Tubular porous metal film and method for manufacturing the same

Abstract

The present application relates to a kind of tubular porous metal film and its preparation method, with metal mesh as raw material, by sheet coiling machine, metal mesh is rolled into compact tubular structure, then using the mode of cathodic electrodeposition metal element between each mesh surface is anchored, obtain tubular precursor film;The precursor film is placed in inert or reducing atmosphere and sintered at high temperature, to obtain tubular porous metal film.The preparation method is simple, easy to operate, high yield, the metal film material provided by the present application has better flexibility and mechanical strength compared with traditional powder sintered metal film, while the film hole structure is regular and ordered, the film hole size distribution is uniform, fine and controllable.The film material can be used in wastewater treatment, dust filtration, membrane catalytic reactor, catalytic oxidation membrane base film and composite membrane support body and other fields, especially in extreme conditions also shows good application prospect.

Description

Technical Field

[0001] This invention belongs to the field of novel membrane material technology, specifically relating to a tubular porous metal membrane and its preparation method. Technical Background

[0002] With the continuous improvement of my country's industrialization and development level, environmental pollution problems are becoming increasingly severe, with frequent incidents of water and air pollution. In response to these environmental pollution issues, innovative technologies are urgently needed to effectively prevent and control pollution. Membrane separation technology is an emerging technology that uses separation membranes as its core, leveraging the selective permeability of membranes to achieve the separation, purification, and concentration of different components. Compared with traditional separation technologies, membrane separation technology has become one of the most promising separation technologies of the new century due to its advantages such as high separation efficiency, energy saving and environmental protection, small footprint, and ease of scale-up. It has been widely used in gas separation, water treatment, gas dust removal, membrane reactors, and other fields. Currently, commonly used membrane materials mainly include polymer membranes, ceramic membranes, carbon membranes, metal membranes, and various composite membranes.

[0003] Porous metal membranes are a novel type of membrane material that combines the separation selectivity of membrane materials with the excellent electrical conductivity, thermal stability, chemical stability, and mechanical strength of metal materials, as well as unique modifiability. Furthermore, they can be used in specific and extreme conditions such as high temperature and high pressure environments. Currently, commonly reported porous metal membranes are generally made from metal powder as raw material, formed through pressure molding or phase transformation molding, and then sintered at high temperature. The pore structure is composed of particle packing, resulting in an inhomogeneous pore structure, poor pore size uniformity, and a wide pore size distribution. At the same time, sintered powder typically exhibits poor flexibility. In cases of small size and thin thickness, the mechanical strength of the membrane material is limited, restricting the application of metal membranes. Summary of the Invention

[0004] The purpose of this invention is to provide a tubular porous metal membrane with high flexibility, high mechanical strength, and adjustable pore structure, as well as a method for preparing the same, thereby improving the shortcomings of traditional porous metal membrane materials such as poor flexibility, insufficient mechanical strength, and uneven pore size distribution.

[0005] The specific technical solution adopted in this invention is as follows:

[0006] On one hand, the present invention provides a tubular porous metal membrane, which is prepared by mechanical winding, electrodeposition anchoring and high-temperature sintering of metal mesh as raw material.

[0007] Preferably, the porous metal membrane has an outer diameter of 1–100 mm, an average pore size of 0.1–20.0 μm, and a porosity of 20%–60%.

[0008] On the other hand, the present invention provides a method for preparing the above-mentioned tubular porous metal film, comprising the following steps:

[0009] (1) Using metal mesh as raw material, the metal mesh is rolled into a tight tubular structure by a thin plate rolling machine, and then anchored by cathodic electrodeposition of metal elements to obtain a tubular precursor film.

[0010] (2) The tubular precursor film is placed in an inert or reducing atmosphere and sintered at high temperature to obtain a tubular porous metal film.

[0011] Preferably, the preparation process of the tubular precursor film in step (1) specifically includes: ① cutting the metal mesh into rectangles of a certain size, placing them in a thin plate rolling machine, setting the rolling machine parameters, and rolling them into a dense tubular structure; ② placing the rolled tubular multilayer metal mesh in the corresponding electrolyte, using the tubular multilayer metal mesh as the cathode, and platinum electrode, graphite electrode, or corresponding metal electrode as the anode, and anchoring the mesh surfaces of the metal mesh by electrodeposition of metal elements to obtain the precursor film.

[0012] As a further preferred embodiment, the metal mesh is one of commercially available stainless steel mesh, iron mesh, copper mesh, titanium mesh, tungsten mesh, molybdenum mesh, and silver mesh; the weaving method of the metal mesh is one of plain weave, twill weave, and reverse weave; the mesh count of the metal mesh is 20 to 1000 mesh, with a preferred mesh count of 200 to 600 mesh. The rolling conditions are as follows: the working pressure of the plate rolling machine is 0.5–20 MPa, and the rolling speed is 0.1–80 m / min, with a preferred rolling speed of 0.3–2 m / min; the inner diameter of the rolled tubular precursor film is 0.5–80 mm, and the wall thickness is 0.1–30 mm; the electrolyte is a solution containing one or more of the following: nitrates, sulfates, oxalates, carbonates, chlorides, and fluorides, corresponding to the metal element of the metal mesh, with a preferred concentration of 0.2–2 M; the deposition voltage is 0.4–20 V, and the deposition time is 1–600 min, with a preferred deposition time of 20–120 min.

[0013] Preferably, the sintering process of the precursor film in step (2) is as follows: the obtained tubular precursor film is placed in a specific protective gas atmosphere and subjected to high-temperature sintering treatment by a programmed temperature rise method to obtain a tubular porous metal film.

[0014] As a further preferred embodiment, the protective gas is one or a mixture of nitrogen, argon, helium, hydrogen, and carbon monoxide; the temperature program is as follows: heating rate of 0.01–50 °C / min, final sintering temperature of 800–1800 °C, isothermal time of 0.1–8.0 h, followed by natural cooling to room temperature after the program is completed, resulting in a tubular porous metal membrane. The metal membrane prepared by this invention has an ordered pore structure and uniform pore size distribution. Furthermore, the pore structure can be precisely controlled by adjusting the mesh size, number of layers, electrodeposition process, and sintering process of the raw material metal mesh. In particular, by using metal meshes of different mesh sizes spliced ​​together as raw materials, asymmetric porous metal membranes can be prepared.

[0015] The porous metal membrane described above in this invention can be used for wastewater treatment, dust filtration, membrane catalytic reactors, catalytic oxidation membrane base membranes, and composite membrane supports.

[0016] This invention provides a method for preparing a tubular porous metal membrane. The raw material for this metal membrane is a two-dimensional metal mesh material. Spatially, the plane formed by the X and Y axes is composed of interwoven metal wires, which inherently possesses high mechanical strength. Furthermore, between the layers, the connection between the metal mesh layers is anchored by electrodeposition of elemental metal, and high-temperature sintering further enhances the bonding force between the various metal mesh surfaces. This preparation method is simple, easy to operate, and has a high yield. Compared to traditional powder-sintered metal membrane materials (formed by sintering and bonding together macroscopically zero-dimensional metal powders), the metal membrane material provided by this invention exhibits superior flexibility and mechanical strength. Moreover, the pore structure of this metal membrane material is regular and orderly, with a uniform pore size distribution. Furthermore, the pore structure can be precisely controlled by adjusting the metal mesh count, the number of metal mesh layers, the electrodeposition process, and the sintering process. These advantages enable the tubular porous metal membrane material to be used in the fields of wastewater treatment, dust filtration, membrane catalytic reactors, catalytic oxidation membrane substrates and composite membrane supports, especially in extreme environments such as high temperature and high pressure.

[0017] Beneficial effects

[0018] (1) The metal film provided by the present invention has better flexibility and mechanical strength than the metal film of traditional powder sintering. At the same time, the pore structure is regular and orderly, and the pore size distribution is uniform, precise and controllable, which has a broader application prospect.

[0019] (2) The metal film preparation process provided by the present invention is simple, requires no complex equipment, greatly reduces production costs, and facilitates industrial production. Detailed Implementation

[0020] The following non-limiting embodiments are intended to enable those skilled in the art to more fully understand the present invention, but do not limit the invention in any way.

[0021] Example 1

[0022] Cut 200-mesh plain weave stainless steel mesh into rectangles with a length × width of 10 × 10 cm. Set the hydraulic system of the plate rolling machine to a working pressure of 0.5 MPa and a rolling speed of 0.3 m / min. Place the stainless steel mesh into the plate rolling machine and roll it into a tight tubular structure with a diameter of 5 mm and a wall thickness of 0.5 mm.

[0023] Using a rolled tubular multilayer stainless steel mesh as the cathode and graphite as the anode, electrodeposition was performed in a 0.5M ferrous chloride solution for 60 min at a voltage of 5V to obtain a tubular precursor film. The obtained precursor film was then subjected to high-temperature sintering in a tube furnace under an argon atmosphere, with the temperature increased to 1200℃ at a rate of 5℃ / min and held at that temperature for 5 h. After natural cooling to room temperature, a tubular porous stainless steel film was obtained.

[0024] The tubular porous stainless steel membrane successfully prepared in this embodiment has an average equivalent diameter of 3.2 μm and a porosity of 56.8%. This metal membrane can be used for dust removal from high-temperature flue gas.

[0025] Example 2

[0026] Cut a 350-mesh twill woven nickel mesh into a rectangle with a length × width of 50 × 10 cm. Set the working pressure of the hydraulic system of the plate rolling machine to 1 MPa and the rolling speed to 0.5 m / min. Place the nickel mesh into the plate rolling machine and roll it into a tight tubular structure with a diameter of 10 mm and a wall thickness of 3.2 mm.

[0027] Using a rolled tubular multilayer nickel mesh as the cathode and a pure nickel plate as the anode, electrodeposition was performed in a 0.8M nickel sulfate solution for 30 min at a voltage of 10V to obtain a tubular precursor film. The obtained precursor film was then subjected to high-temperature sintering in a tube furnace under a nitrogen atmosphere, with the temperature increased to 1000℃ at a rate of 3℃ / min and held for 4 h. After natural cooling to room temperature, a tubular porous nickel film was obtained.

[0028] The tubular porous stainless steel membrane successfully prepared in this embodiment has an average equivalent pore diameter of 1.6 μm and a porosity of 41.3%. This metal membrane can be used as a support for gas separation membranes.

[0029] Example 3

[0030] Cut a 400-mesh contrast braided copper mesh into a rectangle with a length × width of 40 × 30 cm. Set the working pressure of the hydraulic system of the plate rolling machine to 0.7 MPa and the rolling speed to 0.4 m / min. Place the copper mesh into the plate rolling machine and roll it into a tight tubular structure with a diameter of 8 mm and a wall thickness of 2.9 mm.

[0031] Using a rolled tubular multilayer copper mesh as the cathode and high-purity copper as the anode, electrodeposition was performed in a 0.5M copper nitrate solution for 90 min at a voltage of 6V to obtain a tubular precursor film. The obtained precursor film was then subjected to high-temperature sintering in a tube furnace under a mixed atmosphere of 5% hydrogen and 95% argon. The temperature was increased to 950℃ at a rate of 2℃ / min and held for 3 hours. After natural cooling to room temperature, a tubular porous copper film was obtained.

[0032] The tubular porous copper membrane successfully prepared in this embodiment has an average equivalent diameter of 0.8 μm and a porosity of 44.3%, and can be used as a base membrane for electro-Fenton catalytic membranes.

[0033] Example 4

[0034] Cut a 325-mesh plain weave titanium mesh into a rectangle with a length × width of 20 × 8 cm. Set the working pressure of the hydraulic system of the plate rolling machine to 0.6 MPa and the rolling speed to 0.6 m / min. Place the titanium mesh into the plate rolling machine and roll it into a compact tubular structure with a diameter of 7 mm and a wall thickness of 1.5 mm.

[0035] Using a rolled tubular multilayer titanium mesh as the cathode and a graphite rod as the anode, electrodeposition was performed in a 1.0M titanium chloride solution for 50 min at a voltage of 15V to obtain a tubular precursor film. The obtained precursor film was then subjected to high-temperature sintering in a tube furnace under an argon atmosphere, with the temperature increased to 1100℃ at a rate of 5℃ / min and held at that temperature for 3 h. After natural cooling to room temperature, a tubular porous titanium film was obtained.

[0036] The tubular porous titanium membrane successfully prepared in this embodiment has an average equivalent pore diameter of 1.4 μm and a porosity of 35.6%, and can be used as a substrate for electrocatalytic oxidation membranes.

[0037] Example 5

[0038] Cut 600-mesh plain weave stainless steel mesh into two rectangles with a length × width of 5 × 8 cm, and cut 200-mesh plain weave stainless steel mesh into rectangles with a length × width of 10 × 8 cm. Set the working pressure of the hydraulic system of the plate rolling machine to 0.5 MPa and the rolling speed to 1 m / min. Put the three stainless steel meshes into the plate rolling machine in the order of 600 mesh, 200 mesh and 600 mesh, and roll them into a tight tubular structure with a diameter of 10 mm and a wall thickness of 1.2 mm.

[0039] Using a rolled tubular multilayer stainless steel mesh as the cathode and a graphite rod as the anode, electrodeposition was performed in a 1.5M ferrous nitrate solution for 30 min at a voltage of 4V to obtain a tubular precursor film. The obtained precursor film was then subjected to high-temperature sintering in a tube furnace under a mixed atmosphere of 2% hydrogen and 98% argon. The temperature was increased to 1100℃ at a rate of 3℃ / min and held for 2 h. After natural cooling to room temperature, a tubular porous stainless steel film was obtained.

[0040] The tubular porous stainless steel membrane successfully prepared in this embodiment has an asymmetrical cross-section. The inner and outer sides of the membrane tube have relatively dense separation layers, and the middle is a macroporous support layer. The average diameter of the membrane pores is 0.5 μm, and the porosity is 42.5%. It can be used for filtering bacteria and suspended solids in water.

Claims

1. A tubular porous metal membrane, characterized in that: The tubular porous metal membrane is prepared from metal mesh through mechanical winding, electrodeposition anchoring, and high-temperature sintering processes. The specific steps are as follows: (1) Using metal mesh as raw material, the metal mesh is rolled into a tubular structure by a thin plate rolling machine, and then anchored by cathodic electrodeposition of metal elements to obtain a tubular precursor film. (2) The tubular precursor film is placed in an inert or reducing atmosphere and sintered at high temperature to obtain a tubular porous metal film. The preparation process of the tubular precursor membrane includes: (1) Cut the metal mesh into rectangles, place them in a thin plate rolling machine, set the rolling machine parameters, and roll them into a dense tubular structure; (2) The rolled tubular multilayer metal mesh is placed in an electrolyte, and the tubular multilayer metal mesh is used as the cathode. The metal mesh is anchored between the mesh surfaces by electrodeposition of metal elements to obtain a tubular precursor film. The rolling conditions are as follows: the working pressure of the plate rolling machine is 0~20 MPa, the rolling speed is 0.1~80 m / min; the inner diameter of the rolled tubular precursor film is 0.5~80 mm, and the wall thickness is 0.1~30 mm. The electrolyte is a solution containing one or more of the following: nitrates, sulfates, oxalates, carbonates, chlorides, and fluorides, which contain the metal element corresponding to the metal mesh. The deposition voltage is 0.4~20 V, and the deposition time is 1~600 min; The sintering process of the tubular precursor film is as follows: the obtained tubular precursor film is placed in an inert or reducing protective gas atmosphere and subjected to high-temperature sintering treatment by a programmed temperature rise method to obtain a tubular porous metal film. The protective gas is one or more of nitrogen, argon, helium, hydrogen, and carbon monoxide. The programmed heating rate is 0.01~50 ℃ / min, the final sintering temperature is 800~1800 ℃, the isothermal time is 0.1~8.0 h, and the temperature is allowed to drop naturally to room temperature after the program is completed to obtain a tubular porous metal film. The porous metal membrane has an outer diameter of 1 to 100 mm, an average pore size of 0.1 to 20.0 μm, and a porosity of 20% to 60%.

2. The tubular porous metal membrane according to claim 1, characterized in that: The metal mesh is one of stainless steel mesh, iron mesh, copper mesh, titanium mesh, tungsten mesh, molybdenum mesh, and silver mesh; The metal mesh is woven in one of the following ways: plain weave, twill weave, and reverse weave. The mesh size of the metal mesh is 20 to 1000 mesh.

3. The tubular porous metal membrane according to claim 1, characterized in that: The metal film has an ordered pore structure and a uniform pore size distribution. Furthermore, the pore structure can be precisely controlled by adjusting the mesh number, number of layers, electrodeposition process, and sintering process of the raw metal.

4. The tubular porous metal membrane according to claim 1 or 3, characterized in that: Asymmetric porous metal membranes can be prepared by splicing together metal meshes of different mesh sizes as raw materials.

5. The tubular porous metal membrane according to claim 1, characterized in that: The porous metal membrane can be used for wastewater treatment, dust filtration, membrane catalytic reactors, catalytic oxidation membrane base membranes, or composite membrane supports.