Preparation method of porous titanium adsorbent

Abstract

The invention discloses a preparation method of a porous titanium lithium adsorbent, which comprises the following steps: preparing a titanium lithium ion sieve precursor, a hydrophilic binder and a pore-foaming agent in proportion, heating and stirring in water to react, and drying and pelletizing after the reaction is finished to obtain the porous titanium lithium adsorbent. Compared with traditional PVC forming, the method has the advantages that the hydrophilic binder, the pore-foaming agent, the curing agent and the water are used for curing forming of the titanium-based lithium adsorbent, preparation of the multi-pore-channel and high-pore-volume titanium-based adsorbent is achieved, use of an organic solvent and a subsequent distillation recovery process are avoided, toxicity in the whole production process is reduced, and the method is suitable for industrial production. The production process of the lithium adsorbent is more environment-friendly, and the method has a great application prospect in the field of lithium extraction by an adsorption method.

Description

Technical Field

[0001] The invention relates to the technical field of lithium ion adsorbents, and in particular to a method for preparing a porous titanium-based adsorbent. Background Art

[0002] Lithium and its salts are widely used in various industries.

[0003] Adsorption is a lithium extraction technology that has great advantages from the perspective of environment and economy. In particular, the advantages of extracting lithium from low-grade high-magnesium lithium brine and seawater are more obvious. At present, adsorbents are mainly divided into four categories: manganese, titanium, aluminum and doped adsorbents.

[0004] However, conventional lithium adsorbent precursors are all in powder form with poor fluidity and permeability. The dissolution rate is high during the adsorption and elution process, and it will cause the loss of the adsorbent, which is not easy to operate industrially. In addition, conventional molding methods often use organic solvents, which are inevitably inhaled during the production operation, causing harm to human health. In addition, due to process limitations, a large amount of wastewater will be generated, and it contains a large amount of organic solvents that need to be distilled and recovered before discharge. The process is complicated. Therefore, how to improve the utilization efficiency of titanium-based lithium adsorbents and avoid the use of organic solvents is a technical problem that needs to be solved at present. Summary of the invention

[0005] The problem to be solved by the present invention is to propose an innovative solution to the shortcomings of the above-mentioned prior art and provide a method for preparing a porous titanium-based lithium adsorbent, thereby realizing the preparation of a multi-porous, high pore volume titanium-based adsorbent, avoiding the use of organic solvents and subsequent distillation recovery processes, reducing the toxicity of the entire production process, making the production process of the lithium adsorbent more green and environmentally friendly, and having great application prospects in the field of lithium extraction by adsorption.

[0006] To solve the above problems, the present invention adopts the following solution: A method for preparing a porous titanium-based adsorbent, characterized in that it comprises the following steps: S1: Prepare titanium-based lithium adsorbent precursor, hydrophilic binder, and porogen in a weight ratio of 1000: (150-250): (4-6) S2: adding the prepared titanium-based lithium adsorbent precursor, hydrophilic binder and porogen into water and stirring to mix, wherein the weight ratio of the total weight of the titanium-based lithium adsorbent precursor and the hydrophilic binder to water is 1:1.5-2; S3: Stirring the reaction at 55-75°C for 2-3h, after the hydrophilic binder in the raw material mixture is solidified, drying and pelletizing to obtain a porous titanium-based adsorbent with an average pore diameter of 4-12nm and a pore volume of 1-3ml / g.

[0007] Furthermore, the method for preparing the porous titanium-based adsorbent is characterized in that the hydrophilic binder is one or more of dextran, phenolic resin, polyvinyl alcohol, and polyacrylate.

[0008] Furthermore, the method for preparing the porous titanium-based adsorbent is characterized in that the titanium-based lithium adsorbent precursor is Li2TiO3.

[0009] Furthermore, the preparation method of the porous titanium-based adsorbent is characterized in that the porogen is an organic porogen selected from one or more of polyvinyl pyrrolidone, polyethylene glycol, Tween emulsifiers, and Span emulsifiers, wherein the polyvinyl pyrrolidone is PVP k30 and the polyethylene glycol is PEG400.

[0010] Furthermore, the method for preparing the porous titanium-based adsorbent is characterized in that the particle size of the porous titanium-based lithium adsorbent is 0.5-1 mm.

[0011] Furthermore, the preparation method of the porous titanium-based adsorbent is characterized in that, after the hydrophilic binder in the raw material mixture is solidified in S3, a curing agent is added and heated and stirred to react; the curing agent is one or more of sodium hydroxide, potassium persulfate, azobisisobutyl cyanide, ammonium persulfate, hydrochloric acid, sulfuric acid, and epichlorohydrin, wherein the weight ratio of the hydrophilic binder to the curing agent is 100:10-50.

[0012] Preferably, the weight ratio of the hydrophilic binder to the curing agent is 100:30-40 Furthermore, the method for preparing the porous titanium-based adsorbent is characterized in that the porous titanium-based adsorbent obtained in S3 is dried and dehydrated at 80-120° C. for 10-15 hours.

[0013] The technical effects of the present invention are as follows: a hydrophilic binder, a porogen, a curing agent, and water are used to solidify and mold a titanium-based lithium adsorbent, thereby realizing the preparation of a multi-porous, high-pore-volume titanium-based adsorbent, avoiding the use of organic solvents, reducing the toxicity of the entire production process, and making the titanium-based adsorbent molding process more green and environmentally friendly. The use of a drying process avoids the generation of a large amount of wastewater and eliminates the distillation recovery process, thereby reducing the complexity of the molding process. Experimental verification shows that the use of a hydrophilic binder in this design is mainly to avoid the use of organic solvents. Compared with the traditional PVC phase inversion molding method, it avoids the use of organic solvents and the subsequent distillation recovery process, reduces the toxicity of the entire production process, and makes the production process of the lithium adsorbent more green and environmentally friendly.

[0014] The adsorbent pore size of the adsorbent of the present invention has an average pore size of 4-12nm and a pore volume of 1-3ml / g. Compared with other organic molding methods, the present invention uses a hydrophilic binder as a main skeleton, combines a porogen to form pores, and finally uses a curing agent to further reinforce the particle strength. The pore size and pore volume of the prepared adsorbent are larger than those of the PVC phase conversion method using an organic solvent, which is convenient for ion exchange and greatly improves the adsorption and desorption efficiency during the adsorption process. Compared with other adsorbents formed by phase separation methods, the present invention avoids the use of organic solvents during the molding process, reduces the toxicity of the entire production process, makes the entire process more green and environmentally friendly, avoids the generation of a large amount of waste water, and also avoids the subsequent distillation process. The production process is simpler and easier to operate. DETAILED DESCRIPTION Example

[0015] Take 200 kg of titanium-based lithium adsorbent precursor Li2TiO3 (purchased from Yunnan Gangfeng New Materials Co., Ltd.), 40 kg of phenolic resin, 20 kg of polyethylene glycol, and 480 kg of water and add them into the reactor, heat to 60 ° C and stir for 2.5 hours; after stirring, move the slurry to a double cone dryer and add 16 kg of potassium persulfate to mix evenly, heat to 70 ° C and react at normal pressure for 1 hour, then use a roller pelletizer to cut the material into particles of about 1 mm, and finally put the cut particles into an oven and keep the temperature at 120 ° C for 10 hours to obtain the finished product. Example

[0016] Take 200 kg of titanium-based lithium adsorbent precursor Li2TiO3 (purchased from Yunnan Gangfeng New Materials Co., Ltd.), 40 kg of polyacrylate, 20 kg of PVPk30, and 480 kg of water and add them into the reactor, heat to 65 ° C and stir for 3 hours; after stirring, move the slurry to a double cone dryer and add 16 kg of potassium persulfate, stir and mix evenly, heat to 65 ° C and react at normal pressure for 1.5 hours, then use a roller pelletizer to cut the material into particles of about 1.5 mm, and finally put the cut particles into an oven at a constant temperature of 100 ° C for 15 hours to obtain the finished product. Example

[0017] Take 150kg of titanium-based lithium adsorbent precursor Li2TiO3 (purchased from Yunnan Gangfeng New Materials Co., Ltd.), 30kg of polyacrylate, 15kg of PVPk30, and 360kg of water and add them into the reactor, heat it to 65°C and stir for 3h; after stirring, move the slurry to a double cone dryer and add 12kg of potassium persulfate, stir and mix evenly, heat it to 75°C and react at normal pressure for 1h, then use a roller pelletizer to cut the material into particles of about 1mm, and finally put the cut particles into an oven at a constant temperature of 120°C for 10h to obtain the finished product. Example

[0018] Take 300 kg of titanium-based lithium adsorbent precursor Li2TiO3 (purchased from Yunnan Gangfeng New Materials Co., Ltd.), 60 kg of polyacrylate, 35 kg of PEG400, and 540 kg of water and add them into the reactor, heat it to 70 °C and stir for 2 hours; after stirring, move the slurry to a double cone dryer and add 24 kg of azobisisobutyl cyanide, stir and mix evenly, heat it to 70 °C and react at normal pressure for 1 hour, then use a stick pelletizer to cut the material into particles of about 1 mm, and finally put the cut particles into an oven and keep it at a constant temperature of 120 °C for 10 hours to obtain the finished product. Example

[0019] Take 300 kg of titanium-based lithium adsorbent precursor Li2TiO3 (purchased from Yunnan Gangfeng New Materials Co., Ltd.), 60 kg of polyvinyl alcohol, 35 kg of Tween 60, and 540 kg of water and add them into the reactor, heat it to 65 ° C and stir for 3 hours; after stirring, move the slurry to a double cone dryer and add 24 kg of azobisisobutyl cyanide, stir and mix evenly, heat it to 70 ° C and react at normal pressure for 1 hour, then use a stick pelletizer to cut the material into particles of about 1 mm, and finally put the cut particles into an oven and keep it at a constant temperature of 120 ° C for 10 hours to obtain the finished product.

[0020] Comparative Example 1 Take 300 kg of titanium-based lithium adsorbent precursor Li2TiO3 (purchased from Yunnan Gangfeng New Materials Co., Ltd.), 60 kg of polyvinyl alcohol, and 540 kg of water and add them into the reactor, heat to 65 ° C and stir for 3 hours; after stirring, move the slurry to a double cone dryer and add 24 kg of azobisisobutyl cyanide, stir and mix evenly, heat to 70 ° C and react at normal pressure for 1 hour, then use a roller pelletizer to cut the material into particles of about 1 mm, and finally put the cut particles into an oven and keep the temperature at 120 ° C for 10 hours to obtain the finished product.

[0021] Comparative Example 2 Take 300 kg of titanium-based lithium adsorbent precursor (purchased from Yunnan Gangfeng New Materials Co., Ltd.), 60 kg of polyvinyl chloride, and 540 kg of water and add them into the reactor, heat to 70°C and stir for 2 hours; after stirring, move the slurry to a double cone dryer and add 24 kg of azobisisobutyl cyanide, stir and mix evenly, heat to 70°C and react at normal pressure for 1 hour. After discharging, it was found that it could not be formed and was a powder mixture.

[0022] Comparative Example 3 Take 200kg of titanium-based lithium adsorbent precursor (purchased from Yunnan Gangfeng New Materials Co., Ltd.), 35kg of Tween 60, and 480kg of water and add them into the reactor, heat to 65°C and stir for 3h; after stirring, move the slurry to a double cone dryer and add 16kg of potassium persulfate, stir and mix evenly, heat to 65°C and react at normal pressure for 1.5h, then use a roller pelletizer to cut the material into particles of about 1.5mm, and finally put the cut particles into an oven at a constant temperature of 100°C for 15h. After discharging, it was found that it could not be formed and was a powder mixture.

[0023] Comparative Example 4 This example is an example of using organic solvent molding (patent number 202310446839.7, entitled A method and application for preparing lithium ion sieve adsorbent particles). 3g of polyvinylidene fluoride, 0.1g of potassium chloride porogen and 30mL of N,N-dimethylformamide are mechanically stirred at 60°C for 24h, and then 6g of Li2TiO3 (purchased from Yunnan Gangfeng New Materials Co., Ltd.) is added for ultrasonic dispersion to obtain a first mixed solution; the first mixed solution obtained above is subjected to phase inversion treatment, specifically, the first mixed solution is dripped into deionized water using a syringe to form particles; the particles are washed 3 times with deionized water and then placed in a vacuum drying oven, and dried at 50°C for 24h to obtain a precursor material.

[0024] The pore size data detected by JW-BK300 specific surface area and pore size analyzer are as follows: The samples of the above-mentioned implementation cases were activated (an appropriate amount of sample was poured into 0.2M hydrochloric acid for 24 hours of activation, and then taken out and dried). All the activated samples of the embodiments and comparative examples were placed in salt lake brine for adsorption experiments under the same conditions. The test results are as follows (Comparative Examples 2 and 3 were solid powders, and the components were lost during the test, so accurate measurement data could not be obtained): sample Li adsorption capacity (g / L) Li resolution (%) Dissolution loss after 10 cycles (%) Example 1 10.53 97.32 0.21 Example 2 9.35 98.21 0.11 Example 3 11.21 97.34 0.21 Example 4 10.34 98.12 0.12 Example 5 10.78 98.56 0.20 Comparative Example 1 3.21 75.23 0.12 Comparative Example 2 - - - Comparative Example 3 - - - Comparative Example 4 9.23 94.23 2.15 The above experimental results show that the adsorbent of the present invention has the characteristics of large pore size, high pore volume, high adsorption capacity and high resolution. Compared with the method of forming using organic solvents, the performance difference is small. The method of synthesizing the adsorbent can effectively avoid the use of organic solvents, making the production process of lithium adsorbent more green and environmentally friendly, and has great application prospects in the field of lithium extraction by adsorption.

[0025] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A method for preparing a porous titanium-based adsorbent, characterized in that: The steps include: S1: Prepare titanium-based lithium adsorbent precursor, hydrophilic binder, and porogen in a weight ratio of 1000: (150-250): (4-6) S2: adding the prepared titanium-based lithium adsorbent precursor, hydrophilic binder and porogen into water and stirring to mix, wherein the weight ratio of the total weight of the titanium-based lithium adsorbent precursor and the hydrophilic binder to water is 1:1.5-2; S3: stirring the reaction at 55-70°C for 2-3h, and after the hydrophilic binder in the raw material mixture is solidified, the mixture is dried and pelletized to obtain a porous titanium adsorbent having an average pore diameter of 4-12nm and a pore volume of 1-3ml / g; Wherein, the hydrophilic binder is one or more of dextran, phenolic resin, polyvinyl alcohol and polyacrylate.

2. The method for preparing the porous titanium-based adsorbent according to claim 1, characterized in that: The titanium-based lithium adsorbent precursor is Li2TiO3.

3. The method for preparing the porous titanium-based adsorbent according to claim 1, characterized in that: The porogen is an organic porogen, selected from one or more of polyvinyl pyrrolidone, polyethylene glycol, Tween emulsifiers, and Span emulsifiers, wherein the polyvinyl pyrrolidone is PVP k30 and the polyethylene glycol is PEG400.

4. The method for preparing the porous titanium-based adsorbent according to claim 1, characterized in that: The particle size of the porous titanium-based lithium adsorbent is 0.5-1 mm.

5. The method for preparing the porous titanium-based adsorbent according to claim 1, characterized in that: In S3, after the hydrophilic binder in the raw material mixture is cured, a curing agent is added and heated and stirred for reaction; the curing agent is one or more of sodium hydroxide, potassium persulfate, azobisisobutyl cyanide, ammonium persulfate, hydrochloric acid, sulfuric acid, and epichlorohydrin, wherein the weight ratio of the hydrophilic binder to the curing agent is 100:10-50.

6. The method for preparing the porous titanium-based adsorbent according to claim 1, characterized in that: The porous titanium-based adsorbent obtained from S3 is dried and dehydrated at 80-120°C for 10-15h.