Coated modified anhydrous lithium hydroxide and a method for preparing the same

Abstract

The application relates to the technical field of lithium hydroxide, and particularly discloses coated modified anhydrous lithium hydroxide and a preparation method thereof. The coated modified anhydrous lithium hydroxide is prepared by the following steps: weighing an internal matrix and an external coating modifier; the internal matrix is anhydrous lithium hydroxide, and the external coating modifier is one of polyaspartic acid, polyacrylamide or polyacrylic acid; the external coating modifier is dissolved in deionized water to prepare a coating modifier solution; the matrix is coated with the coating modifier solution to obtain wet coated modified anhydrous lithium hydroxide; and the wet coated modified anhydrous lithium hydroxide is dried to obtain the coated modified anhydrous lithium hydroxide. The coated modified anhydrous lithium hydroxide has a physical coating layer on the surface of the anhydrous lithium hydroxide, the operation is simple, the particle hardness can be increased, the dust diffusion caused by collision and friction on the particle surface can be effectively reduced, and the dust raising problem is solved. The coated modified anhydrous lithium hydroxide can guarantee the effective absorption agent content and absorption performance, improve the use safety of the lithium hydroxide absorption agent, and meet the requirements of products of the anhydrous lithium hydroxide in multiple fields.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium hydroxide, in particular to a coated modified anhydrous lithium hydroxide and a preparation method thereof. BACKGROUND

[0002] Lithium hydroxide is a highly efficient carbon dioxide absorbent, which has the characteristics of fast absorption speed, large adsorption capacity per unit mass, and easy handling of reaction products. Since lithium hydroxide is a strong alkaline substance, it can easily produce corrosive dust during use, causing irritation to the human body. Therefore, in order to improve and solve the dust problem of lithium hydroxide products, the lithium hydroxide is modified by the skilled in the art. The invention patent CN102020294B discloses a dust-free monohydrate lithium hydroxide and a preparation method thereof, which provides a dust-free monohydrate lithium hydroxide wet product without drying. Since the water content is large, there is no dust during use, but the product will cake after a long time, and a anti-caking agent needs to be wrapped on the surface of lithium hydroxide to prevent caking during long-term storage.

[0003] The invention patents CN104163442B, CN102786069B, etc. wrap a surfactant on the surface of monohydrate lithium hydroxide to ensure that there is no dust and irritating odor during use, but monohydrate lithium hydroxide contains crystal water, which reduces the content of effective absorbent lithium hydroxide, and the content of lithium hydroxide can only reach 55-57%, and the specific surface area of lithium hydroxide is also reduced.

[0004] The invention patents CN112216834B, CN112299452A, etc. spray liquid alkanes, alkane derivatives, etc. on the surface of lithium hydroxide, and dry to obtain anhydrous lithium hydroxide. Although this method can reduce irritating dust, the boiling point of alkanes and other substances is low, and the absorption process may release heat, which may volatilize during product use, and the gas permeability is poor, which reduces the absorption performance and quality of lithium hydroxide.

[0005] In summary, the existing lithium hydroxide has the problems of dust flying and strong irritation during use, and the modified product has the problems of high water content, low content of effective absorbent, volatilization of modifier, and poor gas permeability. SUMMARY

[0006] In view of the problems in the prior art, one object of the present application is to provide a preparation method of coated modified anhydrous lithium hydroxide for preparing the coated modified anhydrous lithium hydroxide of the present application. A physical coating layer is coated on the surface of anhydrous lithium hydroxide, which is simple to operate, can increase the hardness of the particles, and effectively reduce the diffusion of dust generated by collision and friction on the surface of the particles, thereby solving the problem of dust flying.

[0007] The second object of the present application is to provide a coated modified anhydrous lithium hydroxide. It can increase the particle hardness, solve the dust problem, ensure the effective absorbent content and absorption performance, improve the use safety of lithium hydroxide absorbent, expand the application range, improve the use performance, and meet the requirements of anhydrous lithium hydroxide products in multiple fields.

[0008] The first technical solution adopted by the present application is a preparation method of coated modified anhydrous lithium hydroxide, comprising the following steps:

[0009] Step one: weigh the internal matrix and the external coating modifier; the internal matrix is anhydrous lithium hydroxide, and the external coating modifier is one of polyaspartic acid, polyacrylamide or polyacrylic acid;

[0010] Step two: dissolve the external coating modifier in deionized water to obtain a coating modifier solution;

[0011] Step three: use the coating modifier solution to coat the internal matrix to obtain wet coated modified anhydrous lithium hydroxide;

[0012] Step four: dry the wet coated modified anhydrous lithium hydroxide to obtain coated modified anhydrous lithium hydroxide.

[0013] Preferably, the anhydrous lithium hydroxide in step one is in the form of particles.

[0014] Preferably, the molecular weight of the polyaspartic acid is in the range of 2000-20000; the molecular weight of the polyacrylamide is in the range of 20000-100000; and the molecular weight of the polyacrylic acid is in the range of 500-5000.

[0015] Preferably, the mass concentration of the external coating modifier in the coating modifier solution in step two is 0.1%~8%.

[0016] Preferably, the mass ratio of the external coating modifier to the internal matrix is 0.1%~2.0%.

[0017] Preferably, the coating method in step three comprises: adding the internal matrix to the coating modifier solution;

[0018] Or, the coating modifier solution is uniformly sprayed on the surface of the internal matrix.

[0019] Preferably, the drying conditions in step four are: temperature 90~150℃, time 4~12h.

[0020] The second technical solution adopted by the present application is: a coated modified anhydrous lithium hydroxide, comprising an internal base and an external coating modifier; the mass ratio of the external coating modifier to the internal base is 0.1% to 2.0%;

[0021] The internal base is anhydrous lithium hydroxide.

[0022] The external coating modifier is one of polyaspartic acid, polyacrylamide or polyacrylic acid.

[0023] Preferably, the molecular weight of the polyaspartic acid is in the range of 2000 to 20000; the molecular weight of the polyacrylamide is in the range of 20000 to 100000; and the molecular weight of the polyacrylic acid is in the range of 500 to 5000.

[0024] Preferably, the molecular weight of the polyaspartic acid is one of 4000, 6000 to 8000 and 10000 to 12000; the molecular weight of the polyacrylamide is in the range of 20000 to 100000; and the molecular weight of the polyacrylic acid is one of 1000 and 3000.

[0025] The beneficial effects of the above technical solution are:

[0026] (1) The coated modified anhydrous lithium hydroxide provided by the present application has no crystalline water in the molecule, is not easy to adsorb on the pipe wall of the device, and is not easy to caking and failure. It can reduce the replacement and cleaning frequency, save raw materials, and reduce costs. The coating modifier effectively reduces the dust diffusion generated by the collision and friction of the particle surface, solves the dust problem. The content of the modifier is low, the content of lithium hydroxide is high, the specific surface area is large, the absorption performance is good, and the loading capacity is low. The coated modified anhydrous lithium hydroxide can basically maintain the carbon dioxide absorption efficiency of the uncoated anhydrous lithium hydroxide, and does not affect the use performance of the product.

[0027] (2) The preparation method of the coated modified anhydrous lithium hydroxide provided by the present application coats a layer of physical coating layer on the surface of the anhydrous lithium hydroxide, which is simple to operate, can increase the hardness of the particles, effectively reduces the dust diffusion generated by the collision and friction of the particle surface, solves the dust problem, protects the health of the user, and the modifier used in the present application contains active group structures such as amino and carboxyl groups, has strong chelation, dispersion, adsorption and other effects, and is a good coating material. The modifier material has porosity and strong gas permeability, and will not affect the absorption performance of lithium hydroxide. At the same time, the boiling point of the modifier is high, green, non-toxic and harmless, will not volatilize in the product use process, and avoid harm to human health. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 The carbon dioxide static absorption curve of the coated modified anhydrous lithium hydroxide provided for an embodiment 1 of the present application. DETAILED DESCRIPTION

[0029] Further specific embodiments of the present application will be described in further detail below. It should be apparent that the examples described are only a part of the embodiments of the present application and are not exhaustive. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0030] The terms "first", "second", and the like, if any, in the description and the claims are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the use of such terms is not intended to limit the scope of the embodiments described herein, and the embodiments described herein are not limited to the order in which the steps are presented. Further, the terms "comprise" and "comprising" and any variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, system, product, or apparatus that comprises a list of steps or elements not necessarily limited to those listed, but can include additional steps or elements not expressly listed or inherent to such process, method, product, or apparatus.

[0031] It should be understood that the term "and / or" used herein is only a description of the association relationship between the associated objects, which means that there can be three relationships, for example, A and / or B, which means that there are three cases of A alone, A and B together, and B alone. In addition, the character " / " herein generally represents an "or" relationship between the front and rear associated objects.

[0032] The polyaspartic acid with a molecular weight of 4000 and 6000-8000 is respectively denoted as polyaspartic acid 4000 and polyaspartic acid 6000-8000; the polyacrylamide with a molecular weight of 20000-100000 is denoted as polyacrylamide 20000-100000; the polyacrylic acid with a molecular weight of 1000 and 3000 is respectively denoted as polyacrylic acid 1000 and polyacrylic acid 3000.

[0033] Example 1

[0034] A coated modified anhydrous lithium hydroxide of the present application includes an anhydrous lithium hydroxide base and an external coating modifier coated on the surface of the anhydrous lithium hydroxide base, and the material of the external coating modifier is polyaspartic acid 4000.

[0035] The preparation method of the coated modified anhydrous lithium hydroxide of the present embodiment includes the following steps:

[0036] (1) Dissolve polyaspartic acid 4000 in deionized water, manually stir until uniform, the stirring time is 3 min, and prepare a solution of 200 g with a concentration of 3%;

[0037] (2) take 50 g of anhydrous lithium hydroxide particles, pour into the solution obtained in step (1), shake the container to mix for 10 s, then filter to obtain wet particles with the surface attached modifier;

[0038] (3) put the wet anhydrous lithium hydroxide particles obtained in step (2) into a drying oven (temperature is 140℃, drying time is 12 h) to obtain the coated modified anhydrous lithium hydroxide.

[0039] The particle hardness test shows that the average hardness of the coated modified anhydrous lithium hydroxide particles prepared in this embodiment is 20.81 N; the carbon dioxide static absorption performance test shows that the carbon dioxide static absorption rate after 20 minutes is 65.4%; and there is no dust phenomenon in the experiment.

[0040] Example 2

[0041] A coated modified anhydrous lithium hydroxide of the present application, an anhydrous lithium hydroxide base and a coated modifier coated on the surface of the anhydrous lithium hydroxide base, the coated modifier material is polyaspartic acid 4000.

[0042] The preparation method of the coated modified anhydrous lithium hydroxide of this embodiment includes the following steps:

[0043] (1) dissolve polyaspartic acid 4000 in deionized water, manually stir until uniform, the stirring time is 3 min, and prepare a solution of 200 g with a concentration of 4%;

[0044] (2) take 50 g of anhydrous lithium hydroxide particles, pour into the solution obtained in step (1), shake the container to mix for 10 s, then filter to obtain wet particles with the surface attached modifier;

[0045] (3) put the wet anhydrous lithium hydroxide particles obtained in step (2) into a drying oven (temperature is 140℃, drying time is 12 h) to obtain the coated modified anhydrous lithium hydroxide.

[0046] The particle hardness test shows that the average hardness of the coated modified anhydrous lithium hydroxide particles prepared in this embodiment is 23.23 N; the carbon dioxide static absorption performance test shows that the carbon dioxide static absorption rate after 20 minutes is 64.9%; and there is no dust phenomenon in the experiment.

[0047] Example 3

[0048] A coated modified anhydrous lithium hydroxide of the present application, an anhydrous lithium hydroxide base and a coated modifier coated on the surface of the anhydrous lithium hydroxide base, the coated modifier material is polyaspartic acid 4000.

[0049] The preparation method of the coated modified anhydrous lithium hydroxide of this embodiment includes the following steps:

[0050] (1) Dissolve polyaspartic acid 4000 in deionized water, manually stir evenly, stirring time is 3 min, configure 200 g solution with concentration of 5%;

[0051] (2) Take 50 g of lithium hydroxide anhydrous particles, pour into the solution obtained in step (1), shake the container to mix for 10 s, then filter to obtain wet particles with surface-attached modifier;

[0052] (3) Put the wet lithium hydroxide anhydrous particles obtained in step (2) into a drying oven (temperature is 140 ℃, drying time is 12 h) to obtain coated modified lithium hydroxide anhydrous.

[0053] The average hardness of the coated modified lithium hydroxide anhydrous particles prepared in this embodiment is 27.63 N through particle hardness test; the carbon dioxide static absorption rate after 20 min is 60.2% through carbon dioxide static absorption performance test; no dust phenomenon occurs in the experiment.

[0054] Example 4

[0055] A coated modified lithium hydroxide anhydrous of the present application, a lithium hydroxide anhydrous matrix and a coated modifier coated on the surface of the lithium hydroxide anhydrous matrix, the coated modifier material is polyaspartic acid 6000-8000.

[0056] The preparation method of the coated modified lithium hydroxide anhydrous of this embodiment comprises the following steps:

[0057] (1) Dissolve polyaspartic acid 6000-8000 in deionized water, manually stir evenly, stirring time is 3 min, configure 200 g solution with concentration of 4%;

[0058] (2) Take 50 g of lithium hydroxide anhydrous particles, pour into the solution obtained in step (1), shake the container to mix for 10 s, then filter to obtain wet particles with surface-attached modifier;

[0059] (3) Put the wet lithium hydroxide anhydrous particles obtained in step (2) into a drying oven (temperature is 140 ℃, drying time is 12 h) to obtain coated modified lithium hydroxide anhydrous.

[0060] The average hardness of the coated modified lithium hydroxide anhydrous particles prepared in this embodiment is 29.52 N through particle hardness test; the carbon dioxide static absorption rate after 20 min is 60.7% through carbon dioxide static absorption performance test; no dust phenomenon occurs in the experiment.

[0061] Example 5

[0062] A coated modified anhydrous lithium hydroxide of the present application, an anhydrous lithium hydroxide base and a coating modifier coated on the surface of the anhydrous lithium hydroxide base, the coating modifier material is polyacrylamide 20000-100000.

[0063] The preparation method of the coated modified anhydrous lithium hydroxide of the present application comprises the following steps:

[0064] (1) Dissolve polyacrylamide 20000-100000 in deionized water, manually stir until uniform, stirring time is 3 min, prepare a solution of 200 g with a concentration of 2%;

[0065] (2) Weigh 50 g of anhydrous lithium hydroxide particles, pour into the solution obtained in step (1), shake the container to mix for 10 s, then filter to obtain wet particles with the surface attached modifier;

[0066] (3) Put the anhydrous lithium hydroxide wet particles obtained in step (2) into a drying oven (temperature is 140℃, drying time is 12 h) to obtain coated modified anhydrous lithium hydroxide.

[0067] The average hardness of the coated modified anhydrous lithium hydroxide particles prepared in this embodiment is 24.97 N through particle hardness test; the carbon dioxide static absorption rate after 20 min is 59.4% through carbon dioxide static absorption performance test; no dust phenomenon occurs during the experiment.

[0068] Example 6

[0069] A coated modified anhydrous lithium hydroxide of the present application, an anhydrous lithium hydroxide base and a coating modifier coated on the surface of the anhydrous lithium hydroxide base, the coating modifier material is polyacrylic acid 3000.

[0070] The preparation method of the coated modified anhydrous lithium hydroxide of the present application comprises the following steps:

[0071] (1) Dissolve polyacrylic acid 3000 in deionized water, manually stir until uniform, stirring time is 3 min, prepare a solution of 200 g with a concentration of 3%;

[0072] (2) Weigh 50 g of anhydrous lithium hydroxide particles, pour into the solution obtained in step (1), shake the container to mix for 10 s, then filter to obtain wet particles with the surface attached modifier;

[0073] (3) Put the anhydrous lithium hydroxide wet particles obtained in step (2) into a drying oven (temperature is 140℃, drying time is 12 h) to obtain coated modified anhydrous lithium hydroxide.

[0074] The average hardness of the coated modified anhydrous lithium hydroxide particles prepared in this example is 28.35 N, as indicated by the particle hardness test; the carbon dioxide static absorption rate after 20 minutes is 59.1%, as indicated by the carbon dioxide static absorption performance test; and no dust is generated during the experiment.

[0075] Example 7

[0076] A coated modified anhydrous lithium hydroxide of the present application, an anhydrous lithium hydroxide base and a coating modifier coated on the surface of the anhydrous lithium hydroxide base, the coating modifier material is polyacrylic acid 1000.

[0077] The preparation method of the coated modified anhydrous lithium hydroxide of this example comprises the following steps:

[0078] (1) Dissolve polyacrylic acid 1000 in deionized water, manually stir until uniform, the stirring time is 3 min, and prepare a solution of 200 g with a concentration of 4%;

[0079] (2) Weigh 50 g of anhydrous lithium hydroxide particles, pour into the solution obtained in step (1), shake the container for 10 s, then filter to obtain wet particles with a surface attached modifier;

[0080] (3) Put the anhydrous lithium hydroxide wet particles obtained in step (2) into a drying oven (temperature is 140℃, drying time is 12 h) to obtain coated modified anhydrous lithium hydroxide.

[0081] The average hardness of the coated modified anhydrous lithium hydroxide particles prepared in this example is 27.7 N, as indicated by the particle hardness test; the carbon dioxide static absorption rate after 20 minutes is 61.7%, as indicated by the carbon dioxide static absorption performance test; and no dust is generated during the experiment.

[0082] Comparative Example

[0083] The preparation method of the anhydrous lithium hydroxide of this comparative example, without a coating modifier, comprises the following steps:

[0084] (1) Weigh 50 g of anhydrous lithium hydroxide particles;

[0085] (2) Put the anhydrous lithium hydroxide particles obtained in step (1) into a drying oven (temperature is 140℃, drying time is 12 h) to obtain anhydrous lithium hydroxide.

[0086] The average hardness of the anhydrous lithium hydroxide particles prepared in this comparative example is 15.42 N, as indicated by the particle hardness test; the carbon dioxide static absorption rate after 20 minutes is 68.3%, as indicated by the carbon dioxide static absorption performance test; and dust is obviously generated during the experiment.

[0087] The experimental results of Examples 1-7 and Comparative Examples, and Figure 1 The carbon dioxide static absorption curve of the coated modified anhydrous lithium hydroxide provided by Example 1 shows that the coated modified anhydrous lithium hydroxide effectively reduces the dust diffusion caused by collision and friction on the surface of the particles, and solves the problem of dust raising. The content of the modifier is low, the content of lithium hydroxide is high, the specific surface area is large, the absorption performance is good, and the loading capacity is low. The coated modified anhydrous lithium hydroxide can basically maintain the carbon dioxide absorption efficiency of uncoated anhydrous lithium hydroxide, and does not affect the performance of the product. The preparation method of the coated modified anhydrous lithium hydroxide provided by the present application is simple to operate, and the modifier used contains active groups such as amino and carboxyl groups, which have strong chelation, dispersion, adsorption and other effects, and is a good coating material. The modifier material has porosity and strong gas permeability, and will not affect the absorption performance of lithium hydroxide. At the same time, the modifier has a high boiling point, is green, non-toxic and harmless, will not volatilize during product use, and will not harm human health.

[0088] Effect evaluation

[0089] The application effect of the coated modified anhydrous lithium hydroxide was evaluated. The coated modified anhydrous lithium hydroxide was applied to a semi-closed self-supply oxygen protective breathing device as a carbon dioxide absorbent generated by human respiration. The dust rate test result of the coated modified anhydrous lithium hydroxide used was 0.8%, and the highest carbon dioxide concentration in the head cover of the device was 1.8% after wearing and using the human respiration simulation device for 10 minutes. After using uncoated modified anhydrous lithium hydroxide, the dust rate test result was 4.7%, and the highest carbon dioxide concentration in the head cover of the device was 1.6% after wearing and using the human respiration simulation device for 10 minutes. It can be seen that the absorption rate of the coated modified anhydrous lithium hydroxide remains basically unchanged, and the dust rate is obviously improved.

[0090] Obviously, the above examples of the present application are only examples for clearly illustrating the present application, and are not limitations on the embodiments of the present application. For ordinary skilled persons in the art, other different forms of changes or variations can be made on the basis of the above description, and it is impossible to enumerate all the embodiments here. Any obvious changes or variations derived from the technical solutions of the present application still fall within the protection scope of the present application.

Claims

1. A method for producing a coated modified anhydrous lithium hydroxide, characterized by, The method comprises the following steps: Step 1: weigh the internal matrix and the external coating modifier; the internal matrix is anhydrous lithium hydroxide, and the external coating modifier is one of polyaspartic acid, polyacrylamide or polyacrylic acid; the molecular weight of the polyaspartic acid ranges from 2000 to 20000; the molecular weight of the polyacrylamide ranges from 20000 to 100000; and the molecular weight of the polyacrylic acid ranges from 500 to 5000; Step 2: dissolve the external coating modifier in deionized water to obtain a coating modifier solution; Step 3: coat the internal matrix with the coating modifier solution to obtain wet coated modified anhydrous lithium hydroxide; the mass ratio of the external coating modifier to the internal matrix ranges from 0.1% to 2.0%; Step 4: dry the wet coated modified anhydrous lithium hydroxide to obtain coated modified anhydrous lithium hydroxide.

2. The process for preparing the coating-modified anhydrous lithium hydroxide according to claim 1, characterized by, The anhydrous lithium hydroxide in Step 1 is in a granular form.

3. The process for preparing the coating-modified anhydrous lithium hydroxide according to claim 1, characterized by, The mass concentration of the external coating modifier in the coating modifier solution in Step 2 ranges from 0.1% to 8%.

4. The process for preparing the coating-modified anhydrous lithium hydroxide according to claim 1, characterized by, The coating method in Step 3 comprises: adding the internal matrix into the coating modifier solution; or uniformly spraying the coating modifier solution on the surface of the internal matrix. The drying conditions in Step 4 are as follows: temperature 90-150℃, and time 4-12h.

5. The process for preparing the coating-modified anhydrous lithium hydroxide according to claim 1, characterized by, The method comprises an internal matrix and an external coating modifier; the mass ratio of the external coating modifier to the internal matrix ranges from 0.1% to 2.0%; 6. The coated modified anhydrous lithium hydroxide prepared by the method of any one of claims 1 to 5, characterized in that: The internal matrix is granular anhydrous lithium hydroxide; The external coating modifier is one of polyaspartic acid, polyacrylamide or polyacrylic acid. The molecular weight of the polyaspartic acid is one of 4000, 6000-8000 and 10000-12000; the molecular weight of the polyacrylamide ranges from 20000 to 100000; and the molecular weight of the polyacrylic acid is one of 1000 and 3000.

7. The coated modified anhydrous lithium hydroxide of claim 6, wherein, ​

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