A method for preparing nano metal passivator

Abstract

The present application relates to the technical field of metal passivators, and specifically discloses a method for preparing a nano metal passivator. A method for preparing a nano metal passivator comprises the following steps: first preparing a complex dispersant with good stability and dispersibility, and then mixing the complex dispersant with an effective metal to prepare a nano metal passivator. The nano metal passivator prepared in the present application has the advantages of good dispersibility and high effective ingredients, and can effectively improve the activity of a catalytic cracking catalyst.

Description

Technical Field

[0001] The present application relates to the technical field of metal passivators, and more specifically, to a method for preparing a nano metal passivator. Background Art

[0002] During the catalytic cracking production process, heavy metal elements in the crude oil are deposited on the catalyst surface, causing catalyst poisoning and deactivation, resulting in an increase in the yield of product coke and dry gas, and a decrease in the yield of light oil.

[0003] The pollution of catalytic cracking catalysts is mainly nickel and vanadium. Nickel and vanadium exist in petroleum in the form of porphyrin and non-porphyrin complexes. During the processing, most of these compounds enter heavy distillate oils such as atmospheric and vacuum residues. When secondary processing is carried out, the porphyrin nickel deposited on the catalyst is oxidized at high temperature and deposited on the catalyst in an oxidized state. When the regenerated catalyst is returned to the reactor, part of the high-valent nickel oxide is easily reduced. The reduced low-valent nickel plays a dehydrogenation role in the catalytic cracking process, increasing the hydrogen content and coke content in the dry gas; the porphyrin vanadium adsorbed on the catalyst decomposes rapidly in the oxidizing environment of the regenerator and is eventually converted into vanadium pentoxide with a melting point. In the oxidizing atmosphere of the regenerator and the presence of water vapor, the molten vanadium pentoxide will migrate to the catalyst surface, block the pores or enter the catalyst, neutralize the catalyst acid center, and cause the catalyst activity to decrease or deactivate.

[0004] There are many methods to inhibit heavy metal pollution, such as crude oil pretreatment, catalyst demetallization, use of metal passivators, etc. Among them, the use of metal passivators has been proven to be an effective method.

[0005] A Chinese patent application document with application publication number CN106475155A discloses a metal passivator and a preparation method thereof. The preparation method of the metal passivator in the patent application document is as follows: after mixing an organic amine and a solvent, a metal oxide is added, the temperature is raised to 90°C, an oxidant is added dropwise to allow the oxidant and the metal oxide to react, and the reaction temperature is controlled at 90-120°C; after the reaction is completed, the reaction liquid is filtered to remove impurities to obtain the metal passivator.

[0006] In the above documents, the active metal components are dispersed in the metal passivator solution through the interaction between organic amines and active metal components. However, due to the single function of organic amines, the dispersibility and content of active metal components cannot be improved effectively. Summary of the invention

[0007] In order to further improve the dispersibility and effective component content of the nano-metal passivator, and thus improve the activity of the catalytic cracking catalyst, the present application provides a method for preparing the nano-metal passivator.

[0008] The present application provides a method for preparing a nano-metal passivator, which adopts the following technical solution:

[0009] A method for preparing a nano metal passivator comprises the following steps:

[0010] (1) Evenly mix p-phenylenediamine and formaldehyde aqueous solution, then add phosphorus trichloride and heat to react to obtain complex component a;

[0011] (2) Mix acetic acid and water evenly, add phosphorus trichloride, stir to react, add ammonia water to adjust the pH, then add p-aminophenylethanol, reflux to react, after the reaction is completed, cool, add complexing component a and mix evenly to obtain a complexing dispersant;

[0012] (3) Mix antimony trioxide and nitric acid, add a complexing dispersant, adjust with alkali solution, stir to react, add dimethylformamide, and evenly disperse to obtain a passivating agent A;

[0013] (4) Mix lanthanum oxide and nitric acid, add a complexing dispersant, adjust with alkali solution, stir to react, add dimethylformamide, disperse evenly, and obtain passivating agent B;

[0014] (5) Passivator A and passivator B are mixed to obtain a nano metal passivator.

[0015] By adopting the above technical scheme, a complex dispersant with good thermal stability and dispersibility is prepared, in which the phosphonic acid group has a good complexing ability for antimony ions and lanthanum ions, which increases the solubility of antimony ions and lanthanum ions in the solution, and by introducing a long chain of terminal hydroxyl groups, the affinity of the active ingredients of the nanometal passivator and the catalyst is increased, thereby improving the passivation ability of the nanometal passivator.

[0016] Preferably, in step (1), the mass ratio of p-phenylenediamine, formaldehyde aqueous solution and phosphorus trichloride is (0.24-0.27):(0.8-0.9):1.

[0017] By adopting the above technical scheme, the stability of the chemical structure of the prepared complex component A itself is ensured. When participating in the complexing of metal ions, the formed complex is more stable and effectively prevents the aggregation of metal ions. At the same time, the content of effective components in the nano-metal passivator is increased, thereby improving the passivation performance of the nano-metal passivator.

[0018] Preferably, in step (2), the mass ratio of acetic acid, water, phosphorus trichloride and p-aminophenylethanol is (1.8-2):1:(2-2.2):(0.9-1.1).

[0019] By adopting the above technical scheme, the complex dispersant has good complexing and dispersing properties. At the same time, terminal hydroxyl side chains are introduced into the complex dispersant, and their smaller steric hindrance and good flexibility are utilized to form hydrogen bonds between the terminal hydroxyl groups and the hydroxyl groups on the surface of the catalyst, thereby increasing the affinity between the effective components in the nano-metal passivator and the catalyst, thereby increasing its deposition rate on the catalyst, allowing the nano-metal passivator to give full play to its passivation ability and improving the catalyst activity.

[0020] Preferably, in step (2), the reflux reaction temperature is 110-130° C. and the time is 1.5-2 h.

[0021] By adopting the above technical scheme, the amount of terminal hydroxyl side chains introduced into the complex dispersant is increased, so that the complex dispersant is deposited more on the catalyst after reacting with metal ions, and its passivation performance is fully exerted. At the same time, the occurrence of side reactions is reduced, the stability of the complex dispersant is improved, and the active components in the nano-metal passivator have a good dispersion state, thereby improving the passivation ability of the nano-metal passivator.

[0022] Preferably, in step (3), the mass ratio of antimony trioxide, nitric acid, complexing dispersant and dimethylformamide is (5-6):(13.5-14.6):(4-6):1.

[0023] By adopting the above technical scheme, antimony trioxide is fully dissolved and dispersed in the solution in the form of antimony ions, which facilitates the full contact between the complexing dispersant and the antimony ions to form a complex with good dispersion, avoiding the agglomeration and precipitation of the antimony ions, and at the same time increasing the fluidity of the nano-metal passivator, so that the effective components of the passivator can fully contact with the catalyst and the polluted metals, thereby playing a good passivation role.

[0024] Preferably, in step (3) and step (4), the pH value adjusted by the alkaline solution is 6-7.

[0025] More preferably, the alkali solution is aqueous ammonia or ethylenediamine.

[0026] By adopting the above technical scheme, a good complexing environment is provided for the complexing dispersant, so that the complexing dispersant forms a stable complex with the metal ions, and at the same time has good dispersion stability, effectively inhibiting the agglomeration of metal ions, thereby increasing the content of effective components of the nano-metal passivator and improving the performance of the nano-metal passivator.

[0027] Preferably, in step (3), the temperature for uniform dispersion is 80-110° C. and the time is 1.5-2 h.

[0028] By adopting the above technical solution, the dispersion rate of the effective components in the passivator A is improved, so that they are uniformly and stably present in the passivator A in a relatively short period of time. At the same time, the re-agglomeration of the active components in the passivator A due to long-term dispersion is avoided, thereby enhancing the stability of the passivator A.

[0029] Preferably, in step (4), the mass ratio of lanthanum oxide, nitric acid, complexing dispersant and dimethylformamide is (2-2.5):(9-11.3):(3-4):1.

[0030] By adopting the above technical scheme, nitric acid can fully dissolve lanthanum oxide and completely release lanthanum ions, so that the lanthanum ions can fully contact with the complex dispersant to form a stable complex. At the same time, dimethylformamide makes the complex evenly dispersed, thereby enhancing the stability of the passivator. In the catalytic cracking reaction, it can effectively inhibit the poisoning of the pollutant metal to the catalyst and improve the activity of the catalyst.

[0031] Preferably, in step (4), the temperature for uniform dispersion is 100-120° C. and the time is 1-2 h.

[0032] By adopting the above technical solution, the thermal motion of dimethylformamide molecules is intensified, and they can be quickly and evenly dispersed in the system, so that the complex formed by the complex dispersant and the lanthanum ion is fully mixed with dimethylformamide, and the dimethylformamide is used to further improve the dispersion uniformity of the complex and improve the passivation performance of the nano metal passivator.

[0033] Preferably, in step (5), the mass ratio of passivator A to passivator B is (0.8-0.9):1.

[0034] By adopting the above technical solution, the agglomeration problem of nano-metal passivator can be avoided, ensuring that the passivator can play a stable and lasting role, effectively improving the activity of the catalyst, and providing a strong guarantee for the stable operation of catalytic cracking.

[0035] In summary, this application has the following beneficial effects:

[0036] 1. The phosphate group has a strong complexing effect on metal ions, and a complexing agent with dispersibility is prepared. Multiple phosphonic acid groups increase the number of coordination sites with metal ions, making the formed complex structure more stable and with greater steric hindrance, making it difficult for them to agglomerate close to each other, and thus enhancing dispersibility, reducing the concentration of the passivator and increasing the content of the effective ingredients of the passivator.

[0037] 2. The phosphoric acid group is connected to the benzene ring through a nitrogen atom, and the thermal stability of the entire molecule is enhanced. It is not easy to decompose and volatilize under high temperature conditions, which can ensure that the effective components in the passivator are more deposited on the catalyst surface, fully contact and react with the contaminated metal, thereby enhancing the passivation effect on the metal.

[0038] 3. During the preparation of the complex dispersant, p-aminophenylethanol is added to introduce long-chain terminal hydroxyl groups, increase the affinity between the complex dispersant and the catalyst, increase the deposition rate of the active components in the passivator on the catalyst, and improve the passivation ability of the passivator. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a schematic diagram showing the effect of the amount of nano-metal passivator added on the catalyst activity prepared in Example 1 of the present application.

[0040] Figure 2 It is a schematic diagram of the effect of the nano-metal passivator prepared in the examples and comparative examples of the present application on the yield.

[0041] Figure 3 It is a passivation performance diagram of the nano metal passivator prepared in the examples and comparative examples of the present application. DETAILED DESCRIPTION

[0042] The present application is further described in detail below with reference to the embodiments.

[0043] Unless otherwise specified, the raw materials used in the examples and comparative examples of the present application are all commercially available.

[0044] Example 1

[0045] The preparation method of the nano metal passivator of this embodiment comprises the following steps:

[0046] (1) 24 g of p-phenylenediamine and 80 g of a 37% formaldehyde aqueous solution were mixed evenly, and 100 g of phosphorus trichloride was added dropwise at a rate of 1.8 g / min. The reaction temperature was controlled below 40°C. After the addition of phosphorus trichloride was completed, the reaction was continued for 30 min, and then the temperature was raised to 110°C and the reaction was continued for 2.5 h to obtain a complexing agent a;

[0047] (2) 48 g of acetic acid and 30 g of water were mixed evenly, and 60 g of phosphorus trichloride was added dropwise at a rate of 1.5 g / min. The reaction temperature was controlled below 40°C. After the addition of phosphorus trichloride was completed, the reaction was continued for 15 min. Ammonia water was added to adjust the pH value to 7. 27 g of p-aminophenylethanol was added. The temperature was raised to 110°C, refluxed for 2 h, cooled to 50°C, 100 g of complexing agent a was added, and the reaction was continued for 30 min to obtain a complexing dispersant.

[0048] (3) Take 5g of antimony trioxide, add 13.5g of 33% nitric acid aqueous solution at a drop rate of 1g / min, the reaction temperature is 30°C, continue to react for 10min after the addition is completed, add 4g of complexing dispersant, add ammonia water to adjust the pH value to 6, the reaction temperature is 40°C, stir and react for 1.5h, add 1g of dimethylformamide, raise the temperature to 80°C, and react for 2h to obtain passivating agent A;

[0049] (4) Weigh 2 g of lanthanum oxide, add 9 g of 33% nitric acid aqueous solution at a drop rate of 0.9 g / min, the reaction temperature is 30°C, continue to react for 10 min after the addition is completed, add 3 g of complexing dispersant, add ammonia water to adjust the pH value to 7, the reaction temperature is 45°C, stir and react for 1.5 h, add 1 g of dimethylformamide, raise the temperature to 100°C, and react for 2 h to obtain passivating agent B;

[0050] (5) Mix 80 g of passivator A and 100 g of passivator B evenly to obtain a nano metal passivator.

[0051] Example 2

[0052] The preparation method of the nano metal passivator of this embodiment comprises the following steps:

[0053] (1) 27 g of p-phenylenediamine and 90 g of a 37% formaldehyde aqueous solution were mixed evenly, and 100 g of phosphorus trichloride was added dropwise at a rate of 2 g / min. The reaction temperature was controlled below 40°C. After the addition of phosphorus trichloride was completed, the reaction was continued for 30 min, and then the temperature was raised to 120°C and the reaction was continued for 2.5 h to obtain complexing agent a;

[0054] (2) 60 g of acetic acid and 30 g of water were mixed evenly, and 66 g of phosphorus trichloride was added dropwise at a rate of 1.7 g / min. The reaction temperature was controlled below 40°C. After the addition of phosphorus trichloride was completed, the reaction was continued for 15 min. Ammonia water was added to adjust the pH value to 7. 33 g of p-aminophenylethanol was added. The temperature was raised to 130°C, and the reaction was refluxed for 1.5 h. The temperature was lowered to 50°C, and 110 g of complexing agent a was added. The reaction was allowed to react for 40 min to obtain a complexing dispersant.

[0055] (3) Take 6g of antimony trioxide, add 14.6g of 33% nitric acid aqueous solution at a drop rate of 1.3g / min, the reaction temperature is 40°C, continue to react for 10min after the addition is completed, add 6g of complexing dispersant, add ethanolamine to adjust the pH value to 7, the reaction temperature is 40°C, stir and react for 2h, add 1g of dimethylformamide, raise the temperature to 110°C, and react for 1.5h to obtain passivating agent A;

[0056] (4) Weigh 2 g of lanthanum oxide, add 9 g of 33% nitric acid aqueous solution at a drop rate of 0.9 g / min, the reaction temperature is 30°C, continue to react for 10 min after the addition is completed, add 3 g of complexing dispersant, add ethanolamine to adjust the pH value to 6, the reaction temperature is 45°C, stir and react for 2 h, add 1 g of dimethylformamide, raise the temperature to 120°C, and react for 1 h to obtain passivating agent B;

[0057] (5) Mix 90 g of passivator A and 100 g of passivator B evenly to obtain a nano metal passivator.

[0058] Example 3

[0059] The preparation method of the nano metal passivator of this embodiment comprises the following steps:

[0060] (1) 25 g of p-phenylenediamine and 84 g of a 37% formaldehyde aqueous solution were mixed evenly, and 100 g of phosphorus trichloride was added dropwise at a rate of 1.9 g / min. The reaction temperature was controlled below 40°C. After the addition of phosphorus trichloride was completed, the reaction was continued for 30 min, and then the temperature was raised to 115°C and the reaction was continued for 2 h to obtain complexing agent a;

[0061] (2) 50 g of acetic acid and 30 g of water were mixed evenly, and 65 g of phosphorus trichloride was added dropwise at a rate of 1.5 g / min. The reaction temperature was controlled below 40°C. After the addition of phosphorus trichloride was completed, the reaction was continued for 15 min. Ammonia water was added to adjust the pH value to 7. 30 g of p-aminophenylethanol was added. The temperature was raised to 115°C, and the reaction was refluxed for 1.6 h. The temperature was lowered to 50°C, and 103 g of complexing agent a was added. The reaction was allowed to react for 30 min to obtain a complexing dispersant.

[0062] (3) Take 5.2g of antimony trioxide, add 14g of 33% nitric acid aqueous solution at a drop rate of 1g / min, the reaction temperature is 30°C, continue to react for 10min after the addition is completed, add 4.5g of complexing dispersant, add ammonia water to adjust the pH value to 6.5, the reaction temperature is 40°C, stir and react for 1.5h, add 1g of dimethylformamide, raise the temperature to 90°C, and react for 1.7h to obtain passivating agent A;

[0063] (4) Weigh 2.1 g of lanthanum oxide, add 10 g of 33% nitric acid aqueous solution at a drop rate of 0.9 g / min, the reaction temperature is 30°C, continue to react for 10 min after the addition is completed, add 3.2 g of complexing dispersant, add ammonia water to adjust the pH value to 6.5, the reaction temperature is 45°C, stir and react for 1.5 h, add 1 g of dimethylformamide, raise the temperature to 110°C, and react for 1.5 h to obtain passivating agent B;

[0064] (5) Mix 85 g of passivator A and 100 g of passivator B evenly to obtain a nano metal passivator.

[0065] Comparative Example 1

[0066] The preparation method of the nano metal passivator of this comparative example comprises the following steps:

[0067] (1) 24 g of ammonium chloride and 80 g of a 37% formaldehyde aqueous solution were mixed evenly, and 100 g of phosphorus trichloride was added dropwise at a dropping rate of 1.8 g / min. The reaction temperature was controlled below 40°C. After the addition of phosphorus trichloride was completed, the reaction was continued for 30 min, and then the temperature was raised to 110°C and the reaction was continued for 2.5 h to obtain complexing agent a;

[0068] (2) 48 g of acetic acid and 30 g of water were mixed evenly, and 60 g of phosphorus trichloride was added dropwise at a rate of 1.5 g / min. The reaction temperature was controlled below 40°C. After the addition of phosphorus trichloride was completed, the reaction was continued for 15 min. Ammonia water was added to adjust the pH value to 7. 27 g of p-aminophenylethanol was added. The temperature was raised to 110°C, refluxed for 2 h, cooled to 50°C, 100 g of complexing agent a was added, and the reaction was continued for 30 min to obtain a complexing dispersant.

[0069] (3) Take 5g of antimony trioxide, add 13.5g of 33% nitric acid aqueous solution at a drop rate of 1g / min, the reaction temperature is 30°C, continue to react for 10min after the addition is completed, add 4g of complexing dispersant, add ammonia water to adjust the pH value to 6, the reaction temperature is 40°C, stir and react for 1.5h, add 1g of dimethylformamide, raise the temperature to 80°C, and react for 2h to obtain passivating agent A;

[0070] (4) Weigh 2 g of lanthanum oxide, add 9 g of 33% nitric acid aqueous solution at a drop rate of 0.9 g / min, the reaction temperature is 30°C, continue to react for 10 min after the addition is completed, add 3 g of complexing dispersant, add ammonia water to adjust the pH value to 7, the reaction temperature is 45°C, stir and react for 1.5 h, add 1 g of dimethylformamide, raise the temperature to 100°C, and react for 2 h to obtain passivating agent B;

[0071] (5) Mix 80 g of passivator A and 100 g of passivator B evenly to obtain a nano metal passivator.

[0072] Comparative Example 2

[0073] The preparation method of the nano metal passivator of this comparative example comprises the following steps:

[0074] (1) 24 g of p-phenylenediamine and 80 g of a 37% formaldehyde aqueous solution were mixed evenly, and 100 g of phosphorus trichloride was added dropwise at a rate of 1.8 g / min. The reaction temperature was controlled below 40°C. After the addition of phosphorus trichloride was completed, the reaction was continued for 30 min, and then the temperature was raised to 110°C and the reaction was continued for 2.5 h to obtain a complexing agent a;

[0075] (2) 48 g of acetic acid and 30 g of water were mixed evenly, and 60 g of phosphorus trichloride was added dropwise at a rate of 1.5 g / min. The reaction temperature was controlled below 40°C. After the addition of phosphorus trichloride was completed, the reaction was continued for 15 min, the temperature was raised to 110°C, refluxed for 2 h, the temperature was lowered to 50°C, 100 g of complexing agent a was added, and the reaction was continued for 30 min to obtain a complexing dispersant;

[0076] (3) Take 5g of antimony trioxide, add 13.5g of 33% nitric acid aqueous solution at a drop rate of 1g / min, the reaction temperature is 30°C, continue to react for 10min after the addition is completed, add 4g of complexing dispersant, add ammonia water to adjust the pH value to 6, the reaction temperature is 40°C, stir and react for 1.5h, add 1g of dimethylformamide, raise the temperature to 80°C, and react for 2h to obtain passivating agent A;

[0077] (4) Weigh 2 g of lanthanum oxide, add 9 g of 33% nitric acid aqueous solution at a drop rate of 0.9 g / min, the reaction temperature is 30°C, continue to react for 10 min after the addition is completed, add 3 g of complexing dispersant, add ammonia water to adjust the pH value to 7, the reaction temperature is 45°C, stir and react for 1.5 h, add 1 g of dimethylformamide, raise the temperature to 100°C, and react for 2 h to obtain passivating agent B;

[0078] (5) Mix 80 g of passivator A and 100 g of passivator B evenly to obtain a nano metal passivator.

[0079] Performance testing

[0080] 1. Light oil micro-reaction experiment: refer to NB / SH / T0952-2017 for light oil micro-reaction experiment, experimental conditions: raw oil is 235-337℃ straight-run light diesel fraction, reaction pressure is 0.1MPa, reaction temperature is 460℃, oil feed volume is 1.56g, catalyst loading volume is 5g, catalyst-oil mass ratio is 3.2, post-reaction purge gas is nitrogen, purge gas flow rate is 30mL / min; Experimental method: the reactor and product receiver are thoroughly cleaned with acetone and blown dry, quartz sand is filled at about 20mm below the reactor, and then 5g catalyst is added to the reactor in a free-flowing manner, which should be ensured to be loaded into the middle section of the reactor, tap the reactor to ensure that the catalyst is well distributed, insert the reactor into the heating furnace, connect the nitrogen purge pipeline and the reactor feed line, the nitrogen purge gas flow rate is 30mL / min, the purge time is 30min, start the oil pump, calibrate the oil output rate, weigh the empty weight of the receiver, install it at the bottom of the reactor and place it in an ice water bath. Close the nitrogen valve, and when the temperature rises to 460°C, start feeding, the feeding time is 75s, and the feeding amount is 1.56g. After the feeding is completed, open the nitrogen valve, purge the reactor, and maintain the air flow at 30mL / min for 15min to allow the product to completely enter the liquid receiver. Finally, remove the product receiver from the reactor, quickly seal it, wipe it dry, and weigh it. The composition analysis of the product is determined by ASTM D7964 method, and the micro-activity index is calculated based on the data recorded by the HP integrator.

[0081] 2. Preparation of catalyst: 20 g of RICC-3 catalyst was calcined in a muffle furnace at 350 ° C for 4 hours. The catalyst was impregnated with vanadium cyclopentaneate and nickel cyclopentaneate dissolved in petroleum ether by the Mitchell artificial impregnation method to increase the contents of nickel and vanadium on the catalyst to 6000 mg / L and 3000 mg / L, respectively. The catalyst was calcined at 550 ° C for 3 hours to remove residual carbon deposits. The catalyst was hydrothermally treated at 700 ° C and 100% steam for 4 hours to prepare a blank catalyst. 20 g of the blank catalyst was immersed in a passivator solution consisting of a nano-metal passivator and 30 g of water for 30 min. After the immersion, the catalyst was taken out and hydrothermally treated at 750 ° C and 100% steam for 4 hours to prepare a passivated catalyst.

[0082] In the preparation process of the passivated catalyst, the amount of nanometal passivator added is controlled to observe the effect of the amount of nanometal passivator added on the catalyst activity. Figure 1 shown.

[0083] When the amount of the nano-metal passivator added was 0.4 g, the effects of the blank catalyst, Examples 1-3, Comparative Example 1 and Comparative Example 2 on the catalytic cracking reaction were observed. Figure 2 and Figure 3 shown.

[0084] Analyze Examples 1-3, Comparative Example 1, Comparative Example 2 and combine Figure 1-3 It can be seen that the nano-metal passivator prepared in the present application has a good effect in improving the conversion rate of catalytic cracking reaction and the yield of gasoline and diesel, and also effectively reduces the content of hydrogen and coke, thereby improving the activity of the catalyst.

[0085] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A method for preparing a nano metal passivator, characterized in that: The steps include: (1) Evenly mix p-phenylenediamine and formaldehyde aqueous solution, then add phosphorus trichloride and heat to react to obtain complex component a; (2) Mix acetic acid and water evenly, add phosphorus trichloride, stir to react, add ammonia water to adjust the pH, then add p-aminophenylethanol, reflux to react, after the reaction is completed, cool, add complexing component a and mix evenly to obtain a complexing dispersant; (3) Mix antimony trioxide and nitric acid, add a complexing dispersant, adjust with alkali solution, stir to react, add dimethylformamide, and evenly disperse to obtain a passivating agent A; (4) Mix lanthanum oxide and nitric acid, add a complexing dispersant, adjust with alkali solution, stir to react, add dimethylformamide, and evenly disperse to obtain a passivating agent B; (5) Passivator A and passivator B are mixed to obtain a nano metal passivator.

2. The method for preparing a nano metal passivator according to claim 1, characterized in that: In the step (1), the mass ratio of p-phenylenediamine, formaldehyde aqueous solution and phosphorus trichloride is (0.24-0.27):(0.8-0.9):

1.

3. The method for preparing a nano metal passivator according to claim 1, characterized in that: In the step (2), the mass ratio of acetic acid, water, phosphorus trichloride and p-aminophenylethanol is (1.8-2):1:(2-2.2):(0.9-1.1).

4. The method for preparing a nano metal passivator according to claim 1, characterized in that: In the step (2), the reflux reaction temperature is 110-130° C. and the time is 1.5-2 h.

5. The method for preparing a nano metal passivator according to claim 1, characterized in that: In the step (3), the mass ratio of antimony trioxide, nitric acid, complexing dispersant and dimethylformamide is (5-6):(13.5-14.6):(4-6):

1.

6. The method for preparing a nano metal passivator according to claim 1, characterized in that: In the steps (3) and (4), the pH of the alkali solution is adjusted to 6-7.

7. The method for preparing a nano metal passivator according to claim 1, characterized in that: In the step (3), the temperature for uniform dispersion is 80-110° C. and the time is 1.5-2 h.

8. The method for preparing a nano metal passivator according to claim 1, characterized in that: In the step (4), the mass ratio of lanthanum oxide, nitric acid, complexing dispersant and dimethylformamide is (2-2.5):(9-11.3):(3-4):

1.

9. The method for preparing a nano metal passivator according to claim 1, characterized in that: In the step (4), the temperature for uniform dispersion is 100-120°C and the time is 1-2h.

10. The method for preparing a nano metal passivator according to claim 1, characterized in that: In the step (5), the mass ratio of passivator A to passivator B is (0.8-0.9):1.

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