A composite purification material and preparation method thereof

Abstract

The present invention belongs to the field of air purification, and specifically relates to a composite purification material and a preparation method thereof. The method comprises: 1) taking a silicate and a solvent and mixing them evenly, adjusting the pH value and adding a surfactant and a structure directing agent to mix evenly, adding manganate while stirring, filtering, cleaning, aging and drying the system after the reaction is complete to obtain a silicon-based precursor; 2) heating and crystallizing the silicon-based precursor, cleaning and drying the product after cooling to obtain a silicon-based adsorbent, mixing the silicon-based adsorbent and a copper salt solution evenly, and then ultrasonically treating the mixture, and then cleaning, drying and high-temperature treating to obtain a composite purification material. The composite purification material prepared by the present invention can quickly adsorb pollutant molecules in the air, can efficiently adsorb and degrade formaldehyde, and can keep the formaldehyde concentration below the safety standard concentration for a long time, while ensuring that the molecules inside the material can still be smoothly transported in a high humidity environment, and the regeneration effect is good.

Description

Technical Field

[0001] The invention belongs to the field of air purification, and in particular relates to a composite purification material and a preparation method thereof. Background Art

[0002] With the continuous improvement of living standards, indoor environmental protection and health issues have gradually become the focus of people's attention. Office buildings, shopping malls and other places are relatively closed, which greatly reduces the exchange with outdoor air, and the content of negative oxygen ions in the air is low. Due to human activities, various dust, mold, bacteria and other harmful substances are easily accumulated in indoor places such as office buildings and shopping malls. Volatile gas pollutants such as formaldehyde, benzene, and toluene produced by artificial boards used in decoration are also one of the sources of air pollution. The relatively closed building environment causes these pollutants to accumulate. Among them, formaldehyde is widely present as a harmful pollutant with carcinogenic risks, and most of the commercially available air purification materials are mainly used to adsorb pollutant molecules, lacking degradation and purification. Within a few months after decoration, most volatile gas pollutants can be adsorbed by commercially available air purification materials, but the release cycle of formaldehyde is as long as several years, and the long-term adsorption effect of the material is insufficient, resulting in a rebound in formaldehyde concentration.

[0003] Among the materials prepared by the prior art, chlorine dioxide and organic amines are mainly used to degrade formaldehyde, but they are prone to secondary chemical pollution; and the purification effect of biodegradation is insufficient and is prone to leakage. This field also uses strong light to irradiate electrons and degrades them through oxidative free radicals generated by electron valence transitions, but the excitation conditions of a single degradation material are relatively strict and are not suitable for indoor places such as office buildings and shopping malls. At the same time, water molecules will block the pores of the composite material, and carbon dioxide will affect the pore size of the material after being adsorbed by the composite material. After a period of time, competitive adsorption causes the composite material's purification effect on the air to be significantly weakened. Summary of the invention

[0004] Based on the above content, in order to solve the problems of high formaldehyde content and continuous release in closed indoor places such as office buildings and shopping malls, insufficient air purification effect of materials prepared by existing technology, and easy failure of materials in contact with water, the present invention proposes a composite purification material and a preparation method thereof.

[0005] The objects of the present invention are:

[0006] 1. Prepare a composite purification material that can quickly adsorb pollutant molecules;

[0007] 2. Ensure the long-term purification effect of composite purification materials on air;

[0008] 3. Overcome the problem that composite purification materials are easily ineffective when exposed to water.

[0009] To achieve the above objectives, the present invention adopts the following technical solutions.

[0010] A method for preparing a composite purification material.

[0011] The method comprises:

[0012] 1) Take silicate and solvent and mix them evenly, adjust the pH value and add surfactant and structure directing agent to mix evenly, keep stirring and add manganate, after the reaction is complete, filter, wash, age and dry the system to obtain a silicon-based precursor;

[0013] 2) The silicon-based precursor is heated and crystallized, and after cooling, the product is cleaned and dried to obtain a silicon-based adsorbent, the silicon-based adsorbent and the copper salt solution are evenly mixed and then subjected to ultrasonic treatment, and the composite purification material is obtained after cleaning, drying and high-temperature treatment.

[0014] As a preference,

[0015] Step 1) the silicate is sodium silicate;

[0016] Step 1) The solvent is water, and the amount used is 15-35 mL / g silicate;

[0017] In step 1), the pH value is adjusted to 7.35-7.44.

[0018] As a preference,

[0019] Step 1) The surfactant is hexadecyltrimethylammonium bromide, and the amount used is 0.02-0.03 g / g silicate;

[0020] Step 1) the structure directing agent is tetrapropylammonium hydroxide, and the amount thereof is 0.1 to 0.15 g / g silicate;

[0021] Step 1) The manganate is sodium permanganate, and its dosage is 1.17-1.28 g / g silicate.

[0022] As a preference,

[0023] The aging in step 1) is carried out at a constant temperature of 45 to 50°C for 20 to 22 hours.

[0024] As a preference,

[0025] Step 2) The heating crystallization process is:

[0026] The silicon-based precursor is evenly distributed on the carrier, 0.5-0.8 mL of water is added per gram of silicon-based precursor, and the device is sealed for water vapor-assisted crystallization, and the temperature is kept constant at 155-165 °C for 23.5-24.5 h.

[0027] As a preference,

[0028] Step 2) The copper salt solution is a saturated copper nitrate solution, and its dosage is 0.3-0.5 mL / g silicon-based adsorbent.

[0029] As a preference,

[0030] Step 2) The duration of the ultrasonic treatment is 4 to 5 hours;

[0031] Step 2) The high temperature treatment is carried out at 600-650°C for 4-4.5 hours.

[0032] A composite purification material.

[0033] In the technical solution of the present invention, a multi-level porous silicon-based composite material for purifying air is constructed. The present invention uses sodium silicate (Na2O·nSiO2, n is the modulus of sodium silicate) as a raw material. Since the modulus of sodium silicate significantly affects its solubility, the present invention selects a sodium silicate raw material with a modulus of 1, which can be dissolved in water at room temperature. Sodium silicate is easy to hydrolyze, and constructing an alkaline environment can reduce the content of H2SiO3 in the system. At the same time, sodium permanganate can be hydrolyzed to form a black manganese dioxide precipitate under the specific pH value conditions constructed by the present invention.

[0034] Within a certain pH range, as the OH - As the ion content increases, abundant pores appear in the silicon-based precursor, and the pore wall area that can contact formaldehyde increases. The weak alkaline environment is conducive to the formation of abundant oxygen vacancies, which is conducive to adjusting the electronic structure of the material surface. The active oxygen (O 2- , O - 、O2 2- ) can improve the conversion effect of formaldehyde. However, adding high concentration of alkali solution will cause the crystal structure of the material to change, MnO4 - With OH - Reaction to form MnO4 2- The byproducts with high manganese valence are formed. Some holes are difficult to maintain their original state, resulting in serious structural damage. Therefore, the present invention limits the concentration of the alkali solution.

[0035] Since the wet semi-crystalline gel is prone to crack or bend due to the capillary force generated by water volatilization exceeding its skeleton strength during heat treatment, destroying its original structure, the present invention adds a surfactant to reduce the surface tension of water. In addition, the type of surfactant will also have a more significant effect on the morphology of the material. It can be used as a soft template to promote the formation of micropores and induce the direction of crystal growth, which is conducive to the construction of a highly ordered porous structure. However, the specific surface area of ​​a single mesoporous structure is small and the activity is weak, resulting in a low utilization rate of the active sites of the material in an environment with a high formaldehyde concentration, which obviously causes a decrease in adsorption performance. Materials with only a single mesoporous structure are prone to block the pores due to water molecules and cannot achieve rapid adsorption, transportation, and contact catalysis of formaldehyde. Therefore, it is necessary to introduce small holes with smaller sizes to effectively intercept water molecules, which is also the focus of the present invention. Due to the special weakly alkaline environment mentioned above, the present invention cannot use the acid treatment and alkali treatment methods commonly used in the art to introduce small holes.

[0036] The present invention adds tetraethylammonium hydroxide and performs aging. Within a certain period of time, Si-MnO2 seed crystals are formed, and the material is initially aged and solidified to a semi-crystalline colloid. Further, the present invention heats and crystallizes the silicon-based precursor. Due to the synergistic effect of the non-volatile quaternary ammonium salt of tetraethylammonium hydroxide, water vapor assists the product to remove part of the silicon to form intracrystalline micropores. The intracrystalline micropores have fish-scale burrs, which can provide support for the subsequent copper species to form a network structure. In this process, the crystallization temperature and crystallization time will have a significant impact on the product. Too high a temperature causes the product purity to decrease and also aggregate, while too low a temperature causes the product to break and the intracrystalline binding force is poor; a short crystallization time will obviously cause a low degree of crystallization, and a long crystallization process will cause the product to dissolve, and the grains are small. The number of nuclei in the saturated copper salt solution is abundant, and copper ions are adsorbed into the silicon-based adsorbent. The formed nano-chips are accumulated near the burrs of the intracrystalline micropores, and the chips are interspersed with each other to form an ultra-microporous network structure, realizing the introduction of small holes.

[0037] The present invention performs ultrasonic treatment on the system, during which copper and silicon-based materials form intermediates. High temperature induces copper-manganese interaction, which activates and produces more highly active oxygen species. At the same time, copper species migrate at high temperatures and are captured by oxygen defects to form ion exchange and doping, so that they can avoid agglomeration at high temperatures. The activity of the copper-manganese active sites and oxygen vacancy sites of the material is greatly improved, which enhances the activation and adsorption of harmful gas molecules by the material and can form stable chemical adsorption bonds. Among them, the adsorbed formaldehyde molecules are not easy to desorb, and the chemical adsorption bonds will not break spontaneously, which is conducive to significantly reducing the formaldehyde concentration in the air.

[0038] The silicon-based skeleton in the present invention can play a good supporting role, and with the help of aging and other methods, it can improve the stability of the material, thereby ensuring that the material can purify the air for a long time. The larger holes in the multi-level porous material constructed by the present invention can provide a relatively spacious mass transfer channel, which can ensure that the gas can smoothly enter the material, accelerate the adsorption rate of the gas, achieve rapid mass transfer, and improve the utilization rate of the adsorption sites. The smaller holes are conducive to intercepting water molecules, so that the material has a large specific surface area, adsorption capacity and abundant adsorption sites. At room temperature, the material can absorb moisture. Since formaldehyde is highly hydrophilic, the material generates heat after absorbing moisture, which enhances the material's adsorption and degradation of formaldehyde. When the formaldehyde molecules are rapidly adsorbed to the active sites of the material, they react with active oxygen to form DOM and HCOO - The intermediates, due to the synergistic effect of the material's moisture absorption and heat generation, are completely converted into harmless carbon dioxide and released into the environment.

[0039] That is, the present invention actually enhances the adsorption and degradation of formaldehyde through hydrophilicity, and at the same time constructs a multi-level pore structure to form "inner filtration" to ensure that the adsorption and catalytic degradation processes can be relatively effectively balanced, and the comprehensive purification efficiency is maximized.

[0040] The beneficial effects of the present invention are as follows:

[0041] (1) The composite purification material prepared by the present invention can quickly adsorb pollutant molecules in the air;

[0042] (2) The composite purification material prepared by the present invention can efficiently adsorb and degrade formaldehyde, and keep the formaldehyde concentration below the safety standard concentration for a long time;

[0043] (3) The composite purification material prepared by the present invention has a humidity regulating effect, that is, it ensures that the molecules inside the material can still be transported smoothly in a high humidity environment, and the regeneration effect is good. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a SEM characterization image of the sample prepared in Example 1;

[0045] Figure 2 This is the SEM characterization image of the sample prepared in Comparative Example 1. DETAILED DESCRIPTION

[0046] The present invention is further described in detail below in conjunction with specific embodiments and the accompanying drawings. A person of ordinary skill in the art will be able to implement the present invention based on these descriptions. In addition, the embodiments of the present invention involved in the following description are generally only embodiments of a part of the present invention, rather than all embodiments. Therefore, based on the embodiments of the present invention, all other embodiments obtained by a person of ordinary skill in the art without making creative work should fall within the scope of protection of the present invention.

[0047] Unless otherwise specified, the raw materials used in the examples of the present invention are all commercially available or available to those skilled in the art; unless otherwise specified, the methods used in the examples of the present invention are all methods known to those skilled in the art.

[0048] Embodiment 1: A method for preparing a composite purification material, the method comprising:

[0049] 1) Take 10 g of sodium silicate and 200 mL of water and mix them evenly. Add sodium hydroxide solution to adjust the pH value of the system to 7.35. Add 0.2 g of hexadecyltrimethylammonium bromide and 1 g of tetrapropylammonium hydroxide and mix them evenly. While stirring, slowly add 11.7 g of sodium permanganate within 10 min. After the reaction is complete, filter and wash the system, keep the temperature at 45 °C for 22 h, and dry the product to obtain a silicon-based precursor.

[0050] 2) The silicon-based precursor is evenly distributed on the carrier, 0.5 mL of water is added per gram of silicon-based precursor, the device is sealed for water vapor-assisted crystallization, and the crystallization is carried out at a constant temperature of 160 ° C for 24 h. After the device is cooled to room temperature, the product is washed and dried to obtain a silicon-based adsorbent, 0.3 mL of saturated copper nitrate solution is added to the silicon-based adsorbent per gram of silicon-based adsorbent and mixed evenly, and it is ultrasonically treated for 4 h. After washing and drying, the product is placed at 650 ° C and kept at a constant temperature for 4 h to obtain a composite purification material.

[0051] The SEM characterization results of the obtained composite purification material are as follows Figure 1 As shown, it can be seen that the composite purification material of the present invention constructs a rich and multi-level pore structure. This composite pore structure can more efficiently and effectively realize the adsorption-transport-catalysis-release cycle, and exhibits a larger specific surface area and greater catalytic activity.

[0052] The composite purification material prepared in this example was subjected to performance tests, including formaldehyde adsorption test, formaldehyde degradation test and regeneration test, and the tests were carried out under dry air conditions, wet air conditions and extreme humidity conditions, respectively.

[0053] in:

[0054] Dry air conditions simulate the air humidity of the northern climate, and the relative humidity is controlled at RH=25%;

[0055] The humid air condition simulates the air humidity of the southern climate and controls the relative humidity RH=70%;

[0056] The extreme humidity condition simulates the air humidity during the rainy season in some parts of southern China, and controls the relative humidity RH=90%.

[0057] The core lies in the simulation of extreme humidity conditions, because for the vast majority of current formaldehyde-removing materials, humidity is the main reason for the decline in their actual performance, and for the southern region, it is a very suitable time period to carry out hard and soft decoration of houses before and after the rainy season, because the general suitable months for decoration are March to August, but the rainy season in most parts of the south will last from May to July, so there is a large part of the overlap. This leads to a large amount of formaldehyde being produced during the decoration process and when furniture is brought in after the decoration is completed, and the performance of the formaldehyde-removing materials is affected by humidity, which will cause the indoor formaldehyde to drop to a safe range. It takes a longer time. Therefore, the researchers of the present invention specifically use the above conditions for testing and comparison.

[0058] The formaldehyde adsorption test is to place the air purification material to be tested in a closed container (2.25 m 3 The formaldehyde gas was filled into the tank at one time and the initial formaldehyde concentration was controlled to be 2.00 mg / m 3 The amount of air purification material to be tested is 200 g / m 3 The formaldehyde concentration in the sealed container was detected to be 0.08 mg / m 3 The length of time required.

[0059] The formaldehyde degradation test is to place the air purification material to be tested in a closed container (2.25 m 3 6.0 mol of formaldehyde gas was filled into the air filter at one time, and the amount of air purification material to be tested was 200 g / m 3 The formaldehyde concentration in the container was detected every 2 hours, and continuous real-time monitoring was carried out for a total of 36 hours to calculate the formaldehyde removal rate.

[0060] The regeneration test is to place the air purification material in a closed container (2.25 m 3The air purification material was tested every 2 h until the formaldehyde concentration did not decrease significantly within two tests, and then it was determined that the air purification material had failed. The regeneration treatments were carried out by exposing it to light for 12 h (-L12) and heating it to 200 ℃ for 3 h (-H200). After the regeneration was completed, the formaldehyde adsorption capacity (Ad) and formaldehyde degradation capacity (De) were characterized, and the performance recovery rate was calculated by comparing with the original performance. Among them, the formaldehyde degradation ability (De) characterizes the removal rate percentage calculated by comparing the typical value of 12 h before and after regeneration (i.e., removal rate after regeneration / removal rate before regeneration × 100%). The formaldehyde adsorption test results characterize the time before and after regeneration, so "+" means that the time to reach the standard safety concentration is extended and the performance is reduced, and "-" means that the time to reach the standard safety concentration is shortened and the performance is improved. Time less than 1 min is calculated as 1 min, that is, 1.6 min is recorded as 2 min.

[0061] The characterization results are shown in the following table.

[0062]

[0063] From the above characterization results, it can be clearly seen that the composite purification material for the technical solution of the present invention performs much better than the dry air condition simulation under wet air and extreme humidity conditions, and in an environment with high humidity, the characterization results are relatively similar, showing very excellent air purification capabilities, which is conducive to the effective removal of formaldehyde. However, the difference is that for the composite purification material system of the present invention, although its performance can be regenerated under both exposure and heating conditions, the degree of regeneration after failure under different conditions is different. When regenerated after failure under dry air conditions, the degradation force remains relatively good, but for adsorption force, it is obvious that the regeneration effect of exposure on adsorption force is relatively limited, but heat treatment can obviously achieve excellent regeneration effect. For the regeneration of failure under high humidity conditions, exposure is obviously not enough to achieve comprehensive and effective regeneration. The R&D personnel believe that it may be due to the multi-level pore structure of the present invention that the exposure regeneration effect is relatively limited, and extending the exposure time can further improve the regeneration rate.

[0064] Embodiment 2: A method for preparing a composite purification material, the method comprising:

[0065] 1) Take 10 g of sodium silicate and 200 mL of water and mix them evenly, add sodium hydroxide solution, adjust the pH value of the system to 7.39, add 0.2 g of hexadecyltrimethylammonium bromide and 1 g of tetrapropylammonium hydroxide and mix them evenly, while keeping stirring, slowly add 11.7 g of sodium permanganate, filter and wash the system after the reaction is complete, keep the temperature at 45 °C for 22 h, and dry the product to obtain a silicon-based precursor;

[0066] 2) The silicon-based precursor is evenly distributed on the carrier, 0.5 mL of water is added per gram of silicon-based precursor, the device is sealed for water vapor-assisted crystallization, and the crystallization is carried out at a constant temperature of 160 ° C for 24 h. After the device is cooled to room temperature, the product is washed and dried to obtain a silicon-based adsorbent, 0.3 mL of saturated copper nitrate solution is added to the silicon-based adsorbent per gram of silicon-based adsorbent and mixed evenly, and it is ultrasonically treated for 4 h. After washing and drying, the product is placed at 650 ° C and kept at a constant temperature for 4 h to obtain a composite purification material.

[0067] The composite purification material prepared in this example was subjected to the same performance test as in Example 1, and the results are as follows.

[0068]

[0069] At the same time, electron microscopy characterization revealed that the pore size of the core material of Example 1 was slightly larger than that of the core material of Example 2. The material of Example 2, which has more pore structures and smaller pores, has a larger specific surface area and thus exhibits higher catalytic activity. According to the results in the table, it can be seen that with the increase in the concentration of the alkali solution, the large number of pores in the silicon-based precursor increases the specific surface area of ​​the material, which is beneficial to increase the contact rate with formaldehyde for catalysis. By comparison, it was found that after regeneration, the adsorption force of the material in this example decreased slightly, but the catalytic rate increased. In terms of regeneration, there was no significant difference.

[0070] Embodiment 3: A method for preparing a composite purification material, the method comprising:

[0071] 1) Take 10 g of sodium silicate and 200 mL of water and mix them evenly, add sodium hydroxide solution, adjust the pH value of the system to 7.44, add 0.2 g of hexadecyltrimethylammonium bromide and 1 g of tetrapropylammonium hydroxide and mix them evenly, while keeping stirring, slowly add 11.7 g of sodium permanganate, filter and wash the system after the reaction is complete, keep the temperature at 45 °C for 22 h, and dry the product to obtain a silicon-based precursor;

[0072] 2) The silicon-based precursor is evenly distributed on the carrier, 0.5 mL of water is added per gram of silicon-based precursor, the device is sealed for water vapor-assisted crystallization, and the crystallization is carried out at a constant temperature of 160 ° C for 24 h. After the device is cooled to room temperature, the product is washed and dried to obtain a silicon-based adsorbent, 0.3 mL of saturated copper nitrate solution is added to the silicon-based adsorbent per gram of silicon-based adsorbent and mixed evenly, and it is ultrasonically treated for 4 h. After washing and drying, the product is placed at 650 ° C and kept at a constant temperature for 4 h to obtain a composite purification material.

[0073] The composite purification material prepared in this example was subjected to the same performance test as in Example 1, and the results are as follows.

[0074]

[0075] According to the results in the table, it can be seen that due to the formation of MnO4 2- The byproducts with high manganese valence state such as ions caused some pore structures to be damaged. Electron microscopy showed that compared with Example 2, the pore size of the material in this example was smaller, but because the sodium ions covered some active oxygen sites, the overall adsorption and catalytic performance of the material were not as good as those in Example 2.

[0076] Comparative Example 1: A method for preparing a composite purification material, the method comprising:

[0077] 1) Take 10 g of sodium silicate and 200 mL of water and mix them evenly, add sodium hydroxide solution, adjust the pH value of the system to 7.39, add 0.2 g of hexadecyltrimethylammonium bromide and mix evenly, and slowly add 11.7 g of sodium permanganate while stirring. After the reaction is complete, filter and wash the system, and dry the product to obtain a silicon-based precursor;

[0078] 2) The silicon-based precursor is evenly distributed on the carrier, 0.5 mL of water is added per gram of silicon-based precursor, the device is sealed for water vapor-assisted crystallization, and the crystallization is carried out at a constant temperature of 160 ° C for 24 h. After the device is cooled to room temperature, the product is washed and dried to obtain a silicon-based adsorbent, 0.3 mL of saturated copper nitrate solution is added to the silicon-based adsorbent per gram of silicon-based adsorbent and mixed evenly, and it is ultrasonically treated for 4 h. After washing and drying, the product is placed at 650 ° C and kept at a constant temperature for 4 h to obtain a composite purification material.

[0079] The composite purification material prepared in this example was subjected to the same performance test as in Example 1, and the results are as follows.

[0080]

[0081] In addition, the SEM characterization results are as follows Figure 2As shown. In this example, a material with a relatively single mesoporous pore structure was obtained by alkali treatment without using tetrapropylammonium hydroxide as a structure-directing agent. No obvious stratification and / or hierarchical structure was produced. At the same time, the alkali solution concentration in this example was insufficient, and the pore expansion effect on the material was poor. The copper species loading rate in this material is low, and the copper species is easily lost due to the lack of fish-scale support structure. According to the results in the table, the material has a poor adsorption effect on formaldehyde. The single pore structure significantly limits the diffusion of formaldehyde molecules, the utilization rate of active sites inside the material is low, and the material is easy to lose activity. Therefore, the material in this example cannot adsorb formaldehyde for a long time, and the regeneration performance is also reduced.

[0082] Comparative Example 2: A method for preparing a composite purification material, the method comprising:

[0083] 1) Take 10 g of sodium silicate and 200 mL of water and mix them evenly, add sodium hydroxide solution, adjust the pH value of the system to 7.39, add 1 g of tetrapropylammonium hydroxide and mix evenly, while keeping stirring, slowly add 11.7 g of sodium permanganate, filter and wash the system after the reaction is complete, keep the temperature at 45 °C for 22 h, and dry the product to obtain a silicon-based precursor;

[0084] 2) The silicon-based precursor is evenly distributed on the carrier, 0.5 mL of water is added per gram of silicon-based precursor, the device is sealed for water vapor-assisted crystallization, and the crystallization is carried out at a constant temperature of 160 ° C for 24 h. After the device is cooled to room temperature, the product is washed and dried to obtain a silicon-based adsorbent, 0.3 mL of saturated copper nitrate solution is added to the silicon-based adsorbent per gram of silicon-based adsorbent and mixed evenly, and it is ultrasonically treated for 4 h. After washing and drying, the product is placed at 650 ° C and kept at a constant temperature for 4 h to obtain a composite purification material.

[0085] The composite purification material prepared in this example was subjected to the same performance test as in Example 1, and the results are as follows.

[0086]

[0087] The materials of the present invention all have rich pore structures. Under the influence of high-strength capillary force, the wet semi-crystalline colloid is expanded and deformed by the surface tension of water during heat treatment, that is, the pore structure is destroyed, and it is impossible to construct a highly ordered porous and hierarchical / layered porous structure. According to the results in the table, the adsorption and catalytic degradation performance of the material for formaldehyde is significantly reduced.

[0088] Comparative Example 3: A method for preparing a composite purification material, the method comprising:

[0089] 1) Take 10 g of sodium silicate and 200 mL of water and mix them evenly, add sodium hydroxide solution, adjust the pH value of the system to 7.39, add 0.2 g of hexadecyltrimethylammonium bromide and 1 g of tetrapropylammonium hydroxide and mix them evenly, while keeping stirring, slowly add 11.7 g of sodium permanganate, filter and wash the system after the reaction is complete, keep the temperature at 65 °C for 22 h, and dry the product to obtain a silicon-based precursor;

[0090] 2) The silicon-based precursor is evenly distributed on the carrier, 0.5 mL of water is added per gram of silicon-based precursor, the device is sealed for water vapor-assisted crystallization, and the crystallization is carried out at a constant temperature of 160 ° C for 24 h. After the device is cooled to room temperature, the product is washed and dried to obtain a silicon-based adsorbent, 0.3 mL of saturated copper nitrate solution is added to the silicon-based adsorbent per gram of silicon-based adsorbent and mixed evenly, and it is ultrasonically treated for 4 h. After washing and drying, the product is placed at 650 ° C and kept at a constant temperature for 4 h to obtain a composite purification material.

[0091] The composite purification material prepared in this example was subjected to the same performance test as in Example 1, and the results are as follows.

[0092]

[0093] Compared with Example 2, the material in this example is prone to cracking, which shows that the aging temperature conditions have an impact on the structural stability. Too high an aging temperature will cause the structure to be destroyed when the material is not fully formed. According to the results in the table, due to the insufficient combination of Si and manganese oxide, the mesoporous stability deteriorates, and the skeleton is prone to cracking, resulting in the deterioration of the adsorption performance of the material. In addition, the attenuation rate of the adsorption performance of the material is large, which shows that the aging conditions of the material should be limited. At the same time, the regeneration also shows different trends. The product obtained in this example is far inferior to other samples in the heat treatment regeneration process.

[0094] Comparative Example 4: A high-quality formaldehyde-removing air purification material with the same Si-based copper-manganese composite system available on the market was characterized in the same way as in Example 1. The characterization results are shown below.

[0095]

[0096] From the above characterization results and in comparison with the product of the present invention, it can be seen that the product of the present invention has very significant advantages under humid air and extreme humidity conditions. For existing air purification materials, high humidity will greatly increase the difficulty of adsorbing formaldehyde and increase the difficulty of transporting formaldehyde inside them, resulting in their actual effective catalytic degradation ability being greatly limited, which may completely change their adsorption-catalysis-release process. The present invention achieves the coordination of formaldehyde adsorption-degradation-release and improves the transportation efficiency of formaldehyde inside the material by constructing an orderly large-small pore combination to form a multi-level / multi-layer composite pore structure, which is very helpful in avoiding the adverse effects of high humidity on air purification materials. Even with the help of high humidity and multi-level pore coordination, it can form conditions that are conducive to the transportation of formaldehyde inside the material system, greatly improving the formaldehyde adsorption and catalytic degradation effects under high humidity conditions.

Claims

1. A method for preparing a composite purification material, characterized in that: The method comprises: 1) Take silicate and solvent and mix them evenly, adjust the pH value and add surfactant and structure directing agent to mix evenly, keep stirring and add manganate, after the reaction is complete, filter, wash, age and dry the system to obtain a silicon-based precursor; 2) The silicon-based precursor is heated and crystallized, and after cooling, the product is washed and dried to obtain a silicon-based adsorbent, the silicon-based adsorbent and the copper salt solution are evenly mixed and then subjected to ultrasonic treatment, and the composite purification material is obtained after washing, drying and high-temperature treatment; Step 1) the silicate is sodium silicate, and the modulus of the sodium silicate is 1; Step 1) The solvent is water, and the amount used is 15-35 mL / g silicate; Step 1) The pH value is adjusted to 7.35-7.44; Step 1) The surfactant is hexadecyltrimethylammonium bromide, and the amount used is 0.02-0.03 g / g silicate; Step 1) the structure directing agent is tetrapropylammonium hydroxide, and the amount thereof is 0.1 to 0.15 g / g silicate; Step 1) the manganate is sodium permanganate, and the amount thereof is 1.17-1.28 g / g silicate; Step 2) The heating crystallization process is: The silicon-based precursor is evenly distributed on the carrier, 0.5-0.8 mL of water is added per gram of silicon-based precursor, and the device is sealed for water vapor-assisted crystallization, and the temperature is kept constant at 155-165 °C for 23.5-24.5 h.

2. The method for preparing a composite purification material according to claim 1, characterized in that: The aging in step 1) is carried out at a constant temperature of 45 to 50°C for 20 to 22 hours.

3. The method for preparing a composite purification material according to claim 1, characterized in that: Step 2) The copper salt solution is a saturated copper nitrate solution, and its dosage is 0.3-0.5 mL / g silicon-based adsorbent.

4. The method for preparing a composite purification material according to claim 1 or 3, characterized in that: Step 2) The duration of the ultrasonic treatment is 4 to 5 hours; Step 2) The high temperature treatment is carried out at 600-650°C for 4-4.5 hours.

5. A composite purification material obtained by the method according to any one of claims 1 to 4.

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