Preparation method of lanthanum cerate for reflective thermal insulation coating
By combining a molecular mixing reactor and a pressurized autoclave, along with inexpensive raw materials and dispersants, the problems of large particle size and high cost in the preparation of lanthanum cerate have been solved, enabling the low-cost preparation of nano-sized lanthanum cerate and improving the performance and industrial production efficiency of reflective heat-insulating coatings.
Patent Information
- Application Number
- CN202511389526.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-26
- Publication Date
- 2026-02-13
AI Technical Summary
Existing methods for preparing lanthanum cerate have problems such as large particle size, high production cost, and uneven mixing, which affect the performance of reflective heat-insulating coatings and industrial production efficiency.
A process combining a molecular mixing reactor and a pressurized autoclave was employed, along with dispersants such as sodium dodecylbenzenesulfonate, polyethylene glycol, and polyvinylpyrrolidone. Inexpensive lanthanum carbonate and lanthanum carbonate were used as raw materials, and nano-sized lanthanum cerium cerate was prepared by uniformly mixing the lanthanum and cerium ions with a precipitant.
This achievement enables uniform mixing and low-cost production of nano-sized lanthanum cerate, improving the performance and production efficiency of reflective heat-insulating coatings.
Smart Images
Figure CN121516901A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the rare earth hydrometallurgy technical field, more particularly to a preparation method of lanthanum cerate for reflective thermal insulation coating. BACKGROUND
[0002] Reflective thermal insulation coating is a new type of functional coating, which can enhance the reflection of sunlight while meeting the decorative performance of the substrate, thereby reducing the absorption of solar thermal radiation by buildings, effectively preventing heat conduction, reducing the surface temperature of the building and the indoor environment temperature, and playing a role in reducing the energy consumption of the building. A new type of thermal insulation coating developed by the American Solar Energy Company can reduce the indoor temperature by 5.5-14.5℃ in hot summer, thus saving 8%-12% of the related refrigeration cost per year, and in winter, the coating can also prevent the indoor heat from spreading outward, thus saving 1%-2% of the heating cost.
[0003] Lanthanum cerate is a stable fluorite structure with high thermal stability, low thermal conductivity and unique electronic layer structure, and is therefore used as a pigment filler in near-infrared reflective thermal insulation coating. At present, the preparation methods of lanthanum cerate commonly involve solid phase method, sol-gel method, liquid phase method, and pressurized hydrothermal method. The solid phase method is the most common method, which involves mixing and grinding several raw materials and then calcining them in a calcining furnace to obtain the product. Although the solid phase method is simple, the prepared particles are relatively large, which has a great influence on the reflectivity of the pigment. The raw materials required in the sol-gel method involve organic salts, which greatly increase the production cost in industrial production, and therefore are not conducive to industrial production. Both the liquid phase method and the pressurized hydrothermal method have problems such as local excess of alkali and uneven mixing during the mixing of the material liquid and the precipitant.
[0004] Therefore, the present application is proposed in view of the problems of large particles in the solid phase method, local excess of mixing alkali and uneven mixing in the liquid phase method, and high cost of raw materials and organic salts in the sol-gel method. SUMMARY
[0005] Therefore, the present application provides a preparation method of lanthanum cerate for reflective thermal insulation coating, and provides a preparation method of ultra-white, full-rare earth and low-cost lanthanum cerate.
[0006] The present application adopts a combined process of molecular mixing reactor (high gravity) and pressurized kettle (aging reaction), and uses sodium dodecyl benzene sulfonate, polyethylene glycol and polyvinylpyrrolidone as dispersants, so as to overcome the problems of large particles in the solid phase method and local excess of mixing alkali in the liquid phase method, realize uniform mixing of the precipitant and lanthanum cerium ions, and prepare nanoscale lanthanum cerate; and uses lanthanum cerium carbonate, lanthanum carbonate, ammonia and ammonium bicarbonate as the main raw materials of the process, so as to reduce the production cost from the raw materials.
[0007] To achieve the above object, the present application provides a preparation method of lanthanum cerate for reflective thermal insulation coating, comprising the following steps:
[0008] (1) dissolving mixed lanthanum cerium carbonate in nitric acid to prepare a lanthanum cerium nitrate solution, dissolving lanthanum carbonate in nitric acid to prepare a lanthanum nitrate solution, and mixing the lanthanum cerium nitrate solution and the lanthanum nitrate solution to obtain a mixed lanthanum cerium nitrate solution A;
[0009] (2) dissolving a dispersant in water, alcohol or an alcohol-water solution to obtain a dispersant B, and pouring the dispersant B into the solution A to obtain a pretreated mixed lanthanum cerium nitrate solution C;
[0010] (3) passing the solution C and a precipitant through a molecular mixer (ultra-gravity reactor) in parallel flow to obtain an amorphous lanthanum cerate precursor solution D;
[0011] (4) pouring the solution D into an aging kettle (and adding a certain amount of alcohol, water or an alcohol-water mixed solution) to perform hydrothermal aging, and then performing water washing, filtering and drying to obtain a lanthanum cerium compound E before calcination;
[0012] (5) performing high-temperature calcination on the lanthanum cerium compound E to obtain a nanoscale, full-rare earth and low-cost lanthanum cerate F.
[0013] Further, in the step (1), the concentration of the mixed lanthanum cerium nitrate solution A is 50 g / L-300 g / L (calculated based on REO), and the molar ratio of lanthanum to cerium is 1:1-1.1:1.
[0014] Further, in the step (2), the dispersant B is at least one of a dispersant dissolved in water, an organic solvent (including alcohol, alkane, ester); the dispersant includes at least one of an anionic dispersant, a cationic dispersant and a non-ionic dispersant; and the amount of the dispersant B is 1%-3% of the total amount of rare earth (REO) in the solution.
[0015] Preferably, the dispersant is at least one of sodium dodecyl benzene sulfonate, polyethylene glycol and polyvinylpyrrolidone.
[0016] Further, in the step (2), the concentration of the mixed lanthanum cerium nitrate solution C is 50 g / L-300 g / L.
[0017] Further, in the step (2), the reaction temperature of the mixing is 50°C-80°C, and the reaction time is 0.5 h-2 h.
[0018] Further, in the step (3), the precipitant used is a mixed precipitant of ammonium bicarbonate and ammonia water, and the molar ratio of NH4 + in the ammonium bicarbonate and ammonia water is 1:0-1:1, and the parallel flow speed of the solution C and the precipitant is 0.2 m 3 / h~1.2m 3 / h, the molecular mixing reactor is a high gravity reactor.
[0019] Further, in step (3), the reaction formula of the precipitant and the material liquid C is:
[0020] Ce 3+ +3OH - =Ce(OH)3 1-1
[0021] La 3+ +3OH - =La(OH)3 1-2
[0022]
[0023] Further, in step (3), the amount of the precipitant used is 1:3-1:4.5 times the molar ratio of the total cations to the total anions in the chemical formula 1-1-1-8.
[0024] Further, in step (4), the reaction temperature of the hydrothermal aging is 25-200 DEG C, the reaction time is 1-3 hours, and the washing solution is an alcohol, water or alcohol-water mixed solution.
[0025] Further, in step (5), the calcination reactor used is a roller kiln, and the calcination system is: the preheating stage is room temperature-300 DEG C, the decomposition stage is 300 DEG C-900 DEG C, and the high-temperature firing stage is 900 DEG C-1400 DEG C.
[0026] The lanthanum cerate prepared by the application is suitable for the technical field of rare earth hydrometallurgy special rare earth compounds.
[0027] The application uses lanthanum cerium carbonate and lanthanum carbonate as cerium and lanthanum sources, dissolves with nitric acid as a solvent, precipitates with light ammonium carbonate and ammonia, uses a high gravity efficient mixer as a precipitation device, uses a pressurized reactor as an aging device, and adds an organic solvent and a dispersant in the reaction system. Under the above raw materials, equipment, process conditions and process flow, the application has the following beneficial effects:
[0028] (1) The application uses cheap lanthanum cerium carbonate raw materials, which reduces the production cost, so the application has the characteristics of low cost.
[0029] (2) The application uses a high gravity molecular mixing reactor, a pressurized reactor and an organic solvent and a dispersant in combination, and the prepared nanoscale lanthanum cerate powder has good dispersibility (the particle size of the lanthanum cerate product is about 200 nm, and the shape is a spherical type, see Figure 3 , so the application has the characteristics of preparing nanoscale powder products.
[0030] (3) The raw materials used in this invention are all rare earth elements, so the products of this invention have the characteristics of being entirely rare earth. Attached Figure Description
[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.
[0032] Figure 1 This is a process flow diagram for preparing lanthanum cerate according to an embodiment of the present invention;
[0033] Figure 2 The product diagram is obtained from an embodiment of the present invention;
[0034] Figure 3 This is a scanning electron microscope image of lanthanum cerate obtained in this invention;
[0035] Figure 4 The image shows the XRD (X-ray diffraction) pattern of lanthanum cerate obtained in this invention.
[0036] Figure 5 This is a scanning electron microscope image of the lanthanum cerate precursor in an embodiment of the present invention. Detailed Implementation
[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0038] Example 1: A method for preparing lanthanum cerate for reflective heat-insulating coatings
[0039] (1) The lanthanum and cerium raw materials used are lanthanum and cerium carbonate, and the solvent is nitric acid. A lanthanum and cerium nitrate solution A is prepared with a total rare earth element (REO) of 200 g / L and a cerium-lanthanum ratio (molar ratio) of 1.05:1. The dispersant used is polyvinylpyrrolidone, which is used at 1.4% of the total rare earth element (REO). The solvent is a mixture of ethanol and water (volume ratio of water to ethanol is (4:6)). The solution B obtained after the dispersant is completely dissolved is added to the lanthanum and cerium nitrate solution A and stirred and mixed at 60°C for 1 h to prepare a pretreated mixed lanthanum and cerium nitrate solution C with a REO of 150 g / L and a cerium-lanthanum ratio (molar ratio) of 1.05:1.
[0040] (2) The pretreated lanthanum nitrate cerium nitrate solution C and the precipitant (a mixture of ammonium bicarbonate and ammonia water, both containing NH4) are added. + The molar ratio is 2:1) and they are respectively in 0.5m 3 A flow rate of / h was used to pass the lanthanum cerate precursor solution D through a molecular mixing reactor (hypergravity reactor) to obtain the lanthanum cerate precursor solution.
[0041] (3) The obtained lanthanum cerate precursor solution and an equal volume of alcohol-water solvent (the volume ratio of anhydrous ethanol to deionized water is 1:1) were added to the aging kettle and aged at 150°C for 2 hours. After the reaction was completed, the mixture was washed with water, filtered and dried to obtain the lanthanum cerium compound E before calcination.
[0042] (4) The obtained lanthanum-cerium compound E was calcined. The calcination process was as follows: preheating stage at room temperature to 300°C, decomposition stage at 300°C to 900°C, and high-temperature calcination stage at 900°C to 1200°C. Finally, an ultra-white, all-rare-earth, low-cost lanthanum cerate product was obtained.
[0043] Example 2: A method for preparing lanthanum cerate for reflective heat-insulating coatings
[0044] (1) The lanthanum and cerium raw materials used are lanthanum and cerium carbonate, and the solvent is nitric acid. A lanthanum and cerium nitrate solution A is prepared with a total rare earth element (REO) of 250 g / L and a cerium-lanthanum ratio (molar ratio) of 1.1:1. The dispersant used is polyvinylpyrrolidone, which is used at 1.2% of the total rare earth element (REO). The solvent is a mixture of ethanol and water (volume ratio of water to ethanol is (5:5)). The solution B obtained after the dispersant is completely dissolved is added to the lanthanum and cerium nitrate solution A and stirred and mixed at 60°C for 1 h to prepare a pretreated mixed lanthanum and cerium nitrate solution C with a REO of 180 g / L and a cerium-lanthanum ratio (molar ratio) of 1.1:1.
[0045] (2) The pretreated lanthanum nitrate cerium nitrate solution C and the precipitant (a mixture of ammonium bicarbonate and ammonia water, both containing NH4) are added. + The molar ratio is 4:3) with 0.7m 3 A flow rate of / h was used to pass the lanthanum cerate precursor solution D through a molecular mixing reactor (a self-made supergravity reactor) to obtain the lanthanum cerate precursor solution.
[0046] (3) The obtained lanthanum cerate precursor solution and an equal volume of alcohol-water solvent (the volume ratio of anhydrous ethanol to deionized water is 1:1) were added to the aging kettle and aged at 180°C for 3 hours. After the reaction was completed, the mixture was washed with water, filtered and dried to obtain the lanthanum cerium compound E before calcination.
[0047] (4) The obtained lanthanum-cerium compound E was calcined. The calcination process was as follows: preheating stage at room temperature to 300°C, decomposition stage at 300°C to 900°C, and high-temperature calcination stage at 900°C to 1300°C. Finally, an ultra-white, all-rare-earth, low-cost lanthanum cerate product was obtained.
[0048] Example 3: A method for preparing lanthanum cerate for reflective heat-insulating coatings
[0049] (1) The lanthanum and cerium raw materials used are lanthanum and cerium carbonate, and the solvent is nitric acid. A lanthanum and cerium nitrate solution A is prepared with a REO (total rare earth content) of 180 g / L and a cerium-lanthanum ratio (molar ratio) of 1:1. The dispersant used is polyvinylpyrrolidone, which accounts for 2.1% of the total rare earth content (REO). The solvent is a mixture of ethanol and water (volume ratio of water to ethanol is (6:4)). Solution B obtained after the dispersant is completely dissolved is added to lanthanum and cerium nitrate solution A and stirred and mixed at 60°C for 2 h to prepare a pretreated mixed lanthanum and cerium nitrate solution C with a REO of 110 g / L and a cerium-lanthanum ratio (molar ratio) of 1:1.
[0050] (2) The pretreated lanthanum nitrate cerium nitrate solution C and the precipitant (a mixture of ammonium bicarbonate and ammonia water, both containing NH4) are added. + The molar ratio is 1:1) and they are respectively in 0.8m 3 A flow rate of / h was used to pass the lanthanum cerate precursor solution D through a molecular mixing reactor (a self-made supergravity reactor) to obtain the lanthanum cerate precursor solution.
[0051] (3) The obtained lanthanum cerate precursor solution and an equal volume of alcohol-water solvent (the volume ratio of anhydrous ethanol to deionized water is 1:1) were added to the aging kettle and aged at 200℃ for 1.5h. After the reaction was completed, the mixture was washed with water, filtered and dried to obtain the lanthanum cerium compound E before calcination.
[0052] (4) The obtained lanthanum-cerium compound E was calcined. The calcination process was as follows: preheating stage at room temperature to 300°C, decomposition stage at 300°C to 900°C, and high-temperature calcination stage at 900°C to 1100°C. Finally, an ultra-white, all-rare-earth, low-cost lanthanum cerate product was obtained.
[0053] Example 4: A method for preparing lanthanum cerate for reflective heat-insulating coatings
[0054] (1) The lanthanum and cerium raw materials used are lanthanum and cerium carbonate, and the solvent is nitric acid. A lanthanum and cerium nitrate solution A is prepared with a REO (total rare earth content) of 180 g / L and a cerium-lanthanum ratio (molar ratio) of 1:1. The dispersant used is polyvinylpyrrolidone, which is used at 2.5% of the total rare earth content (REO). The solvent is a mixture of ethanol and water (volume ratio of water to ethanol is (6:4)). The solution B obtained after the dispersant is completely dissolved is added to the lanthanum and cerium nitrate solution A and stirred and mixed at 60°C for 2 h to prepare a pretreated mixed lanthanum and cerium nitrate solution C with a REO of 110 g / L and a cerium-lanthanum ratio (molar ratio) of 1:1.
[0055] (2) Use a precipitant (a mixture of ammonium bicarbonate and ammonia water, both containing NH4) + The precipitant (with a molar ratio of 1:1) was added dropwise to the pretreated lanthanum nitrate cerium solution C. After the precipitant was added, the solution was aged at 80°C for 4 hours. After aging, the solution was filtered, washed, and dried to obtain the lanthanum cerate precursor.
[0056] (3) The obtained lanthanum cerate precursor was calcined. The calcination regime was as follows: preheating stage at room temperature to 300℃, decomposition stage at 300℃ to 900℃, and high-temperature calcination stage at 900℃ to 1100℃. (See the scanning electron microscope image of the obtained lanthanum cerate precursor.) Figure 5 ,from Figure 5 As can be seen, when the method used in this invention patent is not employed, the lanthanum cerate powder obtained has a plate-like structure.
[0057] The XRD pattern shows that the chemical formula of the product is Ce2La2O7, the SEM image shows that the microstructure of the product is composed of particles with a diameter of 200 nm, and the physical image shows that the product is white. Therefore, the product of this invention has the characteristics of being ultra-white, entirely rare earth, and low-cost.
[0058] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A method for preparing lanthanum cerate for reflective heat-insulating coatings, characterized in that, Includes the following steps: (1) Dissolve lanthanum carbonate in nitric acid to prepare lanthanum nitrate solution, then dissolve lanthanum carbonate in nitric acid to prepare lanthanum nitrate solution, and finally mix the lanthanum nitrate solution with the lanthanum nitrate solution to obtain lanthanum nitrate mixed solution A; (2) Prepare dispersant B, pour dispersant B into solution A and mix to obtain pretreated mixed lanthanum cerium nitrate solution C; (3) Pass the feed solution C and the precipitant through a molecular mixer in parallel to obtain the amorphous lanthanum cerate precursor feed solution D; (4) The liquid material D is subjected to hydrothermal aging, followed by washing, filtration and drying to obtain lanthanum-cerium compound E before calcination; (5) Lanthanum-cerium compound E was calcined at high temperature to obtain nano-sized lanthanum cerate F.
2. The method for preparing lanthanum cerate for reflective heat-insulating coatings according to claim 1, characterized in that, In step (1), the concentration of the lanthanum and cerium nitrate mixed solution A is 50 g / L to 300 g / L, wherein the molar ratio of lanthanum to cerium is 1:1 to 1.1:
1.
3. The method for preparing lanthanum cerate for reflective heat-insulating coatings according to claim 1, characterized in that, In step (2), the dispersant B is at least one of a dispersant dissolved in water or an organic solvent; the dispersant includes at least one of anionic dispersant, cationic dispersant, and nonionic dispersant; the amount of dispersant B is 1% to 3% of the total rare earth content in the liquid.
4. The method for preparing lanthanum cerate for reflective heat-insulating coatings according to claim 1, characterized in that, In step (2), the concentration of the lanthanum cerium nitrate solution C is 50 g / L to 300 g / L.
5. The method for preparing lanthanum cerate for reflective heat-insulating coatings according to claim 1, characterized in that, In step (2), the reaction temperature of the mixture is 50℃~80℃ and the reaction time is 0.5h~2h.
6. The method for preparing lanthanum cerate for reflective heat-insulating coatings according to claim 1, characterized in that, In step (3), the precipitant used is a mixture of ammonium bicarbonate and ammonia, wherein the ammonium bicarbonate and ammonia contain NH4+. + The molar ratio is 1:0 to 1:1, and the co-flow velocity of the feed liquid C and the precipitant is 0.2 m / s. 3 / h~1.2m 3 / h.
7. The method for preparing lanthanum cerate for reflective heat-insulating coatings according to claim 1, characterized in that, In step (3), the chemical formula for the reaction between the precipitant and the feed solution C is: What 3+ +3OH - =Ce(OH)3 1-1 La 3+ +3OH - La(OH)3 1-2 8. The method for preparing lanthanum cerate for reflective heat-insulating coatings according to claim 7, characterized in that, In step (3), the amount of precipitant used is 1:3 to 1:4.5 times the molar ratio of the total cations to the total anions in the chemical formulas 1-1 to 1-8.
9. The method for preparing lanthanum cerate for reflective heat-insulating coatings according to claim 1, characterized in that, In step (4), the hydrothermal aging reaction temperature is 25℃~200℃ and the reaction time is 1h~3h. The water washing solution is an alcohol, water or a mixture of alcohol and water.
10. The method for preparing lanthanum cerate for reflective heat-insulating coatings according to claim 1, characterized in that, In step (5), the calcination process is as follows: the preheating stage is room temperature to 300°C, the decomposition stage is 300°C to 900°C, and the high-temperature firing stage is 900°C to 1400°C.