A preparation process and application of a catalyst for selective hydrogenation of nitro to hydroxylamine

Abstract

The present invention belongs to the field of fine chemical catalytic hydrogenation, and in particular, relates to a preparation process and application of a catalyst for selective hydrogenation of nitro to hydroxylamine. The catalyst is composed of a modified carrier and an active component attached to the carrier, the active component including Pt and auxiliary metal ions, and the auxiliary metal ions are selected from at least one metal ion of Au, Ag, Pd, Ni, Fe, Cu, and Ir. The preparation process of the catalyst comprises: S1 preparing modified activated carbon; S2 preparing an active component solution; S3 preparing a catalyst precursor: dropping the active component solution into a solution in which the modified activated carbon is dispersed, stirring and adsorbing to complete the preparation; S4 preparing a catalyst. The catalyst prepared by the present invention can realize selective hydrogenation to hydroxylamine, and a green and safe catalytic technology to realize nitro semi-hydrogenation to hydroxylamine, with high reaction activity, high selectivity, good stability, and the catalyst can be recycled while maintaining activity, which is conducive to large-scale production and use.

Description

Technical Field

[0001] The invention belongs to the field of fine chemical catalytic hydrogenation, and particularly relates to a preparation process and application of a catalyst for preparing hydroxylamine by selective hydrogenation of nitro groups. Background Art

[0002] Hydroxylamine aromatics is an organic intermediate used to synthesize important fine chemical products such as pesticides and medicines, and has broad market application prospects. Hydroxylamine aromatics are generally synthesized using the corresponding nitroaromatic compounds as raw materials through stoichiometric reactions, electrochemical reduction or catalytic hydrogenation.

[0003] Stoichiometric reactions include metal reduction and alkali sulfide reduction. Using metal iron, tin and sodium sulfide as reducing agents, nitro groups are reduced through stoichiometric reactions. The process is simple, but the waste residues and wastewater produced cause serious environmental pollution and have been gradually banned. The electrochemical reduction method has mild operating conditions and controllable products, but the current utilization rate is not high and the equipment requirements are extremely high, which makes industrialization difficult. Catalytic hydrogenation has become the mainstream process for nitro reduction in industry due to its cleanliness and high economic benefits.

[0004] The method of preparing hydroxylamine aromatics by catalytic hydrogenation of nitroaromatics may further hydrogenate the target product hydroxylamine aromatics into more stable amino aromatics. Therefore, in this type of catalytic hydrogenation reaction, a noble metal catalyst such as Pt or Pd with high activity is usually used to obtain high selectivity and high recovery rate for hydroxylamine aromatics. The previous technologies reported so far all add appropriate poisoning agents, such as DMSO, sulfur-containing compounds or organophosphorus, to the entire reaction system to partially poison the noble metals, so that the activity of the noble metal catalyst is reduced to the required level, thereby achieving the preparation of hydroxylamine aromatics.

[0005] For example, U.S. Pat. No. 3,694,509 discloses a method for adding DMSO to a reaction system using Pt / C as a catalyst to improve the selectivity for N-phenylhydroxylamine, which can achieve a recovery rate of 86%. U.S. Pat. No. 3,927,101 discloses a method for adding secondary or tertiary alkyl or cycloalkyl monoamines, piperidine, pyridine, alkyl pyridine, quinoline, isoquinoline or N, C alkyl derivatives to the reaction system, which can achieve a hydroxylamine recovery rate of 58.6%. U.S. Pat. No. 5,166,435 discloses a method for introducing N, P compounds, such as phosphoric acid, dimethylaminopyridine, triethyl phosphite, etc., to the reaction system, which can achieve a hydroxylamine recovery rate of up to 87%. In the document "Selective synthesis of N-aryl hydroxylamines by the hydrogenation of nitroaromatics using supported platinum catalysts", Takenaka et al. used Pt / SiO2 as a catalyst, added DMSO as a poisoning agent to the entire reaction system, and added organic bases such as piperidine, triethylamine, pyridine, etc. as activators, so that the selectivity of N-phenylhydroxylamine reached 99% while the conversion rate of nitrobenzene was close to 100% (Selective synthesis of N-aryl hydroxylamines by the hydrogenation of nitroaromatics using supported platinum catalysts, 2009, Y. Takenaka, T. Kiyosu, J.-C. Choi, T. Sakakura and H. Yasuda. Green Chemistry, 11: 1385-1390).

[0006] However, although the above-mentioned prior art method of adding a poisoning agent to the entire reaction system to reduce the activity of the catalyst can achieve high selectivity for hydroxylamine aromatics, the partially poisoned catalyst usually has a phenomenon of decreased activity or even complete deactivation after one operation cycle, thereby making the catalyst unable to be reused. In addition, the poisoning agent added to the reaction system may be miscible with the product hydroxylamine aromatics, making subsequent treatment difficult.

[0007] In 2016, Chen et al. published a method for synthesizing ethylenediamine-chelated Pt nanowires by adding ethylenediamine to a platinum precursor solution, which has a selectivity of up to 100% for hydrogenating nitrobenzene to produce phenylhydroxylamine (Interfacial electronic effects control the reaction, 2016, G. Chen, C. Xu, X. Huang, J. Ye, L. Gu, G. Li, Z. Tang, B. Wu, H. Yang, Z. Zhao, Z. Zhou, G. Fu, and N. Zheng, Nature Materials, 15: 564-569). Those skilled in the art should know that organic amines can cause poisoning of Pt nanocatalysts and inhibit activity, so they will not directly post-modify Pt nanocatalysts. The precious metal precursor platinum acetylacetonate used is not easy to obtain, the preparation process is complicated, and toxic gases and solvents such as CO and DMF are used, so it is difficult to prepare in batches, which is not conducive to industrial large-scale production.

[0008] Patent CN 117945946A discloses a method for synthesizing o-chlorophenylhydroxylamine by catalytic hydrogenation, wherein o-chloronitrobenzene is used as a raw material and Raney nickel is used as a catalyst, and o-chlorophenylhydroxylamine is synthesized at a hydrogen pressure of 1 MPa and a reaction temperature of 30-35°C. The method has a high yield of hydroxylamine, but the Raney nickel used has defects such as being dangerous and flammable, and is difficult to promote industrially.

[0009] From the above, it can be seen that the industry still needs a safe catalyst suitable for the hydrogenation reaction of nitroaromatic compounds, which has high selectivity for hydroxylamine aromatics, can be continuously applied to maintain activity, does not affect subsequent product processing, and can be produced on a large scale. Summary of the invention

[0010] In order to solve the problems existing in the prior art, the purpose of the present invention is to provide a preparation process and application of a catalyst for selective hydrogenation of nitro to hydroxylamine, the prepared catalyst can realize selective hydrogenation to hydroxylamine, and a green and safe catalytic technology to realize semi-hydrogenation of nitro to hydroxylamine, with high reaction activity, high selectivity, good stability, and the catalyst can be recycled while maintaining activity, which is conducive to large-scale production and use

[0011] In one aspect, the present invention provides a catalyst comprising a modified carrier and an active component attached to the carrier, wherein the active component comprises Pt and a promoter metal ion.

[0012] Furthermore, the auxiliary metal ions are selected from at least one metal ion of Au, Ag, Pd, Ni, Fe, Cu, and Ir.

[0013] Furthermore, the molar ratio of Pt to auxiliary metal ions is 1-10:1, preferably 2-7:1.

[0014] Furthermore, the carrier is one of carbon materials such as activated carbon, carbon nanotubes, graphene, and Ketjen black.

[0015] Furthermore, the average particle size of the activated carbon is 20 μm-60 μm, and the specific surface area of ​​the activated carbon is 700 m 2 / g-2000m 2 / g.

[0016] Furthermore, based on the weight of the catalyst, the loading amount of Pt is 0.01%-10%, the loading amount of the auxiliary metal ion is 0-10%, and the loading amount of at least one auxiliary metal ion is not zero.

[0017] Furthermore, based on the weight of the catalyst, the loading amount of Pt is 0.01%-10%, preferably 0.5%-8%, and the loading amount of Fe ions is 0.0001%-10%, preferably 0.1%-3%.

[0018] In one aspect, the present invention provides a process for preparing a catalyst, comprising the following steps:

[0019] S1 Preparation of modified activated carbon: The activated carbon is prepared by soaking and adsorbing organic amines, then drying and sintering;

[0020] S2: preparing an active component solution: dispersing a platinum-containing precursor, and then dropping a precursor solution of an auxiliary metal ion to obtain a solution;

[0021] S3: preparing a catalyst precursor: adding the active component solution dropwise into a solution in which modified activated carbon is dispersed, and stirring and adsorbing to complete the preparation;

[0022] S4 preparation of catalyst: the catalyst precursor is prepared after reduction and cleaning.

[0023] Further, the organic amine includes at least one of triethylamine, aniline, methylamine and melamine. Further, the soaking condition in S1 is 50-200°C, and stirring at 50-500 rpm for 1-6 hours. Further, after the activated carbon in S1 is soaked and adsorbed with organic amine, excess organic amine is removed by filtration, and then placed in an oven for drying, and after drying, placed in a muffle furnace for sintering. Further, the drying temperature in S1 is 60-110°C, and the drying time is 12-24h. Further, the sintering temperature in S1 is 300-450°C, and the sintering time is 3-8h.

[0024] Further, the platinum-containing precursor is selected from one or more of sodium chloroplatinate, chloroplatinic acid or dipotassium oxalateplatin. Further, the platinum-containing precursor is dispersed in a solvent, and the solvent is one or more of methanol, ethanol, tetrahydrofuran, and ultrapure water; the concentration of the platinum-containing precursor solution is 0.01-0.1g / mL. Further, the precursor solution of the auxiliary metal ion refers to an aqueous solution of a soluble salt of the corresponding auxiliary metal ion, such as at least one of the corresponding hydrochloride and nitrate, such as ferric chloride solution, copper nitrate solution, etc.; the concentration of the precursor solution of the auxiliary metal ion is 0.01-0.1g / mL. Further, the auxiliary metal ion is selected from at least one metal ion of Au, Ag, Pd, Ni, Fe, Cu, and Ir. Further, the mixing time for preparing the active component solution in S2 is 1-3 hours.

[0025] Furthermore, in S3, the stirring adsorption time is 1-12 hours.

[0026] Further, the reducing agent used in S4 is one of sodium formate, formaldehyde, formic acid, hypophosphite, hydrazine hydrate, ethylene glycol, sodium borohydride or hydrogen. Further, the conditions of the reduction reaction in S4 are: temperature 35-100°C, time 1-10h, when the reducing agent is sodium formate, formaldehyde, formic acid, hypophosphite, ethylene glycol, sodium borohydride or hydrazine hydrate, the amount of the reducing agent is 1-10 times the theoretical amount of substance required for the soluble salt of the active component metal and the soluble salt of the auxiliary metal to be reduced to the metal element, when the reducing agent is hydrogen, the hydrogen is introduced below the liquid surface of the solution, the hydrogen flow rate is 10-100mL / min, and the pressure of the hydrogen is normal pressure.

[0027] Furthermore, the solvent used in the cleaning and filtration process in S4 is one or more of methanol, ethanol, tetrahydrofuran, and ultrapure water.

[0028] In another aspect, the present invention provides a process for hydrogenating nitro compounds using the catalyst of the present invention, wherein the nitro compounds are converted into hydroxylamine compounds.

[0029] Furthermore, the process is as follows: in a hydrogen atmosphere, a nitro compound and a catalyst are mixed and stirred to react to obtain a hydroxylamine compound.

[0030] Furthermore, the nitro compounds include nitrobenzene, p-fluoronitrobenzene, N-[2-[[1-(4-chlorophenyl)pyrazol-3-yl]oxymethyl]phenyl]-nitrobenzene, o-methylnitrobenzene, and the like.

[0031] Furthermore, the mass ratio of the nitro compound to the catalyst is 50-1000:1.

[0032] Furthermore, the reaction is carried out in an organic solvent, and the organic solvent is selected from methanol, ethanol, tetrahydrofuran, water, dichloroethane, tetrachloroethylene or toluene.

[0033] Furthermore, an amine auxiliary agent needs to be added during the reaction, and the amine auxiliary agent is selected from at least one of triethylamine, aniline, ethylenediamine, and methylamine. Furthermore, the mass ratio of the catalyst to the amine auxiliary agent is 100-5000:1.

[0034] Furthermore, during the reaction process, the temperature is 0-60°C and the hydrogen pressure is 0.1-2MPa.

[0035] Beneficial Effects

[0036] The catalyst prepared by the present invention can effectively catalyze the conversion of nitro compounds into hydroxylamine compounds, can control the realization of nitro semi-hydrogenation, can maintain the activity of the catalyst, and can be reused. The catalyst is applied to the selective hydrogenation of nitrobenzene containing functional groups such as nitrobenzene, pyrazole ether intermediates, and p-fluoronitrobenzene to prepare functional group-containing nitrohydroxylamine, the raw material conversion rate is greater than 99.9%, and the selectivity of the target product hydroxylamine is greater than 99.8%.

[0037] In the catalyst preparation process of the present invention, the organic amine adsorbed in the activated carbon is used as a base and a nitrogen source, and after sintering, the activated carbon is modified by the N element, which can inhibit the agglomeration of metal ions and improve the dispersion of metal ions. The metal ion source (Pt and auxiliary metal ions) with a soluble salt as an active ingredient is dispersed in water, which reduces the agglomeration of metal ions and can be uniformly attached to the inside and outside of the pores of the modified activated carbon. The particle distribution and size are easier to control, preventing agglomeration, which is beneficial to inhibiting catalytic activity, and can also ensure that the catalyst has a catalytic activity of effectively catalyzing the conversion of nitro groups to hydroxylamine groups, and has high selectivity.

[0038] The catalyst prepared by the present invention is applied to the process of hydrogenation of nitro compounds, has high reaction activity, high selectivity and good stability, and realizes high selectivity of noble metal catalysts in preparing hydroxylamine by nitro hydrogenation.

[0039] The technical solution of the present invention is further described in detail below in conjunction with embodiments. DETAILED DESCRIPTION

[0040] The present invention is further described below in conjunction with specific examples. These examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. The reagents used in the present invention can all be commercially available.

[0041] Catalyst Preparation Example 1

[0042] The activated carbon was immersed in a 0.1 mol / L triethylamine solution at 50°C and stirred at 200 rpm for 2 hours. The activated carbon after immersion was filtered and dried in an oven at 60°C for 12 hours. After drying, the activated carbon was sintered in a muffle furnace at 450°C for 3 hours to obtain modified activated carbon.

[0043] Chloroplatinic acid containing 3% platinum based on the weight of the catalyst is dispersed in ultrapure water to obtain a 0.1 g / mL chloroplatinic acid solution, and a 0.1 g / mL FeCl3 solution containing 1% iron based on the weight of the catalyst is added dropwise to the chloroplatinic acid solution, and the mixture is mixed for 3 hours to obtain a mixed solution of a precursor; the mixed solution of the precursor is slowly added dropwise to a solution in which modified activated carbon is dispersed and stirred for 12 hours, and the mixed precursor adsorbed on the modified activated carbon is reduced with sodium formate at 100°C for 3 hours; the reduced catalyst is filtered and washed with ultrapure water to obtain a platinum-carbon catalyst for selective hydrogenation of nitro to produce hydroxylamine.

[0044] Preparation Example 2 of Catalyst

[0045] The activated carbon was immersed in a 0.1 mol / L methylamine solution at 100°C and stirred at 400 rpm for 1 hour. The activated carbon after immersion was filtered and dried in an oven at 100°C for 20 hours. After drying, the activated carbon was sintered in a muffle furnace at 300°C for 8 hours to obtain modified activated carbon.

[0046] Dipotassium oxalate containing 10% platinum based on the weight of the catalyst is dispersed in ultrapure water to obtain a 0.1 g / mL chloroplatinic acid solution, and a 0.05 g / mL FeCl3 solution containing 3% iron based on the weight of the catalyst is added dropwise to the chloroplatinic acid solution, and the mixture is mixed for 1 hour to obtain a mixed solution of the precursor; the mixed solution of the precursor is slowly added dropwise to a solution in which modified activated carbon is dispersed and stirred for 8 hours, and the mixed precursor adsorbed on the modified activated carbon is reduced with hydrazine hydrate at 50°C for 8 hours; the reduced catalyst is filtered and washed with ultrapure water to obtain a platinum-carbon catalyst for selective hydrogenation of nitro to produce hydroxylamine.

[0047] Catalyst Preparation Example 3

[0048] The difference from the catalyst preparation example 1 is that the auxiliary metal ion is Cu.

[0049] Application Example 1

[0050] 100 g of p-fluoronitrobenzene and 1000 g of methanol were added to an autoclave, and the platinum-carbon catalyst prepared in Catalyst Preparation Example 2 was added; the amount of the catalyst was 0.6 wt % of the raw material, and the auxiliary methylamine was added, the mass ratio of the catalyst to the auxiliary was 500:1, the catalytic temperature was 10-20 ° C, and hydrogen was introduced at a pressure of 1.0 MPa. The catalytic reaction was carried out for 3.0 h to obtain a hydrogenated solution; the raw material conversion rate was 99.98%, and the selectivity of the target product p-fluorohydroxylamine benzene was 99.96%.

[0051] Application Example 2:

[0052] 100 g of p-fluoronitrobenzene and 1000 g of methanol were added to an autoclave, and the platinum-carbon catalyst prepared in Catalyst Preparation Example 1 was added; the amount of the catalyst was 0.6 wt % of the raw material, and the auxiliary agent triethylamine was added, the mass ratio of the catalyst to the auxiliary agent was 100:1, the catalytic temperature was 10-20 ° C, and hydrogen gas at a pressure of 1.0 MPa was introduced. The catalytic reaction was carried out for 3.0 h to obtain a hydrogenated solution; the raw material conversion rate was 99.95%, and the selectivity of the target product p-fluorohydroxylamine benzene was 99.91%.

[0053] Application Example 3:

[0054] 100 g of nitrobenzene and 1000 g of anhydrous ethanol were added to an autoclave, and the platinum-carbon catalyst prepared in Catalyst Preparation Example 1 was added; the amount of the catalyst was 0.6 wt % of the raw material, and the auxiliary methylamine was added, the mass ratio of the catalyst to the auxiliary was 200:1, the catalytic temperature was 20-25 ° C, and hydrogen gas at a pressure of 1.0 MPa was introduced. The catalytic reaction was carried out for 1.0 h to obtain a hydrogenated solution; the raw material conversion rate was 99.96%, and the selectivity of the target product hydroxylamine benzene was 99.88%.

[0055] Application Example 4:

[0056] 100 g of o-methylnitrobenzene and 1000 g of tetrahydrofuran were added to an autoclave, and the platinum-carbon catalyst prepared in Example 1 was added; the amount of the catalyst was 0.6 wt % of the raw material, and the auxiliary methylamine was added, the mass ratio of the catalyst to the auxiliary was 500:1, the catalytic temperature was 25-40 ° C, and hydrogen gas at a pressure of 1.0 MPa was introduced. The catalytic reaction was carried out for 1.5 hours to obtain an o-methylphenylhydroxylamine solution; the raw material conversion rate was 99.91%, and the selectivity of the target product o-methylhydroxylamine benzene was 99.40%.

[0057] Application Example 5:

[0058] 100 g of N-[2-[[1-(4-chlorophenyl)pyrazol-3-yl]oxymethyl]phenyl]-nitrobenzene and 1000 g of tetrahydrofuran were added to an autoclave, and the platinum-carbon catalyst prepared in Example 1 was added as a catalyst; the amount of the catalyst was 0.4 wt % of the raw material, and an auxiliary agent, triethylamine, was added, the mass ratio of the catalyst to the auxiliary agent was 500:1, the catalytic temperature was 20-25 ° C, and hydrogen gas at a pressure of 1.0 MPa was introduced. The catalytic reaction was carried out for 2.5 h to obtain N-[2-[[1-(4-chlorophenyl)pyrazol-3-yl]oxymethyl]phenyl]-hydroxylamine solution; the raw material conversion rate was 99.93%, and the selectivity of the target product hydroxylamine was 99.84%.

[0059] Application Example 6:

[0060] 100g of nitrobenzene and 1000g of anhydrous ethanol were added to the autoclave, and the platinum-carbon catalyst prepared in Example 1 was added to the catalyst; the amount of the catalyst was 0.6wt% of the first kettle raw material, and the auxiliary aniline was added, the mass ratio of the catalyst to the auxiliary was 500:1, and 0.06wt% was added, and 500:1 of the auxiliary aniline was added. The catalytic temperature was 20-25°C, and hydrogen gas at a pressure of 1.5MPa was introduced. The catalytic reaction was carried out for 2.0-3.0h to obtain a hydrogenated solution; the catalyst was applied 10 times, the raw material conversion rate was greater than 99.90%, and the selectivity of the target product hydroxylamine benzene was greater than 99.80%; the recovery and application conditions are shown in Table 1:

[0061]

[0062] Application Example 7:

[0063] Take 100g N-[2-[[1-(4-chlorophenyl)pyrazol-3-yl]oxymethyl]phenyl]-nitrobenzene and 1000g tetrahydrofuran and add them into an autoclave, and add the platinum-carbon catalyst prepared in Catalyst Preparation Example 1; the amount of the catalyst is 0.4wt% of the first kettle raw material, and the auxiliary agent triethylamine is added, the mass ratio of the catalyst to the auxiliary agent is 500:1, and 0.04wt% is added, and 500:1 of the auxiliary agent triethylamine is added. The catalyst was added with 0.06wt%, the catalytic temperature was 20-25°C, hydrogen was introduced at a pressure of 1.5MPa, and the catalytic reaction was carried out for 2.5-3.5h to obtain N-[2-[[1-(4-chlorophenyl)pyrazol-3-yl]oxymethyl]phenyl]-hydroxylamine solution; the number of applications was 20 times, the raw material conversion rate was greater than 99.90%, and the selectivity of the target product N-[2-[[1-(4-chlorophenyl)pyrazol-3-yl]oxymethyl]phenyl]-phenylhydroxylamine was greater than 99.80%; the recovery and application conditions are shown in Table 2:

[0064]

[0065] Application Examples 1-7 of the present application show that the platinum-carbon catalyst prepared by the present invention has good catalytic activity in the process of converting nitro compounds into hydroxylamine compounds, and the conversion rate is almost above 99.9% and the selectivity is above 99%.

[0066] Application Examples 6-7 of the present application show that the platinum-carbon catalyst prepared by the present invention has high selectivity and high activity, can be repeatedly used, has strong anti-toxicity and stability, and can be repeatedly used 20 times. The selectivity of the catalytic reaction is also maintained at more than 99%, and has a high utilization value.

[0067] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A catalyst, characterized in that The catalyst is composed of a modified carrier and an active component attached to the carrier, wherein the active component includes Pt and an auxiliary metal ion; The modified carrier is prepared by soaking activated carbon to adsorb organic amine, followed by drying and sintering; The auxiliary metal ion is selected from at least one metal ion of Au, Ag, Pd, Ni, Fe, Cu, and Ir; The molar ratio of Pt to auxiliary metal ions is 1-10:

1.

2. The catalyst according to claim 1, characterized in that The molar ratio of Pt to auxiliary metal ions is 2-7:

1.

3. The catalyst according to claim 1, characterized in that The average particle size of the activated carbon is 20 μm-60 μm, and the specific surface area of ​​the activated carbon is 700 m 2 / g-2000m 2 / g; based on the weight of the catalyst, the Pt loading is 0.01%-10%, the auxiliary metal ion loading is 0-10%, and the loading of at least one auxiliary metal ion is not 0.

4. The catalyst according to claim 1, characterized in that Based on the weight of the catalyst, the loading amount of Pt is 0.01%-10%, and the loading amount of Fe ions is 0.0001%-10%.

5. The catalyst according to claim 4, characterized in that Based on the weight of the catalyst, the loading amount of Pt is 0.5%-8%, and the loading amount of Fe ions is 0.1%-3%.

6. A process for preparing the catalyst according to claim 1, characterized in that: The following steps are involved: S1 Preparation of modified activated carbon: The activated carbon is prepared by soaking and adsorbing organic amines, then drying and sintering; S2: preparing an active component solution: dispersing a platinum-containing precursor, and then dropping a precursor solution of an auxiliary metal ion to obtain a solution; S3: preparing a catalyst precursor: adding the active component solution dropwise into a solution in which modified activated carbon is dispersed, and stirring and adsorbing to complete the preparation; S4 preparation of catalyst: the catalyst precursor is prepared after reduction and cleaning.

7. The preparation process according to claim 6, characterized in that: The organic amine comprises at least one of triethylamine, aniline, methylamine and melamine; the soaking condition in S1 is 50-200°C, and the stirring is performed at 50-500 rpm for 1-6 hours; the activated carbon in S1 absorbs the organic amine after soaking, and then the excess organic amine is removed by filtration, and then placed in an oven for drying, and after drying, placed in a muffle furnace for sintering.

8. The preparation process according to claim 7, characterized in that: In S1, the drying temperature is 60-110°C, and the drying time is 12-24h; the sintering temperature is 300-450°C, and the sintering time is 3-8h.

9. The preparation process according to claim 6, characterized in that: The platinum-containing precursor in S2 is selected from one or more of sodium chloroplatinate, chloroplatinic acid or dipotassium oxalateplatin; the platinum-containing precursor is dispersed in a solvent, and the solvent is one or more of methanol, ethanol, tetrahydrofuran, and ultrapure water; the concentration of the platinum-containing precursor solution is 0.01-0.1 g / mL.

10. The preparation process according to claim 6, characterized in that: The precursor solution of the co-metal ion refers to an aqueous solution of a soluble salt of the corresponding co-metal ion.

11. The preparation process according to claim 10, characterized in that: The precursor solution of the auxiliary metal ion is a ferric chloride solution or a copper nitrate solution; the concentration is 0.01-0.1 g / mL.

12. The preparation process according to claim 6, characterized in that: The mixing time for preparing the active component solution in S2 is 1-3 hours.

13. The preparation process according to claim 6, characterized in that: The stirring adsorption time in S3 is 1-12 hours.

14. The preparation process according to claim 6, characterized in that: The reducing agent used in S4 is one of sodium formate, formaldehyde, formic acid, hypophosphite, hydrazine hydrate, ethylene glycol, sodium borohydride or hydrogen.

15. The preparation process according to claim 6, characterized in that: The conditions for the reduction reaction in S4 are: temperature 35-100°C, time 1-10h.

16. The preparation process according to claim 6, characterized in that: The solvent used in the cleaning and filtration process in S4 is one or more of methanol, ethanol, tetrahydrofuran, and ultrapure water.

17. A process for hydrogenating nitro compounds using the catalyst according to claim 1, characterized in that: Convert nitro compounds into hydroxylamine compounds.

18. The process for hydrogenating nitro compounds according to claim 17, characterized in that: The process is as follows: in a hydrogen atmosphere, nitro compounds and catalysts are mixed and stirred to react to obtain hydroxylamine compounds.

19. The process for hydrogenating nitro compounds according to claim 18, characterized in that: During the reaction, an amine auxiliary agent needs to be added, and the amine auxiliary agent is selected from at least one of triethylamine, aniline, ethylenediamine and methylamine.

20. The process for hydrogenating nitro compounds according to any one of claims 17 to 19, characterized in that: The nitro compounds include nitrobenzene, p-fluoronitrobenzene, N-[2-[[1-(4-chlorophenyl)pyrazol-3-yl]oxymethyl]phenyl]-nitrobenzene or o-methylnitrobenzene.

21. The process for hydrogenating nitro compounds according to claim 20, characterized in that: The mass ratio of the nitro compound to the catalyst is 50-1000:

1.

22. The process for hydrogenating nitro compounds according to any one of claims 17 to 19, characterized in that: The reaction is carried out in an organic solvent selected from methanol, ethanol, tetrahydrofuran, dichloroethane, tetrachloroethylene or toluene.

23. The process for hydrogenating nitro compounds according to any one of claims 17 to 19, characterized in that: During the reaction, the temperature is 0-60°C and the hydrogen pressure is 0.1-2MPa.

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