A bismuth-based metal passivating agent and its preparation method
By preparing heteronuclear metal-organic clusters, the problem of bismuth atoms being aggregated and unevenly dispersed at high temperatures was solved by using organosilicon alkyl groups to anchor and auxiliary metals to isolate bismuth atoms, thus improving the stability and passivation effect of the passivating agent.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- JIANGSU CHUANGXIN PETROCHEM
- Filing Date
- 2026-03-23
- Publication Date
- 2026-05-26
Smart Images
Figure CN121896025B_ABST
Abstract
Description
Technical Field
[0001] This application belongs to the field of metal passivating agent technology, and in particular relates to a bismuth-based metal passivating agent and its preparation method. Background Technology
[0002] Fluid catalytic cracking (FCC) is a core process in modern oil refining, converting heavy hydrocarbons into products such as gasoline and olefins using catalysts, replacing the earlier thermal cracking process. However, as crude oil becomes increasingly heavy and of lower quality, the content of polluting metals such as nickel, vanadium, and iron in feedstocks continues to rise. These polluting metals deposit on the catalyst surface in the FCC reaction-regeneration system, causing catalyst poisoning or even deactivation.
[0003] To effectively mitigate the poisoning effect of contaminating metals on catalysts, trace amounts of metal passivators are typically added to the feedstock. The active components of the passivator can interact with the contaminating metals, thereby inhibiting their activity. Bismuth-based metal passivators have attracted considerable attention due to their ability to form stable compounds with contaminating metals such as nickel and vanadium, exhibiting excellent passivation effects.
[0004] To improve compatibility with feedstock oil, bismuth active components are usually combined with organic ligands to form complexes. However, in the high-temperature environment (510-550℃) of FCC riser reactors, organic ligands may undergo uncontrollable thermal decomposition prematurely, losing their stabilizing effect. Bismuth active components are prone to agglomeration or uneven dispersion, reducing effective contact with contaminated metals and ultimately lowering passivation efficiency.
[0005] To address the issue of high-temperature instability of organic ligands in bismuth-based metal passivators, a common approach is to develop highly stable organic ligands. For example, patent application CN120574600A discloses a highly efficient and environmentally friendly petroleum passivator, its preparation method, and its application. This involves reacting bismuth nitrate with tetrakis(4-carboxyphenyl)porphyrin and benzoic acid to prepare carboxyphenylporphyrin bismuth-MOF materials. The organic ligand carboxyphenylporphyrin can provide multiple coordination sites for bismuth ions, forming stable coordination bonds, thus exhibiting good thermal stability and maintaining structural and performance stability under certain high-temperature conditions. However, it may still decompose under the high-temperature environment of an FCC reactor, causing the bismuth active components to aggregate or disperse unevenly, thereby reducing the passivation effect. Furthermore, at high temperatures, partial decomposition may produce more complex carbon deposits, leading to new problems. Summary of the Invention
[0006] To address the aforementioned issues, this application provides a bismuth-based metal passivating agent and its preparation method.
[0007] This application first provides a method for preparing a bismuth-based metal passivating agent, comprising the following steps:
[0008] S1: Dissolve bismuth salt and auxiliary metal salt in dilute nitric acid to obtain a mixed salt solution;
[0009] S2: Dissolve organic carboxylic acids in an organic solvent, add the above mixed salt solution under nitrogen protection, and react to obtain heteronuclear metal-organic clusters;
[0010] S3: The above heteronuclear metal-organic clusters are reacted with silane coupling agents under the action of a catalyst.
[0011] Furthermore, in step S1, the bismuth salt is one or more of bismuth nitrate pentahydrate, bismuth nitrate, bismuth subnitrate, and bismuth chloride.
[0012] Furthermore, in step S1, the auxiliary metal salt is one or more of zinc salt, magnesium salt, calcium salt, lanthanum salt, and cerium salt.
[0013] Furthermore, in step S1, the molar ratio of bismuth salt to auxiliary metal salt is 1:(0.1-0.3).
[0014] Furthermore, in step S2, the organic carboxylic acid is a C6-C18 carboxylic acid.
[0015] Furthermore, the organic carboxylic acid is one or more of isononanoic acid, 2-ethylhexanoic acid, and neodecanoic acid.
[0016] Furthermore, in step S2, the molar ratio of the sum of the moles of bismuth and auxiliary metals in the mixed salt to the molar ratio of the organic carboxylic acid is 1:(2-5).
[0017] Furthermore, in step S3, the catalyst is dibutyltin dilaurate or tetrabutyl titanate;
[0018] And / or, the silane coupling agent is one or more of 3-mercaptopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-isocyanopropyltriethoxysilane, and 3-isocyanopropyltrimethoxysilane.
[0019] Furthermore, in step S3, the mass ratio of the heteronuclear metal-organic cluster compound to the silane coupling agent is 1:(0.5-2).
[0020] This application also provides a bismuth-based metal passivating agent, which is prepared by the above-described method.
[0021] Compared with the prior art, this application has the following beneficial effects:
[0022] 1. This application introduces organosiloxane alkyl groups to provide anchoring sites for the passivator, thereby enabling the passivator to be positioned on the surface of the FCC catalyst, reducing the loss or ineffective dispersion of bismuth active components, and thus improving the passivation effect of bismuth-based metal passivators.
[0023] 2. This application uses long-chain alkyl organic carboxylic acids as ligands to improve compatibility with feedstock oil, and bismuth and auxiliary metals as active components. Under high temperature conditions, as the organic carboxylic acids decompose, bismuth and auxiliary metals interact. The auxiliary metals can effectively isolate bismuth atoms and prevent bismuth atom aggregation, so that the bismuth active components are highly dispersed on the catalyst surface. At the same time, the auxiliary metals and bismuth active components work together to react with contaminating metals and improve the passivation effect on contaminating metals.
[0024] 3. The introduction of rare earth elements in this application can effectively reduce the penetration of contaminating metals into the catalyst and further improve the passivation effect on contaminating metals. Attached Figure Description
[0025] Figure 1 SEM images of FCC catalysts treated with bismuth-based metal passivators as described in Example 1 and Control Group 1 of this application.
[0026] Figure 2 The infrared spectrum of the bismuth-zinc organic cluster obtained in step S2 of Example 1 is shown.
[0027] Figure 3 The infrared spectrum of the bismuth-based metal passivator in Example 1 is shown. Detailed Implementation
[0028] To make the inventive objectives, technical solutions, and beneficial technical effects of this application clearer, the following detailed description is provided in conjunction with embodiments, clearly and completely describing the technical solutions in the embodiments of this application. Obviously, the described embodiments are merely some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.
[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.
[0030] When using “including,” “having,” and “contains” as described herein, the intention is to cover non-exclusive inclusion, unless an explicit qualifying term such as “only,” “consisting of,” etc., is used, in which case another component may be added.
[0031] The terms "preferred," "more preferably," "better," and "even better" used in this application refer to embodiments of this application that provide certain beneficial effects under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of this application. That is, in this application, "preferred," "more preferably," "better," and "even better" are merely descriptions of implementations or embodiments with better effects, but do not constitute a limitation on the scope of protection of this application.
[0032] In this application, terms such as "further," "even more," and "particularly" are used for descriptive purposes and indicate differences in content, but should not be construed as limiting the scope of protection of this application.
[0033] In this application, "at least one" means one or more, such as one, two, or more. "Multiple" or "several" means at least two, such as two, three, etc., and "multi-layered" means at least two layers, such as two layers, three layers, etc., unless otherwise explicitly specified. In the description of this application, "several" means at least one, such as one, two, etc., unless otherwise explicitly specified.
[0034] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.
[0035] Unless otherwise specified, all steps in this application may be performed sequentially or randomly. For example, the method comprising steps (a) and (b) indicates that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order; for example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc. Unless otherwise stated, singular terms may include plural forms and should not be construed as having a quantity of one.
[0036] In this application, "above" or "below" includes the stated number. For example, "below 1" includes 1.
[0037] In this application, room temperature refers to 0-40°C, including but not limited to 10-40°C, or further to 20-30°C.
[0038] Based on extensive experimental research, this application provides a method for preparing a bismuth-based metal passivating agent, comprising the following steps:
[0039] S1: Dissolve bismuth salt and auxiliary metal salt in dilute nitric acid to obtain a mixed salt solution;
[0040] S2: Dissolve organic carboxylic acids in an organic solvent, add the above mixed salt solution under nitrogen protection, and react to obtain heteronuclear metal-organic clusters;
[0041] S3: The above heteronuclear metal-organic clusters are reacted with silane coupling agents under the action of a catalyst.
[0042] In some embodiments of this application, at lower temperatures, the silanol groups generated by the siloxane groups in the bismuth-based metal passivator condense with the hydroxyl groups on the catalyst surface, anchoring the passivator molecules to the catalyst surface and preventing the loss or ineffective dispersion of the bismuth active component. After anchoring, as the temperature continues to rise, the organic carboxylic acid ligands decompose. At this point, the presence of the auxiliary metal can effectively isolate bismuth atoms, prevent bismuth atom aggregation, and effectively passivate contaminated metals. When passivating nickel, the bismuth and auxiliary metal active components on the catalyst surface come into contact with nickel, forming complex solid solutions or mixed oxides, reducing the dehydrogenation activity of nickel. When passivating vanadium, bismuth and auxiliary metal active components can react together with the migrating vanadium pentoxide to form more stable composite vanadates, thereby partially preventing vanadium from penetrating into the catalyst interior.
[0043] In some embodiments of this application, in step S1, the bismuth salt is one or more of bismuth pentahydrate, bismuth nitrate, bismuth subnitrate, and bismuth chloride, and the bismuth salt provides the main metal active component for the bismuth-based metal passivator.
[0044] In some embodiments of this application, in step S1, the auxiliary metal salt is one or more of zinc salt, magnesium salt, calcium salt, lanthanum salt, and cerium salt, which improves the dispersibility of the bismuth active component and synergistically enhances the passivation effect on contaminated metals with the bismuth active component.
[0045] In some embodiments of this application, in step S1, the molar ratio of bismuth salt to auxiliary metal salt is 1:(0.1-0.3), for example, it can be 1:0.1, 1:0.12, 1:0.15, 1:0.18, 1:0.2, 1:0.22, 1:0.25, 1:0.28, or 1:0.3.
[0046] In some embodiments of this application, in step S2, the organic carboxylic acid is a C6-C18 carboxylic acid, for example, it can be a C6-C18 straight-chain or branched organic carboxylic acid.
[0047] In some embodiments of this application, in step S1, the organic carboxylic acid is one or more of isononanoic acid, 2-ethylhexanoic acid, and neodecanoic acid.
[0048] In some specific embodiments of this application, in step S2, the molar ratio of the sum of the moles of bismuth and auxiliary metals in the mixed salt to the molar ratio of the organic carboxylic acid is 1:(2-5), for example, it can be 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, or 1:5.
[0049] In some specific embodiments of this application, in step S3, the catalyst is dibutyltin dilaurate or tetrabutyl titanate, and the amount used is 0.1%-1% of the total amount of reactants.
[0050] In some specific embodiments of this application, in step S3, the silane coupling agent is one or more of 3-mercaptopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-isocyanate-propyltriethoxysilane, and 3-isocyanate-propyltrimethoxysilane.
[0051] In some specific embodiments of this application, in step S3, the mass ratio of the heteronuclear metal-organic cluster compound to the silane coupling agent is 1:(0.5-2), for example, it can be 1:0.5, 1:0.8, 1:1, 1:1.2, 1:1.5, 1:1.8, or 1:2.
[0052] In addition, this application also provides a bismuth-based metal passivating agent, which is prepared by the above-described method.
[0053] The present application will be further illustrated by the following examples, but these examples do not limit the scope of the present application.
[0054] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in this application, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. All reagents or instruments whose manufacturers are not specified are conventional products that can be purchased commercially. In addition to the specific methods, equipment, and materials used in the embodiments, based on the knowledge of the prior art possessed by one of ordinary skill in the art and the description in this application, any prior art methods, equipment, and materials similar to or equivalent to those described, used, or made by the methods, equipment, and materials in the embodiments of this application may be used to implement this application.
[0055] Example 1
[0056] The preparation method of the bismuth-based metal passivator in this embodiment includes the following steps:
[0057] S1: Weigh 28.7g of bismuth subnitrate, 100mL of 0.2mol / L zinc nitrate solution and 100mL of 0.1mol / L nitric acid solution, stir to dissolve, and prepare bismuth zinc salt solution;
[0058] S2: Add 47.5 g of isononanoic acid and 200 mL of toluene to a four-necked flask equipped with a mechanical stirrer, a constant-pressure dropping funnel, a thermometer, and a nitrogen inlet tube. Purge with nitrogen and stir to raise the temperature to 80°C. While stirring, slowly add the above bismuth-zinc salt solution dropwise, controlling the dropping rate. The addition is completed in about 1 hour. After the addition is complete, slowly add a 25% ammonia solution through the constant-pressure dropping funnel to adjust the pH to 7. Raise the temperature to 135°C and dehydrate by azeotropic reflux for 6 hours. Then cool to 60°C and filter the mixture. Wash the filter cake with n-hexane and then dry it under vacuum to obtain the bismuth-zinc organic cluster.
[0059] S3: Weigh 15g of the above bismuth-zinc organic cluster compound, 200mL of toluene, and 0.1g of tetrabutyl titanate, and place them in a four-necked flask equipped with a mechanical stirrer, a constant pressure dropping funnel, a thermometer, and a nitrogen inlet tube. Under nitrogen protection, stir evenly, raise the temperature to 55℃, and slowly add 15g of 3-isocyanatopropyltrimethoxysilane dropwise, controlling the dropwise addition time to about 1.5h. After the dropwise addition is complete, raise the temperature to 115℃ and reflux for 7h. After the reaction is complete, filter while hot, and distill the filtrate under reduced pressure at 80℃ using a rotary evaporator.
[0060] Example 2
[0061] The preparation method of the bismuth-based metal passivator in this embodiment includes the following steps:
[0062] S1: Weigh 28.7g of bismuth subnitrate, 50mL of 0.2mol / L zinc nitrate solution, 4.3g of cerium nitrate hexahydrate, and 100mL of 0.1mol / L nitric acid solution, stir to dissolve, and prepare a bismuth zinc cerium salt solution;
[0063] S2: Add 47.5 g of isononanoic acid and 200 mL of toluene to a four-necked flask equipped with a mechanical stirrer, a constant-pressure dropping funnel, a thermometer, and a nitrogen inlet tube. Purge with nitrogen and stir to raise the temperature to 80°C. While stirring, slowly add the above bismuth-zinc-cerium salt solution, controlling the dropping rate. The addition is completed in about 1 hour. After the addition is complete, slowly add a 25% ammonia solution through the constant-pressure dropping funnel to adjust the pH to 7. Raise the temperature to 135°C and dehydrate by azeotropic reflux for 6 hours. Then cool to 60°C and filter the mixture. Wash the filter cake with n-hexane and then vacuum dry to obtain the bismuth-zinc-cerium organic cluster.
[0064] S3: Weigh 15g of the above bismuth zinc cerium organic cluster compound, 200mL of toluene, and 0.1g of tetrabutyl titanate, and place them in a four-necked flask equipped with a mechanical stirrer, a constant pressure dropping funnel, a thermometer, and a nitrogen inlet tube. Under nitrogen protection, stir evenly, raise the temperature to 80℃, and slowly add 18g of 3-isocyanate-propyltriethoxysilane dropwise, controlling the dropwise addition time to about 1.5h. After the dropwise addition is complete, raise the temperature to 110℃ and reflux for 5h. After the reaction is complete, filter while hot, and distill the filtrate under reduced pressure at 80℃ using a rotary evaporator.
[0065] Control group 1
[0066] The preparation method of the bismuth-based metal passivator in this control group includes the following steps:
[0067] S1: Weigh 28.7g of bismuth subnitrate and 100mL of 0.1mol / L hydrochloric acid solution, stir to dissolve, and prepare a bismuth salt solution;
[0068] S2: Add 39.5g of isononanoic acid and 200mL of toluene to a flask, mix well, heat to 80℃, and slowly add the above bismuth salt solution dropwise while stirring, controlling the dropping rate. The addition should be completed in about 1 hour. After the addition is complete, slowly add a 25% ammonia solution through a constant pressure dropping funnel to adjust the pH to 7. Heat to 135℃ and dehydrate by azeotropic reflux for 6 hours. Then cool to 60℃, filter the mixture, wash the filter cake with n-hexane, and then vacuum dry it.
[0069] Control group 2
[0070] The preparation method of the bismuth-based metal passivator in this control group includes the following steps:
[0071] S1: Weigh 28.7g of bismuth subnitrate, 100mL of 0.2mol / L zinc nitrate solution and 100mL of 0.1mol / L nitric acid solution, stir to dissolve, and prepare bismuth zinc salt solution;
[0072] S2: Add 47.5g of isononanoic acid and 200mL of toluene to a flask, mix well, heat to 80℃, and slowly add the above bismuth salt solution dropwise while stirring, controlling the dropping rate. The addition should be completed in about 1 hour. After the addition is complete, slowly add a 25% ammonia solution through a constant pressure dropping funnel to adjust the pH to 7. Heat to 135℃ and dehydrate by azeotropic reflux for 6 hours. Then cool to 60℃, filter the mixture, wash the filter cake with n-hexane, and then vacuum dry it.
[0073] Performance testing
[0074] 1. Light oil micro-reaction test
[0075] ①The experimental feedstock was atmospheric residue oil containing nickel naphthenate and vanadium naphthenate, with a total nickel and vanadium content of 80 ppm.
[0076] ②Reaction apparatus and experimental conditions: A micro fixed-bed reactor was used, the reaction temperature was 520±2℃, the agent-to-oil ratio was 5, and the weight hourly space velocity was 12h. -1 ;
[0077] ③ Catalyst pretreatment: Fresh FCC catalysts are pre-aged at 700℃ and 100% steam for 4 hours and then subjected to hydrothermal treatment;
[0078] ④ Experimental Design: Before the feed oil entered the reactor, bismuth-based metal passivating agents prepared in Examples 1-2 and Control Groups 1-2 were added to make the bismuth content in the feed oil about 30 ppm. A blank group was set up, that is, no bismuth-based metal passivating agent was added to the feed oil. Each group of experiments was run for 6 hours, and the product distribution was analyzed by online chromatography. The results are shown in Table 1.
[0079] Table 1: Results of micro-reaction test of light oil
[0080]
[0081] As can be seen from Table 1, compared with the blank group, the addition of bismuth-based metal passivator can reduce the yield of dry gas and coke and increase the yield of gasoline. Moreover, the bismuth-based passivator of Examples 1-2 is better than the bismuth-based metal passivator of Control Group 1 in terms of inhibiting nickel dehydrogenation, reducing coke production and increasing gasoline yield. This may be because the bismuth active components in Control Groups 1-2 agglomerate, are unevenly dispersed or have undergone ineffective dispersion, thereby reducing the passivation effect.
[0082] 2. Scanning electron microscopy observation
[0083] Equal amounts of the bismuth-based metal passivating agent prepared in Example 1 and Control Group 1 were added to equal amounts of hydrotreated tail oil and FCC catalyst, mixed thoroughly, and placed in a programmed temperature muffle furnace. The mixture was first treated at 300°C under a nitrogen atmosphere for 30 min, and then treated at 520°C in a 10% water vapor / nitrogen mixture for 2 h. The treated samples were observed using a scanning electron microscope. Figure 1 As shown.
[0084] from Figure 1 It can be seen that the active components formed by the bismuth-based metal passivator in control group 1 are less distributed on the surface of the FCC catalyst, and some agglomerate, resulting in uneven dispersion. In contrast, the active components formed by the bismuth-based metal passivator in Example 1 are more dispersed on the surface of the FCC catalyst, and the dispersion is better. This may be because zinc salt and silane coupling agent were added during the preparation of the bismuth-based metal passivator in Example 1, which not only effectively prevented the agglomeration of the bismuth active components, but also made more bismuth active components dispersed on the surface of the FCC catalyst.
[0085] 3. Infrared spectroscopy analysis
[0086] The bismuth-zinc organic cluster obtained in step S2 of Example 1 and the bismuth-based metal passivator obtained in step S3 of Example 1 were subjected to infrared spectroscopy analysis. The spectra are shown in the figure. Figure 2 and Figure 3 .
[0087] exist Figure 2 3627cm -1 The nearby absorption peak belongs to the free / terminal hydroxyl group and is located at 2920 cm⁻¹. -1 and 2850cm -1 The absorption peak at 1400-1600 cm⁻¹ is the absorption peak of the methyl / methylene group. -1 The strong absorption peak at 610 cm⁻¹ belongs to the symmetric / asymmetric stretching vibration of the carboxyl group. -1 The nearby characteristic peaks belong to the absorption peaks of Bi-O / Zn-O. From Figure 2 As can be seen from the reaction in step S2, the hydroxyl groups produced are not completely consumed and can participate in the reaction in step S2.
[0088] exist Figure 3 In the middle, it was originally located at 3627cm -1 The disappearance of the absorption peak of the free / terminal hydroxyl group at 1730 cm⁻¹ indicates that the hydroxyl group was consumed in step S2 due to its participation in the reaction. -1 A new, stronger absorption peak appeared nearby, at 2270 cm⁻¹, which is attributed to the stretching vibration of the carbonyl group in the carbamate bond. -1 The absence of absorption peaks for isocyanate groups nearby indicates that the isocyanate groups reacted with the hydroxyl groups.
[0089] Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.
Claims
1. A method for preparing a bismuth-based metal passivating agent, characterized in that: Includes the following steps: S1: Dissolve bismuth salt and auxiliary metal salt in dilute nitric acid to obtain a mixed salt solution; the auxiliary metal salt is one or more of zinc salt, magnesium salt, calcium salt, lanthanum salt, and cerium salt; S2: Dissolve an organic carboxylic acid in an organic solvent, add the above mixed salt solution under nitrogen protection, and react to obtain a heteronuclear metal-organic cluster compound; the organic carboxylic acid is a C6-C18 carboxylic acid; S3: The above heteronuclear metal-organic cluster compound is reacted with a silane coupling agent under the action of a catalyst; the catalyst is dibutyltin dilaurate or tetrabutyl titanate; the silane coupling agent is one or more of 3-mercaptopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-isocyanopropyltriethoxysilane, and 3-isocyanopropyltrimethoxysilane.
2. The method for preparing a bismuth-based metal passivating agent according to claim 1, characterized in that: In step S1, the bismuth salt is one or more of bismuth pentahydrate, bismuth nitrate, bismuth subnitrate, and bismuth chloride.
3. The method for preparing a bismuth-based metal passivating agent according to claim 1, characterized in that: In step S1, the molar ratio of bismuth salt to auxiliary metal salt is 1:(0.1-0.3).
4. The method for preparing a bismuth-based metal passivating agent according to claim 1, characterized in that: In step S2, the organic carboxylic acid is one or more of isononanoic acid, 2-ethylhexanoic acid, and neodecanoic acid.
5. The method for preparing a bismuth-based metal passivating agent according to claim 1, characterized in that: In step S2, the molar ratio of the sum of the moles of bismuth and auxiliary metals in the mixed salt to that of the organic carboxylic acid is 1:(2-5).
6. The method for preparing a bismuth-based metal passivating agent according to claim 1, characterized in that: In step S3, the mass ratio of the heteronuclear metal-organic cluster compound to the silane coupling agent is 1:(0.5-2).
7. A bismuth-based metal passivating agent, characterized in that: It is prepared by any one of the preparation methods described in claims 1-6.