A method for the preparation of arylamines by transfer hydrogenation

Abstract

The application belongs to the technical field of preparation of catalytic materials and organic synthesis, and particularly relates to a method for preparing arylamine compounds through hydrogen transfer, which comprises the following steps: mixing cellulose and dealkali lignin according to a certain mass ratio to serve as carbon precursor material; or crushing waste straw to prepare powder for treatment to serve as carbon precursor material; uniformly mixing the carbon precursor material and P2O5 in different mass ratios, transferring the mixture to a hydrothermal kettle, and performing reaction at a certain temperature; cooling to room temperature after the reaction is completed; vacuum drying to obtain primary carbon material; transferring the corundum boat containing the primary carbon material to a tube furnace, performing high-temperature pyrolysis at a controllable temperature, and then naturally cooling to room temperature to obtain biocarbon catalytic material; adding nitrobenzene and nitrogen heterocyclic compounds and a certain amount of water as a solvent into a pressure reaction tube, and then adding a proper amount of prepared biocarbon material as a catalyst to obtain aniline and nitrogen-containing aromatic heterocyclic compounds.

Description

Technical Field

[0001] This invention belongs to the field of catalytic material preparation and organic synthesis technology, specifically a method for preparing aromatic amine compounds by hydrogen transfer. Background Technology

[0002] Aromatic amines, as the most common and important raw materials and intermediates in organic synthesis, have seen their catalytic synthesis and preparation become one of the most important research topics in academia and industry. In recent years, transition metal-catalyzed hydrogen transfer reactions have attracted widespread attention in the field of green catalysis research due to their high atom economy, good chemical specificity, and clean conversion in the synthesis and preparation of aromatic amines. However, to date, the active components of catalysts in most chemical reactions involving catalytic hydrogen transfer are generally metals, predominantly transition metals. This is because transition metals have a relatively large number of empty d or f orbitals that can bond with substrate molecules, forming transition states with lower energy barriers, thereby accelerating the chemical reaction. Furthermore, catalytically active sites formed by metals can also directly interact with hydrogen donors, completing the hydrogen transfer process by forming active metal hydrides (MH). However, carbon nanomaterials are generally considered to lack empty orbitals and are unlikely to form active hydrides. Therefore, without the synergistic activation of co-catalysts or reaction promoters, it is difficult to achieve catalytic hydrogen transfer using only carbon nanomaterials. Furthermore, the preparation and use of transition metal catalytic materials face challenges such as complex preparation processes, high costs, harsh conditions, poor stability, high toxicity, and cross-contamination caused by the leaching of trace metal ions in aqueous reactions. Therefore, from the perspective of green chemistry and the circular economy, it is essential to construct simple, efficient, and low-cost heterogeneous non-metallic catalytic systems and achieve the green catalytic preparation of nitrogen-containing aromatic heterocyclic compounds and aniline compounds through the catalytic hydrogenation of nitrogen-containing heterocyclic and nitrobenzene compounds.

[0003] In recent years, catalytic hydrogen transfer has attracted much attention in the field of green chemistry research and application due to its advantages such as simple operation, high atom economy, and environmental friendliness. Among these, the efficient and green one-pot catalytic preparation of aniline and nitrogen-containing aromatic heterocyclic compounds via the catalytic hydrogen transfer of nitrobenzenes and nitrogen-containing heterocyclic compounds under water-based solvent conditions has been reported. Its green conversion process and generally mild aqueous phase reaction conditions embody the principles of green chemistry. However, despite the many advantages shown by the catalytic materials in the reported catalytic synthesis strategies, there are still significant drawbacks in preparation and application. These include the use of expensive nitrogen-containing materials as carbon precursors and large amounts of metal salts as active precursors; moreover, the cumbersome preparation process, difficulty in controlling the actual metal loading, and poor stability, resulting in high cost and poor durability for these catalytic materials. In particular, the potential for cross-contamination due to metal leaching during the reaction further limits the industrial development of these catalytic materials. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for preparing aromatic amine compounds by hydrogenation, which has the advantages of good economic benefits, simple and green preparation process, good catalytic performance, and stable structure.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A method for preparing aromatic amine compounds by hydrogenation, characterized by comprising the following steps: Step 1: Mix cellulose and lignin (de-alkali) at a certain mass ratio to use as carbon precursor material; or, prepare waste straw into powder using a crusher (passing through a 400-mesh stainless steel sieve), treat the straw powder with a 5 wt% NaOH aqueous solution, and then slowly add HCl solution dropwise under vigorous stirring until the pH is 5. Centrifuge the mixture, wash it with a large amount of deionized water until neutral, centrifuge it again, and vacuum dry the treated straw powder to use as carbon precursor material. Step 2: The carbon precursor material obtained in Step 1 is mixed with P2O5 at different mass ratios and then transferred to a hydrothermal reactor and reacted at a certain temperature. After the reaction is completed, it is cooled to room temperature, then washed multiple times with deionized water and methanol until neutral, and then vacuum dried to obtain the primary carbon material. Step 3: Transfer the corundum boat containing the primary carbon material obtained in step 2 to a tube furnace, use nitrogen as a protective gas, carry out high-temperature pyrolysis at a controlled temperature, and then allow it to cool naturally to room temperature to obtain biocarbon catalytic material. Step 4: Add nitrobenzene and nitrogen heterocyclic compounds and a certain amount of water as solvent to a pressure reaction tube, and then add an appropriate amount of biochar material prepared in step 3 as catalyst. Under nitrogen conditions, react at a certain temperature for 8-36 hours to obtain aniline and nitrogen-containing aromatic heterocyclic compounds.

[0006] Preferably, in step 1, the mass ratio of cellulose to lignin (de-alkali) is 0.5 to 8:1.

[0007] Preferably, in step 1, the mass ratio of straw powder before impurity removal to 5 wt% NaOH aqueous solution is 1:20-50, the stirring time is 0.2-1h, and the treated straw powder is vacuum dried at 25-60℃ to obtain the corresponding carbon precursor material.

[0008] Preferably, in step 1, the waste straw is one of wheat straw, corn straw, rice straw, and soybean straw.

[0009] Preferably, in step 2, the mass ratio of carbon precursor material to P2O5 in the hydrothermal reactor is 1:5-8, the vacuum drying temperature of the primary carbon material is 25-60°C, and the reaction temperature in the hydrothermal reactor is 100-150°C. o C, the reaction time is 1 to 8 hours.

[0010] Preferably, in step 3, the heating rate of the tubular furnace is 5-10℃ / min, the preset end temperature of the furnace is controlled at 600-950℃, and after the controllable high-temperature pyrolysis end temperature in the tubular furnace reaches the preset temperature, it is maintained for 2-4 hours.

[0011] Preferably, in step 3, a cone-shaped quinone and phenol active unit with hydrogen cycling performance is formed in the preparation of the biocarbon catalytic material.

[0012] Preferably, in step 4, the molar ratio of nitrobenzene compounds to nitrogen heterocyclic compounds is 1:1.5-3, the amount of catalyst participating in the reaction is 50-100 mg / mmol of nitrobenzene compounds, the reaction temperature of the catalytic reaction system is 90-150 °C, the solvent in the catalytic reaction is deionized water, and the catalytic reaction time is 8-36 h.

[0013] Preferably, the nitrogen heterocyclic compound is one of tetrahydroquinoline compounds, tetrahydroisoquinoline compounds, tetrahydroquinoxaloline compounds, and indoline compounds.

[0014] As a preferred option, the catalytic reaction equation is: .

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. The catalytic material described in this invention can promote hydrogen transfer between nitrobenzene and nitrogen-containing heterocyclic compounds through a hydrogen cycling mechanism between active quinone and phenolic units formed within the material in deionized water, thereby achieving a simple, efficient, green, and low-cost catalytic preparation of aniline and nitrogen-containing aromatic heterocyclic compounds. Through 50 catalytic cycle experiments, it was found that the activity loss of the catalytic material did not exceed 5%.

[0016] 2. This invention breaks through the framework of metal-based catalytic systems based on the above reactions; 3. The carbon precursor materials of this invention are abundant, green, and have low preparation costs; 4. The preparation method of the biocarbon catalytic material of the present invention is simple and controllable; 5. The biochar catalytic material of this invention does not cause cross-contamination when used in an aqueous system; 6. The biocarbon catalytic material of this invention has good performance and stability; it has potential industrial development value. Attached Figure Description

[0017] Figure 1 This is a schematic diagram illustrating the preparation of the biocarbon catalytic material in this invention. Detailed Implementation

[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. It should be understood that the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Example 1

[0020] Cellulose and lignin (de-alkali-treated) were mixed at a mass ratio of 2:1 to serve as a carbon precursor material (total mass 2g). This carbon precursor material was mixed with P2O5 at a mass ratio of 1:5 and ground uniformly. The mixture was then transferred to a 100 mL hydrothermal reactor, purged with nitrogen, and reacted at 100 °C for 6 h, followed by cooling to room temperature. The resulting primary carbon material was washed multiple times with a mixture of methanol and deionized water until neutral, and the solid material was centrifuged. Subsequently, it was vacuum dried at 60 °C to obtain the primary carbon material. The corundum boat containing the primary carbon material was transferred to a tube furnace and subjected to high-temperature pyrolysis under controlled temperature with nitrogen as the protective gas (heating rate controlled at 5 °C / min until the temperature reached 850 °C, and held at this temperature for 2 h). Afterward, it was naturally cooled to room temperature to obtain the biocarbon catalyst material. Subsequently, 1 mmol of nitrobenzene, 1.5 mmol of 1,2,3,4-tetrahydroquinoline, 2 mL of deionized water, and 50 mg of the obtained biochar catalyst were added to 15 mL pressure tubes, purged with nitrogen for 2 min, and the tubes were sealed with PTFE threaded caps. The tubes were then incubated at 140 °C. o The reaction was stirred at C for 14 h. The separation yields of aniline and quinoline were 84% and 82%, respectively.

[0021] Example 2

[0022] Cellulose and lignin (de-alkali-treated) were mixed at a mass ratio of 3:1 as a carbon precursor material (total mass 2g). This carbon precursor material was mixed with P2O5 at a mass ratio of 1:5 and ground uniformly. The mixture was transferred to a 100 mL hydrothermal reactor, purged with nitrogen, and reacted at 150 °C for 6 h, then cooled to room temperature. The resulting primary carbon material was washed several times with a mixture of methanol and deionized water until neutral, and the solid material was centrifuged and then vacuum dried at 60 °C to obtain the primary carbon material. The corundum boat containing the primary carbon material was transferred to a tube furnace and subjected to high-temperature pyrolysis under controlled temperature with nitrogen as the protective gas (heating rate controlled at 5 °C / min until the temperature reached 850 °C, and held at this temperature for 2 h). Afterward, it was naturally cooled to room temperature to obtain the biocarbon catalyst material. Subsequently, 1 mmol of nitrobenzene, 1.5 mmol of 1,2,3,4-tetrahydroquinoline, 2 mL of deionized water, and 50 mg of the obtained biochar catalyst were added to 15 mL pressure tubes, purged with nitrogen for 2 min, and the tubes were sealed with PTFE threaded caps. The tubes were then heated to 140 °C. o The reaction was stirred at C for 14 h. The separation yields of aniline and quinoline were 88% and 86%, respectively.

[0023] Example 3

[0024] Cellulose and lignin (de-alkali-treated) were mixed at a mass ratio of 4:1 as a carbon precursor material (total mass 5g). This carbon precursor material was mixed with P2O5 at a mass ratio of 1:6 and ground uniformly. The mixture was transferred to a 250 mL hydrothermal reactor, purged with nitrogen, and reacted at 100 °C for 6 h, then cooled to room temperature. The resulting primary carbon material was washed multiple times with a mixture of methanol and deionized water until neutral, and the solid material was centrifuged and then vacuum dried at 60 °C to obtain the primary carbon material. The corundum boat containing the primary carbon material was transferred to a tube furnace and subjected to high-temperature pyrolysis under controlled temperature with nitrogen as the protective gas (heating rate controlled at 7 °C / min until the temperature reached 850 °C, and held at this temperature for 2 h). Afterward, it was naturally cooled to room temperature to obtain the biocarbon catalyst material. Subsequently, 1 mmol of nitrobenzene, 1.5 mmol of 1,2,3,4-tetrahydroquinoline, 2 mL of deionized water, and 50 mg of the obtained biochar catalyst were added to 15 mL pressure tubes, purged with nitrogen for 2 min, and the tubes were sealed with PTFE threaded caps. The tubes were then heated to 140 °C. o The reaction was stirred at C for 14 h. The yields of aniline and quinoline were 82% and 78%, respectively.

[0025] Example 4

[0026] Cellulose and lignin (de-alkali-treated) were mixed at a mass ratio of 5:1 as a carbon precursor material (total mass 10 g). This carbon precursor material was mixed with P2O5 at a mass ratio of 1:6 and ground uniformly. The mixture was transferred to a 500 mL hydrothermal reactor, purged with nitrogen, and reacted at 120 °C for 6 h, then cooled to room temperature. The resulting primary carbon material was washed several times with a mixture of methanol and deionized water until neutral, and the solid material was centrifuged and then vacuum dried at 40 °C to obtain the primary carbon material. The corundum boat containing the primary carbon material was transferred to a tube furnace and subjected to high-temperature pyrolysis at a controlled temperature using nitrogen as a protective gas (heating rate controlled at 6 °C / min until the temperature reached 700 °C, and held at this temperature for 3 h). Afterward, it was naturally cooled to room temperature to obtain the biocarbon catalyst material. Subsequently, 1 mmol of nitrobenzene, 1.5 mmol of 1,2,3,4-tetrahydroquinoline, 2 mL of deionized water, and 50 mg of the obtained biochar catalyst were added to 15 mL pressure tubes, purged with nitrogen for 2 min, and the tubes were sealed with PTFE threaded caps. The tubes were then heated to 140 °C. o The reaction was stirred at C for 14 h. The yields of aniline and quinoline were 86% and 82%, respectively.

[0027] Example 5

[0028] Cellulose and lignin (de-alkali-treated) were mixed at a mass ratio of 8:1 as a carbon precursor material (total mass 10 g). This carbon precursor material was mixed with P2O5 at a mass ratio of 1:6 and ground uniformly. The mixture was transferred to a 500 mL hydrothermal reactor, purged with nitrogen, and reacted at 100 °C for 6 h, then cooled to room temperature. The resulting primary carbon material was washed several times with a mixture of methanol and deionized water until neutral, and the solid material was centrifuged and then vacuum dried at 40 °C to obtain the primary carbon material. The corundum boat containing the primary carbon material was transferred to a tube furnace and subjected to high-temperature pyrolysis at a controlled temperature using nitrogen as a protective gas (heating rate controlled at 5 °C / min until the temperature reached 750 °C, and held at this temperature for 2 h). Afterward, it was naturally cooled to room temperature to obtain the biocarbon catalytic material. Subsequently, 1 mmol of nitrobenzene, 1.5 mmol of 1,2,3,4-tetrahydroquinoline, 2 mL of deionized water, and 50 mg of the obtained biochar catalyst were added to 15 mL pressure tubes, purged with nitrogen for 2 min, and the tubes were sealed with PTFE threaded caps. The tubes were then heated to 140 °C. o The reaction was stirred at C for 14 h. The yields of aniline and quinoline were 81% and 80%, respectively.

[0029] Example 6

[0030] Waste wheat straw was dried and pulverized into powder using a crusher (passing through a 400-mesh stainless steel sieve). 5g of coarse wheat straw powder was added to 150ml of 5 wt% NaOH aqueous solution and stirred for 0.5h. Then, HCl solution was slowly added dropwise under vigorous stirring until the pH reached 5. The mixture was centrifuged and washed repeatedly with a large amount of deionized water until neutral. The treated wheat straw powder was then centrifuged again and vacuum dried at 60℃ to obtain a carbon precursor material. 2g of this carbon precursor material was mixed with P2O5 at a mass ratio of 1:6 and ground evenly. The mixture was transferred to a 100mL hydrothermal reactor, purged with nitrogen, and reacted at 100℃ for 6h, then cooled to room temperature. The resulting primary carbon material was washed repeatedly with a mixture of methanol and deionized water until neutral, and the solid material was centrifuged and then vacuum dried at 40℃ to obtain the primary carbon material. A corundum boat containing primary carbon material was transferred to a tube furnace and subjected to high-temperature pyrolysis under controlled temperature using nitrogen as a protective gas (heating rate controlled at 5℃ / min until the temperature reached 750℃, and maintained at that temperature for 2 h). The material was then allowed to cool naturally to room temperature to obtain the biochar catalyst. Subsequently, 1 mmol of nitrobenzene, 1.5 mmol of 1,2,3,4-tetrahydroquinoline, 2 mL of deionized water, and 50 mg of the obtained biochar catalyst were added to 15 mL pressure tubes, purged with nitrogen for 2 min, and the tubes were sealed with PTFE threaded caps. The furnace was then heated to 140℃. oThe reaction was stirred at C for 18 h. The separation yields of aniline and quinoline were 88% and 90%, respectively.

[0031] Example 7

[0032] Waste wheat straw was dried and pulverized into powder using a crusher (passing through a 400-mesh stainless steel sieve). 10g of coarse wheat straw powder was added to 300ml of 5 wt% NaOH aqueous solution and stirred for 0.5h. Then, HCl solution was slowly added dropwise under vigorous stirring until the pH reached 5. The mixture was centrifuged and washed repeatedly with a large amount of deionized water until neutral. The treated wheat straw powder was then centrifuged again and vacuum dried at 60℃ to obtain a carbon precursor material. 5g of this carbon precursor material was mixed with P2O5 at a mass ratio of 1:5 and ground evenly. The mixture was transferred to a 250mL hydrothermal reactor, purged with nitrogen, and reacted at 120℃ for 6h, then cooled to room temperature. The resulting primary carbon material was washed repeatedly with a mixed solution of methanol and deionized water until neutral, and the solid material was centrifuged and then vacuum dried at 40℃ to obtain the primary carbon material. A corundum boat containing primary carbon material was transferred to a tube furnace and subjected to high-temperature pyrolysis under controlled temperature using nitrogen as a protective gas (heating rate controlled at 5℃ / min until the temperature reached 850℃, and held at that temperature for 2 h). The furnace was then allowed to cool naturally to room temperature to obtain the biochar catalyst. Subsequently, 1 mmol of nitrobenzene, 1.5 mmol of 1,2,3,4-tetrahydroquinoline, 2 mL of deionized water, and 50 mg of the obtained biochar catalyst were added to 15 mL pressure tubes, purged with nitrogen for 2 min, and the tubes were sealed with PTFE threaded caps. The furnace was then heated to 140℃. o The reaction was stirred at C for 16 h. The yields of aniline and quinoline were 80% and 77%, respectively.

[0033] Example 8

[0034] Waste wheat straw was dried and pulverized into powder using a crusher (passing through a 400-mesh stainless steel sieve). 10g of coarse wheat straw powder was added to 300ml of 5 wt% NaOH aqueous solution and stirred for 0.5h. Then, HCl solution was slowly added dropwise under vigorous stirring until the pH reached 5. The mixture was centrifuged and washed repeatedly with a large amount of deionized water until neutral. The treated wheat straw powder was then centrifuged again and vacuum dried at 60℃ to obtain a carbon precursor material. 5g of this carbon precursor material was mixed with P2O5 at a mass ratio of 1:8 and ground evenly. The mixture was transferred to a 250mL hydrothermal reactor, purged with nitrogen, and reacted at 100℃ for 6h, then cooled to room temperature. The resulting primary carbon material was washed repeatedly with a mixed solution of methanol and deionized water until neutral, and the solid material was centrifuged and then vacuum dried at 25℃ to obtain the primary carbon material. A corundum boat containing primary carbon material was transferred to a tube furnace and subjected to high-temperature pyrolysis under controlled temperature using nitrogen as a protective gas (heating rate controlled at 5℃ / min until the temperature reached 750℃, and maintained at that temperature for 3 h). The furnace was then allowed to cool naturally to room temperature to obtain the biochar catalyst. Subsequently, 1 mmol of p-bromonitrobenzene, 1.5 mmol of 1,2,3,4-tetrahydroquinoline, 2 mL of deionized water, and 50 mg of the obtained biochar catalyst were added to 15 mL pressure tubes, respectively. After purging with nitrogen for 2 min, the tubes were sealed with PTFE threaded caps and heated to 150℃. o The reaction was stirred at C for 16 h. The products p-bromoaniline and quinoline were obtained in separate yields of 78% and 81%, respectively.

[0035] Example 9

[0036] Waste soybean straw was dried and pulverized into powder using a crusher (passing through a 400-mesh stainless steel sieve). 10g of coarse soybean straw powder was added to a 5 wt% NaOH aqueous solution (300ml) and stirred for 0.5h. Then, HCl solution was slowly added dropwise under vigorous stirring until the pH reached 5. The mixture was centrifuged and washed repeatedly with a large amount of deionized water until neutral. The treated soybean straw powder was then centrifuged again and vacuum dried at 60℃ to obtain a carbon precursor material. 10g of this carbon precursor material was mixed with P2O5 at a mass ratio of 1:6 and ground evenly. The mixture was transferred to a 500mL hydrothermal reactor, purged with nitrogen, and reacted at 100℃ for 6h, then cooled to room temperature. The resulting primary carbon material was washed repeatedly with a mixed solution of methanol and deionized water until neutral, and the solid material was centrifuged and then vacuum dried at 40℃ to obtain the primary carbon material. A corundum boat containing primary carbon material was transferred to a tube furnace and subjected to high-temperature pyrolysis under controlled temperature using nitrogen as a protective gas (heating rate controlled at 5℃ / min until the temperature reached 900℃, and maintained at that temperature for 2 h). The furnace was then allowed to cool naturally to room temperature to obtain the biochar catalyst. Subsequently, 1 mmol of p-chloronitrobenzene, 1.5 mmol of 1,2,3,4-tetrahydroquinoline, 2 mL of deionized water, and 50 mg of the obtained biochar catalyst were added to 15 mL pressure tubes, respectively. After purging with nitrogen for 2 min, the tubes were sealed with PTFE threaded caps and heated to 150℃. o The reaction was stirred at C for 18 h. The products p-chloroaniline and quinoline were separated in yields of 80% and 82%, respectively.

[0037] Example 10

[0038] Waste corn stalks were dried and pulverized into powder using a crusher (passing through a 400-mesh stainless steel sieve). 5g of coarse corn stalk powder was added to 150ml of 5 wt% NaOH aqueous solution and stirred for 0.5h. Then, HCl solution was slowly added dropwise under vigorous stirring until the pH reached 5. The mixture was centrifuged and washed repeatedly with a large amount of deionized water until neutral. The treated corn stalk powder was then centrifuged again and vacuum dried at 60℃ to obtain a carbon precursor material. 2g of this carbon precursor material was mixed with P2O5 at a mass ratio of 1:6 and ground evenly. The mixture was transferred to a 100mL hydrothermal reactor, purged with nitrogen, and reacted at 100℃ for 6h, then cooled to room temperature. The resulting primary carbon material was washed repeatedly with a mixture of methanol and deionized water until neutral, and the solid material was centrifuged and then vacuum dried at 40℃ to obtain the primary carbon material. A corundum boat containing primary carbon material was transferred to a tube furnace and subjected to high-temperature pyrolysis under controlled temperature using nitrogen as a protective gas (heating rate controlled at 5℃ / min until the temperature reached 850℃, and maintained at that temperature for 2 h). The furnace was then allowed to cool naturally to room temperature to obtain biochar catalyst material. Subsequently, 1 mmol of nitrobenzene, 1.5 mmol of 6-methyl-1,2,3,4-tetrahydroquinoline, 2 mL of deionized water, and 50 mg of the obtained biochar catalyst material were added to 15 mL pressure tubes, respectively. After purging with nitrogen for 2 min, the tube openings were sealed with PTFE threaded caps and heated to 150℃. o The reaction was stirred at C for 18 h. The yields of aniline and 6-methylquinoline were 71% and 69%, respectively.

[0039] Example 11

[0040] Waste corn stalks were dried and pulverized into powder using a crusher (passing through a 400-mesh stainless steel sieve). 10g of coarse corn stalk powder was added to a 5 wt% NaOH aqueous solution (300ml) and stirred for 0.5h. Then, HCl solution was slowly added dropwise under vigorous stirring until the pH reached 5. The mixture was centrifuged and washed repeatedly with a large amount of deionized water until neutral. The treated corn stalk powder was then centrifuged again and vacuum dried at 60℃ to obtain a carbon precursor material. 2g of this carbon precursor material was mixed with P2O5 at a mass ratio of 1:5 and ground evenly. The mixture was transferred to a 100mL hydrothermal reactor, purged with nitrogen, and reacted at 150℃ for 6h, then cooled to room temperature. The resulting primary carbon material was washed repeatedly with a mixture of methanol and deionized water until neutral, and the solid material was centrifuged and then vacuum dried at 40℃ to obtain the primary carbon material. A corundum boat containing primary carbon material was transferred to a tube furnace and subjected to high-temperature pyrolysis under controlled temperature using nitrogen as a protective gas (heating rate controlled at 5℃ / min until the temperature reached 800℃, and maintained at that temperature for 2 h). The furnace was then allowed to cool naturally to room temperature to obtain biochar catalyst material. Subsequently, 1 mmol of nitrobenzene, 1.5 mmol of 1,2,3,4-tetrahydro-6-hydroxyquinoline, 2 mL of deionized water, and 50 mg of the obtained biochar catalyst material were added to 15 mL pressure tubes, respectively. After purging with nitrogen for 2 min, the tube openings were sealed with PTFE threaded caps and heated to 150℃. o The reaction was stirred at C for 18 h. The yields of aniline and 6-hydroxyquinoline were 80% and 76%, respectively.

[0041] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Any MnO2 nanoparticles prepared by those skilled in the art under the guidance of this application, without departing from the spirit and scope of the claims, are within the protection scope of this application.

Claims

1. A method for preparing aromatic amine compounds by hydrogenation, characterized in that, Includes the following steps: Step 1: Mix cellulose and dealkalized lignin in a certain mass ratio to use as carbon precursor material; or, prepare waste straw into powder by crushing machine, pass the powder through a 400-mesh stainless steel sieve, treat the straw powder with 5 wt% NaOH aqueous solution, and then slowly add HCl solution dropwise under vigorous stirring until the pH is 5. Centrifuge the mixture, wash it with a large amount of deionized water until neutral, centrifuge it again, and vacuum dry the treated straw powder to use as carbon precursor material. Step 2: The carbon precursor material obtained in Step 1 is mixed with P2O5 at different mass ratios and then transferred to a hydrothermal reactor and reacted at a certain temperature. After the reaction is completed, it is cooled to room temperature, then washed multiple times with deionized water and methanol until neutral, and then vacuum dried to obtain the primary carbon material. Step 3: Transfer the corundum boat containing the primary carbon material obtained in Step 2 to a tube furnace, use nitrogen as a protective gas, and carry out high-temperature pyrolysis at a controllable temperature. Then, allow it to cool naturally to room temperature to obtain biocarbon catalytic material. The biocarbon catalytic material forms cone-shaped quinone and phenol active units with hydrogen cycling performance. Step 4: Add nitrobenzene compounds, nitrogen heterocyclic compounds, and a certain amount of water as solvent to a pressure reaction tube, and then add an appropriate amount of biochar material prepared in step 3 as catalyst. Under nitrogen conditions, react at a certain temperature for 8–36 h to obtain aniline compounds and nitrogen-containing aromatic heterocyclic compounds.

2. The method for preparing aromatic amine compounds by hydrogen transfer according to claim 1, characterized in that: In step 1, the mass ratio of cellulose to dealkalized lignin is 0.5 to 8:

1.

3. The method for preparing aromatic amine compounds by hydrogen transfer according to claim 1, characterized in that: Before impurity removal, the straw powder and 5 wt% NaOH aqueous solution were mixed at a mass ratio of 1:20-50, and the stirring time was 0.2-1 h. The treated straw powder was then vacuum dried at 25-60℃ to obtain the corresponding carbon precursor material.

4. The method for preparing aromatic amine compounds by hydrogen transfer according to claim 1, characterized in that: In step 1, the discarded straw is one of wheat straw, corn straw, rice straw, and soybean straw.

5. The method for preparing aromatic amine compounds by hydrogen transfer according to claim 1, characterized in that: In step 2, the mass ratio of carbon precursor material to P2O5 in the hydrothermal reactor is 1:5 to 8, the vacuum drying temperature of the primary carbon material is 25 to 60°C, the reaction temperature in the hydrothermal reactor is 100 to 150°C, and the reaction time is 1 to 8 h.

6. The method for preparing aromatic amine compounds by hydrogen transfer according to claim 1, characterized in that: In step 3, the heating rate of the tubular furnace is 5-10℃ / min, the preset end temperature of the tubular furnace is controlled at 600-950℃, and after the controllable high-temperature pyrolysis end temperature in the tubular furnace reaches the preset temperature, it is maintained for 2-4 hours.

7. The method for preparing aromatic amine compounds by hydrogen transfer according to claim 1, characterized in that: In step 4, the molar ratio of nitrobenzene compounds to nitrogen heterocyclic compounds is 1:1.5-3, the amount of catalyst involved in the reaction is 50-100 mg / mmol of nitrobenzene compounds, the reaction temperature of the catalytic reaction system is 90-150℃, the solvent in the catalytic reaction is deionized water, and the catalytic reaction time is 8-36 h.

8. The method for preparing aromatic amine compounds by hydrogen transfer according to claim 1, characterized in that: The nitrogen heterocyclic compound is one of the following: tetrahydroquinoline compounds, tetrahydroisoquinoline compounds, tetrahydroquinoxaloline compounds, and indoline compounds.

9. The method for preparing aromatic amine compounds by hydrogen transfer according to claim 1, characterized in that: The catalytic reaction equation is: 。

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