Preparation method of manganese oxide lithium ion sieve lithium adsorption material

Abstract

The invention provides a manganese oxide lithium ion sieve lithium adsorption material. The material is a manganese oxide lithium ion sieve with a porous structure and a molecular formula of MnO2.0. 5H2O. The invention also provides a preparation method of the manganese oxide lithium ion sieve lithium adsorption material. The preparation method comprises the following steps: preparing a Mn (OH) 2 suspension by using MnCl2 and ammonia water, then fixing a dispersion medium in a membrane dispersion microflow reactor, introducing gas CO2 for reaction, and obtaining manganese carbonate microspheres after the reaction is finished; and putting the calcined manganese carbonate microspheres and LiOH.H2O into a high-pressure kettle for hydrothermal reaction, and sequentially calcining, pickling, filtering, washing and drying the reaction product to obtain the manganese oxide lithium ion sieve. The manganese oxide lithium ion sieve provided by the invention has the advantages of high adsorption capacity, good cycle stability, high lithium selectivity and the like, and the technological process is green and pollution-free.

Description

Technical Field

[0001] The present invention belongs to the technical field of adsorption materials, and particularly relates to a preparation method of a manganese oxide lithium ion sieve for adsorbing lithium materials. Background Technique

[0002] Lithium and its compounds are widely used in fields such as space technology, oil exploration, emerging metal materials, biomedicine, and nuclear fusion power generation, and are indispensable strategic resources in the national economy and national defense construction. At present, the methods for extracting lithium from wastewater include extraction method, membrane separation method, electrochemical method, precipitation method, and adsorption method. The adsorption method has the advantages of being easy to realize industrial application, having no requirement for the lithium-magnesium ratio of wastewater, high selectivity, simple process, and environmental friendliness. The adsorbent is the key to the adsorption method. Lithium adsorbents include organic adsorbents such as ion exchange resins and ion imprinted polymers, and inorganic adsorbents such as aluminum salts, titanium-based ion sieves, and manganese-based lithium ion sieves. Manganese-based lithium ion sieves are mainly prepared by introducing Li + into manganese oxide, and acid treatment is used to displace Li + in it to obtain an adsorbent with hole size and special properties. Manganese-based lithium ion sieves have a high theoretical adsorption capacity, strong stability, and high lithium selective adsorption, but there are problems such as low adsorption capacity, high manganese dissolution loss rate, and a sharp decrease in adsorption capacity after repeated use.

[0003] Chinese Patent Application (Publication No.: 117566804A) discloses a preparation method of a porous spherical manganese-based lithium ion sieve. The method is simple and easy to operate, reduces the process difficulty, and the adsorption capacity is 58.79 mg / g. Chinese Patent Application (Publication No.: CN109078601A) discloses a preparation method of a nano-tubular manganese oxide lithium ion sieve. This special-shaped lithium ion sieve adsorbent has a large adsorption capacity and a fast adsorption rate for lithium ions, and the adsorption capacity is 14.0 - 37.0 mg / g. In summary, there are problems such as uneven particles, high adsorption amount, and high manganese dissolution loss rate in the existing preparation methods of manganese-based lithium ion sieve adsorption materials. Therefore, it is urgent to develop a new preparation technology for manganese-based lithium ion sieve adsorption materials.

[0004] Microfluidic technology can be used to prepare nanomaterials, which can precisely manipulate trace fluids in channels at the microscale to achieve the controllable preparation of nanomaterials. Compared with the traditional kettle method, microfluidic technology can effectively define the nucleation and growth stages of nanoparticles, achieve precise control of particle size, size distribution, and morphology, and improve repeatability. The present invention uses microfluidic technology to control the flow rate and flow of the reaction solution, introduces the reaction solution into the mixing channel, realizes the full mixing of the manganese source and the carbonate source, and realizes the preparation of nanoscale manganese carbonate particles; this technology has the advantages of fast and uniform mixing speed, controllable particle size and shape, low operating energy consumption, small material stagnation, and high stability. At the same time, the manganese oxide lithium ion sieve prepared from nanoscale manganese carbonate and lithium salt has a high adsorption capacity, low manganese dissolution rate, and good cycle stability performance. Summary of the Invention

[0005] In view of the deficiencies of the existing technology, the present invention provides a method for preparing a manganese oxide lithium ion sieve to solve the problems of low lithium adsorption capacity, poor recycling performance, and high manganese dissolution rate of existing manganese-based ion sieves.

[0006] To achieve the above object, the present invention provides a method for preparing a manganese oxide lithium ion sieve adsorbing lithium material, and the material is a manganese oxide lithium ion sieve with a porous structure and a molecular formula of MnO 2 ·0.5H 2 O.

[0007] The present invention also provides the method for preparing the manganese oxide lithium ion sieve adsorbing lithium material as described above, and the specific steps include:

[0008] First, prepare a Mn(OH) 2 suspension using MnCl 2 , ammonia water, and ethylene glycol. Then, fix the dispersion medium in a membrane dispersion microfluidic reactor, introduce gas CO 2 for reaction. After the reaction, obtain manganese carbonate microspheres;

[0009] Second, calcine the manganese carbonate to obtain Mn 2 O 3 , and place LiOH·H 2 O in an autoclave for hydrothermal reaction to obtain a solid first intermediate product;

[0010] Calcine the first intermediate product to obtain a second intermediate product;

[0011] Treat the second intermediate product with acid to obtain a third intermediate product;

[0012] Filter, wash, and dry the third intermediate product to obtain the manganese oxide lithium ion sieve with a porous structure.

[0013] Preferably, the membrane dispersion microfluidic reactor for preparing manganese carbonate microspheres comprises seven parts, Mn(OH) 2 suspension inlet 1, gas inlet 2, reactor upper cover 3, dispersion medium 4, reaction chamber 5, reaction product outlet 6, and reactor lower liner 7.

[0014] The dispersion medium 4 is fixed in the membrane dispersion microfluidic reactor, and the Mn(OH) 2 suspension in the container enters the upper side of the dispersion medium 4 in the reactor under the action of a pump, and the Mn(OH) 2 suspension flows on the upper side of the membrane; CO 2 gas passes through the dispersion medium 4 under pressure, forming small bubbles on the lower side of the dispersion medium 4, and the continuously flowing Mn(OH) 2 suspension takes the bubbles away from the lower surface of the dispersion medium 4, and the bubbles and the suspension are efficiently mixed and flow out of the reactor 3.

[0015] Preferably, the molar ratio of ammonia water to MnCl 2 for preparing manganese carbonate microspheres is 2:1 to 5:1, the molar ratio of ethylene glycol to MnCl 2 is 5:1 to 20:1, the carbon dioxide flow rate is 0.5 to 10 L / min, the reaction time is 5 to 50 s, the reaction temperature is 40 to 80 °C, the pore diameter of the membrane is 2 to 10 μm, and the pipe diameter size is 1.0*3 mm to 1.5*3 mm.

[0016] Preferably, the temperature for the calcination treatment of manganese carbonate is 500 to 900 °C, and the reaction time is 2 to 8 h.

[0017] Preferably, the lithium-to-manganese ratio of LiOH·H 2 O to Mn 2 O 3 in the hydrothermal reaction is 1.0 to 1.3, the temperature is 80 to 160 °C, and the reaction time is 6 to 48 h.

[0018] Preferably, the temperature for the calcination treatment of the first intermediate product is 300 to 500 °C, and the reaction time is 2 to 6 h.

[0019] Preferably, the concentration of dilute hydrochloric acid for the acid treatment is 0.5 to 1.0 mol / L, the temperature is 20 to 50 °C, and the reaction time is 6 to 48 h.

[0020] Preferably, the washing treatment is to wash the third intermediate product with deionized water multiple times until the pH of the filtrate is 6 to 8.

[0021] Preferably, the drying treatment is carried out at a temperature of 60 to 80 °C.

[0022] Compared with the prior art, the beneficial effects of the present invention include:

[0023] (1) The present invention uses microfluidic technology to prepare manganese carbonate microspheres. This method has the advantages of fast and uniform mixing speed, controllable particle size and shape, high CO 2 utilization rate, low operation energy consumption, small material stagnation, and high stability. The prepared nano-MnCO 3 has a particle size of 10 - 50 nm, and multiple high-throughput MnCO 3 microspheres can be prepared simultaneously, improving the preparation efficiency.

[0024] (2) The lithium-ion sieve adsorbent material of manganese oxide prepared by the two-stage high-temperature solid-phase method in the present invention has the advantages of porous structure, high dispersibility, high adsorption capacity, good cycle stability, high lithium selectivity, and low manganese dissolution rate. Description of the Drawings

[0025] Through the following description in combination with the drawings, the above and other aspects, features, and advantages of the embodiments of the present invention will become clearer. In the drawings:

[0026] Figure 1 is the process flow chart of the preparation method of the lithium-ion sieve of manganese oxide in the embodiment of the present invention;

[0027] Figure 2 is the schematic diagram (enlarged) of the membrane dispersion microfluidic reactor structure of the manganese carbonate microspheres in the embodiment of the present invention. Among them, 1 is the inlet of the Mn(OH) 2 suspension, 2 is the gas inlet, 3 is the reactor upper cover, 4 is the dispersion medium, 5 is the reaction chamber, 6 is the reaction product outlet, and 7 is the reactor lower liner.

[0028] Figure 3 is the SEM image of the lithium-ion sieve of manganese oxide in Example 1 of the present invention.

[0029] Figure 4 is the XRD pattern of the lithium-ion sieve of manganese oxide in Example 1 of the present invention. Detailed Embodiments

[0030] Hereinafter, the specific embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention can be implemented in many different forms, and the present invention should not be construed as being limited to the specific embodiments set forth herein. On the contrary, these embodiments are provided to explain the principles of the present invention, so that those skilled in the art can understand various modifications of the various embodiments of the present invention.

[0031] The embodiment of the present invention provides a preparation method of a lithium-ion sieve adsorbent material of manganese oxide. The material is a manganese oxide lithium-ion sieve with a porous structure and a molecular formula of MnO 2 ·0.5H 2 O.

[0032] The embodiment of the present invention provides the preparation method of the lithium - adsorbing material of manganese oxide lithium ion sieve as described above. Refer to Figure 1 , the preparation method includes the following steps:

[0033] Step S10: Prepare a Mn(OH) 2 suspension with MnCl 2 , ammonia water and ethylene glycol. Then fix the dispersion medium in the membrane - dispersion micro - flow reactor, introduce gas CO 2 for reaction. After the reaction ends, obtain manganese carbonate microspheres;

[0034] Step S20: Calcinate the manganese carbonate to obtain Mn 2 O 3 , and place LiOH·H 2 O in an autoclave for hydrothermal reaction to obtain a solid first intermediate product;

[0035] Step S30: Calcinate the first intermediate product to obtain a second intermediate product;

[0036] Step S40: Acid - treat the second intermediate product to obtain a third intermediate product;

[0037] Step S50: Filter, wash and dry the third intermediate product to obtain the manganese oxide lithium ion sieve with a porous structure.

[0038] Specifically, the membrane - dispersion micro - flow reactor for preparing manganese carbonate microspheres includes 7 parts: Mn(OH) 2 suspension inlet 1, gas inlet 2, reactor upper cover 3, dispersion medium 4, reaction chamber 5, reaction product outlet 6, reactor lower liner 7.

[0039] The dispersion medium 4 is fixed in the membrane - dispersion micro - flow reactor. The Mn(OH) 2 suspension in the container enters the upper side of the dispersion medium 4 in the reactor under the action of a pump, and the Mn(OH) 2 suspension flows on the upper side of the membrane; the CO 2 gas passes through the dispersion medium 4 under pressure and forms small bubbles on the lower side of the dispersion medium 4. The continuously flowing Mn(OH) 2 suspension takes the bubbles away from the lower surface of the dispersion medium 4, and the bubbles and the suspension are efficiently mixed and flow out of the reactor 3.

[0040] Specifically, the molar ratio of ammonia water to MnCl 2 for preparing manganese carbonate microspheres is 2:1 - 5:1, and the molar ratio of ethylene glycol to MnCl 2 is 5:1 - 20:1, and the CO 2The flow rate is 0.5 - 10 L / min, the reaction time is 5 - 50 s, the reaction temperature is 40 - 80 °C, the pore size of the membrane is 2 - 10 μm, and the pipe diameter is 1.0 * 3 mm - 1.5 * 3 mm.

[0041] Specifically, the temperature for the calcination treatment of manganese carbonate is 800 °C, and the reaction time is 5 h.

[0042] Specifically, for the hydrothermal reaction, the lithium-manganese ratio of LiOH·H 2 O to Mn 2 O 3 is 1.1, the temperature is 120 °C, and the reaction time is 48 h.

[0043] Specifically, the temperature for the calcination treatment of the first intermediate product is 400 °C, and the reaction time is 4 h.

[0044] Specifically, the concentration of dilute hydrochloric acid for the acid treatment is 0.5 mol / L, the temperature is 25 °C, and the reaction time is 24 h.

[0045] Specifically, for the washing treatment, deionized water is used to wash the third intermediate product multiple times until the pH of the filtrate is 6 - 8.

[0046] Specifically, the drying treatment is carried out at a temperature of 60 °C.

[0047] Example 1

[0048] (1) Put 6 g of MnCl 2 ·4H 2 O and 12 mL of NH 3 ·H 2 O into a flask, add 140 mL of EG (ethylene glycol) to the flask to prepare a Mn(OH) 2 suspension. Then, fix the dispersion medium in a dispersed microfluidic reactor with a membrane pore size of 5 μm and a pipe diameter of 1.5 * 3 mm, introduce CO 2 gas at a rate of 1 L / min, and react at 60 °C for 10 s to obtain manganese carbonate microspheres;

[0049] (2) Calcinate the obtained manganese carbonate at 500 °C for 5 h to obtain Mn 2 O 3 ,Mn 2 O 3 and LiOH·H 2 O carry out a hydrothermal reaction with a lithium-manganese ratio of 1.1, at a temperature of 120 °C and a reaction time of 48 h. After the reaction is completed, a solid first intermediate product is obtained;

[0050] (3) Calcinate the obtained first intermediate product at 400 °C for 4 h to obtain a second intermediate product;

[0051] (4) Pickle the obtained second intermediate product with 0.5 mol / L dilute hydrochloric acid for 24 h at a reaction temperature of 25 °C to obtain the third intermediate product;

[0052] (5) Filter the obtained third intermediate product, wash it with deionized water until the pH of the filtrate is 7, and dry it at 60 °C to obtain the manganese oxide lithium ion sieve with a porous structure.

[0053] The SEM scanning image of the lithium material product adsorbed by the manganese oxide lithium ion sieve is shown in Figure 3 , and the XRD diffraction pattern of the porous manganese oxide lithium ion sieve adsorbed lithium material product is shown in Figure 4 . By comparing the XRD diffraction analysis results with the diffraction pattern, it can be found that the positions of each peak coincide, and there are no other impurity peaks, indicating that the product obtained by this preparation method has a high purity.

[0054] In this example, the lithium adsorption capacity of the obtained manganese oxide lithium ion sieve product is 77.66 mg / g, and the manganese dissolution rate is 1.07%. In the 5-cycle experiment of lithium ion adsorption / desorption, the lithium adsorption capacity is stable above 68.29 mg / g, and the manganese dissolution rate is lower than 1.12%. It shows good cycle stability and solves the problems of poor cycle adsorption / desorption performance and serious manganese dissolution of the manganese oxide ion sieve.

[0055] Example 2

[0056] (1) Put 7 g of MnCl 2 ·4H 2 O and 15 mL of NH 3 ·H 2 O into a flask, add 120 mL of EG (ethylene glycol) to the flask to prepare a Mn(OH) 2 suspension. Then, fix the dispersion medium in a dispersion microfluidic reactor with a membrane pore size of 5 μm and a tube diameter of 1.5 * 3 mm, and introduce CO 2 gas at a rate of 2 L / min and react at 60 °C for 15 s to obtain manganese carbonate microspheres;

[0057] (2) Calcinate the obtained manganese carbonate at 500 °C for 4 h to obtain Mn 2 O 3 , Mn 2 O 3 and LiOH·H 2 O carry out a hydrothermal reaction at a lithium-manganese ratio of 1.1, a temperature of 120 °C, and a reaction time of 48 h. After the reaction is completed, a solid first intermediate product is obtained;

[0058] (3) Calcinate the obtained first intermediate product at 400 °C for 4 h to obtain the second intermediate product;

[0059] (4) The obtained second intermediate product is pickled with 0.5 mol / L dilute hydrochloric acid for 24 h at a reaction temperature of 25 °C to obtain a third intermediate product;

[0060] (5) The obtained third intermediate product is filtered, washed with deionized water until the pH of the filtrate is 7, and dried at 60 °C to obtain the manganese oxide lithium ion sieve with a porous structure.

[0061] In this example, the lithium ion adsorption capacity of the obtained product was tested. The test method and process were the same as those in Example 1. The test results showed that the lithium adsorption capacity of this product was 64.23 mg / g, the manganese dissolution rate was 1.79%, and in 5 cycles of lithium ion adsorption / desorption experiments, the lithium adsorption capacity was stable above 55.29 mg / g, and the manganese dissolution rate was lower than 1.74%.

[0062] Example 3

[0063] (1) 8 g of MnCl 2 ·4H 2 O and 15 mL of NH 3 ·H 2 O are placed in a flask, and 160 mL of EG (ethylene glycol) is added to the flask to prepare a suspension of Mn(OH) 2 Then, the dispersion medium is fixed in a dispersion microfluidic reactor with a membrane pore size of 5 μm and a tube diameter of 1.6 * 3.2 mm, and CO 2 gas is introduced at a rate of 1.5 L / min and reacted at 60 °C for 20 s to obtain manganese carbonate microspheres;

[0064] (2) The obtained manganese carbonate is calcined at 500 °C for 5 h to obtain Mn 2 O 3 , Mn 2 O 3 and LiOH·H 2 O are subjected to a hydrothermal reaction at a lithium-to-manganese ratio of 1.1, a temperature of 120 °C, and a reaction time of 48 h. After the reaction is completed, a solid first intermediate product is obtained;

[0065] (3) The obtained first intermediate product is calcined at 400 °C for 4 h to obtain a second intermediate product;

[0066] (4) The obtained second intermediate product is pickled with 0.5 mol / L dilute hydrochloric acid for 24 h at a reaction temperature of 25 °C to obtain a third intermediate product;

[0067] (5) The obtained third intermediate product is filtered, washed with deionized water until the pH of the filtrate is 7, and dried at 60 °C to obtain the manganese oxide lithium ion sieve with a porous structure.

[0068] In this embodiment, the lithium ion adsorption capacity of the obtained product was tested, and the test method and process were the same as those in Embodiment 1. The test results showed that the lithium adsorption capacity of this product was 74.67 mg / g, and the manganese dissolution rate was 1.39%. In the 5-cycle lithium ion adsorption / desorption experiment, the lithium adsorption capacity was stable above 65.43 mg / g, and the manganese dissolution rates were all lower than 1.24%.

[0069] In summary, the lithium manganese oxide ion sieve adsorbent provided by the embodiment of the present invention is specifically a lithium manganese oxide ion sieve with a porous structure, which has the advantages of high adsorption capacity and high lithium selectivity. During the processes of lithium adsorption and desorption regeneration, no structural change occurs. Therefore, this lithium manganese oxide ion sieve has good cycle stability and a long service life.

[0070] The above are only specific embodiments of the present application. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present application, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present application.

Claims

1. A method for preparing a manganese oxide lithium ion sieve adsorbing lithium material, characterized in that: The material is a manganese oxide lithium ion sieve with a porous structure, and the molecular formula is MnO2·0.5H2O.

2. The method for preparing the manganese oxide lithium ion sieve adsorbing lithium material according to claim 1, characterized in that: include: Firstly, Mn(OH)2 suspension was prepared by using MnCl2, ammonia water and ethylene glycol, and then the dispersion medium was fixed in a membrane dispersed microfluidic reactor, and gaseous CO2 was introduced for reaction. After the reaction was completed, manganese carbonate microspheres were obtained. Secondly, the manganese carbonate microspheres are calcined to obtain Mn2O3, which is then placed in an autoclave for hydrothermal reaction with LiOH·H2O to obtain a solid first intermediate product; calcining the first intermediate product to obtain a second intermediate product; treating the second intermediate product with acid to obtain a third intermediate product; The third intermediate product is filtered, washed and dried to obtain the manganese oxide lithium ion sieve with a porous structure.

3. The method for preparing the manganese oxide lithium ion sieve adsorbing lithium material according to claim 2, characterized in that: The membrane dispersion microfluidic reactor for preparing manganese carbonate microspheres comprises seven parts, namely, a Mn(OH)2 suspension inlet 1, a gas inlet 2, a reactor upper cover 3, a dispersion medium 4, a reaction chamber 5, a reaction product outlet 6, and a reactor lower lining 7. A dispersion medium 4 is fixed in the membrane dispersed microfluidic reactor. The Mn(OH)2 suspension in the container enters the upper side of the dispersion medium 4 in the reactor under the action of a pump, and the Mn(OH)2 suspension flows on the upper side of the membrane; CO2 gas passes through the dispersion medium 4 under pressure, and small bubbles are formed on the lower side of the dispersion medium 4. The continuously flowing Mn(OH)2 suspension carries the bubbles away from the lower surface of the dispersion medium 4, and the bubbles and the suspension are efficiently mixed and flow out of the reactor 3.

4. The method for preparing the manganese oxide lithium ion sieve adsorbing lithium material according to claim 2, characterized in that: The amount ratio of ammonia water and MnCl2 for preparing manganese carbonate microspheres is 2:1-5:1, the amount ratio of ethylene glycol and MnCl2 is 5:1-20:1, the CO2 flow rate is 0.5-10L / min, the reaction time is 5-50s, the reaction temperature is 40-80°C, the pore size of the membrane is 2-10μm, and the tube diameter size is 1.0*3mm-1.5*3mm.

5. The method for preparing the manganese oxide lithium ion sieve adsorbing lithium material according to claim 2, characterized in that: The temperature of the manganese carbonate calcination treatment is 500-900° C., and the reaction time is 2-8 hours.

6. The method for preparing the manganese oxide lithium ion sieve adsorbing lithium material according to claim 2, characterized in that: The lithium-manganese ratio of LiOH·H2O to Mn2O3 in the hydrothermal reaction is 1.0-1.3, the temperature is 80-160° C., and the reaction time is 6-48 hours.

7. The method for preparing the manganese oxide lithium ion sieve adsorbing lithium material according to claim 2, characterized in that: The temperature of the first calcination treatment of the intermediate product is 300-500° C., and the reaction time is 2-6 hours.

8. The method for preparing the manganese oxide lithium ion sieve adsorbing lithium material according to claim 2, characterized in that: The concentration of the dilute hydrochloric acid in the acid treatment is 0.5-1.0 mol / L, the temperature is 20-50° C., and the reaction time is 6-48 hours.

9. The method for preparing the manganese oxide lithium ion sieve adsorbing lithium material according to claim 2, characterized in that: The washing treatment is to use deionized water to wash the third intermediate product multiple times until the pH value of the filtrate is 6-8.

10. The method for preparing the manganese oxide lithium ion sieve adsorbing lithium material according to claim 2, characterized in that: The drying process is carried out at a temperature of 60 to 80°C.

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