An integral hydrogen catalytic combustion catalyst and its preparation method and application

Abstract

The present invention relates to the technical field of hydrogen catalytic combustion catalysts, and in particular to a monolithic hydrogen combustion catalyst and its preparation method and application. The preparation method comprises the following steps: S1, placing a metal skeleton in a citric acid solution or a gallic acid solution, hydrothermally reacting, and obtaining a supported metal skeleton having a nanosheet morphology on the surface; S2, impregnating an active component onto the supported metal skeleton obtained in step S1 to obtain a catalyst precursor; S3, the obtained catalyst precursor is calcined and reduced to obtain a monolithic hydrogen combustion catalyst having an active component content of 0.1-0.5%. The present invention adopts a specific organic acid to carry out a hydrothermal reaction and adopts an isometric impregnation method to uniformly load the active component on the metal skeleton, and the formed monolithic hydrogen combustion catalyst has a large specific surface area and strong catalytic activity.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen catalytic combustion, and in particular to an integral hydrogen combustion catalyst and a preparation method and application thereof. Background Art

[0002] Traditional catalysts have problems such as large bed pressure drop, uneven distribution of reactants on the surface of catalyst particles, and large temperature gradients at various points in the catalyst bed. The monolithic hydrogen combustion catalysts with parallel channels developed in the past decade have a high-specific surface area coating on their surface and have strong mechanical strength and can be used in exhaust gas purification or catalytic combustion. Among them, catalytic combustion hydrogen technology is considered to be the most advantageous technology for solving hydrogen emissions. It is not only safe and efficient, but also has unique advantages for low-concentration hydrogen / air mixtures.

[0003] At present, hydrogen catalytic combustion catalysts are mainly divided into precious metal (such as Pd, Pt and Au, etc.) and transition metal (such as Mn, Co and Cu, etc.) catalysts. Among them, precious metals Pd and Pt have the best activity, good low-temperature activity, and can be activated at room temperature, but they are expensive and have high preparation costs. One idea is to reduce the loading amount by increasing the dispersion. In addition, the hydrogen catalytic combustion catalysts currently under research are mainly powder catalysts. Due to the limited mass transfer / heat transfer performance of this type of catalyst, the heat in the reaction process cannot be removed in time, and it is very easy to form "hot spots" inside the bed, resulting in safety problems such as sintering deactivation of the catalyst and "flying temperature" of the bed. At the same time, under high-throughput operating conditions, powder catalysts generally need to be formed to reduce the pressure drop of the bed. This operation will also lead to a series of problems such as a decrease in the utilization rate of the catalyst active sites.

[0004] In response to the above problems, some researchers have also conducted some explorations. Fernández et al. used foamed SiC with excellent mass transfer / heat transfer properties as a carrier, coated its surface with a layer of Ce-modified Al2O3 coating, dried and calcined it, and then impregnated it with a Pt loading of 0.25%. The experiment showed that the catalyst had good low-temperature activity. At a concentration of 3.3 vol% H2, T 50 The temperature at which the catalyst is heated (conversion rate 50%) is only 32°C (Appl. Catal. B, 2016, 180, 336). While the use of a structural support significantly improves mass and heat transfer, thereby further enhancing catalytic activity, the Al2O3 coating of the catalyst prepared by this method and the SiC support exhibit a weak bond strength. Over extended use, this coating can detach and clog the reaction tubes.

[0005] It's worth noting that monolithic catalysts based on monolithic metals possess a unique three-dimensional open network structure, high thermal conductivity, and mechanical strength, which contribute to efficient mass and heat transfer. Furthermore, radial mixing improves the contact efficiency between active components and reactants. Currently, research on monolithic catalysts for hydrogen combustion reactions is limited. Developing a monolithic catalyst that combines excellent hydrogen combustion catalytic performance with both mass and heat transfer properties would be highly competitive. Summary of the Invention

[0006] Therefore, the technical problem to be solved by the present invention is to overcome the above-mentioned problems existing in the hydrogen combustion catalyst in the prior art, thereby providing an integral hydrogen combustion catalyst and a preparation method and application thereof.

[0007] To this end, the present invention provides the following technical solutions:

[0008] The present invention provides a method for preparing an integral hydrogen combustion catalyst, comprising the following steps:

[0009] S1, placing the metal skeleton in a citric acid solution or a gallic acid solution for hydrothermal reaction to obtain a supported metal skeleton with a nanosheet morphology on the surface;

[0010] S2, impregnating the active component into the supported metal skeleton prepared in step S1 to obtain a catalyst precursor;

[0011] S3, calcining and reducing the obtained catalyst precursor to obtain a monolithic hydrogen combustion catalyst.

[0012] Optionally, in step S1, the temperature of the hydrothermal reaction is 80-200° C., and the time of the hydrothermal reaction is 1-48 hours.

[0013] Optionally, in step S1, the molar concentration of the citric acid solution is 0.001-1 mol / L;

[0014] The molar concentration of the gallic acid solution is 0.001-1 mol / L.

[0015] Optionally, in step S1, the ratio of the metal skeleton to the citric acid solution is 0.001-1 g / mL;

[0016] The usage ratio of the metal skeleton to the gallic acid solution is 0.001-1 g / mL.

[0017] Optionally, in step S2, impregnation is performed using an equal volume impregnation method;

[0018] And / or, the active component includes at least one of platinum element or palladium element.

[0019] Optionally, in step S3, the calcination temperature is 200-600° C., and the calcination time is 0.5-24 h;

[0020] And / or, the calcination is performed in an oxygen-containing atmosphere. Typically, but not limited to, the oxygen-containing atmosphere is air atmosphere.

[0021] Optionally, the reduction temperature is 200-600° C., and the reduction time is 0.5-24 h;

[0022] And / or, the reducing atmosphere is hydrogen or a hydrogen-nitrogen mixture.

[0023] Optionally, the material of the metal skeleton carrier is any one of nickel, iron, cobalt, copper, magnesium, and aluminum;

[0024] And / or, the morphological structure of the metal skeleton carrier is selected from any one of wire mesh, foam, fiber, fiber felt, round tube, and round disc;

[0025] Optionally, the metal skeleton carrier is selected from one of foam nickel, foam copper, foam iron, fiber copper, fiber felt copper, wire mesh nickel, and wafer nickel;

[0026] And / or, the metal skeleton is pre-treated by cleaning with an acidic solution.

[0027] The present invention also provides a monolithic hydrogen combustion catalyst prepared by the above-mentioned preparation method.

[0028] Optionally, the mass percentage of active components in the integral hydrogen combustion catalyst is 0.1-0.5%.

[0029] The present invention also provides an application of the above-mentioned integral hydrogen combustion catalyst in hydrogen combustion;

[0030] Optionally, the hydrogen combustion reaction temperature is 25-150°C, and the space velocity is 1000-50000 mL g -1 h -1 .

[0031] In the present invention, there is no special requirement for the source of the active component. For example, the platinum element can be provided by at least one of platinum nitrate, platinum chloride, platinum acetate, chloroplatinic acid, ammonium chloroplatinate, sodium chloroplatinate or potassium chloroplatinate.

[0032] Optionally, the palladium element can be provided by at least one of palladium nitrate, palladium chloride, palladium acetate, chloropalladic acid, ammonium chloropalladate, sodium chloropalladate or potassium chloropalladate.

[0033] The technical solution of the present invention has the following advantages:

[0034] The present invention provides a method for preparing a monolithic hydrogen combustion catalyst, comprising the following steps: S1, placing a metal skeleton in a citric acid solution or a gallic acid solution for a hydrothermal reaction to obtain a supported metal skeleton having a nanosheet morphology on the surface; S2, impregnating the supported metal skeleton obtained in step S1 with an active component to obtain a catalyst precursor; S3, calcining and reducing the obtained catalyst precursor to obtain a monolithic hydrogen combustion catalyst. The preparation method provided by the present invention forms a complex with the metal ions dissolved from the metal skeleton by citric acid or gallic acid under a hydrothermal environment. Under the hydrothermal action, nanosheet-shaped nickel citrate or nickel gallate grows in a directional manner on the surface of the metal skeleton. This method can significantly increase the specific surface area of ​​the metal skeleton support. Subsequently, the active component is introduced by an impregnation method, and after calcination and reduction, a monolithic hydrogen combustion catalyst with a large specific surface area and strong activity is formed. Compared with the prior art method of preparing a monolithic ammonia decomposition catalyst using raw materials such as urea and ammonium fluoride to form a nanosheet morphology, the catalyst obtained by the technical solution of the present invention has a larger specific surface area and is more environmentally friendly. In addition, the catalyst precursor formed with the monolithic metal as the skeleton carrier has excellent thermal conductivity, which makes the bed temperature evenly distributed, avoiding the sintering and deactivation of active components due to local excessive temperature during calcination.

[0035] The method for preparing the integral hydrogen combustion catalyst provided by the present invention has the advantages of simple process, strong controllability of the preparation process, ease of large-scale production, and highly dispersed and stable active components that are not easy to fall off.

[0036] The monolithic hydrogen combustion catalyst provided by the present invention comprises 0.1-0.5% of an active component, with the remainder being a metal skeleton. The monolithic hydrogen combustion catalyst provided by the present invention utilizes a monolithic metal as a skeleton carrier, with the active component uniformly dispersed on a nanosheet array supported on the surface of the metal skeleton. The resulting monolithic hydrogen combustion catalyst exhibits excellent mass transfer performance, resulting in uniform fluid distribution under high-throughput conditions. This avoids turbulence, channeling, and gas short-circuiting common in traditional particle catalysts, preventing safety issues such as "heat runaway" during the reaction process and significantly improving the utilization rate of the active component.

[0037] The monolithic hydrogen combustion catalyst provided by the present invention has a large specific surface area and a high active component loading, and can efficiently catalyze hydrogen combustion and improve the hydrogen conversion rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0039] Figure 1 This is a scanning electron microscope (SEM) image of the metal skeleton copper foam in Example 1 of the present invention;

[0040] Figure 2 This is a scanning electron microscope (SEM) image of the monolithic hydrogen combustion catalyst prepared in Example 1 of the present invention;

[0041] Figure 3 This is a scanning electron microscope (SEM) image of the metal skeleton foam iron in Example 5 of the present invention;

[0042] Figure 4 is a scanning electron microscope (SEM) image of the monolithic hydrogen combustion catalyst prepared in Example 5 of the present invention;

[0043] Figure 5 This is a graph showing the mass loss of the catalyst of Example 5 after ultrasonic treatment. DETAILED DESCRIPTION

[0044] The following examples are provided for a better understanding of the present invention and are not intended to limit the best mode of implementation. They do not limit the content and scope of protection of the present invention. Any product identical or similar to the present invention obtained by anyone under the guidance of the present invention or by combining the features of the present invention with other prior arts shall fall within the scope of protection of the present invention.

[0045] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in this field can be used. If the manufacturer of the reagents or instruments is not specified, they are all commercially available conventional reagents.

[0046] Example 1

[0047] The present invention provides a method for preparing a monolithic hydrogen combustion catalyst. The specific steps and parameters are as follows:

[0048] At room temperature, 1 g of copper foam (porosity 100 PPI) was ultrasonically treated in a dilute hydrochloric acid solution (molar concentration 0.01 mol / L, the same below) for 10 min to remove the surface copper oxide layer, then washed with distilled water and dried;

[0049] 0.96 g of citric acid was dissolved in 50 ml of distilled water, and the resulting solution was transferred into an autoclave. 1 g of cleaned copper foam was placed in the solution and kept at 120°C for 10 hours. After cooling, the foam was removed, washed with distilled water, and dried to obtain a supported metal skeleton with a nanosheet morphology on the surface.

[0050] 0.4 g of a palladium nitrate aqueous solution containing 0.01 g / g of palladium was weighed and an equal volume of 1 g of a metal skeleton with a nanosheet morphology on the surface was impregnated at room temperature. The metal skeleton was calcined at 300°C for 2 hours in an air atmosphere, and finally reduced at 300°C for 3 hours in a hydrogen-nitrogen mixed gas atmosphere (hydrogen gas volume fraction 2%) to obtain an integral hydrogen combustion catalyst.

[0051] Figure 1 This is the SEM image of the metal skeleton copper foam. Figure 2 This is a SEM image of the monolithic hydrogen combustion catalyst prepared in Example 1. Comparison shows that Example 1 successfully grew nanosheets on the smooth metal skeleton surface via a hydrothermal method. Inductively coupled plasma atomic emission spectroscopy (ICP) characterization determined the Pd content of the catalyst prepared in this example to be 0.49% by weight, demonstrating that the active component was successfully loaded onto the metal skeleton surface with a nanosheet morphology via the isovolumetric impregnation method.

[0052] Example 2

[0053] The present invention provides a method for preparing a monolithic hydrogen combustion catalyst. The specific steps and parameters are as follows:

[0054] At room temperature, 1 g of copper fiber (100 μm in diameter) was ultrasonically treated in a dilute hydrochloric acid solution for 5 min to remove the surface copper oxide layer, then washed with distilled water and dried;

[0055] 0.96 g of citric acid was dissolved in 50 ml of distilled water, and the resulting solution was transferred into an autoclave. 1 g of cleaned copper fiber was placed in the solution and kept at 100°C for 24 hours. After cooling, the fiber was taken out, washed with distilled water, and dried to obtain a supported metal skeleton with a nanosheet morphology on the surface.

[0056] 0.2 g of an aqueous platinum nitrate solution containing 0.02 g / g of platinum was weighed and used to impregnate 1 g of a metal skeleton with a nanosheet surface morphology at equal volume at room temperature. The resulting mixture was calcined at 350°C for 6 hours in an air atmosphere and finally reduced at 400°C for 4 hours under hydrogen to obtain a monolithic hydrogen combustion catalyst.

[0057] The Pt content was measured by inductively coupled plasma atomic emission spectroscopy (ICP). In the catalyst prepared in this example, the mass content of the active component Pt was 0.49%.

[0058] Example 3

[0059] The present invention provides a method for preparing a monolithic hydrogen combustion catalyst. The specific steps and parameters are as follows:

[0060] At room temperature, 1 g of fiber felt copper (thickness 2 mm) was ultrasonically treated in a dilute hydrochloric acid solution for 10 min to remove the surface copper oxide layer, then washed with distilled water and dried;

[0061] 0.96 g of citric acid was dissolved in 50 ml of distilled water, and the resulting solution was transferred into an autoclave. 1 g of cleaned fiber felt copper was placed in the solution and kept at 140°C for 12 hours. After cooling, the fiber felt was taken out, washed with distilled water, and dried to obtain a supported metal skeleton with a nanosheet morphology on the surface.

[0062] 0.1 g of a platinum chloride aqueous solution containing 0.02 g / g of platinum and 0.2 g of a palladium chloride aqueous solution containing 0.01 g / g of palladium were weighed and diluted to 0.5 g. 1 g of a metal skeleton with a nanosheet morphology on the surface was impregnated with equal volumes at room temperature. The mixture was calcined at 350°C for 2 hours in an air atmosphere and finally reduced at 350°C for 6 hours under ammonia to obtain a monolithic hydrogen combustion catalyst.

[0063] The Pt content and the Pd content were measured by inductively coupled plasma atomic emission spectroscopy (ICP). In the catalyst prepared in this example, the mass content of the active component Pd was 0.24%, and the mass content of the active component Pt was 0.25%.

[0064] Example 4

[0065] The present invention provides a method for preparing a monolithic hydrogen combustion catalyst. The specific steps and parameters are as follows:

[0066] At room temperature, 1 g of nickel foam (porosity 100 PPI) was ultrasonically treated in a dilute hydrochloric acid solution for 10 min to remove the surface nickel oxide layer, then washed with distilled water and dried;

[0067] At room temperature, 0.85 g of gallic acid was dissolved in 50 ml of distilled water. After stirring and dissolving completely, the solution was transferred to an autoclave. 1 g of cleaned nickel foam was placed in the solution and kept at 140°C for 12 hours. After cooling, the foam was removed, washed with distilled water, and dried to obtain a supported metal skeleton with a nanosheet morphology on the surface.

[0068] 0.4 g of a palladium acetate aqueous solution containing 0.01 g / g of palladium was weighed and an equal volume of 1 g of a metal skeleton with a nanosheet morphology on the surface was impregnated at room temperature. The mixture was calcined at 550°C for 2 hours in an air atmosphere, and finally reduced at 400°C for 3 hours in a hydrogen-nitrogen mixed gas atmosphere (hydrogen gas volume fraction 2%) to obtain an integral hydrogen combustion catalyst.

[0069] The Pd content was measured by inductively coupled plasma atomic emission spectroscopy (ICP). In the catalyst prepared in this example, the mass content of the active component Pd was 0.49%, indicating that the active component was successfully loaded on the surface of the metal skeleton with nanosheet morphology by the equal volume impregnation method.

[0070] Example 5

[0071] The present invention provides a method for preparing a monolithic hydrogen combustion catalyst. The specific steps and parameters are as follows:

[0072] At room temperature, 1 g of iron foam (100 PPI) was ultrasonically treated in a dilute hydrochloric acid solution for 5 min to remove the surface nickel oxide layer, then washed with distilled water and dried;

[0073] At room temperature, 0.85 g of gallic acid was dissolved in 50 ml of distilled water. After stirring and dissolving completely, the solution was transferred to an autoclave. 1 g of cleaned wire mesh nickel was placed in the solution and kept at 160°C for 12 hours. After cooling, the solution was removed, washed with distilled water, and dried to obtain a supported metal skeleton with a nanosheet morphology on the surface.

[0074] 0.2 g of an aqueous solution of platinum acetate containing 0.02 g / g of platinum was weighed and diluted with water to 0.5 g. An equal volume of a metal skeleton with a nanosheet morphology on the surface of 1 g was impregnated with the solution at room temperature. The solution was calcined at 400°C for 2 hours in an air atmosphere, and finally reduced at 450°C for 4 hours in a hydrogen-nitrogen mixed gas atmosphere (hydrogen gas volume fraction 2%) to obtain an integral hydrogen combustion catalyst.

[0075] Figure 3 The surface of the foam iron metal skeleton carrier, Figure 4 This is an SEM image of the monolithic hydrogen combustion catalyst prepared in Example 5. By comparison, it can be seen that Example 5 successfully grew nanosheets on the smooth metal skeleton support surface via a hydrothermal method. Inductively coupled plasma atomic emission spectroscopy (ICP) characterization determined the Pt content, revealing a Pt content of 0.48% by weight, the active component, in the catalyst prepared in this example.

[0076] Example 6

[0077] The present invention provides a method for preparing a monolithic hydrogen combustion catalyst. The specific steps and parameters are as follows:

[0078] At room temperature, 1 g of nickel disc (8 mm diameter, 2 mm thickness) was ultrasonically treated in dilute hydrochloric acid solution for 10 min to remove the surface nickel oxide layer, then washed with distilled water and dried;

[0079] At room temperature, 0.85 g of gallic acid was dissolved in 50 ml of distilled water. After stirring and dissolving completely, the solution was transferred to an autoclave. 1 g of cleaned nickel discs were placed in the solution and kept at 160°C for 16 hours. After cooling, the solution was removed, washed with distilled water, and dried to obtain a supported metal skeleton with a nanosheet morphology on the surface.

[0080] 0.1 g of a chloroplatinic acid aqueous solution containing 0.02 g / g of platinum and 0.2 g of a chloropalladic acid aqueous solution containing 0.01 g / g of palladium were weighed and diluted to 0.5 g. 1 g of a metal skeleton with a nanosheet morphology on the surface was impregnated with equal volumes at room temperature. The mixture was calcined at 500°C for 3 hours in an air atmosphere, and finally reduced at 450°C for 4 hours in a hydrogen-nitrogen mixed gas atmosphere (hydrogen gas volume fraction 2%) to obtain an integral hydrogen combustion catalyst.

[0081] The Pt content and the Pd content were measured by inductively coupled plasma atomic emission spectroscopy (ICP). In the catalyst prepared in this example, the mass content of the active component Pd was 0.26%, and the mass content of the active component Pt was 0.24%.

[0082] Comparative Example 1

[0083] The comparative example of the present invention provides a method for preparing an integral hydrogen combustion catalyst, and the specific steps and parameters are as follows:

[0084] At room temperature, 1 g of foamed iron (porosity 100 PPI) was ultrasonically treated in a dilute hydrochloric acid solution for 10 min to remove the surface iron oxide layer, then washed with distilled water and dried.

[0085] Weigh 0.2 g of an aqueous solution of platinum nitrate containing 0.02 g / g of platinum and dilute it to 1 g with water. Immerse the cleaned foamed iron support in the solution at room temperature to allow a galvanic replacement reaction between the iron on its surface and the platinum ions in the platinum nitrate solution. After reacting in a 50°C water bath for 2 hours, wash with distilled water and dry to obtain a catalyst precursor.

[0086] The prepared catalyst precursor was calcined at 400° C. for 2 hours in an air atmosphere, and finally reduced at 450° C. for 4 hours in a hydrogen-nitrogen mixed gas atmosphere (hydrogen gas volume fraction 2%) to prepare a monolithic hydrogen combustion catalyst.

[0087] The Pt content of the catalyst can be measured by inductively coupled plasma atomic emission spectroscopy (ICP) characterization, and the mass content of the active component Pt is 0.49%.

[0088] Comparative Example 2

[0089] The comparative example of the present invention provides a method for preparing an integral hydrogen combustion catalyst, and the specific steps and parameters are as follows:

[0090] At room temperature, 1 g of nickel foam (porosity 100 PPI) was ultrasonically treated in a 0.1 mol / L dilute hydrochloric acid solution for 2 hours to etch the surface of the support with dilute hydrochloric acid to increase the specific surface area. The support was then washed with distilled water and dried.

[0091] 0.4 g of a palladium acetate aqueous solution containing 0.01 g / g of palladium was weighed and used to impregnate 1 g of the treated nickel foam support with an equal volume at room temperature; the support was calcined at 550° C. for 2 hours in an air atmosphere, and finally reduced at 400° C. for 3 hours in a hydrogen-nitrogen mixed gas atmosphere (hydrogen gas volume fraction 2%) to prepare a monolithic hydrogen combustion catalyst.

[0092] Comparative Example 3

[0093] The comparative example of the present invention provides a method for preparing an integral hydrogen combustion catalyst, and the specific steps and parameters are as follows:

[0094] At room temperature, 0.2 g of an aqueous solution of platinum acetate containing 0.02 g / g of palladium was weighed and used to impregnate an equal volume of 1 g of a commercial Al2O3 carrier at room temperature; the carrier was calcined at 400°C for 2 hours in an air atmosphere, and finally reduced at 450°C for 4 hours in a hydrogen-nitrogen mixed gas atmosphere (hydrogen gas volume fraction 2%) to obtain a powdered hydrogen combustion catalyst.

[0095] Comparative Example 4

[0096] The comparative example of the present invention provides a method for preparing an integral hydrogen combustion catalyst, and the specific steps and parameters are as follows:

[0097] At room temperature, 1 g of iron foam (100 PPI) was ultrasonically treated in a dilute hydrochloric acid solution for 5 min to remove the surface nickel oxide layer, then washed with distilled water and dried;

[0098] At room temperature, 2.33 grams of nickel nitrate hexahydrate, 2.4 grams of urea, and 0.592 grams of ammonium fluoride were dissolved in 50 milliliters of distilled water. After stirring and dissolving completely, the solution was transferred to an autoclave. 1 gram of cleaned foamed iron was weighed and placed in the solution. The solution was kept at 120°C for 24 hours, cooled, removed, washed with distilled water, and dried to obtain a supported metal skeleton with a nanosheet morphology on the surface.

[0099] 0.22 g of a palladium acetate aqueous solution containing 0.02 g / g of palladium was weighed and diluted with water to 0.5 g. An equal volume of a metal skeleton with a nanosheet morphology on the surface of 1 g was impregnated at room temperature, calcined at 400°C for 2 hours in an air atmosphere, and finally reduced at 450°C for 4 hours in a hydrogen-nitrogen mixed gas atmosphere (hydrogen gas volume fraction 2%) to obtain an integral hydrogen combustion catalyst.

[0100] The Pt content of the catalyst can be measured by inductively coupled plasma atomic emission spectroscopy (ICP) characterization, and the mass content of the active component Pt is 0.5%.

[0101] Experimental Example 1

[0102] The specific surface area of ​​the monolithic hydrogen combustion catalyst prepared in each example and comparative example was tested using a gas adsorption method (BET method). The test results are shown in Table 1.

[0103] Experimental Example 2

[0104] The monolithic hydrogen combustion catalysts prepared in each embodiment and comparative example were subjected to hydrogen combustion activity test. The test method is as follows: the temperature was raised at 5°C / min in the range of 25-150°C, and the flow rate was 200 mL min -1 The activity of the monolithic hydrogen combustion catalyst to be tested was evaluated by a hydrogen-air (hydrogen content 2.5 vol%) mixture, with a catalyst loading of 0.5 g and a space velocity of 24000 mL g -1 h -1 The hydrogen conversion rate was calculated according to the formula: hydrogen conversion rate = (initial hydrogen content - tail gas hydrogen content) / initial hydrogen content × 100%. The measurement results are shown in Table 1.

[0105] Table 1

[0106] <![CDATA[Specific surface area (m 2 / g)]]> <![CDATA[T 50 (℃) a ]]> <![CDATA[T 100 (℃) b ]]> Example 1 77 65 85 Example 2 90 40 60 Example 3 81 50 75 Example 4 86 55 80 Example 5 95 30 50 Example 6 94 35 60 Comparative Example 1 2 100 145 Comparative Example 2 7 95 125 Comparative Example 3 15 105 150 Comparative Example 4 45 80 100

[0107] Note: T 50 (℃) a The temperature point at which the conversion rate is 50%; T 100 (℃) b The temperature at which the conversion rate is 100%.

[0108] As can be seen from Table 1, the specific surface areas of the integral hydrogen combustion catalysts prepared in Examples 1-6 are significantly higher than those in Comparative Examples 1-4, indicating that the method provided in Examples 1-6 of the present invention first grows a dispersed carrier with a high specific surface area on a metal skeleton by a hydrothermal method, and then impregnates the active component, so that the active component can be highly dispersed in the nanosheet dispersed carrier. However, the smaller specific surface areas in Comparative Examples 1 and 2 make it difficult to evenly disperse the active components. Therefore, the hydrogen catalytic combustion activity exhibited by Examples 1-6 is also significantly higher than that of Comparative Examples 1 and 2. By comparing Examples 1-6 and Comparative Example 3, it can be seen that the integral structural design of the hydrogen combustion catalyst can fully improve its mass transfer and heat transfer performance, which can promote the reaction performance. In particular, the integral hydrogen combustion catalyst prepared with a metal skeleton hydrothermally generated by nickel gallate as a carrier and platinum as an active component has a high mass transfer rate at 50°C and an air velocity of 24000 mL g -1 h -1By comparing Example 4 with Example 5, it can be seen that the metal skeleton carrier prepared in Example 5 has a larger specific surface area, which is more conducive to the dispersion of active components, and thus shows higher activity. Figure 5 It can be seen that after Example 5 was subjected to ultrasonic treatment for 100 hours (ultrasonic frequency 40 kHz, ultrasonic power 100 W), the mass loss of Example 5 was only 1%, showing a strong bonding strength between the catalyst and the carrier. The mass losses of other examples were close to that of Example 5 and are no longer shown one by one.

[0109] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A method for preparing a monolithic hydrogen combustion catalyst, characterized in that: The steps include: S1, placing the metal skeleton carrier in a citric acid solution or a gallic acid solution, and performing a hydrothermal reaction to obtain a supported metal skeleton carrier having a nanosheet morphology on the surface; The material of the metal skeleton carrier is any one of nickel, iron, cobalt, and copper; the temperature of the hydrothermal reaction is 80-200° C., and the time of the hydrothermal reaction is 1-48 hours; S2, impregnating the active component into the supported metal skeleton carrier prepared in step S1 to obtain a catalyst precursor; The active component includes at least one of platinum element or palladium element; S3, calcining and reducing the obtained catalyst precursor to obtain a monolithic hydrogen combustion catalyst; The mass percentage of the active component in the integral hydrogen combustion catalyst is 0.1-0.5%.

2. The method for preparing the monolithic hydrogen combustion catalyst according to claim 1, characterized in that: In step S1, the molar concentration of the citric acid solution is 0.001-1 mol / L; The molar concentration of the gallic acid solution is 0.001-1 mol / L.

3. The method for preparing the monolithic hydrogen combustion catalyst according to claim 1, wherein: In step S1, the ratio of the metal skeleton carrier to the citric acid solution is 0.001-1 g / mL; The usage ratio of the metal skeleton carrier to the gallic acid solution is 0.001-1 g / mL.

4. The method for preparing the integral hydrogen combustion catalyst according to any one of claims 1 to 3, characterized in that: In step S2, impregnation is performed using an equal volume impregnation method.

5. The method for preparing the integral hydrogen combustion catalyst according to any one of claims 1 to 3, characterized in that: In step S3, the calcination temperature is 200-600° C. and the calcination time is 0.5-24 h; And / or, the calcination is performed in an oxygen-containing atmosphere.

6. The method for preparing the integral hydrogen combustion catalyst according to any one of claims 1 to 3, characterized in that: The reduction temperature is 200-600°C and the reduction time is 0.5-24h; And / or, the reducing atmosphere is hydrogen or a hydrogen-nitrogen mixture.

7. The method for preparing the integral hydrogen combustion catalyst according to any one of claims 1 to 3, characterized in that: The morphological structure of the metal skeleton carrier is selected from any one of wire mesh, foam, fiber, round tube, and round disc; And / or, the metal skeleton carrier is pretreated by cleaning with an acidic solution.

8. The method for preparing the integral hydrogen combustion catalyst according to claim 7, characterized in that: The metal skeleton carrier is selected from one of foam nickel, foam copper, foam iron, fiber copper, wire mesh nickel, and wafer nickel.

9. An integral hydrogen combustion catalyst prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the integral hydrogen combustion catalyst according to claim 9 in hydrogen combustion, characterized in that: The hydrogen combustion reaction temperature is 25-150℃ and the space velocity is 1000-50000 mL g -1 h -1 .

Images