Hierarchical pore SSZ-13 confined high-dispersion Y / MnO2 catalyst as well as preparation method and application of hierarchical pore SSZ-13 confined high-dispersion Y / MnO2 catalyst

Abstract

The invention relates to a hierarchical pore SSZ-13 confined high-dispersion Y-doped MnO2-based catalyst as well as a preparation method and application thereof, and belongs to the technical field of catalysts applied to catalytic oxidation of VOCs (Volatile Organic Compounds). The Y / MnO2-coated H-SSZ-13 catalyst prepared by the method disclosed by the invention is benefited from the confinement effect of the carrier hierarchical pore SSZ-13 and has a relatively large specific surface area and relatively good hydrothermal stability, meanwhile, the active component Y / MnO2 is small in size and is highly dispersed in the SSZ-13, and the reaction frequency on a unit active site is remarkably improved. In addition, doping of the Y element improves the electronic chemical environment of MnO2, oxygen vacancies on Y / MnO2 are rich, the oxygen mobility is improved, and the oxidation-reduction capacity is greatly improved. The doping and loading process is simple, the catalyst performance is high, and the catalyst can be widely applied to catalytic oxidation of organic pollutant gas discharged in the fields of chemical industry, automobile exhaust, coating solvents and the like.

Description

Technical Field

[0001] The present invention relates to a hierarchically porous SSZ-13-confined highly dispersed Y / MnO2 catalyst, a preparation method and an application thereof, belonging to the technical field of catalysts for VOCs catalytic oxidation. Background Art

[0002] Volatile organic compounds (VOCs) are a major air pollutant, posing serious hazards to human health and environmental quality. In recent years, the country has formulated increasingly strict VOCs emission regulations, and VOCs control and treatment technologies are urgently in need of optimization. The catalytic oxidation method is a technology for removing VOCs with broad application prospects. In this technology, building an environmentally friendly catalyst with a low activation temperature, high intrinsic activity and selectivity has become a bottleneck problem to be solved.

[0003] Transition metal oxide catalysts have attracted much attention due to their low cost, strong anti-poisoning and anti-sintering properties. Among them, MnO x has various crystal phases (such as β-MnO2, γ-MnO2, α-Mn2O3 and δ-MnO2) and multi-dimensional structures (such as one-dimensional tunnel structure, two-dimensional layered structure and three-dimensional spinel phase), and has been proven to be a catalyst with high stability, high activity and low cost. The multi-valence state characteristics of manganese elements endow manganese oxides with good redox ability. In addition, the formation of lattice defects in MnO x is beneficial to the generation of oxygen vacancies, promotes oxygen adsorption and the migration of lattice oxygen, effectively improves the low-temperature redox ability and selectivity of the catalyst, and thus makes it have unique advantages and application prospects in the fields of catalytic oxidation of organic pollutants and oxygen chain combustion. However, at the same time, high activation temperature and low CO2 selectivity are still problems faced by manganese-based oxide catalysts.

[0004] At present, the research on metal oxide catalysts mainly focuses on bulk materials. However, the turnover frequency of the catalytic oxidation reaction on the unit active component of the bulk catalyst is low, and the carbon deposition generated during the oxidation process will cover the active sites, causing the catalyst to deactivate during long-term operation and reducing its lifespan. J.J. Wang et al. pre-loaded various metal oxides (such as CeO2, TiO2 and MnO xUltra-small particles such as are encapsulated in zeolites to improve the dispersion of active components. In the catalytic oxidation reaction of toluene, the composite catalyst of this scheme shows good selectivity and thermal stability (Chemistry of Materials, 2018, No. 30, 6361-6369). Improving the dispersion of active components can expose more active sites. Loading metal oxides in porous molecular sieves with adjustable pore sizes is an effective method to obtain small-scale particles. SSZ-13 molecular sieve has a controllable pore structure, a high specific surface area and excellent thermal stability, providing rich dispersion sites for active components. The unique pore structure of the molecular sieve also helps to slow down the aggregation of active components during long-term operation and plays a certain role in inhibiting carbon deposition. Therefore, the construction of a catalyst based on hierarchically porous SSZ-13 loaded with highly dispersed metal oxides and the modification of MnO2 doped with yttrium metal are an implementable technical solution with broad application prospects in the field of VOCs catalytic oxidation. Summary of the Invention

[0005] The object of the present invention is to provide a hierarchically porous SSZ-13-confined highly dispersed Y-doped MnO2-based catalyst, which has good low-temperature catalytic oxidation activity for VOCs and CO2 selectivity.

[0006] To achieve the above object, the technical solution provided by the present invention is as follows:

[0007] A hierarchically porous SSZ-13-confined highly dispersed Y-doped MnO2-based catalyst, the general formula of which is represented by Y / MnO2@H-SSZ-13.

[0008] Wherein H-SSZ-13 is a hierarchically porous molecular sieve after alkali treatment and ion exchange.

[0009] Preferably, the average mesopore diameter of H-SSZ-13 is 10-15 nm.

[0010] Preferably, the specific surface area of Y / MnO2@H-SSZ-13 is 350-400 m 2 / g.

[0011] Preferably, the loading amount of Y / MnO2 is 10-20 wt.%.

[0012] The present invention also provides a preparation method of Y / MnO2@H-SSZ-13 of the above scheme, including the following steps:

[0013] (1), Add Na-SSZ-13 to a NaOH solution with a concentration of 0.05-0.5 mol / L, then stir for 6-24 h, then centrifuge to complete solid-liquid separation, wash the obtained solid with deionized water 3-6 times, and dry it in an oven at 50-100 °C to obtain hierarchically porous Na-SSZ-13.

[0014] (2) Add the hierarchically porous Na-SSZ-13 obtained in step (1) into an NH4NO3 solution with a concentration of 0.5 - 2 mol / L, then stir for 12 - 48 h, and then centrifuge to complete solid-liquid separation. The obtained solid is washed with deionized water 3 - 6 times and dried in an oven at 50 - 100 °C. After drying, the solid is placed in a muffle furnace for calcination to obtain the product H-SSZ-13.

[0015] (3) Add the H-SSZ-13 obtained in step (2) into a mixed solution containing dissolved MnSO4 and Y(NO3)3 (or soluble yttrium salts such as YCl3, Y2(SO4)3, etc.), then stir for 15 - 60 min, ultrasonicate for 1 - 3 h, and dry in a vacuum oven at 50 - 100 °C for 6 - 12 h.

[0016] (4) Add the solid obtained in step (3) into a 0.007 - 0.015 mol / L KMnO4 solution, and successively carry out stirring, hydrothermal treatment at high temperature, centrifugation, washing with deionized water 3 - 6 times, drying, and calcination to obtain the Y / MnO2@H-SSZ-13 catalyst.

[0017] Preferably, in step (1), the stirring temperature is 75 - 85 °C and the drying time is 8 - 24 h.

[0018] Preferably, in step (2), the stirring temperature is 75 - 85 °C, the stirring time is 12 h, the calcination temperature is 500 - 600 °C, and the calcination time is 6 - 10 h.

[0019] Preferably, in step (3), the molar ratio of the raw materials Y(NO3)3·6H2O (or soluble yttrium salts such as YCl3, Y2(SO4)3, etc.) and MnSO4·H2O in the mixed solution is 4:6 - 6:4.

[0020] Preferably, in step (4), the stirring temperature is 25 °C, the stirring time is 15 - 60 min, the hydrothermal temperature is 160 °C, the hydrothermal time is 8 - 16 h, the drying temperature is 60 °C, the drying time is 12 h, the calcination temperature is 400 - 450 °C, and the calcination time is 2 - 3 h.

[0021] The present invention also provides the application of the Y / MnO2@H-SSZ-13 catalyst prepared by the above scheme in the catalytic oxidation of VOCs. The effective results of the present invention are as follows:

[0022] The present invention uses the co-impregnation method to successfully confine yttrium-doped MnO2 in the pores of a hierarchically porous SSZ-13.

[0023] The catalyst Y / MnO2@H-SSZ-13 prepared by the present invention has active components with a small scale and high dispersion. The loading amount of Y / MnO2 is only 15 wt.%, but it has high catalytic oxidation activity for toluene and n-butylamine, with a reduced reaction activation temperature, high selectivity for the product carbon dioxide, a significantly increased chemical reaction frequency per unit active component, and stable physical and chemical properties during long-term operation, and no obvious decrease in activity.

[0024] The Y / MnO2@H-SSZ-13 provided by the present invention has both rich microporous and mesoporous structures, a large specific surface area, good hydrothermal stability, and good oxygen storage capacity. The doping of Y element improves the electrochemical environment of MnO2. Y / MnO2@H-SSZ-13 is rich in oxygen vacancies, the oxygen migration rate is increased, and the redox ability is greatly improved.

[0025] The doping and loading process of the present invention is simple, and the catalyst has high performance, which is very suitable for the field of catalytic oxidation of organic pollutant gases. Description of the Drawings

[0026] Figure 1 It is the XRD pattern of the catalysts in Examples 1 to 3 of the present invention;

[0027] Figure 2 It is the transmission electron microscope pattern of the catalyst in Example 1 of the present invention;

[0028] Figure 3 It is the conversion rate diagram of the catalysts in Examples 1 to 3 of the present invention for catalytic oxidation of toluene at different temperatures;

[0029] Figure 4 It is the conversion rate diagram of the catalyst in Example 1 of the present invention for catalytic oxidation of n-butylamine at different temperatures;

[0030] Figure 5 It is the XRD pattern of the catalysts in Comparative Example 1 and Example 1 of the present invention;

[0031] Figure 6 It is the conversion rate diagram of the catalysts in Comparative Example 1 and Example 1 of the present invention for catalytic oxidation of toluene at different temperatures;

[0032] Figure 7 It is the selectivity diagram of carbon dioxide in the catalytic oxidation of toluene by the catalysts in Comparative Example 1 and Example 1 of the present invention at different temperatures;

[0033] Figure 8 It is the conversion rate diagram of the catalysts in Comparative Example 2 and Example 1 of the present invention for catalytic oxidation of toluene at different temperatures;

[0034] Figure 9 It is the conversion rate diagram of the catalysts in Comparative Example 3 and Example 1 of the present invention for catalytic oxidation of toluene at different temperatures. Detailed implementation manners

[0035] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0036] The present invention provides a preparation method of a hierarchically porous SSZ-13-confined highly dispersed Y / MnO2 catalyst (Y / MnO2@H-SSZ-13) and its application in the catalytic oxidation of VOCs. The detailed implementation manners will be introduced in detail in combination with the embodiments and the accompanying drawings.

[0037] The catalyst provided by the present invention includes an active component Y / MnO2 and a support H-SSZ-13. The preparation method of the support H-SSZ-13 provided by the present invention is consistent in the present technical invention, and different preparation schemes of the loaded active component Y / MnO2 will be further described in the embodiments and comparative examples of the present invention.

[0038] The present invention provides a preparation method of the support H-SSZ-13, and the specific steps are as follows:

[0039] (1) Prepare microporous Na-SSZ-13 by hydrothermal synthesis. Using N,N,N-trimethyl-1-adamantylammonium hydroxide (TMAda-OH) as a template agent, aluminum sulfate octadecahydrate (Al2(SO4)2·18H2O) as an aluminum source, silica sol (30.5 wt.% SiO2) as a silicon source, and sodium hydroxide (NaOH) as a base source. The molar composition of the reaction mixture is as follows: 5TMAda-OH:20Na2O:1Al2O3:30SiO2:1200H2O. The specific synthesis steps are as follows: First, add 1.25 g of NaOH to 20 mL of deionized water and stir to dissolve it. Then weigh 2.082 g of Al2(SO4)2·18H2O and add it to the above alkaline solution, and continue to stir for 1 h until it is clear. Mark this mixed solution as solution A; Then, add 13.2 g of TMAda-OH to 25 mL of deionized water, stir to mix evenly, add 18.445 g of silica sol to the above solution, and stir until the solution is clear and mark it as solution B; Next, add solution A dropwise to solution B and stir at room temperature for 12 h. Transfer the mixed gel to a high-pressure reaction kettle with a polytetrafluoroethylene lining and place it in a homogeneous reactor, and crystallize at 160 °C for 96 h. After the reaction is completed, centrifuge to separate the solid product, wash it with deionized water multiple times until it is neutral, and then dry it at 60 °C. Finally, calcine the dried solid at 550 °C for 8 h to remove the template agent, and the obtained product is microporous Na-SSZ-13.

[0040] (2) Preparation of hierarchical pore Na-SSZ-13 catalyst by post-treatment with alkali solution. The Na-SSZ-13 obtained in step (1) was added to 0.1 mol / L NaOH solution and magnetically stirred at 80 °C for 16 h. The resulting product was centrifuged and washed with deionized water several times until neutral, and then dried at 60 °C. The obtained sample was hierarchical pore Na-SSZ-13.

[0041] (3) Preparation of hierarchical pore H-SSZ-13 by ion exchange method. Weigh 3 g of the hierarchical pore Na-SSZ-13 prepared in step (2) and add it to 100 mL of NH4NO3 solution with a concentration of 1 mol / L. Then stir at 80 °C for 12 h, centrifuge the precipitate, wash it with deionized water until neutral, and dry it at 60 °C. Finally, calcine the dried solid at 550 °C for 8 h, and the resulting product is the support H-SSZ-13.

[0042] The present invention provides the application of the catalyst in the field of catalytic oxidation of toluene. The specific scheme is as follows:

[0043] The catalytic oxidation activity test of the catalyst for toluene was carried out in an atmospheric fixed-bed reactor. Toluene vapor was generated by a -5 °C constant-temperature bubbling device and introduced into 10 mL·min -1 of N2, and the gas volume was controlled by a mass flow meter. The catalyst was pressed into tablets, passed through a 60-80 mesh sieve, and the mass was preferably 50 mg. The total flow rate of the reaction gas was 50 mL·min -1 , and the weight hourly space velocity (WHSV) was 60,000 mL·g -1 ·h -1 . Preferably, the composition of the reaction gas was: 1000 ppm toluene, 21% O2 and 79% N2. Before each test for temperature programming, the catalyst was pretreated in the reaction atmosphere at 90 °C for 4 h to avoid deviation in the toluene conversion rate due to adsorption. The gas composition was automatically monitored by a gas chromatograph (GC, Agilent 8860). The conversion rate of toluene was given by formula (Equation 1):

[0044]

[0045] In the formula, C inlet and C outlet were the concentrations of toluene in the inlet gas and the outlet gas, respectively. Let T 90 represent the temperature when the toluene conversion rate reached 90%.

[0046] The selectivity of CO2 was given by formula (Equation 2):

[0047]

[0048] In the formula, CCO2 is the concentration of CO2 in the outlet gas.

[0049] The present invention provides the application of a catalyst in the field of catalytic oxidation of n-butylamine (abbreviated as NBA), and the specific scheme is as follows:

[0050] The catalytic oxidation activity test of the catalyst for n-butylamine was carried out in a fixed-bed reactor under atmospheric pressure. 100 mg of the catalyst (60-80 mesh) was placed in a quartz tube with a diameter of 5 mm. The WHSV was maintained at 60000 mL·g -1 ·h -1 , the feed gas contained 1000 ppm of n-butylamine and 5 vol% of O2, balanced with argon. The composition of the outlet gas was automatically monitored by a gas chromatograph (GC, Agilent 8860). The conversion of n-butylamine was given by formula (Equation 3):

[0051]

[0052] In the formula, [NBA] inlet and [NBA] outlet are the concentrations of n-butylamine in the inlet and outlet gases, respectively.

[0053] The catalyst provided by the present invention will be further described below in conjunction with examples. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and cannot be used to limit the protection scope of the present invention.

[0054] Example 1, Preparation method and application of a Y / MnO2@H-SSZ-13 catalyst.

[0055] First, 0.137 mmol of MnSO4·H2O and 0.137 mmol of Y(NO3)3·6H2O solids were added to 20 mL of deionized water, stirred and dissolved, then 1 g of H-SSZ-13 was added, and after stirring for 30 min, the mixture was placed in a microwave ultrasonic instrument and ultrasonicated for 3 h. The obtained mixture was placed in a vacuum oven at 80 °C and dried for 8 h. The obtained solid was added to 60 mL of KMnO4 solution, stirred at 25 °C for 30 min, then the liquid was transferred to a 100 mL polytetrafluoroethylene-lined autoclave and reacted at 160 °C for 12 h. The solid product was centrifuged and washed 3 times with deionized water, and the obtained solid was placed in a vacuum oven and dried at 80 °C. The dried product was placed in a muffle furnace and calcined at 400 °C for 2 h. The obtained sample was a Y / MnO2@H-SSZ-13 catalyst with n(Mn 2+ ) / n(Y 3+ ) = 1:1.

[0056] 50 mg of the catalyst was placed in a fixed-bed reactor for the catalytic oxidation activity test of toluene. Preferably, the composition of the reaction gas was: 1000 ppm toluene, 21% O2 and 79% N2. The weight hourly space velocity (WHSV) of the reaction gas was 60,000 mL·g -1 ·h -1 . The test temperature range was 50 - 400 °C.

[0057] 100 mg of the catalyst was placed in a fixed-bed reactor for the catalytic oxidation activity test of n-butylamine. Preferably, the weight hourly space velocity (WHSV) of the reaction gas was maintained at 60000 mL·g -1 ·h -1 , the feed gas contained 1000 ppm of n-butylamine and 5 vol% of O2, balanced with argon. The test temperature range was 100 - 450 °C.

[0058] Example 2, a preparation method and application of a Y / MnO2@H-SSZ-13 catalyst.

[0059] First, 0.11 mmol of MnSO4·H2O and 0.164 mmol of Y(NO3)3·6H2O solids were added to 20 mL of deionized water and stirred until dissolved. Then, 1 g of H-SSZ-13 was added, and after stirring for 30 min, the mixture was placed in a microwave ultrasonic instrument and sonicated for 3 h. The resulting mixture was placed in a vacuum oven at 80 °C and dried for 8 h. The obtained solid was added to 60 mL of KMnO4 solution, stirred at 25 °C for 30 min, and then the liquid was transferred to a 100 mL polytetrafluoroethylene-lined autoclave and reacted at 160 °C for 12 h. The solid product was centrifuged and washed 3 times with deionized water, and the obtained solid was placed in a vacuum oven and dried at 80 °C. The dried product was placed in a muffle furnace and calcined at 400 °C for 2 h. The obtained sample was a Y / MnO2@H-SSZ-13 catalyst with n(Mn 2+ ) / n(Y 3+ ) = 4:6.

[0060] 50 mg of the catalyst was placed in a fixed-bed reactor for the catalytic oxidation activity test of toluene. Preferably, the composition of the reaction gas was: 1000 ppm toluene, 21% O2 and 79% N2. The total flow rate of the reaction gas was 50 mL·min -1 , and the corresponding weight hourly space velocity (WHSV) was 60,000 mL·g -1 ·h -1 . The test temperature range was 50 - 400 °C.

[0061] Example 3, a preparation method and application of a Y / MnO2@H-SSZ-13 catalyst.

[0062] First, 0.164 mmol of MnSO4·H2O and 0.11 mmol of Y(NO3)3·6H2O solids were added to 20 mL of deionized water and stirred until dissolved. Then, 1 g of H-SSZ-13 was added, and after stirring for 30 min, the mixture was sonicated in a microwave ultrasonic instrument for 3 h. The resulting mixture was placed in a vacuum oven at 80 °C and dried for 8 h. The obtained solid was added to 60 mL of KMnO4 solution, stirred at 25 °C for 30 min, and then the liquid was transferred to a 100 mL polytetrafluoroethylene-lined autoclave and reacted at 160 °C for 12 h. The solid product was centrifuged and washed three times with deionized water, and the obtained solid was dried in vacuo at 80 °C. The dried product was placed in a muffle furnace and calcined at 400 °C for 2 h. The obtained sample was the Y / MnO2@H-SSZ-13 catalyst with n(Mn 2+ ) / n(Y 3+ ) = 6:4.

[0063] 50 mg of the catalyst was placed in a fixed-bed reactor for the catalytic oxidation activity test of toluene. Preferably, the composition of the reaction gas was: 1000 ppm toluene, 21% O2, and 79% N2. The total flow rate of the reaction gas was 50 mL·min -1 , and the gas mass hourly space velocity (WHSV) was 60,000 mL·g -1 ·h -1 . The test temperature range was 50 - 400 °C.

[0064] Figure 1 This is the XRD pattern of the catalysts in Examples 1 - 3 of the present invention. The diffraction peaks that appeared at 2θ = 9.5°, 14.0°, 16.1°, 17.8°, 20.7°, 25°, and 30.7° for both samples belong to the characteristic peaks of SSZ-13, corresponding to the (101), (110), (021), (003), (211), (104), and (312) crystal planes of SSZ-13, respectively. It shows that the active components Y / MnO2 may be mostly distributed in the internal pores of the molecular sieve and are relatively small in size and cannot be detected by XRD, and the introduction of manganese and yttrium does not change the crystal structure of the molecular sieve.

[0065] Figure 2 This is the transmission electron micrograph of the catalyst in Example 1 of the present invention. From Figure 2 (a), it can be seen that the size of Y / MnO2@H-SSZ-13 is about 500 - 600 nm. At the same time, it can be seen that Y / MnO2 in the sample exists in the form of ultrathin flaky morphology, and no large oxide particles are found on the surface of the carrier. As the magnification of the electron microscope increases, as Figure 2 (b) shows, obvious lattice fringes appear, and the interplanar spacing is The part corresponds to the (101) crystal plane of SSZ-13. In addition, as shown in Figure 2 (c), it can also be detected that the crystal plane spacing corresponds to which belongs to the MnO2(-111) crystal plane.

[0066] Figure 3 This is the catalytic oxidation activity diagram of the catalysts in Examples 1-3 of the present invention in the range of 50-400 °C. Y / MnO2@H-SSZ-13 shows good catalytic activity, where the catalyst T 2+ ) / n(Y 3+ ) = 1:1 90 is 232 °C.

[0067] Figure 4 This is the catalytic oxidation activity diagram of the catalyst in Example 1 of the present invention for n-butylamine in the range of 100-450 °C. The catalyst Y / MnO2@H-SSZ-13 shows a high conversion rate of n-butylamine. When the temperature is higher than 220 °C, the conversion rate of n-butylamine can reach more than 90%.

[0068] Comparative Example 1, a preparation method and application of a MnO2@H-SSZ-13 catalyst.

[0069] First, 0.0464 g of MnSO4·H2O was dissolved in 20 mL of deionized water, then 1 g of H-SSZ-13 was added, and after stirring for 30 min, it was transferred to a microwave ultrasonic instrument and ultrasonicated for 3 h. The ultrasonicated mixture was vacuum dried at 80 °C for 12 h. Then the dried solid was added to 60 mL of KMnO4 solution and stirred for 30 min. Subsequently, the mixture was transferred to a high-pressure reaction kettle and subjected to static hydrothermal reaction at 160 °C for 12 h. The solid product was centrifuged and washed with deionized water multiple times, and then vacuum dried at 80 °C for 12 h. Finally, the dried solid was placed in a muffle furnace and calcined at 400 °C for 2 h to obtain the MnO2@H-SSZ-13 catalyst.

[0070] 50 mg of the catalyst was placed in a fixed-bed reactor for the catalytic oxidation activity test of toluene. Preferably, the composition of the reaction gas was: 1000 ppm toluene, 21% O2 and 79% N2. The total flow rate of the reaction gas was 50 mL·min -1 , and the gas mass hourly space velocity (WHSV) was 60,000 mL·g -1 ·h -1 . The test temperature range was 50-400 °C.

[0071] Comparative Example 2, a preparation method and application of a Y / MnO2@H-SSZ-13 catalyst.

[0072] First, 1.37*10 -4mol of MnSO4·H2O and 1.37*10 -4 mol of Y(NO3)3·6H2O solids were added to 20 mL of deionized water, stirred until dissolved, then 1 g of H-SSZ-13 was added, and after stirring for 30 min, the mixture was placed in a microwave ultrasonic instrument and ultrasonicated for 3 h. The resulting mixture was placed in a vacuum oven at 80 °C and dried for 8 h. The obtained solid was added to 60 mL of KMnO4 solution, stirred at 25 °C for 30 min, then the liquid was transferred to a 100 mL polytetrafluoroethylene-lined autoclave and reacted statically at 160 °C for 12 h. The solid product was centrifuged and washed 3 times with deionized water, and the obtained solid was placed in a vacuum oven and dried at 80 °C. The dried product was placed in a muffle furnace and calcined at 450 °C for 3 h. The obtained sample was Y / MnO2@H-SSZ-13 catalyst with n(Mn 2+ ) / n(Y 3+ ) = 1:1 and the calcination conditions of 450 °C for 3 h.

[0073] 50 mg of the catalyst was placed in a fixed-bed reactor for the catalytic oxidation activity test of toluene. Preferably, the composition of the reaction gas was: 1000 ppm toluene, 21% O2 and 79% N2. The total flow rate of the reaction gas was 50 mL·min -1 , and the gas mass hourly space velocity (WHSV) was 60,000 mL·g -1 ·h -1 . The test temperature range was 50 - 400 °C.

[0074] Comparative Example 3, a preparation method and application of a Y / MnO2@H-SSZ-13 catalyst.

[0075] First, 0.0464 g of MnSO4·H2O was dissolved in 20 mL of deionized water, and then 1 g of H-SSZ-13 was added. After stirring for 30 min, it was transferred to a microwave ultrasonic instrument and ultrasonicated for 3 h. The ultrasonicated mixture was dried in vacuo at 80 °C for 12 h. Then the dried solid was added to 60 mL of KMnO4 solution and stirred for 30 min. Subsequently, the mixture was transferred to a high-pressure reactor and subjected to static hydrothermal reaction at 160 °C for 12 h. The solid product was centrifuged and washed repeatedly with deionized water, and then dried in vacuo at 80 °C for 12 h. Finally, the dried solid was placed in a muffle furnace and calcined at 400 °C for 2 h to obtain the MnO2@H-SSZ-13 catalyst. Secondly, 1 g of the MnO2@H-SSZ-13 catalyst was added to 100 mL of 0.1 M Y(NO3)3 solution. Then it was mechanically stirred at 80 °C for 8 h. The solid product was centrifuged and washed 3 times with deionized water, and dried at 60 °C. Then it was calcined at 400 °C for 2 h, and the obtained sample was the Y-MnO2@H-SSZ-13 catalyst prepared by the ion exchange method.

[0076] 50 mg of the catalyst was placed in a fixed-bed reactor for the catalytic oxidation activity test of toluene. Preferably, the composition of the reaction gas was: 1000 ppm toluene, 21% O2 and 79% N2. The total flow rate of the reaction gas was 50 mL·min -1 , and the gas mass hourly space velocity (WHSV) was 60,000 mL·g -1 ·h -1 . The test temperature range was 50 - 400 °C.

[0077] Figure 5 This is the XRD pattern of the catalyst of Comparative Example 1 and Example 1 of the present invention. Both samples showed the characteristic diffraction peaks of SSZ-13 at positions such as 2θ = 9.5°, 14.0°, 16.1°, 17.8°, 20.7°, 25° and 30.7°. In addition, compared with MnO2@H-SSZ-13, the diffraction intensity of the characteristic peaks of Y / MnO2@H-SSZ-13 was significantly weakened, probably due to the high dispersion and absorption of X-rays by Y / MnO2 on the zeolite. Particularly, for the (101) crystal plane corresponding to 2θ = 9.5°, its intensity was significantly weakened in Y / MnO2@H-SSZ-13, and the diffraction peak corresponding to the (211) crystal plane was the strongest, which may indicate that the loading mainly occurred on the (101) crystal plane. Compared with MnO2@H-SSZ-13, the position of the characteristic diffraction peaks of Y / MnO2@H-SSZ-13 did not change significantly, and no additional diffraction peaks appeared, indicating that yttrium doping did not change the crystal structure of the zeolite.

[0078] Figure 6The conversion rate of toluene during the catalytic oxidation of toluene by the catalyst of Comparative Example 1 and Example 1 of the present invention in the range of 50-400 °C. According to Figure 6 It can be seen that in the range of 100-200 °C, the conversion rate of toluene on Y / MnO2@H-SSZ-13 is at least 40% higher than that on MnO2@H-SSZ-13. This indicates that the doping of Y in the Y / MnO2@H-SSZ-13 catalyst improves the redox ability of the catalyst and is beneficial to the oxidation of toluene.

[0079] Figure 7 The selectivity of carbon dioxide during the catalytic oxidation of toluene by the catalyst of Comparative Example 1 and Example 1 of the present invention in the range of 50-400 °C. According to Figure 7 It can be seen that the selectivity of carbon dioxide on Y / MnO2@H-SSZ-13 is better than that on MnO2@H-SSZ-13.

[0080] Figure 8 The conversion rate of toluene during the catalytic oxidation of toluene by the catalyst of Comparative Example 2 and Example 1 of the present invention at 50-400 °C. According to Figure 8 It can be seen that the calcination temperature has a certain influence on the catalytic activity of the catalyst. In the present invention, Y / MnO2@H-SSZ-13 with a calcination condition of 400 °C / 2 h exhibits better low-temperature activity.

[0081] Figure 9 The conversion rate of toluene during the catalytic oxidation of toluene by the catalyst of Comparative Example 3 and Example 1 of the present invention at 50-400 °C. According to Figure 9 It can be seen that different doping processes will affect the catalytic activity after yttrium modification. In the toluene catalytic oxidation test, the activity of the Y-doped MnO2@SSZ-13 catalyst prepared by the ion exchange method is significantly lower than that of the Y / MnO2@H-SSZ-13 catalyst prepared by the co-impregnation method in Example 1 throughout the test temperature range, and its T 90 is 285 °C, which is about 50 °C higher than the latter.

[0082] From the above examples and comparative examples, it can be seen that the Y / MnO2@H-SSZ-13 catalyst provided by the present invention has high catalytic activity for VOCs, simple preparation steps, and certain environmental and economic benefits.

[0083] Although the above description has made a detailed description of the present invention, it is only a part of the preferred embodiments of the present invention. For those skilled in the art, changes and improvements can also be made according to the description of the present invention, and these changes all fall within the protection scope of the present invention.

Claims

1. A multi - porous SSZ - 13 confined highly - dispersed Y - doped MnO₂ - based catalyst, characterized in that, It is represented by the general formula Y / MnO₂@H - SSZ - 13; it includes a multi - porous support and uniformly - distributed active components; The support is H - SSZ - 13; the active component is yttrium - doped manganese oxide, represented by Y / MnO₂; The H - SSZ - 13 is a multi - porous molecular sieve after alkali treatment and ion exchange; The average pore diameter of the mesopores of the H - SSZ - 13 is 10 - 15 nm; The specific surface area of the Y / MnO2@H-SSZ-13 is 350-400 m 2 / g; The loading amount of the active component Y / MnO₂ is 10 - 15 wt.%.

2. The preparation method of the hierarchically porous SSZ-13-confined highly dispersed Y-doped MnO2-based catalyst according to claim 1, characterized in that, It includes the following steps: (1) Add Na - SSZ - 13 to a NaOH solution with a concentration of 0.05 - 0.5 mol / L, then stir for 6 - 24 h, and then centrifuge to complete solid - liquid separation. The obtained solid is washed with deionized water 3 - 6 times and dried in an oven at 50 - 100 °C to obtain multi - porous Na - SSZ - 13; (2) Add the multi - porous Na - SSZ - 13 obtained in step (1) to an NH₄NO₃ solution with a concentration of 0.5 - 2 mol / L, then stir for 12 - 48 h, and then centrifuge to complete solid - liquid separation. The obtained solid is washed with deionized water 3 - 6 times and dried in an oven at 50 - 100 °C. The dried solid is placed in a muffle furnace for calcination to obtain H - SSZ - 13; (3) Add the H - SSZ - 13 obtained in step (2) to a mixed solution containing MnSO₄ and Y(NO₃)₃, then stir for 15 - 60 min, ultrasonicate for 1 - 3 h, and dry in a vacuum oven at 50 - 100 °C for 6 - 12 h; (4) Add the solid obtained in step (3) to a KMnO₄ solution with a concentration of 0.007 - 0.015 mol / L, and successively carry out stirring, high - temperature hydrothermal treatment, centrifugation, washing with deionized water 3 - 6 times, drying and calcination to obtain the Y / MnO₂@H - SSZ - 13 catalyst.

3. The preparation method of the hierarchically porous SSZ-13-confined highly dispersed Y-doped MnO₂-based catalyst according to claim 2, wherein, In step (1), the stirring temperature is 75 - 85 °C and the drying time is 8 - 24 h.

4. The preparation method of the hierarchically porous SSZ-13-confined highly dispersed Y-doped MnO2-based catalyst according to claim 2, characterized in that, In step (2), the stirring temperature is 75 - 85 °C, the stirring time is 12 h, the calcination temperature is 500 - 600 °C, and the calcination time is 6 - 10 h.

5. The preparation method of the hierarchically porous SSZ-13-confined highly dispersed Y-doped MnO2-based catalyst according to claim 2, wherein, In step (3), the molar ratio of the raw materials of the mixed solution, the soluble yttrium salt Y(NO₃)₃·6H₂O and MnSO₄·H₂O, is 4:6 - 6:

4.

6. The preparation method of the hierarchically porous SSZ-13-confined highly dispersed Y-doped MnO2-based catalyst according to claim 2, characterized in that, In step (4), the stirring temperature is 25 °C, the stirring time is 15 - 60 min, the hydrothermal temperature is 160 °C, the hydrothermal time is 8 - 16 h, the drying temperature is 60 °C, the drying time is 12 h, the calcination temperature is 400 - 450 °C, and the calcination time is 2 - 3 h.

7. The preparation method of the hierarchically porous SSZ-13-confined highly dispersed Y-doped MnO2-based catalyst according to claim 2 or 5, characterized in that, Y(NO₃)₃·6H₂O can be replaced by soluble yttrium salts such as YCl₃ and Y₂(SO₄)₃.

8. The application of the multi - porous SSZ - 13 confined highly - dispersed Y - doped MnO₂ catalyst according to claim 1 or the Y / MnO₂@H - SSZ - 13 catalyst obtained by the preparation method according to any one of claims 2 - 6 in the catalytic oxidation of VOCs.

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