Silicon-doped titanium-based lithium ion sieves, methods of making and using the same
By introducing silicon into titanium-based lithium-ion sieves, controlling the crystal growth rate and perfecting defects, a small-particle-size lithium-ion sieve precursor was prepared. This solved the caking problem during high-temperature calcination, improved adsorption capacity and selectivity, enhanced acid resistance, and made it suitable for industrial production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- BEIJING HUATEYUAN TECHNOLOGY CO LTD
- Filing Date
- 2024-02-05
- Publication Date
- 2026-06-23
AI Technical Summary
Existing titanium-based lithium-ion sieves are prone to over-burning and caking during high-temperature calcination, resulting in decreased adsorption capacity and lithium-ion selectivity, as well as insufficient acid resistance.
Silicon was introduced as an additive into titanium and lithium sources, and silicon-doped titanium-based lithium-ion sieves were prepared through steps such as grinding, calcination, pulping, microwave drying and high-temperature sintering. The crystal growth rate was controlled and crystal defects were improved to form small-particle-size lithium-ion sieve precursors.
It improves the adsorption capacity and selectivity of lithium-ion sieves, enhances acid resistance, and reduces titanium dissolution rate, making it suitable for large-scale industrial production.
Smart Images
Figure CN118026251B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of ion sieve preparation technology, and in particular to a silicon-doped titanium-based lithium ion sieve, its preparation method, and its application. Background Technology
[0002] With the popularity and widespread adoption of new energy vehicles, China's demand for lithium salts is increasing. Extracting lithium from salt lakes is an effective way to address the supply shortage. For lithium extraction from weakly alkaline salt lakes in Tibet, China, acid- and alkali-resistant β-H₂TiO₃ is typically used as a lithium-ion sieve adsorbent. β-H₂TiO₃ is obtained by acidifying the precursor β-Li₂TiO₃ with hydrochloric acid or sulfuric acid.
[0003] The titanium-based lithium-ion sieve precursor β-Li₂TiO₃ is obtained by high-temperature calcination of a mixture of titanium sources (metatinic acid, titanium dioxide) and lithium sources (lithium carbonate, lithium hydroxide). During the high-temperature calcination process, when the temperature exceeds 800℃, the reaction becomes too vigorous, and the precursor β-Li₂TiO₃ is prone to over-burning and hardening, resulting in a significant decrease in its adsorption capacity. However, when the temperature is below 800℃, the presence of numerous defect sites in the crystal leads to a decrease in its selectivity for lithium ions. Therefore, it is necessary to find an additive to be added to the titanium and lithium sources for high-temperature reaction, which can suppress the over-burning and hardening of the precursor β-Li₂TiO₃ at high temperatures, ensuring that its adsorption capacity meets the requirements and that it maintains excellent lithium-ion selectivity.
[0004] In view of this, the present invention is hereby proposed. Summary of the Invention
[0005] One of the objectives of this invention is to provide a silicon-doped titanium-based lithium-ion sieve, which aims to solve the technical problems of small adsorption capacity, numerous crystal defects, high titanium dissolution loss, and low lithium-ion selectivity in existing titanium-based lithium-ion sieves.
[0006] The second objective of this invention is to provide a method for preparing a silicon-doped titanium-based lithium-ion sieve.
[0007] The third objective of this invention is to provide an application of a silicon-doped titanium-based lithium-ion sieve.
[0008] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted:
[0009] The first aspect of the present invention provides a silicon-doped titanium-based lithium-ion sieve with the chemical formula β-H₂Ti. 1-x Si x O3;
[0010] Where 0 < x ≤ 0.1.
[0011] Furthermore, the silicon-doped titanium-based lithium-ion sieve has an adsorption capacity of 22-25 mg / g and a titanium loss of 0.10-0.15%.
[0012] Preferably, the specific surface area is 14.3-15 m². 2 / g.
[0013] A second aspect of the present invention provides a method for preparing the silicon-doped titanium-based lithium-ion sieve, comprising the following steps:
[0014] A. Mix and grind metatitanic acid and metasilicic acid, and then calcine to obtain a blend containing amorphous TiO2 and amorphous SiO2;
[0015] B. After mixing the lithium source and the blend, deionized water is added and the mixture is pulped to obtain a slurry. The slurry is then microwave-dried and pulverized to obtain a powdered material.
[0016] C. The powdered material is sintered at high temperature to obtain a silicon-doped titanium-based lithium-ion sieve precursor.
[0017] D. The titanium-based lithium-ion sieve precursor is activated in hydrochloric acid solution. After activation, the material is separated into solid and liquid phases, dried and pulverized to obtain the silicon-doped titanium-based lithium-ion sieve.
[0018] Furthermore, in the lithium source, the metatitanic acid and the metasilicic acid, the molar ratio of Li, Ti and Si is 2.0-2.3:0.9-0.99:0.01-0.1.
[0019] Furthermore, in step A, the grinding time is 0.5-2 hours.
[0020] Preferably, in step A, the calcination temperature is 400-600℃ and the time is 2-5 hours.
[0021] Preferably, in step A, the heating rate during roasting is 2-6°C / min.
[0022] Furthermore, in step B, the amount of deionized water added is 80-120% of the mass of the lithium source and the blend.
[0023] Preferably, in step B, the pulping time is 1-2 hours.
[0024] Preferably, in step B, the particle size of the powdered material is 50-100 mesh.
[0025] Furthermore, in step C, the high-temperature sintering temperature is 800-950℃, and the time is 3-6 hours.
[0026] Preferably, in step C, the heating rate of the high-temperature sintering is 3-8℃ / min.
[0027] Further, in step D, the concentration of the hydrochloric acid solution is 0.1-1 mol / L.
[0028] Furthermore, in step D, the activation temperature is 40-60°C.
[0029] Preferably, in step D, the hydrochloric acid solution is changed every 4-6 hours during the activation process, and the activation process is repeated 2-4 times.
[0030] A third aspect of the present invention provides the application of the silicon-doped titanium-based lithium-ion sieve as a lithium extraction adsorbent in the production of lithium salts.
[0031] Compared with the prior art, the present invention has at least the following beneficial effects:
[0032] The silicon-doped titanium-based lithium-ion sieve provided by this invention introduces silicon into its crystal structure. Highly electronegative tetravalent silicon atoms replace a small portion of low electronegative tetravalent titanium atoms. This breaks the regular rapid formation of titanium-oxygen bonds and the regular rapid growth of [TiO6] octahedra, controlling the crystal growth rate and perfecting crystal defects at high temperatures. This yields a small-particle-size titanium-based lithium-ion sieve precursor β-Li2TiO3 under high-temperature conditions, solving the technical problem of over-burning and caking of the β-Li2TiO3 precursor. It also solves the technical problem that the synthesized β-Li2TiO3 precursor cannot simultaneously possess high adsorption capacity and high lithium-ion selectivity at high temperatures. Furthermore, the higher stability of Si-O bonds compared to Ti-O bonds results in a synthesized lithium-ion sieve with higher acid resistance and lower titanium dissolution rate.
[0033] The present invention provides a method for preparing silicon-doped titanium-based lithium-ion sieves by introducing silicon as an additive into the raw materials of metatitanic acid and lithium source, thereby controlling the crystal growth rate and improving crystal defects, and obtaining a small-particle-size doped titanium-based lithium-ion sieve precursor β-Li₂Ti. 1-x Si x O3 solves the technical problem of over-burning and caking in titanium-based lithium-ion sieve precursors. This preparation method is continuous, highly mechanized, and has strong controllability of process nodes, making it suitable for large-scale industrial production.
[0034] The silicon-doped titanium-based lithium-ion sieve provided by this invention serves as a lithium extraction adsorbent, offering a better adsorbent for lithium salt production, improving lithium salt production efficiency, and promoting the development of downstream industries. Attached Figure Description
[0035] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0036] Figure 1 β-H2Ti provided for Test Example 1 0.95 Si 0.05 XRD spectra of O3 and β-H2TiO3;
[0037] Figure 2 β-H2Ti provided for Test Example 1 0.95 Si 0.05 Magnified view of the (002) crystal plane of O3 and β-H2TiO3;
[0038] Figure 3 β-H2Ti provided for Test Example 2 0.95 Si 0.05 Scanning electron microscope image of O3;
[0039] Figure 4 Scanning electron microscope image of β-H2TiO3 provided for test example 2;
[0040] Figure 5 β-H2Ti provided for test example 3 0.95 Si 0.05 XRD spectra of O3 and β-H2TiO3;
[0041] Figure 6 β-H2Ti provided for test example 3 0.95 Si 0.05 Magnified view of the (002) crystal plane of O3 and β-H2TiO3;
[0042] Figure 7 β-H2Ti provided for test example 4 0.95 Si 0.05 Scanning electron microscope image of O3;
[0043] Figure 8 Scanning electron microscope image of β-H2TiO3 provided for test example 4;
[0044] Figure 9 The adsorption performance graph provided for Test Example 6;
[0045] Figure 10 The Li / Na performance graph provided for Test Example 6. Detailed Implementation
[0046] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.
[0047] In the following, the terms “comprising,” “having,” and their cognates, which may be used in various embodiments of the invention, are intended only to indicate a particular feature, number, step, operation, element, component, or combination thereof, and should not be construed as excluding, firstly, the presence of one or more other features, numbers, steps, operations, elements, components, or combinations thereof, or adding the possibility of one or more features, numbers, steps, operations, elements, components, or combinations thereof.
[0048] The first aspect of the present invention provides a silicon-doped titanium-based lithium-ion sieve with the chemical formula β-H₂Ti. 1-x Si x O3;
[0049] Where 0 < x ≤ 0.1.
[0050] The silicon-doped titanium-based lithium-ion sieve provided by this invention introduces silicon into its crystal structure. Highly electronegative tetravalent silicon atoms replace a small portion of low electronegative tetravalent titanium atoms. This breaks the regular rapid formation of titanium-oxygen bonds and the regular rapid growth of [TiO6] octahedra, controlling the crystal growth rate and perfecting crystal defects at high temperatures. This yields a small-particle-size titanium-based lithium-ion sieve precursor β-Li2TiO3 under high-temperature conditions, solving the technical problem of over-burning and caking of the β-Li2TiO3 precursor. It also solves the technical problem that the synthesized β-Li2TiO3 precursor cannot simultaneously possess high adsorption capacity and high lithium-ion selectivity at high temperatures. Furthermore, the higher stability of Si-O bonds compared to Ti-O bonds results in a synthesized lithium-ion sieve with higher acid resistance and lower titanium dissolution rate.
[0051] In the specific implementation of this invention, the typical, but not limiting, chemical formula of the silicon-doped titanium-based lithium-ion sieve is β-H₂Ti. 0.99 Si 0.01 O3, β-H2Ti 0.98 Si 0.02 O3, β-H2Ti 0.97 Si 0.03 O3, β-H2Ti 0.96 Si 0.04 O3, β-H2Ti 0.95 Si 0.05 O3, β-H2Ti 0.94 Si 0.06 O3, β-H2Ti0.93 Si 0.07 O3, β-H2Ti 0.92 Si 0.08 O3, β-H2Ti 0.91 Si 0.09 O3 or β-H2Ti 0.9 Si 0.1 O3.
[0052] During the doping process, the Si doping amount will not exceed 10% because excessive doping will destroy the structure of the titanium-based adsorbent, thereby leading to a decrease in adsorption capacity.
[0053] Furthermore, the silicon-doped titanium-based lithium-ion sieve has an adsorption capacity of 22-25 mg / g and a titanium loss of 0.10-0.15%.
[0054] Preferably, the specific surface area is 14.3-15 m². 2 / g.
[0055] In specific implementation, the adsorption capacity of silicon-doped titanium-based lithium-ion sieves can be, for example, 22 mg / g, 23 mg / g, 24 mg / g, or 25 mg / g; and the titanium dissolution rate can be, for example, 0.10%, 0.11%, 0.12%, 0.13%, 0.14%, or 0.15%.
[0056] In practical implementation, the specific surface area of silicon-doped titanium-based lithium-ion sieves can be, for example, 14.5 m². 2 / g, 14.6m 2 / g, 14.7m 2 / g, 14.8m 2 / g, 14.9m 2 / g or 15m 2 / g.
[0057] A second aspect of the present invention provides a method for preparing the silicon-doped titanium-based lithium-ion sieve, comprising the following steps:
[0058] A. Mix and grind metatitanic acid and metasilicic acid, and then calcine to obtain a blend containing amorphous TiO2 and amorphous SiO2;
[0059] B. After mixing the lithium source and the blend, deionized water is added and the mixture is pulped to obtain a slurry. The slurry is then microwave-dried and pulverized to obtain a powdered material.
[0060] C. The powdered material is sintered at high temperature to obtain a silicon-doped titanium-based lithium-ion sieve precursor.
[0061] D. The titanium-based lithium-ion sieve precursor is activated in hydrochloric acid solution. After activation, the material is separated into solid and liquid phases, dried and pulverized to obtain the silicon-doped titanium-based lithium-ion sieve.
[0062] The present invention provides a method for preparing silicon-doped titanium-based lithium-ion sieves by introducing silicon as an additive into the raw materials of metatitanic acid and lithium source, thereby controlling the crystal growth rate and improving crystal defects, and obtaining a small-particle-size doped titanium-based lithium-ion sieve precursor β-Li₂Ti. 1-x Si x O3 solves the technical problem of over-burning and caking in titanium-based lithium-ion sieve precursors. This preparation method is continuous, highly mechanized, and has strong controllability of process nodes, making it suitable for large-scale industrial production.
[0063] Specifically, in step A, due to the high chemical reactivity of metatitanic acid and metasilicic acid, their reaction with the lithium source at high temperatures is too rapid and uncontrollable, leading to a large number of lattice defects in the generated β-Li2TiO3, affecting subsequent lithium extraction performance. First, the mixed metatitanic acid and metasilicic acid are calcined to obtain a blend of amorphous TiO2 and SiO2. Since the chemical reactivity of the blend of amorphous TiO2 and SiO2 is lower than that of metatitanic acid and metasilicic acid, the direct high-temperature calcination reaction between metatitanic acid and metasilicic acid and lithium carbonate can be avoided, preventing the excessively rapid reaction rate that leads to a large number of crystal defects, thus solving the problem of crystal defects during high-temperature calcination.
[0064] Because silicon atoms have an electronegativity of 1.9, titanium atoms have an electronegativity of 1.5, and oxygen atoms have an electronegativity of 3.4, the Si-O bond formed by silicon and oxygen atoms is stronger than the Ti-O bond formed by titanium and oxygen atoms. Therefore, it is less prone to breakage and can better improve the performance of titanium-based lithium-ion sieves β-H₂Ti. 1-x Si x The improved acid resistance and service life of O3 solve the problems of low acid resistance and high titanium dissolution of titanium-based lithium ion sieve β-H2TiO3.
[0065] Furthermore, in the lithium source, the metatitanic acid and the metasilicic acid, the molar ratio of Li, Ti and Si is 2.0-2.3:0.9-0.99:0.01-0.1.
[0066] Typical, but not limiting, molar ratios of Li, Ti, and Si can be, for example, 2.0:0.9:0.1, 2.1:0.9:0.1, 2.2:0.9:0.1, 2.3:0.9:0.1, 2.0:0.95:0.05, 2.1:0.95:0.05, 2.2:0.95:0.05, 2.3:0.95:0.05, 2.0:0.99:0.01, 2.1:0.99:0.01, 2.2:0.99:0.01, or 2.3:0.99:0.01.
[0067] Furthermore, in step A, the grinding time is 0.5-2 hours.
[0068] Typically, but not limitingly, the grinding time can be, for example, 0.5h, 1h, 1.5h or 2h.
[0069] Preferably, in step A, the calcination temperature is 400-600℃ and the time is 2-5 hours.
[0070] In the specific roasting process, if the temperature is below 400℃ and the time is less than 2 hours, the dehydration of metatitanic acid will be incomplete; if the temperature is above 600℃ and the time is greater than 5 hours, the resulting titanium dioxide particles will have a large size and a small specific surface area.
[0071] Typical, but not limiting, the roasting temperature can be, for example, 400°C, 450°C, 500°C, 550°C, or 600°C; the time can be, for example, 2h, 3h, 4h, or 5h.
[0072] Preferably, in step A, the heating rate during roasting is 2-6°C / min.
[0073] Typical, but not limiting, heating rates for calcination can be, for example, 2°C / min, 3°C / min, 4°C / min, 5°C / min, or 6°C / min.
[0074] Furthermore, in step B, the amount of deionized water added is 80-120% of the mass of the lithium source and the blend.
[0075] Preferably, in step B, the pulping time is 1-2 hours.
[0076] Preferably, in step B, the particle size of the powdered material is 50-100 mesh.
[0077] Furthermore, in step C, the high-temperature sintering temperature is 800-950℃, and the time is 3-6 hours.
[0078] In the specific sintering process, if the temperature is below 800℃ and the time is less than 3 hours, the ion selectivity will be low; if the temperature is above 950℃ and the time is greater than 6 hours, the adsorbent will sinter and the adsorption capacity will be too low.
[0079] Typical, but not limiting, high-temperature sintering temperatures can be, for example, 800°C, 830°C, 860°C, 890°C, 920°C, or 950°C; and times can be, for example, 3h, 4h, 5h, or 6h.
[0080] Preferably, in step C, the heating rate of the high-temperature sintering is 3-8℃ / min.
[0081] Typical, but not limiting, heating rates for high-temperature sintering can be, for example, 3°C / min, 4°C / min, 5°C / min, 6°C / min, 7°C / min, or 8°C / min.
[0082] Further, in step D, the concentration of the hydrochloric acid solution is 0.1-1 mol / L.
[0083] Furthermore, in step D, the activation temperature is 40-60°C.
[0084] Preferably, in step D, the hydrochloric acid solution is changed every 4-6 hours during the activation process, and the activation process is repeated 2-4 times, which is beneficial to increasing the yield of silicon-doped titanium-based lithium-ion sieves.
[0085] A third aspect of the present invention provides the application of the silicon-doped titanium-based lithium-ion sieve as a lithium extraction adsorbent in the production of lithium salts.
[0086] The silicon-doped titanium-based lithium-ion sieve provided by this invention serves as a lithium extraction adsorbent, offering a better adsorbent for lithium salt production, improving lithium salt production efficiency, and promoting the development of downstream industries.
[0087] The present invention is further illustrated below with specific embodiments and comparative examples. However, it should be understood that these embodiments are merely for illustrative purposes and should not be construed as limiting the invention in any way. Unless otherwise specified, the raw materials used in the embodiments and comparative examples of the present invention were carried out under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.
[0088] Example 1
[0089] This embodiment provides a silicon-doped titanium-based lithium-ion sieve, and the specific preparation method is as follows:
[0090] 1. Weigh out lithium carbonate, metatitanic acid, and metasilicic acid samples according to the molar ratio of Li:Ti:Si of 2:0.95:0.05 and place them in beakers for later use.
[0091] 2. Place the weighed metatitanic acid and metasilicic acid in a mortar, add alcohol to moisten them and grind for 1 hour. Place the mixed metatitanic acid and metasilicic acid mixture in a muffle furnace for calcination. The heating rate is 3℃ / min, the calcination temperature is 400℃, and the calcination time is 3 hours to obtain a blend of amorphous TiO2 and amorphous SiO2.
[0092] 3. The prepared blend of amorphous TiO2 and amorphous SiO2 was mixed with lithium carbonate in a beaker. Deionized water was added to the beaker, with the mass of deionized water being 100% of the total solid mass. The mixture was mechanically stirred and water-pulverized for 2 hours to ensure uniform mixing of the raw materials. After uniform mixing, the slurry was dried using a microwave dryer. The dried lumps were then pulverized using a pulverizer and passed through a 100-mesh sieve for later use.
[0093] 4. The sieved material is calcined in a muffle furnace at a heating rate of 5℃ / min and a constant temperature of 800℃ for 3 hours to obtain the Si-doped titanium-based lithium-ion sieve precursor β-Li2Ti. 1-x Si x O3.
[0094] 5. Using Si-doped titanium-based lithium-ion sieve precursor β-Li₂Ti 1-x Si x O3 was activated in a 0.1 mol / L hydrochloric acid solution at a water bath temperature of 40°C. The hydrochloric acid solution was changed every 5 hours, and the activation process was repeated three times. The activated powder was centrifuged, the precipitate was removed and dried in a 60°C oven, and then pulverized to obtain silicon-doped titanium-based lithium-ion sieve β-H2Ti. 1- x Si x O3 powder.
[0095] Testing revealed that this silicon-doped titanium-based lithium-ion sieve, β-H₂Ti, 1-x Si x The chemical formula of O3 powder is β-H2Ti. 0.95 Si 0.05 O3.
[0096] Example 2
[0097] This embodiment provides a silicon-doped titanium-based lithium-ion sieve, and the specific preparation method is as follows:
[0098] 1. Weigh out lithium carbonate, metatitanic acid, and metasilicic acid samples according to the molar ratio of Li:Ti:Si of 2:0.97:0.03 and place them in beakers for later use.
[0099] 2. Same as the steps in Example 1.
[0100] 3. Same as the steps in Example 1.
[0101] 4. The sieved material is calcined in a muffle furnace at a heating rate of 5℃ / min and a constant temperature of 950℃ for 3 hours to obtain the Si-doped titanium-based lithium-ion sieve precursor β-Li2Ti. 1-x Si x O3.
[0102] 5. Same as the steps in Example 1.
[0103] Testing revealed that this silicon-doped titanium-based lithium-ion sieve, β-H₂Ti, 1-x Si x The chemical formula of O3 powder is β-H2Ti. 0.97 Si 0.03 O3.
[0104] Example 3
[0105] This embodiment provides a silicon-doped titanium-based lithium-ion sieve, and the specific preparation method is as follows:
[0106] 1. Weigh out lithium carbonate, metatitanic acid, and metasilicic acid samples according to the molar ratio of Li:Ti:Si of 2:0.9:0.1 and place them in beakers for later use.
[0107] 2. Same as the steps in Example 1.
[0108] 3. Same as the steps in Example 1.
[0109] 4. Same as the steps in Example 1.
[0110] 5. Same as the steps in Example 1.
[0111] Testing revealed that this silicon-doped titanium-based lithium-ion sieve, β-H₂Ti, 1-x Si x The chemical formula of O3 powder is β-H2Ti. 0.9 Si 0.1 O3.
[0112] Example 4
[0113] This embodiment provides a silicon-doped titanium-based lithium-ion sieve, and the specific preparation method is as follows:
[0114] 1. Weigh out lithium carbonate, metatitanic acid, and metasilicic acid samples according to the molar ratio of Li:Ti:Si of 2:0.99:0.01 and place them in beakers for later use.
[0115] 2. Same as the steps in Example 1.
[0116] 3. Same as the steps in Example 1.
[0117] 4. Same as the steps in Example 1.
[0118] 5. Same as the steps in Example 1.
[0119] Testing revealed that this silicon-doped titanium-based lithium-ion sieve, β-H₂Ti, 1-x Si x The chemical formula of O3 powder is β-H2Ti. 0.99 Si 0.01 O3.
[0120] Example 5
[0121] This embodiment provides a silicon-doped titanium-based lithium-ion sieve, and the specific preparation method is as follows:
[0122] 1. Same as the steps in Example 1.
[0123] 2. Place the weighed metatitanic acid and metasilicic acid in a mortar, add alcohol to moisten them and grind for 2 hours. Place the mixed metatitanic acid and metasilicic acid mixture in a muffle furnace for calcination. The heating rate is 3℃ / min, the calcination temperature is 500℃ and the calcination time is 2 hours to obtain a blend of amorphous TiO2 and amorphous SiO2.
[0124] 3. The prepared blend of amorphous TiO2 and amorphous SiO2 was mixed with lithium carbonate in a beaker. Deionized water was added to the beaker, with the mass of deionized water being 100% of the total solid mass. The mixture was mechanically stirred and water-pulverized for 2 hours to ensure uniform mixing of the raw materials. After uniform mixing, the slurry was dried using a microwave dryer. The dried lumps were then pulverized using a pulverizer and passed through a 100-mesh sieve for later use.
[0125] 4. The sieved material is calcined in a muffle furnace at a heating rate of 5℃ / min and a constant temperature of 950℃ for 3 hours to obtain the Si-doped titanium-based lithium-ion sieve precursor β-Li2Ti. 1-x Si x O3.
[0126] 5. Using Si-doped titanium-based lithium-ion sieve precursor β-Li₂Ti 1-x Si xO3 was activated in a 0.1 mol / L hydrochloric acid solution at a water bath temperature of 60°C. The hydrochloric acid solution was changed every 4 hours, and the activation process was repeated 4 times. The activated powder was centrifuged, the precipitate was removed, dried in a 60°C oven, and then pulverized to obtain silicon-doped titanium-based lithium-ion sieve β-H2Ti. 1- x Si x O3 powder.
[0127] Testing revealed that this silicon-doped titanium-based lithium-ion sieve, β-H₂Ti, 1-x Si x The chemical formula of O3 powder is β-H2Ti. 0.95 Si 0.05 O3.
[0128] Example 6
[0129] This embodiment provides a silicon-doped titanium-based lithium-ion sieve, and the specific preparation method is as follows:
[0130] 1. Same as the steps in Example 1.
[0131] 2. Place the weighed metatitanic acid and metasilicic acid in a mortar, moisten with alcohol, and grind for 0.5 h. Place the mixed metatitanic acid and metasilicic acid mixture in a muffle furnace for calcination. The heating rate is 3℃ / min, the calcination temperature is 600℃, and the calcination time is 5 h to obtain a blend of amorphous TiO2 and amorphous SiO2.
[0132] 3. The prepared blend of amorphous TiO2 and amorphous SiO2 was mixed with lithium carbonate in a beaker. Deionized water was added to the beaker, with the mass of deionized water being 100% of the total solid mass. The mixture was mechanically stirred and water-pulverized for 1 hour to ensure uniform mixing of the raw materials. After uniform mixing, the slurry was dried using a microwave dryer. The dried lumps were then pulverized using a pulverizer and passed through a 100-mesh sieve for later use.
[0133] 4. The sieved material is calcined in a muffle furnace at a heating rate of 5℃ / min and a constant temperature of 800℃ for 6 hours to obtain the Si-doped titanium-based lithium-ion sieve precursor β-Li2Ti. 1-x Si x O3.
[0134] 5. Using Si-doped titanium-based lithium-ion sieve precursor β-Li₂Ti 1-x Si xO3 was activated in a 0.1 mol / L hydrochloric acid solution at a water bath temperature of 60°C. The hydrochloric acid solution was changed every 6 hours, and the activation process was repeated twice. The activated powder was centrifuged, the precipitate was dried in a 60°C oven, and then pulverized to obtain silicon-doped titanium-based lithium-ion sieve β-H2Ti. 1- x Si x O3 powder.
[0135] Testing revealed that this silicon-doped titanium-based lithium-ion sieve, β-H₂Ti, 1-x Si x The chemical formula of O3 powder is β-H2Ti. 0.95 Si 0.05 O3.
[0136] Comparative Example 1
[0137] This comparative example provides a titanium-based lithium-ion sieve, and the specific preparation method is as follows:
[0138] 1. Metatitanic acid was placed in a muffle furnace for calcination at a heating rate of 3℃ / min, a calcination temperature of 400℃, and a calcination time of 3h to obtain amorphous TiO2.
[0139] 2. The prepared amorphous TiO2 and lithium carbonate were mixed with water at a molar ratio of 2.1:1.0 for 2 hours. After the slurry was mixed evenly, it was dried by microwave drying. The dried block material was then crushed by a pulverizer and passed through a 100-mesh sieve for later use.
[0140] 3. The sieved material is calcined in a muffle furnace at a heating rate of 5℃ / min and a constant temperature of 800℃ for 3 hours to obtain the titanium-based lithium ion sieve precursor β-Li2TiO3.
[0141] 4. The titanium-based lithium-ion sieve precursor β-Li₂TiO₃ was activated in a 0.1 mol / L hydrochloric acid solution, with the water bath temperature controlled at 40℃. The hydrochloric acid solution was changed every 5 hours, and the activation step was repeated 3 times. The activated powder was centrifuged, the precipitate was removed and dried in a 60℃ oven, and then pulverized to obtain the titanium-based lithium-ion sieve β-H₂TiO₃ powder.
[0142] Comparative Example 2
[0143] This comparative example provides a titanium-based lithium-ion sieve, and the specific preparation method is as follows:
[0144] 1. Follow the same steps as in Comparative Example 1.
[0145] 2. Follow the same steps as in Comparative Example 1.
[0146] 3. The sieved material is calcined in a muffle furnace at a heating rate of 5℃ / min and a constant temperature of 950℃ for 3 hours to obtain the titanium-based lithium ion sieve precursor β-Li2TiO3.
[0147] 4. Follow the same steps as in Comparative Example 1.
[0148] Test Example 1
[0149] The silicon-doped titanium-based lithium-ion sieve β-H2Ti obtained in Example 1 0.95 Si 0.05 XRD was performed on O3 and the titanium-based lithium-ion sieve β-H2TiO3 obtained in Comparative Example 1, and the XRD patterns are shown below. Figure 1 As shown.
[0150] from Figure 1 The XRD pattern shows that β-H2Ti 0.95 Si 0.05 The characteristic peaks of O3 all match the characteristic peaks of β-H2TiO3, and no other impurity peaks appear. After doping with Si, the characteristic peaks shift to a lower angle as a whole, indicating that doping with a small amount of Si can be fully integrated into the lithium titanate lattice.
[0151] right Figure 1 The (002) crystal plane in the XRD pattern is magnified to obtain Figure 2 A magnified view of the (002) crystal plane. From Figure 2 It can be seen that the main diffraction peak (002) shifts significantly to a lower angle, indicating that the interplanar spacing increases after Si doping, further demonstrating the success of Si doping.
[0152] Test Example 2
[0153] The silicon-doped titanium-based lithium-ion sieve β-H2Ti obtained in Example 1 0.95 Si 0.05 Scanning electron microscopy (SEM) was performed on O3 and the titanium-based lithium-ion sieve β-H2TiO3 obtained in Comparative Example 1. The corresponding SEM images are as follows: Figure 3 and Figure 4 As shown.
[0154] from Figure 3 and Figure 4 It can be seen that both materials are composed of particle packing, and the morphology of titanium-based lithium-ion sieves does not change significantly whether or not they are doped with Si.
[0155] Test Example 3
[0156] The silicon-doped titanium-based lithium-ion sieve β-H2Ti obtained in Example 2 0.97 Si 0.03 XRD was performed on O3 and the titanium-based lithium-ion sieve β-H2TiO3 obtained in Comparative Example 2, and the XRD spectra are shown below. Figure 5 As shown.
[0157] from Figure 5 The XRD pattern shows that β-H2Ti 0.97 Si 0.03 The characteristic peaks of O3 all match the characteristic peaks of β-H2TiO3, and no other impurity peaks appear. After doping with Si, the characteristic peaks shift to a lower angle as a whole, indicating that doping with a small amount of Si can be fully integrated into the lithium titanate lattice.
[0158] right Figure 5 The (002) crystal plane in the XRD pattern is magnified to obtain Figure 6 A magnified view of the (002) crystal plane. From Figure 6 It can be seen that the main diffraction peak (002) shifts significantly to a lower angle, indicating that the interplanar spacing increases after Si doping, further demonstrating the success of Si doping.
[0159] Test Example 4
[0160] The silicon-doped titanium-based lithium-ion sieve β-H2Ti obtained in Example 2 0.97 Si 0.03 Scanning electron microscopy (SEM) was performed on O3 and the titanium-based lithium-ion sieve β-H2TiO3 obtained in Comparative Example 2. The corresponding SEM images are as follows: Figure 7 and Figure 8 As shown.
[0161] from Figure 7 and Figure 8 It can be seen that both materials are composed of particle packing, and the morphology of titanium-based lithium-ion sieves does not change significantly whether or not they are doped with Si.
[0162] Test Example 5
[0163] 1g of lithium-ion sieves from Examples 1-6 and Comparative Examples 1-2 were placed into 200mL of prepared simulated salt lake brine and magnetically stirred for 3 hours at room temperature for adsorption. The solution was then drawn up with a syringe, and the powder was filtered out. The resulting water sample was then subjected to Li... + Concentration was measured using an inductively coupled plasma atomic emission spectrometer (OPtima 8000). The mass adsorption capacity Q was calculated.
[0164] The solution after adsorption for 3 hours was filtered, and the powder was rinsed repeatedly with pure water until the TDS of the filtered solution was <20 mg / L. The filtered powder was then dried in a 60℃ oven and ground. 0.5 g of the ground powder was added to 100 mL of 0.1 mol / L hydrochloric acid solution, and then magnetically stirred in a 40℃ water bath for 1 hour. The water sample obtained after filtering out the powder was analyzed using an inductively coupled plasma atomic emission spectrometer (OPtima 8000). + Na+ The concentrations of C and C are denoted as C. Li C Na Calculate Li + / Na + .
[0165] The results are shown in Table 1 below.
[0166] Table 1
[0167]
[0168] As can be seen from Table 1, the titanium-based lithium-ion sieves obtained after high-temperature calcination in Comparative Examples 1 and 2 are yellowish, hardened, and lumpy. However, the sieves in Examples 1-6 are white and soft.
[0169] The specific surface area of Comparative Examples 1-2 is only 6.78-8.76 m². 2 The adsorption capacity is only 4.5-5.6 mg / g, the Li / Na ratio is 23.3-24, and the titanium dissolution loss is 0.25-0.34%. However, the silicon-doped titanium-based lithium-ion sieves in Examples 1-6 have a specific surface area of 14.3-15 m² / g. 2 The specific surface area of the silicon-doped lithium ion sieve is significantly higher than that of the undoped silicon sieve, with an adsorption capacity of 22-25 mg / g, a Li / Na ratio of 24-26, and a titanium dissolution loss of only 0.11-0.15%. This indicates that the lithium ion sieve prepared under high-temperature conditions after silicon doping exhibits both high adsorption capacity and high selectivity.
[0170] Test Example 6
[0171] The preparation method of Example 1 was repeated 20 times to obtain 20 batches of silicon-doped titanium-based lithium-ion sieves. The adsorption capacity and Li / Na ratio of these 20 batches of silicon-doped titanium-based lithium-ion sieves were tested according to the method in Test Example 5, and the obtained data were plotted. Figure 9 and Figure 10 .
[0172] from Figure 9 It can be seen that the Li in silicon-doped titanium-based lithium-ion sieves + The adsorption capacity was very stable, with good repeatability, and the adsorption performance remained at around 25 mg / g. Figure 10 It can be seen that the Li / Na selectivity of silicon-doped titanium-based lithium-ion sieves is also relatively stable, consistently around 24.
[0173] Finally, it should be noted that the above-described embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and not to limit it. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the technical scope disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.
Claims
1. A method for preparing a silicon-doped titanium-based lithium-ion sieve, characterized in that, Includes the following steps: A. Mix and grind metatitanic acid and metasilicic acid, and then calcine to obtain a blend containing amorphous TiO2 and amorphous SiO2; B. After mixing the lithium source and the blend, deionized water is added and the mixture is pulped to obtain a slurry. The slurry is then microwave-dried and pulverized to obtain a powdered material. C. The powdered material is sintered at high temperature to obtain a silicon-doped titanium-based lithium-ion sieve precursor. D. The titanium-based lithium-ion sieve precursor is activated in hydrochloric acid solution. After activation, the material is separated into solid and liquid phases, dried and pulverized to obtain the silicon-doped titanium-based lithium-ion sieve. The silicon-doped titanium-based lithium-ion sieve has the chemical formula β-H₂Ti. 1-x Si x O3; where 0 < x ≤ 0.
1.
2. The preparation method according to claim 1, characterized in that, The silicon-doped titanium-based lithium-ion sieve has an adsorption capacity of 22-25 mg / g and a titanium loss of 0.10-0.15%.
3. The preparation method according to claim 1, characterized in that, The silicon-doped titanium-based lithium-ion sieve has a specific surface area of 14.3-15 m². 2 / g.
4. The preparation method according to claim 1, characterized in that, In the lithium source, the metatitanic acid and the metasilicic acid, the molar ratio of Li, Ti and Si is 2.0-2.3:0.9-0.99:0.01-0.
1.
5. The preparation method according to claim 1, characterized in that, In step A, the grinding time is 0.5-2 hours.
6. The preparation method according to claim 1, characterized in that, In step A, the roasting temperature is 400-600℃ and the time is 2-5 hours.
7. The preparation method according to claim 1, characterized in that, In step A, the heating rate during roasting is 2-6℃ / min.
8. The preparation method according to claim 1, characterized in that, In step B, the amount of deionized water added is 80-120% of the mass of the lithium source and the blend.
9. The preparation method according to claim 1, characterized in that, In step B, the pulping time is 1-2 hours.
10. The preparation method according to claim 1, characterized in that, In step B, the particle size of the powdered material is 50-100 mesh.
11. The preparation method according to claim 1, characterized in that, In step C, the high-temperature sintering temperature is 800-950℃ and the time is 3-6 hours.
12. The preparation method according to claim 1, characterized in that, In step C, the heating rate of the high-temperature sintering is 3-8℃ / min.
13. The preparation method according to claim 1, characterized in that, In step D, the concentration of the hydrochloric acid solution is 0.1-1 mol / L.
14. The preparation method according to any one of claims 1-13, characterized in that, In step D, the activation temperature is 40-60℃.
15. The preparation method according to any one of claims 1-13, characterized in that, In step D, the hydrochloric acid solution is changed every 4-6 hours during the activation process, and the activation process is repeated 2-4 times.
16. The application of a silicon-doped titanium-based lithium-ion sieve prepared by the preparation method according to any one of claims 1-15 as a lithium extraction adsorbent in the production of lithium salts.