Modified titanium silicalite molecular sieve as well as preparation method and application thereof

Abstract

The invention discloses a modified titanium silicalite molecular sieve as well as a preparation method and application thereof. The modified titanium silicalite molecular sieve comprises an ETS-10 molecular sieve as well as lanthanum, barium and silver which are supported on the ETS-10 molecular sieve. In the modified titanium silicalite molecular sieve, the atomic ratio of silicon to titanium is 4.5-5.5, the mass percent of lanthanum is 0.1%-6.0%, the mass percent of barium is 0.1%-10.0%, and the mass percent of silver is 0.1%-15.0%. By doping lanthanum, the structural stability of the titanium silicalite molecular sieve is improved, and barium exchange modification occupies exchange sites of a seven-membered ring and a five-membered ring in the ETS-10 molecular sieve, so that the loading amount of silver is reduced; the modified titanium silicalite molecular sieve has high stability, low silver loading capacity and excellent xenon adsorption selectivity, is suitable for rapid trapping and separation of gaseous effluents of a nuclear power plant and xenon in ambient air, and has good application value.

Description

Technical Field

[0001] The invention relates to the technical field of molecular sieves, and in particular to a modified titanium silicon molecular sieve and a preparation method and application thereof. Background Art

[0002] The “dual carbon” goal has put forward new requirements for energy development. Nuclear power technology with zero carbon emission costs has once again become the focus of attention, and nuclear power will enter a period of rapid development. However, the operation of nuclear power will produce radioactive and hazardous substances, including 133 Xe (half-life 36.4 days) and 85 Kr (half-life is 10.7 years), etc. 133 Xe accounts for half of the total amount of radioactive noble gases. Trace amounts of xenon (Xe) isotopes are the most difficult radionuclides to control in nuclear power plants. They are easily released into the environment and continue to accumulate, posing a great threat to the ecological environment. The radioactive xenon emitted by nuclear power plants through gaseous effluents will be released into the environment through the chimneys of nuclear power plants. Since the ventilation volume of chimneys is extremely large and their chemical composition is similar to that of ambient air, the amount of radioactive xenon can be ignored compared to the amount of stable xenon. Therefore, the capture and separation of stable xenon in gaseous effluents is achieved, that is, the capture and separation of radioactive xenon is achieved. In the monitoring of radioactive xenon in gaseous effluents of nuclear power plants, through the application of new xenon adsorption and separation materials, the detection of radioactive xenon after rapid enrichment and separation of xenon by materials will greatly reduce its detection limit level, and it is expected to promote the realization of quasi-online monitoring of radioactive xenon in gaseous effluents of nuclear power plants. Therefore, the development of efficient capture and separation materials suitable for xenon in gaseous effluents is of great significance for promoting the online monitoring of xenon in gaseous effluents of nuclear power plants.

[0003] However, the content of xenon in gaseous effluents and ambient air is extremely low, with a concentration of 0.087ppmv, and separation and enrichment are very difficult. In the field of air separation, commonly used xenon enrichment and separation methods include cryogenic distillation, membrane separation technology, solvent absorption method, adsorption separation, etc. Among them, cryogenic distillation has the disadvantages of high energy consumption ratio and high cost, solvent absorption method has the problem of secondary pollution caused by solvent leakage, and membrane separation method has the disadvantages of high cost and low efficiency; adsorption separation uses porous materials for selective adsorption of xenon enrichment, which has the advantages of low energy consumption and simple equipment, and is currently a more promising method. Zeolite molecular sieve is the most important industrial adsorption material, but most materials have low xenon selectivity and adsorption capacity, which makes it difficult to meet the needs of rapid capture and separation of radioactive xenon in gaseous effluents of nuclear power plants. Zeolite molecular sieves contain abundant ion exchange sites. The pore size and pore adsorption potential field of the molecular sieve can be changed by metal cation exchange, thereby realizing the modulation of the adsorption performance of the molecular sieve. Ag ions have a 3d empty orbital structure and are easy to form π complexes with xenon-krypton gases, showing unusual inert gas selective adsorption characteristics. The framework of ETS-10 titanium silicalite is composed of [SiO4] tetrahedrons and [TiO6] octahedrons connected by oxygen bridges, forming a three-dimensional pore structure containing 12-membered rings, 7-membered rings, and 5-membered rings. The Ti site can provide two silver ion exchange sites, making it a preferred material for xenon-krypton enrichment. However, the main problem with ETS-10 molecular sieves is that the structural stability is poor, and only the exchange sites of the 12-membered rings are effective adsorption sites. Therefore, improving the structural stability of modified titanium silicalite, increasing the effective silver loading and reducing costs are the main problems currently facing the modification and application of this material.

[0004] U.S. Patent US4853202A discloses a method for synthesizing ETS-10, using titanium trichloride as a titanium source. Titanium trichloride will not hydrolyze directly, and will only hydrolyze and generate precipitation when it is converted into tetravalent, which usually leads to poor stability of the resulting molecular sieve. Chinese patent CN201810986390.2 discloses a method for synthesizing ETS-10 without a template agent, which has a quartz impurity phase and results in a low crystallinity and a long reaction time. In many studies, organic templates such as quaternary ammonium salts and fatty ammonium are used to synthesize ETS-10 to improve the crystallinity and stability of titanium silicon molecular sieves, but this also greatly increases the cost of molecular sieve synthesis. For example, CCPavel et al. [Microporous Mesoporous Mater., 71, 77-85, 2004] prepared ETS-10 molecular sieves with good crystallinity by improving the template agent, but the synthesized molecular sieve still contains ETS-4 impurities. The document [Ind.Eng.Chem.Res., 58, 4560-4571, 2019] reports the latest progress of silver-modified ETS-10 molecular sieve, which has achieved good xenon adsorption performance. However, the material adopts the ETS-10 industrial preparation method disclosed in US4853202A, and the high-temperature stability is not improved, and the silver loading reaches more than 20wt%. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a modified titanium silicon molecular sieve and a preparation method and application thereof.

[0006] The technical solution adopted by the present invention to solve the technical problem is: providing a modified titanium silicon molecular sieve, including an ETS-10 molecular sieve as a carrier and La, Ba and Ag supported on the ETS-10 molecular sieve;

[0007] In the modified titanium silicon molecular sieve, the atomic ratio of silicon to titanium is 4.5-5.5, the mass percentage of La is 0.1%-6.0%, the mass percentage of Ba is 0.1%-10.0%, and the mass percentage of Ag is 0.1%-15.0%;

[0008] The specific surface area of ​​the modified titanium silicalite is 250 m 2 / g~500m 2 / g.

[0009] In some embodiments, the particle size of the modified titanium silicalite is 2 mm to 5 mm.

[0010] In some embodiments, in the modified titanium silicalite molecular sieve, the mass percentage of La is 1.0% to 4.0%, the mass percentage of Ba is 0.1% to 8.0%, and the mass percentage of Ag is 6.0% to 15.0%.

[0011] In some embodiments, the Ag in the modified titanium silicalite molecular sieve exists in the form of one or more of silver ions, silver atoms, silver nanoclusters, and silver nanoparticles for exchange.

[0012] In some embodiments, the specific surface area of ​​the modified titanium silicalite after calcination in air at 450°C for 2 hours is greater than 300 m 2 / g.

[0013] In some embodiments, the modified titanium silicalite has a xenon adsorption capacity greater than 5.0 ml / ml at 298K and 10 Pa.

[0014] The present invention also provides a method for preparing a modified titanium silicon molecular sieve, comprising the following steps:

[0015] S1. Synthesis of lanthanum-modified ETS-10 molecular sieve: mixing sulfuric acid solution with anatase titanium oxide and ball-milling to form a uniform titanium oxide slurry; mixing titanium oxide slurry, silicon source, sodium hydroxide, potassium hydroxide, lanthanum salt and potassium fluoride, stirring to form a uniform sol, placing the sol in a high-pressure reactor and reacting at 220° C. for 48 h to 72 h, filtering, washing and drying, and then calcining at 300° C. to 550° C. for 1 h to 4 h to obtain a lanthanum-modified ETS-10 molecular sieve;

[0016] S2, barium-modified ETS-10 molecular sieve: according to the weight ratio of barium nitrate solution to lanthanum-modified ETS-10 molecular sieve of 10 to 60, the lanthanum-modified ETS-10 molecular sieve is placed in 0.05 mol / L to 0.5 mol / L barium nitrate solution for exchange for 1h to 2h, and the exchange temperature is 30°C to 45°C; after filtering, washing and drying, the barium-modified ETS-10 molecular sieve is obtained;

[0017] S3. Silver loading: 0.001 mol / L to 0.5 mol / L silver salt solution is loaded onto the barium-modified ETS-10 molecular sieve by equal volume impregnation, and the silver loading amount is adjusted according to the predetermined silver loading amount by the concentration of the silver salt solution. After drying at 80°C to 120°C for 2 to 12 hours, a silver-loaded ETS-10 molecular sieve precursor is obtained; the silver-loaded ETS-10 molecular sieve precursor is calcined at 300°C to 550°C for 2 hours to 4 hours, and pressed into tablets to form a granular modified titanium silicalite molecular sieve.

[0018] In some embodiments, in step S1, the molar ratio of the substance in the sol is as follows:

[0019] SiO2:TiO2:Na2O:K2O:F - :La:H2O=4.5~6.5:1:2~8:0.5~3:0.2~1.0:0.01~0.18:120~180.

[0021] In some embodiments, the molar ratio of SiO2 to (Na2O+K2O) in the sol is 1-2, and the molar ratio of Na2O to K2O is 1.5-9.

[0022] In some embodiments, in step S1, the silicon source includes at least one of sodium silicate, silica sol, and fumed silica;

[0023] In some embodiments, in step S3, the silver salt is at least one of silver nitrate and silver acetate.

[0024] The present invention also provides an application of the modified titanium silicon molecular sieve for rapid capture and separation of xenon in gaseous effluents of nuclear power plants and ambient air.

[0025] The modified titanium silicalite molecular sieve of the present invention helps to improve the structural stability of the titanium silicalite molecular sieve through La doping, occupies the exchange sites of the seven-membered ring and the five-membered ring in the ETS-10 molecular sieve through Ba exchange modification, and thus reduces the silver loading; the modified titanium silicalite molecular sieve has high stability, low silver loading and excellent xenon adsorption selectivity, is suitable for the rapid capture and separation of xenon in gaseous effluents of nuclear power plants and ambient air, and has good application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0027] Figure 1 is the XRD diagram of the samples obtained in Examples 1 to 4 of the present invention;

[0028] Figure 2 It is a comparison chart of the specific surface areas of the samples obtained in Examples 1 to 4 of the present invention and the comparative example;

[0029] Figure 3 It is a comparison chart of the xenon adsorption amount of samples obtained from Examples 1 to 4 of the present invention and the comparative example. DETAILED DESCRIPTION

[0030] The modified titanium silicalite molecular sieve of the invention comprises an ETS-10 molecular sieve as a carrier and La, Ba and Ag supported on the ETS-10 molecular sieve.

[0031] The modified titanium silicalite molecular sieve is obtained by modifying titanium silicalite molecular sieve (ie, ETS-10 molecular sieve) with lanthanum, exchanging with barium and loading silver. In the modified titanium silicalite molecular sieve, the atomic ratio of silicon to titanium is 4.5-5.5.

[0032] The framework of titanium silicon molecular sieve can be expressed as ︱(Na,K)2+(H2O)4︱[TiSi5O 13], the theoretical atomic ratio of titanium to silicon is 1:5. Since hydrothermal synthesis will introduce many structural defects, the present invention selects a titanium silicon molecular sieve with an atomic ratio of silicon to titanium of 4.5 to 5.5, and preferably a titanium silicon molecular sieve with a silicon-titanium atomic ratio close to 5.

[0033] In the modified titanium silicon molecular sieve, the doping of La (lanthanum) helps to improve the structural stability of the titanium silicon molecular sieve. Under the condition of not affecting the crystal structure of the titanium silicon molecular sieve, the mass percentage of La in the modified titanium silicon molecular sieve is 0.1% to 6.0%, preferably 1.0% to 4.0%, and more preferably 2.0% to 3.0%.

[0034] In the modified titanium silicalite molecular sieve, the purpose of the exchange of barium (Ba) is to occupy the exchange sites of the seven-membered ring and the five-membered ring in the ETS-10 molecular sieve, thereby reducing the amount of silver supported. The mass percentage of Ba is 0.1% to 10.0%, preferably 0.1% to 8.0%, and further preferably 3.0% to 6.0%.

[0035] The mass percentage of Ag (silver) in the modified titanium silicate molecular sieve (i.e., the silver loading) is 0.1% to 15.0%, preferably 6.0% to 15.0%, and more preferably 10.0% to 15.0%. Thus, the silver loading in the modified titanium silicate molecular sieve is less than 15wt%.

[0036] The presence of Ag (silver) in the modified titanium silicalite molecular sieve includes one or more of silver ions, silver atoms, silver nanoclusters and silver nanoparticles for exchange. In some embodiments, the presence of Ag (silver) in the modified titanium silicalite molecular sieve includes silver ions and / or silver atoms.

[0037] In some embodiments, the modified titanium silicalite molecular sieve is in a granular form, and the particle size thereof may be 2 mm to 5 mm.

[0038] In some embodiments, the xenon adsorption of the modified titanium silicate at 298K and 10Pa is greater than 5.0ml / ml, and further greater than 6.0ml / ml. For the granular modified titanium silicate, the xenon adsorption at 298K and 10Pa is greater than 6.5ml / ml.

[0039] The specific surface area of ​​the modified titanium silicate molecular sieve is 250m 2 / g~500m 2 In some embodiments, the specific surface area of ​​the modified titanium silicon molecular sieve after being calcined in air at 450° C. for 2 hours is greater than 300 m 2 / g, further greater than 350m 2 / g.

[0040] The preparation method of the modified titanium silicate molecular sieve according to one embodiment of the present invention may include the following steps:

[0041] S1. Synthesis of lanthanum-modified ETS-10 molecular sieve. Specifically including:

[0042] S1.1, mix 1 mol / L sulfuric acid solution and anatase titanium oxide and ball mill for 0.5h to 4h to form a uniform titanium oxide slurry. In one embodiment, the titanium oxide content in the titanium oxide slurry is 25wt% to 50wt%.

[0043] Anatase titanium oxide is in the form of particles, and its diameter is less than 1 micrometer, preferably less than 0.5 micrometer, and more preferably less than 0.2 micrometer.

[0044] S1.2, titanium oxide slurry, silicon source, sodium hydroxide, potassium hydroxide, lanthanum salt and potassium fluoride are mixed and stirred to form a uniform sol. Distilled water may also be added thereto.

[0045] The molar ratios of substances in the sol are as follows:

[0046] SiO2:TiO2:Na2O:K2O:F - :La:H2O=4.5~6.5:1:2~8:0.5~3:0.2~1.0:0.01~0.18:120~180.

[0048] Preferably, the molar ratio of SiO2 to (Na2O+K2O) in the sol is 1 to 2, and the molar ratio of Na2O to K2O is 1.5 to 9. More preferably, the molar ratio of SiO2 to (Na2O+K2O) is 1.2 to 1.5, and the molar ratio of Na2O to K2O is 2 to 5.

[0049] The silicon source includes at least one of sodium silicate, silica sol, and fumed silica. The lanthanum salt includes at least one of lanthanum nitrate, lanthanum chloride, and lanthanum hydroxide.

[0050] S1.3. Place the sol in a high-pressure reactor and react at 220°C for 48h to 72h. After filtering, washing and drying, calcine at 300°C to 550°C for 1h to 4h to obtain lanthanum-modified ETS-10 molecular sieve.

[0051] S2, barium modified ETS-10 molecular sieve.

[0052] According to the weight ratio of barium nitrate solution to lanthanum modified ETS-10 molecular sieve of 10 to 60, the lanthanum modified ETS-10 molecular sieve is placed in 0.05 mol / L to 0.5 mol / L barium nitrate solution for exchange for 1h to 2h, and the exchange temperature is 30° C. to 45° C. After exchange, it is filtered, washed, and dried at 80° C. to 120° C. for 2h to 12h to obtain the barium modified ETS-10 molecular sieve.

[0053] The purpose of barium (Ba) exchange is to occupy the exchange sites of the seven-membered ring and the five-membered ring in the ETS-10 molecular sieve, thereby reducing the silver loading in the subsequent steps.

[0054] S3, silver loading: 0.001mol / L to 0.5mol / L silver salt solution is loaded onto the barium-modified ETS-10 molecular sieve by equal volume impregnation, and the silver loading amount is adjusted by the concentration of the silver salt solution according to the predetermined silver loading amount; after drying at 80℃ to 120℃ for 2 to 12 hours, the silver-loaded ETS-10 molecular sieve precursor is obtained; the silver-loaded ETS-10 molecular sieve precursor is calcined at 300℃ to 550℃ for 2 hours to 4 hours, and the granular modified titanium silicon molecular sieve is formed by tableting. The particle size of the granular modified titanium silicon molecular sieve can be 2mm to 5mm.

[0055] The silver salt solution is prepared by using silver salt, which is at least one of silver nitrate and silver acetate, preferably silver acetate.

[0056] The modified titanium silicalite of the present invention has a xenon adsorption capacity of greater than 5.0 ml / ml (can reach greater than 6.5 ml / ml) at 298K and 10Pa, has excellent xenon adsorption selectivity, and is suitable for rapid capture and separation of xenon in gaseous effluents of nuclear power plants and ambient air.

[0057] The present invention will be further described below with reference to specific embodiments.

[0058] Example 1

[0059] Step (1): Mix 40 mL of 1 mol / L sulfuric acid solution and 30 g of anatase titanium oxide and ball mill for 2 hours, add water to make a 40% titanium oxide slurry; take 3.3 g of anatase titanium oxide slurry, 20 g 40% sodium silicate solution (27% SiO2, 8% Na2O), 4.7g sodium hydroxide, 4.2g potassium hydroxide, 0.36g lanthanum nitrate hexahydrate, 32.0g distilled water and 0.76g potassium fluoride were stirred and mixed, and stirring was continued for 4 hours to form a uniform sol, and the molar ratio of the sol substances was SiO2:TiO2:Na2O:K2O:F-:La:H2O=5.5:1:4.4:2.2:0.8:0.05:160; the obtained sol was placed in a high-pressure reactor and reacted at 220°C for 48h; after filtering, washing, drying at 80°C for 8h, and calcining at 350°C for 1h, a lanthanum-modified ETS-10 molecular sieve was obtained.

[0060] Step (2): Take 10g of lanthanum-modified ETS-10 molecular sieve, add 200ml of 0.02mol / L barium nitrate solution, exchange at 40°C for 2 hours, filter and wash, and then dry at 110°C for 2 to 12 hours to obtain barium-lanthanum-modified ETS-10 molecular sieve.

[0061] Step (3): Take 10g of barium-lanthanum modified ETS-10 molecular sieve, load 15mL of 0.6mol / L silver nitrate solution onto the barium-modified ETS-10 molecular sieve by equal volume impregnation, adjust the silver loading amount by the concentration of the silver salt solution according to the predetermined silver loading amount, and obtain a silver-loaded ETS-10 molecular sieve precursor after drying at 110°C for 6h; calcine the silver-loaded ETS-10 molecular sieve precursor in a converter at 400°C for 2h, and then press into tablets to form 2.8mm granular Ag / Ba / La-modified ETS-10 molecular sieve, marked as sample 1.

[0062] The Ag content of the modified ETS-10 molecular sieve material obtained is 15.1wt%, the Ba content is 2.5wt%, and the La content is 1.0wt%. The XRD pattern of the crystal structure of the obtained material is as follows: Figure 1 As shown, the specific surface area of ​​the obtained material is Figure 2 As shown, the xenon adsorption capacity of the obtained material at 298K and 10Pa is as follows Figure 3 shown.

[0063] Example 2

[0064] Step (1): The preparation and addition amount of titanium oxide slurry are the same as those in Example 1. 20 g of sodium silicate (27% SiO2, 8% Na2O), 4.6 g of sodium hydroxide, 3.3 g of potassium hydroxide, 0.9 g of lanthanum nitrate hexahydrate, 34.0 g of distilled water and 0.76 g of potassium fluoride are stirred and mixed, and stirred for 6 hours to form a uniform sol, and the molar ratio of the sol substances is SiO2:TiO2:Na2O:K2O:F-:La:H2O=5.5:1:5:1.7:0.8:0.125:160; the obtained sol is placed in an autoclave and reacted at 220°C for 48 hours; after filtering, washing, drying at 80°C for 8 hours, and calcining at 350°C for 1 hour, a lanthanum-modified ETS-10 molecular sieve is obtained.

[0065] Step (2): The preparation of barium-lanthanum modified ETS-10 molecular sieve is the same as step (2) of Example 1, wherein the concentration of the barium nitrate solution is 0.12 mol / L.

[0066] Step (3): The silver loading process is the same as step (3) of Example 1, wherein the silver nitrate loading amount is 15 mL of 0.6 mol / L silver nitrate solution, and a modified ETS-10 molecular sieve is obtained, which is marked as sample 2.

[0067] The Ag content of the modified ETS-10 molecular sieve material obtained is 14.4wt%, the Ba content is 4.1wt%, and the La content is 2.6wt%. The XRD pattern of the crystal structure of the obtained material is shown in FIG. Figure 1 As shown, the specific surface area of ​​the obtained material is Figure 2 As shown, the xenon adsorption capacity of the obtained material at 298K and 10Pa is as follows Figure 3 shown.

[0068] Example 3

[0069] Step (1): Preparation of titanium oxide slurry and the amount of addition, sodium silicate and potassium fluoride are the same as in Example 1. 3.3 g of anatase titanium oxide slurry, 20 g of 40% sodium silicate solution (27% SiO2, 8% Na2O), 4.6 g of sodium hydroxide, 3.3 g of potassium hydroxide, 1.3 g of lanthanum nitrate hexahydrate, 32 g of distilled water and 0.76 g of potassium fluoride are stirred and mixed, and a uniform sol is formed after stirring for 4 hours. The molar ratio of the sol substances is SiO2:TiO2:Na2O:K2O:F-:La:H2O=5.5:1:5:1.7:0.8:0.18:160; the obtained sol is placed in an autoclave and reacted at 220°C for 48 hours; after filtering, washing, drying at 80°C for 8 hours, and calcining at 350°C for 1 hour, a lanthanum-modified ETS-10 molecular sieve is obtained.

[0070] Step (2): Take 10g La-ETS-10, add 200ml 0.12mol / L barium nitrate solution, exchange at 40°C for 2 hours, filter and wash, and then dry at 110°C for 2 to 12 hours to obtain barium lanthanum modified ETS-10 molecular sieve.

[0071] Step (3): Take 10g of barium-lanthanum modified ETS-10 molecular sieve, load 15mL of 0.55mol / L silver acetate solution onto the barium-modified ETS-10 molecular sieve by equal volume impregnation, adjust the silver loading amount by the concentration of the silver salt solution according to the predetermined silver loading amount, and obtain the silver-loaded ETS-10 molecular sieve precursor after drying at 110°C for 6h. The silver-loaded ETS-10 molecular sieve precursor is calcined in a converter at 350°C for 2h, and then pressed into tablets to form 2-5mm granular Ag / Ba / La-modified ETS-10 molecular sieves, marked as sample 3.

[0072] The Ag content of the modified ETS-10 molecular sieve material obtained is 12.3wt%, the Ba content is 4.1wt%, and the La content is 3.5wt%. The XRD pattern of the crystal structure of the obtained material is as follows: Figure 1 As shown, the specific surface area of ​​the obtained material is Figure 2 As shown, the xenon adsorption capacity of the obtained material at 298K and 10Pa is as follows Figure 3 shown.

[0073] Example 4

[0074] Step (1): Preparation of titanium oxide slurry and the amount of addition, sodium silicate and potassium fluoride are the same as in Example 1. 3.3 g of anatase titanium oxide slurry, 20 g of 40% sodium silicate solution (27% SiO2, 8% Na2O), 3.8 g of sodium hydroxide, 4.2 g of potassium hydroxide, 1.0 g of lanthanum nitrate hexahydrate, 34 g of distilled water and 0.76 g of potassium fluoride are stirred and mixed, and a uniform sol is formed after stirring for 4 hours. The molar ratio of the sol substances is SiO2:TiO2:Na2O:K2O:F-:La:H2O=5.5:1:4.4:2.2:0.8:0.15:160; the obtained sol is placed in an autoclave and reacted at 220°C for 48 hours; after filtering, washing, drying at 80°C for 8 hours, and calcining at 350°C for 1 hour, a lanthanum-modified ETS-10 molecular sieve is obtained.

[0075] Step (2): The preparation of barium-lanthanum modified ETS-10 molecular sieve is the same as step (2) of Example 1, wherein the concentration of the barium nitrate solution is 0.25 mol / L.

[0076] Step (3): The silver loading process is the same as step (3) of Example 1, wherein the silver nitrate loading amount is 15 mL of 0.4 mol / L silver nitrate solution, and a modified ETS-10 molecular sieve is obtained, which is marked as sample 4.

[0077] The Ag content of the modified ETS-10 molecular sieve material obtained is 9.7wt%, the Ba content is 6.1wt%, and the La content is 2.9wt%. The XRD pattern of the crystal structure of the obtained material is shown in Figure 1 As shown, the specific surface area of ​​the obtained material is Figure 2 As shown, the xenon adsorption capacity of the obtained material at 298K and 10Pa is as follows Figure 3 shown.

[0078] Comparative Example 1

[0079] 20g of sodium silicate (27% SiO2, 8% Na2O), 6.9g of sodium hydroxide, 1.3g of potassium hydroxide, 25g of distilled water and 20g of 15wt% titanium trichloride solution were mixed and stirred for 4 hours to form a sol, and then the obtained sol was placed in an autoclave and heated at 215°C for 48 hours. The material was then thoroughly washed with deionized water, dried in an oven at 80°C, and calcined at 350°C for 1h to obtain sodium-potassium ETS-10.

[0080] Take 10g of sodium potassium ETS-10, add 150ml of 0.5mol / L ammonium chloride solution, exchange at 80℃ for 2 hours, repeat twice to obtain ammonia ETS-10. Take 10g of ammonium ETS-10 powder, add 150ml of 0.1mol / L silver nitrate solution, exchange in a 40℃ water bath for 2 hours and repeat twice, then calcine at 400℃ in a muffle furnace for 2 hours to obtain Ag-ETS-10, marked as a comparative sample.

[0081] The Ag content of the obtained comparative sample is 22.7 wt %, and the specific surface area of ​​the obtained material is as follows: Figure 2 As shown, the xenon adsorption capacity of the obtained material at 298K and 10Pa is as follows Figure 3 shown.

[0082] from Figure 2 By comparison, it can be seen that the modified ETS-10 molecular sieves obtained by lanthanum modification, barium exchange and silver loading in Examples 1 to 4 of the present invention have a larger specific surface area than the Ag-ETS-10 in the comparative example. Figure 3 By comparison, it can be seen that the xenon adsorption capacity of the modified ETS-10 molecular sieves obtained by lanthanum modification, barium exchange and silver loading in Examples 1 to 4 of the present invention is higher than that of the Ag-ETS-10 in the comparative example.

[0083] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A modified titanium silicon molecular sieve, characterized in that: It includes an ETS-10 molecular sieve as a carrier and La, Ba and Ag supported on the ETS-10 molecular sieve; In the modified titanium silicon molecular sieve, the atomic ratio of silicon to titanium is 4.5-5.5, the mass percentage of La is 0.1%-6.0%, the mass percentage of Ba is 0.1%-10.0%, and the mass percentage of Ag is 0.1%-15.0%; The specific surface area of ​​the modified titanium silicalite is 250 m 2 / g~500m 2 / g.

2. The modified titanium silicon molecular sieve according to claim 1, characterized in that: The particle size of the modified titanium silicate molecular sieve is 2 mm to 5 mm.

3. The modified titanium silicon molecular sieve according to claim 1, characterized in that: In the modified titanium silicon molecular sieve, the mass percentage of La is 1.0% to 4.0%, the mass percentage of Ba is 0.1% to 8.0%, and the mass percentage of Ag is 6.0% to 15.0%.

4. The modified titanium silicon molecular sieve according to claim 1, characterized in that: The Ag in the modified titanium silicalite molecular sieve exists in the form of one or more of silver ions, silver atoms, silver nanoclusters and silver nanoparticles for exchange.

5. The modified titanium silicon molecular sieve according to any one of claims 1 to 4, characterized in that: The specific surface area of ​​the modified titanium silicon molecular sieve after calcination in air at 450°C for 2 hours is greater than 300 m 2 / g.

6. The modified titanium silicon molecular sieve according to any one of claims 1 to 4, characterized in that: The modified titanium silicalite molecular sieve has a xenon adsorption capacity greater than 5.0 ml / ml at 298K and 10 Pa.

7. A method for preparing the modified titanium silicon molecular sieve according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1. Synthesis of lanthanum-modified ETS-10 molecular sieve: mixing sulfuric acid solution with anatase titanium oxide and ball-milling to form a uniform titanium oxide slurry; mixing titanium oxide slurry, silicon source, sodium hydroxide, potassium hydroxide, lanthanum salt and potassium fluoride, stirring to form a uniform sol, placing the sol in a high-pressure reactor and reacting at 220° C. for 48 h to 72 h, filtering, washing and drying, and then calcining at 300° C. to 550° C. for 1 h to 4 h to obtain a lanthanum-modified ETS-10 molecular sieve; S2, barium-modified ETS-10 molecular sieve: according to the weight ratio of barium nitrate solution to lanthanum-modified ETS-10 molecular sieve of 10 to 60, the lanthanum-modified ETS-10 molecular sieve is placed in 0.05 mol / L to 0.5 mol / L barium nitrate solution for exchange for 1h to 2h, and the exchange temperature is 30°C to 45°C; after filtering, washing and drying, the barium-modified ETS-10 molecular sieve is obtained; S3. Silver loading: 0.001 mol / L to 0.5 mol / L silver salt solution is loaded onto the barium-modified ETS-10 molecular sieve by equal volume impregnation, and the silver loading amount is adjusted according to the predetermined silver loading amount by the concentration of the silver salt solution. After drying at 80°C to 120°C for 2 to 12 hours, a silver-loaded ETS-10 molecular sieve precursor is obtained; the silver-loaded ETS-10 molecular sieve precursor is calcined at 300°C to 550°C for 2 hours to 4 hours, and pressed into tablets to form a granular modified titanium silicalite molecular sieve.

8. The method for preparing the modified titanium silicon molecular sieve according to claim 7, characterized in that: In step S1, the molar ratio of the substances in the sol is as follows: SiO2:TiO2:Na2O:K2O:F - :La:H2O=4.5~6.5:1:2~8:0.5~3:0.2~1.0:0.01~0.18:120~180; In the sol, the molar ratio of SiO2 to (Na2O+K2O) is 1-2, and the molar ratio of Na2O to K2O is 1.5-9.

9. The method for preparing the modified titanium silicon molecular sieve according to claim 7, characterized in that: In step S1, the silicon source includes at least one of sodium silicate, silica sol, and fumed silica; In step S3, the silver salt is at least one of silver nitrate and silver acetate.

10. Use of the modified titanium silicon molecular sieve according to any one of claims 1 to 6, characterized in that: Used for rapid capture and separation of xenon in gaseous effluents from nuclear power plants and ambient air.

Images