Voc adsorbents and methods of making same

Abstract

The application provides a VOCs adsorbent and a preparation method thereof. The method comprises the following steps: preparing 13X molecular sieve by using waste catalyst as raw material, soaking the 13X molecular sieve in a cerium salt solution for ion exchange, soaking in an alkaline aqueous solution for first calcination, soaking in a silane alcohol solution for second calcination, and obtaining the VOCs adsorbent; wherein the waste catalyst comprises one or more of waste Z-5 molecular sieve catalyst, waste MTO catalyst, waste molecular sieve adsorbent, fly ash, waste FCC catalyst and waste VOC adsorbent. The introduced cerium ions can effectively increase the specific surface area and pore volume of the molecular sieve, so that the adsorption capacity of the adsorbent to VOCs is significantly improved; the introduction of cerium ions also promotes the formation of more active sites, further enhances the adsorption performance, and the prepared VOCs adsorbent can effectively utilize waste catalyst resources, has low preparation cost, and has excellent physical and chemical properties and environmental adaptability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of molecular sieve, in particular to a VOCs adsorbent and a preparation method thereof. BACKGROUND

[0002] Molecular sieve is a kind of silicate, which has the characteristics of uniform pore size, regular crystal structure, rich pore system, large specific surface area and good thermal stability. Therefore, it is considered as the preferred adsorbent material for removing oxygen-containing compounds in olefins. The pore size of FAU type (X, Y type) molecular sieve is about 0.74 nanometers. In particular, X type molecular sieve shows good effect in removing oxygen-containing compound impurities in olefins, and has been widely used in industrial practice.

[0003] 13X molecular sieve has a uniform and ordered microporous structure, which enables it to achieve precise molecular selection. The size and shape of the micropore can highly specifically adsorb molecules of a certain size and shape, while excluding other molecules, which has very important value in the separation and purification process in the chemical industry. Secondly, the large specific surface area provides more active adsorption sites, increasing the adsorption capacity of 13X molecular sieve. This means that in the same physical volume, 13X molecular sieve can adsorb more substances, thereby improving the processing rate and efficiency. This property is particularly important in the fields of liquid or gas purification, catalyst carriers and storage media.

[0004] Therefore, 13X molecular sieve has the characteristics of uniform and ordered micropore, large specific surface area and large pore volume, which not only shows great potential in traditional chemical, petroleum and natural gas processing fields, but also demonstrates broad application prospects in emerging fields such as environmental protection, clean energy and life science. For example, in industrial waste gas treatment, 13X molecular sieve can effectively remove harmful gases and volatile organic compounds (VOCs); in the production of pharmaceuticals and fine chemicals, it can be used to improve the purity and yield of products.

[0005] With the intensification of industrialization, the emission of VOCs in the air is increasing, which poses a serious threat to human health and the environment. Common VOCs removal techniques include adsorption method, catalytic combustion method, etc. Among them, the adsorption method is widely used because of its simple operation and low cost. 13X molecular sieve, due to its good thermal stability and large pore size, has become the preferred adsorbent for VOCs removal. However, the preparation cost of traditional 13X molecular sieve is relatively high, and its adsorption efficiency for VOCs still has room for improvement. SUMMARY

[0006] The main purpose of the present application is to provide a VOCs adsorbent and a preparation method thereof, in order to solve the problems of high cost and low adsorption efficiency of VOCs adsorbent in the prior art.

[0007] In order to achieve the above-mentioned purpose, according to one aspect of the present application, a preparation method of a VOCs adsorbent is provided, comprising the following steps: step S1, preparing 13X molecular sieve with waste catalyst as raw material; step S2, soaking the 13X molecular sieve in cerium salt solution, carrying out ion exchange reaction, and drying to obtain cerium-doped molecular sieve; step S3, soaking the cerium-doped molecular sieve in aqueous alkali solution, and then carrying out first calcination to obtain expanded pore molecular sieve; step S4, soaking the expanded pore molecular sieve in alcohol solution of silane, and then carrying out second calcination to obtain VOCs adsorbent; wherein the waste catalyst comprises one or more of waste Z-5 molecular sieve catalyst, waste MTO catalyst, waste molecular sieve adsorbent, fly ash, waste FCC catalyst and waste VOC adsorbent.

[0008] Further, the cerium salt solution comprises cerium nitrate solution and / or cerium sulfate solution, and the molar concentration is 0.4-0.6 mol / L; and / or the aqueous alkali solution comprises sodium hydroxide aqueous solution and / or potassium hydroxide aqueous solution, and the molar concentration is 1.5-2.5 mol / L; and / or in the alcohol solution of silane, the volume ratio of silane to alcohol is 1:(8.5-9.5); preferably, the silane comprises one or more of trimethylsilane, ethyl triethoxysilane and triisopropylsilane, and the alcohol comprises one or more of methanol, ethanol and isopropanol.

[0009] Further, the ion exchange time of step S2 is 22-26 hours; and / or the soaking time of step S3 is 1.5-2.5 hours; and / or the soaking time of step S4 is 10-14 hours.

[0010] Further, the drying condition is: drying at 100-120℃ for 10-14 hours; and / or the first calcination condition is: calcining at 450-550℃ for 3-5 hours; and / or the second calcination condition is: calcining at 550-650℃ for 2-4 hours.

[0011] Further, in step S1, the waste catalyst is subjected to aluminum dissolution and silicon dissolution treatment to obtain a silicon-rich liquid and an aluminum-rich liquid, the silicon-rich liquid and the aluminum-rich liquid are mixed to obtain a gel-like mother liquor, 5-20wt% of crystal seeds are added to the gel-like mother liquor, and then aging treatment and crystallization treatment are carried out in sequence, and the 13X molecular sieve is obtained after drying.

[0012] Further, the dissolving aluminum comprises: mixing the waste catalyst with NaCO3, calcining at 550-800℃ for 60-120min, then dissolving the calcined product with monobasic acid with mass concentration of 10-35%, filtering to obtain the aluminum-rich liquid and aluminum-dissolving residue; preferably, the mass ratio of the waste catalyst to NaCO3 is 1:(0.5-1:5); and / or the dissolving silicon comprises: mixing the aluminum-dissolving residue with NaOH, H2O, filtering to obtain the silicon-rich liquid; preferably, the mass ratio of the aluminum-dissolving residue to NaOH, H2O is (2-100):(40-60):(50-400).

[0013] Further, the aging condition is 20-100℃ for 0.1-24h; and / or the crystallization condition is 60-105℃ for 0.1-36h.

[0014] Further, the seed crystal is prepared by the following method: mixing a silicon source and water to obtain a silicon-containing material; mixing an aluminum source and water to obtain an aluminum-containing material; dropping the aluminum-containing material into the silicon-containing material, stirring at 20-100℃ for 0.1-24h to obtain a mixture gel; adjusting the pH value of the mixture gel to 8.5-12.5, crystallizing at 20-60℃ for 4-24h, then crystallizing at 80-120℃ for 6-48h to obtain the seed crystal; preferably, the silicon source comprises one or more of silica sol, tetraethyl orthosilicate, coarse-pored silica gel, silicon powder, fly ash and white carbon black; the aluminum source comprises one or more of sodium aluminate, pseudo-boehmite, aluminum sulfate and aluminum nitrate.

[0015] Further, the molar ratio of each component in the gel-like mother liquor is: SiO2 / Al2O3=(0.5-6.0):1, Na2O / SiO2=(0.5-6.0):1, H2O / SiO2=(10-100):1; and / or the molar ratio of each component in the seed crystal is: SiO2 / Al2O3=(0.1-2.5):1, Na2O / SiO2=(0.1-4.0):1, H2O / SiO2=(1.0-40.0):1; and / or the silicon-aluminum ratio of the 13X molecular sieve is 2.2-2.9, the pore volume is 0.3-0.5cm 3 / g, and the specific surface area is 700-950m 2 / g.

[0016] According to another aspect of the present application, there is provided a VOCs adsorbent obtained by the above-mentioned preparation method.

[0017] The application has the advantages that: the spent catalyst is used as raw material to prepare 13X molecular sieve, then cerium ions are introduced into the molecular sieve through ion exchange, and then the molecular sieve is treated by alkali and high-temperature calcination to expand the pore of the molecular sieve, and finally siloxane groups are introduced through silanization treatment to form a durable surface coating on the surface of the molecular sieve. The introduced cerium ions can effectively increase the specific surface area and pore volume of the molecular sieve, so that the adsorption capacity of the adsorbent for VOCs is significantly improved; the introduction of cerium ions also promotes the formation of more active sites, further enhancing the adsorption performance. The VOCs adsorbent prepared by the method can effectively utilize the resources of waste catalysts, has low preparation cost, and has excellent physical and chemical properties and environmental adaptability, and is suitable for environmental protection applications in many fields, especially industrial emission and indoor air purification, and provides an efficient and environmentally friendly solution for effectively controlling and reducing VOCs pollution. DETAILED DESCRIPTION

[0018] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments.

[0019] As described in the background art, the prior art has the problems of high cost and low adsorption efficiency of VOCs adsorbent. In order to solve the above problems, in a typical embodiment of the present application, a preparation method of VOCs adsorbent is provided, comprising the following steps: step S1, preparing 13X molecular sieve with spent catalyst as raw material; step S2, soaking the 13X molecular sieve in a cerium salt solution to perform ion exchange reaction, and drying to obtain cerium-doped molecular sieve; step S3, soaking the cerium-doped molecular sieve in an aqueous alkali solution, and then performing first calcination to obtain expanded pore molecular sieve; step S4, soaking the expanded pore molecular sieve in an alcohol solution of silane, and then performing second calcination to obtain VOCs adsorbent; wherein the spent catalyst includes one or more of waste Z-5 molecular sieve catalyst, waste MTO catalyst, waste molecular sieve adsorbent, fly ash, waste FCC catalyst and waste VOC adsorbent.

[0020] Specifically, one or more of waste Z-5 molecular sieve catalyst, waste MTO catalyst, waste molecular sieve adsorbent, fly ash, waste FCC catalyst and waste VOC adsorbent is used as raw material to prepare 13X molecular sieve; then the 13X molecular sieve is soaked in a cerium salt solution to perform ion exchange reaction, and cerium ions are introduced into the molecular sieve, and after drying, cerium-doped molecular sieve is obtained, and the doping of cerium can effectively increase the specific surface area and pore volume of the molecular sieve, so that the adsorption capacity of the adsorbent for VOCs is significantly improved; the introduction of cerium ions also promotes the formation of more active sites, further enhancing the adsorption performance.

[0021] Then the cerium-doped molecular sieve is soaked in an aqueous alkali solution, and then subjected to a first calcination to treat the molecular sieve to enlarge the pore structure of the molecular sieve, thereby obtaining an enlarged-pore molecular sieve; finally, the enlarged-pore molecular sieve is soaked in an alcoholic solution of silane, and then subjected to a second calcination, thereby introducing siloxane groups to form a durable surface coating on the surface of the molecular sieve, thereby obtaining the VOCs adsorbent.

[0022] The VOCs adsorbent prepared by the method has low preparation cost and excellent physicochemical properties and environmental adaptability, and is suitable for environmental protection applications in multiple fields, in particular, industrial emission and indoor air purification, thereby providing an efficient and environmentally friendly solution for effectively controlling and reducing VOCs pollution.

[0023] In a preferred embodiment, the cerium salt solution comprises a cerium nitrate solution and / or a cerium sulfate solution, and the molar concentration is 0.4-0.6 mol / L; and / or the aqueous alkali solution comprises a sodium hydroxide aqueous solution and / or a potassium hydroxide aqueous solution, and the molar concentration is 1.5-2.5 mol / L; and / or in the alcoholic solution of silane, the volume ratio of silane to alcohol is 1:(8.5-9.5); preferably, the silane comprises one or more of trimethylsilane, ethyl triethoxysilane and triisopropylsilane, and the alcohol comprises one or more of methanol, ethanol and isopropanol. The above materials can more fully achieve the doping of cerium, the enlargement of the pore structure and the generation of the silane-based surface coating, thereby further improving the adsorption performance of the VOCs adsorbent while reducing the preparation cost.

[0024] Based on similar reasons, in a preferred embodiment, the ion exchange time in step S2 is 22-26 hours; and / or the soaking time in step S3 is 1.5-2.5 hours; and / or the soaking time in step S4 is 10-14 hours.

[0025] Based on similar reasons, in a preferred embodiment, the drying conditions are: drying at 100-120℃ for 10-14 hours; and / or the first calcination conditions are: calcination at 450-550℃ for 3-5 hours; and / or the second calcination conditions are: calcination at 550-650℃ for 2-4 hours.

[0026] The 13X molecular sieve can be prepared from the waste catalyst using conventional methods in the art. For the purpose of further increasing the utilization rate of the waste catalyst, in a preferred embodiment, in step S1, the waste catalyst is subjected to aluminum dissolution and silicon dissolution to obtain a silicon-rich liquid and an aluminum-rich liquid, and the silicon-rich liquid and the aluminum-rich liquid are mixed to obtain a gel-like mother liquor; then, 5-20 wt% of the gel-like mother liquor is added with seed crystals, and then subjected to aging treatment and crystallization treatment in sequence, and dried to obtain the 13X molecular sieve.

[0027] In a preferred embodiment, the dissolving aluminum comprises: mixing the waste catalyst with NaCO3, calcining at 550-800°C for 60-120 min, then dissolving the calcined product with monobasic acid with a mass concentration of 10-35%, filtering to obtain an aluminum-rich liquid and aluminum-dissolving filter residue; preferably, the mass ratio of the waste catalyst to NaCO3 is 1:(0.5-1:5); and / or the dissolving silicon comprises: mixing the aluminum-dissolving filter residue with NaOH, H2O, filtering to obtain a silicon-rich liquid; preferably, the mass ratio of the aluminum-dissolving filter residue to NaOH, H2O is (2-100):(40-60):(50-400). Under the above conditions, the active elements such as silicon and aluminum in the waste catalyst can be more fully recovered, thereby further reducing the preparation cost of the VOCs adsorbent.

[0028] To better promote the generation of the structure of the 13X molecular sieve, in a preferred embodiment, the aging conditions are: aging at 20-100°C for 0.1-24h; and / or the crystallization conditions are: crystallizing at 60-105°C for 0.1-36h.

[0029] In a preferred embodiment, the seed crystal is prepared by the following method: mixing a silicon source and water to obtain a silicon-containing material; mixing an aluminum source and water to obtain an aluminum-containing material; adding the aluminum-containing material dropwise to the silicon-containing material, stirring at 20-100°C for 0.1-24h to obtain a mixture gel; adjusting the pH value of the mixture gel to 8.5-12.5, preferably 11.9-12.1, crystallizing at 20-60°C for 4-24h, and then crystallizing at 80-120°C for 6-48h to obtain the seed crystal; preferably, first crystallizing at 35-45°C for 11-13h; then crystallizing at 90-100°C for 22-26h.

[0030] Preferably, the silicon source comprises one or more of silica sol, tetraethyl orthosilicate, coarse-pore silica gel, silicon powder, fly ash, and white carbon black; the aluminum source comprises one or more of sodium aluminate, pseudo-boehmite, aluminum sulfate, and aluminum nitrate; and / or the mixing process of the silicon source and water is generally stirring at 20-60°C for 0.1-12h, and the stirring speed is maintained at 200-800rpm; the mixing process of the aluminum source and water is generally stirring at 20-60°C for 0.1-12h, and the stirring speed is preferably maintained at 200-800rpm, the mass concentration of the silicon-containing material is 28-99wt%, and the mass concentration of the aluminum-containing material is 15-99wt%. And / or in step S12, the stirring temperature is 20-100°C, and the stirring time is 0.1-24h. By precisely controlling the pH value, the temperature and time of the two-stage crystallization, and the raw material ratio, and by utilizing the synergistic effect, the pore volume and specific surface area of the seed crystal can be better controlled, which is more conducive to preparing molecular sieves with appropriate pore volume and specific surface area according to needs.

[0031] Most preferably, the pH value of the mixture gel is adjusted to 12, crystallized at 40℃ for 12h, then crystallized at 95℃ for 24h, to obtain the molar ratio of each component in the crystal seed: SiO2 / Al2O3=4.7:1, Na2O / SiO2=1.95:1, H2O / SiO2=44:1, which collectively controls the uniform arrangement of pores, the size of the specific surface area, and the pore volume, to prepare the molecular sieve crystal seed with the most excellent performance.

[0032] In a preferred embodiment, the molar ratio of each component in the gel-like mother liquor is: SiO2 / Al2O3=(0.5-6.0):1, Na2O / SiO2=(0.5-6.0):1, H2O / SiO2=(10-100):1; and / or the molar ratio of each component in the crystal seed is: SiO2 / Al2O3=(0.1-2.5):1, Na2O / SiO2=(0.1-4.0):1, H2O / SiO2=(1.0-40.0):1; and / or the silicon-aluminum ratio of the 13X molecular sieve is 2.2-2.9, the pore volume is 0.3-0.5cm 3 / g, and the specific surface area is 700-950m 2 / g. The above conditions are more conducive to laying the foundation for preparing the 13X molecular sieve with excellent adsorption performance, so that the prepared 13X molecular sieve has controllable micro-mesopore specific surface area and large pore volume, high hydrothermal stability, wide silicon-aluminum ratio range, and controllable morphology, thereby further improving the adsorption performance of the VOCs adsorbent.

[0033] In another typical embodiment of the present application, a VOCs adsorbent is also provided, which is obtained by the preparation method described above, and has low preparation cost and good adsorption performance.

[0034] The present application will be further described in detail below in combination with specific examples, which cannot be understood as limiting the scope of the present application.

[0035] Example 1

[0036] Seed preparation: 21.0 g of silica sol (mass fraction 30%) was dissolved in 36.0 g of deionized water, and after pretreatment at 25°C and 500 rpm for 1 h in a closed reaction kettle, a dispersion phase aqueous solution of the silicon source was obtained; 24 g of aluminum sulfate was dissolved in 18.0 g of deionized water, and after stirring at 25°C and 500 rpm for 1 h, an aqueous dispersion phase solution of the aluminum source was obtained; the aqueous solution of the aluminum source was slowly added to the aqueous solution of the silicon source, and after continuing to stir at 60°C for 8 h, a gel solution was obtained; 6.74 g of sodium hydroxide was dissolved in 36 g of a deionized water dispersion and added to the gel solution, and the pH value was controlled to be maintained at 12.2, and the gel solution was placed in a hydrothermal reaction kettle for two-stage temperature control crystallization, the first-stage crystallization temperature was 40°C, and the time was 12 h, and the second-stage crystallization temperature was 95°C, and the time was 24 h, and deionized water was added as needed during the crystallization process, and a seed solution was obtained.

[0037] Step S1, the waste Z-5 molecular sieve catalyst was mixed with NaCO3 according to a mass ratio of 1:1, calcined at 700°C for 90 min, and then the calcined product was dissolved with a monobasic acid with a mass concentration of 20%, filtered to obtain an aluminum-rich liquid and an aluminum-dissolved filter residue; the aluminum-dissolved filter residue was mixed with NaOH, H2O according to a mass ratio of 50:50:200, and filtered to obtain a silicon-rich liquid; the silicon-rich liquid and the aluminum-rich liquid were mixed to obtain a gel-like mother liquor; a certain mass ratio of seed crystals was added to the gel-like mother liquor, and then aging treatment and crystallization treatment were sequentially performed, the aging temperature was 60°C, and the time was 12 h; the crystallization temperature was 80°C, and the time was 18 h, and after drying, 13X molecular sieves were obtained;

[0038] Step S2, 50 g of 13X molecular sieves were dried at 80°C for 12 hours to remove residual moisture; the dried 13X molecular sieves were soaked in 250 mL of 0.5 mol / L cerium nitrate (Ce(NO3)3) solution for 24 hours of ion exchange reaction; then the molecular sieves were dried at 110°C for 12 hours to obtain cerium-doped molecular sieves;

[0039] Step S3, the cerium-doped molecular sieves were soaked in a 2 mol / L sodium hydroxide (NaOH) solution for 2 hours, and then calcined at 500°C for 4 hours under air to obtain a pore-enlarged molecular sieve;

[0040] Step S4, the pore-enlarged molecular sieves were soaked in a mixed solution containing 50 mL of ethyl triethoxysilane (TEOS) and 450 mL of ethanol for 12 hours, and then dried again and calcined at 600°C for 3 hours to obtain a VOCs adsorbent.

[0041] Example 2

[0042] The difference from Example 1 is that,

[0043] Seed preparation: 1 g of silicon powder was dissolved in 18 g of deionized water, and a dispersion phase aqueous solution of a silicon source was obtained after pretreatment in a closed reaction kettle at 25℃ and 500 rpm for 1 hour. 12 g of aluminum nitrate was dissolved in 18.0 g of deionized water, and a dispersion phase aqueous solution of an aluminum source was prepared by stirring at 35℃ and 500 rpm for 1 hour. The prepared aqueous solution of the aluminum source was slowly added to the aqueous solution of the silicon source, and a gel solution was prepared by continuing to stir at 50℃ for 6 hours. 2 g of sodium hydroxide was dissolved in 36 g of deionized water to prepare a dispersion liquid, which was slowly added to the gel solution to control the pH value at 11.8. Then, the mixed gel solution was transferred to a hydrothermal reaction kettle, and a two-stage temperature control crystallization process was performed: the first stage crystallization temperature was set to 50℃, and the duration was 14 hours; the second stage crystallization temperature was controlled at 100℃, and the maintenance time was 18 hours. Deionized water was added as needed during the crystallization process to obtain a seed solution.

[0044] Example 3

[0045] The difference from Example 1 is that,

[0046] Seed preparation: 1 g of silicon powder was dissolved in 18 g of deionized water, and a dispersion phase aqueous solution of a silicon source was obtained after pretreatment in a closed reaction kettle at 25℃ and 500 rpm for 1 hour. 12 g of aluminum nitrate was dissolved in 18.0 g of deionized water, and a dispersion phase aqueous solution of an aluminum source was prepared by stirring at 35℃ and 500 rpm for 1 hour. The prepared aqueous solution of the aluminum source was slowly added to the aqueous solution of the silicon source, and a gel solution was prepared by continuing to stir at 50℃ for 6 hours. 2 g of sodium hydroxide was dissolved in 36 g of deionized water to prepare a dispersion liquid, which was slowly added to the gel solution to control the pH value at 11.8. Then, the mixed gel solution was transferred to a hydrothermal reaction kettle, and a two-stage temperature control crystallization process was performed: the first stage crystallization temperature was set to 50℃, and the duration was 14 hours; the second stage crystallization temperature was controlled at 100℃, and the maintenance time was 18 hours. Deionized water was added as needed during the crystallization process to obtain a seed solution.

[0047] Step S1, mix the waste FCC catalyst with NaCO3 according to the mass ratio of 1:0.5, calcine at 550℃ for 120min, then dissolve the calcined product with monobasic acid with a mass concentration of 10%, filter to obtain an aluminum-rich liquid and an aluminum-dissolved filter residue; mix the aluminum-dissolved filter residue with NaOH and H2O according to the mass ratio of 2:40:50, filter to obtain a silicon-rich liquid; mix the silicon-rich liquid and the aluminum-rich liquid to obtain a gel-like mother liquor; add a certain mass ratio of seed crystals to the gel-like mother liquor, then sequentially perform aging treatment and crystallization treatment, the aging temperature is 20℃, and the time is 24h; the crystallization temperature is 60℃, and the time is 36h, and after drying, 13X molecular sieve is obtained.

[0048] Example 4

[0049] The difference from example 1 is that

[0050] Seed preparation: 14.65 g of tetraethyl orthosilicate was mixed with 36 g of deionized water, and after pretreatment at 25℃ and 800 rpm for 1 hour in a closed reaction kettle, a dispersion phase aqueous solution of the silicon source was obtained; 12 g of aluminum nitrate was dissolved in 18.0 g of deionized water, and stirred at 35℃ and 800 rpm for 1 hour to obtain a dispersion phase aqueous solution of the aluminum source. The aluminum source solution was gradually added to the silicon source solution, and mixed and stirred at 20℃ for 0.1 hours to obtain a gel solution; 0.56 g of sodium hydroxide was dissolved in 6 g of deionized water as a dispersion liquid, and slowly poured into the gel solution to maintain a pH value of 8.5, and the prepared gel was introduced into a hydrothermal reaction kettle to perform a staged crystallization reaction: first set the crystallization temperature to 20℃ for 4 hours; then raised to 80℃ and kept crystallization for 6 hours, and deionized water was added as needed during the crystallization process to obtain a seed solution.

[0051] Step S1, mix the waste molecular sieve adsorbent with NaCO3 according to the mass ratio of 1:1.5, calcine at 800℃ for 60min, then dissolve the calcined product with monobasic acid with a mass concentration of 35%, filter to obtain an aluminum-rich liquid and an aluminum-dissolved filter residue; mix the aluminum-dissolved filter residue with NaOH, H2O according to the mass ratio of 100:60:400, filter to obtain a silicon-rich liquid; mix the silicon-rich liquid and the aluminum-rich liquid to obtain a gel-like mother liquor; add a certain mass ratio of seed crystals to the gel-like mother liquor, then sequentially perform aging treatment and crystallization treatment, the aging temperature is 100℃, and the time is 0.1h; the crystallization temperature is 105℃, and the time is 0.1h, and after drying, 13X molecular sieve is obtained.

[0052] Example 5

[0053] The difference from example 1 is that in step S2, 50g of 13X molecular sieve is dried at 80℃ for 12 hours to remove residual water; the dried 13X molecular sieve is soaked in 250mL of 0.4mol / L cerium sulfate solution for 26 hours of ion exchange reaction; then the molecular sieve is dried at 100℃ for 14 hours to obtain a cerium-doped molecular sieve.

[0054] Example 6

[0055] The difference from example 1 is that in step S2, 50g of 13X molecular sieve is dried at 80℃ for 12 hours to remove residual water; the dried 13X molecular sieve is soaked in 250mL of 0.6mol / L cerium sulfate solution for 22 hours of ion exchange reaction; then the molecular sieve is dried at 120℃ for 10 hours to obtain a cerium-doped molecular sieve.

[0056] Example 7

[0057] The difference from Example 1 is that in step S3, the cerium-doped molecular sieve is soaked in a 1.5 mol / L potassium hydroxide solution for 2.5 hours, and then calcined at 450℃ for 5 hours under air to obtain the expanded pore molecular sieve.

[0058] Example 8

[0059] The difference from Example 1 is that in step S3, the cerium-doped molecular sieve is soaked in a 2.5 mol / L potassium hydroxide solution for 1.5 hours, and then calcined at 550℃ for 3 hours under air to obtain the expanded pore molecular sieve.

[0060] Example 9

[0061] Seed preparation: 21.0 g of silica sol (30% by mass) was dissolved in 36.0 g of deionized water to obtain a dispersion phase aqueous solution of the silicon source; 24 g of aluminum sulfate was dissolved in 18.0 g of deionized water to obtain a dispersion phase aqueous solution of the aluminum source; the aqueous solution of the aluminum source was slowly added to the aqueous solution of the silicon source, and stirring was continued at 60℃ for 8 h to obtain a gel solution; 6.74 g of sodium hydroxide was dissolved in 36 g of a deionized water dispersion and added to the gel solution to control the pH value to maintain 12.2, and the gel solution was placed in a hydrothermal reaction kettle for two-stage temperature control crystallization, the first stage crystallization temperature was 40℃, and the time was 12 hours, the second stage crystallization temperature was 95℃, and the time was 24 hours, and deionized water was added as needed during the crystallization process to obtain a seed solution.

[0062] Step S1, the waste Z-5 molecular sieve catalyst was mixed with NaCO3 according to a mass ratio of 1:1, calcined at 700℃ for 90 min, and then dissolved with a monobasic acid with a mass concentration of 20%, and filtered to obtain an aluminum-rich liquid and an aluminum-dissolved filter residue; the aluminum-dissolved filter residue was mixed with NaOH and H2O according to a mass ratio of 50:50:200, and filtered to obtain a silicon-rich liquid; the silicon-rich liquid and the aluminum-rich liquid were mixed to obtain a gel-like mother liquor; a certain mass ratio of seed crystals was added to the gel-like mother liquor, and then aging treatment and crystallization treatment were sequentially performed, the aging temperature was 60℃, and the time was 12 h; the crystallization temperature was 80℃, and the time was 18 h, and after drying, a 13X molecular sieve was obtained;

[0063] Step S2, 50 g of the 13X molecular sieve was dried at 80℃ for 12 hours to remove residual water; the dried 13X molecular sieve was soaked in 250 mL of a 0.5 mol / L cerium nitrate (Ce(NO3)3) solution for an ion exchange reaction for 24 hours; and then the molecular sieve was dried at 110℃ for 12 hours to obtain a cerium-doped molecular sieve;

[0064] Step S3, the cerium-doped molecular sieve is soaked in a 2 mol / L sodium hydroxide (NaOH) solution for 2 hours, and then calcined at 500°C for 4 hours under air to obtain a pore-expanded molecular sieve;

[0065] Step S4, the pore-expanded molecular sieve is soaked in a mixed solution containing 50 mL of trimethylsilane and 425 mL of methanol for 14 hours, and then calcined at 550°C for 4 hours after drying again to obtain a VOCs adsorbent.

[0066] Example 10

[0067] Seed preparation: 21.0 g of silica sol (30% by mass) is dissolved in 36.0 g of deionized water, and a dispersion phase aqueous solution of a silicon source is obtained after pretreatment at 25°C and 500 rpm for 1 hour in a closed reaction kettle; 24 g of aluminum sulfate is dissolved in 18.0 g of deionized water, and a dispersion phase aqueous solution of an aluminum source is obtained after stirring at 25°C and 500 rpm for 1 h; the aqueous solution of the aluminum source is slowly added to the aqueous solution of the silicon source, and a gel solution is obtained after continuing to stir at 60°C for 8 h; 6.74 g of sodium hydroxide is dissolved in a 36 g deionized water dispersion and added to the gel solution, and the pH value is controlled to maintain at 12.2, and the gel solution is placed in a hydrothermal reaction kettle for two-stage temperature control crystallization, the first-stage crystallization temperature is 40°C, and the time is 12 hours, and the second-stage crystallization temperature is 95°C, and the time is 24 hours, and deionized water is added as needed during the crystallization process to obtain a seed solution.

[0068] Step S1, the waste Z-5 molecular sieve catalyst is mixed with NaCO3 at a mass ratio of 1:1, calcined at 700°C for 90 min, and then dissolved with a monobasic acid with a mass concentration of 20%, filtered to obtain an aluminum-rich liquid and an aluminum-dissolved filter residue; the aluminum-dissolved filter residue is mixed with NaOH, H2O at a mass ratio of 50:50:200, filtered to obtain a silicon-rich liquid; the silicon-rich liquid and the aluminum-rich liquid are mixed to obtain a gel-like mother liquor; a certain mass ratio of seed crystals is added to the gel-like mother liquor, and then aging treatment and crystallization treatment are sequentially performed, the aging temperature is 60°C, and the time is 12 h; the crystallization temperature is 80°C, and the time is 18 h, and after drying, a 13X molecular sieve is obtained;

[0069] Step S2, 50 g of the 13X molecular sieve is dried at 80°C for 12 hours to remove residual water; the dried 13X molecular sieve is soaked in 250 mL of a 0.5 mol / L cerium nitrate (Ce(NO3)3) solution for 24 hours of ion exchange reaction; and then the molecular sieve is dried at 110°C for 12 hours to obtain a cerium-doped molecular sieve;

[0070] Step S3, the cerium-doped molecular sieve was soaked in a 2 mol / L sodium hydroxide (NaOH) solution for 2 hours, and then calcined at 500°C for 4 hours under air to obtain a pore-expanded molecular sieve;

[0071] Step S4, the pore-expanded molecular sieve was soaked in a mixed solution containing 50 mL of triisopropylsilane and 475 mL of isopropyl alcohol for 10 hours, and then calcined at 650°C for 2 hours after drying again to obtain a VOCs adsorbent.

[0072] Comparative Example 1

[0073] The difference from Example 1 is that step S2 is not performed.

[0074] The molar ratios of the components in the seed crystals and gel-like mother liquor of the above examples and comparative examples, and the performance test results of the 13X molecular sieve and the VOCs adsorbent are shown in Tables 1-2.

[0075] Test method:

[0076] Molar ratio, silicon-aluminum ratio: X-ray fluorescence spectroscopy (XRF);

[0077] Pore volume, specific surface area: BET test method;

[0078] Adsorption performance: fixed bed adsorption experiment: ethylene was used as the adsorption object, which was passed through a fixed bed containing the adsorbent, and the concentration change through the bed was monitored to determine the adsorption capacity as the weight of adsorbed ethylene (mg) / the weight of adsorbent (g), with the unit being mg / g.

[0079] Table 1

[0080]

[0081] Table 2

[0082]

[0083]

[0084] As can be seen from the above, compared with the comparative examples, each embodiment of the present application first utilizes the waste catalyst raw material to prepare 13X molecular sieve, then introduces cerium ions into the molecular sieve through ion exchange, and then performs pore expansion treatment on the molecular sieve through alkali treatment and high-temperature calcination, and finally introduces siloxane groups through silanization treatment to form a durable surface coating on the surface of the molecular sieve. Among them, the introduced cerium ions can effectively increase the specific surface area and pore volume of the molecular sieve, so that the adsorption capacity of the adsorbent to VOCs is significantly improved; the introduction of cerium ions also promotes the formation of more active sites, further enhancing the adsorption performance. The VOCs adsorbent prepared by the method of the present application can effectively utilize waste catalyst resources, has low preparation cost, and has excellent physicochemical properties and environmental adaptability, and is suitable for environmental protection applications in many fields, especially industrial emissions and indoor air purification, and provides an efficient and environmentally friendly solution for effectively controlling and reducing VOCs pollution. In addition, it can be seen that when each process parameter is within the preferred range of the present application, the comprehensive performance of the prepared catalyst is better.

[0085] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method of preparing a VOCs adsorbent, characterized by, The method comprises the following steps: S1, the waste catalyst is subjected to aluminum dissolution and silicon dissolution treatment to obtain a silicon-rich liquid and an aluminum-rich liquid, the silicon-rich liquid and the aluminum-rich liquid are mixed to obtain a gel-like mother liquor, seed crystals accounting for 5-20 wt% of the gel-like mother liquor are added to the gel-like mother liquor, and then aging treatment and crystallization treatment are sequentially performed, and after drying, 13X molecular sieves are obtained; the seed crystals are prepared by the following method: a silicon source and water are mixed to obtain a silicon-containing material; an aluminum source and water are mixed to obtain an aluminum-containing material; the aluminum-containing material is added dropwise to the silicon-containing material, stirred at 20-100°C for 0.1-24h, and a mixture gel is obtained; the pH value of the mixture gel is adjusted to 8.5-12.5, and crystallization is performed at 20-60°C for 4-24h, and then crystallization is performed at 80-120°C for 6-48h to obtain the seed crystals; S2, the 13X molecular sieves are soaked in a cerium salt solution to perform ion exchange reaction, and after drying, cerium-doped molecular sieves are obtained; S3, the cerium-doped molecular sieves are soaked in an aqueous alkali solution, and then first calcination is performed to obtain hole-expanding molecular sieves; S4, the hole-expanding molecular sieves are soaked in an alcohol solution of silane, and then second calcination is performed to obtain the VOCs adsorbent; The waste catalyst comprises one or more of waste MTO catalysts, waste molecular sieve adsorbents, waste FCC catalysts, and waste VOC adsorbents.

2. The method according to claim 1, wherein the cerium salt solution comprises a cerium nitrate solution and / or a cerium sulfate solution, and the molar concentration of the cerium salt solution is 0.4-0.6 mol / L; and / or the aqueous alkali solution comprises a sodium hydroxide aqueous solution and / or a potassium hydroxide aqueous solution, and the molar concentration of the aqueous alkali solution is 1.5-2.5 mol / L; and / or the volume ratio of the silane to the alcohol in the alcohol solution of silane is 1: (8.5-9.5). The silane comprises one or more of trimethylsilane, ethyl triethoxysilane, and triisopropylsilane, and the alcohol comprises one or more of methanol, ethanol, and isopropyl alcohol.

4. The method according to claim 1 or 2, wherein the ion exchange reaction time in S2 is 22-26 hours; and / or the soaking time in S3 is 1.5-2.5 hours; and / or the soaking time in S4 is 10-14 hours.

5. The method according to claim 1 or 2, wherein the drying conditions are: drying at 100-120°C for 10-14 hours; and / or the first calcination conditions are: calcination at 450-550°C for 3-5 hours; and / or the second calcination conditions are: calcination at 550-650°C for 2-4 hours.

3. The method of preparing a VOCs adsorbent according to claim 2, wherein, The aluminum dissolution comprises: mixing the waste catalyst with NaCO3, calcining at 550-800°C for 60-120min, then dissolving the calcination product with a monobasic acid with a mass concentration of 10-35%, and filtering to obtain an aluminum-rich liquid and aluminum dissolution residue. ​ ​ ​ ​ ​ ​ ​ ​ 6. The method of making a VOCs adsorbent of claim 1, wherein, ​ 7. The method of making a VOCs adsorbent of claim 6, wherein, The mass ratio of the waste catalyst to NaCO3 is 1:(0.5-1:5).

8. The method of making a VOCs adsorbent of claim 6, wherein, The dissolving silicon comprises mixing the aluminum-dissolving filter residue with NaOH and H2O, and filtering to obtain a silicon-rich liquid.

9. The method of making a VOCs adsorbent of claim 8, wherein, The mass ratio of the aluminum-dissolving filter residue to NaOH and H2O is (2-100):(40-60):(50-400).

10. The method of making a VOCs adsorbent of claim 1, wherein, The aging treatment is performed at 20-100°C for 0.1-24h, and / or the crystallization treatment after the aging treatment is performed at 60-105°C for 0.1-36h.

11. The method of making a VOCs adsorbent of claim 1, wherein, In the preparation of the seed crystal, the silicon source comprises one or more of silica sol, tetraethyl orthosilicate, coarse-pored silica gel, silicon powder, fly ash and white carbon black; and the aluminum source comprises one or more of sodium aluminate, pseudo-boehmite, aluminum sulfate and aluminum nitrate.

12. The method for preparing the VOCs adsorbent according to claim 1, wherein, The molar ratio of each component in the gel-like mother liquor is SiO2 / Al2O3=(0.5-6.0):1, Na2O / SiO2=(0.5-6.0):1 and H2O / SiO2=(10-100):1; and / or The molar ratio of each component in the seed crystal is SiO2 / Al2O3=(0.1-2.5):1, Na2O / SiO2=(0.1-4.0):1 and H2O / SiO2=(1.0-40.0):1; and / or The 13X molecular sieve has a silicon-aluminum ratio of 2.2-2.9, a pore volume of 0.3-0.5 cm 3 / g, and a specific surface area of 700-950 m 2 / g.

13. A VOCs adsorbent, characterized by, The method for preparing the VOCs adsorbent according to any one of claims 1-12.

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