BiOCl / USY composite catalyst and application thereof in VUV-PCO purification of VOCs
By using the BiOCl/USY composite catalyst in the VUV-PCO system, the problem of insufficient catalyst utilization efficiency for 254nm ultraviolet light and ozone was solved, achieving efficient degradation of VOCs and effective removal of ozone, and reducing the health risks of byproducts.
Patent Information
- Application Number
- CN202511015634.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-23
- Publication Date
- 2025-11-04
AI Technical Summary
In existing VUV-PCO technology, the catalysts have difficulty making efficient use of 254nm ultraviolet light and generated ozone, which limits the catalytic oxidation performance and may generate harmful byproducts, thus restricting its practical application.
A BiOCl/USY composite catalyst was used, in which BiOCl was loaded onto USY molecular sieve to form a catalyst with abundant mesoporous structure and acidic sites, which synergistically utilized 254nm ultraviolet light and ozone for VOCs degradation.
It significantly improves the degradation efficiency of VOCs and the removal rate of ozone, reduces the health risk index of by-products to a safe range, and achieves efficient and deep degradation and mineralization of VOCs.
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Figure CN120885261A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of catalyst materials, in particular to a BiOCl / USY composite catalyst and its application in VUV-PCO purification of VOCs. BACKGROUND
[0002] As a typical atmospheric pollutant, volatile organic compounds (VOCs) not only pose a direct threat to human health due to their volatile, toxic and chemically active characteristics, but also exacerbate atmospheric pollution problems by forming secondary pollutants such as ozone and PM2.5 through photochemical reactions. Under the background of accelerating industrialization and urbanization, the emission of VOCs continues to rise, which has become a key factor affecting environmental quality and public health. Currently, VOCs treatment technology is facing major challenges. Although traditional methods such as activated carbon adsorption, catalytic combustion and low-temperature plasma have certain effects under certain conditions, they generally have defects such as high energy consumption, complex process and possible secondary pollution. Therefore, there is an urgent need to develop green and efficient VOCs treatment technology.
[0003] Photocatalysis technology is attracting attention in the field of VOCs degradation due to its environmental characteristics, broad applicability, mild reaction conditions and sustainability. However, this technology still faces many bottlenecks in practical application, such as insufficient catalyst stability, low degradation efficiency for structurally stable VOCs, and possible generation of harmful intermediates, which restrict its industrialization and popularization.
[0004] Vacuum ultraviolet (VUV) catalytic oxidation as a new type of advanced oxidation technology uses 185nm and 254nm ultraviolet light generated by VUV light source, the former can directly crack VOCs molecular bonds, and the latter can generate active oxygen (such as ·OH and ·O2 - ) by exciting air components, thereby promoting the degradation of pollutants. VUV-PCO technology promotes the deep degradation of pollutants by synergizing VUV photolysis and catalytic oxidation processes, using the original 254nm ultraviolet light and O3 generated in the system. However, the VUV-PCO system still faces many challenges, the most critical of which is that existing catalysts cannot efficiently utilize 254nm ultraviolet light and O3 generated in the system, resulting in limited catalytic oxidation performance, difficulty in complete mineralization of byproducts, and easy generation of toxic byproducts, which pose potential risks to the environment and human health, thereby limiting its practical application. SUMMARY
[0005] The purpose of the present application is to provide a BiOCl / USY composite catalyst and its application in VUV-PCO purification of VOCs to solve the problems existing in the prior art.
[0006] To achieve the above object, the present application provides the following scheme:
[0007] One of the technical solutions of the present application is a preparation method of a BiOCl / USY composite catalyst, comprising the following steps:
[0008] The solution of the chlorine source is added to the mixed solution of the USY molecular sieve and the bismuth source, and the BiOCl / USY composite catalyst is obtained after heat reaction.
[0009] Further, the solvent used in the mixed solution of the USY molecular sieve and the bismuth source includes ethanol and glycerol.
[0010] The volume ratio of the ethanol and glycerol is (0.1-10):1.
[0011] Further, the volume ratio of the ethanol and glycerol is (2-3):1.
[0012] Further, the solvent used in the solution of the chlorine source includes ethanol.
[0013] Further, the molar ratio of SiO2 and Al2O3 in the USY molecular sieve is (20-500):1, which is a high-silicon aluminum ratio USY molecular sieve.
[0014] Further, the molar ratio of the bismuth source and the USY molecular sieve (the molar amount of the USY molecular sieve is calculated based on the molar amount of Al2O3) is (0.01-10):1.
[0015] Further, the molar ratio of the bismuth source and the USY molecular sieve is (0.2-0.5):1.
[0016] Further, the molar ratio of the chlorine source and the bismuth source is (1-5):1.
[0017] Further, the molar ratio of the chlorine source and the bismuth source is (1-3):1.
[0018] Further, the temperature of the heat reaction is 100-200℃, and the time is 20-28h.
[0019] Further, the temperature of the heat reaction is 170-200℃, and the time is 20-24h.
[0020] Further, the bismuth source includes one or two of Bi2(SO4)3, BiI3 and Bi(NO3)3·5H2O.
[0021] Further, the chlorine source includes at least one of NaCl, KCl and NH4Cl.
[0022] Further, the steps of cooling, centrifugation, washing and drying treatment are further included after the heat reaction.
[0023] The drying treatment comprises vacuum drying, and the temperature is 50-100 DEG C, and the time is 8-24h.
[0024] Further, the temperature is 60-80 DEG C, and the time is 10-20h.
[0025] Bismuth oxychloride (BiOCl) has special crystal face arrangement (tetragonal structure, composed of [Bi2O2] 2+ Cation layer and Cl - Anion layer) and electronic properties (p-type semiconductor), and strong built-in electric field effect (the layered structure of BiOCl will form built-in electric field in the direction perpendicular to the sheet layer), which can effectively promote the separation of photo-generated carriers and improve the catalytic efficiency.
[0026] USY molecular sieve has large specific surface area and rich acid sites (the increase of specific surface area can significantly increase the number of available adsorption active sites on the surface of the material; and the acid sites as the key active center play an important role in the adsorption and catalytic reaction process), and has good hydrophobicity, and is suitable for practical application scenarios.
[0027] The application uses USY molecular sieve as the carrier of the catalyst, realizes the regulation of the specific surface area of the catalyst, and introduces acid sites, so that the photocatalytic activity, pollutant adsorption capacity and ozone synergistic catalytic oxidation performance are significantly improved through the electronic interaction between the catalyst and the carrier.
[0028] The second technical scheme of the application: a BiOCl / USY composite catalyst prepared by the above preparation method.
[0029] The third technical scheme of the application: application of the above BiOCl / USY composite catalyst in VUV-PCO purification of VOCs.
[0030] Further, the VOCs include low-concentration VOCs.
[0031] The fourth technical scheme of the application: a VUV-PCO system for catalytic oxidation of VOCs, comprising the above BiOCl / USY composite catalyst.
[0032] The fifth technical scheme of the application: a construction method of the above VUV-PCO system for catalytic oxidation of VOCs, comprising the following steps:
[0033] The BiOCl / USY composite catalyst is loaded on the foamed nickel to obtain a foamed nickel loaded BiOCl / USY composite catalyst, and then the foamed nickel loaded BiOCl / USY composite catalyst is placed in a VUV-PCO reactor to obtain the VUV-PCO system for catalytic oxidation of VOCs.
[0034] The foamed nickel acts as a carrier and plays a supporting role.
[0035] The foamed nickel loaded BiOCl / USY composite catalyst prepared in the application adopts USY molecular sieves with a SiO2 / Al2O3 molar ratio of 20-500 as a carrier, and the abundant mesoporous structure and acid sites of the USY molecular sieves make the specific surface area of the composite catalyst reach about 400 m 2 / g, which is about 20 times that of pure BiOCl, and can greatly improve the adsorption capacity of the catalyst for pollutants.
[0036] The foamed nickel loaded BiOCl / USY composite catalyst prepared in the application can synergistically utilize 254 nm ultraviolet light and O3 to realize efficient and deep degradation and mineralization of VOCs, so that the health risk index (HRI) of byproducts is reduced to below 1, and the O3 concentration of the system emission is effectively controlled, fully meeting the indoor air quality safety requirements.
[0037] The application discloses the following technical effects:
[0038] (1) The BiOCl / USY composite catalyst prepared in the application can overcome the defects of the photocatalytic materials used in the existing VUV-PCO technology, such as insufficient synergistic utilization efficiency of 254 nm ultraviolet light and ozone (O3), high recombination rate of photo-generated carriers, and limited ozone catalytic oxidation performance.
[0039] (2) In the preparation process of the foamed nickel loaded BiOCl / USY composite catalyst, partial dealumination occurs to form abundant mesoporous structures, so that the specific surface area of the composite catalyst reaches about 20 times (i.e., 400 m 2 / g) that of pure BiOCl.
[0040] BiOCl presents an uneven distribution on the USY surface, part of the particles are uniformly dispersed, and part of the particles are in an aggregated state, and a strong electronic interaction is formed between the two, photo-generated electrons can migrate from BiOCl to USY under irradiation, and the carrier separation efficiency is significantly improved.
[0041] The composite catalyst retains the oxygen vacancies (OVs) of BiOCl and the acid sites of USY, and the synergistic effect of the two can significantly improve the ozone catalytic oxidation performance.
[0042] (3) The application realizes the comprehensive improvement of the performance of the VUV-PCO system through unique carrier selection and structural design, and the toluene degradation efficiency can reach 94%.
[0043] (4) The VUV-PCO system of the foam nickel loaded BiOCl / USY composite catalyst can nearly completely control the emission of ozone, and the ozone removal rate is increased by 41% compared with that of the pure USY catalyst. In the removal cycle stability test, after 8h of reaction, the toluene removal rate and mineralization rate of the foam nickel loaded BiOCl / USY composite catalyst of the application remain above 80%, and the O3 removal rate is about 80%, which provides a reliable solution for the practical application of the VUV-PCO technology in the treatment of low-concentration VOCs in industry and life. BRIEF DESCRIPTION OF DRAWINGS
[0044] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.
[0045] Figure 1 SEM images of the foam nickel loaded BiOCl / USY composite catalyst (i.e., BiOCl / USY) prepared for Example 5, the foam nickel loaded commercial USY catalyst (i.e., USY) prepared for Comparative Example 1, and the foam nickel loaded BiOCl-ST catalyst (i.e., BiOCl-ST) prepared for Comparative Example 3, wherein (a) and (b) are BiOCl-ST, (c) and (d) are USY, and (e) and (f) are BiOCl / USY;
[0046] Figure 2 XRD patterns of the foam nickel loaded BiOCl / USY composite catalyst (i.e., BiOCl / USY) prepared for Example 5, the foam nickel loaded commercial USY catalyst (i.e., USY) prepared for Comparative Example 1, and the foam nickel loaded BiOCl-ST catalyst (i.e., BiOCl-ST) prepared for Comparative Example 3;
[0047] Figure 3 N2 adsorption-desorption isotherms and pore size distribution of the foam nickel loaded BiOCl / USY composite catalyst (i.e., BiOCl / USY) prepared for Example 5, the foam nickel loaded commercial USY catalyst (i.e., USY) prepared for Comparative Example 1, and the foam nickel loaded BiOCl-ST catalyst (i.e., BiOCl-ST) prepared for Comparative Example 3, wherein (a) is the N2 adsorption-desorption isotherm, and (b) is the pore size distribution;
[0048] Figure 4 The catalytic oxidation effects of different reaction processes on VOCs exhaust gas, wherein (a) is the change of toluene concentration at the outlet of the VUV-PCO reactor with time, (b) is the toluene removal rate after 120 min of reaction, (c) is the CO generated by toluene oxidation x with time, (d) is the CO generated by toluene oxidation after 120 min of reaction x selectivity, (e) is the change of O3 concentration at the outlet of the VUV-PCO reactor with time, (f) is the O3 removal rate after 120 min of reaction;
[0049] Figure 5 The results of the cyclic stability test of the foam nickel supported BiOCl / USY composite catalyst prepared in Example 5;
[0050] Figure 6 The NH3-TPD graphs of the foam nickel supported BiOCl / USY composite catalyst (i.e., BiOCl / USY) prepared in Example 5, the foam nickel supported commercial USY catalyst (i.e., USY) of Comparative Example 1, and the foam nickel supported BiOCl-ST catalyst (i.e., BiOCl-ST) prepared in Comparative Example 2;
[0051] Figure 7 The effects of different reaction processes on the health-related index (HRI) are compared. DETAILED DESCRIPTION
[0052] Various illustrative embodiments of the present application are now described in detail below. The detailed description provided herein is not intended to be exhaustive or to limit the application to the precise form disclosed. While specific embodiments of, and examples for, the application are described herein for illustrative purposes, various equivalent alterations and modifications will become apparent to those skilled in the relevant art and are included within the scope of this application.
[0053] It should be understood that the terms used herein are merely descriptive, but that the application should not be limited to the particular embodiments described. In addition, for numerical ranges, it is to be understood that every numerical value within the range is specifically included. The upper and lower limits of these smaller ranges are also independently specifically included within the scope of the application. The upper and lower limits of these smaller ranges can independently be included or excluded in the range.
[0054] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application, the preferred methods and materials are described. All patents, patent applications, publications, and descriptions mentioned herein are incorporated by reference to disclose and describe the methods and / or materials in connection with which the patents, patent applications, publications, and descriptions are cited. In case of conflict, the contents of the present specification will control.
[0055] Many modifications and variations of the present application described herein will be apparent to those skilled in the art in light of the foregoing disclosure. Other implementations of the present application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. The specification and examples given are exemplary only.
[0056] As used herein, the terms "comprise", "comprising", "include", "including", "have", "having" and the like are open-ended and do not exclude additional elements or steps.
[0057] It should be noted that the present application does not describe in detail the conventional means in the art, and is not the focus of the present application.
[0058] Example 1
[0059] A method for preparing a BiOCl / USY composite catalyst for efficient photocatalysis-ozone synergistic catalysis:
[0060] (1) 0.80 g of USY molecular sieve (molar ratio of SiO2 to Al2O3 is 110-130:1) was dispersed in 30 mL of anhydrous ethanol-glycerol mixed solvent (volume ratio of anhydrous ethanol to glycerol is 2:1) and stirred uniformly.
[0061] (2) 0.09 g of Bi(NO3)3·5H2O was added to the solution of step (1) and stirred until completely dissolved to obtain solution A.
[0062] (3) 0.02 g of NH4Cl was dissolved in 10 mL of organic solvent to obtain solution B.
[0063] (4) Solution B was slowly added to solution A and transferred to a reaction kettle for hydrothermal reaction (temperature is 200°C and time is 20 h).
[0064] (5) After cooling, the product was collected by centrifugation, washed, and vacuum dried (temperature is 80°C and time is 10 h) to obtain the BiOCl / USY composite catalyst.
[0065] The support of the BiOCl / USY composite catalyst prepared in this example is USY molecular sieve, and the active component is BiOCl. The mass of BiOCl was determined and calculated to be 10 wt% of the total mass of BiOCl and USY.
[0066] Example 2
[0067] A method for preparing a BiOCl / USY composite catalyst for efficient photocatalysis-ozone synergistic catalysis:
[0068] (1) 0.80 g of USY molecular sieve (molar ratio of SiO2 to Al2O3 is 110-130:1) was dispersed in 30 mL of anhydrous ethanol-glycerol mixed solvent (volume ratio of anhydrous ethanol to glycerol is 2:1) and stirred uniformly.
[0069] (2) 0.38 g of Bi(NO3)3·5H2O was added to the solution of step (1) and stirred until completely dissolved to obtain solution A.
[0070] (3) 0.04 g of NH4Cl was dissolved in 10 mL of organic solvent to obtain solution B.
[0071] (4) Solution B was slowly added to solution A and transferred to a reaction kettle for hydrothermal reaction (temperature is 200°C and time is 20 h).
[0072] (5) The product was collected by centrifugation, washed, and vacuum dried (temperature is 80°C and time is 10 h) to obtain a BiOCl / USY composite catalyst.
[0073] The support of the BiOCl / USY composite catalyst prepared in this example is USY molecular sieve, and the active component is BiOCl. The mass of BiOCl was determined and calculated to be 20 wt% of the total mass of BiOCl and USY.
[0074] Example 3
[0075] A preparation method of a high-efficiency photocatalysis-ozone synergistic BiOCl / USY composite catalyst:
[0076] (1) 0.80 g of USY molecular sieve (molar ratio of SiO2 to Al2O3 is 110-130:1) was dispersed in 30 mL of anhydrous ethanol-glycerol mixed solvent (volume ratio of anhydrous ethanol to glycerol is 2:1) and stirred uniformly.
[0077] (2) 0.64 g of Bi(NO3)3·5H2O was added to the solution of step (1) and stirred until completely dissolved to obtain solution A.
[0078] (3) 0.07 g of NH4Cl was dissolved in 10 mL of organic solvent to obtain solution B.
[0079] (4) Solution B was slowly added to solution A and transferred to a reaction kettle for hydrothermal reaction (temperature is 200°C and time is 20 h).
[0080] (5) The product was collected by centrifugation, washed, and vacuum dried (temperature is 80°C and time is 10 h) to obtain a BiOCl / USY composite catalyst.
[0081] The support of the BiOCl / USY composite catalyst prepared in the example is USY molecular sieve, and the active component is BiOCl. The mass of BiOCl is 30wt% of the total mass of BiOCl and USY.
[0082] Example 4
[0083] A method for constructing a VUV-PCO system for catalytic oxidation of VOCs:
[0084] The BiOCl / USY composite catalyst prepared in Example 1 is loaded on foamed nickel to obtain a foamed nickel loaded BiOCl / USY composite catalyst, and then the foamed nickel loaded BiOCl / USY composite catalyst is placed in a VUV-PCO reactor for testing. The foamed nickel loading operation is as follows:
[0085] After ultrasonic dispersion of 0.2g of catalyst in 15mL of ethanol, the mixture is uniformly coated on foamed nickel with the same size as the length and width of the VUV-PCO reactor cavity, the mixture is completely absorbed, and the catalyst loading is 0.2g after drying at 60℃.
[0086] Example 5
[0087] A method for constructing a VUV-PCO system for catalytic oxidation of VOCs:
[0088] The BiOCl / USY composite catalyst prepared in Example 2 is loaded on foamed nickel to obtain a foamed nickel loaded BiOCl / USY composite catalyst, and then the foamed nickel loaded BiOCl / USY composite catalyst is placed in a VUV-PCO reactor for testing. The foamed nickel loading operation is the same as in Example 4.
[0089] Example 6
[0090] A method for constructing a VUV-PCO system for catalytic oxidation of VOCs:
[0091] The BiOCl / USY composite catalyst prepared in Example 3 is loaded on foamed nickel to obtain a foamed nickel loaded BiOCl / USY composite catalyst, and then the foamed nickel loaded BiOCl / USY composite catalyst is placed in a VUV-PCO reactor for testing. The foamed nickel loading operation is the same as in Example 4.
[0092] Comparative Example 1
[0093] A method for constructing a VUV-PCO system for catalytic oxidation of VOCs:
[0094] A commercially available USY molecular sieve (molar ratio of SiO2 and Al2O3 is 110-130:1) was loaded on a foamed nickel to obtain a foamed nickel loaded commercially available USY catalyst, and then the foamed nickel loaded commercially available USY catalyst was placed in a VUV-PCO reactor for testing. The foamed nickel loading operation is as follows:
[0095] 0.20 g of USY molecular sieve was dissolved in 15 mL of anhydrous ethanol, and after ultrasonic dispersion, the mixture was uniformly coated on a foamed nickel with the same size as the cavity of the VUV-PCO reactor, and the mixture was completely absorbed and dried at 60°C. The loading amount of the USY molecular sieve was 0.2 g.
[0096] Comparative Example 2
[0097] A method for constructing a VUV-PCO system for catalytic oxidation of VOCs:
[0098] A BiOCl-ST catalyst was loaded on a glass sheet to obtain a glass sheet loaded BiOCl-ST catalyst, and then the glass sheet loaded BiOCl-ST catalyst was placed in a VUV-PCO reactor for testing. The preparation method of the catalyst and the glass sheet loading operation are as follows:
[0099] (1) 0.38 g of Bi(NO3)3·5H2O was dispersed in 30 mL of anhydrous ethanol-glycerol mixed solvent (volume ratio of anhydrous ethanol and glycerol was 2:1) and stirred until completely dissolved to obtain solution A.
[0100] (2) 0.04 g of NH4Cl was dissolved in 10 mL of organic solvent to obtain solution B.
[0101] (3) Solution B was slowly added to solution A, and then transferred to a reaction kettle for hydrothermal reaction (temperature was 200°C, and time was 20 h).
[0102] (4) The product was collected by centrifugation, washed, and vacuum dried (temperature was 80°C, and time was 10 h) to obtain the BiOCl-ST catalyst.
[0103] 0.1 g of the catalyst was dissolved in 4 mL of ethanol and ultrasonically dispersed, and the mixture was uniformly dropped onto a glass sheet with the same size as the cavity of the VUV-PCO reactor, and dried at 60°C. The loading amount of the catalyst was 0.1 g.
[0104] Comparative Example 3
[0105] A method for constructing a VUV-PCO system for catalytic oxidation of VOCs:
[0106] The BiOCl-ST catalyst was loaded on the nickel foam to obtain a nickel foam loaded BiOCl-ST catalyst, and then the nickel foam loaded BiOCl-ST catalyst was placed in a VUV-PCO reactor for testing. The preparation method of the catalyst and the loading operation of the nickel foam are as follows:
[0107] (1) 0.38 g of Bi(NO3)3·5H2O was dispersed in 30 mL of anhydrous ethanol-glycerol mixed solvent (the volume ratio of anhydrous ethanol and glycerol was 2:1) and stirred until completely dissolved to obtain solution A.
[0108] (2) 0.04 g of NH4Cl was dissolved in 10 mL of organic solvent to obtain solution B.
[0109] (3) Solution B was slowly added to solution A, and then transferred to a reaction kettle for hydrothermal reaction (the temperature was 200°C, and the time was 20 h).
[0110] (4) The product was collected by centrifugation, washed, and vacuum dried (the temperature was 80°C, and the time was 10 h) to obtain the BiOCl-ST catalyst.
[0111] 0.20 g of BiOCl-ST catalyst was dissolved in 15 mL of anhydrous ethanol, and after ultrasonic dispersion, the mixed solution was uniformly coated on the nickel foam with the same size as the long and VUV-PCO reactor cavity, the mixed solution was completely absorbed, and the BiOCl-ST catalyst was dried at 60°C. The loading amount of the BiOCl-ST catalyst was 0.2 g.
[0112] Comparative Example 4
[0113] A method for constructing a VUV-PCO system for catalytic oxidation of VOCs:
[0114] The TiO2 / USY composite catalyst was loaded on the nickel foam to obtain a nickel foam loaded TiO2 / USY composite catalyst, and then the nickel foam loaded TiO2 / USY composite catalyst was placed in a VUV-PCO reactor for testing. The preparation method of the catalyst and the loading operation of the nickel foam are as follows:
[0115] (1) 1.20 g of commercially available USY molecular sieve (the molar ratio of SiO2 and Al2O3 was 110-130:1) was added to 10 mL of anhydrous ethanol and stirred uniformly.
[0116] (2) 1.3 mL of tetrabutyl titanate, 0.1 mL of concentrated hydrochloric acid and 0.03 mL of acetic acid acetone were added to the suspension and stirred uniformly to obtain solution A.
[0117] (3) 1 mL of deionized water was added to 1 mL of anhydrous ethanol and mixed thoroughly to obtain solution B.
[0118] (4) Solution B was added dropwise into solution A under vigorous stirring and the stirring was continued until a gel was formed.
[0119] (5) The gel was dried in an oven at 100°C for 10h, then transferred to a muffle furnace and calcined at 550°C for 5h to obtain TiO2 / USY composite catalyst.
[0120] 0.20g TiO2 / USY composite catalyst was dissolved in 15mL anhydrous ethanol, after ultrasonic dispersion, the mixture was uniformly coated on the foam nickel with the same size as the VUV-PCO reactor cavity, the mixture was completely absorbed, and dried at 60°C, the loading amount of TiO2 / USY composite catalyst was 0.2g.
[0121] Comparative Example 5
[0122] A method for preparing a BiOCl / SBA-15 catalyst and loading it on a glass sheet:
[0123] (1) 2g P123 was dissolved in 80mL 1.6M hydrochloric acid aqueous solution at 40°C, after complete dissolution, 4.5mL tetraethyl orthosilicate was slowly added, and stirred at 40°C for 24h, then transferred to a polytetrafluoroethylene liner and hydrothermally crystallized at 100°C for 24h. After the crystallized suspension was centrifuged and washed with deionized water for several times, it was dried at room temperature for 72h and then ground into powder. Then the powder was calcined at 400°C for 5h to obtain the SBA-15 carrier.
[0124] (2) Preparation of BiOCl / SBA-15 composite catalyst: 2.5g bismuth nitrate pentahydrate was added to 20mL glacial acetic acid containing 0.325g SBA-15, stirred for 30min, then 10mL aqueous solution containing 0.2675g ammonium chloride was added dropwise, stirred for 5min, then the white suspension was transferred to a hydrothermal kettle and hydrothermally crystallized at 180°C for 24h. Finally, the BiOCl / SBA-15 catalyst was obtained by centrifugation and washing with deionized water for several times and drying at 60°C (the mass percentage of SBA-15 in BiOCl / SBA-15 was 20%).
[0125] 0.1g BiOCl / SBA-15 catalyst was dissolved in 4mL ethanol and ultrasonically dispersed, the mixture was uniformly dropped onto a glass sheet with the same size as the VUV-PCO reactor cavity, and dried at 60°C, the loading amount of the catalyst was 0.1g.
[0126] Example 1
[0127] The SEM images of the foam nickel supported BiOCl / USY composite catalyst (i.e. BiOCl / USY) prepared in Example 5, the foam nickel supported commercial USY catalyst (i.e. USY) prepared in Comparative Example 1 and the foam nickel supported BiOCl-ST catalyst (i.e. BiOCl-ST) prepared in Comparative Example 3 are shown in Figure 1 , wherein (a) and (b) are BiOCl-ST, (c) and (d) are USY, and (e) and (f) are BiOCl / USY.
[0128] It can be seen from Figure 1 that in the BiOCl / USY composite catalyst, because the size of the BiOCl crystal grains is significantly larger than the pore size of the USY molecular sieve, the BiOCl cannot enter the micropores of the USY and mainly exists in the form of surface loading. The BiOCl shows a characteristic of uneven distribution on the surface of the USY, in which part of the particles are uniformly dispersed and part of the particles form an aggregated state.
[0129] The XRD test results of the foam nickel supported BiOCl / USY composite catalyst (i.e. BiOCl / USY) prepared in Example 5, the foam nickel supported commercial USY catalyst (i.e. USY) prepared in Comparative Example 1 and the foam nickel supported BiOCl-ST catalyst (i.e. BiOCl-ST) prepared in Comparative Example 3 are shown in Figure 2 .
[0130] It can be seen from Figure 2 that all the samples have sharp diffraction peaks, showing good crystallinity.
[0131] The N2 adsorption-desorption isotherms and pore size distributions of the foam nickel supported BiOCl / USY composite catalyst (i.e. BiOCl / USY) prepared in Example 5, the foam nickel supported commercial USY catalyst (i.e. USY) prepared in Comparative Example 1 and the foam nickel supported BiOCl-ST catalyst (i.e. BiOCl-ST) prepared in Comparative Example 3 are shown in Figure 3 , wherein (a) is the N2 adsorption-desorption isotherm and (b) is the pore size distribution.
[0132] It can be seen from Figure 3As can be seen, pure BiOCl-ST presents type IV isotherm, while the isotherm shape of BiOCl / USY is similar to that of USY, both of which show rapid increase in adsorption capacity at low relative pressure (P / P0) and then tend to be stable (type I isotherm), corresponding to microporous adsorption behavior. The specific surface area determination results show that the specific surface area of each catalyst is in the order of USY > BiOCl / USY > BiOCl-ST. And the specific surface area of BiOCl / USY composite catalyst is significantly higher than that of BiOCl-ST, which has abundant microporous and mesoporous structure, and larger specific surface area not only provides more surface adsorption sites, but also enhances the interaction between the catalyst and the reactant molecules, thereby promoting the improvement of photocatalytic and ozone catalytic degradation efficiency.
[0133] Effect Example 2
[0134] The catalytic oxidation effects of different VUV-PCO systems for catalyzing VOCs in the test examples and comparative examples on VOCs waste gas and the catalytic oxidation effect of VOCs waste gas without catalyst (control group) were determined, and the results are shown in Table 1 and Figure 4 .
[0135] Figure 4 VUV in Table 1 is the control group, VUV+USY is Comparative Example 1, VUV+BiOCl-ST is Comparative Example 3, VUV+30B90U is Example 6, VUV+BiOCl / USY is Example 5, and VUV+10B90U is Example 4.
[0136] A continuous flow photocatalytic oxidation system was used. The VUV-PCO reactor was composed of a quartz tube photolysis module (10 W) with a VUV lamp and a cuboid catalytic reaction module. The 254 nm ultraviolet light emitted by the VUV lamp was irradiated onto the surface of the catalyst through the quartz glass window. The total flow rate of the reaction gas was controlled at 1 L·min -1 , the concentration of toluene was 20 ppm, the relative humidity was 50%, and the reaction temperature was maintained at room temperature (25℃). The reaction gas first passed through the VUV photolysis module and then entered the catalytic reaction module, where further oxidation reactions occurred under the combined action of the catalyst, 254 nm ultraviolet light and O3.
[0137] Figure 4 (a) in Table 1 is the change of toluene concentration at the outlet of the VUV-PCO reactor with time, (b) is the toluene removal rate after 120 min of reaction, (c) is the change of CO x concentration generated by toluene oxidation with time, (d) is the CO x selectivity of toluene oxidation after 120 min of reaction, (e) is the change of O3 concentration at the outlet of the VUV-PCO reactor with time, and (f) is the O3 removal rate after 120 min of reaction.
[0138] Table 1. Specific detection results of toluene degradation after 120 min
[0139]
[0140] From Table 1 and Figure 4 , it can be seen that the BiOCl / USY (20% BiOCl / 80% USY) composite catalyst performs best in toluene removal rate, CO x selectivity and O3 removal rate.
[0141] Example 3
[0142] The results of the cycle stability test of the foam nickel supported BiOCl / USY composite catalyst prepared in Example 5 (the test method is the same as above) are shown in Figure 5 .
[0143] From Figure 5 , it can be seen that the performance stability of the BiOCl / USY composite catalyst during multiple uses, after 480 minutes of reaction, the toluene removal rate and mineralization rate remain above 80%, and the O3 removal rate is about 80%.
[0144] Example 4
[0145] The NH3-TPD graphs of the foam nickel supported BiOCl / USY composite catalyst (i.e. BiOCl / USY) prepared in Example 5, the foam nickel supported commercial USY catalyst (i.e. USY) of Comparative Example 1, and the foam nickel supported BiOCl-ST catalyst (i.e. BiOCl-ST) prepared in Comparative Example 3 are shown in Figure 6 .
[0146] From Figure 6 , it can be seen that there are obvious differences in the surface acidity of different catalysts. Pure BiOCl-ST has basically no acid sites, while pure USY has both weak acid sites (<300°C) and a small amount of strong acid sites (300-500°C). When BiOCl-ST is loaded on USY, the composite catalyst inherits the acidity characteristics of USY, and has both weak and strong acid sites. These acid sites help to adsorb VOCs molecules, thereby improving the efficiency of subsequent ozone catalytic oxidation reaction.
[0147] Example 5
[0148] The health-related index (HRI) is used to evaluate the risk of byproducts produced during toluene degradation to human health, and the lower the value represents the higher the safety (HRI≤1 is safe). The same method as in Example 2 was used to measure the VOCs exhaust gas after 2h of catalytic oxidation, and the health-related index (HRI) was calculated, and the results are shown in Figure 7 .
[0149] FromFigure 7 As can be seen, the HRI of VUV photolysis process is the highest and the health risk is the greatest; the HRI is reduced after adding BiOCl-ST, but still exceeds the safety limit; and the HRI is reduced to 0.62 by using BiOCl / USY composite catalyst, indicating that the composite catalyst can effectively realize safe degradation of toluene and the by-products are harmless to human body.
[0150] The above-described embodiments are only to illustrate the preferred modes of the present application, and are not intended to limit the scope of the present application, and various modifications and improvements to the technical solutions of the present application made by those skilled in the art without departing from the design spirit of the present application shall fall within the protection scope defined by the claims of the present application.
Claims
1. A method for preparing a BiOCl / USY composite catalyst, characterized in that, Includes the following steps: A solution of chlorine source was added to a mixed solution of USY molecular sieve and bismuth source, and the BiOCl / USY composite catalyst was obtained after thermal reaction.
2. The preparation method according to claim 1, characterized in that, The solvent used in the mixed solution of the USY molecular sieve and bismuth source includes ethanol and glycerol; And / or, the volume ratio of ethanol to glycerol is (0.1–10):1; And / or, the solvent used in the solution of the chlorine source includes ethanol.
3. The preparation method according to claim 1, characterized in that, The molar ratio of SiO2 to Al2O3 in the USY molecular sieve is (20-500):
1.
4. The preparation method according to claim 1, characterized in that, The molar ratio of the bismuth source to the USY molecular sieve is (0.01–10):
1.
5. The preparation method according to claim 1, characterized in that, The molar ratio of the chlorine source to the bismuth source is (1-5):
1.
6. The preparation method according to claim 1, characterized in that, The temperature of the thermal reaction is 100–200°C, and the time is 20–28 hours.
7. A BiOCl / USY composite catalyst prepared by the preparation method according to any one of claims 1 to 6.
8. The application of the BiOCl / USY composite catalyst according to claim 7 in VUV-PCO purification of VOCs.
9. A VUV-PCO system for catalytic oxidation of VOCs, characterized in that, Including the BiOCl / USY composite catalyst as described in claim 7.
10. A method for constructing the VUV-PCO system for catalytic oxidation of VOCs as described in claim 9, characterized in that, Includes the following steps: The BiOCl / USY composite catalyst was loaded onto nickel foam and then placed in a VUV-PCO reactor to obtain the VUV-PCO system for catalytic oxidation of VOCs.