Heteroatom-enhanced molybdenum-based flame-retardant smoke suppressant, and preparation method and application thereof

Abstract

The application discloses a kind of heteroatom enhanced molybdenum series flame-retardant smoke suppressant and its preparation method and application, it is related to flame-retardant smoke suppressant technical field.Heteroatom enhanced molybdenum series flame-retardant smoke suppressant includes the carbon carrier supported heteroatom modified molybdenum carbide material.Preparation method includes preparation precursor, realizes the uniform dispersion of molybdate and the salt class containing heteroatom in the surface and hole of solid-phase carbon source carrier using equal-volume impregnation method, and is obtained by high-temperature calcination, carbon carrier supported heteroatom modified molybdenum carbide material, on the one hand, the Lewis acidity of molybdenum carbide is enhanced by heteroatom modification, on the other hand, the dispersion uniformity of molybdenum carbide on carrier is improved by the form of loading, and the utilization rate and flame-retardant smoke suppression effect of molybdenum carbide in fireproof coating are improved.The application is promoted by Lewis acid catalysis to polymer system to form carbon, increases residual carbon amount, forms the carbon layer of more compact and uniform structure, reduces the amount of smoke, and significantly improves fireproof and heat insulation performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of flame-retardant and smoke-suppressing agents, and particularly relates to a heteroatom-enhanced molybdenum series flame-retardant and smoke-suppressing agent and a preparation method and application thereof. BACKGROUND

[0002] Steel structure has the advantages of high strength, light weight, good seismic resistance, high industrialization degree of production and installation, short construction period and the like, and is increasingly applied in the fields of construction, transportation, energy and the like. Although the steel structure belongs to non-combustible material, the fire resistance is poor. The bearing capacity and balance stability of the steel structure greatly decrease with the increase of temperature. When the temperature exceeds 400 DEG C, the yield strength of the steel structure decreases to half of the strength at room temperature. When the temperature exceeds 600 DEG C, the steel structure basically loses strength and stiffness, at this moment, the steel structure will completely lose the bearing capacity and seriously deform, and cannot continue to work. There are various fireproof methods for the steel structure, among which, the spraying of fireproof paint becomes the most ideal, most reliable and most practical fireproof protection method due to the simple, convenient, light weight and good fireproof effect.

[0003] Smoke suppressants are compounds that reduce the amount of smoke produced by a combustible material during combustion through special chemical and physical effects. According to the mechanism of action of smoke suppressants, they can be divided into physical type smoke suppressants and chemical type smoke suppressants. Physical type smoke suppressants are inexpensive and easy to use, not only can they play a role in flame retardation and smoke suppression, but also have a certain filling effect, but physical type smoke suppressants need to be added in large quantities to achieve good flame retardation and smoke suppression effect; and most physical type smoke suppressants have poor compatibility with high polymer materials, resulting in a significant reduction in the mechanical properties of the added materials; therefore, the use of physical type smoke suppressants is greatly limited. Chemical type smoke suppressants mainly achieve the purpose of smoke suppression by chemically reacting with the degradation products of polymers during polymer combustion, and can be divided into Lewis acid mechanism, reduction coupling mechanism according to the mechanism of action; and can be divided into gas phase smoke suppression and condensed phase smoke suppression according to the action mode. Chemical type smoke suppressants are relatively expensive, but a small amount of addition can achieve significant results, and moderate use has little effect on the mechanical properties of the material, and has become a hot spot for flame retardant and smoke suppressant for fire retardant coatings. At present, chemical type flame retardant and smoke suppressant mainly includes ferrocene-based compounds and iron-based smoke suppressant of iron oxide series, copper-based smoke suppressant represented by cuprous oxide and molybdenum-based smoke suppressant represented by molybdenum oxide and molybdate. Among them, molybdenum-based smoke suppressant is the best flame retardant and smoke suppressant that people have found so far, which can be used for various high polymers, can achieve the purpose of reducing smoke production while not compromising the flame retardant properties of the material, and therefore has attracted widespread attention, the main categories are melamine octamolybdate, molybdenum sulfide, molybdenum trioxide and various molybdate salts. Studies have shown that the addition of molybdenum-based smoke suppressant can change the decomposition mode of polyvinyl chloride during the degradation process, reducing the formation of cis-polyene, which is prone to continue to cyclize to form aromatic ring structure, and finally condense into graphitized carbon particles, i.e. black soot particles; while trans-polyene crosslinks, and finally generates solid coke instead of soot. Molybdenum-based smoke suppressant makes polyvinyl chloride crosslink as much as possible during the degradation process, rather than evolving into benzene-based polymers, thereby suppressing the smoke and flame retardation during the combustion process of polyvinyl chloride. Therefore, it is generally believed that the smoke suppression of molybdenum-based compounds is mainly through the Lewis acid mechanism to catalyze the formation of carbon layer in the early stage of combustion in the solid phase, improve the carbonization rate of the fire retardant coating, make the carbon layer after burning more dense, and the bubble structure more uniform, so that the fire retardant coating has better flame retardant effect, and can significantly reduce the smoke production of the fire retardant coating.

[0004] Molybdenum-based compounds exhibit excellent flame retardant and smoke suppression effect in various types of polymers, but generally have the problems of low efficiency, high price and high cost when used alone. Therefore, it is of great significance to develop new high-efficiency molybdenum-based flame retardant and smoke suppressant and improve the efficiency of molybdenum-based flame retardant and smoke suppressant to promote the application of molybdenum-based compounds in fire retardant coatings. SUMMARY

[0005] To solve the above technical problems, the application discloses a heteroatom enhanced molybdenum series flame-retardant smoke suppressant, a preparation method and application thereof.

[0006] To achieve the above object, the application adopts the following technical scheme:

[0007] The first aspect of the application provides a molybdenum carbide material.

[0008] In an optional embodiment, the molybdenum carbide material is modified by heteroatoms supported by a carbon carrier.

[0009] Optionally, the heteroatoms include one or more of nitrogen, phosphorus and sulfur.

[0010] The second aspect of the application provides a heteroatom enhanced molybdenum series flame-retardant smoke suppressant.

[0011] In an optional embodiment, the heteroatom enhanced molybdenum series flame-retardant smoke suppressant includes the molybdenum carbide material provided in the first aspect of the application.

[0012] In the heteroatom enhanced molybdenum series flame-retardant smoke suppressant, the electronic structure and chemical properties of the molybdenum carbide are changed by modification of nitrogen, phosphorus and sulfur, so as to enhance the Lewis acidity of the molybdenum carbide. The Lewis acid active sites of the molybdenum carbide catalyze the formation of a carbon layer in the early stage of combustion of the fireproof coating, improve the carbonization rate of the fireproof coating, increase the residual carbon amount of the fireproof coating after combustion, make the carbon layer after burning more dense, and the vesicular structure more uniform, so as to make the fireproof coating have better flame-retardant effect, and significantly reduce the smoke generation of the fireproof coating.

[0013] The third aspect of the application provides a preparation method of the heteroatom enhanced molybdenum series flame-retardant smoke suppressant.

[0014] The application realizes uniform dispersion of molybdate and salt containing heteroatoms on the surface and holes of solid-phase carbon source carrier by using equal volume impregnation method, and obtains heteroatom modified carbonized molybdenum material loaded by carbon carrier in one step through high temperature calcination, which is applied to fireproof coating as flame-retardant and smoke-suppressant, promotes charring of polymer in fireproof coating, reduces smoke volume, and improves comprehensive performance of fireproof coating. The equal volume impregnation method can ensure that the precursor salt can be completely dissolved in water, and the carbon source carrier can be completely wetted without excessive water, so as to ensure uniformity of dispersion of the precursor salt solution in the carrier and uniformity of material preparation. If the water is too much, the precursor salt concentration in the surface layer is greater than that in the internal part of the carbon source carrier in the process of later drying, and the material is not uniform.

[0015] In an optional embodiment, the preparation method of the heteroatom enhanced molybdenum-based flame-retardant and smoke-suppressant comprises the following steps:

[0016] S1, preparing a precursor

[0017] S11, weighing the solid-phase carbon source, and adding deionized water drop by drop, and recording the required water amount when the water just wets the carbon source without excessive water;

[0018] S12, weighing molybdenum salt and salt containing heteroatoms according to the proportion, and dissolving with the same water amount as step S11;

[0019] S13, weighing the solid-phase carbon source according to the proportion, and pouring the solution obtained in step S12, stirring uniformly, and then immersing at room temperature;

[0020] S14, drying the mixture after immersion in step S13 to obtain a precursor of the heteroatom enhanced flame-retardant and smoke-suppressant;

[0021] S2, preparing a loaded heteroatom enhanced flame-retardant and smoke-suppressant

[0022] S21, placing the precursor in a tube furnace;

[0023] S22, introducing inert gas into the tube furnace;

[0024] S23, heating and keeping for 2-3h;

[0025] S24, after calcination, reducing to room temperature, introducing oxygen / inert gas mixture, and passivating for 8-20h;

[0026] S25, after passivation, taking out the sample, grinding, passing through a 200 mesh sieve, and reserving for use.

[0027] In step S11, the deionized water is added drop by drop, which helps the deionized water to better wet the carbon source and prevents the water from being too much due to too fast drop speed of the deionized water, exceeding the actual demand of the deionized water.

[0028] Optionally, in step S11, the solid-phase carbon source is one or more of activated carbon, graphene, graphene oxide, carbon nanotube, primary biomass, and carbon fiber.

[0029] Optionally, in step S12, the molybdenum salt is one or more of sodium molybdate, ammonium molybdate, and potassium molybdate.

[0030] Optionally, in step S12, the heteroatom-containing salt is one or more of urea, thiourea, melamine, ammonium phosphomolybdate, phosphomolybdate, ammonium thiomolybdate, sodium phosphate, potassium phosphate, and aluminum tripolyphosphate.

[0031] Optionally, in step S12, the mass ratio of the molybdenum salt and the heteroatom-containing salt is 1:1 to 3:2.

[0032] Optionally, in step S13, the mass ratio of the solid-phase carbon source and the molybdenum salt is 3:2 to 4:1.

[0033] Optionally, in step S13, the soaking time is 12 to 30 hours; more preferably, the soaking time is 24 hours.

[0034] Optionally, in step S14, the drying method is high-temperature oven drying and / or freeze drying.

[0035] Optionally, in steps S22 and S24, the inert gas is nitrogen and / or argon.

[0036] Optionally, in steps S22 and S24, the gas is introduced at a flow rate of 30 to 50 mL / min.

[0037] Optionally, in step S23, the temperature is raised to 800 to 1000℃ at a rate of 10 to 20℃ / min.

[0038] Optionally, in step S24, the oxygen content in the oxygen / inert gas mixture is 1 to 2%. By controlling the oxygen content, the over-oxidation of the molybdenum-based flame-retardant and smoke-suppressant can be prevented, and the degree of oxidation can be controlled.

[0039] The fourth aspect of the present application provides a fireproof coating.

[0040] In an optional embodiment, the fireproof coating comprises the heteroatom-enhanced molybdenum-based flame-retardant and smoke-suppressant according to the second aspect of the present application.

[0041] The fifth aspect of the present application provides an application of the fireproof coating.

[0042] In an optional embodiment, the fireproof coating is applied to the surface of a steel structure.

[0043] The present application has the following beneficial effects,

[0044] (1) The present application uses a one-step method to prepare carbon carrier loaded heteroatom modified molybdenum carbide. On the one hand, the Lewis acidity of molybdenum carbide is enhanced by heteroatom modification. On the other hand, the dispersion uniformity of molybdenum carbide on the carrier is improved by the form of loading, thereby improving the utilization rate of molybdenum carbide in the fireproof coating and the flame-retardant and smoke-suppressing effect.

[0045] (2) The heteroatom enhanced flame-retardant and smoke-suppressing agent in the present application promotes the polymer system to form char through Lewis acid catalysis, increases the amount of residual char, forms a carbon layer with more compact and uniform structure, reduces the amount of smoke, and significantly improves the fireproof and heat-insulating performance.

[0046] (3) The present application has the advantages of simple operation method, low cost, universality, and easy scale production. BRIEF DESCRIPTION OF DRAWINGS

[0047] Figure 1 is the sample appearance of the coating after burning of the control group shown in an embodiment of the present application;

[0048] Figure 2 is the sample appearance of the coating after burning of the coating added with Example 1 shown in an embodiment of the present application;

[0049] Figure 3 is the sample appearance of the coating after burning of the coating added with Example 4 shown in an embodiment of the present application;

[0050] Figure 4 is the sample appearance of the coating after burning of the coating added with Example 5 shown in an embodiment of the present application;

[0051] Figure 5 is the vertical burning method test machine and flame shown in an embodiment of the present application, wherein a is the test machine and b is the flame. DETAILED DESCRIPTION

[0052] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0053] Example 1

[0054] S1, Preparation of precursor

[0055] S11, take 20g activated carbon, drop in deionized water, stop dropping when water wets activated carbon completely without extra water precipitating, total 10mL water is needed;

[0056] S12, take 10g ammonium molybdate tetrahydrate and 3g urea, dissolve in 10mL deionized water, and continuously stir until completely dissolved without residue;

[0057] S13, take 20g activated carbon, and drop the mixed solution of ammonium molybdate and urea into dry 20g activated carbon under stirring, and stir uniformly;

[0058] S14, after 24h of immersion at room temperature, transfer the sample to a 120℃ oven, dry for 12h to obtain ammonium molybdate and urea-impregnated activated carbon precursor;

[0059] S15, grind the dried ammonium molybdate and urea-impregnated activated carbon precursor for later use.

[0060] S2, preparation of supported nitrogen atom enhanced molybdenum carbide

[0061] S21, place the ammonium molybdate and urea-impregnated activated carbon precursor in a tube furnace, and pass nitrogen at a flow rate of 30mL / min;

[0062] S22, increase the temperature to 850℃ at a rate of 10℃ / min, and maintain for 3h;

[0063] S23, after completion of calcination, reduce to room temperature;

[0064] S24, pass oxygen / nitrogen mixed gas with 1% oxygen content under room temperature conditions, and passivate for 12h;

[0065] S25, after passivation is completed, obtain activated carbon-supported nitrogen atom enhanced molybdenum carbide material; take out the sample, grind, pass through a 200 mesh sieve, and reserve for later use.

[0066] Example 2

[0067] S1, preparation of precursor

[0068] S11, take 20g graphene oxide, drop in deionized water, stop dropping when water wets graphene oxide completely without extra water precipitating, total 8mL water is needed;

[0069] S12, take 10g ammonium thiomolybdate, dissolve in 8mL deionized water, and continuously stir until completely dissolved without residue;

[0070] S13, take 20g graphene oxide, and drop the ammonium thiomolybdate solution into dry 20g graphene oxide under stirring, and stir uniformly;

[0071] S14, after 24h of immersion at room temperature, the sample is transferred to an oven at 140°C for 10h to obtain the ammonium thiomolybdate impregnated graphene oxide precursor;

[0072] S15, the dried ammonium thiomolybdate impregnated graphene oxide precursor is ground and stored.

[0073] S2, preparation of supported phosphorus atom enhanced molybdenum carbide

[0074] S21, the ammonium thiomolybdate impregnated graphene oxide precursor is placed in a tube furnace, and nitrogen gas is passed at a flow rate of 35mL / min;

[0075] S22, the temperature is raised to 800°C at a rate of 10°C / min and maintained for 2h;

[0076] S23, after the completion of the calcination, the temperature is lowered to room temperature;

[0077] S24, under room temperature conditions, oxygen / nitrogen mixed gas with an oxygen content of 1.5% is passed, and passivation is carried out for 12h;

[0078] S25, after the completion of the passivation, the graphene oxide supported sulfur atom enhanced molybdenum carbide material is obtained; the sample is removed, ground, and sieved through a 200 mesh sieve for storage.

[0079] Example 3

[0080] S1, preparation of the precursor

[0081] S11, 25g of cellulose (primary biomass) is weighed, and deionized water is added dropwise; when the water has completely wetted the cellulose without the separation of excess water, the dropwise addition is stopped, and a total of 15mL of water is required;

[0082] S12, 13g of sodium molybdate and 5g of sodium phosphate are weighed and dissolved in 15mL of deionized water, and constant stirring is carried out until complete dissolution without the presence of undissolved residues;

[0083] S13, 25g of cellulose is weighed, and the sodium molybdate and sodium phosphate mixed solution is added dropwise to the 25g of cellulose under stirring, and stirring is carried out until uniform;

[0084] S14, after 24h of immersion at room temperature, the sample is transferred to an oven at 130°C for 10h to obtain the sodium molybdate and sodium phosphate impregnated cellulose precursor;

[0085] S15, the dried sodium molybdate and sodium phosphate impregnated cellulose precursor is ground and stored.

[0086] S2, preparation of supported phosphorus atom enhanced molybdenum carbide

[0087] S21, the cellulose precursor impregnated with sodium molybdate and sodium phosphate is placed in a tube furnace, argon is passed at a flow rate of 40 mL / min;

[0088] S22, the temperature is raised to 1000°C at a rate of 20°C / min and maintained for 2.5 h;

[0089] S23, after the completion of calcination, the temperature is lowered to room temperature;

[0090] S24, under room temperature conditions, oxygen / nitrogen mixed gas with an oxygen content of 2% is passed, and passivation is performed for 10 h;

[0091] S25, after the completion of passivation, a cellulose-supported phosphorus atom-enhanced molybdenum carbide material is obtained; the sample is taken out, ground, and passed through a 200-mesh sieve for standby use.

[0092] Example 4

[0093] S1, preparation of the precursor

[0094] S11, 30 g of carbon nanotubes are weighed, and deionized water is added dropwise; when the water completely wets the carbon nanotubes without the precipitation of excess water, the dropwise addition is stopped, and a total of 16 mL of water is required;

[0095] S12, 15 g of sodium molybdate dihydrate and 5 g of thiourea are weighed and dissolved in 16 mL of deionized water, and constant stirring is performed until complete dissolution without residue of undissolved substances;

[0096] S13, 30 g of carbon nanotubes are weighed, and the mixed solution of sodium molybdate and thiourea is added dropwise to the dry 30 g of carbon nanotubes under stirring, and stirring is performed until uniform;

[0097] S14, after 24 h of impregnation at room temperature, the sample is transferred to a 150°C oven, and drying is performed for 8 h to obtain the carbon nanotube precursor impregnated with sodium molybdate and thiourea;

[0098] S15, the dried carbon nanotube precursor impregnated with sodium molybdate and thiourea is ground for standby use.

[0099] S2, preparation of a supported nitrogen-sulfur atom co-enhanced molybdenum carbide

[0100] S21, the carbon nanotube precursor impregnated with sodium molybdate and thiourea is placed in a tube furnace, and nitrogen is passed at a flow rate of 45 mL / min;

[0101] S22, the temperature is raised to 1000°C at a rate of 15°C / min and maintained for 3 h;

[0102] S23, after the completion of calcination, the temperature is lowered to room temperature;

[0103] S24, under room temperature conditions, oxygen / nitrogen mixed gas with an oxygen content of 1% is passed, and passivation is performed for 15 h;

[0104] S25, after passivation, carbon nanotube loaded nitrogen sulfur atom co-enhanced molybdenum carbide material is obtained; the sample is taken out, ground, and passed through a 200 mesh sieve for standby use.

[0105] Example 5

[0106] S1, preparation of precursor

[0107] S11, 30g of shell powder (primary biomass) is weighed, and deionized water is added dropwise; when the water wets the shell powder completely without excess water, the dropwise addition is stopped, and a total of 18mL of water is needed;

[0108] S12, 15g of potassium molybdate, 5g of thiourea, and 5g of potassium phosphate are weighed and dissolved in 18mL of deionized water, and continuously stirred until completely dissolved without residue;

[0109] S13, 30g of shell powder is weighed, and the mixed solution of potassium molybdate, thiourea, and potassium phosphate is added dropwise to the dry 30g of shell powder under stirring, and stirred uniformly;

[0110] S14, after 24h of immersion at room temperature, the sample is transferred to a refrigerator for 12h of freezing;

[0111] S15, the frozen sample is transferred to a freeze dryer for 24h of freeze drying, and a shell powder precursor impregnated with potassium molybdate, thiourea, and potassium phosphate is obtained;

[0112] S16, the dried shell powder precursor impregnated with potassium molybdate, thiourea, and potassium phosphate is ground for standby use.

[0113] S2, preparation of nitrogen phosphorus sulfur atom co-enhanced molybdenum carbide

[0114] S21, the shell powder precursor impregnated with potassium molybdate, thiourea, and potassium phosphate is placed in a tube furnace, and argon is passed at a flow rate of 50mL / min;

[0115] S22, the temperature is increased to 1000℃ at a rate of 20℃ / min, and maintained for 3h;

[0116] S23, after the calcination is completed, the temperature is reduced to room temperature;

[0117] S24, under the condition of room temperature, oxygen / nitrogen mixed gas with an oxygen content of 1.5% is passed, and passivated for 15h;

[0118] S25, after passivation, a shell powder loaded nitrogen phosphorus sulfur atom co-enhanced molybdenum carbide material is obtained; the sample is taken out, ground, and passed through a 200 mesh sieve for standby use.

[0119] The flame-retardant smoke-suppressing agent prepared in the above-mentioned examples 1 to 5 is applied to a fireproof coating for steel structure, a silicone-acrylate emulsion is used as a film-forming material, ammonium polyphosphate, pentaerythritol and melamine are used as an intumescent flame-retardant system, and the flame-retardant smoke-suppressing performance of the fireproof coating after adding the flame-retardant smoke-suppressing agent is studied. The application effect of the heteroatom-enhanced molybdenum-based flame-retardant smoke-suppressing agent in the fireproof coating is characterized by a vertical burning method, a thermogravimetric analysis method and the like. Since the carbonization of a high polymer and the smoke suppression are closely related, the quality and formation of a carbon layer can effectively suppress the generation and release of smoke; correspondingly, the generation and rapid diffusion of smoke are often not conducive to the formation of the carbon layer. Therefore, the residual carbon content of the fireproof coating is characterized by the thermogravimetric analysis method, and the flame-retardant smoke-suppressing effect of the molybdenum-based flame-retardant smoke-suppressing agent is measured in combination with the flame-retardant effect obtained by the vertical burning method. The fireproof coating without adding any flame-retardant smoke-suppressing agent is used as a control group, and the heteroatom-enhanced molybdenum-based flame-retardant smoke-suppressing agent prepared in examples 1 to 5 is used as a test group for comparison test.

[0120] According to the large plate burning method in GB 12441-2005 “facing fireproof coating”, the appearance of the sample after burning is shown in Figures 1 to 4 According to the vertical burning method in GB / T 2408-2021 “determination of the burning performance of plastics by horizontal and vertical methods”, the flame-retardant performance is tested in a burning tester Figure 5 ); the thermogravimetric analysis method is used in an air atmosphere, and the temperature is raised to 800℃ at a rate of 10℃ / min, and the results are shown in Table 1.

[0121] Table 1

[0122] Item Control group Examples 1-3 Example 4 Example 5 Vertical burning rating V-1 V-0 V-0 V-0 Amount of carbon residue after thermal decomposition 15％ 20％-25％ 30％ 35％ Carbon layer strength Generally Stronger Stronger Strong

[0123] Of course, the above description is not a limitation of the present application, and the present application is not limited to the above examples, and the changes, modifications, additions or replacements made by the person skilled in the art within the essential scope of the present application should also belong to the protection scope of the present application.

Claims

1. A method for producing a heteroatom-enhanced molybdenum-based flame- retardant smoke suppressant, characterized by, The method comprises the following steps: S1, preparing a precursor S11, weighing a solid-phase carbon source and adding deionized water drop by drop, and recording the required water amount when the water just wets the carbon source without excess water amount; S12, weighing molybdenum salt and salt containing heteroatoms according to a proportion, and dissolving with the same water amount as step S11; S13, weighing the solid-phase carbon source according to a proportion, and pouring the solution obtained in step S12 into the solid-phase carbon source, and stirring uniformly, and then immersing at room temperature; S14, drying the mixture after immersion in step S13 to obtain a precursor of the heteroatom-enhanced flame-retardant and smoke-suppressing agent; S2, preparing a supported heteroatom-enhanced flame-retardant and smoke-suppressing agent S21, placing the precursor in a tube furnace; S22, introducing inert gas into the tube furnace; S23, increasing the temperature and keeping for 2-3 hours; S24, after the calcination is completed, reducing to room temperature, and introducing oxygen / inert gas mixture to perform passivation; S25, after the passivation is completed, taking out the sample and grinding for use; In step S11, the solid-phase carbon source is one or more of activated carbon, graphene, graphene oxide, carbon nanotube, primary biomass, and carbon fiber; In step S12, the molybdenum salt is one or more of sodium molybdate, ammonium molybdate, and potassium molybdate; In step S12, the salt containing heteroatoms is one or more of urea, thiourea, melamine, sodium phosphate, potassium phosphate, and aluminum tripolyphosphate; In step S12, the mass ratio of the molybdenum salt and the salt containing heteroatoms is 1:1-3:2; In step S13, the mass ratio of the solid-phase carbon source and the molybdenum salt is 3:2-4:

1.

2. The preparation method of a heteroatom-reinforced molybdenum-based flame retardant and smoke suppressant as described in claim 1, characterized in that, In step S14, the drying mode is high-temperature oven drying and / or freeze drying.

3. The preparation method of a heteroatom-reinforced molybdenum-based flame retardant and smoke suppressant as described in claim 1, characterized in that, In steps S22 and S24, the inert gas is nitrogen and / or argon.

4. The preparation method of a heteroatom-reinforced molybdenum-based flame retardant and smoke suppressant as described in claim 1, characterized in that, In steps S22 and S24, the gas is introduced at a flow rate of 30-50 mL / min.

5. The preparation method of a heteroatom-reinforced molybdenum-based flame retardant and smoke suppressant as described in claim 1, characterized in that, In step S23, the temperature is increased to 800-1000℃ at a rate of 10-20℃ / min.

6. The preparation method of a heteroatom-reinforced molybdenum-based flame retardant and smoke suppressant as described in claim 1, characterized in that, In step S24, the oxygen content in the oxygen / inert gas mixture is 1-2%.

7. A fireproofing coating, characterized by The heteroatom-enhanced molybdenum-based flame-retardant and smoke-suppressing agent prepared by the method of any one of claims 1-6.

8. Use of a fireproofing coating as claimed in claim 7, characterised in that, Applied to the surface of a steel structure.

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