A multilayer co-fired alumina ceramic flat plate support body, a preparation method and application thereof

Abstract

The present application relates to the technical field of porous ceramic material preparation, in particular to a multilayer co-fired alumina ceramic flat plate support and a preparation method thereof. The method obtains the bottom layer, the transition layer and the top layer of the ceramic membrane support by sequentially pressing under the condition of gradient pressure through the molding technology, and finally obtains the required support through drying and one-time co-firing, which is simple and easy to operate. By controlling the composition of the membrane layer material and adjusting the gradient change of the particle size of the aggregate of each layer, the porosity and pore size of different layers are effectively adjusted, the pore size of the prepared ceramic flat plate support gradually increases from the top layer to the bottom layer, which can reduce the filtration resistance and increase the filtration flux. The flat plate ceramic membrane prepared by the present application improves the interface bonding strength of different membrane layers, solves the problems of mismatching of multilayer membrane co-firing shrinkage, large product warping deformation, low water flux and other technical performance, has the comprehensive performance of short production process, low preparation cost, high membrane separation precision and the like, and is suitable for large-scale production and application.

Description

Technical Field

[0001] This invention relates to the field of porous ceramic material preparation technology, specifically to a multilayer co-fired alumina ceramic plate support and its preparation method. Background Technology

[0002] In the field of advanced membrane separation materials, inorganic flat ceramic membranes have advantages such as high temperature resistance, chemical corrosion resistance, high mechanical strength after sintering, and can be recycled and reused. They also have advantages such as simple separation process, low energy consumption, easy operation and maintenance, and long service life. Their application is becoming increasingly widespread at home and abroad.

[0003] Inorganic flat-plate ceramic membranes consist of a functional membrane for separation and a support for mechanical support. The commonly used preparation method is a multi-step process. First, a support with a macroporous structure is prepared using processes such as extrusion molding, particle stacking, and foaming, giving the material high mechanical strength. Then, a layer of ceramic slurry is uniformly coated onto the surface of the support using processes such as spraying and impregnation, forming a microporous membrane. However, this preparation method still has some problems in preparation and application: 1. In order to ensure that the ceramic fine powder slurry covers the support surface as effectively and uniformly as possible, most of the current methods use the preparation of a thin transition layer to prevent the support from becoming more filtration-resistant due to the blockage of fine powder particles (refer to patent CN115073202A). However, this method requires multiple sintering, which is complicated and time-consuming, resulting in expensive inorganic membrane production costs; 2. Since the ceramic membrane support and the ceramic membrane transition layer usually need to undergo two firing processes, the bonding strength between the ceramic membrane transition layer and the support is not high due to the physicochemical compatibility between the membrane layers and the particle contact conditions; 3. Due to the mismatch of the coefficients of thermal expansion between the support and the transition layer, physical stress and thermal stress are generated during drying and sintering, which leads to sample deformation and affects the bonding strength between the transition layer and the support, as well as its service life in high-temperature environments.

[0004] Patent CN104174298A discloses a gradient silicon carbide ceramic membrane for water purification. The intermediate layer and the separation layer are prepared by dip coating on the support layer. The resulting ceramic membrane has high interconnected porosity and gradient pore distribution. However, the membrane preparation process involves the preparation of slurries for the intermediate layer and the separation layer. The slurry contains a large amount of organic polymers, which will release gases that are harmful to the environment during the firing process. Moreover, the entire membrane preparation process requires two drying steps and three sintering steps, which is complex and time-consuming.

[0005] Xu Lei et al. obtained a ceramic ultrafiltration membrane with a gradient pore structure by sequentially impregnating and coating a microporous transition membrane and an ultrafiltration membrane onto a porous alumina substrate, followed by multiple impregnation, coating, and sintering processes (Reference: Xu Lei, Ren Jiale, Li Zijin et al. Preparation and characterization of alumina ultrafiltration membrane with gradient pore structure [J]. Chinese Ceramics, 2016, 52(01):40-44.). Although the ceramic membrane prepared by this method has a gradient pore structure, there are still large pores in the membrane layer, and the preparation process is complex and time-consuming, requiring the use of functional auxiliary materials such as controlled drying chemical additives, and the process conditions are extremely strictly controlled.

[0006] Yulong Yang et al. prepared a flat-sheet ceramic membrane using a one-step pasting method. First, a self-made porous alumina membrane with a pore size of 4 μm and a porosity of 36% was used as the support. Then, alumina particles (W0.2) were uniformly mixed with other additives in a specific ratio, and the mixture was vacuum-treated for later use. Next, a plastic clay sheet was prepared using a rolling method. The plastic clay sheet was then pasted onto the surface of the support, and the sample was dried overnight in an oven at 80℃ and sintered at 1350℃ for 2 hours to obtain the flat-sheet ceramic membrane (Reference: Yanga Y, Hua Z, Changa Q, et al. One-step pasting method for preparation of flat-sheet ceramic membrane[J].Desalination and WaterTreatment,2020,196:102-109.). Although this method can produce flat ceramic membranes in one step, it requires the pre-preparation of a porous support and has high requirements for the alumina raw material of the separation layer. The required alumina particles are extremely small, which leads to high costs. In addition, the average pore size of the self-made porous support is small, which cannot achieve good processing results in applications.

[0007] Weiya Zhu et al. prepared a highly selective alumina ceramic membrane by attaching a separation layer to a support green body using a transfer coating method and sintering it at 1300℃ (Reference: Zhu W, Liu Y, Guan K, et al. Integrated preparation of alumina microfiltration membrane with super permeability and high selectivity[J]. Journal of the European Ceramic Society, 2019, 39(4):1316-1323.). This method can obtain an alumina ceramic membrane in one step, but the production process requires the separate preparation of the membrane layer and the support layer. The membrane layer is prepared by tape casting, and the support layer is prepared by dry pressing. The process is complicated, and a large amount of organic matter, such as glycerol and polyvinylpyrrolidone, needs to be added during the membrane preparation process, which will generate a large amount of harmful gases during the firing process.

[0008] Patent CN116422153A discloses a method for preparing a high-flux ceramic membrane. This method involves preparing a water-resistant transition layer on a porous ceramic membrane support, then directly coating it with a separation layer slurry, followed by drying and firing. This reduces the number of sintering steps, improves production efficiency, and lowers costs. However, the resulting support has a pore size of 3.5 μm, resulting in a low pure water flux. Furthermore, the membrane preparation process requires the addition of various functional organic polymers, leading to complex process parameters and the generation of large amounts of harmful greenhouse gases during firing.

[0009] Lijuan Huang et al. prepared slurries of different particle sizes using SiC, and formed porous SiC ceramic membrane preforms with multi-layered unidirectional gradient pore microstructures using a vacuum freeze-drying method. These preforms were then sintered at high temperature to obtain high-permeability porous SiC ceramic membranes (Reference: Huang L, Qin H, Hu T, et al. Fabrication of high permeability SiCceramic membrane with gradient pore structure by one-step freeze-casting process[J]. Ceramics International, 2021, 47(12): 17597-17605.). Although the ceramic membranes prepared by this method have a large water flux, the preparation process uses low-temperature freezing and high-temperature sintering technologies, resulting in high production costs, high energy consumption, and the emission of harmful gases, making it unsuitable for large-scale production.

[0010] Patent CN113041859A discloses a hydrophilic ceramic nanofiltration composite membrane and its preparation method. The method involves preparing a support layer through extrusion molding, followed by the preparation of two transition layers via coating. Each transition layer undergoes a calcination process. Finally, the ceramic membrane semi-finished product is continuously impregnated in a crosslinking agent and polyethyleneimine solution using an impregnation method. After a crosslinking reaction, a separation layer is formed. The resulting hydrophilic ceramic nanofiltration composite membrane exhibits good hydrophilicity, high water flux, and low molecular weight cutoff. Thickness and pore size gradients are formed between the layers, making the structure of the hydrophilic ceramic nanofiltration composite membrane more stable. However, the preparation process is complex and time-consuming, requiring multiple sintering processes and complex chemical crosslinking reactions, which is desirable to avoid for the large-scale production of advanced membrane materials. Summary of the Invention

[0011] To address the aforementioned technical problems, this invention first provides a method for preparing a multilayer co-fired alumina ceramic plate support.

[0012] The technical solution adopted in this invention is as follows:

[0013] A method for preparing a multilayer co-fired alumina ceramic plate support includes the following steps:

[0014] Step 1. Preparation of gel sintering aid:

[0015] Titanium and magnesium salts were separately prepared into solutions and then mixed. Urea solution was added, and the pH value was adjusted to 7.0-8.5 with triethanolamine or tetramethylammonium hydroxide solution. The mixture was then stirred in a water bath for a set time to obtain a mixed wet gel containing titanium and magnesium. The reaction temperature was 90-100℃ and the stirring speed was 400-500 rpm. The obtained wet gel was washed, centrifuged, and dried to obtain titanium and magnesium mixed dry gel powder, which is the desired gel sintering aid.

[0016] Step 2. Prepare the support substrate:

[0017] Alumina powder with a particle size of 90-109 μm is taken, and a pore-forming agent, a binder and a sintering aid are added to the alumina powder. After co-grinding, the powder is passed through a 100-mesh sieve to obtain a bottom layer mixed powder. The bottom layer mixed powder is molded under a pressure of 2.0-2.5 MPa to obtain a support body bottom layer green body.

[0018] Step 3. Prepare the support transition layer:

[0019] Alumina powder with a particle size of 90-109 μm and alumina powder with a particle size of 35-45 μm are mixed in a mass ratio of (6-7):1. A pore-forming agent, a binder and a sintering aid are added, and the mixture is co-milled and passed through a 150-mesh sieve to obtain a transition layer mixed powder. 35% of the mass of the transition layer mixed powder, which accounts for 35% of the mass of the bottom green body of the support body described in step 2, is weighed and covered on the bottom green body of the support body. The mixture is then molded under a pressure of 2.5-3.0 MPa to obtain a support body green body containing a transition layer.

[0020] Step 4. Prepare the top layer of the support:

[0021] Alumina powder with a particle size of 35-45 μm is mixed with a pore-forming agent and a binder, and then co-milled and passed through a 200-mesh sieve to obtain a top layer mixed powder. 30% of the top layer mixed powder, which accounts for 30% of the mass of the bottom green body of the support body described in step 2, is weighed and covered on the green body of the support body containing the transition layer. The green body of the support body is then molded under a pressure of 3.5-4.0 MPa to obtain the green body of the support body.

[0022] Step 5. First firing:

[0023] After drying the green body of the support described in step 4, a sintering process is performed to obtain the desired ceramic flat plate support.

[0024] Preferably, the raw material for the alumina powder is any one or a mixture of multiple types of powder selected from brown fused alumina, white fused alumina, bauxite, or recycled fused alumina.

[0025] Preferably, in steps 2 and 3, the amount of sintering aid added is 0.7 to 3.0 wt% of the alumina powder mass.

[0026] Preferably, the pore-forming agent is any one or a combination of white sugar, starch, and carbon powder, the average particle size of the pore-forming agent is 45-50 μm, and the amount added is 5-10 wt% of the mass of alumina powder.

[0027] Preferably, the binder is dextrin or carboxymethyl cellulose, the average particle size of the binder is 10-15 μm, and the amount added is 10-20 wt% of the alumina powder.

[0028] Preferably, the titanium salt is TiCl4, which is prepared into a solution in an ice-water bath with a titanium ion concentration of 0.5 mol / L; the magnesium salt is MgCl2·6H2O, which is prepared into a solution at room temperature with a magnesium ion concentration of 0.5 mol / L; the TiCl4 solution and the MgCl2·6H2O solution are mixed at a Mg / Ti molar ratio of 1.2.

[0029] Preferably, after mixing the TiCl4 solution and the MgCl2·6H2O solution, a urea solution is added at a volume ratio of 1:1, with a urea solution concentration of 6 mol / L.

[0030] Preferably, the drying temperature of the wet gel is 105°C and the drying time is 12 hours.

[0031] Preferably, in step 5, the drying temperature is 60°C and the drying time is 2-4 hours.

[0032] Preferably, in step 5, the sintering process is as follows: the heating rate from room temperature to 200°C is 1°C / min, and the holding time is 30min; the heating rate from 200°C to 600°C is 1°C / min, and the holding time is 30min; the heating rate from 600°C to 1000°C is 4°C / min, and then the heating rate from 1000°C to 1400°C to 1500°C is 3°C / min, and the holding time is 2h at the highest temperature; then cooling begins at a cooling rate of 5°C / min, and after cooling to 800°C, the temperature is reduced to 500°C at a cooling rate of 3°C / min, and finally cooled naturally to obtain the desired ceramic plate support.

[0033] The present invention also provides an alumina ceramic plate support prepared by the preparation method described above.

[0034] The present invention also provides the application of the alumina ceramic plate support as described above in the purification and treatment of wastewater from new energy vehicle painting and / or the treatment of textile printing and dyeing wastewater.

[0035] The beneficial effects of this invention are as follows:

[0036] This preparation method utilizes compression molding technology under gradient pressure conditions, combined with powder composition and particle size adjustment, to sequentially press the bottom layer, transition layer, and top layer of a ceramic membrane support. The desired support is then obtained through drying and a single co-firing. The process is simple, easy to operate, and low-cost. The prepared ceramic flat plate support exhibits strong interlayer bonding, a smooth surface, and a pore size gradient ranging from 10.6 μm to 0.4 μm, with a permeation flux reaching 557677.6165 L·h. -1 ·m -1 ·MPa -1 It boasts high-precision microfiltration separation and other comprehensive membrane separation performance.

[0037] This invention effectively regulates the porosity and pore size of different layers by adjusting the gradient change of aggregate particle size in different layers, so that the pore size gradually increases from the top layer inward, thereby reducing filtration resistance and increasing filtration flux.

[0038] This invention prepares a transition layer between the bottom and top layers of the support, which is a mixture of large and small particle powders in a certain proportion. This effectively adjusts the physical interface bonding strength between the bottom and top layers and extends their service life.

[0039] In addition, a specially formulated gelation aid, namely nano-sized titanium-magnesium gel powder prepared by a gelation reaction method, is added to the bottom layer and transition layer of the support. This powder is halogen-free and pollution-free, making it suitable for practical industrial production. After high-temperature sintering, this aid forms a magnesium titanate compound with negative thermal expansion characteristics, exhibiting a coefficient of thermal expansion of -1.84 × 10⁻⁶. -4 / K -1 Adding it to the bottom and transition layers of the ceramic film can effectively adjust the problem of mismatch between the top and bottom shrinkage, thereby alleviating the problem of warping and deformation of the product during heat treatment.

[0040] The ceramic raw materials used in this method are widely available, environmentally friendly, and low in cost. The added organic auxiliary materials are all natural biomass raw materials. Finally, only one firing process is used, which is more energy-efficient and emission-reducing than the multiple sintering in the existing technology. It also has high production efficiency and low production cost. Attached Figure Description

[0041] Figure 1 The diagram shows the porosity variation of the ceramic plate supports prepared in Examples 1-9.

[0042] Figure 2 The diagram shows the pore size variation of the ceramic plate supports prepared in Examples 1-9.

[0043] Figure 3 The pure water flux performance of the ceramic plate supports prepared in Examples 1-9.

[0044] Figure 4 The graph shows the warpage variation of the ceramic plate supports prepared in Examples 1-9.

[0045] Figure 5 The image shows the pore size distribution of the top layer of the ceramic plate support prepared in Example 7.

[0046] Figure 6 The image shows the pore size distribution of the transition layer of the ceramic plate support prepared in Example 7.

[0047] Figure 7 The image shows the pore size distribution of the bottom layer of the ceramic plate support prepared in Example 7.

[0048] Figure 8 The image shows a scanning electron microscope image of the cross-section of the ceramic plate support prepared in Example 7.

[0049] Example 1

[0050] A method for preparing a multilayer co-fired alumina ceramic plate support, firstly by preparing a sintering aid:

[0051] To prepare a 0.5 mol / L TiCl4 aqueous solution, 3.25 ml of TiCl4 was added dropwise to 57 ml of deionized water in an ice-water bath. 6.9 g of MgCl2·6H2O was weighed and added to 68 ml of deionized water to prepare a 0.5 mol / L MgCl2·6H2O solution. 45 g of urea was weighed and added to 125 ml of deionized water to prepare a 6 mol / L urea solution. The TiCl4 aqueous solution and the MgCl2·6H2O solution were mixed to obtain a magnesium-titanium mixture. The preheated magnesium-titanium mixture and the 6 mol / L urea solution were added at a 1:1 volume ratio to a beaker equipped with a magnetic stir bar. The mixture was then subjected to a water bath reaction at 98 °C and a stirring speed of 450 rpm. Triethanolamine was added to adjust the pH to approximately 7, and the mixture was kept at this temperature for 1 hour to obtain a wet gel. The obtained wet gel was washed, centrifuged three times with deionized water, and dried at 105℃ for 12 hours to obtain dry gel sintering aid powder for later use.

[0052] The preparation of a ceramic plate support includes the following steps:

[0053] Step 1. Prepare the support substrate:

[0054] 100g of 106μm brown corundum aggregate was weighed and 6wt% white sugar, 12wt% yellow dextrin and 0.7wt% sintering aid were added. The mixture was stirred and mixed in a ball mill for 3 hours and then passed through a 100-mesh sieve to obtain the first mixed powder. The first mixed powder was molded into a support body bottom green body using a molding process with a pressure of 2MPa.

[0055] Step 2. Prepare the support transition layer:

[0056] Brown fused alumina aggregates of different particle sizes were weighed out at a mass ratio of 106μm brown fused alumina:38μm brown fused alumina = 7:1, totaling 100g. Based on the total mass of the brown fused alumina aggregates, 6wt% white sugar, 12wt% dextrin, and 0.7wt% sintering aid were added. The mixture was stirred and mixed in a ball mill for 3 hours, then passed through a 150-mesh sieve to obtain a second mixed powder. 35% of the second mixed powder, representing 35% of the mass of the bottom green body of the support layer, was weighed and applied to the bottom green body of the support layer. A compression molding process was then used to prepare the support green body containing a transition layer, with a pressure of 3 MPa.

[0057] Step 3. Prepare the top layer of the support:

[0058] 100g of 38μm brown corundum aggregate was weighed, and 6wt% white sugar and 12wt% yellow dextrin were added. The mixture was stirred and mixed in a ball mill for 3 hours and then passed through a 200-mesh sieve to obtain the third mixed powder. 30% of the third mixed powder, accounting for 30% of the mass of the bottom green body of the support, was weighed and covered on the green body of the support containing the transition layer. The green body of the support was prepared by compression molding at a pressure of 4 MPa.

[0059] Step 4. First firing:

[0060] The green support body was placed in a 60°C oven and dried for 2 hours. After drying, the ceramic film support body was sintered using the following heat treatment procedure: heating from room temperature to 200°C at a rate of 1°C / min and holding for 30 minutes; heating from 200°C to 600°C at a rate of 1°C / min and holding for 30 minutes; heating from 600°C to 1000°C at a rate of 4°C / min; then heating from 1000°C to 1400°C at a rate of 3°C / min and holding at 1400°C for 2 hours; then cooling was started at a rate of 5°C / min, and after cooling to 800°C, the temperature was lowered to 500°C at a rate of 3°C / min, and finally allowed to cool naturally to obtain the desired ceramic flat plate support body.

[0061] Example 2

[0062] The ceramic plate support was prepared using the same method as in Example 1, except that the maximum sintering temperature was adjusted to 1450℃.

[0063] Example 3

[0064] The ceramic plate support was prepared using the same method as in Example 1, except that the maximum sintering temperature was adjusted to 1500℃.

[0065] Example 4

[0066] The ceramic plate support was prepared using the same method as in Example 1, except that tetramethylammonium hydroxide solution was used as a pH adjuster during the preparation of the sintering aid powder, and the amount of sintering aid added was adjusted to 1.5 wt%.

[0067] Example 5

[0068] The ceramic plate support was prepared using the same method as in Example 2, except that tetramethylammonium hydroxide solution was used as a pH adjuster during the preparation of the sintering aid powder, and the amount of sintering aid added was adjusted to 1.5 wt%.

[0069] Example 6

[0070] The ceramic plate support was prepared using the same method as in Example 3, except that tetramethylammonium hydroxide solution was used as a pH adjuster during the preparation of the sintering aid powder, and the amount of sintering aid added was adjusted to 1.5 wt%.

[0071] Example 7

[0072] The ceramic plate support was prepared using the same method as in Example 1, except that the amount of sintering aid added was adjusted to 3.0 wt%.

[0073] Example 8

[0074] The ceramic plate support was prepared using the same method as in Example 2, except that the amount of sintering aid added was adjusted to 3.0 wt%.

[0075] Example 9

[0076] The ceramic plate support was prepared using the same method as in Example 3, except that the amount of sintering aid added was adjusted to 3.0 wt%.

[0077] The porosity analysis results of the ceramic plate supports prepared in Examples 1-9 are shown in the figure. Figure 1 The results of the aperture variation analysis are shown in Figure 2 The results of the pure water flux analysis are shown below. Figure 3 The results of the warpage analysis are shown below. Figure 4 .

[0078] from Figure 1 , Figure 2 As can be seen from the results, with the increase of sintering temperature and the increase of sintering aid content, the porosity and pore size of the support change significantly. The porosity decreases from 44.6% to 36.4%, and the pore size decreases from 10.6μm to 7.1μm, indicating that temperature and sintering aid content have a significant impact on the porosity and pore size of the support.

[0079] from Figure 3 As can be seen, with the increase of sintering temperature and the increase of sintering aid content, the pure water flux also decreases continuously, from 557677.6165 L·h. -1 ·m -1 ·MPa -1 Decreased to 206264.3239 L·h -1 ·m -1 ·MPa -1 This phenomenon is simultaneously with Figure 1 , Figure 2 The patterns of change shown are consistent.

[0080] Figure 4 The relationship between sample warpage and sintering temperature and sintering aid content is described. As can be seen from the figure, the warpage is the lowest, only 0.44%, when the sintering aid content reaches 3wt% and the sintering temperature is 1400℃.

[0081] Analysis of the ceramic plate support prepared in Example 7 shows the pore size distribution of the top layer of the composite material. Figure 5 The pore size distribution of the composite material transition layer is shown in the figure. Figure 6 The pore size distribution of the composite material's bottom layer is shown in [the figure]. Figure 7 The fracture morphology of the composite material is shown in Figure 8 .

[0082] As can be seen from the pore size distribution diagram of different layers, the pore size in the material gradually decreases from the top layer of the support, indicating that the present invention has achieved the formation of a gradient pore structure. Further analysis shows that the minimum pore size is 0.4 μm, the average pore size is 2.5 μm, and the average pore size of the bottom layer is 9.5 μm.

[0083] Compared with commercially available flat-plate MBR ceramic membranes (Xiamen Lanbo Technology Development Co., Ltd., with an average surface pore size of 0.05μm to 0.2μm), the ceramic flat-plate support prepared by this method retains a small-pore separation layer while also having a large-pore bottom layer. It can be used for the removal of oil, microorganisms, bacteria and other impurities, and has broad application prospects in wastewater treatment, especially in the fields of new energy vehicle coating wastewater and textile printing and dyeing wastewater treatment.

[0084] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a multilayer co-fired alumina ceramic plate support, characterized in that, Includes the following steps: Step 1. Preparation of gel sintering aid: Titanium and magnesium salts were separately prepared into solutions and then mixed. Urea solution was added, and the pH value was adjusted to 7.0-8.5 with triethanolamine or tetramethylammonium hydroxide solution. The mixture was then stirred in a water bath for a set time to obtain a mixed wet gel containing titanium and magnesium. The reaction temperature was 90-100℃ and the stirring speed was 400-500 rpm. The obtained wet gel was washed, centrifuged, and dried to obtain titanium and magnesium mixed dry gel powder, which is the desired gel sintering aid. The titanium salt is TiCl4, which is prepared into a solution in an ice-water bath with a titanium ion concentration of 0.5 mol / L; the magnesium salt is MgCl2·6H2O, which is prepared into a solution at room temperature with a magnesium ion concentration of 0.5 mol / L; the TiCl4 solution and the MgCl2·6H2O solution are mixed at a Mg / Ti molar ratio of 1.2; after mixing the TiCl4 solution and the MgCl2·6H2O solution, a urea solution with a volume ratio of 1:1 and a urea solution concentration of 6 mol / L is added; Step 2. Prepare the support substrate: Alumina powder with a particle size of 90~109 μm is taken, and a pore-forming agent, a binder and a sintering aid are added to the alumina powder. After co-milling, the powder is passed through a 100-mesh sieve to obtain a bottom mixed powder. The bottom mixed powder is molded under a pressure of 2.0~2.5 MPa to obtain a support body bottom green body. Step 3. Prepare the support transition layer: Alumina powder with a particle size of 90~109 μm and alumina powder with a particle size of 35~45 μm are mixed at a mass ratio of (6~7):

1. A pore-forming agent, a binder and a sintering aid are added, and the mixture is co-milled and passed through a 150-mesh sieve to obtain a transition layer mixed powder. 35% of the mass of the transition layer mixed powder, which accounts for 35% of the mass of the bottom green body of the support body described in step 2, is weighed and covered on the bottom green body of the support body. The mixture is then molded under a pressure of 2.5~3.0 MPa to obtain a support body green body containing a transition layer. Step 4. Prepare the top layer of the support: Alumina powder with a particle size of 35~45 μm is mixed with a pore-forming agent and a binder, and then co-milled and passed through a 200-mesh sieve to obtain a top layer mixed powder. 30% of the top layer mixed powder, which accounts for 30% of the mass of the bottom green body of the support body described in step 2, is weighed and covered on the green body of the support body containing the transition layer. The green body of the support body is then molded under a pressure of 3.5~4.0 MPa to obtain the green body of the support body. Step 5. First firing: After drying the green body of the support described in step 4, a sintering process is performed to obtain the desired ceramic flat plate support. In steps 2 and 3, the amount of sintering aid added is 0.7 to 3.0 wt% of the alumina powder mass.

2. The method for preparing a multilayer co-fired alumina ceramic plate support as described in claim 1, characterized in that, The raw material for the alumina powder is any one or a mixture of multiple types of powders, including brown fused alumina, white fused alumina, bauxite, or recycled fused alumina.

3. The method for preparing a multilayer co-fired alumina ceramic plate support as described in claim 1, characterized in that, The pore-forming agent is any one or more of white sugar, starch, and carbon powder, and the average particle size of the pore-forming agent is 45~50 μm, and the amount added is 5~10 wt% of the alumina powder.

4. The method for preparing a multilayer co-fired alumina ceramic plate support as described in claim 1, characterized in that, The binder is dextrin or carboxymethyl cellulose, the average particle size of the binder is 10-15 μm, and the amount added is 10-20 wt% of the alumina powder.

5. The method for preparing a multilayer co-fired alumina ceramic plate support as described in claim 1, characterized in that, In step 5, the drying temperature is 60℃ and the drying time is 2~4 hours.

6. The method for preparing a multilayer co-fired alumina ceramic plate support as described in claim 1, characterized in that, In step 5, the sintering process is as follows: the heating rate from room temperature to 200°C is 1°C / min, and the holding time is 30min; the heating rate from 200°C to 600°C is 1°C / min, and the holding time is 30min; the heating rate from 600°C to 1000°C is 4°C / min, and then the heating rate from 1000°C to 1400°C to 1500°C is 3°C / min, and the holding time is 2 hours at the highest temperature; then the cooling process begins at a cooling rate of 5°C / min, and after cooling to 800°C, the temperature is reduced to 500°C at a cooling rate of 3°C / min, and finally the temperature is allowed to cool naturally to obtain the desired ceramic plate support.

7. An alumina ceramic plate support prepared by the preparation method according to any one of claims 1-6.

8. The application of the alumina ceramic plate support as described in claim 7 in the purification and treatment of wastewater from new energy vehicle painting and / or the treatment of wastewater from textile printing and dyeing.

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