Catalyst for preparing phenyl hydroxylamine compound and process method

Abstract

The invention discloses a catalyst for preparing phenyl hydroxylamine compounds and a process method, the catalyst comprises a carrier and an active noble metal loaded on the carrier, the active noble metal is platinum, the mass percentage of the active noble metal in the catalyst is 0.5%-1%, and the raw material of the carrier is coconut shell columnar activated carbon. The preparation method of the catalyst comprises the following steps: treating coconut shell columnar activated carbon with hydrogen peroxide, stirring and dipping the treated coconut shell columnar activated carbon and an active noble metal soluble salt solution, and then carrying out reduction, assistant regulation and control, temperature programmed drying and hydrogen reduction to obtain the catalyst for preparing the phenylhydroxylamine compound. The catalyst can realize selective controllable hydrogenation of nitrobenzene compounds to prepare phenylhydroxylamine, the conversion rate exceeds 90%, the selectivity is high, and the catalyst has the characteristics of high reaction selectivity and conversion rate.

Description

Technical Field

[0001] The invention belongs to the technical field of catalytic preparation, and specifically relates to a catalyst and a process method for preparing phenylhydroxylamine compounds. Background Art

[0002] Phenylhydroxylamine compounds are a very important class of chemical, pesticide and pharmaceutical intermediates. Currently, they are mainly obtained by hydrogenating nitrobenzene compounds, and most of them use Raney-Ni or Rh / C as catalysts and hydrazine hydrate as a reducing agent (Yang Ying, Zhang Yang, et al. Central South Pharmacy, 2015, 13, 565; He Dian, Ma Shangxian, et al. Chinese Journal of New Drugs, 2014, 23, 1438; CN103588599A; PCT 2012120029; CN117945946A; CN106187810A; CN105646276A). There is also a zinc powder reduction method, such as: Salman, H. Het al. Trop. J. Pharm. Res., 2020, 19, 342; Liang, F.-S. et al. ACS Synth. Biol. 2017, 6, 921; Jiang, J.-Y. et al. Green Chem., 2009, 11, 1397. There are few reports on palladium carbon and platinum carbon as catalysts (Dash, P. et al. Green Chem., 2013, 15, 3421.).

[0003] In summary, the above methods mainly face the following problems: 1. The types of catalysts are limited, and nickel-based catalysts are mainly used, which have a high risk factor in industrial production; 2. The reducing agent is mostly hydrazine hydrate, which has poor atom economy; 3. The reaction efficiency is not high and the applicability of the substrate is limited. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a catalyst and a process for preparing phenylhydroxylamine compounds in view of the above-mentioned deficiencies in the prior art. The catalyst comprises a carrier of treated coconut shell columnar activated carbon and precious metal platinum, and can realize the selective catalytic hydrogenation of nitrobenzene compounds to obtain phenylhydroxylamine compounds, and has the characteristics of high reaction selectivity and conversion rate.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a catalyst for preparing phenylhydroxylamine compounds, characterized in that it includes a carrier and an active precious metal loaded on the carrier, the active precious metal is platinum, the mass percentage of the active precious metal in the catalyst is 0.5% to 1%, and the raw material of the carrier is coconut shell columnar activated carbon.

[0006] The above-mentioned catalyst for preparing phenylhydroxylamine compounds is characterized in that the coconut shell columnar activated carbon has a diameter of 1.5 mm to 2.2 mm, a length of 2 mm to 4 mm, and a specific surface area of ​​1000 m 2 / g~1200m 2 / g, pore volume is 0.85cm 3 / g~0.95cm 3 / g.

[0007] Furthermore, the present invention provides a method for preparing the catalyst for preparing the above-mentioned phenylhydroxylamine compounds, characterized in that it comprises the following steps:

[0008] Step 1: Immerse coconut shell columnar activated carbon in a hydrogen peroxide solution at a temperature of 50°C to 60°C for 4 to 5 hours, wash with water until the pH is greater than 5, and dry to a constant weight to obtain a carrier;

[0009] Step 2: dissolving a soluble salt of an active noble metal in dilute nitric acid to obtain a solution A, adding the support in step 1 to the solution A, and impregnating the solution under stirring at room temperature for 20 h to 24 h to obtain an impregnated system;

[0010] Step 3: at 0°C to 5°C, add the solution of the alkali metal reducing agent and the auxiliary agent dropwise to the impregnated system of step 2, let stand at 0°C to 5°C for 2h to 3h, wash with water, vacuum dry at 60°C to 70°C for 3h to 5h, heat to 110°C to 120°C, continue vacuum drying to constant weight, and cool naturally to obtain a catalyst precursor;

[0011] Step 4: subjecting the catalyst precursor in step 3 to hydrogen reduction to obtain a catalyst for preparing phenylhydroxylamine compounds.

[0012] The above method is characterized in that the drying temperature in step one is 100°C to 120°C; the mass concentration of dilute nitric acid in step two is 0.5% to 1%, the mass of the dilute nitric acid is 2 to 4 times the total mass of the soluble salt of the active precious metal and the carrier, and the soluble salt of the active precious metal is a nitrate of the active precious metal or a chloride of the active precious metal.

[0013] The above method is characterized in that the alkali metal-containing reducing agent in step three is sodium borohydride or sodium formate, the auxiliary agent is a sulfur-containing compound or a nitrogen-containing compound, the molar ratio of the alkali metal-containing reducing agent to the active precious metal is (4-5):1, the molar ratio of the auxiliary agent to the active precious metal is (0.01-0.1):1, and the mass percentage of the alkali metal-containing reducing agent in the solution of the alkali metal-containing reducing agent and the auxiliary agent is 1% to 3%; in step three, washing with water until the system pH is 8-10.

[0014] The above method is characterized in that the sulfur-containing compound includes sodium sulfide, sodium sulfite or thiourea, and the nitrogen-containing compound includes triethylamine, ethylenediaminetetraacetic acid (EDTA) or N,N,N',N'-tetramethylethylenediamine (TMEDA).

[0015] The above method is characterized in that the hydrogen reduction in step 4 includes: in the presence of hydrogen, heating the catalyst precursor to 300°C to 350°C at a heating rate of 2°C / min to 3°C / min, maintaining for 2h to 4h, and cooling naturally.

[0016] Furthermore, the present invention provides a process for preparing phenylhydroxylamine compounds by using the above catalyst, characterized in that the reactor used in the process is a fixed bed tubular reactor, and the process method comprises: mixing nitrobenzene compounds with a solvent, introducing a mixed gas of hydrogen and nitrogen, and performing a catalytic reaction under the action of the catalyst; the reaction pressure is 0.5MPa to 0.8MPa, the temperature is 5°C to 20°C, and the reaction space velocity is 0.3g / g·h -1 ~0.5g / g·h -1 .

[0017] The above-mentioned process method is characterized in that the volume percentage of hydrogen in the mixed gas of hydrogen and nitrogen is 10% to 30%; the reaction solvent is one or more of tetrahydrofuran, dioxane, ethanol and 1,2-dichloroethane, and the mass ratio of the reaction solvent to the nitrobenzene compound is (10 to 20):1.

[0018] The above-mentioned process method is characterized in that the nitrobenzene compound is nitrobenzene or substituted nitrobenzene, and the substituent of the substituted nitrobenzene can be a single or multiple substituents at the ortho, meta, or para position of nitrobenzene, and the substituent can be an alkyl, aryl, halogen or heteroatom substituent, etc.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] 1. The present invention provides a catalyst for preparing phenylhydroxylamine compounds. The catalyst comprises a carrier of treated coconut shell columnar activated carbon and precious metal platinum, and is assisted by auxiliary agents for regulation. It can realize the selective catalytic hydrogenation of nitrobenzene compounds to prepare phenylhydroxylamine compounds, and has the characteristics of high reaction selectivity and conversion rate.

[0021] 2. The production process of phenylhydroxylamine compounds of the present invention can remove the reaction products in time, effectively avoid the occurrence of side reactions such as excessive hydrogenation, and ensure that the continuous reaction is carried out smoothly and safely.

[0022] 3. The production process of phenylhydroxylamine compounds of the present invention can realize the continuous production of phenylhydroxylamine compounds, and has the characteristics of high long-term operation stability, low energy consumption and cost.

[0023] 4. Preferably, the production process of phenylhydroxylamine compounds of the present invention uses nitrobenzene compounds and solvents as main raw materials, and under the action of the above-mentioned catalyst, can effectively realize the continuous production of phenylhydroxylamine compounds from nitrobenzene compounds.

[0024] 5. Preferably, the present invention provides a method for continuous production of phenylhydroxylamine compounds. Based on the above catalyst and process method, the occurrence of side reactions such as further hydrogenation of phenylhydroxylamine to obtain aniline compounds or disproportionation reaction of phenylhydroxylamine to obtain aniline and nitrosobenzene can be effectively avoided. The conversion rate exceeds 90%, and can reach up to 100%, and the selectivity is high, reaching more than 90%.

[0025] The technical solution of the present invention is further described in detail below in conjunction with embodiments. DETAILED DESCRIPTION

[0026] The present invention is further described below in conjunction with specific embodiments, so as to more clearly explain the advantages of the present invention. The embodiments described are only exemplary and do not constitute any limitation to the scope of the present invention.

[0027] Example 1

[0028] The present embodiment provides a catalyst for preparing phenylhydroxylamine compounds, the catalyst comprising a carrier and an active noble metal loaded on the carrier, the active noble metal being platinum, the mass percentage of platinum in the catalyst being 0.5%, the carrier raw material being coconut shell columnar activated carbon, the coconut shell columnar activated carbon having a diameter of 1.5 mm to 2.2 mm, a length of 2 mm to 4 mm, and a specific surface area of ​​1000 m 2 / g~1200m 2 / g, pore volume is 0.85cm 3 / g~0.95cm 3 / g.

[0029] This embodiment also provides a method for preparing a catalyst for preparing phenylhydroxylamine compounds, comprising the following steps:

[0030] Step 1, immersing the coconut shell columnar activated carbon in a 5wt% hydrogen peroxide solution at 50°C for 4 hours, washing with water until the pH value is greater than 5, and drying at 100°C to constant weight to obtain a carrier;

[0031] Step 2: according to the mass percentage of platinum in the preset catalyst, dissolve the platinum soluble salt in dilute nitric acid with a mass percentage of 0.5wt% to obtain solution A, add the carrier described in step 1 to the solution A, and impregnate for 20 hours at room temperature with stirring to obtain an impregnated system; the platinum soluble salt is platinum nitrate; the room temperature is 20°C to 25°C; the mass of the dilute nitric acid is twice the total mass of the platinum nitrate and the carrier;

[0032] Step 3, at 0-5°C, add the solution of the alkali metal-containing reducing agent and the auxiliary agent dropwise to the impregnated system in step 2, let it stand at 0-5°C for 2h, wash with water until the pH of the system is 9, vacuum dry at 65°C for 3h, heat to 110°C and continue vacuum drying to constant weight, cool naturally to obtain a catalyst precursor; the alkali metal-containing reducing agent is sodium borohydride, and the molar ratio of the alkali metal-containing reducing agent to platinum is 4:1; the mass percentage of the alkali metal-containing reducing agent in the solution of the alkali metal-containing reducing agent and the auxiliary agent is 1%; the auxiliary agent is sodium sulfide, and the molar ratio of the auxiliary agent to platinum is 0.05:1; the water washing comprises: decanting the system after standing to remove the supernatant to obtain a solid phase, washing the solid phase by multiple immersions until the pH of the supernatant is 9, and completing the water washing;

[0033] The immersion washing comprises: immersing the solid phase in water, stirring it fully and then letting it stand, and removing the supernatant by decantation;

[0034] Step 4: Hydrogen reduction is performed on the catalyst precursor in step 3 to obtain a catalyst for preparing phenylhydroxylamine compounds; the hydrogen reduction comprises: in the presence of hydrogen, heating the catalyst precursor to 300° C. at a heating rate of 2° C. / min, maintaining for 3 hours, and naturally cooling; in the catalyst for preparing phenylhydroxylamine compounds, the mass percentage of platinum is 0.5%, recorded as S1.

[0035] Example 2

[0036] This example is the same as Example 1, except that the mass percentage of platinum is 0.8%, and the obtained catalyst is recorded as S2.

[0037] Example 3

[0038] This embodiment is the same as embodiment 1, except that the mass percentage of platinum is 1.0%, which is denoted as S3.

[0039] Example 4

[0040] This embodiment is the same as embodiment 1, except that the mass of the dilute nitric acid is 3 times the total mass of the platinum nitrate and the carrier, denoted as S4.

[0041] Example 5

[0042] This embodiment is the same as embodiment 1, except that the mass of the dilute nitric acid is 4 times the total mass of the platinum nitrate and the carrier, denoted as S5.

[0043] Example 6

[0044] This embodiment is the same as Embodiment 1, except that the mass percentage of the alkali metal-containing reducing agent in the solution containing the alkali metal reducing agent and the auxiliary agent is 2%, which is recorded as S6.

[0045] Example 7

[0046] This embodiment is the same as Embodiment 1, except that the mass percentage of the alkali metal-containing reducing agent in the solution containing the alkali metal reducing agent and the auxiliary agent is 3%, which is recorded as S7.

[0047] Example 8

[0048] The present embodiment provides a catalyst for preparing phenylhydroxylamine compounds, the catalyst comprising a carrier and an active noble metal loaded on the carrier, the active noble metal being platinum, the mass percentage of platinum in the catalyst being 0.5%, the carrier raw material being coconut shell columnar activated carbon, the coconut shell columnar activated carbon having a diameter of 1.5 mm to 2.2 mm, a length of 2 mm to 4 mm, and a specific surface area of ​​1000 m 2 / g~1200m 2 / g, pore volume is 0.85cm 3 / g~0.95cm 3 / g.

[0049] This embodiment also provides a method for preparing a catalyst for preparing phenylhydroxylamine compounds, comprising the following steps:

[0050] Step 1, immersing the coconut shell columnar activated carbon in a 5wt% hydrogen peroxide solution at 60°C for 5 hours, washing with water until the pH value is greater than 5, and drying at 120°C to constant weight to obtain a carrier;

[0051] Step 2: according to the mass percentage of platinum in the preset catalyst, a platinum soluble salt is dissolved in dilute nitric acid with a mass percentage of 1wt% to obtain solution A, and the carrier described in step 1 is added to the solution A, and the mixture is stirred and impregnated at room temperature for 24 hours to obtain an impregnated system; the platinum soluble salt is platinum chloride; the room temperature is 20°C to 25°C; the mass of the dilute nitric acid is 4 times the total mass of the platinum nitrate and the carrier;

[0052] Step 3, at 0-5°C, add the solution of the alkali metal-containing reducing agent and the auxiliary agent dropwise to the impregnated system in step 2, let it stand at 0-5°C for 3h, wash with water until the pH of the system is 8, vacuum dry at 70°C for 4h, heat to 120°C and continue vacuum drying to constant weight, cool naturally to obtain a catalyst precursor; the alkali metal-containing reducing agent is sodium borohydride, and the molar ratio of the alkali metal-containing reducing agent to platinum is 5:1; the mass percentage of the alkali metal-containing reducing agent in the solution of the alkali metal-containing reducing agent and the auxiliary agent is 1%; the auxiliary agent is sodium sulfide, and the molar ratio of the auxiliary agent to platinum is 0.01:1; the water washing comprises: decanting the system after standing to remove the supernatant to obtain a solid phase, washing the solid phase by multiple immersions until the pH of the supernatant is 8, and completing the water washing;

[0053] The immersion washing comprises: immersing the solid phase in water, stirring it fully and then letting it stand, and removing the supernatant by decantation;

[0054] Step 4: Hydrogen reduction is performed on the catalyst precursor in step 3 to obtain a catalyst for preparing phenylhydroxylamine compounds; the hydrogen reduction comprises: in a hydrogen state, heating the catalyst precursor to 350° C. at a heating rate of 3° C. / min, maintaining for 2 hours, and naturally cooling; in the catalyst for preparing phenylhydroxylamine compounds, the mass percentage of platinum is 0.5%, recorded as S8.

[0055] Example 9

[0056] This embodiment is the same as embodiment 8, except that the alkali metal-containing reducing agent is sodium formate, denoted as S9.

[0057] Example 10

[0058] This embodiment is the same as embodiment 8, except that the auxiliary agent is sodium sulfite, denoted as S10.

[0059] Embodiment 11

[0060] The present embodiment provides a catalyst for preparing phenylhydroxylamine compounds, the catalyst comprising a carrier and an active noble metal loaded on the carrier, the active noble metal being platinum, the mass percentage of platinum in the catalyst being 0.5%, the carrier raw material being coconut shell columnar activated carbon, the coconut shell columnar activated carbon having a diameter of 1.5 mm to 2.2 mm, a length of 2 mm to 4 mm, and a specific surface area of ​​1000 m 2 / g~1200m 2 / g, pore volume is 0.85cm 3 / g~0.95cm 3 / g.

[0061] This embodiment also provides a method for preparing a catalyst for preparing phenylhydroxylamine compounds, comprising the following steps:

[0062] Step 1, immersing the coconut shell columnar activated carbon in a 5wt% hydrogen peroxide solution at 55°C for 4.5h, washing with water until the pH value is greater than 5, and drying at 110°C to constant weight to obtain a carrier;

[0063] Step 2: According to the mass percentage of platinum in the preset catalyst, a platinum soluble salt is dissolved in dilute nitric acid with a mass percentage of 0.8wt% to obtain solution A, and the carrier described in step 1 is added to the solution A, and the mixture is stirred and impregnated at room temperature for 22 hours to obtain an impregnated system; the platinum soluble salt is platinum chloride; the room temperature is 20°C to 25°C; the mass of the dilute nitric acid is 3 times the total mass of the platinum nitrate and the carrier;

[0064] Step 3: at 0-5°C, add the solution of the alkali metal-containing reducing agent and the auxiliary agent dropwise to the impregnated system in step 2, stand at 0-5°C for 2.5 hours, wash with water until the pH value of the system is 10, vacuum dry at 60°C for 5 hours, heat to 115°C and continue vacuum drying to constant weight, cool naturally to obtain a catalyst precursor; the alkali metal-containing reducing agent is sodium borohydride, and the molar ratio of the alkali metal-containing reducing agent to platinum is 4.5:1; the mass percentage of the alkali metal-containing reducing agent in the solution of the alkali metal-containing reducing agent and the auxiliary agent is 1%; the auxiliary agent is thiourea, and the molar ratio of the auxiliary agent to platinum is 0.1:1; the washing comprises: decanting the system after standing to remove the supernatant to obtain a solid phase, washing the solid phase by multiple immersions until the pH value of the supernatant is 10, and completing the washing;

[0065] The immersion washing comprises: immersing the solid phase in water, stirring it fully and then letting it stand, and removing the supernatant by decantation;

[0066] Step 4: Hydrogen reduction is performed on the catalyst precursor in step 3 to obtain a catalyst for preparing phenylhydroxylamine compounds; the hydrogen reduction comprises: in a hydrogen state, heating the catalyst precursor to 320° C. at a heating rate of 2° C. / min, maintaining for 4 hours, and naturally cooling; in the catalyst for preparing phenylhydroxylamine compounds, the mass percentage of platinum is 0.5%, recorded as S11.

[0067] Example 12

[0068] This embodiment is the same as embodiment 11, except that the auxiliary agent is EDTA, which is denoted as S12.

[0069] Embodiment 13

[0070] This embodiment is the same as embodiment 11, except that the auxiliary agent is TMEDA, denoted as S13.

[0071] Embodiment 14

[0072] This embodiment is the same as embodiment 11, except that the auxiliary agent is triethylamine, which is denoted as S14.

[0073] Embodiment 15

[0074] This embodiment is the same as Embodiment 11, except that the molar ratio of the auxiliary agent sodium sulfide to the metal platinum is 0.01:1, denoted as S15.

[0075] Example 16

[0076] This embodiment is the same as Embodiment 11, except that the molar ratio of the auxiliary agent sodium sulfide to the metal platinum is 0.1:1, denoted as S16.

[0077] Application Examples

[0078] This embodiment provides a method for continuous production of phenylhydroxylamine compounds, comprising:

[0079] Step 1, mixing a nitrobenzene compound with an organic solvent to obtain a reaction solution;

[0080] Step 2: Fill any catalyst of Examples 1 to 16 into a fixed bed reactor;

[0081] Step 3: Pass the reaction liquid and nitrogen-hydrogen mixed gas into a fixed bed tubular reactor containing a catalyst bed, maintain the pressure and temperature in the fixed bed tubular reactor, take samples for gas chromatography detection, and post-treat the reaction liquid of the system to obtain the product.

[0082] The composition and dosage of the raw materials and solvent, the pressure and temperature in the fixed bed reactor, and the corresponding product yield and selectivity are shown in Table 1.

[0083] Table 1 Raw material and solvent composition and dosage, pressure and temperature in fixed bed reactor, and corresponding product yield and selectivity

[0084]

[0085]

[0086]

[0087]

[0088]

[0089] Based on Table 1, during the reaction, the pressure in the reactor was 0.5-0.8 MPa, the temperature was 5°C-20°C, the hydrogen-nitrogen ratio was 10%-30%, and the reaction space velocity was 0.3 g / g·h -1 ~0.5g / g·h -1 ; wherein the nitrobenzene compound includes nitrobenzene or substituted nitrobenzene, and the substituted nitrobenzene includes 2-methylnitrobenzene, 2-fluoronitrobenzene, 2-chloronitrobenzene, 4-fluoronitrobenzene, 4-methylnitrotoluene, 4-nitrophenol, 3-chloronitrobenzene or 2,6-dimethylnitrotoluene; the organic solvent includes ethanol, tetrahydrofuran, 1,4-dioxane or 1,2-dichloroethane; the mass ratio of the organic solvent to the raw material is (10-20):1; the reaction results are shown in Table 1. Based on Table 1, it can be seen that the catalyst of the present invention can be used to prepare phenylhydroxylamine compounds from nitrobenzene compounds, with a conversion rate of more than 90%, up to 100%, and a high selectivity of more than 90%.

[0090] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent structural change made to the above embodiment according to the technical essence of the invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A catalyst for preparing phenylhydroxylamine compounds, characterized in that: The catalyst comprises a carrier and an active noble metal loaded on the carrier. The active noble metal is platinum. The mass percentage of the active noble metal in the catalyst is 0.5% to 1%. The raw material of the carrier is coconut shell columnar activated carbon.

2. A catalyst for preparing phenylhydroxylamine compounds according to claim 1, characterized in that: The coconut shell columnar activated carbon has a diameter of 1.5 mm to 2.2 mm, a length of 2 mm to 4 mm, and a specific surface area of ​​1000 m 2 / g~1200m 2 / g, pore volume is 0.85cm 3 / g~0.95cm 3 / g.

3. A method for preparing the catalyst for preparing phenylhydroxylamine compounds as claimed in claim 1, characterized in that: The following steps are involved: Step 1: Immerse coconut shell columnar activated carbon in a hydrogen peroxide solution at a temperature of 50°C to 60°C for 4 to 5 hours, wash with water until the pH is greater than 5, and dry to a constant weight to obtain a carrier; Step 2: dissolving a soluble salt of an active noble metal in dilute nitric acid to obtain a solution A, adding the support in step 1 to the solution A, and impregnating the solution under stirring at room temperature for 20 h to 24 h to obtain an impregnated system; Step 3: at 0°C to 5°C, add the solution of the alkali metal reducing agent and the auxiliary agent dropwise to the impregnated system of step 2, let stand at 0°C to 5°C for 2h to 3h, wash with water, vacuum dry at 60°C to 70°C for 3h to 5h, heat to 110°C to 120°C, continue vacuum drying to constant weight, and cool naturally to obtain a catalyst precursor; Step 4: subjecting the catalyst precursor in step 3 to hydrogen reduction to obtain a catalyst for preparing phenylhydroxylamine compounds.

4. The method according to claim 3, characterized in that The drying temperature in step 1 is 100° C. to 120° C.; the mass concentration of dilute nitric acid in step 2 is 0.5% to 1%, and the mass of the dilute nitric acid is 2 to 4 times the total mass of the soluble salt of the active precious metal and the carrier, and the soluble salt of the active precious metal is a nitrate of the active precious metal or a chloride of the active precious metal.

5. The method according to claim 3, characterized in that: In step 3, the alkali metal-containing reducing agent is sodium borohydride or sodium formate, the auxiliary agent is a sulfur-containing compound or a nitrogen-containing compound, the molar ratio of the alkali metal-containing reducing agent to the active precious metal is (4-5):1, the molar ratio of the auxiliary agent to the active precious metal is (0.01-0.1):1, and the mass percentage of the alkali metal-containing reducing agent in the solution of the alkali metal-containing reducing agent and the auxiliary agent is 1% to 3%; in step 3, washing with water until the pH of the system is 8-10.

6. The method according to claim 5, characterized in that The sulfur-containing compound includes sodium sulfide, sodium sulfite or thiourea, and the nitrogen-containing compound includes triethylamine, ethylenediaminetetraacetic acid (EDTA) or N,N,N',N'-tetramethylethylenediamine (TMEDA).

7. The method according to claim 3, characterized in that The hydrogen reduction in step 4 includes: in the presence of hydrogen, heating the catalyst precursor to 300° C. to 350° C. at a heating rate of 2° C. / min to 3° C. / min, maintaining the temperature for 2 h to 4 h, and cooling naturally.

8. A process for preparing phenylhydroxylamine compounds using the catalyst as claimed in claim 1, characterized in that: The reactor used in the process is a fixed bed tubular reactor, and the process method comprises: mixing nitrobenzene compounds with a solvent, introducing a mixed gas of hydrogen and nitrogen, and carrying out a catalytic reaction under the action of the catalyst; the reaction pressure is 0.5MPa to 0.8MPa, the temperature is 5°C to 20°C, and the reaction space velocity is 0.3g / g·h -1 ~0.5g / g·h -1 .

9. The process according to claim 8, characterized in that: The volume percentage of hydrogen in the mixed gas of hydrogen and nitrogen is 10% to 30%; the reaction solvent is one or more of tetrahydrofuran, dioxane, ethanol and 1,2-dichloroethane, and the mass ratio of the reaction solvent to the nitrobenzene compound is (10 to 20):

1.

10. The process according to claim 8, characterized in that: The nitrobenzene compound is nitrobenzene or substituted nitrobenzene, and the substituent of the substituted nitrobenzene can be a single or multiple substituents at the ortho, meta, or para position of nitrobenzene, and the substituent can be an alkyl, aryl, halogen, or heteroatom substituent.

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