Preparation method and application of high-stable shaped hydrotalcite and derived composite metal oxide

Abstract

The application discloses a preparation method and application of high-stable shaped hydrotalcite and derived composite metal oxide. The application obtains high-purity hydrotalcite powder by using a clean process technology, and then prepares a series of high-stable shaped hydrotalcite and derived composite metal oxide by introducing a low-concentration high-molecular stabilizer in a shaping process, optimizing process parameters such as a peptizing agent concentration, a kneading paste and a quick-release powder ratio, a water powder ratio, a hydrotalcite adding amount and the like by using a granulation continuous manufacturing technology. The application solves the problems of easy generation of byproduct impurities, low shaping strength, small specific surface and poor stability in the preparation process of the hydrotalcite and the derived composite metal oxide. The preparation process is simple, the prepared material has a higher specific surface and excellent compression crushing strength, and has good structure stability in a reaction process without obvious powder dropping and dissolving. The material can be applied to important environmental chemical industry, petroleum chemical industry and fine chemical industry processes and is easy to recycle and reuse.

Description

Technical Field

[0001] This invention belongs to the fields of environmental chemical engineering, petrochemical engineering and fine chemical engineering, and specifically relates to a method for preparing highly stable shaped hydrotalcite and its derivative composite metal oxides and their applications. Background Technology

[0002] Layered double hydroxides (LDHs) are a class of supramolecular intercalated anionic layered compounds assembled from positively charged host layers and interlayer anions through non-covalent interactions. Using LDHs as precursors, a series of highly dispersed composite oxides (LDOs) can be obtained by utilizing their structural topological properties. Due to the unique structural characteristics and rich tunability of LDHs and LDOs, introducing metal elements or groups with specific functions into the layers or interlayers can prepare intercalated functional materials with different functional properties, such as adsorbents, catalysts, PVC heat stabilizers, UV blockers, and smoke suppressants—novel green and environmentally friendly materials with applications in wastewater and waste gas treatment, catalytic conversion, rubber and plastic additives, highway construction, building materials, and petrochemicals.

[0003] However, products prepared using traditional methods (such as single-drop and double-drop methods) are prone to generating byproducts, affecting the purity of hydrotalcite and its derived composite metal oxides. Furthermore, research on hydrotalcite and its derived composite metal oxides in both basic research and industrial applications is primarily focused on powders, which are prone to clogging the reaction bed, difficult to separate after reaction, and impossible to regenerate. Therefore, molding hydrotalcite and its derived composite metal oxide powders before use would be beneficial for further expanding their application areas. However, numerous studies have shown that molding hydrotalcite and its derived composite metal oxides is difficult, and the molding process suffers from low mechanical strength, small specific surface area, and poor stability, thus limiting their large-scale application in industrial production. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing highly stable shaped hydrotalcite and derived composite metal oxides, and to use them in the removal of heavy metal ions from wastewater, desalination of cultural relics, desulfurization of flue gas, and catalytic hydrogenation processes.

[0005] The preparation method of the highly stable shaped hydrotalcite is as follows: hydrotalcite powder and a polymer stabilizer are ultrasonically dispersed in water, then fast-release powder, guar gum powder, adhesive solvent and kneading paste are added, and the mixture is stirred evenly to obtain a mixture. Then, the mixture is mechanically kneaded, and then shaped using an extruder with perforated plates of different shapes. The shaped material is then cut into strips and granulated, with a ratio of 1-2... o By heating the temperature at a rate of 60-80 °C / min and drying for 12-24 h, highly stable shaped hydrotalcites of different shapes can be obtained.

[0006] The divalent metal ions in the layers of the hydrotalcite are Mg. 2+ Ca 2+ Zn 2+ One or two of them, with trivalent metal ions being Al 3+ The molar ratio of divalent metal ions to trivalent metal ions is 2-4; the interlayer anion is Cl. - NO3 - or CO3 2- .

[0007] The polymeric stabilizer is one or more of polyethylene glycol, polyvinyl alcohol, and polyvinylpyrrolidone.

[0008] The kneading paste is boehmite or starch.

[0009] The adhesive solvent is nitric acid.

[0010] The water-to-powder ratio of the mixture is 0.33-0.50. In the mixture, the mass concentration of the polymeric stabilizer is 0.01-0.045%, and the mass concentration of nitric acid is 1-9%.

[0011] The powder raw materials in the mixture consist of hydrotalcite powder, quick-release powder, guar gum powder and kneading paste. The mass percentage of guar gum powder in the powder raw materials is 0.02-2.5%, the mass percentage of kneading paste is 1.2-14.2%, the mass percentage of quick-release powder is 5-58.3%, and the remainder is hydrotalcite powder.

[0012] The preparation method of the hydrotalcite is as follows: a soluble divalent metal compound and a soluble Al source with a molar ratio of 2-4 are weighed and dissolved in deionized water, and ultrasonically mixed evenly, wherein the solid content is 5-30 wt%, and then mixed at 80-120 °C. o The mixture is stirred and reacted at temperature C for 2-6 hours. After the reaction is complete, the slurry is centrifuged and filtered to obtain hydrotalcite free of other impurities.

[0013] The soluble Al source is Al(OH)3, boehmite, or AlCl3.

[0014] The soluble divalent metal compound is a mixture of CaCl2 and CaO with a molar ratio of 1:3-7, a mixture of CaCl2 and Ca(OH)2 with a molar ratio of 1:3-7, a mixture of MgCl2 and Ca(OH)2 with a molar ratio of 1:3-7, a mixture of CaCl2, MgCl2 and Ca(OH)2 with a molar ratio of 1:1:6-10, a mixture of MgCl2 and Mg(OH)2 with a molar ratio of 1:3-5, a mixture of CaCl2, MgCl2, Ca(OH)2 and Mg(OH)2 with a molar ratio of 1-2:1:3-7:2-3, a mixture of ZnCl2, MgCl2 and Zn(OH)2 with a molar ratio of 1:1:6-10, or a mixture of ZnCl2 and Mg(OH)2 with a molar ratio of 1:3-7.

[0015] The shaped hydrotalcite can be spherical, near-spherical, toothed, cylindrical, or clover-shaped.

[0016] The preparation method of the highly stable molded derivative composite metal oxide is as follows: the highly stable molded hydrotalcite prepared above is subjected to an oxidizing atmosphere at 450-600 °C. o C roasting for 4-10 hours.

[0017] The oxidizing atmosphere is air, oxygen, or CO2.

[0018] The heating rate of the roasting is 1-2. o C / min.

[0019] The highly stable shaped hydrotalcite and derived composite metal oxides prepared above can be used for adsorbing heavy metal ions in wastewater, desalination in cultural relic protection, flue gas desulfurization, and as catalyst carriers.

[0020] This invention employs a clean process technology, achieving 100% atomic utilization of raw materials through reaction route design to obtain high-purity hydrotalcite and its derived composite metal oxide powders without the generation of by-product impurities. It utilizes continuous granulation manufacturing technology, introducing a low-concentration polymeric stabilizer during the molding process and optimizing process parameters such as the concentration of the adhesive solvent, the ratio of kneading paste to rapid powder removal, the water-to-powder ratio, and the amount of hydrotalcite added, to prepare a series of highly stable molded hydrotalcite and its derived composite metal oxides. This method solves the problems of by-product impurities, low molding strength, small specific surface area, and poor stability that are easily generated in the preparation of hydrotalcite and its derived composite metal oxides in existing technologies. This preparation process is simple, and the resulting materials have a high specific surface area, reaching 50-170 μm. 2This material exhibits excellent crushing strength (40-100 N / particle) per g, low production cost, good structural stability during reaction, and is not easily dissolved to produce impurities such as carbonates. It also shows no significant powder shedding or leaching. This material can be applied in important environmental chemical, petrochemical, and fine chemical processes and is easily recyclable and reusable. Attached Figure Description

[0021] Figure 1 Ca2Al-Cl prepared in Example 1 - The photo shows the LDHs-N, where the hydrotalcite appears as strips after molding.

[0022] Figure 2 The Ca2Al-Cl prepared for (A) Example 1 and (B) Comparative Example 1 - The stability of -LDHs-N in aqueous solution: the hydrotalcite prepared with polymeric stabilizers and slow drying showed no obvious powdering or dissolution, while the hydrotalcite prepared in Comparative Example 1 turned milky white within 5 minutes when placed in aqueous solution.

[0023] Figure 3 The Ca2Al-Cl prepared for (A) Example 1 and (B) Comparative Example 2 - The X-ray diffraction (XRD) spectra of -LDHs-N show that hydrotalcite prepared by the clean process has no obvious by-product impurities, while hydrotalcite prepared by the urea method has magnesium carbonate impurities, which affects the strength of the molded product. Detailed Implementation Example 1

[0024] Step A. Using an atom-economical clean process, weigh 200.0 g Al(OH)3, 142.3 g CaCl2, and 215.4 g CaO according to Ca / Al = 2 / 1. Dissolve them in deionized water with a solid content of 6 wt%, ultrasonically mix thoroughly, and then... o The reaction was carried out under stirring conditions for 2 hours. After the reaction was completed, the slurry was centrifuged and filtered to obtain Ca2Al-Cl. - -LDHs hydrotalcite precursors.

[0025] Step B. Take the 6.47g Ca2Al-Cl obtained in Step A. - -LDHs powder and polyvinylpyrrolidone polymeric stabilizer were ultrasonically dispersed in water, then 15.00 g of fast-release powder, 0.60 g of guar gum powder, nitric acid and 3.66 g of boehmite were added and stirred evenly to obtain a mixture, which was then mechanically kneaded; the water-to-powder ratio in the mixture was 0.5, the mass concentration of nitric acid was 6.7%, and the mass concentration of polyvinylpyrrolidone polymeric stabilizer was 0.045%.

[0026] Step C. After forming using an extruder, the pellets are cut into strips, and the formed samples are granulated at 1... o The temperature was increased to 80℃ at a rate of C / min and dried for 12 h to obtain strip-shaped, high-purity, and high-strength shaped hydrotalcite Ca2Al-Cl. - -LDHs-N, crushing strength of 100N / particle, specific surface area of ​​166m² 2 / g. Further, it is divided into 1... o Heating rate increased to 450 °C / min o C. The shaped derivative composite metal oxide Ca2Al-LDO was obtained by calcination under CO2 atmosphere for 10 h.

[0027] 0.5 g of shaped hydrotalcite and derived composite metal oxide were weighed separately and added to 100 mL of a mixed solution containing Pb, Cd, and As heavy metal ions, respectively. After shaking for 3 hours, inductively coupled plasma atomic emission spectrometry (ICP) was performed for analysis. No obvious powder shedding or dissolution was observed during the reaction. The calculated removal rates of the three heavy metal ions by the shaped hydrotalcite were 89.5%, 12.5%, and 8.35%, respectively.

[0028] When the shaped hydrotalcite is placed in an aqueous solution and CO2 is introduced for 5 minutes, the solution becomes clear and transparent, with no obvious powder shedding or dissolution. Example 2

[0029] Step A. Using an atom-economical clean process, weigh 200.0 g Al(OH)3, 142.3 g CaCl2, and 215.4 g CaO according to Ca / Al = 2 / 1. Dissolve them in deionized water with a solid content of 6 wt%, ultrasonically mix thoroughly, and then... o The reaction was carried out under stirring conditions for 2 hours. After the reaction was completed, the slurry was centrifuged and filtered to obtain Ca2Al-Cl. - -LDHs hydrotalcite precursors.

[0030] Step B. Take 129.40g of Ca2Al-Cl obtained in Step A. - -LDHs powder and polyvinylpyrrolidone polymeric stabilizer were ultrasonically dispersed in water, then 15.00 g of fast-release powder, 0.60 g of guar gum powder, nitric acid and 3.66 g of boehmite were added and stirred evenly to obtain a mixture, which was then mechanically kneaded; the water-to-powder ratio in the mixture was 0.5, the mass concentration of nitric acid was 6.7%, and the mass concentration of polyvinylpyrrolidone polymeric stabilizer was 0.045%.

[0031] Step C. After forming using an extruder, the pellets are cut into strips, and the formed samples are granulated at 1... oThe temperature was increased to 80℃ at a rate of C / min and dried for 12 h to obtain strip-shaped, high-purity, and high-strength shaped hydrotalcite Ca2Al-Cl. - -LDHs-N, crushing strength of 57 N / particle, specific surface area of ​​55 μm. 2 / g. Further, it is divided into 1... o Heating rate increased to 450 °C / min o C. The shaped derivative composite metal oxide Ca2Al-LDO was obtained by calcination under CO2 atmosphere for 10 h.

[0032] The shaped hydrotalcite and derived composite metal oxides obtained above were used as adsorbents for the removal of As, Cd, and Pb ions from wastewater, respectively. No significant powder shedding or leaching occurred during the reaction. Calculations showed that the shaped hydrotalcite achieved a removal rate of over 99.5% for all three heavy metal ions. Example 3

[0033] Step A. Using an atom-economical clean process, weigh 200.0 g Al(OH)3, 142.3 g CaCl2, and 215.4 g CaO according to Ca / Al = 2 / 1. Dissolve them in deionized water with a solid content of 6 wt%, ultrasonically mix thoroughly, and then... o The reaction was carried out under stirring conditions for 2 hours. After the reaction was completed, the slurry was centrifuged and filtered to obtain Ca2Al-Cl. - -LDHs hydrotalcite precursors.

[0034] Step B. Take 129.40g of Ca2Al-Cl obtained in Step A. - -LDHs powder and polyvinylpyrrolidone polymeric stabilizer were ultrasonically dispersed in water, then 15.00 g of fast-release powder, 0.60 g of guar gum powder, nitric acid and 3.66 g of boehmite were added and stirred evenly to obtain a mixture, which was then mechanically kneaded; the water-to-powder ratio in the mixture was 0.5, the mass concentration of nitric acid was 6.7%, and the mass concentration of polyvinylpyrrolidone polymeric stabilizer was 0.045%.

[0035] Step C. After forming using an extruder, the pellets are cut into strips, and the formed samples are granulated at 1... o The temperature was increased to 80℃ at a rate of C / min and dried for 12 h to obtain strip-shaped, high-purity, and high-strength shaped hydrotalcite Ca2Al-Cl. - -LDHs-N, crushing strength of 57 N / particle, specific surface area of ​​55 μm. 2 / g. Further, it is divided into 1... o Heating rate increased to 450 °C / min o C. The shaped derivative composite metal oxide Ca2Al-LDO was obtained by calcination under CO2 atmosphere for 10 h.

[0036] The shaped hydrotalcite and derived composite metal oxides obtained above were used as adsorbents for the removal of Cu, Zn, Cd, and Pb ions from wastewater. No significant powder shedding or leaching occurred during the reaction. Calculations showed that the shaped hydrotalcite achieved a removal rate of over 99.5% for all four heavy metal ions. Example 4

[0037] Step A. Using an atom-economical clean process, weigh 200 g Al(OH)3, 122.1 g MgCl2, and 224.3 g Mg(OH)2 according to Mg / Al = 2 / 1. Dissolve them in deionized water to a solid content of 6 wt%, ultrasonically mix thoroughly, and then... o The reaction was carried out under stirring conditions for 2 hours. After the reaction was completed, the slurry was centrifuged and filtered to obtain Mg2Al-CO3. 2- -LDHs hydrotalcite precursors.

[0038] Step B. Take the 64.70g Mg2Al-CO3 obtained in Step A. 2- -LDHs powder and polyvinylpyrrolidone polymeric stabilizer were ultrasonically dispersed in water, then 15.00 g of fast-release powder, 0.60 g of guar gum powder, nitric acid and 3.66 g of boehmite were added and stirred evenly to obtain a mixture, which was then mechanically kneaded; the water-to-powder ratio in the mixture was 0.5, the mass concentration of nitric acid was 6.7%, and the mass concentration of polyvinylpyrrolidone polymeric stabilizer was 0.045%.

[0039] Step C. After forming using an extruder, the pellets are cut into strips, and the formed samples are granulated at 1... o The temperature was increased to 80℃ at a rate of C / min and dried for 12 h to obtain strip-shaped, high-purity, and high-strength shaped hydrotalcite Mg2Al-CO3. 2- -LDHs-N, crushing strength of 51 N / particle, specific surface area of ​​100 μm. 2 / g. Further, it is divided into 1... o Heating rate increased to 450 °C / min o C. Calcination in air atmosphere for 10 h yields the shaped derivative composite metal oxide Mg2Al-LDO.

[0040] 0.1 g of shaped hydrotalcite and derived composite metal oxide were weighed separately and added to 100 mL of sodium chloride solution with a chloride ion concentration of 50 mg / L. Dilute HNO3 was added to adjust the pH of the solution to 5. The reaction was carried out in a water bath at 25°C under N2 protection with stirring for 4 h. After the reaction, the solution was filtered. The solution potential of the supernatant was measured using a PCl-1 chloride ion selective electrode and a 217 reference electrode. The chloride ion concentration of the solution was calculated based on the standard curve. The chloride ion concentration of the shaped hydrotalcite was then calculated.- The absorption rate was 36 mg / g. Further application in the desalination process for cultural relic preservation showed no significant powdering or dissolution during the reaction. Example 5

[0041] Step A. Using an atom-economical clean process, weigh 200 g Al(OH)3, 122.1 g MgCl2, and 224.3 g Mg(OH)2 according to Mg / Al = 2 / 1. Dissolve them in deionized water to a solid content of 6 wt%, ultrasonically mix thoroughly, and then... o The reaction was carried out under stirring conditions for 2 hours. After the reaction was completed, the slurry was centrifuged and filtered to obtain Mg2Al-CO3. 2- -LDHs hydrotalcite precursors.

[0042] Step B. Take the 64.70g Mg2Al-CO3 obtained in Step A. 2- -LDHs powder and polyvinylpyrrolidone polymeric stabilizer were ultrasonically dispersed in water, then 15.00 g of fast-release powder, 0.60 g of guar gum powder, nitric acid and 3.66 g of boehmite were added and stirred evenly to obtain a mixture, which was then mechanically kneaded; the water-to-powder ratio in the mixture was 0.5, the mass concentration of nitric acid was 6.7%, and the mass concentration of polyvinylpyrrolidone polymeric stabilizer was 0.045%.

[0043] Step C. After forming using an extruder, the pellets are cut into strips and the formed samples are granulated at 1... o The temperature was increased to 80℃ at a rate of C / min and dried for 12 h to obtain strip-shaped, high-purity, and high-strength shaped hydrotalcite Mg2Al-CO3. 2- -LDHs-N, crushing strength of 51 N / particle, specific surface area of ​​100 μm. 2 / g.

[0044] 1 g of shaped hydrotalcite was weighed and loaded into a fixed-bed reactor. The reactor was then introduced with reactants of 0.2% SO2 / 78.8% N2 / 21% O2. SO2 adsorption was tested at 400 °C. The reactor outlet gas was analyzed using a KANE905 flue gas analyzer, and the sulfur capacity of the shaped hydrotalcite reached 20 mg / g. Further application in flue gas desulfurization showed no significant powder shedding or leaching during use. Example 6

[0045] Step A. Using an atom-economical clean process, weigh 200 g Al(OH)3, 122.1 g MgCl2, and 224.3 g Mg(OH)2 according to Mg / Al = 2 / 1. Dissolve them in deionized water with a solid content of 6 wt%, ultrasonically mix thoroughly, and then... oThe reaction was carried out under stirring conditions for 2 hours. After the reaction was completed, the slurry was centrifuged and filtered to obtain Mg2Al-CO3. 2- -LDHs hydrotalcite precursors.

[0046] Step B. Take the 64.70g Mg2Al-CO3 obtained in Step A. 2- -LDHs powder and polyvinylpyrrolidone polymeric stabilizer were ultrasonically dispersed in water, then 15.00 g of fast-release powder, 0.60 g of guar gum powder, nitric acid and 3.66 g of boehmite were added and stirred evenly to obtain a mixture, which was then mechanically kneaded; the water-to-powder ratio in the mixture was 0.5, the mass concentration of nitric acid was 6.7%, and the mass concentration of polyvinylpyrrolidone polymeric stabilizer was 0.045%.

[0047] Step C. After forming using an extruder, the pellets are cut into strips and the formed samples are granulated at 1... o The temperature was increased to 80℃ at a rate of C / min and dried for 12 h to obtain strip-shaped, high-purity, and high-strength shaped hydrotalcite Mg2Al-CO3. 2- -LDHs-N. Further, it is set to 1 o Heating rate increased to 450 °C / min o C. Calcination under CO2 atmosphere for 10 h yielded the shaped derivative composite metal oxide Mg2Al-LDO, with a crushing strength of 51 N / particle and a specific surface area of ​​60 μm. 2 / g.

[0048] The obtained shaped derivative composite metal oxide was used as a carrier to load the PdAg active component, exhibiting excellent metal dispersion, exceeding 40%. Then, 0.1 g was loaded into a fixed-bed reactor, and reactants of 0.66-2.64% H2 / 0.33% C2H2 / 32.80% C2H4 were introduced. Testing was conducted within the range of 30-70 °C, and the reactor outlet gas was detected by gas chromatography. o At reaction temperature C, the conversion rate was 100% and the selectivity was 85%. The molded derivative composite metal oxide showed excellent performance in the selective hydrogenation reaction of alkynes, with no obvious powder shedding during use. Comparative Example 1

[0049] Step A. Using an atom-economical clean process, weigh 200.0 g Al(OH)3, 142.3 g CaCl2, and 215.4 g CaO according to Ca / Al = 2 / 1. Dissolve them in deionized water with a solid content of 6 wt%, ultrasonically mix thoroughly, and then... o The reaction was carried out under stirring conditions for 2 hours. After the reaction was completed, the slurry was centrifuged and filtered to obtain Ca2Al-Cl. - -LDHs hydrotalcite precursors.

[0050] Step B. Take 129.40 g of Ca2Al-Cl obtained in Step A. - -LDHs powder was ultrasonically dispersed in water, then 15.00 g of fast-release powder, 0.60 g of guar gum powder, nitric acid, and 3.66 g of pseudoboehmite were added and stirred until homogeneous to obtain a mixture, which was then mechanically kneaded; the water-to-powder ratio in the mixture was 0.5, the mass concentration of nitric acid was 6.7%, and the mass concentration of polyvinylpyrrolidone polymer stabilizer was 0.045%.

[0051] Step C. After molding using an extruder, the sample is cut into strips and granules. The shaped sample is then dried at 80℃ for 12 h to obtain strip-shaped, high-purity shaped hydrotalcite Ca2Al-Cl. - -LDHs-N, crushing strength is 22 N / particle.

[0052] When placed in an aqueous solution and CO2 is introduced for 5 minutes, the solution turns milky white, the surface structure is unstable, and obvious powder shedding and dissolution occur. Comparative Example 2

[0053] Step A. Mix Mg(NO3)2 and Al(NO3)3 according to Mg 2+ / Al 3+ A mixed salt solution is prepared with a molar ratio of 2, wherein [Mg] 2+ =1.2 mol / L; according to n(urea) / [n(Mg) 2+ )+n(Al 3+ Prepare equal volumes of alkaline solution in a ratio of 3.3. After mixing, transfer the solutions to a high-pressure reactor and react at 150°C for 48 h. After the reaction is complete, remove the reactor and allow it to cool naturally to room temperature. Wash with deionized water by centrifugation until the supernatant is neutral to obtain Mg2Al-CO3. 2- -LDHs.

[0054] Step B. Take 60g of Mg2Al-CO3 obtained in Step A. 2- -LDHs powder and polyvinylpyrrolidone polymeric stabilizer were ultrasonically dispersed in water, then 15.00 g of fast-release powder, 0.60 g of guar gum powder, nitric acid and 3.66 g of boehmite were added and stirred evenly to obtain a mixture, which was then mechanically kneaded; the water-to-powder ratio in the mixture was 0.5, the mass concentration of nitric acid was 6.7%, and the mass concentration of polyvinylpyrrolidone polymeric stabilizer was 0.045%.

[0055] Step C. After forming using an extruder, the pellets are cut into strips, and the formed samples are granulated at 1... o The temperature was increased to 80℃ at a rate of C / min and dried for 12 h to obtain shaped hydrotalcite Mg2Al-CO3.2- -LDHs.

[0056] The hydrotalcite prepared by the above-mentioned hydrothermal method is prone to producing magnesium carbonate impurities and has low crushing strength (10 N / particle), thus exhibiting poor structural stability.

Claims

1. A method for preparing highly stable molded hydrotalcite, characterized in that, The specific operation of the preparation method is as follows: hydrotalcite powder and polymer stabilizer are ultrasonically dispersed in water, then fast-release powder, guar gum powder, adhesive solvent and kneading paste are added, and the mixture is stirred evenly to obtain a mixture. Then, the mixture is mechanically kneaded, and then shaped by an extruder with perforated plates of different shapes. The mixture is cut into strips and granules, and dried at a heating rate of 1-2 ℃ / min to 60-80 ℃ for 12-24 h to obtain highly stable shaped hydrotalcite of different shapes. The polymeric stabilizer is one or more of polyethylene glycol, polyvinyl alcohol, and polyvinylpyrrolidone; the kneading paste is boehmite or starch; and the adhesive solvent is nitric acid. The water-to-powder ratio of the mixture is 0.33-0.50; the mass concentration of the polymer stabilizer in the mixture is 0.01-0.045%, and the mass concentration of nitric acid is 1-9%. The powder raw materials in the mixture consist of hydrotalcite powder, quick-release powder, guar gum powder and kneading paste. The mass percentage of guar gum powder in the powder raw materials is 0.02-2.5%, the mass percentage of kneading paste is 1.2-14.2%, the mass percentage of quick-release powder is 5-58.3%, and the remainder is hydrotalcite powder.

2. The preparation method according to claim 1, characterized in that, The divalent metal ions in the layers of the hydrotalcite are Mg. 2+ Ca 2+ Zn 2+ One or two of them, with trivalent metal ions being Al 3+ The molar ratio of divalent metal ions to trivalent metal ions is 2-4; the interlayer anion is Cl. - NO3 - or CO3 2- .

3. The preparation method according to claim 1, characterized in that, The preparation method of the hydrotalcite is as follows: a divalent metal compound and an Al source with a molar ratio of 2-4 are weighed and dissolved in deionized water, and ultrasonically mixed evenly, wherein the solid content is 5-30 wt%, and then stirred and reacted at 80-120℃ for 2-6 days. h. After the reaction is complete, the slurry is centrifuged and filtered to obtain hydrotalcite free of other impurities; the Al source is Al(OH)3; the divalent metal compound is a mixture of CaCl2 and CaO with a molar ratio of 1:3-7, a mixture of CaCl2 and Ca(OH)2 with a molar ratio of 1:3-7, a mixture of MgCl2 and Ca(OH)2 with a molar ratio of 1:3-7, a mixture of CaCl2, MgCl2 and Ca(OH)2 with a molar ratio of 1:1:6-10, a mixture of MgCl2 and Mg(OH)2 with a molar ratio of 1:3-5, a mixture of CaCl2, MgCl2, Ca(OH)2 and Mg(OH)2 with a molar ratio of 1-2:1:3-7:2-3, a mixture of ZnCl2, MgCl2 and Zn(OH)2 with a molar ratio of 1:1:6-10, or a mixture of ZnCl2 and Mg(OH)2 with a molar ratio of 1:3-7.

4. A method for preparing a highly stable molded derivative composite metal oxide, characterized in that, The specific operation of the preparation method is as follows: the highly stable shaped hydrotalcite prepared by the method of any one of claims 1-3 is calcined at 450-600 ℃ for 4-10 h in an oxidizing atmosphere.

5. The preparation method according to claim 4, characterized in that, The oxidizing atmosphere is air or oxygen; the heating rate of the calcination is 1-2 °C / min.

6. The highly stable shaped hydrotalcite prepared by the method according to any one of claims 1-3 can be used for adsorbing heavy metal ions in wastewater, desalination in cultural relic protection, flue gas desulfurization, and as a catalyst carrier.

7. The highly stable molded derivative composite metal oxide prepared by the method according to claim 4 can be used for adsorbing heavy metal ions in wastewater, desalination in cultural relic protection, flue gas desulfurization, and as a catalyst support.

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