Catalyst and method for preparing 3-methyl-2-aminobenzoic acid through continuous catalytic hydrogenation

Abstract

The invention discloses a catalyst and method for preparing 3-methyl-2-aminobenzoic acid through continuous catalytic hydrogenation, and the method comprises the following steps: pretreating an activated carbon carrier by using pretreatment reagents such as nitric acid and hydrogen peroxide to remove impurities in the carrier; modifying the carrier by using an auxiliary component 1 such as sodium carbonate, stannic chloride, potassium carbonate and lanthanum nitrate, and then roasting and reaming; and finally, active components such as platinum chloride and palladium chloride are mixed and impregnated with an auxiliary component 2 such as oxalic acid, polyethylene glycol-400, sodium metavanadate and polyvinylpyrrolidone, the auxiliary component 2 promotes dispersion of the active metal, and the auxiliary component 2 and the auxiliary component 1 have a synergistic effect, so that the active metal is loaded more uniformly and firmly, and the obtained catalyst has higher activity and selectivity and longer service life. The catalyst is applied to preparation of 3-methyl-2-aminobenzoic acid through catalytic hydrogenation in a fixed bed reactor, the reaction can be continuously and automatically controlled, the three wastes in the reaction process are few, the yield of a target product is high, the service life of the catalyst is long, and the catalyst is suitable for industrial production.

Description

Technical Field

[0001] The invention belongs to the technical field of catalytic hydrogenation, and specifically relates to a catalyst for preparing 3-methyl-2-aminobenzoic acid by continuous catalytic hydrogenation, and a catalytic hydrogenation method using the catalyst. Background Art

[0002] 3-Methyl-2-aminobenzoic acid is an important chemical intermediate, mainly used in the fields of medicine, dyes and pesticides. 3-Methyl-2-aminobenzoic acid can be used as a raw material to prepare the environmentally friendly insecticide chlorantraniliprole, which has extremely high insecticidal activity and extremely low toxicity to mammals and birds. It is used in large quantities due to its high-quality properties, so the efficient preparation of 3-methyl-2-aminobenzoic acid is also valued by everyone.

[0003] At present, most of the industry uses meta-xylene as a raw material to prepare 3-methyl-2-aminobenzoic acid through oxidation, nitration, and nitro reduction. Patent CN 111732520 B discloses a method for preparing 3-methyl-2-aminobenzoic acid. The patent uses meta-xylene as a raw material, and obtains 3-methyl-2-aminobenzoic acid through chlorination, oxidation, and amination. The catalyst involved is cobalt manganese copper salt. The reaction process is a multi-step intermittent chemical synthesis, the process is cumbersome, and more acid by-products are produced. Patent application CN 110372526A discloses a method for preparing 3-methyl-2-aminobenzoic acid. The patent oxidizes and aminates 2-chloro-meta-xylene under a catalytic system of sodium acetate, cuprous chloride, and sodium carbonate to obtain 3-methyl-2-aminobenzoic acid. The reaction process is an intermittent reaction with a low degree of automation, and the highest yield is 93.1%. Patent application CN 117820140 A discloses a method for preparing 3-methyl-2-aminobenzoic acid. The patent uses 3-methyl-2-nitrobenzoic acid as a raw material, adds a composite catalyst, additives, solvents, etc. to the reaction system for intermittent reaction, resulting in cumbersome subsequent separation. Therefore, it is of great significance to develop a green, environmentally friendly, simple and safe process. Summary of the invention

[0004] In view of the defects of the prior art, the present invention provides a catalyst having high activity, selectivity and stability for preparing 3-methyl-2-aminobenzoic acid by continuous catalytic hydrogenation, and a method for preparing 3-methyl-2-aminobenzoic acid by continuous catalytic hydrogenation using the catalyst.

[0005] The catalyst for preparing 3-methyl-2-aminobenzoic acid by continuous catalytic hydrogenation provided by the present invention is prepared by impregnating an auxiliary component 1, an auxiliary component 2 and an active component on an activated carbon carrier; the auxiliary component 1 is any one or more of sodium carbonate, tin chloride, stannous chloride, potassium carbonate, potassium chloride and lanthanum nitrate; the auxiliary component 2 is any one of oxalic acid, polyethylene glycol-400, sodium metavanadate and polyvinyl pyrrolidone; and the active component is any one of platinum chloride, platinum nitrate, palladium chloride and palladium nitrate.

[0006] The preparation method of the catalyst of the present invention comprises the following steps:

[0007] Step 1: Boil the activated carbon carrier with a pretreatment reagent for 1 to 5 hours, wash with water until neutral, and dry to obtain a pretreated carrier; the pretreatment reagent is selected from any one of a nitric acid aqueous solution with a mass concentration of 5% to 30%, a hydrogen peroxide aqueous solution with a mass concentration of 5% to 30%, and an acetic acid aqueous solution with a mass concentration of 5% to 30%.

[0008] Step 2: The auxiliary agent component 1 is impregnated and loaded on the pretreated carrier, and after drying and calcination, a promoter is obtained.

[0009] Step 3: impregnate the co-catalyst with the loaded active component and the auxiliary component 2, and obtain the catalyst after drying and reduction.

[0010] Furthermore, it is preferred that the auxiliary component 1 is any one or more of sodium carbonate, tin chloride, potassium carbonate, and lanthanum nitrate; the auxiliary component 2 is any one of oxalic acid, polyethylene glycol-400, and sodium metavanadate; and the active component is any one of platinum chloride and platinum nitrate.

[0011] In the above preparation method, the amount of metal elements added in the auxiliary component 1 is preferably 0.1% to 20% of the mass of the catalyst; the amount of metal elements added in the active component is preferably 0.1% to 10% of the mass of the catalyst; and the amount of auxiliary component 2 is preferably 0.1% to 10% of the mass of the catalyst.

[0012] Furthermore, in the above preparation method, it is more preferred that the amount of metal elements added in the auxiliary component 1 is 1% to 5% of the mass of the catalyst; the amount of metal elements added in the active component is 0.5% to 3% of the mass of the catalyst; and the amount of auxiliary component 2 is 1% to 5% of the mass of the catalyst.

[0013] In the above step 1, the pretreatment reagent is preferably selected from any one of a nitric acid aqueous solution with a mass concentration of 5% to 10%, a hydrogen peroxide aqueous solution with a mass concentration of 5% to 10%, and an acetic acid aqueous solution with a mass concentration of 5% to 10%.

[0014] In the above step 1, the amount of the pretreatment reagent added is preferably 2 to 5 times the mass of the activated carbon carrier.

[0015] In the above steps 2 and 3, the solid-liquid ratio of the impregnation is preferably 1:1.5-3, the impregnation time is 5-12 hours, and the impregnation is followed by drying in an oven at 100-150°C.

[0016] In the above step 2, the calcination is carried out under N2 atmosphere, preferably the calcination temperature is 450-600°C, the calcination time is 2-5h, and the N2 flow rate is 100-500mL·min -1 .

[0017] In the above step 3, reduction is carried out under H2 atmosphere, preferably at a reduction temperature of 200-400°C, a reduction time of 1-5h, and a H2 flow rate of 100-500mL·min -1 .

[0018] The present invention also provides a method for preparing 3-methyl-2-aminobenzoic acid by continuous catalytic hydrogenation, which specifically comprises: using 3-methyl-2-nitrobenzoic acid as a raw material, the reaction equipment being a fixed bed reactor, loading the catalyst according to any one of claims 1 to 7 into the middle of a reaction tube, the reaction temperature being 70 to 150° C., the reaction pressure being 0.5 to 3 MPa, and the reaction mass space velocity being 0.1 to 2 h -1 , the hydrogen material molar ratio is 5 to 20.

[0019] In the above method for preparing 3-methyl-2-aminobenzoic acid by continuous catalytic hydrogenation, the preferred reaction temperature is 80-130°C, the reaction pressure is 1-2 MPa, and the reaction mass space velocity is 0.5-1.5 h -1 , the hydrogen-to-material molar ratio is 8-15.

[0020] The beneficial effects of the present invention are as follows:

[0021] 1. The present invention first pre-treats the activated carbon carrier with a pre-treatment reagent to remove impurities in the carrier, which is conducive to better adsorption of the active component on the carrier. Then, the carrier is modified with an auxiliary component 1, which is conducive to anchoring with the active metal. Nitrogen roasting and pore expansion are used to facilitate timely desorption of the product and avoid excessive reaction. Finally, the active component and auxiliary component 2 are mixed and impregnated. Auxiliary component 2 promotes the dispersion of active metals and synergizes with auxiliary component 1 to make the active metal load more uniform and firm, so that the obtained catalyst has higher activity, selectivity and life.

[0022] 2. The catalyst of the present invention is used for catalytic hydrogenation in a fixed bed reactor to prepare 3-methyl-2-aminobenzoic acid. The reaction can be continuous and automatically controlled, with better safety performance, less three wastes in the reaction process, high yield of target product, and good catalyst life. It is suitable for industrial production and has good economic and social benefits. DETAILED DESCRIPTION

[0023] The present invention is further described in detail below in conjunction with the embodiments, but the protection scope of the present invention is not limited to these embodiments.

[0024] Example 1

[0025] The catalyst of the present embodiment is prepared by impregnating tin chloride, oxalic acid and platinum chloride on an activated carbon carrier; based on the mass of the catalyst as 100%, the amount of Sn element added to the tin chloride is 1% of the mass of the catalyst, the amount of Pt element added to the platinum chloride is 0.5% of the mass of the catalyst, and the amount of oxalic acid added is 1% of the mass of the catalyst; the preparation method of the catalyst comprises the following steps:

[0026] Step 1: Place 97.5 g of activated carbon carrier and 300 g of 10% nitric acid aqueous solution in a beaker and boil for 3 hours, centrifuge, wash the black precipitate with water until it is neutral, and dry at 120°C to obtain a pretreated carrier.

[0027] Step 2: Add 2.19g of tin chloride to 200g of 5% hydrochloric acid aqueous solution and stir to dissolve, then add the pretreated carrier in step 1 and soak for 10h. After the adsorption is completed, filter out the supernatant, dry it in an oven at 120℃, and place it in a tube furnace at a N2 flow rate of 300mL·min -1 The catalyst was calcined at 500 °C in a N2 atmosphere for 3 h to obtain a co-catalyst 1% Sn / C.

[0028] Step 3: Dissolve 5 mL of 0.1 g / mL platinum chloride aqueous solution and 1 g of oxalic acid in 200 g of deionized water, then add the co-catalyst 1% Sn / C from step 2, and soak for 10 h. After the adsorption is completed, filter out the supernatant, dry it in an oven at 120 °C, and place it in a H2 flow rate of 300 mL min -1 The catalyst was reduced at 280 °C in a H2 atmosphere for 3 h, and was recorded as 0.5% Pt + 1% oxalic acid / 1% Sn / C.

[0029] Example 2

[0030] The catalyst of the present embodiment is prepared by impregnating sodium carbonate, sodium metavanadate and platinum chloride on an activated carbon carrier; based on the mass of the catalyst as 100%, the amount of Na element added in the sodium carbonate is 3% of the mass of the catalyst, the amount of Pt element added in the platinum chloride is 1% of the mass of the catalyst, and the amount of sodium metavanadate added is 3% of the mass of the catalyst carrier; the preparation method of the catalyst comprises the following steps:

[0031] Step 1: Place 93 g of activated carbon carrier and 400 g of 5% hydrogen peroxide aqueous solution in a beaker and boil for 5 hours, centrifuge, wash the black precipitate with water until it is neutral, and dry at 150°C to obtain a pretreated carrier.

[0032] Step 2: Add 6.91g of sodium carbonate to 250g of deionized water and stir to dissolve, then add the pretreated carrier in step 1 and soak for 8h. After the adsorption is completed, filter out the supernatant, dry it in an oven at 120℃, and place it in a tube furnace at a N2 flow rate of 200mL·min -1 The catalyst was calcined at 600 °C in a N2 atmosphere for 2 h to obtain a co-catalyst 3% Na / C.

[0033] Step 3: Dissolve 10 mL of 0.1 g / mL platinum chloride aqueous solution and 3 g of sodium metavanadate in 250 g of deionized water, then add the co-catalyst 3% Na / C from step 2, and soak for 12 hours. After the adsorption is completed, filter out the supernatant, dry it in an oven at 120 ° C, and place it in a H2 flow rate of 400 mL min -1 The catalyst was reduced at 300°C in a H2 atmosphere for 3 h, and was recorded as 1% Pt + 3% sodium metavanadate / 3% Na / C.

[0034] Example 3

[0035] The catalyst of this embodiment is prepared by impregnating lanthanum nitrate, polyethylene glycol-400 and platinum chloride on an activated carbon carrier; based on the mass of the catalyst as 100%, the amount of La element added to the lanthanum nitrate is 2% of the mass of the catalyst, the amount of Pt element added to the platinum chloride is 0.1% of the mass of the catalyst, and the amount of polyethylene glycol-400 added is 1% of the mass of the catalyst; the preparation method of the catalyst comprises the following steps:

[0036] Step 1: Place 96.9 g of activated carbon carrier and 450 g of 5% acetic acid aqueous solution in a beaker and boil for 5 hours, centrifuge, wash the black precipitate with water until it is neutral, and dry at 150°C to obtain a pretreated carrier.

[0037] Step 2: Add 6.23g of lanthanum nitrate hexahydrate to 250g of deionized water and stir to dissolve, then add the pretreated carrier in step 1 and soak for 12h. After the adsorption is completed, filter out the supernatant, dry it in an oven at 120℃, and place it in a tube furnace at a N2 flow rate of 100mL·min -1 The catalyst was calcined at 450 °C in a N2 atmosphere for 5 h to obtain a co-catalyst 2% La / C.

[0038] Step 3: Dissolve 1 mL of 0.1 g / mL platinum chloride solution and 1 g of polyethylene glycol-400 in 300 g of deionized water, then add the co-catalyst 2% La / C from step 2, and soak for 12 hours. After the adsorption is completed, filter out the supernatant, dry it in an oven at 120°C, and place it in a H2 flow rate of 200 mL min -1 The catalyst was reduced at 400°C in a H2 atmosphere for 1 h, and was recorded as 0.1% Pt + 1% polyethylene glycol-400 / 2% La / C.

[0039] Example 4

[0040] The catalyst of this embodiment is prepared by impregnating potassium carbonate, oxalic acid and platinum chloride on an activated carbon carrier; based on the mass of the catalyst as 100%, the amount of K element added in the potassium carbonate is 0.1% of the mass of the catalyst, the amount of Pt element added in the platinum chloride is 3% of the mass of the catalyst, and the amount of oxalic acid added is 5% of the mass of the catalyst; the preparation method of the catalyst comprises the following steps:

[0041] Step 1: Place 91.9 g of activated carbon carrier and 300 g of 5% nitric acid aqueous solution in a beaker and boil for 3 hours, centrifuge, wash the black precipitate with water until it is neutral, and dry at 150°C to obtain a pretreated carrier.

[0042] Step 2: Add 0.18g potassium carbonate to 250g deionized water and stir to dissolve, then add the pretreated carrier in step 1 and soak for 5h. After the adsorption is completed, filter out the supernatant, dry it in an oven at 120℃, and place it in a tube furnace at a N2 flow rate of 200mL·min -1 The catalyst was calcined at 500 °C in a N2 atmosphere for 5 h to obtain a promoter with a K / C content of 0.1%.

[0043] Step 3: Dissolve 30 mL of 0.1 g / mL platinum chloride aqueous solution and 5 g of oxalic acid in 250 g of deionized water, then add the co-catalyst 0.1% K / C from step 2, and soak for 12 hours. After the adsorption is completed, filter out the supernatant, dry it in an oven at 120 ° C, and place it in a H2 flow rate of 500 mL min -1 The catalyst was reduced at 300 °C in a H2 atmosphere for 5 h, and was recorded as 3% Pt + 5% oxalic acid / 0.1% K / C.

[0044] Example 5

[0045] The catalyst of the present embodiment is prepared by impregnating tin chloride, sodium metavanadate and platinum chloride on an activated carbon carrier; based on the mass of the catalyst as 100%, the amount of Sn element added to the tin chloride is 3% of the mass of the catalyst, the amount of Pt element added to the platinum chloride is 1% of the mass of the catalyst, and the amount of sodium metavanadate added is 1% of the mass of the catalyst; the preparation method of the catalyst comprises the following steps:

[0046] Step 1: Place 95g of activated carbon carrier and 300g of 10% nitric acid aqueous solution in a beaker and boil for 3h, centrifuge, wash the black precipitate with water until it is neutral, and dry at 120°C to obtain the pretreated carrier.

[0047] Step 2: Add 6.58g of tin chloride to 200g of 10% hydrochloric acid aqueous solution and stir to dissolve, then add the pretreated carrier in step 1 and soak for 10h. After the adsorption is completed, filter out the supernatant, dry it in an oven at 120℃, and place it in a tube furnace at a N2 flow rate of 300mL·min -1 The catalyst was calcined at 500 °C in a N2 atmosphere for 3 h to obtain a co-catalyst 3% Sn / C.

[0048] Step 3: Dissolve 10 mL of 0.1 g / mL platinum chloride aqueous solution and 1 g of sodium metavanadate in 200 g of deionized water, then add the co-catalyst 3% Sn / C from step 2, and soak for 10 h. After the adsorption is completed, filter out the supernatant, dry it in an oven at 120 °C, and place it in a H2 flow rate of 300 mL min -1 The catalyst was reduced at 320°C in a H2 atmosphere for 2 h, and was recorded as 1% Pt + 1% sodium metavanadate / 3% Sn / C.

[0049] Example 6

[0050] The catalyst of this embodiment is prepared by impregnating lanthanum nitrate, polyethylene glycol-400 and platinum nitrate on an activated carbon carrier; based on the mass of the catalyst as 100%, the amount of La element added to the lanthanum nitrate is 5% of the mass of the catalyst, the amount of Pt element added to the platinum nitrate is 0.5% of the mass of the catalyst, and the amount of polyethylene glycol-400 added is 0.5% of the mass of the catalyst; the preparation method of the catalyst comprises the following steps:

[0051] Step 1: Place 94 g of activated carbon carrier and 300 g of 10% nitric acid aqueous solution in a beaker and boil for 3 hours, centrifuge, wash the black precipitate with water until it is neutral, and dry at 120°C to obtain a pretreated carrier.

[0052] Step 2: Add 15.59 g of lanthanum nitrate hexahydrate to 200 g of deionized water and stir to dissolve, then add the pretreated carrier in step 1 and soak for 10 hours. After the adsorption is completed, filter out the supernatant, dry it in an oven at 120°C, and place it in a tube furnace at a N2 flow rate of 300 mL min -1 The catalyst was calcined at 500 °C in a N2 atmosphere for 3 h to obtain a co-catalyst with 5% La / C.

[0053] Step 3: Dissolve 5 mL of 0.1 g / mL platinum nitrate aqueous solution and 0.5 g of polyethylene glycol-400 in 200 g of deionized water, then add the co-catalyst 5% La / C from step 2, and soak for 10 h. After the adsorption is completed, filter out the supernatant, dry it in an oven at 120 ° C, and place it in a H2 flow rate of 300 mL min -1 The catalyst was reduced at 300°C in a H2 atmosphere for 2 h, and was recorded as 0.5% Pt + 0.5% polyethylene glycol-400 / 5% La / C.

[0054] Example 7

[0055] The catalyst of this embodiment is prepared by impregnating potassium carbonate, sodium metavanadate and platinum nitrate on an activated carbon carrier; based on the mass of the catalyst as 100%, the amount of K element added in the potassium carbonate is 0.5% of the mass of the catalyst, the amount of Pt element added in the platinum nitrate is 2% of the mass of the catalyst, and the amount of sodium metavanadate added is 5% of the mass of the catalyst; the preparation method of the catalyst comprises the following steps:

[0056] Step 1: Place 92.5 g of activated carbon carrier and 300 g of 10% acetic acid aqueous solution in a beaker and boil for 3 h, centrifuge, wash the black precipitate with water until it is neutral, and dry at 120°C to obtain a pretreated carrier.

[0057] Step 2: Add 0.88g potassium carbonate to 250g deionized water and stir to dissolve, then add the pretreated carrier in step 1 and soak for 10h. After the adsorption is completed, filter out the supernatant, dry it in an oven at 120℃, and place it in a tube furnace at a N2 flow rate of 300mL·min -1 The catalyst was calcined at 500 °C in a N2 atmosphere for 3 h to obtain a promoter with a K / C content of 0.5%.

[0058] Step 3: Dissolve 20 mL of 0.1 g / mL platinum nitrate aqueous solution and 5 g of sodium metavanadate in 250 g of deionized water, then add the co-catalyst 0.5% K / C from step 2, and soak for 10 h. After the adsorption is completed, filter out the supernatant, dry it in an oven at 120 ° C, and place it in a H2 flow rate of 300 mL min -1 The catalyst was reduced at 350°C in a H2 atmosphere for 2 h, and was recorded as 2% Pt + 5% sodium metavanadate / 0.5% K / C.

[0059] Comparative Example 1

[0060] Dissolve 5 mL of 0.1 g / mL platinum chloride aqueous solution in 200 g of deionized water, add 99.5 g of activated carbon carrier, and soak for 10 h. After adsorption, filter out the supernatant, dry it in an oven at 120 °C, and place it in a H2 flow rate of 300 mL min -1 The catalyst was reduced at 280 °C in a H2 atmosphere for 3 h, and was recorded as 0.5% Pt / C-1.

[0061] Comparative Example 2

[0062] Step 1: Place 99.5 g of activated carbon carrier and 300 g of 10% nitric acid aqueous solution in a beaker and boil for 3 hours, centrifuge, wash the black precipitate with water until it is neutral, and dry at 120°C to obtain a pretreated carrier.

[0063] Step 2: Dissolve 5 mL of 0.1 g / mL platinum chloride aqueous solution in 200 g of deionized water, add the pretreated carrier from step 1, and soak for 10 h. After adsorption, filter out the supernatant, dry it in an oven at 120 °C, and place it under a H2 flow rate of 300 mL min. -1 The catalyst was reduced at 280 °C in a H2 atmosphere for 3 h, and was recorded as 0.5% Pt / C-2.

[0064] 3-methyl-2-aminobenzoic acid was prepared by continuous catalytic hydrogenation using the catalysts prepared in Examples 1 to 7 and Comparative Examples 1 and 2. The specific method is as follows: 3-methyl-2-nitrobenzoic acid was used as a raw material, the reaction equipment was a fixed bed reactor, the catalyst was loaded into the middle of the reaction tube, the raw material was dissolved in DMF and then reacted with hydrogen into the reactor. The specific reaction conditions and results are shown in Table 1.

[0065] Table 1 Reaction conditions and results

[0066]

[0067]

[0068] As can be seen from Table 1, the catalyst prepared by the present invention has a higher yield and longer life and stability when applied to the continuous catalytic hydrogenation to prepare 3-methyl-2-aminobenzoic acid.

[0069] The above description is only a detailed description of the content of the present invention, and does not limit the present invention in any way. Any simple modification or change made according to the technical requirements provided by the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A catalyst for preparing 3-methyl-2-aminobenzoic acid by continuous catalytic hydrogenation, characterized in that: The catalyst is prepared by impregnating and loading an active component on an activated carbon carrier with an auxiliary component 1, an auxiliary component 2, and an active component; the auxiliary component 1 is any one or more of sodium carbonate, tin chloride, stannous chloride, potassium carbonate, potassium chloride, and lanthanum nitrate; the auxiliary component 2 is any one of oxalic acid, polyethylene glycol-400, sodium metavanadate, and polyvinyl pyrrolidone; the active component is any one of platinum chloride, platinum nitrate, palladium chloride, and palladium nitrate; The preparation method of the catalyst comprises the following steps: Step 1: Boil the activated carbon carrier with a pretreatment reagent for 1 to 5 hours, wash with water until neutral, and dry to obtain a pretreated carrier; the pretreatment reagent is selected from any one of a nitric acid aqueous solution with a mass concentration of 5% to 30%, a hydrogen peroxide aqueous solution with a mass concentration of 5% to 30%, and an acetic acid aqueous solution with a mass concentration of 5% to 30%; Step 2: impregnating the auxiliary agent component 1 into the pretreated carrier, drying and calcining to obtain the auxiliary catalyst; Step 3: impregnating the active component and the auxiliary component 2 with the co-catalyst, and obtaining the catalyst after drying and reduction; The amount of the metal element added in the auxiliary component 1 is 0.1% to 20% of the mass of the catalyst; The amount of metal elements added to the active component is 0.1% to 10% of the catalyst mass; The addition amount of the auxiliary component 2 is 0.1% to 10% of the catalyst mass.

2. The catalyst for preparing 3-methyl-2-aminobenzoic acid by continuous catalytic hydrogenation according to claim 1, characterized in that: The auxiliary component 1 is any one or more of sodium carbonate, tin chloride, potassium carbonate, and lanthanum nitrate; the auxiliary component 2 is any one of oxalic acid, polyethylene glycol-400, and sodium metavanadate; and the active component is any one of platinum chloride and platinum nitrate.

3. The catalyst for preparing 3-methyl-2-aminobenzoic acid by continuous catalytic hydrogenation according to claim 1, characterized in that: The amount of metal elements added to the auxiliary component 1 is 1% to 5% of the mass of the catalyst; the amount of metal elements added to the active component is 0.5% to 3% of the mass of the catalyst; and the amount of auxiliary component 2 is 1% to 5% of the mass of the catalyst.

4. The catalyst for preparing 3-methyl-2-aminobenzoic acid by continuous catalytic hydrogenation according to claim 1, characterized in that: In step 1, the pretreatment reagent is selected from any one of a nitric acid aqueous solution with a mass concentration of 5% to 10%, a hydrogen peroxide aqueous solution with a mass concentration of 5% to 10%, and an acetic acid aqueous solution with a mass concentration of 5% to 10%.

5. The catalyst for preparing 3-methyl-2-aminobenzoic acid by continuous catalytic hydrogenation according to claim 1, characterized in that: In step 1, the amount of the pretreatment reagent added is 2 to 5 times the mass of the activated carbon carrier.

6. The catalyst for preparing 3-methyl-2-aminobenzoic acid by continuous catalytic hydrogenation according to claim 1, characterized in that: In step 2 and step 3, the solid-liquid ratio of the impregnation is 1:1.5-3, the impregnation time is 5-12 hours, and after impregnation, the mixture is placed in an oven at 100-150°C for drying.

7. The catalyst for preparing 3-methyl-2-aminobenzoic acid by continuous catalytic hydrogenation according to claim 1, characterized in that: In step 2, the calcination is carried out under N2 atmosphere at a temperature of 450-600°C, a time of 2-5h, and a N2 flow rate of 100-500mL·min -1 .

8. The catalyst for preparing 3-methyl-2-aminobenzoic acid by continuous catalytic hydrogenation according to claim 1, characterized in that: In step 3, reduction is carried out under H2 atmosphere, the reduction temperature is 200-400°C, the reduction time is 1-5h, and the H2 flow rate is 100-500mL·min -1 .

9. A method for preparing 3-methyl-2-aminobenzoic acid by continuous catalytic hydrogenation, characterized in that: 3-Methyl-2-nitrobenzoic acid is used as a raw material, the reaction equipment is a fixed bed reactor, the catalyst described in any one of claims 1 to 7 is loaded into the middle of the reaction tube, the reaction temperature is 70 to 150° C., the reaction pressure is 0.5 to 3 MPa, and the reaction mass space velocity is 0.1 to 2 h -1 , the hydrogen-to-material molar ratio is 5-20.

10. The method for preparing 3-methyl-2-aminobenzoic acid by continuous catalytic hydrogenation according to claim 9, characterized in that: The reaction temperature is 80-130°C, the reaction pressure is 1-2MPa, and the reaction mass space velocity is 0.5-1.5h -1 , the hydrogen-to-material molar ratio is 8-15.

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