A sulfur-resistant and erosion-resistant metal honeycomb VOCs catalyst and its preparation method

Abstract

This invention discloses a sulfur-resistant and erosion-resistant metal honeycomb VOCs catalyst and its preparation. The catalyst comprises a metal support, an alumina layer, a titanium oxide mixture, and an active component. The alumina layer, titanium oxide mixture, and active component are all attached to the metal support. The metal support is a metal honeycomb support. The titanium oxide mixture comprises titanium monoxide, titanium dioxide, and titanium trioxide, which are mixed to form a layered structure. The active component is a mixture of reduced noble metal elements and transition metal oxides. This invention utilizes alumina and titanium oxide materials to create a multi-material layered structure on the metal support, thereby enabling the active component to obtain more stable attachment sites, enhancing the catalyst's catalytic stability and maintaining its catalytic efficiency.

Description

Technical Field

[0001] This invention relates to the field of metal honeycomb VOCs catalysts and their preparation, specifically a sulfur-resistant and erosion-resistant metal honeycomb VOCs catalyst and its preparation method. Background Technology

[0002] Volatile organic compounds (VOCs) are a class of organic compounds with a boiling point below 260°C at normal pressure or a saturated vapor pressure above 70.91 Pa at room temperature. When VOCs are emitted into the atmosphere, they react with nitrogen oxides (NOx) emitted from the combustion of fossil fuels under sunlight. X SO X The formation of aerosol particles from smog can severely damage the human immune system, and even cause cancer, leukemia, nasopharyngeal carcinoma or other malignant tumors, posing a great threat to human health.

[0003] Catalytic combustion, with the aid of a catalyst, enables the complete combustion of organic waste gas at a relatively low ignition temperature, oxidizing VOCs into CO2 and H2O and releasing a large amount of heat to achieve self-heating of the reaction. Simultaneously, heat recovery is performed, maximizing energy savings throughout the process. Catalytic combustion boasts advantages such as wide applicability, low ignition temperature, low energy consumption, high efficiency, and no secondary pollution. The core of this technology is a superior catalyst.

[0004] Existing VOCs catalysts are typically used in low-space-velocity, low-scour exhaust gas environments, where the catalyst coating is less affected by exhaust gas scour and can maintain excellent catalyst performance. However, when applied to high-space-velocity, high-scour exhaust gas environments, the catalyst coating will peel off to some extent, leading to a decrease in catalyst performance. Compared to ceramic honeycomb carriers, metal honeycomb carriers have good heat and mass transfer functions and have been widely used. However, the adhesion and durability of the catalyst coating on the metal carrier are more severely affected, making it impossible to continuously and effectively guarantee the purification effect and long service life requirements of the catalyst. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing metal honeycomb VOCs catalysts, which have low catalytic efficiency and poor catalytic stability when catalyzing volatile organic compounds. This invention provides a sulfur-resistant and erosion-resistant metal honeycomb VOCs catalyst and its preparation method. By using alumina and titanium oxide materials, a multi-material layered structure is constructed on a metal support, thereby enabling the active components to obtain more stable attachment sites, thus enhancing the stability of the catalyst and maintaining its catalytic efficiency.

[0006] The objective of this invention is mainly achieved through the following technical solutions:

[0007] A sulfur-resistant and erosion-resistant metal honeycomb VOCs catalyst includes a metal support, on which an alumina layer and a mixed layer are sequentially coated. The mixed layer is composed of a titanium oxide mixture, an active component, and a binder.

[0008] The metal carrier is a metal honeycomb carrier;

[0009] The mass percentage of the alumina layer is 10.000 wt% to 30.000 wt% of the total load of the metal carrier.

[0010] The titanium oxide mixture comprises titanium monoxide, titanium dioxide, and titanium trioxide, wherein the titanium monoxide, titanium dioxide, and titanium trioxide are mixed to form a layered structure; the titanium oxide mixture accounts for 44.800 wt% to 80.973 wt% of the total loading of the metal carrier;

[0011] The active component is a mixture of reduced noble metals and transition metal oxides. The proportion of noble metals is 0.007 wt% to 1.800 wt% of the total loading of the metal carrier, and the proportion of transition metal oxides is 3.510 wt% to 17.100 wt% of the total loading.

[0012] The binder accounts for 3.500 wt% to 13.500 wt% of the total load of the metal carrier.

[0013] Currently, the treatment of volatile organic compounds mainly relies on the catalytic decomposition of volatile organic compounds by catalysts to obtain relatively safe decomposition products. The catalysts used in existing technologies are usually ceramic supports, but ceramic supports have weak heat and mass transfer functions, so they cannot achieve good catalytic performance. Metal supports have better heat and mass transfer functions, but they have the problem of poor catalyst coating adhesion durability, because metal supports will oxidize and decay in the natural environment, resulting in significant losses. Therefore, the catalyst will experience performance degradation after long-term use.

[0014] In existing technologies, the active components of catalysts are coated to achieve contact with volatile organic compounds by utilizing the structure of the support. The contact area is affected by the structure of the support, which mainly provides catalytic activity. Because the components within the catalyst are relatively simple and cannot form their own structure, it cannot have a significant positive impact on catalytic performance based on the support.

[0015] This invention employs a metal carrier, utilizing its heat and mass transfer properties to effectively enhance catalytic performance. The titanium oxide mixture contains three types of substances: titanium monoxide, titanium dioxide, and titanium trioxide. These three substances have different structures, resulting in a three-dimensional layered structure after mixing. This layered structure in the titanium oxide mixture allows for the formation of a larger contact area on the metal carrier, enabling the active components to adhere to this structure. This effectively increases the contact area between the active components and reactants, thereby improving catalyst efficiency. The three-dimensional structure increases the attachment space for the active components through spatial construction, and the layering creates numerous pores, further increasing the contact area between the active components and reactants.

[0016] In this invention, the combination of the titanium oxide mixture and the active component can inhibit the adsorption of sulfur dioxide and improve sulfur resistance; the noble metal element and the transition metal oxide are stably combined to inhibit their own displacement and agglomeration, thereby achieving a long service life of the catalyst. This can effectively avoid the natural environmental losses that occur when using a metal support, achieving the goal of both utilizing the advantages of the metal support and avoiding its service life defects.

[0017] In this invention, after pretreatment, a thin layer of alumina is formed on the inner surface of the metal carrier. After casting the alumina layer, the two form a laminated structure. After a certain period of high-temperature calcination, diffusion sintering between the alumina particles is achieved, forming a dense alumina laminated structure. This enhances the bonding strength with the carrier, promotes the adsorption and diffusion of reactants within the coating, improves heat and mass transfer efficiency, and achieves high-efficiency catalyst conversion. The addition of a binder changes the surface roughness of the alumina layer, enhancing the bonding stability with the titanium dioxide material. The pretreated alumina layer on the inner surface of the carrier and the added alumina layer are sintered to form a whole, connecting the metal carrier and the titanium dioxide mixture, and anchoring the three to form a strongly bonded coating, reducing the risk of cracking and peeling, and improving the overall erosion resistance of the catalyst.

[0018] Furthermore, the alumina layer comprises alumina and additives, wherein the alumina content is 15.000% to 30.000% by mass, and the additives account for 70.000% to 85.000%.

[0019] Furthermore, in the titanium oxide mixture, the titanium monoxide accounts for 0.000 wt% to 10.000 wt%, the titanium dioxide accounts for 80.000 wt% to 100.000 wt%, and the titanium trioxide accounts for 0.000 wt% to 10.000 wt%.

[0020] Furthermore, the precious metal is either platinum or ruthenium, accounting for 0.007 wt% to 1.800 wt% of the total loading of the metal carrier;

[0021] The transition metal is one or a combination of any two of nickel, molybdenum, cerium, cobalt, zirconium, and tungsten. When one transition metal is selected, molybdenum or tungsten is preferred, and its oxide content is 3.500 wt% to 13.500 wt% of the total metal carrier loading. When two transition metals are selected, the total proportion of the two transition metal oxides is 3.510 wt% to 17.100 wt% of the total metal carrier loading, wherein one transition metal oxide accounts for 1 to 2 times the proportion of the noble metal, and the other transition metal oxide serves as a supplement.

[0022] Furthermore, it also includes an adhesive, which includes one or any combination of silica sol, zirconium sol, aluminum sol, carboxymethyl cellulose, and polyvinylpyrrolidone, and the adhesive accounts for 5.000 wt% to 15.000 wt% of the total load of the metal carrier.

[0023] A method for preparing a sulfur-resistant and erosion-resistant metal honeycomb VOCs catalyst further includes the following steps:

[0024] Pre-treat and clean the metal carrier;

[0025] Preparation of alumina layer solution;

[0026] Preparation of titanium oxide mixtures;

[0027] Prepare an active component precursor solution; then add a titanium oxide mixture and a binder to it and mix evenly to form a catalyst slurry;

[0028] An alumina layer solution is cast onto a metal carrier, and after drying, the catalyst slurry is cast onto the metal carrier.

[0029] The coated metal support is continuously dried and calcined to obtain a metal honeycomb VOCs catalyst.

[0030] Currently, in existing technologies, catalysts are mainly prepared by directly coating the active components onto the support. This approach relies excessively on the structural characteristics of the support itself and fails to effectively utilize the inherent properties of the catalyst slurry.

[0031] In the catalyst preparation process of the present invention, the noble metal salt and the transition metal salt are first dissolved and mixed evenly to make the noble metal and the transition metal more uniformly mixed, so that the dispersion of the active component and the layered structure in the titanium oxide mixture are more uniformly mixed, thereby increasing the area on which the active component is attached. Then, the addition of reducing agent, auxiliary agent and binder to the intermediate mixture can improve the adhesion of the catalyst slurry, so that the active component can be more stably attached to the metal support for a long time.

[0032] Based on this, the metal carrier is coated with an alumina layer and a catalyst slurry by casting, which can improve the uniformity and stability of the coating. Moreover, during the layered casting process, a more three-dimensional layered structure can be constructed, thereby further increasing the adhesion area of ​​the active components and achieving a stable and efficient catalytic effect.

[0033] Furthermore, the pretreatment of the metal carrier includes the following steps:

[0034] The metal carrier is placed in a temperature environment of 350℃~500℃ and calcined for 1h~3h, then cooled to room temperature. The cleaning of the metal carrier includes the following steps: purging the metal carrier with compressed air of 0.2MPa.

[0035] Furthermore, the alumina layer includes the following steps:

[0036] Alumina powder and additives are mixed and heated to 60℃~90℃ and kept at that temperature for 1h-3h to prepare an alumina layer solution. The additives include one or any combination of carboxymethyl cellulose, polyvinyl alcohol, polyethylene glycol, silica sol, aluminum sol, acetic acid, and nitric acid.

[0037] Furthermore, the preparation of the titanium oxide mixture includes the following steps:

[0038] Titanium dioxide powder, titanium monoxide powder, and titanium trioxide powder are added to an alcohol solvent in a certain proportion, with the mass ratio of alcohol to powder being 1:1.0-1.5. The pH value of the mixture is adjusted to 3-6. The mixture is stirred at 50℃-80℃ for 1-3 hours, dried at 110℃-130℃ for 0.5-2 hours, calcined at 350℃-450℃ for 1-3 hours, ground, and sieved to obtain a titanium oxide mixture. The alcohol solvent includes one or any combination of ethanol, propanol, ethylene glycol, glycerol, isopropanol, and n-butanol.

[0039] When adding titanium dioxide powder, titanium monoxide powder, and titanium trioxide powder in proportion, the proportions are as follows: titanium monoxide 0.000wt% to 10.000wt%, titanium dioxide 80.000wt% to 100.000wt%, and titanium trioxide 0.000wt% to 10.000wt%.

[0040] Furthermore, the preparation of the catalyst slurry includes the following steps:

[0041] Add a transition metal salt solution to the noble metal salt solution, dissolve and mix thoroughly, stir for 0.5 h to 3 h, and adjust the pH value to 3 to 6.

[0042] A reducing agent and auxiliaries are added to carry out a reduction reaction. The temperature is raised to 60℃~90℃ and kept at the temperature for 1h~3h to obtain a precursor solution of the active component.

[0043] Add the titanium oxide mixture to the active component precursor solution, heat to 60℃~90℃, and keep warm for 1h~3h;

[0044] The reducing agent includes one or any combination of ethylene glycol, glucose, sodium borohydride, ascorbic acid, ethylenediamine, and ethanolamine, and its content is 3 to 5 times that of the precious metal.

[0045] The additives include one or any combination of hydrochloric acid, nitric acid, acetic acid, oxalic acid, and citric acid, and their content is 2 to 10 times that of the precious metal.

[0046] After the heat preservation is completed, the solution is cooled to room temperature, and then a binder is added to make a catalyst slurry.

[0047] The binder includes one or more of silica sol, zirconium sol, aluminum sol, carboxymethyl cellulose, and polyvinylpyrrolidone, and the binder accounts for 3.500 wt% to 13.500 wt% of the total loading of the metal carrier.

[0048] Furthermore, the casting of the metal carrier includes the following steps:

[0049] The alumina layer solution and catalyst slurry are sequentially poured into the surface of the metal carrier and the surface of its internal channels in fluid form, and the metal carrier is then allowed to stand.

[0050] Repeatedly apply the coating, drain, and dry the metal carrier, pre-set the coating quality of the metal carrier, and repeat the coating of the metal carrier until the alumina layer solution and catalyst slurry solution reach the pre-set coating quality of the metal carrier.

[0051] The drying of the metal carrier includes the following steps: placing the metal carrier in a temperature environment of 110℃~130℃ for 0.5h~1h and cooling it to room temperature;

[0052] The calcination of the metal carrier includes the following steps: placing the metal carrier in a temperature environment of 350℃~500℃ for 1h~3h and cooling it to room temperature.

[0053] In summary, the present invention has the following advantages compared with the prior art:

[0054] The present invention discloses a sulfur-resistant and erosion-resistant metal honeycomb VOCs catalyst in which a layered structure of titanium oxide mixture is used to construct a stable attachment space for active components, thereby improving the stability of the catalyst and effectively increasing the contact area of ​​active components, thus achieving the purpose of increasing catalytic efficiency.

[0055] The pretreated alumina layer on the inner surface of the carrier is sintered with the added alumina layer to form a whole, connecting the metal carrier and the titanium oxide mixture, and the three are riveted to form a coating with strong bonding force, which effectively improves long-term stability and avoids the problem of reduced catalyst efficiency due to structural damage to the coating. Combined with the stable use of the metal carrier and the increased adhesion area of ​​the active components, the present invention can obtain excellent catalytic efficiency and long-term catalytic stability.

[0056] In a method for preparing a sulfur-resistant and erosion-resistant metal honeycomb VOCs catalyst, the mixing uniformity of noble metal ions and transition metal ions is enhanced by first mixing noble metal salt solution and transition metal salt solution, thereby ensuring the stability of the catalyst during use. Secondly, by mixing titanium oxide mixture and metal mixed salt solution, the layered structure of titanium oxide mixture can more fully accommodate and contact the metal mixed salt solution, thereby achieving the purpose of improving catalytic efficiency by utilizing the layered structure of titanium oxide mixture.

[0057] In summary, this invention discloses a sulfur-resistant and erosion-resistant metal honeycomb VOCs catalyst and its preparation. It effectively enhances catalytic performance by utilizing the heat and mass transfer properties of the metal support. The titanium oxide mixture contains titanium monoxide, titanium dioxide, and titanium trioxide, which, after mixing, form a three-dimensional structure with a larger contact area, effectively increasing the contact area with reactants. The combination of the titanium oxide mixture and the active components inhibits the adsorption of sulfur dioxide, improving sulfur resistance. The stable combination of noble metal elements and transition metal oxides inhibits displacement and aggregation, preventing... During use, the active components are lost. The alumina layer on the inner surface of the metal carrier, together with the cast alumina layer, diffuses and sintersects to form a dense alumina laminate structure, which enhances the bonding strength with the carrier and improves the heat and mass transfer efficiency while achieving high catalyst conversion efficiency. The addition of a binder changes the surface roughness of the alumina layer and enhances the bonding stability with the titanium dioxide mixture. Based on the treated alumina layer on the inner surface of the carrier, the metal carrier and the titanium dioxide mixture are connected by the added alumina layer, and the three are anchored to form a strong bonding coating, reducing the risk of cracking and peeling and improving the catalyst's erosion resistance. Attached Figure Description

[0058] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and form part of this application, do not constitute a limitation thereof. In the drawings:

[0059] Figure 1 This is a SEM image of the titanium dioxide material after mixing according to the present invention;

[0060] Figure 2 SEM image of the catalyst coating;

[0061] Figure 3 This is a diagram showing the fresh performance of the catalyst of this invention;

[0062] Figure 4 This is a diagram showing the aging performance of the catalyst of this invention. Detailed Implementation

[0063] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0064] Example:

[0065] This embodiment relates to a sulfur-resistant and erosion-resistant metal honeycomb VOCs catalyst, comprising a metal support, wherein an alumina layer and a mixed layer are sequentially coated on the metal support. The mixed layer is composed of a titanium oxide mixture, an active component, and a binder. The metal support is a metal honeycomb support.

[0066] The alumina layer accounts for 10.000 wt% to 30.000 wt% of the total load of the metal carrier;

[0067] The titanium oxide mixture comprises titanium monoxide, titanium dioxide, and titanium trioxide, wherein the titanium monoxide, titanium dioxide, and titanium trioxide are mixed to form a layered structure; the titanium oxide mixture accounts for 44.800 wt% to 80.973 wt% of the total loading of the metal carrier;

[0068] The active component is a mixture of reduced noble metals and transition metal oxides. The proportion of noble metals is 0.007 wt% to 1.800 wt% of the total loading of the metal carrier, and the proportion of transition metal oxides is 3.510 wt% to 17.100 wt% of the total loading.

[0069] The binder accounts for 3.500 wt% to 13.500 wt% of the total load of the metal carrier;

[0070] The alumina layer comprises alumina and additives, wherein the alumina accounts for 15.000 wt% to 30.000 wt% of the alumina layer by mass, and the additives account for 70.000% to 85.000% of the alumina layer by mass.

[0071] In the titanium oxide mixture, the titanium monoxide accounts for 0.000 wt% to 10.000 wt%, the titanium dioxide accounts for 80.000 wt% to 100.000 wt%, and the titanium trioxide accounts for 0.000 wt% to 10.000 wt%.

[0072] The precious metal is either platinum or ruthenium, accounting for 0.007 wt% to 1.800 wt% of the total loading of the metal carrier;

[0073] The transition metal is one or any combination of two of nickel, molybdenum, cerium, cobalt, zirconium, and tungsten. When one transition metal is selected, molybdenum or tungsten is preferred, and the oxide accounts for 3.500 wt% to 13.500 wt% of the total loading of the metal carrier. When two transition metals are selected, the total proportion of the two transition metal oxides is 3.510 wt% to 17.100% of the total loading of the metal carrier, wherein the proportion of one transition metal oxide is 1 to 2 times that of the noble metal, and the other transition metal oxide is used as a surplus supplement.

[0074] It also includes a binder, which includes one or any combination of two or more substances such as silica sol, zirconium sol, aluminum sol, carboxymethyl cellulose, and polyvinylpyrrolidone, and the binder accounts for 3.500 wt% to 13.500 wt% of the total load of the metal carrier.

[0075] In a preferred embodiment, such as Figures 1-4 As shown, the metal carrier is made of iron-chromium-aluminum alloy, including an outer shell and foil strip, with a honeycomb mesh count of 100-900 mesh. Cylindrical dimensions: radius: 50mm-550mm, height: 50mm-200mm; Square dimensions: length: 100mm-1000mm, width: 100mm-1000mm, height: 50mm-300mm.

[0076] This ensures that the catalytic function can be achieved in this embodiment, and also improves the stability of the metal support and the contact area of ​​the active components of the metal support.

[0077] This embodiment also relates to a method for preparing a sulfur-resistant and erosion-resistant metal honeycomb VOCs catalyst, comprising the following steps:

[0078] Pre-treat and clean the metal carrier;

[0079] Preparation of alumina layer solution;

[0080] Prepare noble metal salt solutions and transition metal salt solutions, add and mix them in the designed mass ratio to dissolve the noble metal salts and transition metal salts, and prepare an active component precursor solution.

[0081] Add the active component precursor solution to the titanium oxide mixture and mix evenly to form an intermediate mixture. Then add a reducing agent, an auxiliary agent and a binder to the intermediate mixture to prepare a catalyst slurry.

[0082] An alumina layer solution is cast onto a metal carrier, and after drying, the catalyst slurry is cast onto the metal carrier.

[0083] The coated metal support is continuously dried and calcined to obtain a metal honeycomb VOCs catalyst.

[0084] In this embodiment, the heat and mass transfer properties of the metal support are utilized to effectively enhance catalytic performance. The titanium oxide mixture contains three types of substances: titanium monoxide, titanium dioxide, and titanium trioxide. These three substances have different structures, and after mixing, they form a three-dimensional structure with a larger contact area on the metal support. The active component adheres to this structure, effectively increasing the contact area with the reactants and improving catalyst efficiency. The combination of the titanium oxide mixture and the active component inhibits the adsorption of sulfur dioxide, improving sulfur resistance. The stable combination of noble metal elements and transition metal oxides inhibits displacement and agglomeration, avoiding loss of active components during use and achieving a long catalyst lifespan. After pretreatment, a thin layer of alumina forms on the inner surface of the catalyst. Combined with the cast alumina layer, the alumina particles are diffusely sintered after a certain period of high-temperature calcination, forming a dense alumina laminate structure. This enhances the bonding strength with the carrier, improves heat and mass transfer efficiency, and achieves high-efficiency catalyst conversion. The addition of a binder changes the surface roughness of the alumina layer, enhancing the bonding stability with the titanium dioxide mixture. Based on the alumina layer on the inner surface of the treated carrier, the added alumina layer connects the metal carrier and the titanium dioxide mixture, anchoring the three together to form a strong bonding coating, reducing the risk of cracking and peeling, and improving the catalyst's resistance to erosion.

[0085] The final results show that after being subjected to a high temperature of 650℃ and purged for a long time (10 min) under a gas pressure of 0.7MPa, the coating does not crack and the peeling rate is ≤1%; and it has good catalyst freshness and aging performance under a certain sulfur-containing atmosphere.

[0086] Furthermore, the preparation of the catalyst slurry includes the following steps:

[0087] The precious metal salt and transition metal salt are dissolved and mixed evenly, and stirred for 0.5 h to 1 h to adjust the pH value to 3 to 6.

[0088] A reducing agent and auxiliaries are added to carry out a reduction reaction. The temperature is raised to 60℃~90℃ and kept at the temperature for 1h~3h to obtain a precursor solution of the active component.

[0089] At this point, by heating the mixed solution of noble metal salt, transition metal salt, reducing agent and auxiliaries to 60°C and holding it at this temperature for 1 to 3 hours, an effective catalytic concentration of the active component can be obtained.

[0090] If the temperature is raised to 75℃ and kept at that temperature for 1 to 3 hours, the concentration of the active component can reach its peak.

[0091] If the temperature is raised to 90℃ and kept at that temperature for 1 to 3 hours, other chemical reactions occur, and the concentration of the active component tends to decrease.

[0092] The main influencing factor here is temperature. A heat preservation time of 1 to 3 hours can achieve the desired effect. If the time is less than 1 hour, the temperature transfer will not be uniform enough, and if the time exceeds 3 hours, there is a risk of additional chemical reactions.

[0093] Add the titanium dioxide mixture to the active component solution, heat to 60℃~90℃, and maintain the temperature for 1h~3h.

[0094] When the mixture of titanium oxide, active component solution, and binder is heated to 60°C and kept at that temperature for 1 to 3 hours, the titanium oxide mixture can be dispersed in the active component solution without producing additional reactions, thus ensuring the stability of the titanium oxide mixture's composition.

[0095] If the temperature is raised to 75°C and held for 1 to 3 hours, the titanium dioxide mixture can be dispersed in the active component solution without producing additional chemical reactions, ensuring the stability of the titanium dioxide mixture's composition.

[0096] If the temperature is raised to 90℃ and held for 1 to 3 hours, the titanium dioxide mixture can be dispersed in the active component solution without producing additional chemical reactions, ensuring the stability of the titanium dioxide mixture's composition.

[0097] The main influencing factor here is temperature. Within a certain temperature range, the diffusion rate of the titanium oxide mixture is accelerated, and the stability is guaranteed. Therefore, the effect can be achieved within the range of 1 hour to 3 hours. If the time is less than 1 hour, the temperature transfer will not be uniform enough, and if the time exceeds 3 hours, there is a risk of additional chemical reactions.

[0098] After the heat preservation is completed, the solution is cooled to room temperature, and then a binder is added to make a catalyst slurry.

[0099] The reducing agent includes one or a combination of any two or more substances such as ethylene glycol, glucose, sodium borohydride, ascorbic acid, ethylenediamine, and ethanolamine.

[0100] The additives include one or any combination of two or more substances selected from hydrochloric acid, nitric acid, acetic acid, oxalic acid, and citric acid.

[0101] Furthermore, the preparation of the titanium dioxide mixture includes the following steps: adding titanium dioxide powder, titanium monoxide powder, and titanium trioxide powder to an alcohol solvent in a certain proportion, wherein the mass ratio of alcohol to powder is 1:1.0 to 1.5; adjusting the pH value of the mixture to 3 to 6; stirring the mixture at 50℃ to 80℃ for 1 to 3 hours; drying the mixture at 110℃ to 130℃ for 0.5 to 2 hours; calcining the mixture at 350℃ to 450℃ for 1 to 3 hours; grinding; and sieving to obtain the titanium dioxide mixture.

[0102] The alcohol solvent includes one or any combination of two or more substances selected from ethanol, propanol, ethylene glycol, glycerol, isopropanol, and n-butanol;

[0103] The preparation of the alumina layer solution includes the following steps: mixing alumina powder and additives, heating to 60℃~90℃, and holding at that temperature for 1h-3h to prepare the alumina layer solution;

[0104] At this point, the mixed solution of alumina powder and additives is heated to 60°C and kept at this temperature for 1 to 3 hours. The alumina powder diffuses evenly in the additives without any additional chemical reaction, ensuring the stability of the composition of the alumina layer solution.

[0105] If the temperature is raised to 75℃ and held for 1 to 3 hours, the alumina powder will diffuse evenly in the additives without any additional chemical reaction, ensuring the stability of the composition of the alumina layer solution.

[0106] If the temperature is raised to 90℃ and held for 1 to 3 hours, the alumina powder will diffuse evenly in the additives without any additional chemical reaction, ensuring the stability of the composition of the alumina layer solution.

[0107] The main influencing factor here is temperature. Within a certain temperature range, the diffusion rate of alumina is accelerated, and the stability is guaranteed. Therefore, the effect can be achieved within the range of 1 hour to 3 hours. If the time is less than 1 hour, the temperature transfer is not uniform enough, resulting in uneven diffusion of alumina. If the time exceeds 3 hours, there is a risk of additional chemical reactions.

[0108] The additives include one or a combination of any two or more of the following substances: carboxymethyl cellulose, polyvinyl alcohol, polyethylene glycol, silica sol, aluminum sol, acetic acid, and nitric acid.

[0109] Furthermore, the pretreated metal carrier includes the following steps: placing the metal carrier in a temperature environment of 350℃~500℃ for 1h~3h and cooling it to room temperature.

[0110] The cleaning of the metal carrier includes the following steps: purging the metal carrier with 0.2MPa compressed air.

[0111] The casting of the metal carrier includes the following steps: sequentially casting the alumina layer solution and catalyst slurry into the surface of the metal carrier and the surface of its internal channels in fluid form, and allowing the metal carrier to stand; repeating the coating of the metal carrier until the alumina layer solution and catalyst slurry solution reach the preset coating quality of the metal carrier;

[0112] The drying of the metal carrier includes the following steps: placing the metal carrier in a temperature environment of 110℃~130℃ for 0.5h~1h and cooling it to room temperature;

[0113] The calcination of the metal carrier includes the following steps: placing the metal carrier in a temperature environment of 350℃~500℃ for 1h~3h and cooling it to room temperature.

[0114] In this embodiment, when coating the alumina layer solution and the catalyst slurry, the alumina layer solution needs to be coated first and then the catalyst slurry needs to be coated. This improves the stability of the metal support by relying on the direct contact between the alumina layer and the metal support, and provides a more three-dimensional mounting space for the catalyst slurry by utilizing the combination of the alumina layer and the metal support.

[0115] In this embodiment, the following specific implementation method can be adopted:

[0116] The components are proportioned according to a preferred scheme of a sulfur-resistant and erosion-resistant metal honeycomb VOCs catalyst of this embodiment, as a basic example 1:

[0117] Pretreatment carrier: Selected The metal honeycomb carrier has an outer foil strip made of iron-chromium-aluminum, and is pretreated by calcination at 500℃ for 1 hour and then cooled to room temperature.

[0118] Preparation of alumina layer solution: Alumina powder, polyvinyl alcohol solution, polyethylene glycol solution, nitric acid solution, and silica sol are mixed in a mass ratio of 30:6:1:118:9, heated to 80℃, and kept at that temperature for 1 hour to prepare an alumina layer solution.

[0119] Preparation of titanium oxide mixture: Titanium monoxide, titanium dioxide, and titanium trioxide powders were added to ethylene glycol in a mass ratio of 5:90:5, with a powder to ethylene glycol mass ratio of 1.2:1. The pH was adjusted to 6.0, and the mixture was stirred at 60°C for 1 hour. After drying at 120°C for 1 hour, calcining at 400°C for 1 hour, grinding, and sieving, the titanium oxide mixture was obtained.

[0120] Preparation of the active component precursor solution: Based on the total loading of the metal support, platinum salt was added at 1.154% of the total metal support loading, zirconium salt at 2.308% of the total metal support loading, and tungsten salt at 6.713% of the total metal support loading. The mixture was dissolved and stirred for 0.5 hours, and the pH was adjusted to 4.0. Ascorbic acid was added at a mass three times that of platinum, followed by oxalic acid at a mass ten times that of platinum. After stirring until homogeneous, the solution was heated to 80°C and kept at this temperature for 1 hour with stirring. This yielded the active component precursor solution.

[0121] Preparation of catalyst slurry: Add the prepared titanium dioxide mixture at a mass of 60.414% of the total loading of the metal support, keep stirring and heat for 1 hour; after the heat treatment, cool the mixture to room temperature, then add silica sol at a mass (converted to silicon dioxide) of 7.843% of the total loading of the metal support, keep stirring for 0.5 hours to prepare the catalyst slurry.

[0122] Catalyst preparation: An alumina layer solution was uniformly distributed along the honeycomb channels of the support using a casting method. After standing for 30 seconds, excess alumina layer solution was drained. The support was then dried at 110℃ for 0.5 hours and weighed to ensure a residual alumina layer mass of 0.542 g after drying. The catalyst slurry was again uniformly distributed along the honeycomb channels of the support using a casting method. After standing for 30 seconds, excess catalyst slurry was drained and dried at 110℃ for 0.5 hours. The cast catalyst was then calcined at 500℃ for 1 hour to ensure a residual dry basis mass of 1.973 g after removing the alumina layer. This is labeled as Basic Example 1.

[0123] Based on Basic Example 1, comparative examples are designed. In this embodiment, Basic Example 1 and Comparative Examples 1 to 17 are all specific implementations of the present invention that require protection.

[0124] Comparative Example 1: In this comparative example, the catalyst preparation process is the same as in Basic Example 1, except that the mass ratio of titanium monoxide, titanium dioxide, and titanium trioxide is 0:9:1. It is labeled as Comparative Example 1.

[0125] Comparative Example 2: In this comparative example, the catalyst preparation process is the same as in Basic Example 1, except that the mass ratio of titanium monoxide, titanium dioxide, and titanium trioxide is 1:9:0. It is labeled as Comparative Example 2.

[0126] Comparative Example 3: In this comparative example, the catalyst preparation process is the same as in Basic Example 1, except that the mass ratio of titanium monoxide, titanium dioxide, and titanium trioxide is 1:8:1. It is labeled as Comparative Example 3.

[0127] Comparative Example 4: In this comparative example, the catalyst preparation process is the same as in Basic Example 1, except that the mass ratio of titanium monoxide, titanium dioxide, and titanium trioxide is 0:10:0. It is labeled as Comparative Example 4.

[0128] Basic Example 1 and Comparative Examples 1-4 use the same transition metal and binder, but the proportions of titanium monoxide, titanium dioxide, and titanium trioxide in the titanium oxide mixtures are different. The purpose is to compare the differences in the freshness and aging performance of catalysts with different proportions of titanium oxide mixtures.

[0129] Comparative Example 5: In this comparative example, the catalyst preparation process is the same as in Basic Example 1, except that tungsten salt and zirconium salt are not added, only platinum salt is used, with the proportion remaining the same, only the type is changed. It is labeled as Comparative Example 5.

[0130] Comparative Example 6: In this comparative example, the catalyst preparation process is the same as in Basic Example 1, except that zirconium salt is not added, and only platinum salt and tungsten salt are used, with the proportions remaining the same. It is labeled as Comparative Example 6.

[0131] Comparative Example 7: In this comparative example, the catalyst preparation process is the same as in Basic Example 1, except that the zirconium salt is replaced with a nickel salt, with the proportion remaining the same, only the type is changed. It is labeled as Comparative Example 7.

[0132] Comparative Example 8: In this comparative example, the catalyst preparation process is the same as in Basic Example 1, except that tungsten salt and zirconium salt are replaced with nickel salt and cerium salt in the same proportion, only the types are changed. It is marked as Comparative Example 8.

[0133] In Basic Example 1 and Comparative Examples 5-8, the titanium oxide mixtures contained titanium monoxide, titanium dioxide, and titanium trioxide in the same proportion, but different types of transition metals in the same proportion. The purpose was to compare the differences in the freshness and aging performance of catalysts with different types of transition metals.

[0134] Comparative Example 9: In this comparative example, the catalyst preparation process is the same as in Basic Example 1, except that the silica sol is replaced with zirconium sol in the same molar ratio. It is labeled Comparative Example 9.

[0135] Comparative Example 10: In this comparative example, the catalyst preparation process was the same as in Basic Example 1, except that the silica sol was replaced with aluminum sol in the same molar ratio. It is labeled Comparative Example 10.

[0136] Comparative Example 11: In this comparative example, the catalyst preparation process is the same as in Basic Example 1, except that the silica sol is removed and no binder is added. It is labeled Comparative Example 11.

[0137] Comparative Example 12: In this comparative example, the catalyst preparation process was the same as in Basic Example 1, except that the silica sol was replaced with polyvinylpyrrolidone in the same molar ratio. It is labeled as Comparative Example 12.

[0138] Comparative Example 13: In this comparative example, the catalyst preparation process is the same as that of Basic Example 1, except that the silica sol is replaced with carboxymethyl cellulose in the same molar ratio and labeled as Comparative Example 13.

[0139] Comparative Example 14: In this comparative example, the catalyst preparation process is the same as that of Basic Example 1, except that the silica sol is replaced with a 1:1 mass mixture of silica and zirconium sol in the same molar ratio, and this is labeled as Comparative Example 14.

[0140] Comparative Example 15: In this comparative example, the catalyst preparation process is the same as that of Basic Example 1, except that the silica sol is replaced with a 1:1 mass mixture of zirconium and aluminum sol in the same molar ratio, and this is labeled as Comparative Example 15.

[0141] Comparative Example 16: In this comparative example, the catalyst preparation process is the same as that of Basic Example 1, except that the silica sol is replaced with a 1:1 mixture of aluminum sol and polyvinylpyrrolidone in the same molar ratio, and this is labeled as Comparative Example 16.

[0142] Comparative Example 17: In this comparative example, the catalyst preparation process is the same as that of Basic Example 1, except that the silica sol is replaced with a mixture of aluminum sol, polyvinylpyrrolidone, and carboxymethyl cellulose in a mass ratio of 1:1:1, and this is labeled as Comparative Example 17.

[0143] The difference between Basic Example 1 and Comparative Examples 9-17 lies in the different types of binders chosen, with the aim of investigating the effect of different binders on the catalyst shedding rate.

[0144] By comparing the freshness and aging performance test results of Basic Example 1 and Comparative Examples 1-4, such as Figure 3 , Figure 4 As shown, the results indicate that:

[0145] The basic example shows a 5%-15% improvement in freshness and a 10%-30% improvement in aging performance compared to the comparative example, thanks to the layered structure formed by the proportionally mixed titanium dioxide mixture, such as... Figure 1 As shown, more attachment sites are provided for the active components, increasing the amount of active components attached and increasing the contact area with the reactants, thus improving the freshness of the catalyst. With the increase of the proportion of titanium monoxide and titanium trioxide materials, the surface attachment sites are overlapped and covered, the amount of attachment decreases, and the catalyst performance is affected and reduced. The single titanium dioxide mixture cannot form a layered structure, the spatial structure is not effectively utilized, the attachment sites are reduced, the amount of attachment decreases, and the catalyst performance is affected and reduced. After long-term use, the layered structure effectively inhibits the collapse of the titanium oxide mixture, avoids the overlap and coverage between active components, and maintains the catalyst performance.

[0146] By comparing the freshness and aging performance test results of Basic Example 1 and Comparative Examples 5-8, such as... Figure 3 , Figure 4 As shown, the results indicate that:

[0147] The platinum-tungsten-zirconium composite oxide formed after calcination effectively inhibits platinum displacement and agglomeration, maintaining high dispersibility, stable particle size, and electronic state of platinum. The appropriate ratio of platinum, tungsten, and zirconium fully utilizes the performance of the oxide, enhances the interaction between active components, improves its own stability, and achieves a long service life for the catalyst. The composite oxide and titanium oxide mixture work together to ensure the acidity of the catalyst, inhibit the adsorption of sulfur dioxide by the catalyst, and improve sulfur resistance, so that the catalyst can still maintain good fresh aging performance in a sulfur-containing atmosphere.

[0148] The coating peeling rate was tested on Basic Example 1 and Comparative Examples 9-17. In this example, the coating is the total load of the metal carrier.

[0149] The coating peeling rate test method is as follows:

[0150] Before testing, the catalyst needs to be kept at 120℃ for 1 hour and weighed, recorded as M1 in g. After cooling to room temperature for 1 hour and removing oil and water, compressed air (0.7±0.05) MPa, with a pipe diameter of 0.008m, is used to purge the catalyst end face from a distance of ≤3cm. The end face is purged evenly and slowly for at least 3 cycles, and it is observed that there is no dust falling off or flying off the catalyst. The catalyst is then kept at 120℃ for 1 hour again and weighed, recorded as M2 in g. The calculated value of the catalyst coating mass (catalyst volume × loading) is recorded as M0 in grams (g).

[0151] After the catalyst coating peeling test, the percentage of the weight of the catalyst coating that peeled off to the total weight of the catalyst coating was calculated as follows:

[0152]

[0153] In the formula:

[0154] μ — Coating peeling rate, %;

[0155] M1 — Sample mass before testing, in grams (g);

[0156] M2 — Mass of the sample after testing, in grams (g);

[0157] M0 — Coating mass in the catalyst, in grams (g).

[0158] The results of the shedding rate tests for Basic Example 1 and Comparative Examples 9–17 are shown in Table 1, combined with the attached... Figure 2The results showed that the addition of silica sol as a binder altered the surface roughness of the alumina layer, enhancing its bonding stability with the titanium dioxide mixture. Based on the treated alumina layer on the inner surface of the carrier, the added alumina layer connected the metal carrier and the titanium dioxide mixture, forming a strongly bonded coating that reduced the risk of cracking and detachment, and improved the catalyst's resistance to erosion. This composition resulted in a coating detachment rate of ≤1% after the catalyst was subjected to 650℃ high temperature and 0.7MPa air pressure purging for 10 min.

[0159] Table 1: Catalyst shedding rate test

[0160] Theoretical coating mass (g) Before purging g After purging g shedding rate % Basic Example 1 1.54 1.54 1.53 0.65％ Comparative Example 9 1.54 1.54 1.32 14.52％ Comparative Example 10 1.54 1.54 1.38 10.63％ Comparative Example 11 1.54 1.54 0.63 59.04％ Comparative Example 12 1.54 1.54 1.12 27.41％ Comparative Example 13 1.54 1.54 1.42 7.91％ Comparative Example 14 1.54 1.55 1.49 3.89％ Comparative Example 15 1.54 1.54 1.41 8.36％ Comparative Example 16 1.54 1.54 1.32 14.45％ Comparative Example 17 1.54 1.54 1.05 31.89％

[0161] The catalyst performance testing methods are as follows:

[0162] The concentration of sulfur-containing waste gas before and after passing through the catalyst was detected using a chromatograph to determine the ignition temperature and conversion efficiency temperature. The catalyst was then aged in an atmosphere and tested under the same sulfur-containing atmosphere to determine the ignition temperature and conversion efficiency after aging. The test boundaries are as follows:

[0163] Table 2: Catalyst Aging Test Boundaries

[0164] Test atmosphere <![CDATA[50 ppm sulfur dioxide + 100 ppm propane, O2: 5%, H2O: 20%, balance gas: N2.]]> Aging conditions <![CDATA[650℃@20h, 10% H2O, 50 ppm sulfur dioxide, 1 Wh -1 > Test airspeed <![CDATA[2.5W h -1 ]]> Test temperature 120℃、250℃、300℃、350℃、400℃、450℃ Test status steady state

[0165] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A sulfur-resistant and erosion-resistant metal honeycomb VOCs catalyst, characterized in that, The system includes a metal carrier, on which an alumina layer and a hybrid layer are sequentially coated. The hybrid layer is composed of a titanium dioxide mixture, an active component, and a binder. The metal carrier is a metal honeycomb carrier; The alumina layer accounts for 10.000wt% to 30.000wt% of the total metal carrier load. The titanium oxide mixture comprises titanium monoxide, titanium dioxide, and titanium trioxide, wherein the titanium monoxide, titanium dioxide, and titanium trioxide are mixed to form a layered structure; the titanium oxide mixture accounts for 44.800 wt% to 80.973 wt% of the total metal carrier loading. The active component is a mixture of reduced noble metals and transition metal oxides, wherein the proportion of noble metals is 0.007 wt% to 1.800 wt% of the total loading of the metal carrier, and the proportion of transition metal oxides is 3.510 wt% to 17.100 wt% of the total loading. The binder accounts for 3.500wt% to 13.500wt% of the total load of the metal carrier.

2. The sulfur-resistant and erosion-resistant metal honeycomb VOCs catalyst according to claim 1, characterized in that, The alumina layer is made of alumina and additives, with alumina accounting for 15.000wt% to 30.000wt% of the alumina layer by mass and additives accounting for 70.000% to 85.000% of the alumina layer by mass.

3. The sulfur-resistant and erosion-resistant metal honeycomb VOCs catalyst according to claim 1, characterized in that, In the titanium oxide mixture, the titanium monoxide accounts for 0.000wt%~10.000wt%, the titanium dioxide accounts for 80.000wt%~100.000wt%, and the titanium trioxide accounts for 0.000wt%~10.000wt%.

4. The sulfur-resistant and erosion-resistant metal honeycomb VOCs catalyst according to claim 1, characterized in that, The precious metal is either platinum or ruthenium, accounting for 0.007 wt% to 1.800 wt% of the total loading of the metal carrier; The transition metal is one or any combination of two of the following: nickel, molybdenum, cerium, cobalt, zirconium, and tungsten.

5. The sulfur-resistant and erosion-resistant metal honeycomb VOCs catalyst according to claim 1, characterized in that, The binder includes one or any combination of two or more substances such as silica sol, zirconium sol, aluminum sol, carboxymethyl cellulose, and polyvinylpyrrolidone.

6. A method for preparing a sulfur-resistant and erosion-resistant metal honeycomb VOCs catalyst according to any one of claims 1 to 5, characterized in that, Includes the following steps: Pre-treat and clean the metal carrier; Preparation of alumina layer solution; Preparation of titanium oxide mixtures; Prepare an active component precursor solution; then add a titanium oxide mixture and a binder to it and mix evenly to form a catalyst slurry; An alumina layer solution is cast onto a metal carrier, and after drying, the catalyst slurry is cast onto the metal carrier. The coated metal support is continuously dried and calcined to obtain a metal honeycomb VOCs catalyst.

7. The preparation method of a sulfur-resistant and erosion-resistant metal honeycomb VOCs catalyst according to claim 6, characterized in that, The pretreated metal carrier includes the following steps: placing the metal carrier in a temperature environment of 350℃~500℃ for 1h~3h and cooling it to room temperature; The cleaning of the metal carrier includes the following steps: blowing the metal carrier with 0.2MPa compressed air.

8. The method for preparing a sulfur-resistant and erosion-resistant metal honeycomb VOCs catalyst according to claim 6, characterized in that, The preparation of the alumina layer solution includes the following steps: Alumina powder and additives are mixed and heated to 60℃~90℃, and kept at that temperature for 1h-3h to prepare an alumina layer solution. The additives include one or a combination of any two or more of the following substances: carboxymethyl cellulose, polyvinyl alcohol, polyethylene glycol, silica sol, aluminum sol, acetic acid, and nitric acid.

9. The method for preparing a sulfur-resistant and erosion-resistant metal honeycomb VOCs catalyst according to claim 6, characterized in that, The preparation of the titanium oxide mixture includes the following steps: Titanium dioxide powder, titanium monoxide powder, and titanium trioxide powder are added to an alcohol solvent at a ratio of 0-1 parts by weight of titanium dioxide powder, 8-10 parts by weight of titanium monoxide powder, and 0-1 parts by weight of titanium trioxide powder, with the alcohol to powder mass ratio being 1:1.0-1.

5. The pH value of the mixture is adjusted to 3-6. The mixture is stirred at 50℃-80℃ for 1-3 hours. The mixture is then dried at 110℃-130℃ for 0.5-2 hours, calcined at 350℃-450℃ for 1-3 hours, ground, and sieved to obtain a titanium oxide mixture. The alcohol solvent includes one or any combination of two or more substances selected from ethanol, propanol, ethylene glycol, glycerol, isopropanol, and n-butanol.

10. The method for preparing a sulfur-resistant and erosion-resistant metal honeycomb VOCs catalyst according to claim 6, characterized in that, The preparation of the catalyst slurry includes the following steps: Dissolve and mix the precious metal salt and transition metal salt evenly, stir for 0.5h~1h, and adjust the pH value to 3~6; Add reducing agent and auxiliary agent to carry out reduction reaction, heat to 60℃~90℃, keep warm for 1h~3h, and obtain active component precursor solution; Add the titanium oxide mixture to the active component precursor solution, heat to 60℃~90℃, and keep warm for 1h~3h; The reducing agent includes one or a combination of any two or more substances such as ethylene glycol, glucose, sodium borohydride, ascorbic acid, ethylenediamine, and ethanolamine, and its content is 3 to 5 times that of the precious metal. The additives include one or any combination of hydrochloric acid, nitric acid, acetic acid, oxalic acid, and citric acid, and their content is 2 to 10 times that of the precious metal. After the heat preservation is completed, the mixture is cooled to room temperature, then a binder is added and stirred for 0.5 to 1 hour to prepare a catalyst slurry. The binder includes one or any combination of two or more substances such as silica sol, zirconium sol, aluminum sol, carboxymethyl cellulose, and polyvinylpyrrolidone.

11. The method for preparing a sulfur-resistant and erosion-resistant metal honeycomb VOCs catalyst according to claim 6, characterized in that, The casting of the metal carrier includes the following steps: The alumina layer solution and catalyst slurry are sequentially poured into the surface of the metal carrier and the surface of its internal channels in fluid form, and the metal carrier is then allowed to stand. Repeat the coating process on the metal carrier until the alumina layer solution and catalyst slurry solution reach the preset coating quality of the metal carrier. The continuous drying of the metal carrier is called drying, which includes the following steps: placing the metal carrier in a temperature environment of 110℃~130℃ for 0.5h~1h and cooling it to room temperature; The calcination of the metal carrier includes the following steps: placing the metal carrier in a temperature environment of 350℃~500℃ for 1h~3h and cooling it to room temperature.

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