CN105728063B - A kind of preparation method of metal substrate catalyst - Google Patents

Abstract

The invention relates to the technical field of catalysis, in particular to a method for preparing a metal substrate catalyst. The catalyst coating prepared by the plasma spraying technology has strong adhesion and can improve the activity and stability of the catalyst. An embodiment of the present invention provides a method for preparing a metal-based catalyst, comprising: spraying a catalyst precursor as a spray powder on the surface of a metal substrate through a plasma spraying equipment to form a catalyst coating, wherein the catalyst precursor is composed of microsphere particles , the microsphere particles have a porous structure. The embodiments of the present invention are applied to the production and manufacture of metal substrate catalysts.

Description

A kind of preparation method of metal substrate catalyst

technical field

The invention relates to the technical field of catalysis, in particular to a method for preparing a metal substrate catalyst.

Background technique

Catalysts are widely used in chemical production, scientific experiments and daily life, especially in the catalytic combustion of new fuels. For example, the catalytic combustion of fuels such as methanol, methane and ethanol has become the focus of research.

Catalyst, also known as catalyst, can change the chemical reaction rate of other substances in a chemical reaction, and its own quality and properties do not change before and after the reaction. Therefore, the reuse of catalysts is particularly important. Metal-based catalysts have good mechanical strength and high temperature resistance, and have become a research hotspot. In the prior art, metal-based catalysts are usually prepared by impregnation. However, the obtained catalyst coating on the surface of the metal substrate has poor adhesion. It is easy to fall off and has poor stability, so that the catalytic activity of the metal substrate catalyst is reduced, and it is difficult to realize reuse.

Contents of the invention

The main purpose of the present invention is to provide a method for preparing metal-based catalysts. The catalyst coating prepared by plasma spraying technology has strong adhesion and can improve the activity and stability of the catalyst.

To achieve the above object, the present invention adopts the following technical solutions:

On the one hand, an embodiment of the present invention provides a method for preparing a metal substrate catalyst, comprising:

The catalyst precursor is sprayed on the surface of the metal substrate as a spray powder by plasma spray equipment to form a catalyst coating, wherein the catalyst precursor is composed of microsphere particles, and the microsphere particles have a porous structure.

Preferably, the catalyst precursor is prepared through the following steps:

Mix and grind the compound containing the catalytically active component, the pore former and the solvent to make a slurry;

The slurry is subjected to spray granulation, and calcined at a preset temperature for a preset time.

Optionally, the pore-forming agent is starch or/and polyethylene glycol.

Preferably, the preset temperature is 400-800° C., and the preset time is 2-3 hours.

Optionally, the diameter of the microsphere particles is 10-100 microns, the pore diameter of the porous structure is 5-100 nm, and the pore volume is 0.1-0.8 cm ³ /g.

Preferably, the metal substrate is a metal honeycomb substrate.

Optionally, the mesh of the honeycomb cells of the metal honeycomb base is 100-600, and the thickness of the cell walls is less than 1 mm.

Preferably, the metal honeycomb substrate includes a honeycomb structure, and the honeycomb structure includes bare surfaces extending along the radial direction of the honeycomb holes. During the spraying process, the spray gun outlet of the plasma spraying equipment Rotating spraying towards the exposed surface of the honeycomb structure, the angle between the spraying direction of the plasma spraying equipment and the plane where the exposed surface of the honeycomb structure is continuously changed within a preset range.

Further preferably, the range of the preset included angle is 30-150 degrees.

Optionally, the rate of continuous change is 10-50 degrees/min.

Preferably, the method further includes: adding auxiliary spraying powder to the catalyst precursor, and the auxiliary spraying powder is composed of solid microsphere particles.

Optionally, the spraying temperature of the plasma spraying equipment is lower than the melting point of the catalyst precursor.

Preferably, the gas flow rate of the plasma spraying equipment is 50-200 L/min.

Optionally, the powder feeding rate of the plasma spraying equipment is 5-100 g/min.

On the other hand, an embodiment of the present invention provides a metal substrate catalyst obtained by the above-mentioned preparation method, the metal substrate catalyst comprising: a metal substrate and a catalyst coating attached to the surface of the metal substrate.

Preferably, the catalyst coating has a porosity of 0.05-0.3.

An embodiment of the present invention provides a method for preparing a metal substrate catalyst. The catalyst precursor is sprayed on the surface of the metal substrate as a spray powder by plasma spraying technology. The catalyst precursor is composed of microsphere particles, and the microsphere The particles have a porous structure and can form a catalyst coating firmly attached to the surface of the metal substrate. Compared with the dipping method, the preparation process can improve the adhesion of the catalyst coating and reduce shedding, thereby improving the activity and stability of the catalyst. The invention overcomes the defect of poor catalyst coating adhesion in the prior art, resulting in poor activity and stability of the catalyst.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some of the embodiments of the present invention, but not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

On the one hand, an embodiment of the present invention provides a method for preparing a metal substrate catalyst, comprising:

The catalyst precursor is sprayed on the surface of the metal substrate as a spray powder by plasma spray equipment to form a catalyst coating, wherein the catalyst precursor is composed of microsphere particles, and the microsphere particles have a porous structure.

Plasma spraying is a material surface strengthening and surface modification technology, which can make the surface of the substrate have properties such as wear resistance, corrosion resistance, high temperature oxidation resistance, electrical insulation, heat insulation, radiation protection, wear reduction and sealing. Plasma spraying technology uses the plasma arc driven by direct current as the heat source to heat ceramics, alloys, metals and other materials to a molten or semi-molten state, and sprays them on the surface of the pretreated workpiece at high speed to form a firmly adhered surface layer. .

An embodiment of the present invention provides a method for preparing a metal substrate catalyst. The catalyst precursor is sprayed on the surface of the metal substrate by plasma spraying technology as a spray powder. The catalyst precursor is composed of microsphere particles, which can form a firm adhesion The catalyst coating on the surface of the metal substrate, and at the same time, because the microsphere particles have a porous structure, the specific surface area of the catalyst precursor can be increased, the adsorption active center of the catalyst can be increased, and the catalytic activity of the catalyst can be improved; Compared with the dipping method, the preparation process can improve the adhesion of the catalyst coating and reduce shedding, thereby improving the activity and stability of the catalyst. The invention overcomes the defect of poor catalyst coating adhesion in the prior art, resulting in poor activity and stability of the catalyst.

Wherein, the specific composition of the catalyst precursor is not limited. The catalyst precursor can be any spray powder containing catalytically active components.

Wherein, the acquisition of the catalyst precursor is not limited.

While the microsphere particles can be obtained through commercial channels, they can also be obtained by self-made.

In an embodiment of the present invention, the catalyst precursor is prepared through the following steps:

Mix and grind the compound containing the catalytically active component, the pore former and the solvent to make a slurry;

The slurry is subjected to spray granulation, and calcined at a preset temperature for a preset time.

In the embodiment of the present invention, the pore-forming agent can bind the compound containing the catalytically active component, and microsphere particles can be obtained by spray drying, and the obtained microsphere particles are calcined at a preset temperature for a preset time, The bonding sites form a pore structure, so that porous microsphere particles can be obtained.

Wherein, the compound containing catalytically active components may only include noble metal compounds, or may include both noble metal compounds and transition metal compounds.

Wherein, the pore former is not limited.

In one embodiment of the present invention, the pore-forming agent is starch or/and polyethylene glycol.

Wherein, the preset temperature and the preset time are not limited.

In an embodiment of the present invention, the preset temperature is 400-800° C., and the preset time is 2-3 hours.

Wherein, the specific structure of the microsphere particles is not limited.

In yet another embodiment of the present invention, the diameter of the microsphere particles is 10-100 microns, the pore diameter of the porous structure is 5-100 nm, and the pore volume is 0.1-0.8 cm ³ /g.

It should be noted that, in practical applications, the metal substrate usually has a porous structure, which is beneficial to increase the specific surface area of the catalyst and increase the catalytic active centers, thereby improving the catalytic activity of the catalyst.

Wherein, the specific structure of the metal base is not limited.

In an embodiment of the present invention, the metal substrate is a metal honeycomb substrate.

Wherein, the metal honeycomb substrate means that the metal substrate is in a honeycomb shape, and the use of the metal honeycomb substrate can increase the specific surface area of the metal substrate, thereby increasing the specific surface area of the catalyst coating and improving the catalytic activity of the metal substrate catalyst.

Wherein, the specific parameters of the honeycomb holes of the metal honeycomb base are not limited.

In yet another embodiment of the present invention, the mesh of the honeycomb cells of the metal honeycomb substrate is 100-600, and the thickness of the cell walls is less than 1 mm.

Wherein, the depth of the honeycomb holes of the metal honeycomb substrate is not limited.

In an embodiment of the present invention, the depth of the honeycomb holes of the metal honeycomb substrate is 2-20 mm.

Wherein, the specific operation of the plasma spraying is not limited.

In an embodiment of the present invention, the metal honeycomb substrate includes a honeycomb structure, and the honeycomb structure includes an exposed surface extending along the radial direction of the honeycomb holes. During the spraying process, the plasma The outlet of the spray gun of the spraying equipment rotates and sprays towards the exposed surface of the honeycomb structure, and the angle between the spraying direction of the plasma spraying equipment and the plane where the exposed surface of the honeycomb structure is located is within a preset range continuous change.

Wherein, the radial direction of the honeycomb hole refers to the direction forming an angle with the length direction of the honeycomb hole, and does not refer to the radial direction of the circular hole in the strict sense. In the embodiment of the present invention, through the operation of spraying while moving, the spray powder can be evenly sprayed on the surface of the metal honeycomb base, and by continuously changing the spray angle, the honeycomb cell walls of the metal honeycomb base can also be sprayed. The catalyst coating is evenly sprayed, so that the uniformity of the catalyst coating can be improved.

Wherein, the preset range is not limited. The preset range can be adjusted according to the specific distribution of the honeycomb cells of the metal honeycomb base, as long as the spray powder is evenly sprayed onto the walls of the honeycomb cells of the metal honeycomb base.

In an embodiment of the present invention, the preset range is 30-150 degrees.

In practical applications, the smaller the included angle, the weaker the binding force, which will easily cause poor adhesion of the catalyst coating and easy to fall off. Within this preset range, the spray powder can be sprayed evenly while ensuring the adhesion of the catalyst coating onto the loading surface of the metal substrate.

The rate of continuous change is also not limited.

In an embodiment of the present invention, the rate of continuous change is 10-50 degrees/min.

In the embodiment of the present invention, at an appropriate rate of change, the uniformity and efficiency of spraying can be ensured, and the spraying effect can be improved.

Wherein, the spraying parameters of the plasma spraying equipment are not limited.

In an embodiment of the present invention, the spraying power of the plasma spraying equipment is 40-80KW, the spraying current is 300-480A, and the spraying voltage is 140-170V.

In yet another embodiment of the present invention, the distance between the spray gun outlet of the plasma spraying equipment and the surface of the metal substrate is 50-150 mm.

The distance from the spray gun outlet to the load surface of the metal substrate affects the speed and temperature of the spray particles and the substrate when they impact. The characteristics of the coating and the spray material are sensitive to the spray distance. If the spraying distance is too large, the temperature and speed of the powder particles will decrease, and the bonding force, pores, and spraying efficiency will all decrease significantly; if the spraying distance is too small, the temperature of the substrate will rise too high, the substrate and coating will be oxidized, and the bonding of the coating will be affected. .

Wherein, it should be noted that in the plasma spraying process, the spraying temperature, powder feeding rate and gas flow all have a great influence on the specific surface area and spraying efficiency of the catalyst coating. The ideal catalyst coating can be obtained by adjusting various parameters.

In an embodiment of the present invention, the spraying temperature of the plasma spraying equipment is lower than the melting point of the catalyst precursor.

In the embodiment of the present invention, the spray powder can be in a semi-molten state, can be well combined with the metal substrate when the spray powder reaches the metal substrate, and can keep the porous structure of the porous microsphere particles from collapsing, thereby improving The specific surface area of the catalyst coating.

In yet another embodiment of the present invention, the gas flow rate of the plasma spraying equipment is 50-200 L/min.

The high air flow can make the spray powder not pile up tightly when it reaches the metal substrate, but form a certain pore structure, so that a catalyst coating with a pore structure can be obtained, and the specific surface area of the catalyst coating can be further increased.

In an embodiment of the present invention, the powder feeding rate of the plasma spraying equipment is 5-100 g/min.

The high powder feeding rate can also make the spray powder not pile up tightly when it reaches the metal substrate, but form a certain pore structure, so that a catalyst coating with a pore structure can be obtained, and the specific surface area of the catalyst coating can be further increased.

In an embodiment of the present invention, the method further includes: adding auxiliary spraying powder to the catalyst precursor, and the auxiliary spraying powder is composed of solid microsphere particles.

Because the microsphere particles have a porous structure, compared with the solid microsphere particles, the fluidity decreases during the powder feeding process. In the embodiment of the present invention, by adding the solid microsphere particles, the overall fluidity of the spray powder can be improved, and the catalytic performance of the catalyst can be improved. Coating adhesion and spraying effect.

Wherein, the particle size of the solid microsphere particles is equivalent to that of the porous microsphere particles.

In yet another embodiment of the present invention, the additive amount of the auxiliary spray powder is less than or equal to 20% of the total spray powder.

In yet another embodiment of the present invention, before spraying the catalyst precursor onto the loaded surface of the metal substrate, the method further includes: performing sand blasting treatment on the metal substrate.

The sand blasting treatment can increase the roughness of the supporting surface of the metal substrate, thereby improving the bonding firmness between the catalyst coating and the supporting surface.

Wherein, the sandblasting used in the sandblasting is not limited.

In an embodiment of the present invention, the sandblasting is 200-600 mesh quartz sand.

Sandblasting with the quartz sand of this mesh size can be moderately polished while ensuring that the pore walls and pore diameters of the metal honeycomb substrate are not affected, thereby improving the bonding firmness between the catalyst coating and the loaded surface.

On the other hand, an embodiment of the present invention provides a metal substrate catalyst obtained by the above-mentioned preparation method, the metal substrate catalyst comprising: a metal substrate and a catalyst coating attached to the surface of the metal substrate.

An embodiment of the present invention provides a metal-based catalyst, the metal-based catalyst is composed of a metal substrate and a catalyst coating attached to the surface of the metal substrate, and the catalyst coating is sprayed with a spray powder composed of microsphere particles through a plasma spraying process On the surface of the metal substrate, a certain pore structure can be formed. Compared with the metal substrate catalyst obtained by the impregnation method, the adhesion of the catalyst coating is strong, and the specific surface area of the catalyst coating is higher, which can increase the adsorption activity. In the center, the activity of the metal-based catalyst can be improved, so that the activity and stability of the metal-based catalyst can be improved as a whole. The invention overcomes the defect that the poor adhesion of the catalyst coating in the prior art results in poor activity and stability of the metal substrate catalyst.

Since the catalyst coating has a certain pore structure, the specific surface area of the catalyst coating can be increased, thereby improving the catalytic activity of the metal substrate catalyst.

Wherein, the porosity of the catalyst coating is not limited. The porosity of the catalyst coating can be obtained by changing process parameters.

In an embodiment of the present invention, the catalyst coating has a porosity of 0.05-0.3.

Under this porosity, the catalyst coating has good adsorption activity and a relatively suitable specific surface area, which can improve the catalytic activity of the metal substrate catalyst, improve the bonding force between the catalyst coating and the metal substrate, and reduce the catalyst coating. layer shedding.

Hereinafter, the embodiments of the present invention illustrate the present invention through comparative examples, examples and experimental examples. These examples are just examples to specifically illustrate the present invention, and those skilled in the art will understand that the scope of the present invention is not limited by these examples and experimental examples.

Comparative example

In the comparative example, the impregnation method was used to prepare the metal substrate catalyst, and the catalyst provided in the comparative example was Catalyst 5.

The specific preparation method of the catalyst 5 is: use the metal honeycomb substrate to contact the aqueous solution of metal salts, make the metal salt solution adsorb or store in the porous structure of the metal substrate, remove the excess solution, and then dry, calcinate and activate Catalyst 5 was prepared.

Example 1

The catalyst provided in Example 1 is Catalyst 1.

The concrete preparation method of described catalyst 1 is:

1. Prepare a catalyst precursor, the catalyst precursor is composed of porous microsphere particles, and the porous microsphere particles are prepared by the following method:

Mix and ball mill nano-alumina, chloroplatinic acid, starch and water to a uniform slurry;

The slurry is sprayed and granulated by a spray dryer, and calcined at 400°C for 2 hours to obtain porous microsphere particles of 10-100 microns, the pore diameter of the porous structure is 5-100 nm, and the pore volume is 0.1-0.8 cm ³ /g . Among them, the content of platinum is 0.5%.

2. Spray the obtained catalyst precursor as a spray powder on the surface of the metal honeycomb substrate through plasma spraying equipment, and the metal honeycomb substrate includes a honeycomb structure, and the honeycomb structure includes a diameter along the honeycomb hole. The exposed surface extending in the direction, in this process, the gas flow rate of the plasma spraying equipment is 50L/min, the distance between the spray gun outlet of the plasma spraying equipment and the surface of the metal substrate is 50mm, and the powder feeding amount is 5g/min, the spray gun outlet of the plasma spraying equipment rotates and sprays towards the exposed surface of the honeycomb structure, and the angle between the initial spraying direction and the plane where the exposed surface of the honeycomb structure is located is 30 degrees , the included angle changes continuously between 30-150 degrees at a rate of 10 degrees/min, wherein the mesh number of the honeycomb holes of the metal honeycomb base is 100 mesh, the depth of the honeycomb holes is 2 mm, and the thickness of the cell walls is less than 1 mm, The cross-sectional shape of the honeycomb cells was triangular, and the obtained catalyst coating had a porosity of 0.3.

Example 2

The catalyst provided in Example 2 is referred to as Catalyst 2.

The concrete preparation method of described catalyst 2 is:

1. Prepare a catalyst precursor, the catalyst precursor is composed of porous microsphere particles, and the porous microsphere particles are prepared by the following method:

Mix and ball mill nano-alumina, chloroplatinic acid, starch and water to a uniform slurry;

The slurry is sprayed and granulated by a spray dryer, and calcined at 600°C for 2.5 hours to obtain porous microsphere particles of 10-100 microns, the pore diameter of the porous structure is 5-100 nm, and the pore volume is 0.1-0.8 cm ³ / g. Among them, the content of platinum is 0.5%.

2. Add 20% solid spherical micro-particles to the obtained catalyst precursor to obtain spray powder. The solid spherical micro-particles are consistent with the composition of the porous micro-sphere particles and have a diameter of 10-100 microns, and the spray powder Spraying onto the surface of the metal honeycomb base by plasma spraying equipment, the metal honeycomb base includes a honeycomb structure, and the honeycomb structure includes an exposed surface extending along the radial direction of the honeycomb holes, during this process, The gas flow rate of the plasma spraying equipment is 100L/min, the distance between the spray gun outlet of the plasma spraying equipment and the surface of the metal substrate is 100mm, and the powder feeding rate is 50g/min, the spray gun of the plasma spraying equipment The exit is rotated and sprayed towards the exposed surface of the honeycomb structure, the angle between the initial spraying direction and the plane where the exposed surface of the honeycomb structure is located is 50 degrees, and the included angle is 30 degrees at a rate of 20 degrees/min. Continuous change between -150 degrees, wherein, the mesh number of the honeycomb holes of the metal honeycomb base is 200 mesh, the depth of the honeycomb holes is 10mm, the thickness of the hole walls is less than 1mm, the cross-sectional shape of the honeycomb holes is triangular, and the obtained catalyst The porosity of the coating was 0.05.

Example 3

The catalyst provided in Example 3 is referred to as Catalyst 3.

The concrete preparation method of described catalyst 3 is:

1. Prepare a catalyst precursor, the catalyst precursor is composed of porous microsphere particles, and the porous microsphere particles are prepared by the following method:

Mix and ball mill nano cerium oxide, palladium chloride, starch and water to a uniform slurry;

The slurry is sprayed and granulated by a spray dryer, and calcined at 800°C for 3 hours to obtain porous microsphere particles of 10-100 microns, the pore diameter of the porous structure is 5-100 nm, and the pore volume is 0.1-0.8 cm ³ /g . Wherein, the content of palladium is 0.5%.

2. Spray the obtained catalyst precursor as a spray powder on the surface of the metal honeycomb substrate through plasma spraying equipment, and the metal honeycomb substrate includes a honeycomb structure, and the honeycomb structure includes a diameter along the honeycomb hole. The bare surface extending in the direction, in this process, the gas flow rate of the plasma spraying equipment is 200L/min, the distance between the spray gun outlet of the plasma spraying equipment and the surface of the metal substrate is 150mm, and the powder feeding amount is 100g/min, the spray gun outlet of the plasma spraying equipment rotates and sprays towards the exposed surface of the honeycomb structure, and the angle between the initial spraying direction and the plane where the exposed surface of the honeycomb structure is located is 35 degrees , the included angle changes continuously between 30-150 degrees at a rate of 50 degrees/min, wherein the mesh number of the honeycomb holes of the metal honeycomb base is 600 mesh, the depth of the honeycomb holes is 10mm, and the thickness of the hole walls is less than 1mm, The cross-sectional shape of the honeycomb cells was circular, and the porosity of the obtained catalyst coating was 0.25.

Example 4

The catalyst provided in Example 4 is referred to as Catalyst 4.

The concrete preparation method of described catalyst 2 is:

1. Prepare a catalyst precursor, the catalyst precursor is composed of porous microsphere particles, and the porous microsphere particles are prepared by the following method:

Mix and ball mill nano cerium oxide, palladium chloride, starch and water to a uniform slurry;

The slurry is sprayed and granulated by a spray dryer, and calcined at 500°C for 2 hours to obtain porous microsphere particles of 10-100 microns, the pore diameter of the porous structure is 5-100 nm, and the pore volume is 0.1-0.8 cm ³ /g . Wherein, the content of palladium is 0.5%.

2. Add 20% solid spherical micro-particles to the obtained catalyst precursor to obtain spray powder. The solid spherical micro-particles are consistent with the composition of the porous micro-sphere particles and have a diameter of 10-100 microns, and the spray powder Spraying onto the surface of the metal honeycomb base by plasma spraying equipment, the metal honeycomb base includes a honeycomb structure, and the honeycomb structure includes an exposed surface extending along the radial direction of the honeycomb holes, during this process, The gas flow rate of the plasma spraying equipment is 100L/min, the distance between the spray gun outlet of the plasma spraying equipment and the surface of the metal substrate is 100mm, and the powder feeding rate is 50g/min, the spray gun of the plasma spraying equipment The exit is rotated and sprayed towards the exposed surface of the honeycomb structure, the angle between the initial spraying direction and the plane where the exposed surface of the honeycomb structure is located is 35 degrees, and the included angle is 30 degrees at a rate of 50 degrees/min. Continuous change between -150 degrees, wherein, the mesh number of the honeycomb holes of the metal honeycomb base is 500 mesh, the depth of the honeycomb holes is 8mm, the thickness of the hole walls is less than 1mm, the cross-sectional shape of the honeycomb holes is circular, and the obtained The porosity of the catalyst coating was 0.15.

Experimental example

1. Test the thermal shock shedding rate and ultrasonic shedding rate of catalysts 1-5 respectively

1. Thermal shock shedding rate test

Specifically, the catalysts 1-5 were weighed respectively, and the weighed catalysts 1-5 were put into a muffle furnace and heated at 1100°C for 5 minutes, then directly put into room temperature water to cool, and repeated 10 times, and then the treated The final catalysts 1-5 were weighed, and the weight reduction divided by the coating weight was the coating shedding rate, so as to obtain the thermal shock shedding rate. The shedding rate of each catalyst is shown in Table 1.

2. Ultrasonic shedding rate test

Specifically, the catalysts 1-5 are weighed respectively, the weighed catalysts 1-5 are put into an ethanol solution and ultrasonicated at a frequency of 40KHz for 1h, and then the ultrasonically treated catalysts 1-5 are weighed, The reduced weight divided by the coating weight is the coating shedding rate, so as to obtain the ultrasonic shedding rate. The shedding rate of each catalyst is shown in Table 1.

Table 1

sample Ultrasonic loss rate thermal shock loss rate Catalyst 1 0.305% 1.05% Catalyst 2 0.131% 0.89% Catalyst 3 0.336% 1.25% Catalyst 4 0.148% 1.06% Catalyst 5 11.81% 81.27%

Conclusion: the shedding rate of catalyst 1-4 is significantly lower than that of catalyst 5, indicating that the catalyst coating provided by the embodiment of the present invention has strong adhesion and is not easy to fall off, thereby improving the activity and stability of the metal substrate catalyst. sex.

2. Test the catalytic activity of catalysts 1-5

Catalytic combustion of CH4 was used as the target reaction to evaluate the activity of the catalyst. A small fixed-bed continuous flow reaction device is adopted, and the reaction tube is a quartz tube with an inner diameter of Φ10mm, which is placed in a heating furnace, and the temperature is programmed to control the reaction temperature. The TCD detector of gas chromatograph (SHIMADZU, Model GC-2014) was used for online detection, and the concentration of CH ₄ , N ₂ , O ₂ , CO ₂ was quantitatively analyzed. The methane conversion rate (X) was calculated by the following formula: X=[(A ₀ -A _x )/A ₀ ]×100%. Among them, A ₀ is the chromatographic peak area of methane before the reaction, and A _x is the chromatographic peak area of methane after the reaction at different temperatures.

Specifically, catalysts 1-5 were used to catalyze the combustion reaction of methane at different temperatures, and the conversion rate of methane in each group of reactions was detected respectively. The test results are shown in Table 2.

Table 2

temperature Catalyst 1 Catalyst 2 Catalyst 3 Catalyst 4 Catalyst 5 350°C 12.62% 4.85% 10.18% 4.16% 13.18% 400°C 48.23% 22.14% 44.41% 20.85% 45.88% 450°C 89.11% 59.26% 87.41% 55.70% 84.56% 500℃ 99.79% 87.12% 99.79% 80.91% 98.71%

Conclusion: It can be seen from Table 2 that when the metal-based catalyst obtained by the method provided by the embodiment of the present invention is used for methane combustion, the conversion rate of methane is significantly improved compared with the prior art. It can be seen that the metal substrate catalyst provided by the embodiments of the present invention has better catalytic activity, and the catalyst coating obtained by adding solid microsphere particles has a lower porosity than the catalyst coating obtained by all porous microsphere particles. Small, indicating that the spray powder adopts porous microsphere particles to form a catalyst coating with higher porosity on the surface of the metal substrate, thereby increasing the specific surface area of the catalyst coating and improving the catalytic activity of the metal substrate catalyst to the greatest extent.

In summary, by spraying the catalyst precursor as a spray powder on the surface of the metal substrate by plasma spraying technology, the catalyst precursor is composed of microsphere particles, and the microsphere particles have a porous structure, which can form a firm adhesion For the catalyst coating on the surface of the metal substrate, compared with the dipping method, the preparation process can improve the adhesion of the catalyst coating and reduce shedding, thereby improving the activity and stability of the catalyst. The invention overcomes the defect of poor catalyst coating adhesion in the prior art, resulting in poor activity and stability of the catalyst.

The above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Anyone skilled in the art can easily think of changes or substitutions within the technical scope disclosed in the present invention. Should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (14)

1. A preparation method for a metal substrate catalyst, characterized in that, comprising: The catalyst precursor is sprayed onto the surface of the metal substrate as a spray powder by plasma spraying equipment to form a catalyst coating, wherein the catalyst precursor is composed of microsphere particles, and the microsphere particles have a porous structure; Wherein, the diameter of the microsphere particles is 10-100 microns, the pore diameter of the porous structure is 5-100 nm, and the pore volume is 0.1-0.8 cm ³ /g. 2. The preparation method according to claim 1, wherein the catalyst precursor is prepared through the following steps: Mix and grind the compound containing the catalytically active component, the pore former and the solvent to make a slurry; The slurry is subjected to spray granulation, and calcined at a preset temperature for a preset time. 3. preparation method according to claim 2, is characterized in that, The pore-forming agent is starch or/and polyethylene glycol. 4. preparation method according to claim 2, is characterized in that, The preset temperature is 400-800° C., and the preset time is 2-3 hours. 5. preparation method according to claim 1, is characterized in that, The metal base is a metal honeycomb base. 6. preparation method according to claim 5, is characterized in that, The mesh number of the honeycomb holes of the metal honeycomb base is 100-600, and the thickness of the hole walls is less than 1mm. 7. preparation method according to claim 5, is characterized in that, The metal honeycomb substrate includes a honeycomb structure body, and the honeycomb structure body includes bare surfaces extending along the radial direction of the honeycomb holes. During the spraying process, the spray gun outlet of the plasma spraying equipment is directed toward the The exposed surface of the honeycomb structure is sprayed in rotation, and the angle between the spraying direction of the plasma spraying equipment and the plane where the exposed surface of the honeycomb structure is continuously changed within a preset range. 8. preparation method according to claim 7, is characterized in that, The preset range is 30-150 degrees. 9. preparation method according to claim 7, is characterized in that, The rate of continuous change is 10-50 degrees/min. 10. preparation method according to claim 1, is characterized in that, The method further includes: adding auxiliary spraying powder to the catalyst precursor, and the auxiliary spraying powder is composed of solid microsphere particles. 11. according to the preparation method described in any one of claim 1-10, it is characterized in that, The spraying temperature of the plasma spraying device is lower than the melting point of the catalyst precursor. 12. according to the preparation method described in any one of claim 1-10, it is characterized in that, The powder feeding rate of the plasma spraying equipment is 5-100g/min. 13. A metal substrate catalyst obtained by the preparation method according to any one of claims 1-12, characterized in that, the metal substrate catalyst comprises: a metal substrate and a catalyst coating attached to the surface of the metal substrate. 14. The metal substrate catalyst according to claim 13, characterized in that, The porosity of the catalyst coating is 0.05-0.3.