Voc adsorbents and methods of making same

Abstract

The application provides a VOCs adsorbent and a preparation method thereof. The preparation method comprises the following steps: sequentially performing aluminum dissolution treatment and silicon dissolution treatment on waste molecular sieves to obtain an aluminum-rich liquid and a silicon-rich liquid; sequentially subjecting the aluminum-rich liquid, the silicon-rich liquid and seeds to gelation, aging and first hydrothermal crystallization to obtain 13X molecular sieves; sequentially immersing the 13X molecular sieves in a silanization reagent solution and a nickel-containing solution to obtain nickel-modified 13X molecular sieves; sequentially performing first hydrothermal reaction and calcination on the nickel-modified 13X molecular sieves and a titanium-silicon molecular sieve precursor solution to obtain core-shell structure 13X molecular sieves; performing ion exchange reaction on the core-shell structure 13X molecular sieves and a cerium ion solution, and then sequentially performing drying, alkali solution treatment and first calcination to obtain calcined 13X molecular sieves; and sequentially performing silanization modification and second calcination on the calcined 13X molecular sieves to obtain the VOCs adsorbent. The adsorbent prepared by the method has high VOCs adsorption efficiency.

Description

TECHNICAL FIELD

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

[0002] Molecular sieves are 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. Molecular sieves are considered to be 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 nm, and X type molecular sieve can better remove oxygen-containing compound impurities in olefins, so the research on X type molecular sieve is more, and X type molecular sieve has been widely used in industrial practice.

[0003] Firstly, the uniform and ordered microporous structure of 13X molecular sieve enables it to precisely screen molecules, among which the size and shape of micropores can highly specifically adsorb molecules of specific size and shape, while excluding other molecules, which is very valuable in the separation and purification process in the chemical industry. For example, in the field of gas separation, 13X molecular sieve can effectively separate target gases such as oxygen, nitrogen or carbon dioxide from a mixed gas stream. 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 feature is particularly important in the fields of liquid or gas purification, catalyst carriers, and storage media.

[0004] Therefore, 13X molecular sieve with uniform and ordered micropores, large specific surface area, large pore volume and other characteristics 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), and 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 due to its simple operation and low cost. 13X molecular sieve is the preferred adsorbent for VOCs removal due to its good thermal stability and large pore size. However, the adsorption efficiency of traditional 13X molecular sieve for VOCs still has room for improvement. SUMMARY

[0006] The present application aims to provide a VOCs adsorbent and a preparation method thereof to solve the problems of poor adsorption performance and low adsorption capacity of the VOCs adsorbent in the prior art.

[0007] To achieve the above-mentioned purpose, according to one aspect of the present application, a preparation method of a VOCs adsorbent is provided, which comprises the following steps: step S1, sequentially subjecting waste molecular sieves to aluminum dissolution treatment and silicon dissolution treatment to obtain an aluminum-rich liquid and a silicon-rich liquid; step S2, sequentially subjecting raw materials comprising the aluminum-rich liquid, the silicon-rich liquid and seed crystals to gelation treatment, aging treatment and first hydrothermal crystallization treatment to obtain 13X molecular sieves; step S3, sequentially subjecting the 13X molecular sieves to first impregnation treatment and second impregnation treatment in a silanization reagent solution and a nickel-containing solution to obtain nickel-modified 13X molecular sieves; step S4, sequentially subjecting a mixture comprising the nickel-modified 13X molecular sieves and a titanium silicalite molecular sieve precursor solution to first hydrothermal reaction and calcination treatment to obtain core-shell structure 13X molecular sieves; step S5, sequentially subjecting a cerium ion solution to ion exchange reaction with the core-shell structure 13X molecular sieves, and then subjecting the ion exchange product to drying, alkali solution treatment and first calcination treatment to obtain calcined 13X molecular sieves; and step S6, sequentially subjecting the calcined 13X molecular sieves to silanization modification treatment and second calcination treatment to obtain the VOCs adsorbent.

[0008] Further, in the step S3, the first impregnation treatment is performed for 8-24 h; and / or the second impregnation treatment is performed for 24-48 h; preferably, the molar concentration of the silanization reagent solution is 0.05-0.2 mol / L; and / or the molar concentration of the nickel-containing solution is 0.05-0.2 mol / L; preferably, the mass of the 13X molecular sieves to the volume of the silanization reagent solution is 400-600:1 g / L; preferably, the mass of the 13X molecular sieves to the volume of the nickel-containing solution is 400-600:1 g / L; preferably, the nickel-containing solution is a nickel nitrate solution and / or a nickel sulfate solution; preferably, the silanization reagent is selected from any one or more of 3-aminopropyltriethoxysilane, tetraethoxysilane and tetramethoxysilane; preferably, the step S3 further comprises: subjecting the 13X molecular sieves obtained after the second impregnation treatment to third calcination to obtain nickel-modified 13X molecular sieves coated with a layer of nickel nanoparticles; preferably, the third calcination is performed in a hydrogen atmosphere at a temperature of 500-600℃ for 2-4 h.

[0009] Further, in the step S4, the temperature of the first hydrothermal reaction is 150-200°C, and the time of the first hydrothermal reaction is 12-24h; preferably, the temperature of the calcination treatment is 450-550°C, and the time of the calcination treatment is 4-8h; the titanium-silicon molecular sieve precursor solution comprises a first silicon source, a titanium source, a template agent, a fluorine complex and water, wherein the first silicon source, the titanium source, the template agent, the fluorine complex and the water are mixed according to a molar ratio of 1:0.04-0.1:0.1-0.3:0.03-0.06:20-50; preferably, the mass of the nickel-modified 13X molecular sieve to the volume of the titanium-silicon molecular sieve precursor solution is 400-600:1g / L; preferably, the first silicon source is selected from any one or more of SiO2, Na2SiO3 and Si(OC2H5)4; preferably, the titanium source is selected from any one or more of TiO2, TiCl4 and Na2TiO3; preferably, the fluorine complex is selected from any one or more of sodium hexafluorophosphate, sodium hexafluoroacetyl acetonate and ammonium fluoride; and preferably, the template agent is an organic amine and / or a quaternary ammonium salt.

[0010] Further, in the step S5, the molar concentration of the cerium ion solution is 0.05-0.5mol / L in terms of cerium ions in the cerium ion solution, and preferably, the mass of the core-shell structure 13X molecular sieve to the volume of the cerium ion solution is 1-20:100g / mL; preferably, the cerium ion solution is selected from any one or more of cerium chloride, cerium nitrate, cerium citrate and cerium acetate; and / or the temperature of the ion exchange reaction is 45-60°C, and / or the time of the ion exchange reaction is 16-24h; preferably, the process of the alkali solution treatment comprises: performing a third impregnation treatment on the dried molecular sieve in an alkali solution, and preferably, the time of the third impregnation treatment is 1-3h; preferably, the alkali solution is NaOH and / or KOH; and preferably, the first calcination treatment is performed in an air atmosphere, and preferably, the temperature of the first calcination treatment is 400-600°C, and preferably, the time of the first calcination treatment is 5-8h.

[0011] Further, in the step S6, the time of the silylation modification treatment is 8-24h; preferably, the volume ratio of the silane reagent to the solvent is 1:5-10; preferably, the reagents used in the silylation modification treatment comprise the silane reagent and the solvent; preferably, the silane reagent is selected from any one or more of methyltrimethoxysilane, ethyltriethoxysilane and propenyltrimethoxysilane; preferably, the solvent is selected from any one or more of ethanol, propanol and butanol; and / or the temperature of the second calcination treatment is 500-700°C, and the time of the second calcination treatment is 2-4h.

[0012] Further, in the step S2, the 13X molecular sieve comprises silicon elements and aluminum elements, and the molar ratio of the silicon elements to the aluminum elements is 2.2-2.9:1; and / or the pore volume of the 13X molecular sieve is 0.3-0.5cm 3 / g, and / or the specific surface area of the 13X molecular sieve is 700-950 m 2 / g.

[0013] Further, the seed crystal contains SiO2, Al2O3, Na2O and H2O, wherein the molar ratio of SiO2 to Al2O3 is 0.01-2.5:1, and the molar ratio of Na2O, H2O to SiO2 is 0.01-4.0:1.0-40.0:1; and / or the molar ratio of SiO2 to Al2O3 is 4.6-5.0:1, and the molar ratio of Na2O, H2O to SiO2 is 1.8-2.0:40-50:1.

[0014] Further, the step S2 comprises: step S21, subjecting the aluminum-rich liquid and the silicon-rich liquid to gelation treatment to obtain a first gel; and step S22, sequentially subjecting the first gel and the seed crystal to aging treatment and first hydrothermal crystallization treatment to obtain the 13X molecular sieve; wherein the first gel contains SiO2, Al2O3, Na2O and H2O, wherein the molar ratio of SiO2 to Al2O3 is 0.5-6.0:1, and the molar ratio of Na2O, H2O to SiO2 is 0.5-6.0:10-100:1; preferably, the mass ratio of the seed crystal to the first gel is 5-20:100; and / or the temperature of the aging treatment is 20-100℃, and the time of the aging treatment is 0.1-24h; and / or the temperature of the first hydrothermal crystallization treatment is 60-105℃, and the time of the first hydrothermal crystallization treatment is 0.1-36h.

[0015] Further, the preparation method further comprises a preparation process of the seed crystal, the preparation process comprising: stirring and mixing raw materials comprising an aluminum source, a second silicon source and water to obtain a second gel; adjusting the pH value of the second gel to 8.5-12.5 and then performing a second hydrothermal crystallization treatment to obtain the seed crystal; wherein the stirring and mixing rate is 200-800 rpm, and / or the stirring and mixing temperature is 20-100℃, and / or the stirring and mixing time is 0.1-24 h; preferably, the pH value of the second gel is 11.8-12.2; preferably, the second silicon source is selected from any one or more of silica sol, tetraethyl orthosilicate, coarse-pore silica gel, silicon powder, fly ash and white carbon black; preferably, the aluminum source is selected from any one or more of sodium aluminate, pseudo-boehmite, aluminum sulfate and aluminum nitrate; preferably, the second hydrothermal crystallization treatment comprises a first-stage hydrothermal crystallization treatment and a second-stage hydrothermal crystallization treatment, wherein the first-stage hydrothermal crystallization treatment temperature is 20-60℃, and / or the first-stage hydrothermal crystallization treatment time is 4-24 h; preferably, the second-stage hydrothermal crystallization treatment temperature is 80-120℃, and / or the second-stage hydrothermal crystallization treatment time is 6-48 h; further preferably, the first-stage hydrothermal crystallization treatment temperature is 35-45℃, and / or the first-stage hydrothermal crystallization treatment time is 11-13 h; the second-stage hydrothermal crystallization treatment temperature is 90-100℃, and / or the second-stage hydrothermal crystallization treatment time is 22-26 h; the second-stage hydrothermal crystallization treatment temperature is 50-60℃ higher than the first-stage hydrothermal crystallization treatment temperature.

[0016] Further, the preparation method further comprises a pretreatment process of the waste molecular sieve, the pretreatment process comprising: performing a sintering treatment on a mixture comprising the waste molecular sieve and a sodium salt to obtain a sintered product; sequentially performing an aluminum dissolution treatment and a solid-liquid separation on the sintered product using an acidic solution to obtain an aluminum-rich liquid and a residue; sequentially performing a silicon dissolution treatment and a solid-liquid separation on the residue using an alkaline solution to obtain a silicon-rich liquid; wherein the mass ratio of the waste molecular sieve to the sodium salt is 1:0.5-5; and / or the sintering treatment temperature is 550-800℃, and / or the sintering treatment time is 60-120 min; and / or the acidic solution is a monobasic acid solution, and the mass fraction of the monobasic acid solution is 10-35%; preferably, the monobasic acid is hydrochloric acid and / or nitric acid; and / or the alkaline solution comprises a monobasic alkali and water, and the mass ratio of the residue, the monobasic alkali and the water is 1.5-100:40-60:50-400; and / or the monobasic alkali is NaOH and / or KOH; preferably, the waste molecular sieve is selected from any 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; and the sodium salt is Na2SO4 and / or NaCO3.

[0017] According to another aspect of the present application, there is provided a VOCs adsorbent prepared by the aforementioned preparation method.

[0018] By applying the technical solutions of the present application, the steps S3 and S4 of the present application optimize the structure of the 13X molecular sieve, forming a core-shell structure 13X molecular sieve with the 13X molecular sieve as the core, the nickel nanoparticles as the intermediate layer, and the titanium-silicon molecular sieve as the shell. In this process, the 13X molecular sieve is sequentially subjected to first impregnation treatment and second impregnation treatment, which can form a nickel nanoparticle intermediate layer and a titanium-silicon molecular sieve shell on the surface of the 13X molecular sieve in sequence, forming a gradient structure, which helps to improve the mechanical strength and thermal stability of the molecular sieve. And in this process, the structure of the 13X molecular sieve is greatly optimized, so that the obtained core-shell structure 13X molecular sieve has a certain range of specific surface area and porosity parameters. The above-mentioned core-shell structure 13X molecular sieve is subjected to ion exchange through step S5, and the introduced cerium ions not only effectively increase the specific surface area and pore volume of the molecular sieve, significantly improve the adsorption capacity of the molecular sieve for VOCs, but also promote the formation of more active sites. The VOCs adsorbent obtained by sequentially subjecting the calcined 13X molecular sieve to silanization modification treatment and second calcination treatment in step S6 further enhances the adsorption performance of the VOCs adsorbent. In addition, the 13X molecular sieve prepared by using waste catalyst as raw material in the present application not only realizes waste utilization and reduces the cost of preparation of 13X molecular sieve, but also the VOCs adsorbent prepared by the method of the present application has excellent physicochemical 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 technical solution for VOCs pollution problems. DETAILED DESCRIPTION

[0019] 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.

[0020] As analyzed in the background art of the present application, there is a problem of poor adsorption performance and low adsorption capacity of the VOCs adsorbent in the prior art. In order to solve this problem, the present application provides a VOCs adsorbent and a preparation method thereof.

[0021] In an exemplary embodiment of the present application, a preparation method of a VOCs adsorbent is provided, which comprises the following steps: step S1, sequentially subjecting waste molecular sieve to aluminum dissolution treatment and silicon dissolution treatment to obtain an aluminum-rich liquid and a silicon-rich liquid; step S2, sequentially subjecting raw materials comprising the aluminum-rich liquid, the silicon-rich liquid and seed crystals to gelation treatment, aging treatment and first hydrothermal crystallization treatment to obtain 13X molecular sieve; step S3, sequentially subjecting the 13X molecular sieve to first impregnation treatment and second impregnation treatment in a silanization reagent solution and a nickel-containing solution to obtain nickel-modified 13X molecular sieve; step S4, sequentially subjecting a mixture comprising the nickel-modified 13X molecular sieve and a titanium silicalite precursor solution to first hydrothermal reaction and calcination treatment to obtain core-shell structure 13X molecular sieve; step S5, sequentially subjecting cerium ion solution and the core-shell structure 13X molecular sieve to ion exchange reaction, drying, alkali solution treatment and first calcination treatment to obtain calcined 13X molecular sieve; and step S6, sequentially subjecting the calcined 13X molecular sieve to silanization modification treatment and second calcination treatment to obtain the VOCs adsorbent.

[0022] In steps S3 and S4 of the present application, the structure of the 13X molecular sieve is optimized to form core-shell structure 13X molecular sieve with the 13X molecular sieve as the core, nickel nanoparticles as the intermediate layer and titanium silicalite as the outer shell. In this process, the 13X molecular sieve is sequentially subjected to first impregnation treatment and second impregnation treatment, which can form nickel nanoparticle intermediate layer and titanium silicalite outer shell on the surface of the 13X molecular sieve in sequence to form a gradient structure, which helps to improve the mechanical strength and thermal stability of the molecular sieve. Moreover, in this process, the structure of the 13X molecular sieve is greatly optimized, so that the obtained core-shell structure 13X molecular sieve has a certain range of specific surface area and porosity parameters. The above-mentioned core-shell structure 13X molecular sieve is subjected to ion exchange in step S5, and the introduced cerium ions not only effectively increase the specific surface area and pore volume of the molecular sieve, significantly improve the adsorption capacity of the molecular sieve for VOCs, but also promote the formation of more active sites. The VOCs adsorbent obtained by sequentially subjecting the calcined 13X molecular sieve to silanization modification treatment and second calcination treatment in step S6 further enhances the adsorption performance of the VOCs adsorbent. In addition, the 13X molecular sieve prepared by using waste catalyst as raw material in the present application not only realizes waste utilization and reduces the cost of preparation of 13X molecular sieve, but also the VOCs adsorbent prepared by the method of the present application has excellent physicochemical 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 technical solution for VOCs pollution problems.

[0023] In an embodiment of the present application, in the step S3, the first impregnation treatment is performed for 8-24 hours; and / or the second impregnation treatment is performed for 24-48 hours; preferably, the molar concentration of the silane reagent solution is 0.05-0.2 mol / L; and / or the molar concentration of the nickel-containing solution is 0.05-0.2 mol / L; preferably, the mass of the 13X molecular sieve to the volume of the silane reagent solution is 400-600:1 g / L; preferably, the nickel-containing solution is a nickel nitrate solution and / or a nickel sulfate solution; preferably, the silane reagent is selected from any one or more of 3-aminopropyltriethoxysilane, tetraethoxysilane and tetramethoxysilane;

[0024] Preferably, the time of the first impregnation treatment, the time of the second impregnation treatment, the molar concentration of the silane reagent solution and the molar concentration of the nickel-containing solution are controlled within the above ranges, which helps to control the quality of the nickel nanoparticles formed finally and improve the impregnation effect of the silane reagent solution and the nickel-containing solution on the 13X molecular sieve; preferably, the type of the nickel-containing solution and the silane reagent are controlled within the above ranges, which helps to enrich the selectivity of the nickel-containing solution and the silane reagent solution.

[0025] In an embodiment of the present application, the step S3 further comprises: performing a third calcination on the 13X molecular sieve obtained after the second impregnation treatment to obtain a nickel-modified 13X molecular sieve coated with a layer of nickel nanoparticles; preferably, the third calcination is performed in a hydrogen atmosphere at a temperature of 500-600°C for 2-4 hours.

[0026] In the third calcination, the nickel compound attached to the surface of the 13X molecular sieve is decomposed at high temperature to form nickel oxide, and the hydrogen reduces the nickel oxide to nickel nanoparticles; preferably, controlling the temperature and the time of the third calcination within the above ranges helps to improve the efficiency of forming the nickel nanoparticles.

[0027] In an embodiment of the present application, in the step S4, the temperature of the first hydrothermal reaction is 150-200°C, and the time of the first hydrothermal reaction is 12-24h; preferably, the temperature of the calcination treatment is 450-550°C, and the time of the calcination treatment is 4-8h; the titanium-silicon molecular sieve precursor solution comprises a first silicon source, a titanium source, a template agent, a fluorine complex and water, wherein the first silicon source, the titanium source, the template agent, the fluorine complex and the water are mixed according to a molar ratio of 1:0.04-0.1:0.1-0.3:0.03-0.06:20-50; preferably, the mass of the nickel-modified 13X molecular sieve to the volume of the titanium-silicon molecular sieve precursor solution is 400-600:1g / L; preferably, the first silicon source is selected from any one or more of SiO2, Na2SiO3 and Si(OC2H5)4; preferably, the titanium source is selected from any one or more of TiO2, TiCl4 and Na2TiO3; preferably, the fluorine complex is selected from any one or more of sodium hexafluorophosphate, sodium hexafluoroacetyl acetonate and ammonium fluoride; and preferably, the template agent is an organic amine and / or a quaternary ammonium salt.

[0028] Preferably, the temperature and the time of the first hydrothermal reaction are controlled within the above ranges, which helps to improve the interaction between the titanium-silicon molecular sieve precursor and the nickel-modified 13X molecular sieve; preferably, the temperature and the time of the calcination treatment are controlled within the above ranges, which helps to improve the structural integrity of the finally formed core-shell structure 13X molecular sieve; preferably, the molar ratio of the first silicon source, the titanium source, the template agent, the fluorine complex and the water is controlled within the above ranges, which helps to improve the uniformity of the pore size of the core-shell structure 13X molecular sieve; and preferably, the types of the silicon source, the titanium source, the template agent and the fluorine complex are controlled within the above ranges, which helps to improve the synergistic effect among the components, so that the coating layer formed on the surface of the 13X molecular sieve has higher stability.

[0029] In an embodiment of the present application, in the step S5, the molar concentration of the cerium ion solution is 0.05-0.5mol / L in terms of cerium ions in the cerium ion solution, and preferably, the mass to volume ratio of the core-shell structure 13X molecular sieve to the cerium ion solution is 1-20:100g / mL; preferably, the cerium ion solution is selected from any one or more of cerium chloride, cerium nitrate, cerium citrate and cerium acetate; and / or the temperature of the ion exchange reaction is 45-60°C, and / or the time of the ion exchange reaction is 16-24h; preferably, the process of the alkali solution treatment comprises: performing a third impregnation treatment on the dried molecular sieve in an alkali solution, and preferably, the time of the third impregnation treatment is 1-3h; preferably, the alkali solution is NaOH and / or KOH; and preferably, the first calcination treatment is performed in an air atmosphere, and preferably, the temperature of the first calcination treatment is 400-600°C, and preferably, the time of the first calcination treatment is 5-8h.

[0030] Preferably, the molar concentration of the cerium ion solution, the mass of the core-shell structure 13X molecular sieve and the volume ratio of the cerium ion solution are controlled within the above ranges, which helps to control the amount of cerium ions introduced into the core-shell structure 13X molecular sieve, thereby controlling the modification degree of the core-shell structure 13X molecular sieve and the amount of active sites of the core-shell structure 13X molecular sieve. Preferably, the temperature and time of the ion exchange reaction are within the above ranges, which can promote the rate of the ion exchange reaction. Preferably, the type of the alkali solution and the time of the third impregnation in the alkali solution are within the above ranges, which helps to introduce mesopores and shorten the diffusion distance of the molecules in the pores. Preferably, the temperature and time of the first calcination treatment in air are within the above ranges, which can improve the efficiency and effect of the first calcination treatment, thereby improving the adsorption performance and adsorption capacity of the VOCs adsorbent.

[0031] In an embodiment of the present application, the time of the silanization modification treatment in the step S6 is 8-24 h; preferably, the volume ratio of the silane reagent to the solvent is 1:5-10; preferably, the reagents used in the silanization modification treatment include the silane reagent and the solvent; preferably, the silane reagent is selected from any one or more of methyltrimethoxysilane, ethyltriethoxysilane and propenyltrimethoxysilane; preferably, the solvent is selected from any one or more of ethanol, propanol and butanol; and / or the temperature of the second calcination treatment is 500-700°C, and the time of the second calcination treatment is 2-4 h.

[0032] The silanization modification treatment within the above ranges of the silane reagent and the solvent can improve the hydrophobicity of the titanium-silicon surface, thereby improving the adsorption performance and catalytic activity of the adsorbent. Preferably, the temperature and time of the second calcination treatment are within the above ranges, which can improve the efficiency and effect of the second calcination treatment.

[0033] In an embodiment of the present application, the 13X molecular sieve contains silicon elements and aluminum elements in the step S2, and the molar ratio of the silicon elements to the aluminum elements is 2.2-2.9:1; and / or the pore volume of the 13X molecular sieve is 0.3-0.5 cm 3 / g, and / or the specific surface area of the 13X molecular sieve is 700-950 m 2 / g.

[0034] Preferably, the steps S1 and S2 of the present application are used to prepare the 13X molecular sieve with the above properties. Within the above ranges, the molar ratio of the silicon elements to the aluminum elements helps to improve the utilization rate of the silicon source in the 13X molecular sieve; and the pore volume and the specific surface area of the 13X molecular sieve within the above ranges help to provide more adsorption sites and improve the flow and diffusion performance of VOCs inside the molecular sieve.

[0035] In an embodiment of the present application, the seed crystal contains SiO2, Al2O3, Na2O and H2O, wherein the molar ratio of SiO2 to Al2O3 is 0.01-2.5:1, and the molar ratio of Na2O, H2O to SiO2 is 0.01-4.0:1.0-40.0:1; and / or the molar ratio of SiO2 to Al2O3 is 4.6-5.0:1, and the molar ratio of Na2O, H2O to SiO2 is 1.8-2.0:40-50:1.

[0036] The above provides two different structures of seed crystals, preferably respectively controlling the molar ratio of SiO2 to Al2O3 and the molar ratio of Na2O, H2O to SiO2 within the above two ranges, providing a selection of diversified crystal nuclei for the formation of 13X molecular sieve, thereby helping to improve the formation and stability of the framework structure of 13X molecular sieve.

[0037] In an embodiment of the present application, the step S2 comprises: step S21, subjecting the aluminum-rich liquid and the silicon-rich liquid to gelation treatment to obtain a first gel; step S22, sequentially subjecting the first gel and the seed crystal to aging treatment and first hydrothermal crystallization treatment to obtain the 13X molecular sieve; wherein the first gel contains SiO2, Al2O3, Na2O and H2O, wherein the molar ratio of SiO2 to Al2O3 is 0.5-6.0:1, and the molar ratio of Na2O, H2O to SiO2 is 0.5-6.0:10-100:1; preferably the mass ratio of the seed crystal to the first gel is 5-20:100; and / or the temperature of the aging treatment is 20-100℃, and the time of the aging treatment is 0.1-24h; and / or the temperature of the first hydrothermal crystallization treatment is 60-105℃, and the time of the first hydrothermal crystallization treatment is 0.1-36h.

[0038] In addition, it is preferred that the aging process is carried out under stirring.

[0039] In order to promote the formation of 13X molecular sieve crystals, in an embodiment of the present application, the above preparation method further comprises a preparation process of the seed crystal, which comprises: stirring and mixing raw materials comprising an aluminum source, a second silicon source and water to obtain a second gel; adjusting the pH value of the second gel to 8.5-12.5 and then subjecting to second hydrothermal crystallization treatment to obtain the seed crystal; wherein the stirring and mixing rate is 200-800rpm, and / or the stirring and mixing temperature is 20-100℃, and / or the stirring and mixing time is 0.1-24h; preferably the pH value of the second gel is 11.8-12.2; further preferably the pH value of the above second gel is 12; preferably the second silicon source is selected from any one or more of silica sol, tetraethyl orthosilicate, coarse-pore silica gel, silicon powder, fly ash and white carbon black; preferably the aluminum source is selected from any one or more of sodium aluminate, pseudo-boehmite, aluminum sulfate and aluminum nitrate.

[0040] In order to improve the crystallization degree of the 13X molecular sieve, preferably, the second hydrothermal crystallization treatment comprises a first-stage hydrothermal crystallization treatment and a second-stage hydrothermal crystallization treatment, wherein the temperature of the first-stage hydrothermal crystallization treatment is 20-60℃, and / or the time of the first-stage hydrothermal crystallization treatment is 4-24h; preferably, the temperature of the second-stage hydrothermal crystallization treatment is 80-120℃, and / or the time of the second-stage hydrothermal crystallization treatment is 6-48h; further preferably, the temperature of the first-stage hydrothermal crystallization treatment is 35-45℃, and / or the time of the first-stage hydrothermal crystallization treatment is 11-13h; the temperature of the second-stage hydrothermal crystallization treatment is 90-100℃, and / or the time of the second-stage hydrothermal crystallization treatment is 22-26h; the temperature of the second-stage hydrothermal crystallization treatment is 50-60℃ higher than the temperature of the first-stage hydrothermal crystallization treatment; further preferably, the temperature of the first-stage hydrothermal crystallization treatment is 40℃, and / or the time of the first-stage hydrothermal crystallization treatment is 12h; the temperature of the second-stage hydrothermal crystallization treatment is 95℃, and / or the time of the second-stage hydrothermal crystallization treatment is 24h.

[0041] In addition, in order to further improve the mixing effect of the aluminum source, the silicon source and water, preferably, the specific steps of stirring and mixing the above-mentioned aluminum source, the second silicon source and water comprise: stirring and mixing the silicon source and water, the temperature of stirring and mixing is 20-60℃, the time of stirring and mixing is 0.1-12h, the rotating speed of stirring and mixing is 200-800rpm, to obtain a silicon-containing solution, the concentration of the silicon-containing solution is 28-99wt%; stirring and mixing the aluminum source and water, the temperature of stirring and mixing is 20-60℃, the time of stirring and mixing is 0.1-12h, the rotating speed of stirring and mixing is 200-800rpm, to obtain an aluminum-containing solution, the concentration of the aluminum-containing solution is 28-99wt%, and stirring and mixing the silicon-containing solution and the aluminum-containing solution to obtain the second gel.

[0042] Preferably, the way of adjusting the pH value of the second gel is to slowly add solid alkali or aqueous alkali solution into the second gel; preferably, the alkali is selected from sodium hydroxide and / or potassium hydroxide.

[0043] Preferably, after the first hydrothermal crystallization treatment in the step S22, the reaction product needs to be filtered and washed to neutral, and then dried at 80-120℃ to obtain the 13X molecular sieve without obvious weight loss.

[0044] In order to remove impurities such as water and carbon deposition in the waste molecular sieve, and further reduce the preparation cost of the 13X molecular sieve and increase the pore volume and specific surface area of the 13X molecular sieve, in an embodiment of the present application, the preparation method preferably further comprises a pretreatment process of the waste molecular sieve, and the pretreatment process comprises: sintering a mixture comprising the waste molecular sieve and a sodium salt to obtain a sintered product; sequentially performing aluminum dissolution treatment and solid-liquid separation on the sintered product by using an acidic solution to obtain an aluminum-rich liquid and a residue; sequentially performing silicon dissolution treatment and solid-liquid separation on the residue by using an alkaline solution to obtain a silicon-rich liquid; wherein the mass ratio of the waste molecular sieve to the sodium salt is 1:0.5-5; and / or the sintering temperature is 550-800°C, and / or the sintering time is 60-120 min; and / or the acidic solution is a monobasic acid solution, and the mass fraction of the monobasic acid solution is 10-35%; preferably the monobasic acid is hydrochloric acid and / or nitric acid; and / or the alkaline solution comprises a monobasic alkali and water, and the mass ratio of the residue, the monobasic alkali and the water is 1.5-100:40-60:50-400; and / or the monobasic alkali is NaOH and / or KOH; preferably the waste molecular sieve is selected from any 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; and the sodium salt is Na2SO4 and / or NaCO3.

[0045] In addition, preferably the size of the waste molecular sieve is less than 200 mesh; and preferably the sodium salt is NaCO3.

[0046] In another typical embodiment of the present application, a VOCs adsorbent is provided, which is prepared by the aforementioned preparation method.

[0047] The VOCs adsorbent prepared by the preparation method of the present application has high selectivity, high adsorption capacity, high diffusion performance and easy regeneration performance, and is suitable for environmental protection applications in many fields, especially industrial emissions and indoor air purification, and provides an efficient and environmentally friendly technical solution for VOC pollution problems.

[0048] The beneficial effects of the present application will be further illustrated in the following examples.

[0049] Example 1

[0050] 13X molecular sieve seed preparation: 21.0 g of silica sol (mass fraction 30%) was dissolved in 36.0 g of deionized water, and a silicon-containing solution was obtained after pretreatment at 25°C in a closed reaction kettle for 1 h; 24 g of aluminum sulfate was dissolved in 18.0 g of deionized water, and an aluminum-containing solution was obtained after stirring at 25°C for 1 h; the aluminum-containing solution was slowly added to the silicon-containing solution, and the solution after the addition was stirred at 60°C for 8 h to obtain a gel mixture; 6.74 g of sodium hydroxide was dissolved in 36 g of deionized water to obtain a sodium hydroxide aqueous solution, and the sodium hydroxide aqueous solution was added to the gel mixture to maintain the pH value of the gel mixture at 12 to obtain a second gel; the second gel was placed in a hydrothermal reaction kettle and subjected to two-stage hydrothermal crystallization treatment, the first-stage hydrothermal crystallization treatment was carried out at 40°C for 12 h, and the second-stage hydrothermal crystallization treatment was carried out at 95°C for 24 h to obtain a 13X molecular sieve seed solution; the 13X molecular sieve seed solution was sequentially subjected to filtration, washing, and drying to obtain 13X molecular sieve seeds. The molar ratio of SiO2 to Al2O3 in the 13X molecular sieve seeds was 1.5:1, and the molar ratio of Na2O, H2O to SiO2 was 1.6:32:1.

[0051] 13X molecular sieve preparation: waste Z-5 molecular sieve catalyst and NaCO3 were mixed at a mass ratio of 1:2.5 for sintering treatment, the sintering treatment was carried out at a temperature of 600°C for 100 min, then the sintered product was subjected to aluminum dissolution treatment with 25% hydrochloric acid, and then filtration was performed to obtain an aluminum-rich liquid and a residue; the residue was mixed with NaOH and H2O at a mass ratio of 50:50:200 for silicon dissolution treatment, and then filtration was performed to obtain a silicon-rich liquid; the silicon-rich liquid and the aluminum-rich liquid were mixed to obtain a first gel; the 13X molecular sieve seeds and the first gel were mixed at a mass ratio of 10:100, and then aging treatment and hydrothermal crystallization treatment were sequentially performed, the aging treatment was carried out at a temperature of 50°C for 12 h; the hydrothermal crystallization treatment was carried out at a temperature of 70°C for 24 h, and then drying was performed to obtain 13X molecular sieve. The molar ratio of SiO2 to Al2O3 in the first gel was 3.5:1, the molar ratio of Na2O, H2O to SiO2 was 2.8:80:1, the molar ratio of silicon to aluminum in the 13X molecular sieve was 2.60:1; the pore volume of the 13X molecular sieve was 0.4789 cm 3 / g, and the specific surface area of the 13X molecular sieve was 877.2 m 2 / g.

[0052] Preparation of the core-shell structured 13X molecular sieve: 300 g of the 13X molecular sieve powder was put into 500 mL of a 0.2 mol / L solution of 3-aminopropyltriethoxysilane for a first impregnation treatment, and the first impregnation treatment was performed for 8 hours; then the treated 3X molecular sieve was put into 500 mL of a 0.2 mol / L nickel nitrate solution for a second impregnation treatment, and the second impregnation treatment was performed for 24 hours; then the 13X molecular sieve after the second impregnation treatment was calcined at 500°C in a hydrogen atmosphere for a third calcination, and the third calcination was performed for 2 hours to obtain a nickel-modified 13X molecular sieve containing a nickel nanoparticle deposition layer. SiO2, TiO2, tetraethylammonium hydroxide, sodium hexafluorophosphate and water were mixed to prepare a titanium-silicon molecular sieve precursor solution, wherein the molar ratio of SiO2, TiO2, tetraethylammonium hydroxide, sodium hexafluorophosphate and water was 1:0.06:0.15:0.04:40; 150 g of the 13X molecular sieve containing the nickel nanoparticle deposition layer was added to 250 mL of the titanium-silicon molecular sieve precursor solution, and after being mixed thoroughly, it was transferred to a reaction kettle for a first hydrothermal reaction, and the first hydrothermal reaction was performed at a temperature of 150°C for 12 hours; after the reaction was completed, the solid was taken out and washed with water, and then dried at 110°C for 12 hours; the dried solid was subjected to a calcination treatment, and the calcination treatment was performed at a temperature of 450°C for 4 hours to obtain the core-shell structured 13X molecular sieve.

[0053] Preparation of the VOCs adsorbent: 50 g of the core-shell structured 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°C for 12 hours. The dried molecular sieve was soaked in a 2 mol / L sodium hydroxide (NaOH) solution for 2 hours, and then calcined at 500°C for 6 hours in air. Subsequently, the calcined molecular sieve was soaked in a mixed solution containing 50 mL of ethyl triethoxysilane (TEOS) and 450 mL of ethanol for 12 hours, and then dried and calcined at 600°C for 3 hours to form the VOCs adsorbent.

[0054] Example 2

[0055] The difference from Example 1 is that the preparation of 13X molecular sieve seeds: 1 g of silicon powder is dissolved in 18.0 g of deionized water, and after 1 hour of pretreatment at 25°C in a closed reaction kettle, a silicon-containing solution is obtained; 12 g of aluminum sulfate is dissolved in 18.0 g of deionized water, and after 1 h of stirring at 35°C, an aluminum-containing solution is obtained; the aluminum-containing solution is slowly added to the silicon-containing solution, and the solution after the addition is stirred at 50°C for 6 h to obtain a gel mixture; 2 g of sodium hydroxide is dissolved in 36 g of deionized water to obtain a sodium hydroxide aqueous solution, and the sodium hydroxide aqueous solution is added to the gel mixture, and the pH value of the gel mixture is controlled to maintain 11.8 to obtain a second gel; the second gel is placed in a hydrothermal reaction kettle, and two-stage hydrothermal crystallization treatment is carried out; the first-stage hydrothermal crystallization treatment is carried out at a temperature of 50°C for 14 hours, and the second-stage hydrothermal crystallization treatment is carried out at a temperature of 100°C for 18 hours to obtain a 13X molecular sieve seed solution; the 13X molecular sieve seed solution is sequentially filtered, washed, and dried to obtain 13X molecular sieve seeds, and finally a VOCs adsorbent is obtained. The molar ratio of SiO2 to Al2O3 of the 13X molecular sieve seeds is 0.6:1, the molar ratio of Na2O, H2O to SiO2 is 3:20:1, the silicon-aluminum ratio of the 13X molecular sieve is 2.40:1; the pore volume of the 13X molecular sieve is 0.4590 cm 3 / g, and the specific surface area of the 13X molecular sieve is 873.2 m 2 / g.

[0056] Example 3

[0057] The difference from Example 1 is that the preparation of 13X molecular sieve seeds: 0.17 g of silicon powder is dissolved in 6 g of deionized water, and after 1 hour of pretreatment at 25°C in a closed reaction kettle, a silicon-containing solution is obtained; 12 g of aluminum sulfate is dissolved in 18 g of deionized water, and after 1 h of stirring at 35°C, an aluminum-containing solution is obtained; the aluminum-containing solution is slowly added to the silicon-containing solution, and the solution after the completion of the dropwise addition is stirred at 100°C for 24 h to obtain a gel mixture; 0.9 g of sodium hydroxide is dissolved in 6 g of deionized water to obtain a sodium hydroxide aqueous solution, and the sodium hydroxide aqueous solution is added to the gel mixture, and the pH value of the gel mixture is controlled to maintain at 12.5, to obtain a second gel, and the second gel is placed in a hydrothermal reaction kettle for two-stage hydrothermal crystallization treatment, the first-stage hydrothermal crystallization treatment is carried out at a temperature of 60°C for 24 hours, and the second-stage hydrothermal crystallization treatment is carried out at a temperature of 120°C for 48 hours, to obtain a 13X molecular sieve seed solution, which is sequentially filtered, washed, and dried to obtain 13X molecular sieve seeds, and finally a VOCs adsorbent is obtained. The molar ratio of SiO2 to Al2O3 of the 13X molecular sieve seeds is 0.1:1, the molar ratio of Na2O, H2O to SiO2 is 4:1:1, the silicon-aluminum ratio of the 13X molecular sieve is 2.23:1; the pore volume of the 13X molecular sieve is 0.3693 cm 3 / g, and the specific surface area of the 13X molecular sieve is 801.2 m 2 / g.

[0058] Example 4

[0059] The difference from example 1 is that the preparation of 13X molecular sieve seed crystal: 14.65g of tetraethyl orthosilicate is dissolved in 36.0g of deionized water, and a silicon-containing solution is obtained after pretreatment at 25℃ in a closed reaction kettle for 1h; 12g of aluminum sulfate is dissolved in 18.0g of deionized water, and an aluminum-containing solution is obtained by stirring at 35℃ for 1h; the aluminum-containing solution is slowly added to the silicon-containing solution, and the solution after the addition is stirred at 20℃ for 0.1h to obtain a gel mixture; 0.56g of sodium hydroxide is dissolved in 6g of deionized water to obtain a sodium hydroxide aqueous solution, and the sodium hydroxide aqueous solution is added to the gel mixture to control the pH value of the gel mixture to maintain at 8.5, to obtain a second gel; the second gel is placed in a hydrothermal reaction kettle, and two-stage hydrothermal crystallization treatment is carried out, the first-stage hydrothermal crystallization treatment is carried out at a temperature of 20℃ for 4h, and the second-stage hydrothermal crystallization treatment is carried out at a temperature of 80℃ for 6h to obtain a 13X molecular sieve seed crystal solution; the 13X molecular sieve seed crystal solution is filtered, washed and dried in sequence to obtain 13X molecular sieve seed crystal, and finally the VOCs adsorbent is obtained. The molar ratio of SiO2 to Al2O3 of the 13X molecular sieve seed crystal is 2.5:1, the molar ratio of Na2O, H2O to SiO2 is 0.01:40:1, and the silicon-aluminum ratio of the 13X molecular sieve is 2.87:1; the pore volume of the 13X molecular sieve is 0.3916cm 3 / g, and the specific surface area of the 13X molecular sieve is 821.1m 2 / g.

[0060] Example 5

[0061] The difference from example 1 is that the first impregnation treatment time is 24h, the second impregnation treatment time is 48h, the molar concentration of the silanization reagent solution is 0.05mol / L, and the molar concentration of the nickel-containing solution is 0.05mol / L, and finally the VOCs adsorbent is obtained.

[0062] Example 6

[0063] The difference from example 1 is that the first impregnation treatment time is 7h, the second impregnation treatment time is 20h, the molar concentration of the silanization reagent solution is 0.04mol / L, and the molar concentration of the nickel-containing solution is 0.04mol / L, and finally the VOCs adsorbent is obtained.

[0064] Example 7

[0065] The difference from example 1 is that the third calcination temperature is 600℃, the third calcination time is 4h, and finally the VOCs adsorbent is obtained.

[0066] Example 8

[0067] The difference from Example 1 is that the temperature of the third calcination is 400℃, and the time of the third calcination is 1h, and finally the VOCs adsorbent is obtained.

[0068] Example 9

[0069] The difference from Example 1 is that the temperature of the first hydrothermal reaction is 200℃, the time of the first hydrothermal reaction is 24h, the temperature of the calcination treatment is 550℃, and the time of the calcination treatment is 8h, and finally the VOCs adsorbent is obtained.

[0070] Example 10

[0071] The difference from Example 1 is that the temperature of the first hydrothermal reaction is 140℃, the time of the first hydrothermal reaction is 10h, the temperature of the calcination treatment is 400℃, and the time of the calcination treatment is 3h, and finally the VOCs adsorbent is obtained.

[0072] Example 11

[0073] The difference from Example 1 is that the molar ratio of SiO2, TiO2, tetraethylammonium hydroxide, sodium hexafluorophosphate and water is 1:0.04:0.1:0.03:20, and finally the VOCs adsorbent is obtained.

[0074] Example 12

[0075] The difference from Example 1 is that the molar ratio of SiO2, TiO2, tetraethylammonium hydroxide, sodium hexafluorophosphate and water is 1:0.1:0.3:0.06:50, and finally the VOCs adsorbent is obtained.

[0076] Example 13

[0077] The difference from Example 1 is that the molar ratio of SiO2, TiO2, tetraethylammonium hydroxide, sodium hexafluorophosphate and water is 1:0.2:0.4:0.07:60, and finally the VOCs adsorbent is obtained.

[0078] Example 14

[0079] The difference from Example 1 is that the preparation of the VOCs adsorbent: 50g of the core-shell structure 13X molecular sieve is soaked in 1000mL of 0.05mol / L cerium chloride solution for ion exchange reaction, and finally the VOCs adsorbent is obtained.

[0080] Example 15

[0081] The difference from Example 1 is that the preparation of the VOCs adsorbent: 10g of the core-shell structure 13X molecular sieve is soaked in 1000mL of 0.2mol / L cerium chloride solution for ion exchange reaction, and finally the VOCs adsorbent is obtained.

[0082] Example 16

[0083] The difference from Example 1 is that the preparation of the VOCs adsorbent: 10 g of the core-shell structure 13X molecular sieve is soaked in 1000 mL of 0.5 mol / L cerium chloride solution for ion exchange reaction, and finally the VOCs adsorbent is obtained.

[0084] Example 17

[0085] The difference from Example 1 is that the preparation of the VOCs adsorbent: 10 g of the core-shell structure 13X molecular sieve is soaked in 1000 mL of 0.02 mol / L cerium chloride solution for ion exchange reaction, and finally the VOCs adsorbent is obtained.

[0086] Example 18

[0087] The difference from Example 1 is that the preparation of the VOCs adsorbent: 10 g of the core-shell structure 13X molecular sieve is soaked in 1000 mL of 0.6 mol / L cerium chloride solution for ion exchange reaction, and finally the VOCs adsorbent is obtained.

[0088] Comparative Example 1

[0089] The difference from Example 1 is that the 13X molecular sieve in step S2 is directly used as the VOCs adsorbent.

[0090] Comparative Example 2

[0091] The difference from Example 1 is that the core-shell structure 13X molecular sieve in step S4 is directly used as the VOCs adsorbent.

[0092] Comparative Example 3

[0093] The difference from Example 1 is that the core-shell structure 13X molecular sieve in step S4 is directly used for the treatment in step S6 to obtain the VOCs adsorbent.

[0094] Test method

[0095] The 13X molecular sieves and VOCs adsorbents obtained in the above examples and comparative examples are subjected to structural characterization and adsorption performance test of the VOCs adsorbent, and the selectivity and adsorption efficiency of the VOCs adsorbent to VOCs are shown in Table 1.

[0096] The test method of the silicon-aluminum ratio, pore volume and specific surface area of the 13X molecular sieves in Examples 1 to 4 is as follows:

[0097] The silicon-aluminum ratio of the 13X molecular sieve is determined by X-ray fluorescence spectroscopy (XRF);

[0098] 13X molecular sieve pore volume: BET test method;

[0099] 13X molecular sieve specific surface area: BET test method;

[0100] Adsorption performance of VOCs adsorbent: fixed bed adsorption experiment: low carbon alkane alkene (ethane, ethylene and propylene, the volume ratio is 1:1:1) is used as the adsorption object, passed through the fixed bed containing the adsorbent, and the concentration change through the bed layer is monitored to determine the adsorption capacity of the adsorbed VOCs weight (mg) / adsorbent weight (g), unit: mg / g.

[0101] Table 1

[0102]

[0103] From the above description, it can be seen that the above-mentioned embodiments of the present application achieve the following technical effects:

[0104] The steps S3 and S4 of the present application optimize the structure of the 13X molecular sieve to form a core-shell structure 13X molecular sieve with 13X molecular sieve as the core, nickel nanoparticles as the intermediate layer and titanium-silicon molecular sieve as the shell. In this process, the 13X molecular sieve is sequentially subjected to first and second impregnation treatments, which can form a nickel nanoparticle intermediate layer and a titanium-silicon molecular sieve shell on the surface of the 13X molecular sieve in sequence, forming a gradient structure, which helps to improve the mechanical strength and thermal stability of the molecular sieve. And in this process, the structure of the 13X molecular sieve is greatly optimized, so that the obtained core-shell structure 13X molecular sieve has a certain range of specific surface area and porosity parameters. The above-mentioned core-shell structure 13X molecular sieve is subjected to ion exchange through step S5, and the introduced cerium ions not only effectively increase the specific surface area and pore volume of the molecular sieve, significantly improve the adsorption capacity of the molecular sieve for VOCs, but also promote the formation of more active sites. The silanization modification treatment and the second calcination treatment of the calcined 13X molecular sieve in step S6 further enhance the adsorption performance of the VOCs adsorbent. In addition, the 13X molecular sieve prepared from waste catalyst in the present application not only realizes waste utilization, but also reduces the cost of preparing 13X molecular sieve. On the other hand, the VOCs adsorbent prepared by the method of the present application 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 technical solution for VOCs pollution problems.

[0105] The above merely describes the preferred embodiments of the present application, and is not used to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle 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 preparation method comprises the following steps: Step S1, sequentially performing aluminum dissolution treatment and silicon dissolution treatment on waste molecular sieve to obtain an aluminum-rich liquid and a silicon-rich liquid; Step S2, the step S2 comprises: Step S21, performing gelation treatment on the aluminum-rich liquid and the silicon-rich liquid to obtain a first gel; Step S22, sequentially performing aging treatment and first hydrothermal crystallization treatment on the first gel and seeds to obtain 13X molecular sieve; The preparation process of the seeds comprises: stirring and mixing raw materials comprising an aluminum source, a second silicon source and water to obtain a second gel; adjusting the pH value of the second gel to 8.5-12.5 and then performing second hydrothermal crystallization treatment to obtain the seeds; Step S3, sequentially performing first impregnation treatment and second impregnation treatment on the 13X molecular sieve in a silanization reagent solution and a nickel-containing solution to obtain nickel-modified 13X molecular sieve; Step S4, sequentially performing first hydrothermal reaction and calcination treatment on a mixture comprising the nickel-modified 13X molecular sieve and a titanium-silicon molecular sieve precursor solution to obtain core-shell structure 13X molecular sieve; Step S5, sequentially performing drying, alkali solution treatment and first calcination treatment on the core-shell structure 13X molecular sieve after ion exchange reaction of cerium ion solution to obtain calcined 13X molecular sieve; and Step S6, sequentially performing silanization modification treatment and second calcination treatment on the calcined 13X molecular sieve to obtain a VOCs adsorbent.

2. The production method according to claim 1, characterized by, In the step S3, the first impregnation treatment is performed for 8-24 h; and / or the second impregnation treatment is performed for 24-48 h.

3. The preparation method according to claim 1, characterized in that, In the step S3, the molar concentration of the silanization reagent solution is 0.05-0.2 mol / L; and / or the molar concentration of the nickel-containing solution is 0.05-0.2 mol / L.

4. The production method according to claim 1, characterized by, In the step S3, the mass of the 13X molecular sieve to the volume of the silanization reagent solution is 400-600:1 g / L.

5. The preparation method according to claim 1, characterized in that, In the step S3, the nickel-containing solution is a nickel nitrate solution and / or a nickel sulfate solution.

6. The method of claim 1, wherein, In the step S3, the silanization reagent is selected from any one or more of 3-aminopropyltriethoxysilane, tetraethoxysilane and tetramethoxysilane.

7. The preparation method according to claim 1, characterized in that, The step S3 further comprises: performing third calcination on the 13X molecular sieve obtained after the second impregnation treatment to obtain the nickel-modified 13X molecular sieve coated with a layer of nickel nanoparticles.

8. The preparation method according to claim 7, characterized in that, The step S3 further comprises: the atmosphere of the third calcination is hydrogen, the temperature of the third calcination is 500-600 DEG C, and the time of the third calcination is 2-4 h.

9. The production method according to any one of claims 1 to 8, characterized by, In the step S4, the temperature of the first hydrothermal reaction is 150-200 DEG C, and the time of the first hydrothermal reaction is 12-24 h.

10. The production method according to any one of claims 1 to 8, characterized by, In the step S4, the temperature of the calcination treatment is 450-550 DEG C, and the time of the calcination treatment is 4-8 h; The titanium silicalite molecular sieve precursor solution comprises a first silicon source, a titanium source, a template agent, a fluoride complex and water, wherein the first silicon source, the titanium source, the template agent, the fluoride complex and the water are mixed in a molar ratio of 1:0.04-0.1:0.1-0.3:0.03-0.06:20-50.

11. The production method according to any one of claims 1 to 8, characterized by, In the step S4, the mass of the nickel-modified 13X molecular sieve and the volume of the titanium silicalite molecular sieve precursor solution are in a ratio of 400-600:1 g / L.

12. The method of claim 10, wherein, The first silicon source is selected from any one or more of SiO2, Na2SiO3 and Si(OC2H5)4.

13. The preparation method according to claim 10, characterized in that, The titanium source is selected from any one or more of TiO2, TiCl4 and Na2TiO3.

14. The method of claim 10, wherein, The fluoride complex is selected from any one or more of sodium hexafluorophosphate, sodium hexafluoroacetyl acetonate and ammonium fluoride.

15. The preparation method according to claim 10, characterized in that, The template agent is an organic amine.

16. The production method according to any one of claims 1 to 8, characterized by, In the step S5, the molar concentration of the cerium ion solution is 0.05-0.5 mol / L, calculated based on cerium ions in the cerium ion solution.

17. The production method according to any one of claims 1 to 8, characterized by, In the step S5, the mass of the core-shell structure 13X molecular sieve and the volume of the cerium ion solution are in a ratio of 1-20:100 g / mL.

18. The production method according to any one of claims 1 to 8, characterized by, In the step S5, the cerium source in the cerium ion solution is selected from any one or more of cerium chloride, cerium nitrate, cerium citrate and cerium acetate; and / or the temperature of the ion exchange reaction is 45-60°C, and / or the time of the ion exchange reaction is 16-24 h.

19. The production method according to any one of claims 1 to 8, characterized by, In the step S5, the process of the alkali solution treatment comprises: performing third impregnation treatment on the dried molecular sieve in an alkali solution.

20. The method of claim 19, wherein, In the process of the alkali solution treatment, the time of the third impregnation treatment is 1-3 h.

21. The method of claim 19, wherein, In the step S5, the alkali solution is a NaOH solution and / or a KOH solution.

22. The production method according to any one of claims 1 to 8, characterized by, In the step S5, the first calcination treatment is performed in an air atmosphere.

23. The production method according to any one of claims 1 to 8, characterized by, In the step S5, the temperature of the first calcination treatment is 400-600°C.

24. The production method according to any one of claims 1 to 8, characterized by, In the step S5, the time of the first calcination treatment is 5-8 h.

25. The method of claim 1, wherein, In the step S6, the time of the silanization modification treatment is 8-24 h.

26. The production method according to any one of claims 1 to 8, characterized by, In the step S6, the reagents used in the silanization modification treatment comprise a silane reagent and a solvent.

27. The method of claim 26, wherein, The volume ratio of the silane reagent and the solvent is 1:5-10.

28. The preparation method according to claim 26, characterized in that, The silane reagent is selected from any one or more of methyltrimethoxysilane, ethyltriethoxysilane and propenyltrimethoxysilane.

29. The preparation method according to claim 26, characterized in that, The solvent is selected from any one or more of ethanol, propanol and butanol; and / or the temperature of the second calcination treatment is 500-700°C, and the time of the second calcination treatment is 2-4 h.

30. The method of claim 1, wherein, The step S22, the 13X molecular sieve contains silicon element and aluminum element, the molar ratio of the silicon element and the aluminum element is 2.2-2.9:1; and / or the pore volume of the 13X molecular sieve is 0.3-0.5cm 3 / g, and / or the specific surface area of the 13X molecular sieve is 700-950m 2 / g.

31. The method of claim 1, wherein, In the step S22, The crystal seed comprises SiO2, Al2O3, Na2O and H2O, wherein the molar ratio of the SiO2 and the Al2O3 is 0.01-2.5:1, and the molar ratio of the Na2O, the H2O and the SiO2 is 0.01-4.0:1.0-40.0:

1.

32. The method of claim 31, wherein, In the step S22, The molar ratio of SiO2 to Al2O3 is 4.6-5.0:1, and the molar ratio of Na2O, H2O to SiO2 is 1.8-2.0:40-50:

1.

33. The method of claim 1, wherein, In the step S21, the first gel comprises SiO2, Al2O3, Na2O and H2O, The molar ratio of SiO2 to Al2O3 is 0.5-6.0:1, and the molar ratio of Na2O, H2O to SiO2 is 0.5-6.0:10-100:

1.

34. The production method according to any one of claims 1 to 8, characterized by, In the step S22, The mass ratio of the seed crystal to the first gel is 5-20:100; The temperature of the aging treatment is 20-100℃, the time of the aging treatment is 0.1-24h; and / or the temperature of the first hydrothermal crystallization treatment is 60-105℃, and the time of the first hydrothermal crystallization treatment is 0.1-36h.

35. The production method according to any one of claims 1 to 8, wherein In the preparation of the seed crystal, The stirring rate is 200-800rpm, and / or the stirring temperature is 20-100℃, and / or the stirring time is 0.1-24h.

36. The production method according to any one of claims 1 to 8, characterized by, In the preparation of the seed crystal, the pH value of the second gel is adjusted to 11.8-12.

2.

37. The method of claim 1, wherein, In the preparation of the seed crystal, the second silicon source is selected from any one or more of silica sol, tetraethyl orthosilicate, coarse-pore silica gel, silicon powder, fly ash, and white carbon black.

38. The method of claim 1, wherein, In the preparation of the seed crystal, the aluminum source is selected from any one or more of sodium aluminate, pseudo-boehmite, aluminum sulfate, and aluminum nitrate.

39. The method of claim 1, wherein, In the preparation of the seed crystal, The second hydrothermal crystallization treatment comprises a first-stage hydrothermal crystallization treatment and a second-stage hydrothermal crystallization treatment, wherein, The temperature of the first-stage hydrothermal crystallization treatment is 20-60℃, and / or the time of the first-stage hydrothermal crystallization treatment is 4-24h.

40. The preparation method according to claim 39, characterized in that, The temperature of the second-stage hydrothermal crystallization treatment is 80-120℃, and / or the time of the second-stage hydrothermal crystallization treatment is 6-48h.

41. The preparation method of claim 39, wherein, The temperature of the first-stage hydrothermal crystallization treatment is 35-45℃, and / or the time of the first-stage hydrothermal crystallization treatment is 11-13h; The temperature of the second-stage hydrothermal crystallization treatment is 90-100℃, and / or the time of the second-stage hydrothermal crystallization treatment is 22-26h; The temperature of the second-stage hydrothermal crystallization treatment is 50-60℃ higher than the temperature of the first-stage hydrothermal crystallization treatment.

42. A VOCs adsorbent, characterized in that, The VOCs adsorbent is prepared by the preparation method of any one of claims 1-40.

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