro compound is 5% to 30%.

6. The method according to claim 1, characterized in that The pressure of H2 is 0.5-2 MPa.

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