CN114832866A - Catalytic reformer and shape regulation method and application thereof - Google Patents
Catalytic reformer and shape regulation method and application thereof Download PDFInfo
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- B01J15/00—Chemical processes in general for reacting gaseous media with non-particulate solids, e.g. sheet material; Apparatus specially adapted therefor
- B01J15/005—Chemical processes in general for reacting gaseous media with non-particulate solids, e.g. sheet material; Apparatus specially adapted therefor in the presence of catalytically active bodies, e.g. porous plates
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- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/08—Heat treatment
- B01J37/082—Decomposition and pyrolysis
- B01J37/084—Decomposition of carbon-containing compounds into carbon
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- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/16—Reducing
- B01J37/18—Reducing with gases containing free hydrogen
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- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/32—Freeze drying, i.e. lyophilisation
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- Y02P20/50—Improvements relating to the production of bulk chemicals
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Abstract
The invention discloses a catalytic reformer and a shape regulation and control method and application thereof, and relates to the technical field of preparation of integrated catalysts. It includes: mixing and homogenizing a catalyst carrier and a solution of an active component and a catalyst auxiliary agent of a catalyst to form slurry, so that the active component and the auxiliary agent solution can be uniformly distributed on the surface and the periphery of the carrier, then carrying out three-dimensional printing on the slurry to form a catalytic reformer blank with a specific structure, and then carrying out freeze drying on the blank to enable the active component and the auxiliary agent to be separated out on the surface of the carrier in situ and simultaneously form microscopic holes to increase the specific surface area of the catalyst; the vacuum degreasing is carried out before the air decarbonization is carried out on the freeze-dried blank, so that the decomposition rate of organic substances can be reduced, less gas is generated during the decarbonization, the macro structure of the catalytic reformer is guaranteed to be unchanged, the reduction reaction is finally carried out to form the catalytic reformer with the accurately regulated and controlled formability, the structure of the catalytic reformer is not easy to collapse, and the catalytic activity is excellent.
Description
Technical Field
The invention relates to the technical field of preparation of integrated catalysts, in particular to a catalytic reformer and a shape regulation method and application thereof.
Background
With the development of science and technology, some novel hydrogen production modes such as solar energy and plasma hydrogen production are developed to a certain extent, but chemical hydrogen production is still the main mode of industrial hydrogen production at present. Wherein the hydrogen production by methane steam reforming occupies 80% of the market share, and the hydrogen production efficiency is as high as 70% -90%. The methane steam reforming reaction is a reversible strong endothermic reaction, and in order to improve the methane conversion rate, the catalytic reformer is a key, and the catalyst consists of a catalytic reaction device and a catalyst. The catalyst mainly comprises three parts, namely a catalyst active component, a catalyst carrier and a catalyst auxiliary agent. At present, a catalytic reaction device is generally made of metal alloy, so that the reaction is ensured to be carried out safely, and a catalyst ensures the methane conversion efficiency. However, the catalytic reformer has a complex preparation process, an uncertain gas passage and unstable conversion efficiency.
In view of this, the invention is particularly proposed.
Disclosure of Invention
The present invention aims to provide a catalytic reformer, a shape control method thereof and an application thereof to solve the above technical problems.
The invention is realized by the following steps:
in a first aspect, the present invention provides a method for shape control of a catalytic reformer, comprising:
mixing and homogenizing a dissolving solution of the catalyst active component and the catalyst auxiliary agent with the catalyst carrier to form slurry;
carrying out three-dimensional printing forming on the slurry according to a pre-designed three-dimensional model to obtain a catalytic reformer blank;
freeze-drying and heat-treating the catalytic reformer body, wherein the heat treatment comprises a vacuum degreasing step, an air decarbonization step and a reduction step.
In a second aspect, the present application provides a catalytic reformer manufactured using the shape control method of a catalytic reformer according to any one of the above embodiments.
In a third aspect, the present application provides the use of a catalytic reformer as described in the above embodiments in the production of hydrogen from methane.
The invention has the following beneficial effects:
according to the shape regulation and control method of the catalytic reformer, the catalyst active component, the catalyst auxiliary agent and the catalyst carrier are mixed to form the slurry, and at the moment, the catalyst active component and the catalyst auxiliary agent in the slurry can be uniformly distributed on the surface and the periphery of the catalyst carrier, so that a foundation is provided for subsequent three-dimensional printing and shape regulation and control. The uniform slurry can be directly formed into a catalytic reformer blank by using a three-dimensional printing technology, and at the moment, the whole catalytic reformer blank is formed by printing the slurry and has a complete pipe wall and a complete gas passage, so that a catalytic reaction device in the prior art can be omitted. In the application, the original fixed structure formed by printing is kept by the catalytic reformer through the freezing step in the freeze drying, meanwhile, in the subsequent drying step, the freeze-dried solution in the raw material can be directly sublimated, and meanwhile, the active component and the catalyst auxiliary agent of the catalyst are uniformly separated out on the surface of the catalyst carrier in situ. And then, the vacuum degreasing step is adopted to effectively reduce the decomposition rate of organic substances such as PVA, glycerol and the like so as to ensure that the structure of the catalytic reformer is unchanged, the air decarbonization step gradually removes the organic substances from carbon formed in the vacuum degreasing process so as to ensure that the structure is unchanged and a catalyst precursor is generated, and finally, a reduction reaction is carried out to finally prepare the integrated catalytic reformer, which can be widely applied to methane reforming hydrogen production.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
FIG. 1 is an SEM and EDS image of a catalytic reformer provided in example 3 of the present application;
fig. 2 is a schematic diagram of a catalytic reformer shaped at different 3D printing parameters as provided in experimental example 1 of the present application.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
The invention provides a shape regulating method of a catalytic reformer, which comprises the following steps:
and S1, preparing printing paste.
And mixing and homogenizing the solution of the catalyst active component and the catalyst auxiliary agent and the catalyst carrier to form slurry.
Specifically, the raw materials of the slurry comprise the following components in percentage by volume: 80-90 wt% of catalyst carrier, 1-10 wt% of catalyst active component and 1-10 wt% of catalyst auxiliary agent. For example, 82 to 90 wt% of catalyst carrier, 1 to 10 wt% of catalyst active component and 1 to 10 wt% of catalyst auxiliary agent. For example 85 wt% catalyst support, 10 wt% catalyst active component and 5 wt% catalyst promoter.
In the application, the catalyst active component and the catalyst auxiliary agent are dissolved in advance and completely dissolved in the solvent, so that the uniform distribution of the catalyst active component and the catalyst auxiliary agent during subsequent forming is facilitated. Specifically, the solvent for dissolving the catalyst active component and the catalyst auxiliary may be water only, but the inventors have found through research that water alone is used as the solvent, and in the subsequent printing process, drying cracking may occur. Therefore, in the application, a moisturizing bonding solvent is selected as a solvent for dissolving the catalyst active component and the catalyst auxiliary, wherein the raw materials of the moisturizing bonding solvent comprise water, glycerol and polyvinyl alcohol, the volume ratio of the water to the glycerol is 1-5:1, and the concentration of the polyvinyl alcohol in the moisturizing bonding solvent is 3-5 wt%. Wherein, polyvinyl alcohol (PVA) solution is used as a binder, and the catalyst carrier can be tightly bound into a certain macroscopic structure without collapse. The glycerol and the water can be used as a solvent for dissolving polyvinyl alcohol together, and meanwhile, the glycerol can also be used as a humectant, so that the moisture of the slurry can be kept, and the condition of drying and cracking in the printing process can be effectively avoided. It is noted that polyvinyl alcohol and glycerin as the binder and humectant are provided herein as merely a representative but non-limiting example, and it is understood that other ingredients having a binding effect and a moisturizing effect may be used as the moisturizing binder solvent herein.
Preferably, in the application, the catalyst carrier is added in a manner of adding the dissolving solution in batches, so that the catalyst carrier and the dissolving solution are uniformly mixed, and the catalyst active component and the catalyst auxiliary agent in the dissolving solution are more easily and uniformly distributed on the surface and the periphery of the catalyst carrier. In addition, the present application homogenizes by centrifugation and sonication; the centrifugation and the ultrasonic treatment can be performed once or for multiple times, and in the application, the centrifugation and the ultrasonic treatment are preferably performed for multiple times alternately until the homogenization is complete.
In addition, it is also noted that the catalyst carrier includes, but is not limited to, at least one of alumina, silica gel, activated carbon, etc., the catalyst active component includes, but is not limited to, at least one of Fe, Co, and Ni and noble metals of platinum, palladium, rhodium, silver, ruthenium, and the catalyst auxiliary agent includes, but is not limited to, at least one of calcium oxide, magnesium oxide, lanthanum oxide, cerium oxide, etc. The specific selection of the catalyst carrier, the catalyst active component and the catalyst promoter is not limited in the present application, and the catalyst carrier, the catalyst active component and the catalyst promoter may be selected from conventional catalyst carriers, catalyst active components and catalyst promoters.
And S2, three-dimensional printing and forming.
And (4) carrying out three-dimensional printing and forming on the slurry according to a pre-designed three-dimensional model to obtain a catalytic reformer blank, and finishing primary structure regulation and control.
The specific structure of the green catalytic reformer body is not limited in the present application, and is mainly formed according to a pre-designed three-dimensional model, and the specific structure of the three-dimensional model can be selected according to actual conditions, such as selecting different lengths, different gas flow channels, and the like. In the present application, the three-dimensional printing can be formed in various ways, including but not limited to, at least one of direct ink writing, inkjet printing, and photo-curing.
Preferably, the three-dimensional printing is performed by adopting an ink direct writing mode, and the movement speed of the needle head is 400-1000mm/min, preferably 600-800mm/min, during the ink direct writing. Through Direct Ink Writing (DIW), a target catalytic reformer can be accurately obtained according to a pre-designed three-dimensional model of the catalytic converter, and a gas passage of the catalytic reformer obtained by a 3D printing technology is clear and can be better applied to catalytic reaction. In addition, the structure of the whole catalytic reformer can be accurately regulated and controlled macroscopically by adopting the ink direct writing technology, so that the aerodynamic research of the catalytic reformer can be completed in an early modeling stage, and the structure of the catalytic reformer (including the direction not limited to a pipeline and an air inlet/outlet) can be further adjusted according to a basic research result. And corresponding basic research can be carried out without preparing a catalytic reformer. Meanwhile, the slurry composition selection range of the ink direct writing technology is wide, a specific moisturizing bonding solvent is adopted as a solvent conveniently, and no influence is caused on three-dimensional printing.
S3, shape regulation.
And carrying out freeze drying and heat treatment on the catalytic reformer blank, wherein the heat treatment comprises a vacuum degreasing step, an air decarbonization step and a reduction step.
(1) The freeze drying comprises the following steps: pre-freezing the catalytic reformer blank at-20 to-30 ℃ to keep the macrostructure of the catalytic reformer blank unchanged, then placing the catalytic reformer blank at-60 to-80 ℃, vacuumizing to 0.08MPa to 0.12MPa, and then heating to 10 ℃ to 20 ℃ for sublimation until the catalytic reformer blank is completely dried.
The method adopts freeze drying to fully dry the catalytic reformer body, the catalytic reformer body printed by homogeneous slurry is frozen in the freezing process of freeze drying, the uniform solution is directly converted into ice at the moment, the catalyst active component and the catalyst auxiliary agent are fixed in a solid form, and the structure of the catalytic reformer body is kept unchanged and is not easy to collapse. In the freezing process, the catalyst active component and the catalyst auxiliary agent in the solution are precipitated in situ without segregation, so that the catalyst active component and the catalyst auxiliary agent can be uniformly loaded on the surface of the catalyst carrier, and then the water vapor is directly removed in a direct sublimation mode. Meanwhile, the activity or the catalytic performance of the active components and the catalyst auxiliaries of the catalyst cannot be damaged by freeze drying, the catalytic performance of the catalytic reformer blank can be better maintained, and the secondary structure regulation and the primary performance regulation of the catalytic reformer are realized in the process.
The temperature in the freezing process may be, for example, at least one of-60 ℃, -62 ℃, -67 ℃, -69 ℃, -70 ℃, -72 ℃, -73 ℃, -79 ℃, and 80 ℃, or a range therebetween. The temperature of the sublimation process may be at least one of 10 ℃, 12 ℃, 15 ℃, 19 ℃ and 20 ℃ or a range between any two of them, for example.
(2) The vacuum degreasing comprises the following steps: and placing the catalytic reformer blank subjected to freeze drying treatment in a heat treatment environment for vacuum degreasing to carbonize organic substances in the moisturizing bonding solvent and reduce the decomposition rate of the organic substances, setting the heat treatment environment to raise the temperature to 550-650 ℃ at the temperature raising rate of 2-5 ℃/min, and preserving the heat for 6-7 hours.
Because PVA, glycerin and other organic substances are used in the preparation of the slurry, the decomposition rate of the PVA, the glycerin and other organic substances can be effectively reduced by a slow vacuum degreasing method, so that the structure of the catalytic reformer is ensured to be unchanged. In the vacuum degreasing, the components of the solution for 3D printing, including but not limited to organic substances such as PVA and glycerol, are carbonized, and the decomposition rate of the organic substances is reduced, so that the structure of the catalytic reformer is ensured to be unchanged. If vacuum degreasing is skipped and air decarbonization is directly performed, organic substances such as PVA and glycerin are combusted in the air decarbonization step, a large amount of gas is generated, and the gas easily causes collapse of the catalytic reformer, so that the catalytic reformer fails to be prepared.
(3) The air decarbonization comprises the following steps: and after the vacuum degreasing is finished, filling air into the heat treatment environment of the catalytic reformer blank, raising the temperature of the heat treatment environment to 700-800 ℃ at the heating rate of 2-5 ℃/min, and preserving the heat for 4-5 hours to remove carbon formed in the vacuum degreasing process, thereby finishing the third structural regulation and control of the catalytic reformer. Meanwhile, in the processes of vacuum degreasing and air decarbonization, the active components of the catalyst and the auxiliary agent are subjected to decomposition reaction to generate corresponding oxides, the oxide components are more stably attached to the surface of the catalyst carrier in the process, crystal grains grow initially, and secondary performance regulation and control of the catalytic reformer are completed.
Carbon can be gradually removed in a gradient temperature rise mode, so that the structure of the catalytic reformer is not changed and a catalyst precursor is generated. The air decarbonization is to gradually remove organic matters from carbon formed in the vacuum degreasing process so as to ensure that the structure is not changed and the catalyst precursor is generated.
(4) The reduction comprises the following steps: after the air decarbonization is finished, the green body of the catalytic reformer is continuously placed at 650-850 ℃ for hydrogen reduction for 4-5 hours. The reduction is performed by subjecting the catalytic reformer to reduction in an atmosphere of a reducing gas such as hydrogen. In the high-temperature reduction process, the precursor (namely oxide) of the active component of the catalyst generates a simple substance under the reducing atmosphere, and the third performance regulation and control of the catalytic reformer are completed.
According to the shape control method of the catalytic reformer, the catalyst active component, the catalyst auxiliary and the catalyst carrier are mixed to form the slurry, and at the moment, the catalyst active component and the catalyst auxiliary in the slurry can be uniformly distributed on the surface and the periphery of the catalyst carrier, so that a foundation is provided for subsequent three-dimensional printing and shape control. The uniform slurry can be directly formed into the catalytic reformer blank by adopting a three-dimensional printing technology, the 3D printing forming can complete the preliminary structure regulation, at the moment, the whole catalytic reformer blank is formed by adopting slurry printing and has a complete pipe wall and a gas passage, so that a catalytic reaction device in the prior art can be omitted. In the application, the original fixed macrostructure formed by printing is kept by the catalytic reformer through the freezing step in the freeze drying, meanwhile, the active components and the catalyst auxiliaries of the catalyst are uniformly precipitated on the surface of the catalyst carrier in situ, meanwhile, in the subsequent drying step, the freeze-dried solution in the raw material can be directly sublimated without changing the positions of the active components and the auxiliaries, and in addition, in the freeze-drying process, the catalyst carrier can also keep higher specific surface area and porous structure. And then, adopting a vacuum degreasing step to effectively reduce the decomposition rate of organic substances such as PVA, glycerol and the like so as to ensure that the structure of the catalytic reformer is unchanged, gradually removing organic substances from carbon formed in the vacuum degreasing step in an air decarbonization step so as to ensure that the structure is unchanged and a catalyst precursor is generated, and finally carrying out a reduction reaction to obtain the integrated catalytic reformer with the uniformly-loaded catalyst active component and the uniformly-loaded auxiliary agent. In this application, through 3D printing shaping, freeze-drying and thermal treatment realization to the regulation and control of the shape structure of catalytic reformer, utilize simultaneously to mix thick liquids and freeze-drying in advance, realize the regulation and control to the nature of catalytic reformer, synthesize above-mentioned step and can fully realize the shape regulation and control to catalytic reformer, the catalytic reformer who obtains keeps printing the original fixed knot structure that forms, has good catalytic performance simultaneously.
The present invention also provides a catalytic reformer manufactured by the method for controlling the shape of the catalytic reformer according to any one of the above embodiments. The catalytic reformer has a gas inlet and a gas outlet, so that the gas can be separated conveniently, and in an alternative embodiment, the catalytic reformer can be optionally connected with a gas separation device, a purification device, an exhaust gas collection device and the like.
The invention also provides application of the catalytic reformer in hydrogen production from methane. Including but not limited to methane steam reforming to produce hydrogen.
The features and properties of the present invention are described in further detail below with reference to examples.
Example 1
The embodiment provides a shape regulating method of a catalytic reformer. The method specifically comprises the following steps:
catalytic reformer feedstock preparation: 80 wt% of a catalyst carrier (alumina), 10 wt% of a catalyst active component (Ni) and 10 wt% of a catalyst promoter (magnesia and ceria);
preparation of catalytic reformer slurry: completely dissolving the nitrate of the catalyst active component and the catalyst auxiliary agent in a moisture-preserving binding solvent, wherein the moisture-preserving binding solvent is a mixed solution of PVA, glycerol and water, the concentration of the PVA in the moisture-preserving binding solvent is 3 wt%, and the volume ratio of the water to the glycerol is 1: 1. Then adding the catalyst carrier into the solution in 2 batches, and alternately carrying out high-speed centrifugal mixing and ultrasonic treatment until the slurry is completely homogenized.
And (3) forming the catalytic reformer: the catalyst is formed by adopting an ink direct writing (DIW) technology according to a pre-designed three-dimensional model of the catalyst, and the movement speed of a needle head is 700 mm/min.
Drying of the catalytic reformer: drying the catalytic reformer blank by adopting a freeze drying technology; the method comprises the steps of pre-freezing a formed blank in a refrigerator to ensure that the structure of the formed blank is unchanged initially, setting the temperature of a freeze dryer at-60 ℃, putting the blank into the frozen blank, vacuumizing the blank to 0.1MPa, and heating the freeze dryer to 10 ℃ until the blank is completely dried, wherein the total freeze-drying time is not more than 48 hours.
Heat treatment of the catalytic reformer: the catalytic reformer is subjected to heat treatment in three steps, firstly, the temperature is raised to 600 ℃ at 2 ℃, the temperature is kept for 6 hours, and vacuum degreasing is carried out; then charging air, raising the temperature to 700 ℃ at 2 ℃, preserving the heat for 4 hours, and removing carbon from the air; finally, hydrogen is reduced for 4 hours at 800 ℃ to obtain the integrated catalytic reformer.
Example 2
The embodiment provides a shape regulating method of a catalytic reformer. The method specifically comprises the following steps:
catalytic reformer feedstock preparation: 85 wt% of catalyst carrier (alumina), 10 wt% of catalyst active component (platinum) and 5 wt% of catalyst promoter (lanthanum oxide).
Preparation of catalytic reformer slurry: completely dissolving nitrates of the catalyst active component and the catalyst auxiliary agent in a moisturizing bonding solvent, wherein the moisturizing bonding solvent is a mixed solution of PVA, glycerol and water, the concentration of the PVA in the moisturizing bonding solvent is 4 wt%, and the volume ratio of the water to the glycerol is 1.2: 1; then adding the catalyst carrier into the solution in batches, and alternately carrying out high-speed centrifugal mixing and ultrasonic treatment until the slurry is completely homogenized.
And (3) forming the catalytic reformer: forming the catalyst by adopting an ink direct writing (DIW) technology according to a pre-designed three-dimensional model of the catalyst, wherein the movement speed of a needle head is 400 mm/min;
drying of the catalytic reformer: drying the catalytic reformer blank by adopting a freeze drying technology; pre-freezing a formed blank in a refrigerator to ensure that the structure of the formed blank is unchanged initially, setting the temperature of a freeze dryer at-70 ℃, putting the frozen blank into the refrigerator, vacuumizing the refrigerator to a value of 0.1MPa, and heating the freeze dryer to a temperature of 15 ℃ until the blank is completely dried, wherein the total freeze-drying time is not more than 48 hours;
heat treatment of the catalytic reformer: the catalytic reformer is subjected to heat treatment in three steps, firstly, the temperature is raised to 600 ℃ at 3 ℃, the temperature is kept for 6 hours, and vacuum degreasing is carried out; then charging air, heating to 750 ℃ at 3 ℃, preserving heat for 4 hours, and removing carbon by the air; finally, hydrogen is reduced for 4 hours at 800 ℃ to obtain the integrated catalytic reformer.
Example 3
The embodiment provides a shape regulating method of a catalytic reformer. The method specifically comprises the following steps:
catalytic reformer feedstock preparation: 85 wt% of catalyst carrier (alumina), 10 wt% of catalyst active component (Ni) and 5 wt% of catalyst promoter (magnesia and ceria).
Preparation of catalytic reformer slurry: completely dissolving nitrates of the catalyst active component and the catalyst auxiliary agent in a moisturizing bonding solvent, wherein the moisturizing bonding solvent is a mixed solution of PVA, glycerol and water, the concentration of the PVA in the moisturizing bonding solvent is 5 wt%, and the volume ratio of the water to the glycerol is 1: 1; then adding the catalyst carrier into the solution in batches, and alternately carrying out high-speed centrifugal mixing and ultrasonic treatment until the slurry is completely homogenized.
And (3) forming the catalytic reformer: the catalyst is formed by adopting an ink direct writing (DIW) technology according to a pre-designed three-dimensional model of the catalyst, and the movement speed of a needle head is 700 mm/min.
Drying of the catalytic reformer: drying the catalytic reformer blank by adopting a freeze drying technology; pre-freezing a formed blank in a refrigerator to ensure that the structure of the formed blank is unchanged initially, setting the temperature of a freeze dryer at-80 ℃, putting the frozen blank into the refrigerator, vacuumizing the refrigerator to a value of 0.1MPa, and heating the freeze dryer to a temperature of 20 ℃ until the blank is completely dried, wherein the total freeze-drying time is not more than 48 hours;
heat treatment of the catalytic reformer: the catalytic reformer is subjected to heat treatment in three steps, firstly, the temperature is raised to 600 ℃ at 3 ℃, the temperature is kept for 6 hours, and vacuum degreasing is carried out; then charging air, heating to 800 ℃ at 4 ℃, preserving heat for 4 hours, and removing carbon by the air; finally, hydrogen is reduced for 4 hours at 800 ℃ to obtain the integrated catalytic reformer.
Referring to fig. 1, it can be seen from the SEM image of fig. 1 that nanoparticles are attached to the surface of the large irregular particles, and the size of the large particles is about 200 μm, which is consistent with the size of the catalyst sieve. The simple substance Ni is obtained by separating out nickel nitrate from the solution, calcining and reducing, so the size is extremely small. According to the EDS results, Ni is uniformly distributed on the surface of alumina as shown in (a) of fig. 1. As can be seen from (b) and (c) of fig. 1, nanoparticles are also attached to the surface of irregular macroparticles, and as can be seen from the EDS of fig. 1, Ni is uniformly distributed on the surface of the alumina particles, and at the same time, Mg and Ce are also distributed at the positions where Ni is distributed. The catalyst prepared by the method has the advantages that the active components and the auxiliary agent of the catalyst are uniformly loaded on the surface of the carrier, and the positions of the auxiliary agent and the active components of the catalyst are consistent, so that the active components of the catalyst can fully play the roles in the subsequent catalytic evaluation process.
Comparative example 1
The only difference compared to example 1 is that the catalytic reformer freeze-drying step, without vacuum drying, was carried out directly with hot air drying at 120 ℃.
Experimental example 1
The method provided in example 1 was used to prepress a catalytic reformer with microchannels having circular cross-sections, diameters of 300 μm, 400 μm, 500 μm and 600 μm, respectively, and channel lengths of 6000 μm, under different 3D printing parameters.
As shown in FIG. 2, in which (a) in FIG. 2 is a needle movement speed of 400mm/min, it can be seen that the through-holes having a diameter of 300 μm were clogged, the through-holes having a diameter of 400 to 600 μm were not clogged, and the actual diameters were 230, 330 and 450 μm, respectively. The movement speed of the needle in fig. 2 (b) is 700mm/min, and it can be seen that no blockage occurs to the through holes with the diameters of 300-600 μm, the actual through holes with the diameters of 160 μm, 300 μm, 400 μm and 500 μm, and the forming holes are all in micron order, which indicates that the 3D printing method provided by the embodiment 1 of the present application has high precision and is not easy to block.
Experimental example 2
A catalytic reformer was prepared and characterized according to the methods of example 1 and comparative example 1, and the characterization results were as follows:
wherein 0# represents no auxiliary Mg/Ce, and 2# represents that the content of Mg/Ce is 5 wt%.
As can be seen from the above results, in example 1 of the present application, the data of 0# Ni-Al, 2# Mg-Ni and 2# Ce-Ni can be combined with γ -Al by freeze-drying 2 O 3 Compared with the specific surface area, the porosity and the pore size are slightly reduced. While comparative example 1 adopts hot air drying, data of 0# Ni-Al, 2# Mg-Ni and 2# Ce-Ni and gamma-Al 2 O 3 Compared with the specific surface area, the porosity and the pore size are obviously reduced.
In summary, the method for regulating the shape of the catalytic reformer provided by the application forms the slurry by mixing the catalyst active component, the catalyst auxiliary agent and the catalyst carrier, and at this time, the catalyst active component and the catalyst auxiliary agent in the slurry can be uniformly distributed on the surface and the periphery of the catalyst carrier, so that a basis is provided for the subsequent three-dimensional printing and shape regulation. The uniform slurry can be directly formed into a catalytic reformer blank by using a three-dimensional printing technology, and at the moment, the whole catalytic reformer blank is formed by printing the slurry and has a complete pipe wall and a complete gas passage, so that a catalytic reaction device in the prior art can be omitted. The original fixed structure formed by printing is kept by the catalytic reformer through the freezing step in the freeze drying process, meanwhile, the active components and the catalyst auxiliaries of the catalyst are uniformly separated out on the surface of the catalyst carrier in situ, meanwhile, in the subsequent drying step, the freeze-dried solution in the raw material can be directly sublimated without changing the positions of the active components and the auxiliaries, and in addition, in the freeze-drying process, the catalyst carrier can also keep a higher specific surface area and a porous structure. And then, the vacuum degreasing step is adopted to effectively reduce the decomposition rate of organic substances such as PVA, glycerol and the like so as to ensure that the structure of the catalytic reformer is unchanged, the air decarbonization step gradually removes the organic substances from carbon formed in the vacuum degreasing process so as to ensure that the structure is unchanged and a catalyst precursor is generated, finally, reduction reaction is carried out, and finally, the integrated catalytic reformer is prepared and obtained, and can be widely applied to methane hydrogen production.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A method of shape management for a catalytic reformer, comprising:
mixing and homogenizing a dissolving solution of the catalyst active component and the catalyst auxiliary agent with the catalyst carrier to form slurry;
carrying out three-dimensional printing forming on the slurry according to a pre-designed three-dimensional model to obtain a catalytic reformer blank;
freeze-drying and heat-treating the catalytic reformer body, wherein the heat treatment comprises a vacuum degreasing step, an air decarbonization step and a reduction step.
2. The method for controlling the shape of a catalytic reformer according to claim 1, wherein the solution is prepared by dissolving the catalyst active component and the catalyst promoter in a moisturizing binding solvent, wherein raw materials of the moisturizing binding solvent include water, glycerol and polyvinyl alcohol, a volume ratio of the water to the glycerol is 1-5:1, and a concentration of the polyvinyl alcohol in the moisturizing binding solvent is 3-5 wt%;
preferably, the catalyst support is added to the dissolution liquid in portions, homogenized by centrifugation and sonication;
preferably, centrifugation and sonication are performed alternately a plurality of times until homogenization is complete;
preferably, the raw materials of the slurry comprise, by volume percent: 80-90 wt% of catalyst carrier, 1-10 wt% of catalyst active component and 1-10 wt% of catalyst auxiliary agent.
3. A method of shape modification of a catalytic reformer in accordance with claim 1, characterized in that the freeze-drying comprises: and placing the blank body of the catalytic reformer in a freeze dryer, vacuumizing to 0.08MPa-0.12MPa at the temperature of-60 ℃ to-80 ℃, and heating to 10 ℃ to 20 ℃ for sublimation until the blank body of the catalytic reformer is completely dried.
4. A method of shape control of a catalytic reformer in accordance with claim 1, characterized in that the freeze-drying further comprises: before the catalytic reformer blank is placed at the temperature of minus 60 ℃ to minus 80 ℃, the catalytic reformer blank is pre-frozen at the temperature of minus 20 ℃ to minus 30 ℃ so as to ensure the integrity of the macrostructure of the reformer blank.
5. A method of shape modification of a catalytic reformer in accordance with claim 1, wherein the vacuum degreasing comprises: and placing the catalytic reformer blank subjected to freeze drying treatment in a heat treatment environment for vacuum degreasing to carbonize organic substances in the slurry so as to reduce the decomposition rate of the organic substances, setting the heat treatment environment to heat to 550-650 ℃ at the heating rate of 2-5 ℃/min, and preserving heat for 6-7 hours.
6. A method of shape modification of a catalytic reformer in accordance with claim 1, wherein the decarbonizing of the air comprises: and after the vacuum degreasing is finished, filling air into the heat treatment environment of the catalytic reformer blank, raising the temperature of the heat treatment environment to 700-800 ℃ at the temperature rise rate of 2-5 ℃/min, and preserving the heat for 4-5 hours to remove carbon formed in the vacuum degreasing process.
7. A method of shape modification of a catalytic reformer in accordance with claim 1, characterized in that the reducing comprises: and after the air decarbonization is finished, continuously placing the catalytic reformer blank at 650-850 ℃ for hydrogen reduction for 4-5 hours.
8. A shape regulating method of a catalytic reformer in accordance with any one of claims 1 to 7, characterized in that the three-dimensional printing shaping comprises at least one of direct ink writing, inkjet printing and photo-curing.
9. A catalytic reformer characterized by being produced by the method for controlling the shape of a catalytic reformer according to any one of claims 1 to 8.
10. Use of a catalytic reformer according to claim 9 in the production of hydrogen by reforming methane.
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