Cracking furnace tube coating material composition, cracking furnace tube coating and preparation method therefor

Abstract

The present invention provides a cracking furnace tube coating material composition, a cracking furnace tube coating and a preparation method therefor. The coating material composition comprises a first coating material and a second coating material; the first coating material comprises a catalytically active component, a complexing agent, a buffering agent and a dispersing agent; the second coating material is a liquid slurry or a solid particle mixture. The preparation method for the coating comprises: pretreating the surface of a base material; loading a first coating material, and after atmosphere stabilization treatment, forming a first coating; and loading a second coating material, and, after high-temperature thermal co-diffusion, obtaining the coating. With respect to the cracking furnace tube coating prepared from the coating material composition of the present invention, the catalytically active element contained therein has relatively high dispersity, and the catalytically active element is relatively stable.

Description

Cracking furnace tube coating material composition and cracking furnace tube coating and preparation method thereof Technical Field

[0001] The invention relates to a cracking furnace tube coating material composition and a cracking furnace tube coating and a preparation method thereof, and belongs to the technical field of olefin production in petrochemical industry. Background Art

[0002] Light olefins such as ethylene, propylene, and butadiene are essential chemical raw materials in the petrochemical industry. Ethylene production capacity has long been considered a hallmark of petrochemical development. Steam cracking, currently the primary ethylene production process, often involves thermally cracking hydrocarbon feedstocks at temperatures of 750-875°C to produce light olefins. To meet the required thermal cracking temperatures, steam cracking furnace tubes are often constructed from chromium-nickel alloys, which offer excellent high-temperature resistance. However, at high temperatures, the iron and nickel atoms in the alloy migrate to the outer surface of the substrate, where they accumulate on the tube surface and serve as catalytically active centers, accelerating the deposition of coke on the tubes. This accumulation of coke reduces the tube inner diameter, altering the flow of feed gas within the tubes and reducing the cracking furnace's feedstock processing capacity, negatively impacting ethylene production capacity. Furthermore, the high thermal resistance of the coke layer reduces the heat transfer efficiency of the cracking furnace tubes, increasing the furnace's operating energy consumption. Generally speaking, industrial cracking furnaces often need to be shut down for decoking after operating for 30 to 60 days. The decoking process often takes 48 hours or even longer before the cracking furnace tubes can be put back into production, which greatly limits the operating efficiency of the cracking furnace.

[0003] Currently, cracking furnace tube coating technology is the most effective means of inhibiting coking in cracking furnaces. This technology primarily involves applying one or more layers of coating to the inner surface of the cracking furnace tubes using physical or chemical methods. These coatings not only shield the tube substrate from catalytically active elements such as iron and nickel, but also reduce the corrosive effects of carburization on the cracking furnace tubes during ethylene production. This technology effectively inhibits coking in the cracking furnace tubes, significantly improving the operating cycle of the cracking furnace. Furthermore, the reduced coke buildup on the inner tube surface further reduces the furnace's operating energy consumption.

[0004] Currently, a variety of coating technologies have been developed in this field. Most of these coating technologies use inert coatings, which mainly play a shielding role on the iron and nickel elements in the furnace tube substrate. By preventing the formation of catalytic coke, the cracking furnace tubes can obtain good coking inhibition performance. However, these coating technologies are mostly difficult to effectively inhibit the free radical coking and condensation coking produced during the cracking process. To achieve a better coking inhibition effect, researchers have proposed a new catalytic coating technology. This technology introduces catalytically active elements into the coating. These catalytically active elements can catalyze the free radical coking and condensation coking produced during the cracking process into gaseous gases such as carbon monoxide and carbon dioxide. The application of this coating technology can significantly reduce the amount of coke generated during the cracking process and further extend the operating cycle of the cracking furnace.

[0005] CN112708445A discloses a cracking device. The inner wall of the reactor of the device comprises a substrate, a metal layer, a first catalytic coating and a second catalytic coating. The first catalytic coating comprises a composition of MnxCr 3‐x O4 manganese chromium oxygen complex, the second catalytic coating comprises a perovskite material composed of AMO3 and / or a composition of (Na2O) y A triclinic nepheline-like substance of Na2[Al2Si2O8]; wherein A is an alkaline earth metal element, and M is selected from at least one of Group IIIB elements and Group IVB elements. The specific steps for preparing the coating are: (1) applying a metal powder mixture to the surface of a substrate of a cracking device, and curing the metal powder mixture under vacuum or inert atmosphere to form a metal layer on the surface of the substrate of the cracking device; (2) performing a heat treatment under low oxygen partial pressure atmosphere and high temperature conditions to form a first catalytic coating on the surface of the metal layer; (3) preparing a second catalytic coating on the first catalytic coating. This technology uses vapor deposition to prepare the metal layer, the first catalytic coating, and the second catalytic coating. The prepared coating can reduce asphalt coking and free radical coking during the cracking process, and minimize coking during the cracking process as much as possible while maintaining the olefin yield in the cracking product basically unchanged. However, the coating slurry used in this technology only uses metal salts and silica-alumina sol. During the slurry preparation process, the dispersion of metal ions in the system is difficult to ensure. This makes it impossible for the metal elements to be highly dispersed on the substrate surface during the subsequent slurry deposition process, which limits the coating's ability to inhibit coking to a certain extent. In addition, the coating prepared by this technology has a multi-layer structure, and the preparation process is relatively complicated. At the same time, this technical solution does not explore the overall stability and mechanical strength of the coating.

[0006] CN105885486A discloses a composite coating for inhibiting coking of furnace tubes and a preparation method thereof. The main components of the composite coating are BaCeO3 powder and silica sol. The preparation method of the coating formed by the composite coating is mainly to mix BaCeO3 powder, silica sol and water in a certain proportion in advance to form a slurry, and then apply it on the surface of the substrate, and form a coating that inhibits coking by high-temperature calcination. The BaCeO3 powder in the coating plays a role in inhibiting coking, and the solid particle size is 1 to 3 microns. The coating was applied to a high-pressure thermal cracking device and a hydrocarbon fuel cracking experiment was carried out on the coating. The results showed that the furnace tube loaded with the coating had an inhibition rate of 56.5% on carbon deposition compared with the blank tube. Scanning electron microscopy showed that the coating was dense and the reaction tube was completely filled. After the cracking experiment, the coating structure was more compact and the overall morphology remained intact. Although the composite coating has good thermal conductivity and a high coking inhibition rate, the BaCeO3 powder prepared is micron-sized particles. Therefore, under high temperature conditions, the sintering phenomenon of the BaCeO3 particles in the coating will be more serious, which to a certain extent limits the coking inhibition effect of the coating.

[0007] CN102899067B discloses a cracking furnace tube. The cracking furnace tube comprises a cracking furnace tube substrate and an inert coating adhered to the inner wall surface of the cracking furnace tube substrate. The inert coating prevents coke from contacting the cracking furnace tube substrate and does not react with the cracking feedstock or cracking products. The inert coating has a porous structure with an average pore radius of 0.5 to 15 nm. An active catalytic layer may also be adhered to the surface of the inert coating. The inert coating contains silicon dioxide and / or a first metal oxide, wherein the metal in the first metal oxide is selected from one or more of aluminum, titanium, zirconium, manganese, chromium, lanthanum, and magnesium. The active catalytic layer contains a second metal active component, wherein the metal in the second metal active component is selected from one or more of lithium, sodium, potassium, rubidium, calcium, strontium, barium, molybdenum, cobalt, nickel, iron, copper, cerium, and praseodymium. The presence of the second metal active component enables the coating to catalyze the reaction between coke and water vapor. The preparation method of the coating mainly includes the following steps: (1) ultrasonically cleaning the substrate surface using acetone and deionized water; (2) preparing an inert coating slurry and applying the slurry to the surface of the cracking furnace tube substrate by an impregnation method, and obtaining an inert coating after high-temperature calcination; (3) preparing an active element salt solution, loading the active element on the surface of the inert coating by an impregnation method, and obtaining a cracking furnace tube loaded with the coating after high-temperature calcination. Although the coating prepared by this method has good anti-coking performance, since the active elements are loaded by the impregnation method, the active elements in the coating have obvious mutual agglomeration effects, and the active element dispersion is not high. In addition, the subsequent high-temperature heat treatment process will further promote the mutual agglomeration between the elements, which makes the bonding between the prepared catalytic active layer and the substrate weak, and the catalytic active elements cannot achieve the optimal catalytic coke conversion efficiency. On the other hand, this method does not study the stability of the prepared coating during repeated use.

[0008] CN103861662B discloses an anti-coking catalyst coating including an alumina barrier layer. The coating is a double-layer structure, including a catalyst layer and an alumina barrier layer, wherein the alumina barrier layer is prepared by pre-plating aluminum on the surface of a metal substrate and then subjecting the sample to high-temperature oxidation treatment. The main function of the alumina barrier layer is to inhibit the migration of catalytic coking elements inside the substrate to the outside, and prevent the catalytic coking elements from being enriched on the coating surface. The catalyst layer is mainly composed of BaCe x Zr (1-x)The anti-coking catalyst coating is composed of O3-type perovskite compounds, which are prepared by solid powder roasting method. The main function of the catalyst layer is to catalyze the conversion of coke formed during the thermal cracking of heavy oil products, and convert the coke into gases such as CO or CO2. The anti-coking catalyst coating was subjected to a 200-hour fatigue test and a simulated cracking test. The results showed that the oxidant coating has good anti-coking performance. Although the anti-coking catalyst coating prepared by this method has good anti-coking performance and service life. However, since this method uses a solid powder roasting method to prepare the catalyst BaCe x Zr (1-x) O3 perovskite compounds, produced by solid powder calcination methods, often suffer from large particle size, which can affect the dispersion of the perovskite compound in the catalyst coating, thereby limiting the catalytic activity of the catalyst coating. Furthermore, the catalyst layer is loaded by coating and calcining the barrier layer, resulting in a weak bond between the catalyst layer and the barrier layer. This impact on the coating's service life remains to be further verified.

[0009] CN1546609A discloses a method for inhibiting and slowing down the coking of ethylene cracking furnace tubes. The method comprises the following steps: (1) using a mixed gas containing H2, N2, and trace amounts of NH3, H2O, and O2, generated by the decomposition of liquid ammonia, as a reducing gas to treat the furnace tubes with an atmosphere, and then cooling the furnace tubes after the treatment; (2) preparing a slurry by mixing a prepared alloy powder and a binder, applying the slurry to the surface of the furnace tubes after the atmosphere treatment, drying and solidifying the slurry, and then placing the slurry in a heating furnace for high-temperature diffusion treatment. After the treatment, the furnace tubes are cooled and the excess alloy powder coating on the surface of the furnace tubes is removed, thereby forming an alloy layer on the surface of the furnace tubes that can inhibit and slow down coking. The alloy powder used in this technology is composed of aluminum, silicon, chromium, rare earth, a catalyst, and a dispersant. The catalyst is mainly ammonium chloride, sodium fluoride, or cryolite. The alloy layer produced by this technology can be more than 100 microns thick and has a good coking inhibition effect. The binders used in this technology are mainly edible gelatin and polyvinyl alcohol. While this coating exhibits excellent coking inhibition, reducing coking by up to 90%, uneven mixing of elements in the slurry during the preparation process can lead to significant variations in element distribution across different coating regions. This results in varying coking inhibition performance and coke deposition within each region. Furthermore, uneven heating of the coating surface can cause thermal shock, making the coating structure susceptible to damage.

[0010] CN101724827A discloses a method for reducing coking in ethylene cracking furnace tubes and improving ethylene selectivity. The method comprises the following steps: (1) injecting a pre-treated solution containing ceramic elements and active component elements of a catalytic cracking catalyst into the cracking furnace along with a carrier gas at the crossover temperature front end of the cracking reaction, and performing vapor deposition at 500°C to 1000°C; wherein the ceramic elements are mainly Si, Al, Ca, B, and the catalytically active elements are mainly Ag, Cr, Cu, Ti, and the solvent of the pre-treated solution is an ethanol solution; (2) after the vapor deposition, the metal oxides deposited on the inner wall of the furnace tube are passivated in an atmosphere of a carrier gas mainly composed of an inert gas at 700°C to 1100°C to form a coating. The coking inhibition performance of the coating was tested using industrial naphtha as the cracking raw material. The results showed that the coating can reduce coke deposition on the inner wall of the furnace tube by more than 80% and increase the volume percentage of ethylene in the product by 4.32%. The coating prepared by this method contains inert ceramic elements and catalytically active elements. The preparation steps are to load the two elements onto the substrate surface in a one-step process, followed by a high-temperature passivation treatment to obtain the coating. Although the coating can significantly reduce coke formation when used in naphtha cracking reactions, repeated test data shows that the coke reduction of the coating prepared by this method decreases from 92.97% to 73.29% during repeated use. The coating's coking inhibition performance has declined significantly, indicating that the catalytically active elements in the coating have migrated and lost, and the overall stability of the coating is poor.

[0011] In summary, if you want to make the cracking furnace tube coating have the function of catalyzing the gasification and conversion of coke, the existing technology mostly adopts the introduction of active elements such as Li, Na, K, Ru, Ce into the coating during the coating preparation process. The conventional introduction method mostly adopts the inert element component and the active element component to be dispersed in a solvent to form a slurry, and the above elements are loaded on the surface of the substrate by coating, vapor deposition, solid powder embedding and other methods. After subsequent high-temperature heat treatment, the elements are combined with each other and co-infiltrated into the substrate alloy phase to form the required coating. Although the existing catalytic coating technology has a relatively good catalytic coking inhibition performance during the application process, the active elements in the slurry often agglomerate, making it difficult for the active elements to be highly dispersed on the surface of the substrate. The coking inhibition performance of different areas of the prepared coating is not the same, so that in actual use, different areas of the coating often have different thermal resistance coefficients due to different coke deposition amounts, which can easily cause overheating of local areas of the cracking furnace tube, reducing the service life of the coating and the furnace tube. On the other hand, under the environment of high-temperature oxidation and continuous thermal shock, the bonding force between the coating elements and the substrate gradually weakens due to the combined effects of their own migration and high-temperature carburization, causing the coating to peel off from the substrate surface, destroying the coating structure and causing it to lose its protective function for the substrate.

[0012] Summary of the Invention

[0013] To address the above-mentioned technical problems, the present invention provides a cracking furnace tube coating material composition, a cracking furnace tube coating, and a method for preparing the same. The cracking furnace tube coating prepared using the coating material composition of the present invention has a highly dispersed and more stable catalytically active element within it, with minimal element migration within the coating.

[0014] To achieve the above-mentioned object, the present invention provides a first aspect of a cracking furnace tube coating material composition, which comprises: a first coating material and a second coating material;

[0015] Wherein, based on the total mass of the first coating material as 100%, it includes the following components: 10-40% of a catalytically active component, 2-30% of a complexing agent, 5-20% of a buffer, and 40-70% of a first dispersant; the catalytically active component includes one or a combination of compounds of alkali metal elements, compounds of alkaline earth metal elements, compounds of rare earth metal elements, and compounds of transition metal elements;

[0016] The second coating material is a liquid slurry or a solid particle mixture; based on the total mass of the liquid slurry as 100%, it includes the following components: 10-65% of an inert protective component, 0.1-3.0% of a flux, 1.0-5.0% of an activator, 20-80% of a filler and the remainder of a second dispersant; based on the total mass of the solid particle mixture as 100%, it includes the following components: 15-60% of an inert protective component, 0.1-2.5% of a flux, 1.0-6.0% of an activator and the remainder of a filler.

[0017] In the above coating material composition, preferably, based on the total mass of the first coating material being 100%, it includes the following components: 10-29% catalytic active component, 5-15% complexing agent, 5-15% buffer and 40-70% first dispersant.

[0018] In the above-mentioned coating material composition, preferably, in the components of the first coating material, the alkali metal elements include one or more combinations of Li, Na and K; the alkaline earth metal elements include one or more combinations of Mg, Ca, Sr and Ba; the rare earth metal elements include one or more combinations of La, Ce, Pr, Nd and Y; the transition metal elements include one or more combinations of Co, Mn, Mo, Cu, Zn, V, Ti, Cr, W, Rh and Hf.

[0019] In the above-mentioned coating material composition, preferably, among the components of the first coating material, the complexing agent includes one or a combination of disodium nitrilotriacetate, disodium ethylenediaminetetraacetate, dithizone, 8-hydroxyquinoline, o-phenanthroline, potassium sodium tartrate and polyphosphate.

[0020] In the above-mentioned coating material composition, preferably, among the components of the first coating material, the buffer comprises one or a combination of ammonium acetate, tris(hydroxymethyl)aminomethane, and citrate.

[0021] In the above-mentioned coating material composition, preferably, among the components of the first coating material, the first dispersant includes one or a combination of deionized water, ethanol, ethylene glycol, acetone and chloroform.

[0022] In the above-mentioned coating material composition, preferably, the first coating material is prepared by at least the following steps: (a) mixing the catalytically active component, the buffer and a portion of the first dispersant, and stirring to form a mixed system; (b) mixing the complexing agent and another portion of the first dispersant to obtain a complexing agent solution; (c) adding the complexing agent solution obtained in step (b) dropwise to the mixed system obtained in step (a) under stirring conditions, and continuing to stir for a period of time after the addition is completed to obtain the first coating material.

[0023] In the above-mentioned coating material composition, preferably, based on the total mass of the liquid slurry as 100%, it includes the following components: 15-60% of inert protective component, 0.1-2.5% of flux, 1.0-2.0% of activator, 24-70% of filler and the balance of second dispersant.

[0024] In the above coating material composition, preferably, based on the total mass of the solid particle mixture as 100%, it includes the following components: 24-58% inert protective component, 0.1-2.5% flux, 1.1-4.0% activator and the balance filler.

[0025] In the above-mentioned coating material composition, preferably, among the components of the second coating material, the inert protective component includes one or a combination of chromium, silicon, and aluminum.

[0026] In the above-mentioned coating material composition, preferably, among the components of the second coating material, the flux includes one or a combination of chromium fluoride, sodium fluoride, zirconium chloride and potassium fluoride.

[0027] In the above-mentioned coating material composition, preferably, among the components of the second coating material, the activator includes one or a combination of ammonium chloride, ammonium fluoride and ammonium sulfate.

[0028] In the above coating material composition, preferably, among the components of the second coating material, the filler includes aluminum oxide or the like.

[0029] In the above-mentioned coating material composition, preferably, among the components of the second coating material, the second dispersant includes one or a combination of deionized water, ethanol, ethylene glycol, acetone and chloroform.

[0030] In the cracking furnace tube coating material composition of the present invention, the first coating material and the second coating material can be stored separately. When preparing the coating, the first coating material and the second coating material are combined to form a coating layer.

[0031] A second aspect of the present invention provides a method for preparing a cracking furnace tube coating, wherein the method uses the above-mentioned cracking furnace tube coating material composition to form a coating, and the method comprises the following steps:

[0032] (1) Pre-treating the substrate surface;

[0033] (2) loading a first coating material on the surface of the pretreated substrate, and then performing an atmosphere stabilization treatment to form a first coating;

[0034] (3) The second coating material is loaded on the surface of the first coating, and then subjected to high-temperature thermal co-infiltration to obtain the cracking furnace tube coating.

[0035] In the above preparation method, preferably, in step (1), the method of pre-treating the surface of the substrate includes immersing the substrate in an inorganic acid solution.

[0036] In the above preparation method, preferably, in step (2), the loading method of the first coating material includes one or a combination of liquid phase brushing, atomization spraying, physical vapor deposition, chemical vapor deposition and immersion.

[0037] In the above preparation method, preferably, in step (2), the loading amount of the first coating on the pretreated substrate surface is 74 to 370 g / m 2 .

[0038] In the above-mentioned preparation method, preferably, in step (2), the atmosphere stabilization treatment includes: using a mixture of nitrogen and hydrogen as a stabilization treatment atmosphere, in the stabilization treatment atmosphere, using programmed temperature increase to heat the substrate loaded with the first coating material to a stabilization treatment temperature, and after reaching the stabilization treatment temperature, maintaining the temperature at a constant level for a period of time to complete the atmosphere stabilization treatment.

[0039] In the above preparation method, preferably, in the atmosphere stabilization treatment in step (2), the stabilization treatment temperature is 500-750°C.

[0040] In the above preparation method, preferably, in the atmosphere stabilization treatment in step (2), the constant temperature is maintained for 3 to 7 hours.

[0041] In the above preparation method, preferably, in step (3), the second coating material is loaded by liquid coating or solid powder embedding. It will be understood by those skilled in the art that when the second coating material is a liquid slurry, liquid coating is used for loading; when the second coating material is a solid particle mixture, solid powder embedding is used for loading.

[0042] In the above preparation method, preferably, in step (3), the high-temperature thermal co-infiltration includes: performing high-temperature heat treatment on the substrate loaded with the second coating material.

[0043] In the above-mentioned preparation method, preferably, in the high-temperature thermal co-infiltration of step (3), the temperature of the high-temperature heat treatment is 850-1200° C., and the constant temperature is maintained for 4-9 hours.

[0044] In the above preparation method, preferably, in step (3), the high-temperature thermal co-diffusion is carried out in a protective atmosphere, and the protective atmosphere includes nitrogen and / or argon, etc.

[0045] A third aspect of the present invention provides a cracking furnace tube coating, which is prepared by the above-mentioned method for preparing the cracking furnace tube coating.

[0046] According to a specific embodiment of the present invention, preferably, the thickness of the cracking furnace tube coating is 20 to 300 μm.

[0047] The technical solution of the present invention has at least the following beneficial effects:

[0048] The cracking furnace tube coating prepared from the coating material composition of the present invention is a ceramic coating. While the ceramic coating has the function of high-temperature protection for the substrate, it also has the function of catalytic gasification conversion of coke generated during the hydrocarbon cracking process. The ceramic coating has excellent mechanical properties, thermal corrosion resistance and sintering resistance. The catalytically active elements contained in the coating have a high degree of dispersion, so that the coating has an excellent inhibitory effect on coke during application. At the same time, the catalytically active elements contained in the coating are relatively stable. During repeated use, the overall element migration phenomenon in the coating is less, and the element loss is low. Therefore, the ceramic coating can effectively inhibit the coking of the cracking furnace tube and increase the service life of the cracking furnace tube. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] FIG1 is a cross-sectional SEM photograph of the ceramic coating prepared in Example 1.

[0050] FIG2 is a mapping energy spectrum of catalytically active elements on the surface of the ceramic coating prepared in Example 1.

[0051] FIG3 is a mapping energy spectrum of catalytically active elements on the surface of the ceramic coating prepared in Comparative Example 3.

[0052] FIG4 is a distribution diagram of catalytically active elements in a cross section of the ceramic coating prepared in Example 1.

[0053] FIG5 is a graph showing the coking inhibition rates of the coatings prepared in Example 1, Example 6, Example 11, and Comparative Example 2 as a function of the usage cycle. DETAILED DESCRIPTION

[0054] In order to have a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention is now described in detail below, but it should not be understood as limiting the scope of implementation of the present invention.

[0055] A first aspect of the present invention provides a cracking furnace tube coating material composition, comprising: a first coating material and a second coating material;

[0056] Wherein, based on the total mass of the first coating material as 100%, it includes the following components: 10-40% of a catalytically active component, 2-30% of a complexing agent, 5-20% of a buffer, and 40-70% of a first dispersant; the catalytically active component includes one or a combination of compounds of alkali metal elements, compounds of alkaline earth metal elements, compounds of rare earth metal elements, and compounds of transition metal elements;

[0057] The second coating material is a liquid slurry or a solid particle mixture; based on the total mass of the liquid slurry as 100%, it includes the following components: 10-65% of an inert protective component, 0.1-3.0% of a flux (preferably 0.1-2.5%), 1.0-5.0% of an activator, 20-80% of a filler and the remainder of a second dispersant; based on the total mass of the solid particle mixture as 100%, it includes the following components: 15-60% of an inert protective component, 0.1-2.5% of a flux, 1.0-6.0% of an activator and the remainder of a filler.

[0058] In some specific embodiments of the present invention, based on the total mass of the first coating material being 100%, it includes the following components: 10-29% catalytic active component, 5-15% complexing agent, 5-15% buffer and 40-70% first dispersant.

[0059] In some specific embodiments of the present invention, the alkali metal elements include one or more combinations of Li, Na and K, preferably Li and / or K; the alkaline earth metal elements include one or more combinations of Mg, Ca, Sr and Ba, preferably one or more combinations of Mg, Ca and Ba; the rare earth metal elements include one or more combinations of La, Ce, Pr, Nd and Y, preferably one or more combinations of La, Ce and Y; the transition metal elements include one or more combinations of Co, Mn, Mo, Cu, Zn, V, Ti, Cr, W, Rh and Hf, preferably one or more combinations of Ti, Cr and W.

[0060] In some specific embodiments of the present invention, the compounds of alkali metal elements, the compounds of alkaline earth metal elements, the compounds of rare earth metal elements and the compounds of transition metal elements may include salt compounds of these metal elements, and may also include organic compounds of these metal elements, preferably salt compounds of these metal elements, such as nitrates, chlorides, etc.

[0061] In some specific embodiments of the present invention, the complexing agent includes one or a combination of disodium nitrilotriacetate, disodium ethylenediaminetetraacetate, dithizone, 8-hydroxyquinoline, o-phenanthroline, potassium sodium tartrate and polyphosphate.

[0062] In some embodiments of the present invention, the buffer comprises one or a combination of ammonium acetate, tris(hydroxymethyl)aminomethane and citrate.

[0063] In some specific embodiments of the present invention, the first dispersant includes one or a combination of deionized water, ethanol, ethylene glycol, acetone, and chloroform, etc. Preferably, the first dispersant includes deionized water and / or ethanol.

[0064] In some specific embodiments of the present invention, the pH value of the first coating material is 4-9.

[0065] In some specific embodiments of the present invention, the first coating material is prepared by at least the following steps: (a) mixing the catalytically active component, the buffer and a portion of the first dispersant, and stirring to form a mixed system; (b) mixing the complexing agent and another portion of the first dispersant to obtain a complexing agent solution; (c) adding the complexing agent solution obtained in step (b) dropwise to the mixed system obtained in step (a) under stirring conditions, and continuing to stir for a period of time after the addition is completed to obtain the first coating material.

[0066] In some specific embodiments of the present invention, the preparation step (a) of the first coating material is carried out under a constant temperature condition, and the constant temperature is 20-50°C, preferably 30-40°C.

[0067] In some specific embodiments of the present invention, in the preparation step (a) of the first coating material, the stirring speed is 200 to 600 rpm, preferably 200 to 450 rpm.

[0068] In some specific embodiments of the present invention, in the step (b) of preparing the first coating material, the concentration of the complexing agent solution is 0.01 to 1 mol / L, preferably 0.1 to 1 mol / L.

[0069] In some specific embodiments of the present invention, in the step (c) of preparing the first coating material, the dropwise addition rate of the complexing agent solution is 0.1 to 5 mL / min, preferably 0.5 to 3 mL / min.

[0070] In some specific embodiments of the present invention, step (c) of preparing the first coating material is carried out under constant temperature conditions, and the constant temperature is 20-50°C, preferably 30-40°C.

[0071] In some specific embodiments of the present invention, in the step (c) of preparing the first coating material, the stirring speed is 200-300 rpm.

[0072] In some specific embodiments of the present invention, in the step (c) of preparing the first coating material, the stirring time after the dropwise addition is completed is 20 to 75 minutes.

[0073] The catalytically active component employed in the present invention includes one of an alkali metal element, an alkaline earth metal element, a rare earth metal element, or a transition metal element, or a composite solid solution of several of these elements. Therefore, the coating provided by the present invention not only provides high-temperature protection for the substrate, but also catalyzes the gasification and conversion of coke generated during hydrocarbon cracking.

[0074] Existing catalytic coating technologies require the pre-preparation of a catalytic coating slurry, followed by coating and high-temperature heat treatment to form the desired coating. During slurry preparation, the catalytically active components are directly injected, so thorough mixing of the slurry is a key factor affecting their dispersion within the coating. During mixing, the catalytically active components often agglomerate into large particles, reducing their dispersion within the coating and ultimately limiting the catalytic coating's ability to inhibit coking.

[0075] The present invention introduces a complexing agent into the first coating material, and adjusts the complexing effect of the complexing agent on the catalytically active components by controlling the pH value of the first coating material, the temperature of the preparation process, the stirring rate and other conditions, thereby effectively reducing the agglomeration effect between the catalytically active components in the first coating material.

[0076] In some specific embodiments of the present invention, based on the total mass of the liquid slurry being 100%, it includes the following components: 15-60% of an inert protective component, 0.1-2.5% of a flux, 1.0-2.0% of an activator, 24-70% of a filler, and the remainder of a second dispersant.

[0077] In some specific embodiments of the present invention, based on the total mass of the solid particle mixture as 100%, it includes the following components: 24-58% of inert protective component, 0.1-2.5% of flux (preferably 0.1-2.0%), 1.1-4.0% of activator and the balance of filler.

[0078] In some specific embodiments of the present invention, the inert protective component includes one or a combination of chromium, silicon, and aluminum.

[0079] In some specific embodiments of the present invention, the flux includes one or a combination of chromium fluoride, sodium fluoride, zirconium chloride and potassium fluoride.

[0080] In some specific embodiments of the present invention, the activator includes one or a combination of ammonium chloride, ammonium fluoride and ammonium sulfate.

[0081] In some specific embodiments of the present invention, the filler includes aluminum oxide or the like.

[0082] In some specific embodiments of the present invention, the particle sizes of the inert protective component and the filler are respectively 100-350 meshes.

[0083] In some specific embodiments of the present invention, the second dispersant includes one or a combination of deionized water, ethanol, ethylene glycol, acetone, and chloroform, etc. Preferably, the second dispersant includes deionized water and / or ethanol.

[0084] In some specific embodiments of the present invention, the second coating material is prepared by stirring and mixing the components. Preferably, during the preparation of the second coating material, the components are stirred and mixed for 0.5 to 10 hours.

[0085] A second aspect of the present invention provides a method for preparing a cracking furnace tube coating, wherein the method uses the above-mentioned cracking furnace tube coating material composition to form a coating, and the method comprises the following steps:

[0086] (1) Pre-treating the substrate surface;

[0087] (2) loading a first coating material on the surface of the pretreated substrate, and then performing an atmosphere stabilization treatment to form a first coating;

[0088] (3) The second coating material is loaded on the surface of the first coating, and then subjected to high-temperature thermal co-infiltration to obtain the cracking furnace tube coating.

[0089] In some specific embodiments of the present invention, the substrate is a high temperature resistant alloy steel, including GH series alloys, NS series alloys, or Incoloy series alloys, etc. Preferably, the GH series alloys may include Cr 20 Ni 35 Alloy, Cr 20 Ni 30 Alloy, Cr 15 Ni 60 Alloy, Cr 30 Ni 70 Alloy, Cr 20 Ni 80 Alloy, Cr 25 Ni 35 Alloy, or Cr 25 Ni 20 Alloys etc.

[0090] In some specific embodiments of the present invention, in step (1), the method of pre-treating the surface of the substrate includes immersing the substrate in an inorganic acid solution.

[0091] In some specific embodiments of the present invention, in step (1), the inorganic acid includes one or a combination of hydrochloric acid, nitric acid, phosphoric acid and sulfuric acid, and preferably includes hydrochloric acid and / or nitric acid.

[0092] In some specific embodiments of the present invention, in step (1), the concentration of the inorganic acid solution is 0.01 mol / L to 0.1 mol / L.

[0093] In some specific embodiments of the present invention, in step (1), the soaking time is 10 min to 150 min, preferably 20 min to 120 min.

[0094] In some specific embodiments of the present invention, in step (1), the method of pre-treating the substrate surface further includes: washing and drying the substrate after soaking in the inorganic acid solution. This process is for cleaning the inorganic acid remaining on the substrate surface and for keeping the substrate surface dry. The drying can be vacuum drying, with a drying vacuum degree of 100 to 400 Pa, a drying temperature of 40 to 90° C. (preferably 40 to 80° C.), and a drying time of 0.1 to 5 hours (preferably 1 to 5 hours).

[0095] In some specific embodiments of the present invention, in step (2), the loading method of the first coating material includes one or a combination of liquid phase brushing, atomization spraying, physical vapor deposition, chemical vapor deposition and immersion, preferably atomization spraying.

[0096] In some specific embodiments of the present invention, in step (2), the loading amount of the first coating on the pretreated substrate surface is 74 to 370 g / m 2 , preferably 74 to 300 g / m 2 .

[0097] In some specific embodiments of the present invention, in step (2), the atmosphere stabilization treatment includes: using a mixture of nitrogen and hydrogen as a stabilization treatment atmosphere, using programmed temperature increase in the stabilization treatment atmosphere to heat the substrate loaded with the first coating material to a stabilization treatment temperature, and after reaching the stabilization treatment temperature, maintaining the temperature at a constant level for a period of time to complete the atmosphere stabilization treatment.

[0098] In some specific embodiments of the present invention, in the atmosphere stabilization treatment in step (2), the volume concentration of hydrogen in the mixture of nitrogen and hydrogen is 10 to 40%, preferably 10 to 30%.

[0099] In some specific embodiments of the present invention, in the atmosphere stabilization treatment in step (2), the flow rate of the mixed gas of nitrogen and hydrogen is 10 to 100 mL / min, preferably 30 to 70 mL / min.

[0100] In some specific embodiments of the present invention, in the atmosphere stabilization treatment in step (2), the heating rate of the programmed temperature is 5 to 15° C. / min, preferably 5 to 10° C. / min.

[0101] In some specific embodiments of the present invention, in the atmosphere stabilization treatment in step (2), the stabilization treatment temperature is 500-750°C, preferably 500-650°C.

[0102] In some specific embodiments of the present invention, during the atmosphere stabilization treatment in step (2), the constant temperature is maintained for 3 to 7 hours.

[0103] In existing coating technologies, solvent coating is often used to introduce catalytically active components. During the coating process, the catalytically active components will agglomerate with each other, resulting in the catalytic coking inhibition performance of the prepared coating being limited. In addition, during long-term use, due to repeated high-temperature thermal shock and high-temperature migration of elements, the service life of the existing coating is short, and the catalytically active elements are easily lost, resulting in the coating's coking inhibition performance being difficult to maintain at a high level.

[0104] In the coating preparation method of the present invention, acid washing the substrate surface creates defects on the substrate surface, thereby strengthening the bonding between the first coating material and the substrate surface. After the first coating material of the present invention is applied to the substrate surface, the catalytically active components are evenly dispersed on the substrate surface. Combined with the atmosphere stabilization treatment, the catalytically active components are reduced, while the complexing agent decomposes under high temperature, facilitating the high-temperature thermal penetration of subsequent elements.

[0105] In some specific embodiments of the present invention, in step (3), the loading method of the second coating material includes liquid phase painting or solid powder embedding.

[0106] In some specific embodiments of the present invention, in step (3), the solid powder embedding specifically includes: embedding the substrate with the first coating in a container containing a second coating material, and filling the space between the substrate with the first coating and the container with the second coating material to obtain a substrate loaded with the second coating material. The volume filling amount of the second coating material can be 90% to 100% of the total volume of the container. The position of the substrate with the first coating in the container can be at the center of the container or at any position below it. The container is an inert container, preferably a high-temperature resistant infiltration box.

[0107] In some specific embodiments of the present invention, in step (3), the high-temperature thermal co-infiltration includes: performing a high-temperature heat treatment on the substrate loaded with the second coating material. Preferably, the high-temperature thermal co-infiltration specifically includes: heating the substrate loaded with the second coating material to 850-1200° C. using a programmed temperature increase, and then maintaining the temperature for a period of time to complete the high-temperature thermal co-infiltration.

[0108] In some specific embodiments of the present invention, the high-temperature thermal co-diffusion in step (3) is carried out in a protective atmosphere, and the protective atmosphere includes nitrogen and / or argon, etc.

[0109] In some specific embodiments of the present invention, during the high-temperature thermal co-infiltration in step (3), the substrate loaded with the second coating material is heated to 850-1100°C, preferably 950-1100°C.

[0110] In some specific embodiments of the present invention, in the high-temperature thermal co-infiltration of step (3), the heating rate of the programmed temperature is 1 to 10° C. / min.

[0111] In some specific embodiments of the present invention, during the high-temperature thermal co-infiltration in step (3), the constant temperature is maintained for 4 to 9 hours.

[0112] In some specific embodiments of the present invention, step (3) further comprises: grinding and polishing after high-temperature thermal co-infiltration to obtain the cracking furnace tube coating.

[0113] In order to improve the stability of the catalytically active components in a high-temperature environment and inhibit the element migration and agglomeration of the catalytically active components under high temperature, the present invention further loads a second coating material on the surface of the first coating, so that the alumina filler in the second coating material fills the gaps between the catalytically active components, and through high-temperature thermal co-infiltration, the catalytically active components are fixed and blocked by the inert protective component under high temperature, and the agglomeration and migration phenomenon is effectively controlled. On the other hand, the introduction of the inert protective component will also enhance the overall mechanical properties of the coating of the present invention, so that the coating obtains stronger thermal corrosion resistance and sintering resistance. In the coking inhibition performance evaluation test, the coating of the present invention can increase the coking inhibition amount by 34% compared with the inert coating prepared by the traditional method; compared with the catalytic coating prepared by the traditional method, the coking inhibition amount can be increased by up to 23%; and after repeated coking inhibition evaluation tests, the coking inhibition performance of the coating of the present invention decreases less, and after use, the catalytically active components in the coating of the present invention can still maintain a high degree of dispersion.

[0114] A third aspect of the present invention provides a cracking furnace tube coating, which is prepared by the above-mentioned method for preparing the cracking furnace tube coating.

[0115] In some specific embodiments of the present invention, the thickness of the cracking furnace tube coating is 20 to 300 μm.

[0116] The cracking furnace tube coating provided by the present invention can be applied to the production of olefins, especially ethylene.

[0117] Existing cracking furnace tube coating technology uses physical or chemical methods to prepare one or more protective coatings on the inner surface of the cracking furnace tube. These coatings can not only play a shielding role on the catalytic coking active elements such as iron and nickel in the furnace tube substrate, but also reduce the corrosion effect of carburization on the cracking furnace tube during ethylene production. By further introducing catalytic active elements such as K, Ca or rare earth into the coating, the coating can obtain a catalytic conversion function for free radical coking and condensation coking. Although the existing coating technology has a relatively good shielding and catalytic conversion effect on catalytic coking, free radical coking and condensation coking, the dispersion of the catalytic active elements contained in these coating materials is often low, so that the inhibitory effect of the coating on coke in different areas during application is not the same, resulting in uneven local heating of the coating, resulting in a decrease in the overall mechanical properties of the coating and the service life of the cracking furnace tube. On the other hand, under the action of continuous thermal shock, the catalytic active elements contained in the existing coating technology will migrate and fall off, resulting in a decrease in the overall coking inhibition effect of the coating.

[0118] The ethylene cracking furnace tube coating prepared from the coating material composition of the present invention is a ceramic coating. While the ceramic coating has the function of high-temperature protection for the substrate, it also has the function of catalytic gasification conversion of coke generated during the hydrocarbon cracking process. The ceramic coating has excellent mechanical properties, thermal corrosion resistance and sintering resistance. The catalytically active elements contained in the coating have a high degree of dispersion, so that the coating has an excellent inhibitory effect on coke during application. At the same time, the catalytically active elements contained in the coating are relatively stable. During repeated use, the overall element migration phenomenon in the coating is less, and the element loss is low. Therefore, the ceramic coating can effectively inhibit the coking of the cracking furnace tube and increase the service life of the cracking furnace tube.

[0119] The technical solutions of the present invention are specifically described below through examples and comparative examples, but the present invention is not limited to these examples and can of course be implemented with various modifications within the scope of the gist of the present invention.

[0120] The raw materials used in the embodiments and comparative examples include:

[0121] Acetone: purchased from Sinopharm Reagent, AR (Shanghai test), ≥99.5%;

[0122] Disodium EDTA: purchased from aladdin reagent, 98%;

[0123] Tris(hydroxymethyl)aminomethane: purchased from aladdin reagent, ACS, ≥99.8%;

[0124] Disodium nitrilotriacetate: purchased from aladdin reagent, >98.0%;

[0125] Cerium nitrate, potassium nitrate, calcium nitrate, and manganese chloride: purchased from Sinopharm Reagent, AR, 99.0%;

[0126] Potassium sodium tartrate: purchased from aladdin reagent, AR, 99.0%;

[0127] Sodium citrate: purchased from aladdin reagent, AR, 99.0%;

[0128] Ammonium acetate: purchased from Sinopharm Reagent, AR (Shanghai test), ≥98.0%;

[0129] Concentrated hydrochloric acid: purchased from Sinopharm Reagent, concentration ≥98%;

[0130] Chromium powder, silicon powder, and aluminum powder were purchased from Sinopharm Reagent, with a particle size of 200 mesh;

[0131] Chromium fluoride and sodium fluoride were purchased from Sinopharm Reagent, AR;

[0132] Zirconium chloride and ammonium chloride: purchased from Sinopharm Reagent, AR (Shanghai test), ≥99.0%;

[0133] Alumina: purchased from Sinopharm Reagent, particle size is 200 mesh.

[0134] The analysis and testing methods used in the examples and comparative examples include:

[0135] 1. The coating material's surface morphology and elemental analysis were characterized using a Hitachi SU8010 cold-field emission scanning electron microscope (SEM) at a scanning voltage of 25 kV. To better characterize the distribution of catalytically active elements within the coating bulk, the coating samples were first cut and the coating cross-section thickness was observed using an electron microscope. Based on the coating thickness, single-point EDS analysis was performed perpendicularly from the coating's outer surface to generate a plot of the catalytically active element content along the vertical direction of the coating.

[0136] 2. The coating coking inhibition performance test adopts a hanging piece evaluation device. The device hangs the coating sample in a tubular reactor, and simulates the steam cracking reaction conditions under high temperature conditions by passing water vapor and hydrocarbon raw gas into the tubular reactor. Naphtha is used as the cracking raw gas to test the coating hanging piece's coking inhibition performance. The reaction conditions are: the mass ratio of naphtha to deionized water is 2:1, the naphtha flow rate is 8mL / min, and the deionized water flow rate is 3mL / min. After the two are mixed and preheated to 360℃, they are passed into the tubular reactor for cracking reaction. The cracking reaction temperature is maintained at 840℃, the reaction pressure is 30kPa, and the cracking reaction time is 5h. After the reaction is completed, the coating hanging piece is taken out, and the total weight W of the coating hanging piece after coking is weighed using an electronic balance. 总重量 , after deducting the weight of the coating coupon before the evaluation test W0 through formula (1), the coking amount of the coating coupon W is obtained.焦炭 .W 焦炭 =W 总重量 -W0 (1)

[0137] In order to better express the catalytic conversion effect of the coating on coke, the coking inhibition rate is used to illustrate the coking inhibition performance of the coating. The calculation formula of the coking inhibition rate is shown in formula (2): S = (W 参比 -W 焦炭 ) / W 参比 ×100% (2)

[0138] Among them, S is the coking inhibition rate, W 焦炭 is the amount of coking on the coating coupon, W 参比 is the coking amount of the reference coupon (i.e., the coking amount of the uncoated coupon).

[0139] 3. The coating stability performance test was conducted using a coupon evaluation device. Multiple cycles were used for evaluation, with a total of six cycles and a single evaluation duration of 12 hours. The reaction conditions were: a naphtha to deionized water mass ratio of 2.5:1, a naphtha flow rate of 11 mL / min, and a deionized water flow rate of 3 mL / min. The mixture was preheated to 360°C and then introduced into a tubular reactor for a cracking reaction. The cracking reaction temperature was maintained at 850°C and the reaction pressure was 30 kPa. After the reaction, the coating coupons were removed, weighed using an electronic balance, and the coking inhibition rate (Sn) of the coating was calculated (n represents the number of test cycles, where n = 1, 2, 3, 4, 5, or 6). After the calculation, the coked coating coupons were placed in a muffle furnace and calcined in air at 900°C for 6 hours. After the furnace temperature dropped to room temperature, the coating coupons were removed and re-weighed after the coke was removed. After recording is completed, the coating sample is hung back into the evaluation device and the next evaluation cycle test is carried out under the same reaction conditions.

[0140] The composition of the raw material naphtha used in the above-mentioned coating coking inhibition performance test and coating stability performance test is shown in Table 1.

[0141] Table 1

[0142] Preparation of blank samples (i.e., uncoated samples)

[0143] Take Cr 25 Ni 35 The alloy was used as the substrate and was first processed into several blank samples with a size of 30 mm × 15 mm × 5 mm. The samples were polished with sandpaper to remove the oxide layer on the surface of the samples. The surfaces of the samples were then degreased and cleaned with acetone. Then, ultrasonic cleaning was performed and the samples were placed in a vacuum drying oven for drying. After drying, blank samples were obtained and recorded as KB-1.

[0144] Preparation of the first coating material A

[0145] Based on the total mass of the first coating material A being 100%, it is composed of the following components: 29% of cerium nitrate, 6% of disodium edetate, 10% of tris(hydroxymethyl)aminomethane, and 55% of deionized water.

[0146] The preparation method of the first coating material A comprises the following steps:

[0147] (a) cerium nitrate, tris(hydroxymethyl)aminomethane) and a portion of deionized water were mixed and stirred at a constant temperature of 30° C. and a stirring speed of 400 rpm to form a mixed system;

[0148] (b) mixing disodium edetate with another portion of deionized water to obtain a disodium edetate solution having a concentration of 0.5 mol / L;

[0149] (c) adding the disodium ethylenediaminetetraacetic acid solution obtained in step (b) dropwise to the mixed system obtained in step (a) at a dropping rate of 3 mL / min; during the dropping process, the system was continuously stirred at a constant temperature of 40° C. and a stirring speed of 300 rpm; and after the dropping was completed, stirring was continued for 60 min to obtain a first coating material A.

[0150] The pH value of the first coating material A is 8.

[0151] Preparation of the first coating material B

[0152] Based on the total mass of the first coating material B being 100%, it is composed of the following components: 19% of lanthanum nitrate, 5% of disodium nitrilotriacetate, 7% of sodium citrate, and 69% of deionized water.

[0153] The preparation method of the first coating material B comprises the following steps:

[0154] (a) mixing lanthanum nitrate, sodium citrate, and a portion of deionized water, and stirring at a constant temperature of 40° C. and a stirring speed of 400 rpm to form a mixed system;

[0155] (b) mixing disodium nitrilotriacetate with another portion of deionized water to obtain a disodium nitrilotriacetate solution having a concentration of 0.4 mol / L;

[0156] (c) adding the disodium nitrilotriacetate solution obtained in step (b) dropwise to the mixed system obtained in step (a) at a dropping rate of 2.5 mL / min; during the dropping process, the system was continuously stirred at a constant temperature of 40° C. and a stirring speed of 300 rpm; and after the dropping was completed, stirring was continued for 60 min to obtain a first coating material B.

[0157] The pH value of the first coating material B is 8.

[0158] Preparation of the first coating material C

[0159] Based on the total mass of the first coating material C being 100%, it is composed of the following components: 17% of cerium nitrate, 6% of potassium nitrate, 5% of disodium nitrilotriacetate, 7% of tris(hydroxymethyl)aminomethane, and 65% of deionized water.

[0160] The preparation method of the first coating material C comprises the following steps:

[0161] (a) cerium nitrate, potassium nitrate, tris(hydroxymethyl)aminomethane) and a portion of deionized water were mixed and stirred at a constant temperature of 40° C. and a stirring speed of 300 rpm to form a mixed system;

[0162] (b) mixing disodium nitrilotriacetate with another portion of deionized water to obtain a disodium nitrilotriacetate solution having a concentration of 0.4 mol / L;

[0163] (c) adding the disodium nitrilotriacetate solution obtained in step (b) dropwise to the mixed system obtained in step (a) at a dropping rate of 1.5 mL / min; during the dropping process, the system was continuously stirred at a constant temperature of 40° C. and a stirring speed of 300 rpm; and after the dropping was completed, stirring was continued for 75 min to obtain a first coating material C.

[0164] The pH value of the first coating material C is 7.

[0165] Preparation of the first coating material D

[0166] Based on the total mass of the first coating material D being 100%, it is composed of the following components: 10% of cerium nitrate, 2% of manganese chloride, 10% of potassium sodium tartrate, 15% of ammonium acetate and 63% of deionized water.

[0167] The preparation method of the first coating material D comprises the following steps:

[0168] (a) cerium nitrate, manganese chloride, ammonium acetate, and a portion of deionized water were mixed and stirred at a constant temperature of 20° C. and a stirring speed of 300 rpm to form a mixed system;

[0169] (b) mixing potassium sodium tartrate with another portion of deionized water to obtain a potassium sodium tartrate solution having a concentration of 1 mol / L;

[0170] (c) The potassium sodium tartrate solution obtained in step (b) was added dropwise to the mixed system obtained in step (a) at a dropping rate of 1.5 mL / min. During the dropping process, the system was continuously stirred at a constant temperature of 40° C. and a stirring speed of 300 rpm. After the dropwise addition was completed, stirring was continued for 75 min to obtain a first coating material D.

[0171] The pH value of the first coating material D is 8.

[0172] Preparation of the first coating material E

[0173] Based on the total mass of the first coating material E being 100%, it consists of the following components: 10% of cerium nitrate, 5% of calcium nitrate, 5% of disodium nitrilotriacetate, 10% of sodium citrate and 70% of deionized water.

[0174] The preparation method of the first coating material E comprises the following steps:

[0175] (a) cerium nitrate, calcium nitrate, sodium citrate, and a portion of deionized water were mixed and stirred at a constant temperature of 40° C. and a stirring speed of 300 rpm to form a mixed system;

[0176] (b) mixing disodium nitrilotriacetate with another portion of deionized water to obtain a disodium nitrilotriacetate solution having a concentration of 0.4 mol / L;

[0177] (c) adding the disodium nitrilotriacetate solution obtained in step (b) dropwise to the mixed system obtained in step (a) at a dropping rate of 3 mL / min; during the dropping process, the system was continuously stirred at a constant temperature of 40° C. and a stirring speed of 300 rpm; and after the dropping was completed, stirring was continued for 75 min to obtain a first coating material E.

[0178] The pH value of the first coating material E is 7.

[0179] Example 1

[0180] Take the KB-1 sample and perform acid pickling pretreatment on it. Use a dilute hydrochloric acid solution with a concentration of 0.1 mol / L. Take 300 mL of the dilute hydrochloric acid solution and place it in a glass beaker. Place the KB-1 sample in the dilute hydrochloric acid solution for soaking. After soaking for 30 minutes, take out the sample, wash the sample with water to clean the dilute hydrochloric acid solution remaining on the surface, and then place the sample in a vacuum drying oven. Set the drying temperature to 60°C and the vacuum degree to 400 Pa. After drying for 3 hours, take out the sample to obtain the pretreated sample.

[0181] The first coating material A was applied to the pretreated sample surface using an atomized spray method. The sample coated with the first coating material A was then stabilized using a mixture of nitrogen and hydrogen, with a hydrogen concentration of 20% by volume. The specific conditions for the stabilization treatment were: a set flow rate of 50 mL / min, a heating rate of 5°C / min to 650°C, and a constant temperature of 650°C for 3 hours to complete the stabilization treatment, forming the first coating A1. The sample was removed and weighed, revealing a loading of 0.149 g of the first coating A1.

[0182] The second coating material of this embodiment utilizes a solid particle mixture. Based on the total mass of the solid particle mixture as 100%, the second coating material comprises the following components: 25% chromium powder, 15% silicon powder, 1.3% chromium fluoride, 1.1% zirconium chloride, 1.5% ammonium chloride, and the balance alumina. The second coating material is prepared by placing the weighed components into a mixer, mixing for 10 hours, and then discharging the solid particle mixture to obtain the second coating material.

[0183] The second coating material is loaded onto the surface of the sample with the first coating A1 using a solid powder embedding method. The specific steps are as follows: embed the sample with the first coating A1 in an inert container containing the second coating material, with the embedded sample located at the center of the inert container, and the volume filling amount of the second coating material being 100% of the inert container. The sample and the second coating material are compacted, and the inert container is sealed.

[0184] The sealed inert container was placed in a muffle furnace for high-temperature heat treatment. Nitrogen was used as the protective atmosphere. The temperature in the muffle furnace was raised from room temperature to 700°C at a heating rate of 10°C / min, and then raised from 700°C to 1050°C at a heating rate of 5°C / min. The constant temperature was maintained for 7 hours to complete the high-temperature thermal co-infiltration.

[0185] After cooling, the second coating material powder was removed, and the sample was ground and polished to obtain a sample with a ceramic coating, which was recorded as SS-1.

[0186] Example 2

[0187] The first coating material B was applied to the pretreated sample surface provided in Example 1 using an atomized spray method. The sample loaded with the first coating material B was treated using the same atmosphere stabilization conditions as in Example 1 to form a first coating layer B1. After weighing, the loading amount of the first coating layer B1 was 0.121 g.

[0188] This embodiment uses the same second coating material and loading method as in Example 1. After being treated under the same high-temperature thermal co-infiltration conditions as in Example 1, the sample is ground and polished to obtain a sample with a ceramic coating, which is recorded as SS-2.

[0189] Example 3

[0190] The first coating material C was applied to the pretreated sample surface provided in Example 1 using an atomized spray method. The sample loaded with the first coating material C was treated using the same atmosphere stabilization conditions as in Example 1 to form a first coating layer C1. After weighing, the loading amount of the first coating layer C1 was 0.136 g.

[0191] This embodiment uses the same second coating material and loading method as in Example 1. After being treated under the same high-temperature thermal co-infiltration conditions as in Example 1, the sample is ground and polished to obtain a sample with a ceramic coating, which is recorded as SS-3.

[0192] Example 4

[0193] The first coating material D was applied to the pretreated sample surface provided in Example 1 using an atomized spray method. The sample loaded with the first coating material D was treated using the same atmosphere stabilization conditions as in Example 1 to form a first coating layer D1. After weighing, the loading amount of the first coating layer D1 was 0.117 g.

[0194] This embodiment uses the same second coating material and loading method as in Example 1. After being treated under the same high-temperature thermal co-infiltration conditions as in Example 1, the sample is ground and polished to obtain a sample with a ceramic coating, which is recorded as SS-4.

[0195] Example 5

[0196] The first coating material E was applied to the pretreated sample surface provided in Example 1 using a liquid-phase coating method. The sample loaded with the first coating material E was treated using the same atmosphere stabilization conditions as in Example 1 to form a first coating layer E1. After weighing, the loading amount of the first coating layer E1 was 0.127 g.

[0197] This embodiment uses the same second coating material and loading method as in Example 1. After being treated under the same high-temperature thermal co-infiltration conditions as in Example 1, the sample is ground and polished to obtain a sample with a ceramic coating, which is recorded as SS-5.

[0198] Example 6

[0199] Take the KB-1 sample and perform acid pickling pretreatment on it. Use a dilute hydrochloric acid solution with a concentration of 0.05 mol / L. Take 300 mL of the dilute hydrochloric acid solution and place it in a glass beaker. Place the KB-1 sample in the dilute hydrochloric acid solution for soaking. After soaking for 45 minutes, take out the sample, wash the sample with water to clean the dilute hydrochloric acid solution remaining on the surface, and then place the sample in a vacuum drying oven. Set the drying temperature to 70°C and the vacuum degree to 400 Pa. After drying for 2 hours, take out the sample to obtain the pretreated sample.

[0200] The pretreated sample surface was coated with the first coating material A using an atomized spray method. The sample coated with the first coating material A was then stabilized using a mixture of nitrogen and hydrogen, with a hydrogen concentration of 30% by volume. The specific conditions for the stabilization treatment were: a set flow rate of 50 mL / min, a heating rate of 5°C / min to 650°C, and a constant temperature of 650°C for 5 hours to complete the stabilization treatment, forming the first coating A2. The sample was removed and weighed, revealing a loading of 0.141 g of the first coating A2.

[0201] The second coating material of this embodiment utilizes a solid particle mixture. Based on the total mass of the solid particle mixture as 100%, the second coating material comprises the following components: 25% chromium powder, 15% silicon powder, 2.1% sodium fluoride, 1.7% ammonium chloride, and the balance alumina. The second coating material is prepared by placing the weighed components into a mixer, mixing for 10 hours, and then discharging the solid particle mixture to obtain the second coating material.

[0202] The second coating material is loaded onto the surface of the sample with the first coating A2 using a solid powder embedding method. The specific steps are as follows: embed the sample with the first coating A2 in an inert container containing the second coating material, with the embedded sample located at the center of the inert container and the volume filling amount of the second coating material being 100% of the inert container; compact the sample and the second coating material, and seal the inert container.

[0203] The sealed inert container was placed in a muffle furnace for high-temperature heat treatment. Argon was used as the protective atmosphere. The temperature in the muffle furnace was raised from room temperature to 600°C at a heating rate of 10°C / min, and then raised from 600°C to 950°C at a heating rate of 5°C / min. The constant temperature was maintained for 5 hours to complete the high-temperature thermal co-infiltration.

[0204] After cooling, the second coating material powder was removed, and the sample was ground and polished to obtain a sample with a ceramic coating, which was recorded as SS-6.

[0205] Example 7

[0206] The first coating material B was applied to the pretreated sample surface provided in Example 6 using an atomized spray method. The sample loaded with the first coating material B was treated using the same atmosphere stabilization conditions as in Example 6 to form a first coating layer B2. After weighing, the loading amount of the first coating layer B2 was 0.157 g.

[0207] This embodiment uses the same second coating material and loading method as Example 6. After being treated under the same high-temperature thermal co-infiltration conditions as Example 6, the sample is ground and polished to obtain a sample with a ceramic coating, which is recorded as SS-7.

[0208] Example 8

[0209] The first coating material C was applied to the pretreated sample surface provided in Example 6 using an atomized spray method. The sample loaded with the first coating material C was treated using the same atmosphere stabilization conditions as in Example 6 to form a first coating layer C2. After weighing, the loading amount of the first coating layer C2 was 0.144 g.

[0210] This embodiment uses the same second coating material and loading method as Example 6. After being treated under the same high-temperature thermal co-infiltration conditions as Example 6, the sample is ground and polished to obtain a sample with a ceramic coating, which is recorded as SS-8.

[0211] Example 9

[0212] The first coating material D was applied to the pretreated sample surface provided in Example 6 using a liquid-phase coating method. The sample loaded with the first coating material D was treated using the same atmosphere stabilization conditions as in Example 6 to form a first coating layer D2. The loading of the first coating layer D2 was found to be 0.126 g.

[0213] This embodiment uses the same second coating material and loading method as in Example 6. After being treated under the same high-temperature thermal co-infiltration conditions as in Example 6, the sample is ground and polished to obtain a sample with a ceramic coating, which is recorded as SS-9.

[0214] Example 10

[0215] The first coating material E was applied to the pretreated sample surface provided in Example 6 using an atomized spray method. The sample loaded with the first coating material E was treated using the same atmosphere stabilization conditions as in Example 6 to form a first coating layer E2. After weighing, the loading amount of the first coating layer E2 was 0.153 g.

[0216] This embodiment uses the same second coating material and loading method as Example 6. After being treated under the same high-temperature thermal co-infiltration conditions as Example 6, the sample is ground and polished to obtain a sample with a ceramic coating, which is recorded as SS-10.

[0217] Example 11

[0218] Take the KB-1 sample and perform acid pickling pretreatment on it. Use a dilute hydrochloric acid solution with a concentration of 0.01 mol / L. Take 300 mL of the dilute hydrochloric acid solution and place it in a glass beaker. Place the KB-1 sample in the dilute hydrochloric acid solution for soaking. After soaking for 100 minutes, take out the sample, wash the sample with water to clean the dilute hydrochloric acid solution remaining on the surface, and then place the sample in a vacuum drying oven. Set the drying temperature to 50°C and the vacuum degree to 400 Pa. After drying for 5 hours, take out the sample to obtain the pretreated sample.

[0219] The first coating material A was applied to the pretreated sample surface using an atomized spray method. The sample coated with the first coating material A was then stabilized using a mixture of nitrogen and hydrogen, with a hydrogen concentration of 10% by volume. The specific conditions for the stabilization treatment were: a set flow rate of 70 mL / min, a heating rate of 5°C / min to 650°C, and a constant temperature of 650°C for 6 hours to complete the stabilization treatment, forming the first coating A3. The sample was removed and weighed, revealing a loading of 0.122 g of the first coating A3.

[0220] The second coating material of this embodiment utilizes a solid particle mixture. Based on the total mass of the solid particle mixture as 100%, the second coating material comprises the following components: 25% chromium powder, 15% silicon powder, 10% aluminum powder, 1.3% sodium fluoride, 1.7% ammonium chloride, and the balance alumina. The second coating material is prepared by placing the weighed components into a mixer, mixing for 10 hours, and then discharging the solid particle mixture to obtain the second coating material.

[0221] The second coating material is loaded onto the surface of the sample with the first coating A3 using a solid powder embedding method. The specific steps are as follows: embed the sample with the first coating A3 in an inert container containing the second coating material, with the embedded sample located at the center of the inert container and the volume filling amount of the second coating material being 100% of the inert container; compact the sample and the second coating material, and seal the inert container.

[0222] The sealed inert container was placed in a muffle furnace for high-temperature heat treatment. Nitrogen was used as the protective atmosphere. The temperature in the muffle furnace was raised from room temperature to 700°C at a heating rate of 10°C / min, and then raised from 700°C to 1100°C at a heating rate of 5°C / min. The constant temperature was maintained for 5 hours to complete the high-temperature thermal co-infiltration.

[0223] After cooling, the second coating material powder was removed, and the sample was ground and polished to obtain a sample with a ceramic coating, which was recorded as SS-11.

[0224] Example 12

[0225] The first coating material B was applied to the pretreated sample surface provided in Example 11 using an atomized spray method. The sample loaded with the first coating material B was treated using the same atmosphere stabilization conditions as in Example 11 to form a first coating layer B3. The loading of the first coating layer B3 was determined to be 0.111 g.

[0226] This embodiment uses the same second coating material and loading method as Example 11. After being treated under the same high-temperature thermal co-infiltration conditions as Example 11, the sample is ground and polished to obtain a sample with a ceramic coating, which is recorded as SS-12.

[0227] Example 13

[0228] The first coating material C was applied to the pretreated sample surface provided in Example 11 using a liquid-phase coating method. The sample loaded with the first coating material C was treated using the same atmosphere stabilization conditions as in Example 11 to form a first coating layer C3. After weighing, the loading amount of the first coating layer C3 was 0.133 g.

[0229] This embodiment uses the same second coating material and loading method as Example 11. After being treated under the same high-temperature thermal co-infiltration conditions as Example 11, the sample is ground and polished to obtain a sample with a ceramic coating, which is recorded as SS-13.

[0230] Example 14

[0231] The first coating material D was applied to the pretreated sample surface provided in Example 11 using an atomized spray method. The sample loaded with the first coating material D was treated using the same atmosphere stabilization conditions as in Example 11 to form a first coating layer D3. After weighing, the loading amount of the first coating layer D3 was 0.130 g.

[0232] This embodiment uses the same second coating material and loading method as Example 11. After being treated under the same high-temperature thermal co-infiltration conditions as Example 11, the sample is ground and polished to obtain a sample with a ceramic coating, which is recorded as SS-14.

[0233] Example 15

[0234] The first coating material E was applied to the pretreated sample surface provided in Example 11 using an atomized spray method. The sample loaded with the first coating material E was treated using the same atmosphere stabilization conditions as in Example 11 to form a first coating layer E3. After weighing, the loading amount of the first coating layer E3 was 0.109 g.

[0235] This embodiment uses the same second coating material and loading method as Example 11. After being treated under the same high-temperature thermal co-infiltration conditions as Example 11, the sample is ground and polished to obtain a sample with a ceramic coating, which is recorded as SS-15.

[0236] Example 16

[0237] The acid pretreatment, first coating material A loading and atmosphere stabilization treatment conditions for the KB-1 sample in this example are the same as those in Example 1. The loading amount of the first coating A5 on the sample surface obtained through the above steps is 0.146 g.

[0238] The second coating material of this embodiment is a liquid slurry. Based on the total mass of the liquid slurry being 100%, the liquid slurry comprises the following components: 35% chromium powder, 17% silicon powder, 1.4% chromium fluoride, 1.1% zirconium chloride, 1.5% ammonium chloride, 24% aluminum oxide, and 20% ethanol. The second coating material is prepared by adding the weighed components to a beaker, stirring and mixing for 40 minutes, and then pouring out the liquid slurry to obtain the second coating material.

[0239] The second coating material was loaded on the surface of the sample with the first coating A5 by the liquid phase coating method, and the sample coated with the second coating material was placed in a 60°C drying oven. After drying for 1 hour, the sample was taken out and placed in a muffle furnace for high-temperature heat treatment. Nitrogen was used as the protective atmosphere and the temperature in the muffle furnace was raised from room temperature to 700°C at a heating rate of 10°C / min. Then, the temperature was raised from 700°C to 1050°C at a heating rate of 5°C / min. The constant temperature was maintained for 7 hours to complete the high-temperature thermal co-infiltration.

[0240] After cooling, the sample was ground and polished to obtain a sample with a ceramic coating, which was recorded as SS-16.

[0241] Comparative Example 1

[0242] This comparative example uses an inert coating material composed, based on the total mass of the inert coating material as 100%, of the following components: 21% chromium powder, 4% silicon powder, 0.4% chromium fluoride, 0.7% zirconium chloride, 3.2% ammonium chloride, and 70.7% aluminum oxide. The inert coating material is prepared by placing the weighed components into a mixer, mixing for 10 hours, and then discharging the solid particle mixture to obtain the inert coating material.

[0243] The inert coating material was loaded onto the surface of the KB-1 sample using a solid powder embedding method. The specific steps were as follows: the KB-1 sample was embedded in an inert container containing the inert coating material, with the embedded sample located at the center of the inert container. The volume of the inert coating material filled the inert container to 100%. The sample and the inert coating material were compacted, and the inert container was sealed.

[0244] The sealed inert container was placed in a muffle furnace for high-temperature heat treatment. Nitrogen was used as the protective atmosphere. The temperature in the muffle furnace was raised from room temperature to 700°C at a heating rate of 10°C / min, and then from 700°C to 950°C at a heating rate of 5°C / min. The constant temperature was maintained for 7 hours. After cooling, the inert coating material powder was removed, and the sample was polished to obtain a sample with an inert coating, which was recorded as DB-1.

[0245] Comparative Example 2

[0246] Take the KB-1 sample and prepare the coating on it according to the technical solution disclosed in CN114540749A. The specific preparation steps are as follows:

[0247] A KB-1 sample was placed in an inert container containing a barrier coating penetrant. The sample and barrier coating penetrant were compacted and sealed. The barrier coating penetrant, based on the total mass of the penetrant being 100%, consisted of the following components: 21% chromium powder, 4% silicon powder, 0.4% chromium fluoride, 0.7% zirconium oxide, 3.2% ammonium chloride, and 70.7% aluminum oxide. The sealed inert container was placed in a muffle furnace for chemical heat treatment. The temperature in the muffle furnace was programmed to increase from room temperature to 700°C at a rate of 10°C / min, then from 700°C to 950°C at a rate of 5°C / min. The temperature was maintained at this constant temperature for 7 hours. After cooling, the penetrant powder was removed, and the sample was polished to obtain a sample with a barrier coating.

[0248] The barrier-coated sample was embedded in an inert container containing a coke-clearing coating penetrant. The sample and the coke-clearing coating penetrant were compacted and the container was sealed. The coke-clearing coating penetrant, based on the total mass of 100%, consisted of the following components: 16.5% chromium powder, 4% silicon powder, 0.2% chromium fluoride, 4.5% lanthanum oxide, 3.2% ammonium chloride, and 71.6% aluminum oxide. The sealed inert container was placed in a muffle furnace for chemical heat treatment. The temperature in the muffle furnace was raised from room temperature to 700°C at a heating rate of 5°C / min, and then raised from 700°C to 850°C at a heating rate of 5°C / min. The temperature was maintained at a constant temperature for 7 hours. After cooling, the penetrant powder was removed. The sample was polished and brushed twice with a saturated calcium hydroxide solution, each time for 5 minutes. After drying, it was calcined in air at 600°C for 5 hours for stabilization treatment to obtain a sample with a self-cleaning coating, which was recorded as DB-2.

[0249] Comparative Example 3

[0250] Preparation of the first coating material F: Taking the total mass of the first coating material F as 100%, it is composed of the following components: 30% of cerium nitrate and 70% of anhydrous ethanol; the first coating material F is prepared by the following steps: cerium nitrate and anhydrous ethanol are mixed, and the mixture is stirred continuously for 60 minutes at a stirring speed of 400 rpm and a constant temperature of 40°C to obtain the first coating material F.

[0251] A first coating material F was applied to the surface of a KB-1 sample using a liquid-phase brushing method. The sample, coated with the first coating material F, was then stabilized using a mixture of nitrogen and hydrogen, with a hydrogen concentration of 20% by volume. The specific conditions for the stabilization treatment were: a set flow rate of 50 mL / min, a heating rate of 5°C / min to 650°C, and a constant temperature of 650°C for 3 hours. This completed the stabilization treatment, forming the first coating F1. The sample was removed and weighed, revealing a loading of 0.157 g for the first coating F1.

[0252] The second coating material of this embodiment utilizes a solid particle mixture. Based on the total mass of the solid particle mixture as 100%, the second coating material comprises the following components: 25% chromium powder, 15% silicon powder, 1.3% chromium fluoride, 1.1% zirconium chloride, 1.5% ammonium chloride, and the balance alumina. The second coating material is prepared by placing the weighed components into a mixer, mixing for 10 hours, and then discharging the solid particle mixture to obtain the second coating material.

[0253] The second coating material is loaded onto the surface of the sample with the first coating F1 using a solid powder embedding method. The specific steps are as follows: embed the sample with the first coating F1 in an inert container containing the second coating material, with the embedded sample located at the center of the inert container and the volume filling amount of the second coating material being 100% of the inert container. The sample and the second coating material are compacted, and the inert container is sealed.

[0254] The sealed inert container was placed in a muffle furnace for high-temperature heat treatment. Nitrogen was used as the protective atmosphere. The temperature in the muffle furnace was raised from room temperature to 700°C at a heating rate of 10°C / min, and then raised from 700°C to 950°C at a heating rate of 5°C / min. The constant temperature was maintained for 7 hours to complete the high-temperature thermal co-infiltration.

[0255] After cooling, the second coating material powder was removed, and the sample was ground and polished to obtain a sample with a ceramic coating, which was recorded as DB-3.

[0256] Comparative Example 4

[0257] The KB-1 sample was pretreated using the same acid pretreatment conditions as in Example 1.

[0258] Preparation of the first coating material G: Taking the total mass of the first coating material G as 100%, it is composed of the following components: 45% of cerium nitrate and 55% of deionized water; the first coating material G is prepared by the following steps: mixing cerium nitrate and deionized water, and continuously stirring for 60 minutes at a stirring speed of 400 rpm and a constant temperature of 40°C to obtain the first coating material G.

[0259] The first coating material G was applied to the pretreated sample surface using an atomized spray method. The sample coated with the first coating material G was then stabilized using a mixture of nitrogen and hydrogen, with a hydrogen concentration of 20% by volume. The specific conditions for the stabilization treatment were: a set flow rate of 50 mL / min, a heating rate of 5°C / min to 650°C, and a constant temperature of 650°C for 3 hours to complete the stabilization treatment, forming the first coating layer G1. The sample was removed and weighed, revealing a loading of 0.181 g of the first coating layer G1.

[0260] The second coating material of this embodiment utilizes a solid particle mixture. Based on the total mass of the solid particle mixture as 100%, the second coating material comprises the following components: 25% chromium powder, 15% silicon powder, 1.3% chromium fluoride, 1.1% zirconium chloride, 1.5% ammonium chloride, and the balance alumina. The second coating material is prepared by placing the weighed components into a mixer, mixing for 10 hours, and then discharging the solid particle mixture to obtain the second coating material.

[0261] The second coating material is loaded onto the surface of the sample with the first coating G1 using a solid powder embedding method. The specific steps are as follows: embed the sample with the first coating G1 in an inert container containing the second coating material, with the embedded sample located at the center of the inert container, and the volume filling amount of the second coating material being 100% of the inert container. The sample and the second coating material are compacted, and the inert container is sealed.

[0262] The sealed inert container was placed in a muffle furnace for high-temperature heat treatment. Nitrogen was used as the protective atmosphere. The temperature in the muffle furnace was raised from room temperature to 700°C at a heating rate of 10°C / min, and then raised from 700°C to 1050°C at a heating rate of 5°C / min. The constant temperature was maintained for 7 hours to complete the high-temperature thermal co-infiltration.

[0263] After cooling, the second coating material powder was removed, and the sample was ground and polished to obtain a sample with a ceramic coating, which was recorded as DB-4.

[0264] The analysis and test results of the above embodiments and comparative examples are described below.

[0265] 1. Surface morphology and elemental analysis of coating materials

[0266] The SEM images and EDS elemental characterization results of the coatings shown in Figures 1, 2, 3, and 4 demonstrate that the catalytically active components in the ceramic coatings prepared according to the present invention are uniformly dispersed on the surface of the coating, with a high degree of dispersion. Sections of the ceramic coatings were cut and elemental distribution analysis was performed on the cross-sections. The results demonstrate that the catalytically active components are not only uniformly distributed on the surface but also maintain a high degree of dispersion within the bulk of the coating, resulting in a relatively uniform overall distribution of the catalytically active components.

[0267] 2. Coating anti-coking performance

[0268] The coking amounts and coking inhibition rates of the coatings prepared in Examples 1 to 16 and Comparative Examples 1 to 4 under the same coking inhibition performance evaluation conditions are shown in Table 2.

[0269] Table 2

[0270] It can be seen from the data in Table 2 that the ceramic coating prepared by the present invention has a good catalytic conversion function for coke. Taking the SS-1 data as an example, the coking amount of the SS-1 ceramic coating is significantly reduced compared with the coking amount of the KB-1 blank sample, and the coking inhibition rate of SS-1 can reach up to 90.06%. Compared with the inert coating of DB-1, the coking inhibition rate of SS-1 is significantly improved. Compared with the existing DB-2 catalytic coating, the coking inhibition rate of SS-1 can be increased by up to 23%. Combined with the scanning electron microscopy characterization results, it can be seen that the catalytically active components in the ceramic coating prepared by the present invention can maintain a high degree of dispersion, the catalytically active components can give full play to their own catalytic effect, and the overall catalytic conversion efficiency of the ceramic coating for coke is high, which ultimately makes the ceramic coating have more excellent coking inhibition performance.

[0271] 3. Coating stability

[0272] By recycling the coating for multiple times and evaluating its coking inhibition performance, a trend diagram of the coking inhibition rate of the coatings prepared in Example 1, Example 6, Example 11 and Comparative Example 2 as a inverse of the use cycle period is obtained, as shown in Figure 5. As can be seen from Figure 5, the coking inhibition performance of the ceramic coating prepared by the present invention remains essentially unchanged after repeated use. This indicates that the catalytically active components in the ceramic coating of the present invention have higher stability under high temperature conditions, and their element migration and agglomeration effects under high temperature are relatively weak. The inert protective components can fill the gaps between the catalytically active components through high-temperature thermal co-infiltration, so that the catalytically active components are fixed and blocked by the inert protective components under high temperature, and the agglomeration and migration phenomenon is effectively controlled.

[0273] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the scope of protection of the present invention.

Claims

1. A cracking furnace tube coating material composition, comprising: a first coating material and a second coating material; Wherein, based on the total mass of the first coating material being 100%, it comprises the following components: 10-40% of a catalytically active component, 2-30% of a complexing agent, 5-20% of a buffer and 40-70% of a first dispersant; the catalytically active component comprises one or a combination of compounds of alkali metal elements, compounds of alkaline earth metal elements, compounds of rare earth metal elements and compounds of transition metal elements; The second coating material is a liquid slurry or a solid particle mixture; based on the total mass of the liquid slurry as 100%, it includes the following components: 10-65% of an inert protective component, 0.1-3.0% of a flux, 1.0-5.0% of an activator, 20-80% of a filler and the remainder of a second dispersant; based on the total mass of the solid particle mixture as 100%, it includes the following components: 15-60% of an inert protective component, 0.1-2.5% of a flux, 1.0-6.0% of an activator and the remainder of a filler.

2. The coating material composition according to claim 1, wherein Taking the total mass of the first coating material as 100%, The invention comprises the following components: 10-29% of catalytic active component, 5-15% of complexing agent, 5-15% of buffering agent and 40-70% of first dispersant.

3. The coating material composition according to claim 1, wherein: Among the components of the first coating material, the alkali metal elements include one or more combinations of Li, Na and K; the alkaline earth metal elements include one or more combinations of Mg, Ca, Sr and Ba; the rare earth metal elements include one or more combinations of La, Ce, Pr, Nd and Y; the transition metal elements include one or more combinations of Co, Mn, Mo, Cu, Zn, V, Ti, Cr, W, Rh and Hf.

4. The coating material composition according to claim 1, wherein In the components of the first coating material, the complexing agent includes one or a combination of disodium nitrilotriacetate, disodium ethylenediaminetetraacetate, dithizone, 8-hydroxyquinoline, o-phenanthroline, potassium sodium tartrate and polyphosphate.

5. The coating material composition according to claim 1, wherein: In the components of the first coating material, the buffer includes one or a combination of ammonium acetate, tris(hydroxymethyl)aminomethane and citrate.

6. The coating material composition according to claim 1, wherein: Among the components of the first coating material, the first dispersant includes one or a combination of deionized water, ethanol, ethylene glycol, acetone and chloroform.

7. The coating material composition according to claim 1, wherein: The first coating material is prepared by at least the following steps: (a) mixing the catalytically active component, the buffer and a portion of the first dispersant, and stirring to form a mixed system; (b) mixing the complexing agent and another portion of the first dispersant to obtain a complexing agent solution; (c) adding the complexing agent solution obtained in step (b) to the mixed system obtained in step (a) under stirring conditions, and continuing to stir for a period of time after the addition is completed to obtain the first coating material.

8. The coating material composition according to claim 1, wherein Taking the total mass of the liquid slurry as 100%, it includes the following components: 15-60% of inert protective component, 0.1-2.5% of flux, 1.0-2.0% of activator, 24-70% of filler and the balance of second dispersant.

9. The coating material composition according to claim 1, wherein: Taking the total mass of the solid particle mixture as 100%, it comprises the following components: Inert protective component 24-58%, flux 0.1-2.5%, activator 1.1-4.0% and filler balance.

10. The coating material composition according to claim 1, wherein: In the components of the second coating material, the inert protective component includes one or a combination of chromium, silicon and aluminum.

11. The coating material composition according to claim 1, wherein: In the components of the second coating material, the flux includes one or a combination of chromium fluoride, sodium fluoride, zirconium chloride and potassium fluoride.

12. The coating material composition according to claim 1, wherein: In the components of the second coating material, the activator includes one or a combination of ammonium chloride, ammonium fluoride and ammonium sulfate.

13. The coating material composition according to claim 1, wherein: In the composition of the second coating material, the filler includes aluminum oxide.

14. The coating material composition according to claim 1, wherein: Among the components of the second coating material, the second dispersant includes one or a combination of deionized water, ethanol, ethylene glycol, acetone and chloroform.

15. A method for preparing a cracking furnace tube coating, the method using the cracking furnace tube coating material composition according to claim 1 to form a coating, the method comprising the following steps: (1) Pre-treating the substrate surface; (2) loading a first coating material on the surface of the pretreated substrate, and then performing an atmosphere stabilization treatment to form a first coating; (3) The second coating material is loaded on the surface of the first coating, and then high-temperature thermal infiltration is performed to obtain the cracking furnace tube coating.

16. The preparation method according to claim 15, wherein: In step (1), the method of pre-treating the surface of the substrate includes immersing the substrate in an inorganic acid solution.

17. The preparation method according to claim 15, wherein: In step (2), the loading amount of the first coating on the pretreated substrate surface is 74 to 370 g / m 2 .

18. The preparation method according to claim 15, wherein: In step (2), the atmosphere stabilization treatment includes: using a mixture of nitrogen and hydrogen as a stabilization treatment atmosphere, in the stabilization treatment atmosphere, using programmed temperature increase to heat the substrate carrying the first coating material to a stabilization treatment temperature, and after reaching the stabilization treatment temperature, maintaining the temperature at a constant level for a period of time to complete the atmosphere stabilization treatment; the stabilization treatment temperature is 500 to 750°C, and the constant temperature is maintained for 3 to 7 hours.

19. The preparation method according to claim 15, wherein: In step (3), in step (3), the high-temperature thermal co-infiltration includes: performing high-temperature heat treatment on the substrate loaded with the second coating material; the temperature of the high-temperature heat treatment is 850-1200°C, and the constant temperature is maintained for 4-9 hours; the high-temperature thermal co-infiltration is carried out in a protective atmosphere, and the protective atmosphere includes nitrogen and / or argon.

20. A cracking furnace tube coating, which is prepared by the method for preparing a cracking furnace tube coating according to claim 15.

21. The cracking furnace tube coating according to claim 20, wherein: The thickness of the cracking furnace tube coating is 20 to 300 μm.

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