Modified porous adsorbing material for removing formaldehyde and preparation method thereof

Abstract

The present application relates to formaldehyde adsorption material technical field, specifically, it relates to the modified porous adsorption material for removing formaldehyde and its preparation method, the preparation method includes that functional liquid and porous carrier are mixed, dry processing again, obtain the modified porous adsorption material for removing formaldehyde;Wherein, functional liquid includes at least one of organic amine and amine modified ionic liquid, the water content of the modified porous adsorption material for removing formaldehyde after drying is 5-15%. The preparation method of the present application can improve the absorption, removal capacity of formaldehyde for the modified porous adsorption material for removing formaldehyde prepared.

Description

Technical Field

[0001] This invention relates to the field of formaldehyde adsorption materials technology, and more specifically, to modified porous adsorption materials for removing formaldehyde and their preparation methods. Background Technology

[0002] Formaldehyde is a common pollutant. To remove formaldehyde, related technologies add alkanolamines as loading agents to modified activated carbon used in indoor air purifiers. However, alkanolamines are highly volatile, and the released ammonia or organic amines can react with acidic substances, causing the filter material surface to turn white and affecting the user experience. Related technology US2012 / 0148858 discloses a method for reducing formaldehyde on or near a substrate containing amino-functionalized compounds (e.g., low molecular weight (<1000 g / mol) primary amines). While this combination does produce a removal effect, these organic amines produce foul odors and increase the VOC content in the coating, making it difficult to apply in air purifiers.

[0003] To address these issues, some technologies employ ionic liquids to prepare adsorbent materials for formaldehyde absorption. For example, in patent CN107308782A, Liu Zhanqi et al. combined triethanolamine, N,N-dimethylacetamide, N-methylacetamide, and water in a specific ratio to form an ionic liquid that is liquid at room temperature, thus absorbing formaldehyde. In patent CN104372610A, Geng Yunhua dissolved 5-7% of proanthocyanidins, equivalent to the weight of cotton fabric, in a 1-methyl-3-ethylimidazolium chloride ionic liquid to form a proanthocyanidin ionic liquid, which was then processed through impregnation, rolling, and drying to achieve formaldehyde removal.

[0004] However, since the physical adsorption between ionic liquids and formaldehyde is relatively weak, the formaldehyde absorption capacity of these ionic liquids still needs to be improved. Summary of the Invention

[0005] The purpose of this invention is to provide a modified porous adsorbent material for removing formaldehyde and a method for preparing the same. The method of this invention produces a modified porous adsorbent material for removing formaldehyde that can improve the absorption and removal capacity of formaldehyde.

[0006] This invention is implemented as follows:

[0007] In a first aspect, the present invention provides a method for preparing a modified porous adsorbent material for removing formaldehyde, comprising:

[0008] A functional liquid and a porous carrier are mixed and then dried to obtain a modified porous adsorbent material for removing formaldehyde. The functional liquid includes at least one of organic amine and amine-modified ionic liquid. The water content of the modified porous adsorbent material for removing formaldehyde after drying is 5-15%.

[0009] In an optional embodiment, the amine-modified ionic liquid includes an amino acid ionic liquid; wherein the amino acid ionic liquid is composed of at least one of alkali metal, alkaline earth metal, phosphorium, pyridinium, ammonium, guanidine, imidazoline, imidazoline, and sulfonium, and at least one of alanine, arginine, asparagine, aspartic acid, cysteine, glutamine, glutamic acid, glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine, and valine;

[0010] Organic amines include at least one of the following: adipate dihydrazide, succinate dihydrazide, polyethyleneimine, pentaethylenehexamine, tetraethylenepentamine, triethylenetetramine, diethylenetriamine, hexaethyleneheptamine, tri(2-aminoethyl)amine, tri[2-(methylamino)ethyl]amine, 2-(aminomethyl)-2-methyl-1,3-propanediamine, 1,4,7-triazacyclononane, aminosilane, amino-modified nanoparticles, ethylenediamine, propylenediamine, butylenediamine, pentanediamine, hexamethylenediamine, and piperazine.

[0011] In an optional embodiment, the amino acid ionic liquid is a compound containing a phosphonium substituent with 3 or more carbon atoms.

[0012] In an optional embodiment, the preparation method of the amino acid ionic liquid includes: mixing the ionic liquid with amino acids and stirring, drying to obtain a pre-prepared solid substance; and mixing the pre-prepared solid substance with an organic solvent.

[0013] In an optional embodiment, the mass concentration of the ionic liquid is 20-30%; the molar ratio of the ionic liquid to the amino acid is 1:1.

[0014] In an optional embodiment, the mass ratio of the pre-prepared solid material to the porous carrier in the amino acid ionic liquid is 0.5–2.5:2–4.

[0015] In an optional embodiment, the mass ratio of the pre-prepared solid material to the porous carrier in the amino acid ionic liquid is 2:3.

[0016] In an optional embodiment, the organic solvent includes at least one of a small molecule solvent and a eutectic solvent; wherein,

[0017] Small molecule solvents include at least one of tert-butanol and ethanol;

[0018] Eutectic solvents include at least one of polyethylene glycol, ethylene glycol, glycerol, tributyl phosphate, propylene carbonate, n-methylpyrrolidone, polyethylene glycol dimethyl ether, and polyethylene glycol dialkyl ether.

[0019] In an optional embodiment, the porous support includes at least one of silica gel, sepiolite, molecular sieve, alumina, and porous resin; the specific surface area of ​​the porous support is 20–1500 m². 2 / g; the average pore size of the porous support is 10–100 nm; the pore volume of the porous support is 0.1–1 cm³. 3 / g.

[0020] Secondly, the present invention provides a modified porous adsorbent material for removing formaldehyde, which is prepared by the preparation method of the modified porous adsorbent material for removing formaldehyde according to any of the foregoing embodiments.

[0021] The present invention has the following beneficial effects:

[0022] The preparation method of this invention utilizes a porous carrier as the "skeleton" of the formaldehyde removal functional agent. It has a large specific surface area and a well-developed pore structure, which is conducive to the dispersion of the formaldehyde removal functional agent, thereby increasing the contact between the formaldehyde removal functional agent and formaldehyde gas, thus increasing the mass transfer and reaction rate, and further improving the absorption and removal capacity of formaldehyde.

[0023] Furthermore, controlling the moisture content of the dried modified porous adsorbent material for formaldehyde removal to 5-15% ensures that the pores of the adsorbent material maintain appropriate gas diffusivity, thereby maintaining good formaldehyde adsorption performance. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0025] This invention provides a method for preparing a modified porous adsorbent material for removing formaldehyde, comprising: mixing a functional liquid and a porous carrier, and then drying the mixture to obtain the modified porous adsorbent material for removing formaldehyde; wherein the functional liquid includes at least one of an organic amine and an amine-modified ionic liquid, and the water content of the modified porous adsorbent material for removing formaldehyde after drying is 5-15%.

[0026] The preparation method of this invention utilizes a porous carrier as the "skeleton" of the formaldehyde removal functional agent. It has a large specific surface area and a well-developed pore structure, which is conducive to the dispersion of the formaldehyde removal functional agent, thereby increasing the contact between the formaldehyde removal functional agent and formaldehyde gas, thus increasing the mass transfer and reaction rate, and further improving the absorption and removal capacity of formaldehyde.

[0027] Typically, porous carriers contain micropores in a hydrated state, where gaseous components diffuse and adsorb. If micropores constitute the majority of the structure, pollutant molecules become difficult to diffuse within the modified pores, thus reducing capture efficiency. Conversely, if the microporous structure is not well-developed, diffusion within the micropores is difficult. In this invention, the moisture content of the dried modified porous adsorbent material for formaldehyde removal is controlled at 5–15%, ensuring that the micropores of the adsorbent material maintain appropriate gas diffusivity to preserve good formaldehyde adsorption performance.

[0028] In a preferred embodiment, the moisture content of the modified porous adsorbent material used for formaldehyde removal after drying is 5-10%, for example: 5%, 6%, 7%, 8%, 9%, 10%, etc., and no specific limitation is made here.

[0029] Optionally, the porous carrier includes at least one of silica gel, sepiolite, molecular sieve, alumina, and porous resin.

[0030] Optionally, the specific surface area of ​​the porous carrier is 20–1500 m². 2 / g, for example: 20m 2 / g, 50m 2 / g, 100m 2 / g、200m 2 / g、300m 2 / g、400m 2 / g、500m 2 / g、600m 2 / g、700m 2 / g、800m 2 / g、900m 2 / g, 1000m 2 / g、1100m 2 / g、1200m 2 / g、1300m 2 / g, 1400m 2 / g, 1500m 2 / g, etc., are not specifically limited here. In a preferred embodiment, the specific surface area of ​​the porous carrier is 400m². 2 / g.

[0031] Optionally, the average pore size of the porous carrier is 10–100 nm, such as 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, etc., and is not specifically limited herein. In a preferred embodiment, the average pore size of the porous carrier is 20–50 nm.

[0032] Optionally, the pore volume of the porous carrier is 0.1–1 cm³. 3 / g; for example: 0.1cm 3 / g, 0.2cm 3 / g, 0.3cm 3 / g, 0.4cm 3 / g, 0.5cm 3 / g, 0.6cm 3 / g, 0.7cm 3 / g, 0.8cm 3 / g, 0.9cm 3 / g, 1cm 3 / g, etc., are not specifically limited here. In a preferred embodiment, the pore volume of the porous carrier is 0.2 to 0.5 cm³. 3 / g.

[0033] Optionally, the organic amine includes at least one of adipic dihydrazide, succinic dihydrazide, polyethyleneimine, and polyamines; the polyamines further include at least one of pentaethylenehexamine, tetraethylenepentamine, triethylenetetramine, diethylenetriamine, hexaethyleneheptamine, tri(2-aminoethyl)amine, tri[2-(methylamino)ethyl]amine, 2-(aminomethyl)-2-methyl-1,3-propanediamine, 1,4,7-triazacyclononane, diamines, aminosilanes, and amino-modified nanoparticles (e.g., polyethyleneimine-modified silica nanoparticles or polyethyleneimine-modified carbon nanotubes); the diamines further include at least one of ethylenediamine, propylenediamine, butanediamine, pentanediamine, hexamethylenediamine, and piperazine.

[0034] Loading organic amines onto porous supports can promote their dispersion by utilizing the large specific surface area and well-developed pore structure of the porous material. This increases the contact area between the organic amines and formaldehyde, thereby increasing mass transfer and reaction rates, and ultimately improving the formaldehyde removal efficiency. However, organic amines tend to aggregate and volatilize, leading to reduced adsorption stability of the modified porous adsorbent material and making it prone to ammonia escape and decreased formaldehyde removal performance.

[0035] To mitigate the adverse effects of agglomeration and volatilization of organic amines, amine-modified ionic liquids can be loaded onto porous supports. Amine-modified ionic liquids are less prone to agglomeration and have lower volatility, thus reducing their formaldehyde removal performance. Amine-modified ionic liquids mainly refer to amino acid ionic liquids.

[0036] Optionally, the amino acid ionic liquid is composed of at least one of inorganic cations and organic cations, and a specific anion. The inorganic cations include at least one of alkali metals and alkaline earth metals; the organic cations include at least one of phosphorusium, pyridinium, ammonium, guanidineium, imidazolineium, imidazolineium, and sulfonium; the specific anion can be an amino acid, specifically including at least one of alanine, arginine, asparagine, aspartic acid, cysteine, glutamine, glutamic acid, glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine, and valine.

[0037] In a preferred embodiment, the amino acid ionic liquid is a compound containing phosphonium substituents with 3 or more carbon atoms, such as tetrabutylammonium proline, tetrabutylammonium serine, tetrabutylammonium lysine, tetrabutylammonium glycine, tetrabutylphosphonium proline, tetrabutylphosphonium serine, tetrabutylphosphonium lysine, and tetrabutylphosphonium glycine.

[0038] From the viewpoint of good compatibility with the monomers that form the polymer gel, in a more preferred embodiment, the amino acid ionic liquid is selected from at least one of tetrabutylphosphonic proline ([P4444][Pro]), tetrabutylphosphonic serine ([P4444][Ser]), tetrabutylphosphonic lysine ([P4444][Lys]), and tetrabutylphosphonic glycine ([P4444][Gly]).

[0039] Amino acid ionic liquids (AAILs) are ionic liquids containing amino acids as anions. Compared with traditional ionic liquids, they have advantages such as lower volatility, higher thermal stability, and tunable physicochemical properties. AAILs can be immobilized onto porous supports (e.g., mesoporous silica supports) via impregnation. The adsorption mechanism of AAIL@porous supports (e.g., AAIL@SiO2) for HCHO is mainly due to the ion exchange interaction between positively charged amino acid groups and negatively charged HCHO molecules; these interactions are strong and can withstand high temperatures, which contributes to the thermal stability of AAIL-modified silica.

[0040] Meanwhile, AAIL@porous supports (e.g., AAIL@SiO2) exhibit better stability than amine-modified porous supports in terms of thermal stability and resistance to water or oxygen degradation. This is because amino acid ionic liquids (AAILs) have lower volatility, higher thermal stability, and tunable physicochemical properties compared to ionic liquids. Amino acid ionic liquids (AAILs) can also form stable complexes, preventing the loss of adsorbed components due to evaporation or oxidation.

[0041] Formaldehyde is captured by AAIL@porous carriers through physical and chemical adsorption mechanisms; the hydrogen bonds in these amino acid ionic liquids (AAILs) result in high viscosity, and the viscosity increases sharply after formaldehyde absorption, thereby improving the ability to capture and remove formaldehyde and effectively preventing aldehyde escape, which would reduce the removal performance.

[0042] Optionally, the preparation method of amino acid ionic liquid includes: mixing and stirring the ionic liquid with amino acids, drying to obtain a pre-prepared solid substance; and mixing the pre-prepared solid substance with an organic solvent.

[0043] Furthermore, the mass concentration of the ionic liquid is 20-30%; the molar ratio of the ionic liquid to the amino acid is 1:1.

[0044] Furthermore, the mass ratio of the pre-prepared solid material to the porous carrier in the amino acid ionic liquid is 0.5–2.5:2–4. The pore structure of the modified porous adsorbent material has a significant impact on formaldehyde adsorption. Larger pore volumes can accommodate more functional formaldehyde removal agents (i.e., organic amines or amino acid ionic liquids), thereby improving formaldehyde removal capacity. However, as the loading of functional formaldehyde removal agents increases, the thickness of the agent loaded on the porous carrier surface increases, leading to an increase in mass transfer resistance, which adversely affects the adsorption rate. Optimizing the mass ratio of the pre-prepared solid material to the porous carrier in the amino acid ionic liquid is essential to ensure efficient adsorption and removal of formaldehyde.

[0045] In a preferred embodiment, the mass ratio of the pre-prepared solid material to the porous carrier in the amino acid ionic liquid is 2:3.

[0046] Optionally, the organic solvent includes at least one of a small molecule solvent and a eutectic solvent; wherein the small molecule solvent includes at least one of tert-butanol and ethanol; and the eutectic solvent includes at least one of polyethylene glycol, ethylene glycol, glycerol, tributyl phosphate, propylene carbonate, n-methylpyrrolidone, polyethylene glycol dimethyl ether, and polyethylene glycol dialkyl ether. The addition of small molecule solvents and / or eutectic solvents can reduce the viscosity of organic amines or amine-modified ionic liquids, facilitating the reliable loading of organic amines or amine-modified ionic liquids onto porous materials, reducing agglomeration, and forming a solid hybrid material that reliably removes formaldehyde.

[0047] The present invention will be further described in detail below with reference to the embodiments.

[0048] Example 1

[0049] Weigh 25wt% tetrabutylphosphine hydroxide aqueous solution ([P4444]OH) and lysine (Lys) in a 1:1 molar ratio and add them to a 250ml round-bottom flask. Stir magnetically at room temperature for 12h. Remove excess water by rotary evaporation at 70℃ and dry to constant weight at 100℃ to obtain tetrabutylphosphonium lysine salt [P4444][lys].

[0050] 2 g of [P4444][lys] was added to a 100 mL round-bottom flask equipped with a magnetic stirrer; 10 mL of ethanol (99 vol%) and 1 g of polyethylene glycol 200 solution were added, followed by 3 g of silica gel. The suspension was stirred overnight. Excess water was then removed by rotary evaporation at 70 °C to obtain a modified porous adsorbent material for formaldehyde removal, with a water content of 5%.

[0051] Example 2

[0052] The difference between Example 2 and Example 1 is that lysine is replaced with glycine of equal molar mass, while the remaining steps and process parameters are the same as in Example 1; and the water content of the modified porous adsorbent material used to remove formaldehyde is 10%.

[0053] Example 3

[0054] The difference between Example 3 and Example 1 is that lysine is replaced with equimolar proline, and the remaining steps and process parameters are the same as in Example 1; and the water content of the modified porous adsorbent material used to remove formaldehyde is 15%.

[0055] Example 4

[0056] The difference between Example 4 and Example 1 is that the mass of [P4444][lys] is changed to 0.67g, while the remaining steps and process parameters are the same as in Example 1; and the water content of the modified porous adsorbent material used to remove formaldehyde is 12%.

[0057] Example 5

[0058] The difference between Example 5 and Example 1 is that the mass of [P4444][lys] is changed to 2.25g, while the remaining steps and process parameters are the same as in Example 1, and the water content of the modified porous adsorbent material used to remove formaldehyde is 15%.

[0059] Example 6

[0060] The difference between Example 6 and Example 1 is that an equal amount of polyethyleneimine organic amine is used to replace [P4444][lys] on the silicone, while the remaining steps and process parameters are the same as in Example 1.

[0061] Comparative Example 1

[0062] The ionic liquid [P4444] was directly mixed with hydrophobic silica gel and dried to obtain [P4444] ionic liquid modified silica gel, that is, the ionic liquid [P4444] was not modified with amino acids.

[0063] Comparative Example 2

[0064] 2g of lysine was dissolved directly in 10mL of ethanol and 1g of polyethylene glycol 200 solution, then 3g of silica gel was added, mixed and dried to obtain lysine-modified silica gel.

[0065] Comparative Example 3

[0066] 2g of glycine was dissolved directly in 10mL of ethanol and 1g of polyethylene glycol 200 solution, then 3g of silica gel was added, mixed and dried to obtain lysine-modified silica gel.

[0067] Comparative Example 4

[0068] 2g of proline was dissolved directly in 10mL of ethanol and 1g of polyethylene glycol 200 solution, then 3g of silica gel was added, mixed and dried to obtain lysine-modified silica gel.

[0069] The formaldehyde removal performance of the porous adsorbent materials in each embodiment and comparative example was tested, and the formaldehyde removal performance of the porous adsorbent materials in each embodiment and comparative example after aging was also tested. The attenuation rate after aging was compared (attenuation rate = (formaldehyde removal rate before aging - formaldehyde removal rate after aging) / formaldehyde removal rate before aging × 100%). The aging method was to place each porous adsorbent material in an 80℃ oven and heat it for 24 hours to obtain the formaldehyde removal modified carrier after high temperature aging.

[0070] The test method for formaldehyde removal performance includes: testing the formaldehyde gas removal rate in a 30L acrylic chamber for 30 minutes. The amount of sample added in each embodiment and comparative example is 1g. The gas concentration is measured using a GASTEC detection tube. The removal rate of the gas after the specified time is calculated based on the initial concentration and the final concentration. The test results are shown in Table 1 and Table 2.

[0071] Table 1

[0072]

[0073] Table 1 shows that the lysine ionic liquid loaded onto the porous adsorbent material exhibits stronger adsorption performance for formaldehyde. This is because lysine has more amino groups than other agents. The stability of the amino acid-modified porous adsorbent carrier alone is insufficient. Comparative Examples 2-4 showed a significant decrease in formaldehyde removal performance after aging at 80 degrees Celsius for 24 hours, while the amino acid ionic liquid-modified porous carriers in Examples 1-3 showed a significantly lower rate of degradation.

[0074] Table 2

[0075]

[0076] Table 2 shows that different concentrations of ionic liquid modified silica gel have different effects on formaldehyde removal performance. The comparison results indicate that both high and low concentrations of ionic liquid reduce the formaldehyde removal rate. Specifically, low-concentration ionic liquid-modified silica gel has limited active groups loaded on it, hindering faster formaldehyde capture. High-concentration ionic liquid causes pore blockage, preventing formaldehyde molecules from entering the pores, with only a small portion of the surface active groups reacting with the formaldehyde. Therefore, optimizing the concentration of the amino acid ionic liquid used to improve porous materials can yield materials with excellent formaldehyde removal performance.

[0077] In summary, the preparation method of the present invention can prepare adsorbent materials with excellent formaldehyde adsorption performance and high temperature aging resistance, which can be used in various application environments that require formaldehyde removal.

[0078] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a modified porous adsorbent material for removing formaldehyde, characterized in that, include: A functional liquid and a porous carrier are mixed and then dried to obtain a modified porous adsorbent material for formaldehyde removal; wherein the functional liquid includes an amine-modified ionic liquid, and the water content of the modified porous adsorbent material for formaldehyde removal after drying is 5-15%; The amine-modified ionic liquid includes an amino acid ionic liquid. The preparation method of the amino acid ionic liquid includes: mixing the ionic liquid with amino acids and stirring, drying to obtain a pre-prepared solid substance; and mixing the pre-prepared solid substance with an organic solvent. The mass concentration of the ionic liquid is 20-30%; the molar ratio of the ionic liquid to the amino acid is 1:

1. The mass ratio of the pre-prepared solid material to the porous carrier in the amino acid ionic liquid is 0.5~2.5:2~4.

2. The method for preparing the modified porous adsorbent material for formaldehyde removal according to claim 1, characterized in that, The amino acid ionic liquid is composed of at least one of phosphorus, pyridinium, ammonium, guanidinium, imidazoline, imidazoline, and sulfonium, and at least one of alanine, arginine, asparagine, aspartic acid, cysteine, glutamine, glutamic acid, glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine, and valine.

3. The method for preparing the modified porous adsorbent material for formaldehyde removal according to claim 2, characterized in that, The amino acid ionic liquid is a compound containing phosphonium substituents with 3 or more carbon atoms.

4. The method for preparing the modified porous adsorbent material for formaldehyde removal according to claim 1, characterized in that, The mass ratio of the pre-prepared solid material to the porous carrier in the amino acid ionic liquid is 2:

3.

5. The method for preparing the modified porous adsorbent material for formaldehyde removal according to claim 1, characterized in that, The organic solvent includes at least one of small molecule solvents and eutectic solvents; wherein... The small molecule solvent includes at least one of tert-butanol and ethanol; The eutectic solvent includes at least one of polyethylene glycol, ethylene glycol, glycerol, tributyl phosphate, propylene carbonate, n-methylpyrrolidone, polyethylene glycol dimethyl ether, and polyethylene glycol dialkyl ether.

6. The method for preparing the modified porous adsorbent material for formaldehyde removal according to claim 1, characterized in that, The porous carrier comprises at least one of silica gel, sepiolite, molecular sieve, alumina, and porous resin; the specific surface area of ​​the porous carrier is 20~1500 m². 2 / g; the average pore size of the porous support is 10~100nm; the pore volume of the porous support is 0.1~1cm³. 3 / g.

7. A modified porous adsorbent material for removing formaldehyde, characterized in that, It is prepared by the method for preparing the modified porous adsorbent material for removing formaldehyde as described in any one of claims 1-6.

Images