High-valence Nb < 5 + > doped manganese oxide lithium ion sieve and preparation method and application thereof

Abstract

The invention discloses a high-valence Nb < 5 + > doped manganese oxide lithium ion sieve as well as a preparation method and application thereof, and belongs to the technical field of preparation of lithium ion sieves. The preparation method comprises the following steps: synthesizing a LiMnO2 precursor step by step, calcining manganese carbonate into Mn2O3, and carrying out hydrothermal reaction with LiOH; nbCl5 and LiMnO2 are mixed and calcined, Nb < 5 + > is doped and replaces part of Mn < 3 + > ions according to the proportion of 0.02-0.10, and a stable solid solution structure is formed. According to the lithium ion sieve, the average valence state of manganese can be improved by doping high-valence-state Nb < 5 + >, so that the disproportionation reaction of Mn < 3 + > is inhibited, the solution loss of manganese is reduced, the skeleton structure of spinel is stabilized, and lattice distortion is relieved. The adsorption capacity is 30.0-35.5 mg g <-1 >, the adsorption capacity after circulation is maintained to be 28-35 mg g <-1 >, and the manganese dissolution loss rate is 3.0-4.0%. The adsorbent is applied to extraction of lithium from salt lake brine, can enhance selective adsorption of Li < + >, overcomes the problem of performance degradation of traditional adsorbents, efficiently and stably extracts lithium, and has wide prospects and economic values.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion sieve preparation technology, specifically relating to high-valence Nb. 5+ Manganese oxide-doped lithium-ion sieves, their preparation methods, and applications. Background Technology

[0002] Against the backdrop of the accelerated global energy system transition to low-carbon development and the rapid expansion of the new energy vehicle market, lithium has become a strategically important metal resource in the 21st century, indispensable in clean energy technologies. Its unique physical and chemical properties make lithium and lithium compounds play an essential role in clean energy technologies. It is estimated that the total global lithium resources amount to approximately 89 million tons, with over 62% found in salt lake brines. However, existing extraction technologies suffer from low efficiency and high costs. Salt lakes in regions like Qinghai, China, have low background lithium-ion concentrations, high magnesium-to-lithium ratios, and interference from multiple coexisting ions, making separation difficult. Therefore, developing efficient, green, and economical lithium extraction processes is urgently needed. Among numerous adsorption-based lithium extraction materials, lithium-ion sieve adsorbents are mainly classified into three categories: aluminum-based (LiAl-LDHs), manganese-based (LMO), and titanium-based (LTO). Among these, spinel-type manganese-based lithium-ion sieves (Li... 1.6 Mn 1.6 O₄⁻ has attracted widespread attention from researchers due to its high theoretical adsorption capacity (up to 72.3 mg / g), excellent ion selectivity, and recycling potential. However, this material also has significant shortcomings: on the one hand, the Jahn-Teller effect causes lattice distortion, which limits its practical performance; on the other hand, the manganese in its crystals is in a mixed +3 and +4 valence state, and Mn₂ is easily generated during acid washing. 3+ The disproportionation reaction produces soluble Mn 2+ This leads to manganese dissolution and structural collapse, affecting the material's stability and recyclability. To improve the stability and cycling performance of LMO, researchers have implemented various modification strategies in recent years, including surface modification, ion doping, morphology control, and coating. Among these, ion doping is considered an effective method due to its advantages such as controllable lattice composition, suppression of manganese dissolution, and enhanced structural stability. The incorporation of suitable elements can not only improve the material's resistance to Li... + The adsorption performance is excellent, and the crystal structure can be stabilized through ion replacement, thereby reducing the leaching loss of manganese. Currently, the selection of doping elements is mostly +1 to +3 valence ions. Research results show that doping with ions of different valence states can effectively increase the average valence state of Mn atoms in manganese-based lithium ion sieves. Doping with higher valence states is currently less studied. Theoretically, high-valence ion doping entering the ion sieve will replace some Mn atoms, thus having a more significant effect on increasing the average valence state of Mn. Summary of the Invention

[0003] To address the lattice distortion caused by the Jahn-Teller effect in existing manganese-based lithium ion sieves, and the issue of Mn during acid leaching... 3+ The problem of manganese dissolution and structural collapse caused by disproportionation, and the current state of technology where existing modification strategies are ineffective in suppressing manganese dissolution and enhancing structural stability, are addressed by this invention, which provides a high-valence Nb... 5+ Manganese oxide-doped lithium-ion sieves, their preparation methods, and applications.

[0004] To achieve the above objectives, the present invention employs the following technical solution: This invention provides a Nb 5+ The preparation method of doped manganese oxide lithium-ion sieve includes: Step 1: Grind and mix LiMnO2 and NbCl5, then calcine to obtain NbCl5. 5+ Doped manganese oxide lithium-ion sieve precursor; Step 2, Nb 5+ The doped manganese oxide lithium-ion sieve precursor was dispersed in an acid solution, acid-washed, filtered, and cleaned to obtain Nb. 5+ Lithium-ion sieve doped with manganese oxide.

[0005] In step 1, the preparation of LiMnO2 specifically includes: calcining manganese carbonate to obtain Mn2O3, and reacting Mn2O3 with LiOH to obtain LiMnO2.

[0006] Preferably, the manganese carbonate is calcined at a temperature of 750~850℃ for 4~6 hours.

[0007] Preferably, the molar ratio of Mn2O3 to LiOH is 1:(4~5), the reaction temperature is 100~140℃, and the reaction time is 40~60h.

[0008] In step 1, the mass ratio of LiMnO2 to NbCl5 is 1:(0.05~0.06).

[0009] In step 1, the calcination temperature is 350~550℃ and the calcination time is 5~7h.

[0010] In step 2, the Nb 5+ The mass-to-volume ratio of the doped manganese oxide lithium ion sieve precursor to the acid solution is 1:(100~200)g / mL.

[0011] In step 2, the acid used for pickling is any one of hydrochloric acid, sulfuric acid, or nitric acid, and the pickling time is 20 h to 26 h.

[0012] The present invention provides Nb obtained by the above preparation method. 5+ The Nb-doped manganese oxide lithium-ion sieve5+ The chemical formula of the doped manganese oxide lithium-ion sieve is H. 1.6 Mn 1.6-x Nb x O4, x = 0.02~0.10, the adsorption capacity of the manganese oxide lithium ion sieve is 30.0 mg g. -1 ~35.5 mg g -1 The adsorption capacity after the cyclic experiment was 28 mg g. -1 ~35 mg g -1 The manganese loss is 3.0%~4.0%.

[0013] The present invention provides the Nb 5+ Application of doped manganese oxide lithium ion sieves in lithium ion extraction from salt lake brine.

[0014] Compared with the prior art, the present invention achieves the following technical effects: The preparation method provided by this invention involves calcining a mixture of NbCl5 and LiMnO2, where Nb... 5+ By entering the spinel lattice in a high valence state, ion substitution suppresses lattice distortion caused by the Jahn-Teller effect, while simultaneously increasing the average valence state of manganese and reducing Mn content during acid pickling. 3+ The disproportionation reaction occurs; the calcination process causes Nb to undergo disproportionation. 5+ It forms a stable solid solution structure with manganese oxide, providing structural support for subsequent acid washing; by treating the precursor with acid solution, Nb... 5+ The stable lattice framework formed by doping can effectively suppress the dissolution of manganese ions and maintain the integrity of the ion sieve skeleton, thereby solving the problem of structural collapse during recycling. The grinding and mixing process ensures uniform dispersion of Nb elements, and the calcination temperature and time control optimize the precursor crystal structure. The acid washing conditions are selected to balance lithium insertion / extraction efficiency and manganese stability, thereby improving the structural stability and anti-dissolution performance of manganese-based lithium ion sieves. This provides a new preparation method to solve the problems existing in manganese-based lithium ion sieves and is expected to improve their performance.

[0015] Furthermore, by synthesizing the LiMnO2 precursor stepwise, manganese carbonate is first calcined at high temperature to convert it into Mn2O3. This thermal decomposition reaction achieves the crystal transformation of manganese oxide, providing an intermediate product with a stable crystal structure for the subsequent lithiation reaction. Mn2O3 is then subjected to a hydrothermal reaction with LiOH, utilizing an alkaline environment to encourage lithium ions to intercalate into the manganese oxide lattice, forming LiMnO2 with a spinel structure. The choice of manganese carbonate as the starting material is more advantageous than other manganese sources for controlling the purity of the calcined product. The stepwise design of calcination and lithiation avoids lattice defects that may occur during the direct synthesis of LiMnO2, ensuring that the precursor material has a complete crystal structure, which is crucial for subsequent Nb synthesis.5+ Doping provides a stable matrix material.

[0016] The high valence state Nb provided by this invention 5+ Manganese oxide-doped lithium-ion sieves, containing Nb 5+ Cations were successfully doped into the manganese oxide lattice, forming a lithium-ion sieve with a specific chemical composition, thus enabling the control of intrinsic defects in manganese-based materials. Nb 5+ Part of the Mn was replaced with a doping ratio of x = 0.02~0.10. 3+ The high valence state of ions can increase the average valence state of manganese and suppress Mn. 3+ The disproportionation reaction reduces the dissolution loss of manganese during pickling; simultaneously, Nb 5+ Ionic radius and Mn 3+ Similar to other materials, this material can stabilize the spinel structure and mitigate lattice distortion caused by the Jahn-Teller effect; its adsorption capacity is 30.0–35.5 mg g. -1 While maintaining high adsorption efficiency, the accessibility of active sites was optimized through doping; the adsorption capacity remained at 28–35 mgg after cycling. -1 Nb 5+ The doping effectively enhanced the structural stability of the material; the manganese dissolution rate was controlled at 3.0%–4.0%, further verifying the inhibitory effect of doping on manganese dissolution. This invention utilizes high-valence Nb... 5+ Manganese oxide-doped lithium-ion sieves achieve a balance between improved adsorption performance and cycle life through multi-scale synergistic effects.

[0017] The application provided by this invention, Nb 5+ Doped manganese oxide lithium-ion sieves are used for lithium-ion extraction from salt lake brines. Targeting the unique high magnesium-to-lithium ratio characteristic of salt lake brines, the doped ion sieves are optimized for Li... + The charge distribution at the adsorption sites enhances the adhesion of Li to Li. + By leveraging its selective adsorption capacity, this modified material was directly introduced into the brine system of a salt lake. Utilizing its stable spinel structure and optimized ion channels, it overcame the performance degradation problem of traditional manganese-based adsorbents under strongly alkaline and high ionic strength environments. This enabled efficient and stable extraction of lithium ions from actual brine, reducing extraction costs. It provides an effective technical means to solve the global lithium resource extraction problem, especially the lithium ion extraction problem in salt lakes in Qinghai, China, and has broad application prospects and significant economic value. Attached Figure Description

[0018] Figure 1 The XRD characterization spectra of undoped LMO and Nb-LMO with different doping ratios are shown in the present invention. Figure 2 The present invention is Nb-Li 1.6Mn 1.6 SEM, TEM, and EDS-mapping images of O4 samples, where a is the SEM image of LMO, b and c are the TEM images of LMO, d is the HRTEM image of LMO, e is the SEM image of Nb-LMO, f and g are the TEM images of Nb-LMO, h is the HRTEM image of Nb-LMO, and im is the EDS elemental spectrum of Nb-LMO. Figure 3 This invention relates to the adsorption of Li by Nb-doped LMO with different ratios. + Adsorption capacity; Figure 4 Adsorption experiments were conducted at different pH values ​​for this invention; Figure 5 This refers to the adsorption capacity at different equilibrium concentrations of the present invention; Figure 6 Selective adsorption experiments of different ions for this invention; Figure 7 Nb of the present invention 5+ The doped Nb-HMO underwent 10 adsorption / desorption cycles of Li. + Cyclic experiment; Detailed Implementation To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. 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 should fall within the scope of protection of the present invention.

[0019] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0020] Unless otherwise specified, all experimental materials used in this invention are commercially available products well known to those skilled in the art.

[0021] I. Specific Implementation Cases Example 1 This embodiment provides a high-valence Nb 5+ The specific preparation process of the manganese oxide-doped lithium-ion sieve is as follows: (1) Preparation of LiMnO2 10 g of MnCO3 was placed in a high-temperature furnace and calcined in air at 800 °C for 5 hours. After calcination, the furnace was allowed to cool naturally to room temperature to obtain solid Mn2O3. 10 g of the prepared Mn2O3 solid was weighed and placed in a polytetrafluoroethylene (PTFE) liner. 64 mL of a 4 mol / L LiOH·H2O solution was slowly added to the PTFE liner containing Mn2O3. The mixture was thoroughly stirred using a magnetic stirrer and then transferred to a high-pressure reactor. The reactor was placed in an oven and reacted at 120 °C for 48 hours. After the reaction, the mixture was allowed to cool naturally and then filtered. It was repeatedly washed with deionized water until neutral to remove residual impurity ions. The washed solid product was dried overnight at 60 °C to obtain LiMnO2.

[0022] (2) Doping with Nb 5+ Nb-LMO, a lithium-ion sieve precursor 3 g of LiMnO2 and 0.1727 g of NbCl5 were mixed to obtain a mixture. The mixture was then placed in a mortar and ground thoroughly until homogeneous. The ground mixture was transferred to a muffle furnace and calcined at 400 °C for 6 hours. After calcination, the muffle furnace was allowed to cool naturally to room temperature to obtain doped Nb. 5+ Nb-LMO, a lithium-ion sieve precursor.

[0023] (3) Preparation of lithium-ion sieves (Nb-HMO and HMO) Accurately weigh 2 g of doped Nb 5+ The lithium-ion sieve precursor Nb-LMO was dispersed in 200 mL of 0.5 mol / L HCl solution. The mixture was stirred with a magnetic stirrer for 12 hours, followed by acid washing. After acid washing, the solid product was separated from the acid washing solution by vacuum filtration. The solid product obtained by vacuum filtration was repeatedly washed with deionized water until the filtrate reached neutrality to remove residual H+. + and Cl - Plasma ionization; then the resulting solid product was dried overnight at 60 °C to obtain Nb-doped Nb. 5+ The lithium-ion sieve is 2% Nb-HMO.

[0024] Example 2 This embodiment provides a high-valence Nb 5+ The specific preparation process of the manganese oxide-doped lithium-ion sieve is as follows: (1) Preparation of LiMnO2 10 g of MnCO3 was placed in a high-temperature furnace and calcined in air at 800 °C for 5 hours. After calcination, the furnace was allowed to cool naturally to room temperature to obtain solid Mn2O3. 10 g of the prepared Mn2O3 solid was weighed and placed in a polytetrafluoroethylene (PTFE) liner. 64 mL of a 4 mol / L LiOH·H2O solution was slowly added to the PTFE liner containing Mn2O3. The mixture was thoroughly stirred using a magnetic stirrer and then transferred to a high-pressure reactor. The reactor was placed in an oven and reacted at 120 °C for 48 hours. After the reaction, the mixture was allowed to cool naturally and then filtered. It was repeatedly washed with deionized water until neutral to remove residual impurity ions. The washed solid product was dried overnight at 60 °C to obtain LiMnO2.

[0025] (2) Doping with Nb 5+ Nb-LMO, a lithium-ion sieve precursor 3 g of LiMnO2 and 0.4316 g of NbCl5 were mixed to obtain a mixture. The mixture was placed in a mortar and ground thoroughly until homogeneous. The ground mixture was then transferred to a muffle furnace and calcined at 400 °C for 6 hours. After calcination, the muffle furnace was allowed to cool naturally to room temperature to obtain doped Nb. 5+ Nb-LMO, a lithium-ion sieve precursor.

[0026] (3) Preparation of lithium-ion sieves (Nb-HMO and HMO) Accurately weigh 2 g of doped Nb 5+ The lithium-ion sieve precursor Nb-LMO was dispersed in 200 mL of 0.5 mol / L HCl solution. The mixture was stirred with a magnetic stirrer for 12 hours, followed by acid washing. After acid washing, the solid product was separated from the acid washing solution by vacuum filtration. The solid product obtained by vacuum filtration was repeatedly washed with deionized water until the filtrate reached neutrality to remove residual H+. + and Cl - Plasma ionization; then the resulting solid product was dried overnight at 60 °C to obtain Nb-doped Nb. 5+ The lithium-ion sieve contains 5% Nb-HMO.

[0027] Example 3 This embodiment provides a high-valence Nb 5+ The specific preparation process of the manganese oxide-doped lithium-ion sieve is as follows: (1) Preparation of LiMnO2 10 g of MnCO3 was placed in a high-temperature furnace and calcined in air at 800 °C for 5 hours. After calcination, the furnace was allowed to cool naturally to room temperature to obtain solid Mn2O3. 10 g of the prepared Mn2O3 solid was weighed and placed in a polytetrafluoroethylene (PTFE) liner. 64 mL of a 4 mol / L LiOH·H2O solution was slowly added to the PTFE liner containing Mn2O3. The mixture was thoroughly stirred using a magnetic stirrer and then transferred to a high-pressure reactor. The reactor was placed in an oven and reacted at 120 °C for 48 hours. After the reaction, the mixture was allowed to cool naturally and then filtered. It was repeatedly washed with deionized water until neutral to remove residual impurity ions. The washed solid product was dried overnight at 60 °C to obtain LiMnO2.

[0028] (2) Doping with Nb 5+ Nb-LMO, a lithium-ion sieve precursor 3 g of LiMnO2 and 0.8633 g of NbCl5 were mixed to obtain a mixture. The mixture was then placed in a mortar and ground thoroughly until homogeneous. The ground mixture was transferred to a muffle furnace and calcined at 400 °C for 6 hours. After calcination, the muffle furnace was allowed to cool naturally to room temperature to obtain doped Nb. 5+ Nb-LMO, a lithium-ion sieve precursor.

[0029] (3) Preparation of lithium-ion sieves (Nb-HMO and HMO) Accurately weigh 2 g of doped Nb 5+ The lithium-ion sieve precursor Nb-LMO was dispersed in 200 mL of 0.5 mol / L HCl solution. The mixture was stirred with a magnetic stirrer for 12 hours, followed by acid washing. After acid washing, the solid product was separated from the acid washing solution by vacuum filtration. The solid product obtained by vacuum filtration was repeatedly washed with deionized water until the filtrate reached neutrality to remove residual H+. + and Cl - Plasma ionization; then the resulting solid product was dried overnight at 60 °C to obtain Nb-doped Nb. 5+ The lithium-ion sieve contains 10% Nb-HMO.

[0030] Comparative Example This embodiment provides a method for undoped high-valence Nb. 5+ The specific preparation process of the manganese oxide lithium-ion sieve is as follows: (1) Preparation of LiMnO2 10 g of MnCO3 was placed in a high-temperature furnace and calcined in air at 800 °C for 5 hours. After calcination, the furnace was allowed to cool naturally to room temperature to obtain solid Mn2O3. 10 g of the prepared Mn2O3 solid was weighed and placed in a polytetrafluoroethylene (PTFE) liner. 64 mL of a 4 mol / L LiOH·H2O solution was slowly added to the PTFE liner containing Mn2O3. The mixture was thoroughly stirred using a magnetic stirrer and then transferred to a high-pressure reactor. The reactor was placed in an oven and reacted at 120 °C for 48 hours. After the reaction, the mixture was allowed to cool naturally and then filtered. It was repeatedly washed with deionized water until neutral to remove residual impurity ions. The washed solid product was dried overnight at 60 °C to obtain LiMnO2.

[0031] (2) Undoped lithium-ion sieve precursor Nb-LMO 3g of LiMnO2 was placed in a mortar and ground thoroughly until homogeneous. The ground mixture was then transferred to a muffle furnace and calcined at 400 °C for 6 hours. After calcination, the muffle furnace was allowed to cool naturally to room temperature to obtain the undoped lithium-ion sieve precursor LMO.

[0032] (3) Preparation of lithium-ion sieve HMO Accurately weigh 2 g of undoped lithium-ion sieve precursor LMO and disperse it in 200 mL of 0.5 mol / L HCl solution. Stir the mixture with a magnetic stirrer for 12 hours, then perform acid washing. After acid washing, filter to separate the solid product from the acid washing solution. Wash the filtered solid product repeatedly with deionized water until the filtrate is neutral to remove residual H+. + and Cl - Plasma ionization was performed; then the resulting solid product was dried overnight at 60 °C to obtain undoped lithium-ion sieve HMO. II. Performance Testing Experiment See appendix Figure 1 XRD characterization was performed on undoped LMO and Nb-LMO with different doping ratios. The results showed that the diffraction peaks of undoped LMO and Nb-LMO with different doping ratios were similar to those of Li. 1.6 Mn 1.6 The O4 standard card comparison shows good results, indicating the successful preparation of a spinel-structured manganese-based lithium-ion sieve. Furthermore, doping did not alter the spinel structure of the adsorbent, even at 5% and 10% Nb content. 5+ The presence of tiny impurity peaks in the XRD pattern of doped materials indicates that excessive doping may result in the formation of impurities.

[0033] See appendix Figure 2The microstructure of LMO and 2%Nb-LMO was characterized. Both LMO and 2%Nb-LMO exhibited the typical disordered granular aggregation of manganese-based lithium-ion sieves, indicating that doping did not change the material morphology. EDS characterization of 2%Nb-LMO showed that Mn, O, and Nb were uniformly distributed, proving the success of the doping.

[0034] See appendix Figure 3 Li adsorption was carried out using Nb-doped HMO with different ratios. + experiment.

[0035] 0.05 g of each of the samples from Examples 1, 2, 3, and the comparative example were added to a 100 mg / L LiCl solution, shaken at 25°C, and samples were taken at different times. After filtration through a filter membrane, clear solutions were obtained. Ion concentrations were tested using AAS, and adsorption capacity was calculated. From Li... + In terms of adsorption capacity, the adsorption capacity of 2% doped HMO is higher than that of undoped HMO. The adsorption capacity decreases after doping at 5% and 10% ratios. Therefore, Example 1 was selected as the optimal doping ratio for subsequent experiments.

[0036] See appendix Figure 4 Adsorption experiments were conducted at different pH values ​​to explore the optimal adsorption conditions. 50 mL of 100 mg / L LiCl solutions with pH values ​​of 6, 8, 9, 10, 11, and 12 were taken. Two groups of LiCl solutions were prepared for each pH value, and 0.05 g of Example 1 and the comparative example were added to each group. The solutions were shaken at 25°C for 12 h, and samples were taken to calculate the adsorption capacity. At pH 6, the adsorption capacities of the comparative example and Example 1 were 1.25 mg / g and 2.75 mg / g, respectively. When the pH was raised to 12, the adsorption capacities of HMO and 2% doped Nb-HMO were 29.75 mg / g and 34.75 mg / g, respectively. This indicates that a strongly alkaline environment is more suitable for Li+ adsorption, and the adsorption capacity of 2%-Nb-HMO is greater than that of undoped HMO. Therefore, subsequent experiments will be conducted at pH 12.

[0037] See appendix Figure 5 Two groups of 50 mL samples were taken, each with an initial concentration of 20, 40, 60, 80, 100, and 120 mg / L of Li. + The solutions were mixed with 0.05 g of the comparative example and Example 1, respectively, and shaken at 25°C for 12 h. After the reaction was completed, samples were taken to detect Li. + Concentration, calculate equilibrium concentration and adsorption capacity.

[0038] The results are shown in the figure. The adsorption capacity increases with Li +The adsorption capacity of Example 1 increased with increasing equilibrium concentration, and the adsorption capacity of Example 1 was consistently greater than that of the comparative example. When the Li+ equilibrium concentration was around 95 mg / L, the adsorption capacities of Example 1 and the comparative example were the highest, at 41.9 mg / g and 34.9 mg / g, respectively. This indicates that at different equilibrium concentrations, the adsorption capacity of Example 1 was greater than that of the undoped comparative example.

[0039] See appendix Figure 6 Selective adsorption experiments were conducted using brine from Xitaijinaier Salt Lake.

[0040] The composition of the brine from Xitaijinaier Salt Lake used in the test is shown in the table below:

[0041] Two groups of 0.05 g of Example 1 were added to 50 mL of Xitaijinaier Salt Lake brine and LiCl solution for comparison. The mixture was shaken at 25°C for 12 h, and samples were taken to measure the concentration of different ions. The results are shown in the figure.

[0042] As can be seen from the figure, in actual brines with a high Mg / Li ratio, such as the Xitaijinaier Salt Lake brine, Example 1 exhibits a good adsorption capacity. Compared to the prepared LiCl solution, the adsorption capacity of Example 1 in the reagent brine is 25.5 mg / g, which, while not significantly different from the prepared LiCl solution, demonstrates that Example 1 exhibits good selectivity and adsorption capacity for lithium ions in complex environments.

[0043] See appendix Figure 7 Adsorption / desorption cycle experiment: 10 adsorption / desorption cycles of Li were performed on Example 1. + Cyclic experiment.

[0044] 0.05 g of Example 1 and the undoped comparative example were added to 100 mg / L LiCl solution, shaken for 12 h, and then samples were taken. After filtration, the solids were dried, acid-washed with 0.5 mol / L HCl for 12 h, filtered again, and adsorbed again. The above steps were repeated for the cyclic experiment. The adsorption capacity decay of Example 1 was lower and higher than that of the comparative example. After 10 cycles, the adsorption capacity of Example 1 remained at 28.85 mg / g. During the 10 cycles, the dissolution loss of Mn in Example 1 remained at about 4.0%, lower than the 4.7% of the comparative example, indicating that Nb... 5+ Doping reduces the dissolution loss of Mn.

[0045] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A Nb 5+ A method for preparing a doped manganese oxide lithium ion sieve, characterized by, The application relates to a method for preparing LiMnO2-NbCl5 composite oxide. Step 1, LiMnO2 was mixed with NbCl5 by grinding, and calcined to obtain Nb 5+ Doped manganese oxide lithium ion sieve precursor; Step 2, Nb 5+ The doped manganese oxide lithium ion sieve precursor is dispersed in an acid solution, pickled, suction filtered, washed, and Nb 5+ doped manganese oxide lithium ion sieve.

2. A Nb 5+ The method for preparing a doped manganese oxide lithium ion sieve is characterized by, The preparation of the LiMnO2 in step 1 specifically comprises the following steps: calcining manganese carbonate to obtain Mn2O3, and reacting the Mn2O3 with LiOH to obtain LiMnO2.

3. A Nb 5+ Process for the preparation of doped manganese oxide lithium ion sieves, characterized in that, The calcining temperature of the manganese carbonate is 750-850 DEG C, and the calcining time is 4-6 h.

4. A Nb 5+ Process for the preparation of doped manganese oxide lithium ion sieves, characterized in that, The molar ratio of the Mn2O3 to the LiOH is 1: (4-5), the reaction temperature is 100-140 DEG C, and the reaction time is 40-60 h.

5. A Nb 5+ Process for the preparation of doped manganese oxide lithium ion sieves, characterized in that, In step 1, the mass ratio of the LiMnO2 to the NbCl5 is 1: (0.05-0.06).

6. A Nb 5+ Process for the preparation of doped manganese oxide lithium ion sieves, characterized in that, In step 1, the calcining temperature is 350-550 DEG C, and the calcining time is 5-7 h.

7. A Nb 5+ Process for the preparation of doped manganese oxide lithium ion sieves, characterized in that, In Step 2, the Nb 5+ The mass-volume ratio of the doped manganese oxide lithium ion sieve precursor to the acid solution is 1: (100-200) g / mL.

8. A Nb 5+ Process for the preparation of doped manganese oxide lithium ion sieves, characterized in that, In step 2, the pickling acid is any one of hydrochloric acid, sulfuric acid and nitric acid, and the pickling time is 20-26 h.

9. The Nb obtained by the production process according to any one of claims 1 to 8 5+ Doped manganese oxide lithium ion sieve, characterized in that, The Nb 5+ The chemical formula of the doped manganese oxide lithium ion sieve is H 1.6 Mn 1.6-x The Nb x O4, x = 0.02 ~ 0.10, the adsorption capacity of the manganese oxide lithium ion sieve is 30.0 mg g -1 ~ 35.5 mg g -1 , the adsorption capacity after the cycle experiment is 28 mg g -1 ~ 35 mg g -1 , and the manganese dissolution loss is 3.0 % ~ 4.0 %.

10. The Nb of claim 9 5+ Use of doped manganese oxide lithium ion sieve in extracting lithium ions from salt lake brine.

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