Molybdenum-based catalytic mesh, preparation method thereof and molybdenum-based silver mesh hydrogen peroxide catalytic bed

Abstract

The invention provides a molybdenum-based catalytic mesh, a preparation method of the molybdenum-based catalytic mesh and a molybdenum-based silver mesh hydrogen peroxide catalytic bed, and relates to the technical field of aerospace propulsion system engines. The preparation method of the molybdenum-based catalytic mesh is used for catalytic decomposition of hydrogen peroxide, and comprises the following steps: providing a pure molybdenum mesh made of molybdenum-based silk threads, and cleaning the pure molybdenum mesh to obtain a cleaned mesh; performing first surface treatment on the cleaned mesh to form a metal transition layer on the surface of the cleaned mesh to obtain an intermediate; and performing second surface treatment on the intermediate to form a metal catalyst layer on the surface of the metal transition layer to obtain the molybdenum-based catalytic mesh. The molybdenum-based catalytic mesh provided by the invention is applied to a mesh-based catalytic bed, so that the mesh-based catalytic bed can keep high catalytic efficiency and long service life, and also has high-temperature oxidation resistance and high economical efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of aerospace propulsion system engines, and particularly to a molybdenum-based catalytic mesh and a preparation method thereof, and a molybdenum-based silver mesh hydrogen peroxide catalytic bed. Background Art

[0002] As a non-toxic and pollution-free clean oxidant, hydrogen peroxide has become an important choice for oxygen supply and propellants in the life support system of aerospace equipment due to its catalytic decomposition characteristics, high density specific impulse, and ambient temperature storage advantages. The catalytic decomposition products of hydrogen peroxide are only oxygen and water vapor, and high-temperature oxygen-rich gas can be rapidly generated in combination with a catalytic bed. Therefore, it has key application value in the catalytic ignition of monopropellant / dipropellant engines and solid-liquid rocket engines.

[0003] At present, the catalytic bed decomposition technology of hydrogen peroxide can be divided into liquid catalysis, particulate catalysis, and mesh-based catalysis technologies. Liquid catalysis realizes decomposition by mixing and injecting liquid catalysts such as permanganate with hydrogen peroxide. Although the structure is simple, there are problems such as a decrease in specific impulse and excessive consumption caused by catalyst loss; particulate catalysis uses metal / metal oxide supported particulate catalysts, which are limited by the life attenuation caused by particulate erosion and wear, and the porosity is too high, seriously restricting the improvement of the bed load performance; mesh-based catalysis uses a catalytic mesh to catalyze the decomposition of hydrogen peroxide, which has more advantages in performance and life compared with liquid catalysis and particulate catalysis.

[0004] The catalytic mesh of the traditional mesh-based catalytic bed is composed of a metal substrate (such as nickel-based, palladium-based) and a catalyst layer attached to the surface of the substrate. Restricted by the material selection of the metal substrate and the bonding method between the metal substrate and the catalyst layer, it is generally difficult for the mesh-based catalytic bed to maintain high catalytic efficiency and long service life while taking into account high-temperature oxidation resistance and high economy, seriously restricting the performance and engineering practical value of hydrogen peroxide rocket engines.

[0005] In view of this, the present invention is specifically proposed. Summary of the Invention

[0006] The present application provides a molybdenum-based catalytic mesh and a preparation method thereof, and a molybdenum-based silver mesh hydrogen peroxide catalytic bed, aiming to solve the problem that it is difficult for the mesh-based catalytic bed in the prior art to maintain high catalytic efficiency and long service life while taking into account high-temperature oxidation resistance and high economy.

[0007] The first aspect of the present application provides a preparation method of a molybdenum-based catalytic mesh, and the molybdenum-based catalytic mesh is used for catalytic decomposition of hydrogen peroxide, including: providing a pure molybdenum mesh made of molybdenum-based silk threads, performing a cleaning treatment on the pure molybdenum mesh to obtain a cleaned mesh; performing a first surface treatment on the cleaned mesh to form a metal transition layer on the surface of the cleaned mesh to obtain an intermediate; performing a second surface treatment on the intermediate to form a metal catalytic layer on the surface of the metal transition layer to obtain a molybdenum-based catalytic mesh.

[0008] The preparation method of the molybdenum-based catalytic mesh provided by this application uses molybdenum-based wire as the substrate of the catalytic mesh. By cleaning the pure molybdenum mesh, the oxide layer and impurities on the surface of the pure molybdenum mesh can be removed, enabling the subsequent metal transition layer to be more stably bonded to the surface of the cleaned mesh. After the cleaned mesh undergoes the first surface treatment, the intermediate obtained has a metal transition layer on its surface. The metal transition layer can inhibit the oxidation of molybdenum to avoid material failure during the decomposition of hydrogen peroxide, and at the same time can improve the bonding force of the subsequent metal catalytic layer on the surface of the molybdenum-based catalytic mesh. By performing the second surface treatment on the intermediate, the metal catalytic layer can be tightly bonded to the surface of the metal transition layer to promote the catalytic decomposition of hydrogen peroxide as a catalyst layer.

[0009] Thus, in the prepared molybdenum-based catalytic mesh, the catalytic wire is successively, from the inside to the outside along the radial cross-section, the mesh substrate composed of molybdenum-based wire, the metal transition layer, and the metal catalytic layer. This application uses metallic molybdenum as the mesh substrate of the molybdenum-based catalytic mesh. Compared with using metallic nickel and metallic palladium as substrates, it can meet the mechanical property requirements during the catalytic decomposition of hydrogen peroxide with a concentration above 98% in a high-temperature environment. It has extremely excellent high-temperature resistance and mechanical properties, and at the same time has the advantages of a relatively low specific heat capacity, a low linear expansion coefficient, a high thermal conductivity, and a low price. The molybdenum-based catalytic mesh applied to the mesh-based catalytic bed can enable the mesh-based catalytic bed to maintain high catalytic efficiency and a long service life while taking into account high-temperature oxidation resistance and high economy, which is conducive to improving key parameters such as the ignition response time, service life, and combustion efficiency of the current hydrogen peroxide power system and reducing certain costs, thereby effectively improving the performance and engineering practical value of the hydrogen peroxide rocket engine.

[0010] In some embodiments, the first surface treatment includes: placing the cleaned mesh into a first electroplating solution for a first pre-plating treatment to form a pre-plated metal layer on the surface of the cleaned mesh, obtaining a pre-plated mesh; placing the pre-plated mesh into a second electroplating solution for a first electroplating treatment to form a metal coating on the surface of the pre-plated metal layer, obtaining an intermediate with a metal transition layer composed of the pre-plated metal layer and the metal coating.

[0011] In some embodiments, the first surface treatment further includes: soaking and activating the cleaned mesh in an acid solution before performing the first pre-plating treatment on the cleaned mesh.

[0012] In some embodiments, the second surface treatment includes: placing the intermediate into a third electroplating solution for a second pre-plating treatment to form a pre-plated metal active layer on the surface of the metal transition layer, obtaining a pre-plated intermediate; placing the pre-plated intermediate into a fourth electroplating solution for a second electroplating treatment to form a metal active layer on the surface of the pre-plated metal catalytic layer, obtaining a molybdenum-based catalytic mesh with a metal catalytic layer composed of the pre-plated metal active layer and the metal active layer.

[0013] In some embodiments, the second surface treatment further includes: immersing a molybdenum-based catalytic mesh with a metal catalytic layer in an oxidant solution for activation treatment; optionally, the oxidant solution is selected from any one of a hydrogen peroxide solution, a nitrate solution, or a nitric acid solution.

[0014] In some embodiments, the pure molybdenum mesh is woven in a plain weave with a number of molybdenum-based wires; and / or the mass percentage purity of metallic molybdenum in the molybdenum-based wires is greater than 99.9%; and / or the metal transition layer is a nickel layer and the metal catalytic layer is a silver layer; and / or the wire diameter of the molybdenum-based wires is 0.1 mm to 0.5 mm; the thickness of the metal transition layer is 10 to 20 μm; the thickness of the metal catalytic layer is 10 to 20 μm.

[0015] In some embodiments, the preparation method of the molybdenum-based catalytic mesh satisfies at least one of the following conditions: A. The components of the first electroplating solution and the second electroplating solution include nickel sulfate, nickel chloride, and boric acid; optionally, in the first electroplating solution and the second electroplating solution, the concentration of nickel sulfate is 200 to 300 g / L, the concentration of nickel chloride is 20 to 50 g / L, and the concentration of boric acid is 30 to 50 g / L; B. The pH value of the first electroplating solution and the second electroplating solution is 3.5 to 5.5; C. The components of the third electroplating solution and the fourth electroplating solution include silver nitrate, potassium cyanide, and acetic acid; optionally, in the third electroplating solution and the fourth electroplating solution, the concentration of silver nitrate is 1 to 3 g / L, the concentration of potassium cyanide is 100 to 150 g / L, and the concentration of acetic acid is 30 to 50 g / L; D. The pH value of the third electroplating solution and the fourth electroplating solution is 3.5 to 5.5.

[0016] In some embodiments, the preparation method of the molybdenum-based catalytic mesh satisfies at least one of the following conditions: E. In the first pre-plating treatment, the electroplating current is 20 to 100 A / cm 2 , the voltage is 10 to 20 V, the temperature is 20 to 30 °C, and the time is 2 to 3 min; F. In the first electroplating treatment, the electroplating current is 10 to 50 A / cm 2 , the voltage is 10 to 20 V, the temperature is 30 to 60 °C, and the time is 5 to 10 min; G. In the second pre-plating treatment, the electroplating current is 1 to 10 A / cm 2 , the voltage is 10 to 20 V, the temperature is 10 to 20 °C, and the time is 1 to 5 min; H. In the second electroplating treatment, the electroplating current is 1 to 5 A / cm 2 , the voltage is 10 to 20 V, the temperature is 20 to 30 °C, and the time is 1 to 10 min.

[0017] The second aspect of the present application provides a molybdenum-based catalytic mesh, which is made by the preparation method as described above. The catalytic wires in the molybdenum-based catalytic mesh sequentially include molybdenum-based wires, a metal transition layer, and a metal catalytic layer along the radial direction outward.

[0018] The third aspect of the present application provides a molybdenum-based silver mesh hydrogen peroxide catalytic bed, comprising: a plurality of molybdenum-based catalytic mesh sheets as described above; and a housing, wherein the plurality of molybdenum-based catalytic mesh sheets are stacked and pressed in the housing, and the catalytic filaments on two adjacent molybdenum-based catalytic mesh sheets are arranged at an angle. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without creative efforts.

[0020] Figure 1 It is a step block diagram of a method for preparing a molybdenum-based catalytic mesh sheet according to an embodiment of the present invention;

[0021] Figure 2 It is a schematic structural diagram of a catalytic filament in a molybdenum-based catalytic mesh sheet according to an embodiment of the present invention;

[0022] Figure 3 It is a schematic cross-sectional view along the radial direction of a catalytic filament in a molybdenum-based catalytic mesh sheet according to an embodiment of the present invention;

[0023] Figure 4 It is a schematic partial structural diagram of a molybdenum-based catalytic mesh sheet according to an embodiment of the present invention.

[0024] The reference numerals are as follows:

[0025] 100, catalytic filament; 10, molybdenum-based filament; 20, metal transition layer; 30, metal catalytic layer.

[0026] 1000, molybdenum-based catalytic mesh sheet. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] In the description of the present invention, it should be understood that if terms such as "center", "inner", "outer", "axial", "radial", "circumferential", etc. are used to indicate the orientation or positional relationship, without special explanation, it is understood as the orientation or positional relationship based on the drawings shown, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0028] In addition, for features limited with "first" and "second" for descriptive purposes only, they shall not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Features limited with "first" and "second" may explicitly or implicitly include at least one of the limited features. When the description of "a plurality" appears, generally it means at least two, such as two, three, etc., unless otherwise specifically and clearly defined.

[0029] As described above, aiming at the problem that the traditional network-based catalytic bed is difficult to maintain high catalytic efficiency and long service life while taking into account high temperature oxidation resistance and high economy, the general inventive concept of the embodiments of the present application provides a preparation method of a molybdenum-based catalytic mesh 1000. The molybdenum-based wire 10 with relatively high high temperature oxidation resistance and low cost is used as the metal substrate of the molybdenum-based catalytic mesh 1000, and a metal transition layer 20 is formed on the surface of the molybdenum-based wire 10. The metal transition layer 20 can avoid the oxidation reaction of the molybdenum-based wire 10 as a protective layer. Based on the surface of the metal transition layer 20, a metal catalytic layer 30 is further formed, which can improve the bonding force of the metal catalytic layer 30 to ensure that the molybdenum-based catalytic mesh 1000 has higher catalytic efficiency and longer service life under the high temperature working conditions of hydrogen peroxide catalytic decomposition.

[0030] Based on the above concept, referring to Figure 1 As shown, the embodiments of the present application provide a preparation method of a molybdenum-based catalytic mesh 1000, and the molybdenum-based catalytic mesh 1000 is used for hydrogen peroxide catalytic decomposition, including:

[0031] S100. Provide a pure molybdenum mesh made of molybdenum-based wire 10, and perform a cleaning treatment on the pure molybdenum mesh to obtain a cleaned mesh;

[0032] S200. Perform a first surface treatment on the cleaned mesh to form a metal transition layer 20 on the surface of the cleaned mesh to obtain an intermediate;

[0033] S300. Perform a second surface treatment on the intermediate to form a metal catalytic layer 30 on the surface of the metal transition layer 20 to obtain the molybdenum-based catalytic mesh 1000.

[0034] It should be noted that in the traditional technology, nickel-based or palladium-based wires are used as the metal substrates of the catalytic mesh. Although the nickel-based material has low cost, its heat resistance is poor, the melting point is only 1453 °C, and the linear expansion coefficient is large, and it is easy to deform after long-term use; while the palladium-based material has a high melting point, but the price is extremely expensive. Step S100 uses the molybdenum-based wire 10 as the substrate of the molybdenum-based catalytic mesh 1000. Compared with nickel-based or palladium-based wires, the molybdenum-based wire 10 has a high melting point of up to 2610 °C, and can have the advantages of good high temperature resistance, low specific heat capacity, low linear expansion coefficient, high thermal conductivity, good mechanical properties, and low price.

[0035] It should be understood that although the molybdenum-based wire 10 has high heat resistance, an oxide film will be formed on its surface in a high-temperature oxygen environment, and a strong oxidation-reduction reaction will occur, generating MoO3 or MoO2. The melting point and boiling point of MoO3 are relatively low and it will evaporate rapidly, resulting in material failure. Especially during the catalytic decomposition of hydrogen peroxide, the catalytic decomposition of hydrogen peroxide will generate high-temperature oxygen and water vapor, which will rapidly oxidize and decompose metallic molybdenum. Therefore, traditional hydrogen peroxide mesh-based catalytic beds often do not use molybdenum as the metal substrate. Moreover, the bonding performance between metallic molybdenum and metal catalyst layers 30 such as silver, platinum, and ruthenium is poor. When directly forming the metal catalyst layer 30 on the surface of the molybdenum-based wire 10, the bonding force between the metal catalyst layer 30 and the surface of the molybdenum-based wire 10 is weak, and the metal catalyst layer 30 is prone to peeling off. Also, due to the easy oxidation on the surface of the molybdenum-based wire 10, the bonding force of the metal catalyst layer 30 is not strong.

[0036] Therefore, in step S100, by cleaning the pure molybdenum mesh, the oxide layer and impurities such as oil stains on the surface of the molybdenum-based wire 10 in the pure molybdenum mesh can be removed, and the surface of the cleaned mesh is clean. By performing the first surface treatment on the cleaned mesh in step S200, a metal transition layer 20 is formed on the surface of the cleaned mesh. The metal transition layer 20 can prevent the molybdenum-based wire 10 from being oxidized, so as to avoid material failure during the high-temperature decomposition of hydrogen peroxide. Moreover, after the metal transition layer 20 is formed on the surface of the cleaned mesh, the intermediate obtained undergoes a second surface treatment in step S300, and the metal catalyst layer 30 formed on the surface of the metal transition layer 20 can be tightly bonded to the surface of the molybdenum-based catalytic mesh 1000, so as to overcome the problem that the metal catalyst layer 30 is prone to peeling off when directly bonded to the molybdenum-based wire 10. Furthermore, a molybdenum-based catalytic mesh 1000 with high physical and chemical properties is obtained. The molybdenum-based catalytic mesh 1000 is applied to the mesh-based catalytic bed, which can enable the mesh-based catalytic bed to maintain high catalytic efficiency and long service life while taking into account high-temperature oxidation resistance and high economy.

[0037] In some embodiments, the first surface treatment includes:

[0038] S210. Place the cleaned mesh into a first electroplating solution for a first pre-plating treatment to form a pre-plated metal layer on the surface of the cleaned mesh and obtain a pre-plated mesh;

[0039] S220. Place the pre-plated mesh into a second electroplating solution for a first electroplating treatment to form a metal coating on the surface of the pre-plated metal layer and obtain an intermediate with a metal transition layer 20 composed of the pre-plated metal layer and the metal coating.

[0040] To improve the electroplating adhesion between the metal coating and the surface of the mesh after cleaning, in step S210, by placing the cleaned mesh into the first electroplating solution for the first pre-plating treatment, a pre-plated metal layer can be formed on the surface of the cleaned mesh before the first electroplating treatment, obtaining a pre-plated mesh. The pre-plated metal layer on the surface of the pre-plated mesh can improve the surface smoothness of the adhesion surface of the metal coating formed by the subsequent first electroplating treatment, thereby improving the coating adhesion of the subsequent metal transition layer 20 on the surface of the molybdenum-based wire 10, providing good conditions for the first electroplating treatment; by placing the pre-plated mesh into the second electroplating solution in step S220 for the first electroplating treatment to form a metal coating, the metal coating can be tightly combined with the pre-plated mesh based on the smooth surface of the pre-plated metal layer, so that the pre-plated metal layer and the metal coating together constitute the metal transition layer 20, obtaining an intermediate product.

[0041] In some embodiments, the first surface treatment further includes: immersing and activating the cleaned mesh in an acid solution before the first pre-plating treatment of the cleaned mesh. By immersing and activating the cleaned mesh in an acid solution before the first pre-plating treatment, the surface activity of the cleaned mesh can be improved, so as to promote the pre-plated metal layer formed by the first pre-plating treatment to be tightly plated and combined on the surface of the cleaned mesh.

[0042] It should be noted that in the embodiments of the present application, the pre-plated metal layer and the metal coating can be made of the same metal material as the metal used for the non-metallic molybdenum and the non-metallic catalytic layer 30, so as to facilitate the formation of a homogeneous and uniform metal transition layer 20, thereby reducing the layered structure of the catalytic wire 100 in the molybdenum-based catalytic mesh 1000 and avoiding the loss of high-temperature resistance of the molybdenum-based catalytic mesh 1000 caused by the material interface. For example, the pre-plated metal layer and the metal coating can both be metal nickel layers. Nickel has good high-temperature resistance and excellent electroplating performance, and has good electroplating adhesion with the molybdenum-based wire 10 and the metal catalytic layer 30 as the metal transition layer 20, so that the structural stability of the molybdenum-based catalytic mesh 1000 is significantly improved.

[0043] In some embodiments, the second surface treatment includes:

[0044] S310. Placing the intermediate product into a third electroplating solution for the second pre-plating treatment to form a pre-plated metal active layer on the surface of the metal transition layer 20, obtaining a pre-plated intermediate product;

[0045] S320. Placing the pre-plated intermediate product into a fourth electroplating solution for the second electroplating treatment to form a metal active layer on the surface of the pre-plated metal catalytic layer 30, obtaining a molybdenum-based catalytic mesh 1000 with a metal catalytic layer 30 composed of a pre-plated metal active layer and a metal active layer.

[0046] The purpose of the second surface treatment is mainly to form the metal catalytic layer 30. In step S310, the intermediate is placed in the third electroplating solution for the second pre-plating treatment to form a pre-plated metal active layer on the surface of the metal transition layer 20, obtaining a pre-plated intermediate with a pre-plated metal active layer. The pre-plated metal active layer can improve the electroplating bonding force between the surface of the metal transition layer 20 and the subsequent metal active layer, increase the smoothness of the surface of the metal transition layer 20, and provide good conditions for the subsequent second electroplating treatment; in step S320, the pre-plated intermediate is placed in the fourth electroplating solution for the second electroplating treatment, and the formed metal active layer can be tightly bonded to the surface of the pre-plated metal active layer, thereby obtaining the molybdenum-based catalytic mesh 1000 with a metal catalytic layer 30 composed of the pre-plated metal active layer and the metal active layer together.

[0047] It should be noted that in the embodiments of the present application, the pre-plated metal active layer and the metal active layer can be the same metal catalytic material capable of catalytic reaction with hydrogen peroxide, so as to facilitate the formation of a homogeneous and uniform metal catalytic layer 30 and avoid the loss of high-temperature resistance performance of the molybdenum-based catalytic mesh 1000 caused by the material interface. For example, the pre-plated metal active layer and the metal active layer can both be metal silver layers. Silver has excellent catalytic activity and can promote the catalytic decomposition of hydrogen peroxide, so as to facilitate the improvement of the catalytic efficiency of the molybdenum-based catalytic mesh 1000.

[0048] In some embodiments, the cleaning treatment includes degreasing and decontaminating the pure molybdenum mesh with a high-temperature alkaline solution, and after the degreasing and decontaminating treatment, the obtained material is rinsed with multiple channels of clean water, then infiltrated in a low-concentration aqueous hydrogen peroxide solution, and finally rinsed with clean water multiple times to absorb the residual cleaning solution, so as to remove the oil stains on the surface of the molybdenum-based filaments 10 of the pure molybdenum mesh and obtain a pure active surface. Among them, the high-temperature alkaline solution can be selected from at least one of sodium hydroxide solution, potassium hydroxide solution, sodium carbonate solution, and potassium carbonate solution.

[0049] In some embodiments, the pure molybdenum mesh is woven in a plain weave with a number of molybdenum-based filaments. Specifically, a number of molybdenum-based filaments are used as warp and weft respectively, and the warp (longitudinal) and weft (transverse) are alternately interwoven in an over-under manner, preferably in a 90° perpendicular staggered and alternating weave. The obtained molybdenum-based catalytic mesh 1000 refers to Figure 4 As shown, the pure molybdenum mesh is woven in a plain weave with a number of molybdenum-based filaments, so that the molybdenum-based catalytic mesh 1000 can obtain better wettability, lower pressure drop and higher contact area, and at the same time has better mechanical properties and impact resistance.

[0050] In some embodiments, the second surface treatment further includes: immersing the molybdenum-based catalytic mesh 1000 with a metal catalytic layer into an oxidant solution for activation treatment; by immersing the molybdenum-based catalytic mesh 1000 with a metal catalytic layer into an oxidant solution for activation treatment, the activation treatment has a crucial impact on the initial reaction rate of the catalyst (i.e., the metal catalytic layer 30). First, it can regulate the microscopic structural characteristics of the surface of the metal catalytic layer 30, making the surface morphology of the metal catalytic layer 30 change from a smooth and flat interface to an irregular structure, greatly increasing the number of unsaturated defect sites, increasing the catalytic active sites, and significantly increasing the specific surface area of the metal catalytic layer 30. Second, it changes the elemental valence state on the surface of the metal catalytic layer 30, improving the catalytic activity.

[0051] In some embodiments, the oxidant solution used for the activation treatment is selected from any one of hydrogen peroxide solution, nitrate solution, or nitric acid solution. For example, the oxidant solution can be selected from any one of 50% concentration of H2O2, 90% concentration of H2O2, 95% concentration of H2O2, 98% concentration of H2O2, samarium nitrate solution, or nitric acid solution. In some embodiments, the mass percentage of metallic molybdenum in the molybdenum-based wire 10 is greater than 99.9%, the metal transition layer 20 is a nickel layer, and the metal catalytic layer 30 is a silver layer; the purity of molybdenum in the molybdenum-based wire 10 is greater than 99.9%, that is, the molybdenum-based wire 10 in the embodiments of the present application uses pure molybdenum. Since the electroplating performance of pure molybdenum is poor, the silver layer electroplated directly on the surface of pure molybdenum has a weak bonding force with molybdenum, and the coating is easy to peel off. Therefore, a nickel layer is used as the metal transition layer 20, and there is a high electroplating bonding force between metallic nickel, pure molybdenum, and silver, so that the molybdenum-based catalytic wire mesh 1000 has high structural stability and meets the application requirements of the high-temperature catalytic decomposition environment of hydrogen peroxide.

[0052] In some embodiments, the wire diameter of the molybdenum-based wire 10 is 0.1 mm to 0.5 mm. For example, the wire diameter of the molybdenum-based wire 10 can be 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, or any wire diameter value within the range of 0.1 mm to 0.5 mm.

[0053] In some embodiments, the thickness of the metal transition layer 20 is 10 to 20 μm. For example, the thickness of the metal transition layer 20 can be 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, or any thickness value within the range of 10 to 20 μm.

[0054] In some embodiments, the thickness of the metal catalytic layer 30 is 10 - 20 μm. For example, the thickness of the metal catalytic layer 30 can be 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, or any thickness value within the range of 10 - 20 μm.

[0055] When the metal transition layer 20 is a nickel layer, in some embodiments, the components of the first electroplating solution and the second electroplating solution include nickel sulfate, nickel chloride, and boric acid. Nickel sulfate, as the main metal ion source for the first pre - plating treatment and the first electroplating treatment, can provide the metal ion source required for the metal transition layer 20 during the electroplating process. The nickel chloride solution is mainly used to provide chloride ions to prevent the passivation of the nickel anode, promote the normal dissolution of the anode, and the nickel chloride solution can also be used as a secondary metal ion source for the first pre - plating treatment and the first electroplating treatment to supplement some nickel ions. Boric acid, as the pH buffer for the first electroplating solution and the second electroplating solution, is used to adjust the pH value of the solution, prevent the occurrence of hydrogen evolution reaction, and can improve the toughness of the metal transition layer 20, that is, refine the grains through adsorption, reduce the brittleness of the metal transition layer 20, so as to ensure the coating quality of the metal transition layer 20.

[0056] Furthermore, in the first electroplating solution and the second electroplating solution, the concentration of nickel sulfate is 200 - 300 g / L, the concentration of nickel chloride is 20 - 50 g / L, and the concentration of boric acid is 30 - 50 g / L. Nickel sulfate, as the main salt for nickel plating, its concentration determines the conductivity of the electroplating solution, the nickel plating speed, and the maximum allowable current density. When the concentration of nickel sulfate is 200 - 300 g / L, it is beneficial to improve the electroplating speed, expand the current density, make the coating delicate, and improve the nickel dispersion ability, so as to effectively balance the electroplating efficiency and the coating quality. When the concentration of nickel chloride is 20 - 50 g / L, it is more conducive to activating the anode and preventing anode passivation while avoiding excessive stress during electroplating. Insufficient boric acid will cause fluctuations in the pH of the electroplating solution, and the metal transition layer 20 is prone to pinholes, blackening, and burning. Excessive boric acid will lead to too high viscosity of the electroplating solution, affecting the electroplating efficiency. Therefore, controlling the boric acid concentration within the range of 30 - 50 g / L is more conducive to effectively balancing the electroplating efficiency and the coating quality.

[0057] Furthermore, the pH value of the first electroplating solution and the second electroplating solution is 3.5 - 5.5. When the pH value of the first electroplating solution and the second electroplating solution is within this range, the first electroplating solution and the second electroplating solution are in an acidic environment, which is conducive to the stable deposition of nickel ions and avoids the hydrolysis of nickel ions to form nickel hydroxide precipitation.

[0058] When the metal catalyst layer 30 is a silver layer, in some embodiments, the components of the third electroplating solution and the fourth electroplating solution include silver nitrate, potassium cyanide, and acetic acid; silver nitrate can provide silver ions, which are reduced to metallic silver and deposited on the surface of the metal transition layer 20 during electrolysis; potassium cyanide can form a stable complex with silver ions (such as Ag(CN)2 - ), delay the reduction rate of silver, increase the cathodic polarization, make the metal catalyst layer 30 more uniform and dense, and can also promote anodic dissolution, maintain the stability of the silver ion concentration in the plating solution, and enhance the conductivity of the electroplating solution;; acetic acid, as a buffer, can stabilize the pH of the third electroplating solution and the fourth electroplating solution, prevent the decomposition of cyanide, improve the conductivity of the plating solution, promote anodic dissolution, inhibit side reactions, and reduce the pinholes in the metal catalyst layer 30.

[0059] Furthermore, in the third electroplating solution and the fourth electroplating solution, the concentration of silver nitrate is 1 - 3 g / L, the concentration of potassium cyanide is 100 - 150 g / L, and the concentration of acetic acid is 30 - 50 g / L. Within the range of 1 - 3 g / L of silver nitrate concentration, it is beneficial to increase the deposition rate, shorten the electroplating time, and make the coating more delicate and uniform, avoiding the negative impacts such as coarse crystal grains, rough surface of the coating caused by too high silver nitrate concentration, and slow deposition rate, low production efficiency, and increased energy consumption caused by too low silver nitrate concentration; within the range of 100 - 150 g / L of potassium cyanide concentration, the complex stability of silver ions can be enhanced, the metal catalyst layer 30 can be made smoother, and it is beneficial to improve the anodic dissolution efficiency and reduce the risk of anode passivation, so as to take into account the quality of the metal catalyst layer 30 while improving the electroplating efficiency; insufficient acetic acid will cause fluctuations in the pH of the plating solution, and the metal catalyst layer 30 is prone to pinholes, blackening and burning phenomena, while excessive acetic acid will lead to too high viscosity of the plating solution, affecting the electroplating efficiency, and may also corrode the equipment or substrate. Therefore, controlling the acetic acid concentration within the range of 30 - 50 g / L is more conducive to effectively taking into account the electroplating efficiency and the coating quality. Further, the pH value of the third electroplating solution and the fourth electroplating solution is 3.5 - 5.5. The third electroplating solution and the fourth electroplating solution are in an acidic environment, which is beneficial to the stable deposition of silver ions and avoids the reaction of silver ions with hydroxide ions to form silver oxide precipitation.

[0060] In some embodiments, in the first pre - plating treatment, the electroplating current is 20 - 100 A / cm 2 , the voltage is 10 - 20 V, the temperature is 20 - 30 °C, and the time is 2 - 3 min; in the first electroplating treatment, the electroplating current is 10 - 50 A / cm 2, the voltage is 10 - 20V, the temperature is 30 - 60°C, and the time is 5 - 10 min; the electroplating current in the first pre - plating treatment is higher than that in the first electroplating treatment. The electroplating temperature is moderate and the electroplating time is short. The higher current density can accelerate the deposition rate of nickel ions and quickly form a dense pre - plated metal layer. The moderate temperature is conducive to the stability of the plating solution and ion migration. The electroplating time of 2 - 3 min is sufficient to form a thin and dense pre - plated metal layer; the electroplating current in the first electroplating treatment can ensure the uniform deposition of nickel, avoid roughness or stress in the metal coating, and the higher temperature is beneficial to improving the conductivity of the plating solution and the ion migration rate, improving the quality of the metal coating. The longer electroplating time can ensure that the metal transition layer 20 reaches the required thickness and better surface quality.

[0061] In some embodiments, in the second pre - plating treatment, the electroplating current is 1 - 10 A / cm 2 , the voltage is 10 - 20V, the temperature is 10 - 20°C, and the time is 1 - 5 min; in the second electroplating treatment, the electroplating current is 1 - 5 A / cm 2 , the voltage is 10 - 20V, the temperature is 20 - 30°C, and the time is 1 - 10 min; the electroplating current in the second pre - plating treatment is higher than that in the second electroplating treatment. In the second pre - plating treatment, the higher current density is beneficial to accelerating the deposition of silver ions and quickly forming a uniform pre - plated metal active layer. The short time of 1 - 5 min is sufficient to form a thin and uniform pre - plated metal active layer. In the second electroplating treatment, the lower current density and higher ambient temperature can ensure the uniform deposition of the silver layer, avoid roughness or pinholes in the coating, improve the coating quality, and the longer electroplating time can ensure that the metal catalytic layer 30 reaches the required thickness and better surface quality.

[0062] In the embodiments of the present application, both the second pre - plating treatment and the second electroplating treatment use a pure silver plate (purity greater than 99.9%) as the anode.

[0063] Reference Figure 2 、 Figure 3 and Figure 4 As shown, another embodiment of the present application provides a molybdenum - based catalytic mesh 1000, which can be made by the preparation method in the above - mentioned embodiments. The molybdenum - based catalytic mesh 1000 is made by plain weave. As shown in Figure 3 , the catalytic wire 100 in the molybdenum - based catalytic mesh 1000 sequentially includes a molybdenum - based wire 10, a metal transition layer 20, and a metal catalytic layer 30 along the radial direction outward.

[0064] In the embodiments of the present application, the catalytic wire 100 in the molybdenum - based catalytic mesh 1000 uses the molybdenum - based wire 10 as the mesh substrate, the metal transition layer 20 is preferably a nickel layer, and the metal catalytic layer 30 is preferably a silver layer.

[0065] Compared with nickel-based wires or palladium-based wires, the molybdenum-based material has a melting point as high as 2610 °C, a boiling point of 5560 °C, a linear expansion coefficient of 4×10 -6 / K, a tensile strength of 600 MPa, and a thermal conductivity of 142 W / m·K. Analyzing from the aspects of temperature resistance performance and lifespan: the adiabatic temperature of the adiabatic catalytic decomposition of 90% concentration hydrogen peroxide is 1025 K, and the adiabatic temperature of the catalytic decomposition of 98% concentration hydrogen peroxide is 1217 K. The mechanical properties of nickel-based at 1200 K are relatively low, and the elongation rate has exceeded 100%, so it cannot be used as the catalytic substrate of the 98% hydrogen peroxide catalytic bed. The yield strength and tensile strength of palladium-based and molybdenum-based at high temperatures are both relatively high, and the elongation rate is less than 50%, so they can be used as the substrates for the long-term operation of the 98% concentration hydrogen peroxide catalytic bed. However, the price of metallic palladium is far higher than that of molybdenum, and the economy is poor, which is not conducive to reducing the production cost.

[0066] Another embodiment of the present application provides a molybdenum-based silver mesh hydrogen peroxide catalytic bed. The molybdenum-based silver mesh hydrogen peroxide catalytic bed, as a mesh-based catalytic bed, includes: a plurality of molybdenum-based catalytic mesh sheets 1000 as described above, and the metal catalytic layer 30 of the molybdenum-based catalytic mesh sheet 1000 is a silver layer; and a housing, and a plurality of molybdenum-based catalytic mesh sheets 1000 are stacked and pressed in the housing, and the catalytic wires 100 on two adjacent molybdenum-based catalytic mesh sheets 1000 are arranged at an angle.

[0067] In the molybdenum-based silver mesh hydrogen peroxide catalytic bed provided by the embodiment of the present application, a plurality of molybdenum-based catalytic mesh sheets 1000 are stacked and pressed in the housing, that is, multiple molybdenum-based catalytic mesh sheets 1000 are loaded into the housing, and pressure is applied at both ends to press them tightly to ensure the compactness of the mesh-based catalytic bed. The purpose of pressing tightly can not only reduce the gap between the catalytic bed layers, increase the contact surface area with hydrogen peroxide so as to increase the catalytic decomposition rate and reduce the axial length, but also increase the impact resistance of the catalytic bed. The principle of pressing and assembling is to make the catalytic wires between different layers of the mesh-based catalytic bed stagger as much as possible, aiming to stagger the flow channels, increase the turbulence degree, and enable the undecomposed hydrogen peroxide to fully contact the active components on the surface of the mesh sheet. Among them, the pressing force when a plurality of molybdenum-based catalytic mesh sheets 1000 are stacked and pressed can be 1 to 10 MPa, and the staggering angle during stacking can be 30° to 60°, preferably 45°.

[0068] To verify the advantages of the mesh-based catalytic bed (i.e., the molybdenum-based silver mesh hydrogen peroxide catalytic bed) of the embodiment of the present application, nickel-based catalytic mesh sheets and palladium-based catalytic mesh sheets are prepared by the same preparation method. Among them, the nickel-based catalytic mesh sheets use nickel-based wires as the mesh sheet substrate, and the palladium-based catalytic mesh sheets use palladium-based wires as the mesh sheet substrate, and the obtained nickel-based catalytic mesh sheets and palladium-based catalytic mesh sheets are respectively made into mesh-based catalytic beds by the same method. Hydrogen peroxide is respectively introduced into the mesh-based catalytic bed of the embodiment of the application, the mesh-based catalytic bed made of nickel-based catalytic mesh sheets, and the mesh-based catalytic bed made of palladium-based catalytic mesh sheets for experiments, and the obtained results are shown in Table 1 below:

[0069] Table 1. Statistical Table of the Performance of the Mesh-Based Catalytic Bed

[0070]

[0071] It should be noted that the above three mesh-based catalytic beds all use silver as the metal catalytic layer.

[0072] Combined with Table 1, through comparative analysis of the catalytic efficiency and bed load: the three mesh-based catalytic beds all use silver as the metal catalytic layer (catalyst), and silver is a metal with relatively high activity for catalyzing the decomposition of hydrogen peroxide. During the flow process, hydrogen peroxide only undergoes a surface catalytic reaction with the silver on the surface of the mesh. Therefore, the catalyst for catalytically decomposing hydrogen peroxide in all three cases is silver. And the catalytic efficiency under a certain bed load is only related to the catalytic activity of the catalyst. Therefore, the catalytic efficiencies of the three mesh-based catalytic beds under a certain bed load are roughly the same.

[0073] The traditional mesh-based catalytic bed made of nickel-based wires is only suitable for the catalytic decomposition of 80% - 90% hydrogen peroxide because the temperature of 98% hydrogen peroxide decomposition will significantly reduce the mechanical properties of the nickel-based catalytic mesh, and the service life of catalytically decomposing 90% hydrogen peroxide is also short. Molybdenum far exceeds nickel in physical property parameters and is slightly inferior to palladium-based materials, but molybdenum has a small linear expansion coefficient and can work at high temperatures for a long time without deformation. As the mesh substrate, it is suitable for the long-term catalytic decomposition of 80% - 98% hydrogen peroxide. Moreover, the mesh-based catalytic bed using molybdenum-based wires 10 has a small specific heat capacity and a large thermal conductivity. Therefore, among the three materials, the temperature rise rate of the catalytic mesh substrate used as the mesh-based catalytic bed is the fastest, and the delay time and response time of the catalytic bed also exceed those of the traditional nickel-based catalytic bed. The fastest measured delay time of the molybdenum-based catalytic bed can be less than 100 ms.

[0074] Therefore, the molybdenum-based silver mesh hydrogen peroxide catalytic bed provided by the embodiments of the present application can replace the expensive palladium mesh-based catalytic bed in terms of catalytic efficiency, applicable hydrogen peroxide concentration, bed load, service life, etc., but the cost is only 1 / 26.7 of the palladium mesh-based catalytic bed. The molybdenum-based silver mesh hydrogen peroxide catalytic bed provided by the embodiments of the present application exceeds the nickel mesh-based catalytic bed and the palladium mesh-based catalytic bed in terms of parameters such as startup delay time, deformation rate, temperature rise rate, and price.

[0075] The embodiments of the present application use metal molybdenum as the mesh substrate of the molybdenum-based catalytic mesh 1000. The formed molybdenum-based silver mesh hydrogen peroxide catalytic bed will not affect the engine performance compared with liquid catalysts, and has a higher bed load and catalytic efficiency and a longer service life compared with particle catalytic beds; compared with general nickel mesh-based catalytic beds and palladium mesh-based catalytic beds, the catalytic efficiency and bed load are the same, and it has more advantages in terms of startup delay time, deformation rate, temperature rise rate, price, etc.

[0076] In summary, while maintaining high catalytic efficiency and long service life, the molybdenum-based catalytic mesh 1000 provided by the embodiments of the present application takes into account high temperature oxidation resistance and high economy. When the molybdenum-based catalytic mesh 1000 is applied to a mesh-based catalytic bed to form a molybdenum-based silver mesh hydrogen peroxide catalytic bed, the mesh-based catalytic bed can have the advantages of excellent temperature resistance, high efficiency, fast response, low cost, long life, etc., so as to improve key parameters such as the ignition response time, life, and combustion efficiency of the current hydrogen peroxide power system and reduce certain costs, thereby improving the performance and engineering practical value of the hydrogen peroxide rocket engine.

[0077] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A preparation method of a molybdenum-based catalytic mesh, characterized in that, The molybdenum-based catalytic mesh is used for catalytic decomposition of hydrogen peroxide and includes: Providing a pure molybdenum mesh made of molybdenum-based wires, and cleaning the pure molybdenum mesh to obtain a cleaned mesh; Performing a first surface treatment on the cleaned mesh to form a metal transition layer on the surface of the cleaned mesh, obtaining an intermediate; Performing a second surface treatment on the intermediate to form a metal catalytic layer on the surface of the metal transition layer, obtaining a molybdenum-based catalytic mesh.

2. The preparation method of the molybdenum-based catalytic mesh according to claim 1, characterized in that, The first surface treatment includes: Placing the cleaned mesh into a first electroplating solution for a first pre-plating treatment to form a pre-plated metal layer on the surface of the cleaned mesh, obtaining a pre-plated mesh; Placing the pre-plated mesh into a second electroplating solution for a first electroplating treatment to form a metal coating on the surface of the pre-plated metal layer, obtaining an intermediate having the metal transition layer jointly composed of the pre-plated metal layer and the metal coating.

3. The preparation method of the molybdenum-based catalytic mesh according to claim 2, characterized in that, The first surface treatment further includes: soaking and activating the cleaned mesh in an acid solution before performing the first pre-plating treatment on the cleaned mesh.

4. The preparation method of the molybdenum-based catalytic mesh according to claim 2 or 3, characterized in that, The second surface treatment includes: Placing the intermediate into a third electroplating solution for a second pre-plating treatment to form a pre-plated metal active layer on the surface of the metal transition layer, obtaining a pre-plated intermediate; Placing the pre-plated intermediate into a fourth electroplating solution for a second electroplating treatment to form a metal active layer on the surface of the pre-plated metal catalytic layer, obtaining a molybdenum-based catalytic mesh having the metal catalytic layer jointly composed of the pre-plated metal active layer and the metal active layer.

5. The preparation method of the molybdenum-based catalytic mesh according to claim 4, wherein, The second surface treatment further includes: immersing the molybdenum-based catalytic mesh having the metal catalytic layer in an oxidant solution for activation treatment; Optionally, the oxidant solution is selected from any one of a hydrogen peroxide solution, a nitrate solution, or a nitric acid solution.

6. The method for preparing the molybdenum-based catalytic mesh according to claim 1, wherein the pure molybdenum mesh is woven in a plain weave with a plurality of the molybdenum-based wires; and / or the mass percentage of metallic molybdenum in the molybdenum-based wire is greater than 99.9%; and / or the metal transition layer is a nickel layer, and the metal catalytic layer is a silver layer; and / or the wire diameter of the molybdenum-based wire is 0.1 mm to 0.5 mm; the thickness of the metal transition layer is 10 to 20 μm; the thickness of the metal catalytic layer is 10 to 20 μm.

7. The preparation method of the molybdenum-based catalytic mesh according to claim 4, characterized in that, Meet at least one of the following conditions: A. The components of the first electroplating solution and the second electroplating solution include nickel sulfate, nickel chloride, and boric acid; optionally, in the first electroplating solution and the second electroplating solution, the nickel sulfate concentration is 200 to 300 g / L, the nickel chloride concentration is 20 to 50 g / L, and the boric acid concentration is 30 to 50 g / L; B. The pH value of the first electroplating solution and the second electroplating solution is 3.5 to 5.5; C. The components of the third electroplating solution and the fourth electroplating solution include silver nitrate, potassium cyanide, and acetic acid; optionally, in the third electroplating solution and the fourth electroplating solution, the silver nitrate concentration is 1 to 3 g / L, the potassium cyanide concentration is 100 to 150 g / L, and the acetic acid concentration is 30 to 50 g / L; D. The pH value of the third electroplating solution and the fourth electroplating solution is 3.5 to 5.

5.

8. The preparation method of the molybdenum-based catalytic mesh according to claim 4, characterized in that, Meet at least one of the following conditions: E. In the first pre-plating treatment, the electroplating current is 20 - 100 A / cm 2 , the voltage is 10 - 20 V, the temperature is 20 - 30 °C, and the time is 2 - 3 min; F. In the first electroplating treatment, the electroplating current is 10 - 50 A / cm 2 , the voltage is 10 - 20 V, the temperature is 30 - 60 °C, and the time is 5 - 10 min; G. In the second pre-plating treatment, the electroplating current is 1 - 10 A / cm 2 , the voltage is 10 - 20 V, the temperature is 10 - 20 °C, and the time is 1 - 5 min; H. In the second electroplating treatment, the electroplating current is 1 - 5 A / cm 2 , the voltage is 10 - 20 V, the temperature is 20 - 30 °C, and the time is 1 - 10 min.

9. A molybdenum-based catalytic mesh, characterized in that, Prepared by the preparation method described in any one of claims 1 to 8, and the catalytic filaments in the molybdenum-based catalytic mesh sheet sequentially include a molybdenum-based filament, a metal transition layer, and a metal catalytic layer along the radial direction outward.

10. A molybdenum-based silver mesh hydrogen peroxide catalytic bed, characterized in that, Comprising: A plurality of molybdenum-based catalytic mesh sheets as described in claim 9; And A housing, wherein a plurality of the molybdenum-based catalytic mesh sheets are laminated and pressed in the housing, and the catalytic filaments on two adjacent molybdenum-based catalytic mesh sheets are arranged at an angle.

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