A Mn-doped BiOCl / SBA-15 composite catalyst and its preparation method and application

Abstract

The present invention relates to a Mn-doped BiOCl / SBA-15 composite catalyst and a preparation method and application thereof, and relates to the technical field of catalyst materials. The composite catalyst comprises a carrier and an active component, wherein the carrier is SBA-15, the active component is Mn-doped BiOCl, the molar ratio of manganese element to bismuth element is at least 0.0005:1, and the mass of SBA-15 is at least 5wt% of the total mass of BiOCl and SBA-15. The Mn-doped BiOCl / SBA-15 composite catalyst of the present invention can effectively improve its catalytic efficiency in VUV catalytic degradation of VOCs, and enhance its performance of catalytic oxidation of VOCs using generated ozone, and can be applied to VUV system catalytic oxidation of continuous flow VOCs waste gas.

Description

Technical Field

[0001] The present invention relates to the technical field of catalyst materials, and more specifically, to a Mn-doped BiOCl / SBA-15 composite catalyst and a preparation method and application thereof. Background Art

[0002] Volatile organic compounds (VOCs) are an important type of air pollutants with the characteristics of high volatility, strong toxicity and high chemical activity. They can directly endanger human health and generate ozone and secondary particulate matter (PM2.5) through photochemical reactions, aggravating complex atmospheric pollution. With the rapid development of industrialization and urbanization, the emission of VOCs has continued to increase and has become an important factor affecting the environment and public health. Efficient control of VOCs has become a major challenge in the field of environmental governance. Traditional VOCs control methods include technologies such as activated carbon adsorption, catalytic combustion and low-temperature plasma. Although these methods are effective in certain specific scenarios, they generally have problems such as high energy consumption, complex operation and easy secondary pollution. Therefore, the development of green and efficient VOCs treatment technology has become an urgent problem to be solved.

[0003] Traditional photocatalytic technology has significant advantages in degrading VOCs, such as environmental friendliness, wide application range, mild operating conditions and sustainability, and can decompose VOCs into harmless carbon dioxide and water. However, its application still has many limitations, such as the catalyst is easy to deactivate in long-term operation, the reaction rate is slow for structurally stable VOCs, and the intermediate products or by-products may be generated to cause secondary pollution, which makes it difficult to meet the needs of actual industrial applications.

[0004] Bismuth oxychloride (BiOCl), as a layered photocatalytic material, has shown great potential in the field of photocatalysis in recent years. Its unique crystal plane arrangement and electronic structure give it a strong built-in electric field, which helps to separate photogenerated electron-hole pairs, thereby improving photocatalytic efficiency. In addition, the surface properties of BiOCl can be adjusted to give it more active sites in pollutant degradation.

[0005] Vacuum ultraviolet (VUV) catalytic oxidation technology is an emerging advanced oxidation technology that uses VUV tubes to emit high-energy ultraviolet light with wavelengths of 185 nm and 254 nm. The ultraviolet light with a wavelength of 185 nm can directly break the chemical bonds in VOCs molecules and stimulate oxygen and water in the air to generate a large number of active oxygen species (such as hydroxyl radicals OH and superoxide radicals O 2 -). Compared with traditional photocatalysis, VUV catalysis has the advantages of strong oxidation ability, broad spectrum applicability and fast reaction rate. However, VUV catalytic technology also has certain limitations. For example, the 254 nm ultraviolet light emitted by the VUV light source is not fully utilized. In addition, the VUV light source will generate high concentrations of ozone, which may cause secondary pollution if not fully utilized. Therefore, how to efficiently utilize 254 nm ultraviolet light and ozone has become an important research direction of VUV catalytic technology.

[0006] Chinese patent CN103316699A discloses a preparation method of a bismuth oxychloride photocatalyst and its particles, which can be used to oxidize a methyl orange aqueous solution and has a high degradation rate of methyl orange under ultraviolet light. However, the prior art does not solve the technical problem of low utilization rate of high-concentration ozone generated during VUV ultraviolet photocatalysis of bismuth oxychloride. Summary of the invention

[0007] The purpose of the present invention is to overcome the defects and shortcomings of the existing BiOCl catalyst in the process of VUV catalytic degradation of VOCs, and to provide a Mn-doped BiOCl / SBA-15 composite catalyst, which can effectively improve its photocatalytic efficiency in VUV catalytic degradation of VOCs and enhance its performance of catalytic oxidation of VOCs using the generated ozone, thereby achieving more efficient and stable VOCs degradation.

[0008] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0009] A Mn-doped BiOCl / SBA-15 composite catalyst comprises a carrier and an active component, wherein the carrier is SBA-15, the active component is Mn-doped BiOCl, the molar ratio of manganese element to bismuth element is at least 0.0005:1, and the mass of SBA-15 is at least 5wt% of the total mass of BiOCl and SBA-15.

[0010] The present invention significantly enhances the electronic conductivity of the catalyst by introducing Mn. Manganese ions act as electron acceptors in the catalytic process, can effectively capture excited electrons, reduce the recombination of electron-hole pairs, and thus improve the efficiency of the photocatalytic reaction. In addition, the Mn element can also improve the reactivity of the catalyst in the ozone catalytic oxidation reaction by promoting the activation and decomposition of ozone molecules during the catalytic process. Mn can interact with ozone molecules to enhance the oxidation ability of ozone, thereby effectively improving the conversion efficiency of ozone in the degradation of VOCs. The dual enhancement effect of enhanced photocatalytic activity under ultraviolet light irradiation and enhanced ozone decomposition ability significantly improves the overall efficiency of the catalyst in the VUV catalytic oxidation of VOCs.

[0011] Since BiOCl is a single photocatalyst, its surface adsorption capacity is weak and it is difficult to effectively adsorb organic pollutants, thereby limiting its catalytic performance. The Mn-doped BiOCl / SBA-15 composite catalyst of the present invention loads BiOCl on the SBA-15 carrier, utilizes the larger specific surface area and regular pore structure of SBA-15, provides more reaction sites for BiOCl, enhances the adsorption capacity of VOCs, and thus improves the degradation efficiency. In addition, the pore structure of SBA-15 can also effectively prevent the agglomeration of BiOCl particles, maintain its dispersibility, and enhance the photocatalytic activity of the catalyst. Through this loading mode, the photogenerated carriers of BiOCl can participate in the reaction more effectively, and the electron transfer efficiency in the catalytic process is improved. At the same time, the high stability of SBA-15 can improve the durability of the catalyst in long-term reactions and extend the service life of the catalyst. In summary, BiOCl is loaded on SBA-15, which not only improves the reaction activity of the catalyst, but also enhances the stability and durability of the catalyst, and significantly improves the degradation performance of VOCs.

[0012] In the present invention, the mass of SBA-15 is 5wt%, 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, and 35wt% of the total mass of BiOCl and SBA-15.

[0013] Preferably, the mass of SBA-15 is 5 wt % to 30 wt % of the total mass of BiOCl and SBA-15.

[0014] More preferably, the mass of SBA-15 is 20 wt % to 30 wt % of the total mass of BiOCl and SBA-15.

[0015] In the present invention, the molar ratio of manganese element to bismuth element may be 0.0005, 0.001, 0.0015, 0.002, 0.0025, 0.003, 0.0035, 0.004, 0.0045, 0.005, 0.0055, or 0.006.

[0016] Preferably, the molar ratio of manganese element to bismuth element is (0.0005-0.005):1.

[0017] More preferably, the molar ratio of manganese element to bismuth element is (0.001-0.003):1.

[0018] Preferably, the specific surface area of ​​the Mn-doped BiOCl / SBA-15 composite catalyst is 70-100 m² / g.

[0019] The composite catalyst of the present invention utilizes the larger specific surface area and regular pore structure of SBA-15 to provide more reaction sites for BiOCl, thereby enhancing the adsorption capacity of VOCs and thus improving the degradation efficiency.

[0020] The present invention also protects a method for preparing the Mn-doped BiOCl / SBA-15 composite catalyst described in any one of the above items, comprising the following steps:

[0021] S1. SBA-15 carrier, bismuth salt and chlorine source were added to glacial acetic acid to obtain BiOCl / SBA-15 composite catalyst by hydrothermal reaction;

[0022] S2. The BiOCl / SBA-15 composite catalyst obtained in step S1 and a soluble manganese salt are mixed and stirred, and dried to obtain a Mn-doped BiOCl / SBA-15 composite catalyst.

[0023] In the present invention, in step S2, the BiOCl / SBA-15 composite catalyst is mixed with a soluble manganese salt, and the pore structure and Si-OH of SBA-15 are stirred to capture manganese ions, thereby obtaining a Mn-doped BiOCl / SBA-15 composite catalyst.

[0024] The Mn-doped BiOCl / SBA-15 composite catalyst prepared by the preparation method of the present invention has a good porous structure and a high specific surface area, and the manganese element can be evenly distributed on the surface and in the pores of the BiOCl / SBA-15 composite catalyst, which significantly improves the photocatalytic and ozone catalytic oxidation activities of the catalyst.

[0025] In the present invention, the bismuth salt is bismuth nitrate pentahydrate.

[0026] In the present invention, the chlorine source can be one or more of ammonium chloride, sodium chloride or potassium chloride.

[0027] In the present invention, in step S2, mixing and stirring can be performed in ethanol.

[0028] In the present invention, the SBA-15 vector can be obtained from the market or can be prepared by oneself.

[0029] For example, the preparation method of the SBA-15 carrier includes the following steps: dissolving the surfactant P123 in a hydrochloric acid aqueous solution, adding tetraethyl orthosilicate, stirring the reaction and then performing hydrothermal crystallization, followed by centrifugal washing, drying and calcining to obtain the SBA-15 carrier.

[0030] Preferably, the specific surface area of ​​the SBA-15 carrier is 800~1200m² / g.

[0031] Preferably, in step S1, the temperature of the hydrothermal reaction is 160-180° C., and the time of the hydrothermal reaction is 20-24 h.

[0032] Preferably, the soluble manganese salt is one of manganese acetate tetrahydrate and manganese sulfate.

[0033] The Mn-doped BiOCl / SBA-15 composite catalyst of the present invention is suitable for vacuum ultraviolet (VUV) catalytic oxidation reactions of various pollutants, and particularly exhibits excellent performance in the field of volatile organic compounds (VOCs) degradation.

[0034] The present invention also protects the use of the Mn-doped BiOCl / SBA-15 composite catalyst described in any one of the above items in the catalytic oxidation of continuous flow VOCs waste gas in a VUV system.

[0035] Preferably, the VOCs are one or more of toluene and chlorobenzene.

[0036] Compared with the prior art, the present invention has the following beneficial technical effects:

[0037] The present invention provides a Mn-doped BiOCl / SBA-15 composite catalyst, which uses SBA-15 as a carrier to provide a porous skeleton structure, and introduces manganese to improve the performance of the BiOCl catalyst. The introduction of SBA-15 not only increases the specific surface area and adsorption capacity of the catalyst, but also enhances the dispersibility of the catalyst and improves the photocatalytic activity. At the same time, the incorporation of manganese can effectively improve the electronic conductivity of the catalyst and enhance the utilization rate of ozone molecules, thereby further improving the catalytic degradation efficiency.

[0038] The Mn-doped BiOCl / SBA-15 composite catalyst of the present invention can effectively improve its catalytic efficiency in VUV catalytic degradation of VOCs and enhance its catalytic performance in ozone catalytic oxidation, and can be applied to VUV system catalytic oxidation of continuous flow VOCs waste gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 The XRD diagrams of the catalysts of Example 1, Comparative Example 1 and Comparative Example 2 are shown in FIG.

[0040] Figure 2 The Raman spectra of the catalysts of Example 1, Comparative Example 1 and Comparative Example 2 are shown.

[0041] Figure 3 (a) is the EPR graph of Example 1 before and after irradiation with VUV light. Figure 3 (b) is a comparison between theoretical simulation and experimental data of the EPR graph of Example 1 before and after irradiation under VUV light.

[0042] Figure 4(a) is the adsorption-desorption curve and specific surface area of ​​the catalysts of Example 1, Comparative Example 1 and Comparative Example 2. Figure 4 (b) shows the adsorption-desorption curve and specific surface area of ​​the SBA-15 carrier.

[0043] Figure 5 (a) is the SEM image of the SBA-15 carrier of Comparative Example 3. Figure 5 (b) is the SEM image of Comparative Example 1. Figure 5 (c) is the SEM image of Comparative Example 2. Figure 5 (d) is the SEM image of Example 1. Figure 5 (e) is the EDX spectrum of the composite catalyst in Example 1.

[0044] Figure 6 This is a diagram of the reaction device for catalytic oxidation of continuous flow VOCs waste gas in the VUV system.

[0045] Figure 7 These are the results of five cycles of composite VOCs degradation testing of the Mn-doped BiOCl / SBA-15 composite catalyst in Example 1 under different humidity conditions. DETAILED DESCRIPTION

[0046] The present invention is further described below in conjunction with specific embodiments, but the embodiments do not limit the present invention in any form. Unless otherwise specified, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents.

[0047] Activated carbon, manufactured by Aladdin, with a specific surface area of ​​1230 m 2 / g.

[0048] Example 1

[0049] A Mn-doped BiOCl / SBA-15 composite catalyst comprises a carrier and an active component, wherein the carrier is SBA-15, the active component is Mn-doped BiOCl, the molar ratio of manganese element to bismuth element is 0.001:1, and the mass of SBA-15 is 20wt% of the total mass of BiOCl and SBA-15.

[0050] The preparation method of the above-mentioned Mn-doped BiOCl / SBA-15 composite catalyst comprises the following steps:

[0051] S1. Dissolve 2 g of P123 in 80 mL of 1.6 M hydrochloric acid solution at 40 °C by stirring. After all the solution is dissolved, slowly add 4.5 mL of tetraethyl orthosilicate, stir at 40 °C for 24 h, and then transfer to a polytetrafluoroethylene liner for hydrothermal crystallization at 100 °C for 24 h. After multiple centrifugation and deionized water washing, the crystallized suspension is dried at room temperature for 72 h and ground into powder. The powder is then calcined at 400 °C for 5 h to finally obtain the SBA-15 carrier.

[0052] Preparation of BiOCl / SBA-15 composite catalyst: Add 2.5 g of bismuth nitrate pentahydrate (i.e., the mass percentage of SBA-15 in BiOCl / SBA-15 is 20%) to 20 mL of glacial acetic acid containing 0.325 g of SBA-15, stir for 30 min, and then add 10 mL of an aqueous solution containing 0.2675 g of ammonium chloride dropwise. After stirring for 5 min, the white suspension was transferred to a hydrothermal autoclave and hydrothermally crystallized at 180 °C for 24 h. Finally, the BiOCl / SBA-15 catalyst was obtained by multiple centrifugal washing with deionized water and drying at 60 °C.

[0053] S2. Preparation of Mn-doped BiOCl / SBA-15 composite catalyst: 0.0013 g of manganese acetate tetrahydrate and 1.625 g of BiOCl / SBA-15 catalyst were added to ethanol and stirred vigorously to make the molar ratio of manganese element to bismuth element be 0.001. After Mn ions were captured by the internal pores of SBA-15 and Si-OH, the mixture was dried at 150 °C for 24 h to obtain Mn-doped BiOCl / SBA-15 catalyst (referred to as Mn / BOC / SBA-15).

[0054] Example 2

[0055] A Mn-doped BiOCl / SBA-15 composite catalyst comprises a carrier and an active component, wherein the carrier is SBA-15, and the active component is Mn-doped BiOCl; the molar ratio of manganese element to bismuth element is 0.001; and the mass of SBA-15 is 5wt% of the total mass of BiOCl and SBA-15.

[0056] The preparation method of the Mn-doped BiOCl / SBA-15 composite catalyst comprises step S1 which is substantially the same as that in Example 1, except that in step S1, 2.5 g of bismuth nitrate pentahydrate is added to 20 mL of glacial acetic acid containing 0.068 g of SBA-15.

[0057] Example 3

[0058] A Mn-doped BiOCl / SBA-15 composite catalyst comprises a carrier and an active component, wherein the carrier is SBA-15, and the active component is Mn-doped BiOCl; the molar ratio of manganese element to bismuth element is 0.001; and the mass of SBA-15 is 10wt% of the total mass of BiOCl and SBA-15.

[0059] The preparation method of the Mn-doped BiOCl / SBA-15 composite catalyst comprises step S1 which is substantially the same as that in Example 1, except that: in step S1, 2.5 g of bismuth nitrate pentahydrate is added to 20 mL of glacial acetic acid containing 0.144 g of SBA-15.

[0060] Example 4

[0061] A Mn-doped BiOCl / SBA-15 composite catalyst comprises a carrier and an active component, wherein the carrier is SBA-15, and the active component is Mn-doped BiOCl; the molar ratio of manganese element to bismuth element is 0.001; and the mass of SBA-15 is 30wt% of the total mass of BiOCl and SBA-15.

[0062] The preparation method of the Mn-doped BiOCl / SBA-15 composite catalyst comprises step S1 which is substantially the same as that in Example 1, except that: in step S1, 2.5 g of bismuth nitrate pentahydrate is added to 20 mL of glacial acetic acid containing 0.557 g of SBA-15.

[0063] Example 5

[0064] A Mn-doped BiOCl / SBA-15 composite catalyst comprises a carrier and an active component, wherein the carrier is SBA-15, the active component is Mn-doped BiOCl, the molar ratio of manganese element to bismuth element is 0.003:1, and the mass of SBA-15 is 20wt% of the total mass of BiOCl and SBA-15.

[0065] The preparation method of the Mn-doped BiOCl / SBA-15 composite catalyst comprises step S1 which is substantially the same as that of Example 1, except that 0.0038 g of manganese acetate tetrahydrate is added so that the molar ratio of manganese element to bismuth element is 0.003.

[0066] Example 6

[0067] A Mn-doped BiOCl / SBA-15 composite catalyst comprises a carrier and an active component, wherein the carrier is SBA-15, the active component is Mn-doped BiOCl, the molar ratio of manganese element to bismuth element is 0.005, and the mass of SBA-15 is 20wt% of the total mass of BiOCl and SBA-15.

[0068] The preparation method of the Mn-doped BiOCl / SBA-15 composite catalyst comprises step S1 which is substantially the same as that of Example 1, except that 0.0063 g of manganese acetate tetrahydrate is added so that the molar ratio of manganese element to bismuth element is 0.005.

[0069] Example 7

[0070] A Mn-doped BiOCl / SBA-15 composite catalyst comprises a carrier and an active component, wherein the carrier is SBA-15, the active component is Mn-doped BiOCl, the molar ratio of manganese element to bismuth element is 0.0005:1, and the mass of SBA-15 is 20wt% of the total mass of BiOCl and SBA-15.

[0071] The preparation method of the Mn-doped BiOCl / SBA-15 composite catalyst comprises step S1 which is substantially the same as that of Example 1, except that 0.0006 g of manganese acetate tetrahydrate is added so that the molar ratio of manganese element to bismuth element is 0.0005.

[0072] Comparative Example 1

[0073] A method for preparing a BiOCl catalyst comprises the following steps:

[0074] 2.5 g of bismuth nitrate pentahydrate was added to 20 mL of glacial acetic acid. After stirring for 30 min, 10 mL of an aqueous solution containing 0.2675 g of ammonium chloride was added dropwise. After stirring for 5 min, the white suspension was transferred to a hydrothermal reactor and hydrothermally crystallized at 180 °C for 24 h. Finally, the catalyst was washed with deionized water by centrifugation several times and dried at 60 °C to obtain the BiOCl catalyst (abbreviated as BOC).

[0075] Comparative Example 2

[0076] A method for preparing a BiOCl / SBA-15 catalyst, which differs from Example 1 in that step S2 is not included (referred to as BOC / SBA-15).

[0077] Comparative Example 3

[0078] A method for preparing an SBA-15 vector is the same as the method for preparing the SBA-15 vector in Example 1.

[0079] Comparative Example 4

[0080] A Mn-doped BiOCl / C composite catalyst comprises a carrier and an active component, wherein the carrier is activated carbon C, the active component is Mn-doped BiOCl, the molar ratio of manganese element to bismuth element is 0.001:1, and the mass of the activated carbon C is 10wt% of the total mass of BiOCl and C.

[0081] The difference between the preparation method of the above-mentioned Mn-doped BiOCl / C composite catalyst and that of Example 3 is that SBA-15 is replaced by activated carbon C.

[0082] Comparative Example 5

[0083] A Mn-doped BiOCl / gC 3 N 4 Composite catalyst, including carrier and active component, the carrier is gC 3 N 4 The active component is Mn-doped BiOCl, and the molar ratio of manganese to bismuth is 0.001:1; gC 3 N 4 The mass of BiOCl and gC 3 N 4 5wt% of the total mass.

[0084] The above Mn-doped BiOCl / gC 3 N 4 The difference between the preparation method of the composite catalyst and that of Example 2 is that SBA-15 is replaced by gC 3 N 4 . Among them, gC 3 N 4 The method comprises the steps of placing melamine in a crucible with a lid and calcining the crucible at 550°C for 5 h in a muffle furnace.

[0085] Results

[0086] The catalysts prepared in Examples 1 to 7 and Comparative Examples 1 to 5 were subjected to structural characterization and performance testing, respectively.

[0087] (1) XRD test

[0088] The crystal structures of Example 1, Comparative Example 1 and Comparative Example 2 were analyzed by XRD. Figure 1 The results show that all synthesized samples match the tetragonal BiOCl (PDF#85-0861) of the P4 / nmm (129) space group, proving the existence of BiOCl crystals. No obvious SBA-15 diffraction peaks were detected in Example 1 and Comparative Example 2, which is due to the SiO 2 Due to low crystallinity. Since the Mn doping in Example 1 is low, no corresponding XRD peak is found.

[0089] (2) Raman test

[0090] Figure 2The Raman test results of the catalysts of Example 1, Comparative Example 1 and Comparative Example 2 are shown. The test results show that the peak intensities are ranked from strong to weak in Comparative Example 1 (BOC), Example 1 (Mn / BOC / SBA-15) and Comparative Example 2 (BOC / SBA-15). It can be observed from the figure that the peak at 60 cm -1 and 146 cm -1 The peak at 202 cm -1 The peak at 399 cm -1 A weaker peak was observed at , representing the motion of oxygen atoms in the Bi-O bond, belonging to the vibration of the B1g and Eg modes. It is worth noting that when BiOCl is loaded onto the SBA-15 support, the intensity of the Bi-Cl and Bi-O related vibration peaks is significantly weakened. This phenomenon suggests that the loading effect of SBA-15 may lead to a weakening of the bonding strength of the Bi-Cl and Bi-O bonds. Figure 3 (a) is the EPR graph of Example 1 before and after irradiation with VUV light. Figure 3 (b) is a comparison of theoretical simulation and experimental data of the EPR graph of Example 1 before and after irradiation under VUV light, indicating that oxygen vacancy signals were detected. This indicates that the weakening of the bonding strength of BiOCl by SBA-15 loading promotes the generation of surface active sites such as oxygen vacancies and chlorine vacancies under ultraviolet light irradiation, thereby enhancing the performance of the catalyst in the photocatalytic reaction.

[0091] (3) BET test

[0092] The present invention performs BET test on SBA-15 carrier, Example 1, Comparative Example 1 and Comparative Example 2, and the corresponding adsorption-desorption curves and specific surface areas are shown in FIG. Figure 4 As shown. The results show that the SBA-15 carrier itself has a high specific surface area of ​​924 m² / g, while the specific surface area of ​​BiOCl in Comparative Example 1 is only 4.09 m² / g. By loading BiOCl on the surface of the SBA-15 carrier, the specific surface area of ​​the catalyst is significantly increased, wherein the specific surface areas of Example 1 and Comparative Example 2 are increased to 79.9 m² / g and 90.7 m² / g, respectively. The above results show that loading BiOCl on the SBA-15 carrier with a high specific surface area significantly improves the surface structure of the catalyst, especially in terms of specific surface area, thereby enhancing its adsorption performance. This phenomenon provides more active sites for the catalyst during the reaction process, thereby possibly improving its performance in the catalytic reaction.

[0093] (4) SEM and EDX testing

[0094] The morphological characteristics of the materials of Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 3 were investigated by SEM. Figure 5 shown. Figure 5 (a) is the SEM image of the SBA-15 carrier of Comparative Example 3. Figure 5 (b) is the SEM image of Comparative Example 1. Figure 5 (c) is the SEM image of Comparative Example 2. Figure 5 (d) is the SEM image of Example 1. Among them, the SBA-15 of Comparative Example 3 is a porous strip structure, and the BiOCl of Comparative Example 1 is a micron-scale sheet structure. After BiOCl is loaded onto SBA-15, different from the sheet morphology of BiOCl, Example 1 and Comparative Example 2 present a block structure with rich surface wrinkles. This is because BiOCl 3+ and Cl - This is due to the Si-OH anchoring in the SBA-15 pores, which then crystallizes into BiOCl particles inside.

[0095] The EDX spectrum was used to analyze the BiOCl, SiO 2 The distribution of MnOx and BiOCl particles was found to be crystallized and expanded in the pores and gaps of SBA-15, resulting in the BiOCl surface being covered by a large amount of mesoporous SiO 2 Surrounding, MnOx is evenly dispersed on the surface and pores of SBA-15, and the proportion of Mn atoms on the catalyst surface is 0.12%.

[0096] The atomic fractions of different elements in Example 1 are shown in Table 1 below.

[0097] Table 1

[0098]

[0099] (5) VUV catalytic degradation of continuous flow VOCs waste gas test

[0100] Specific test method: The total flow rate of VOCs in the continuous flow system is controlled at 1 L / min, the concentration of VOCs is 20ppm, the relative humidity is 50%, and the reaction temperature is maintained at room temperature 25°C. The addition amount of each embodiment and comparative example is 0.1g. The experiment uses a flat-plate continuous flow reactor, with air inlet and outlet on one side. The residence time of the gas in the quartz tube and the catalytic reaction module is 1s and 5s respectively. Figure 6 Diagram of the reaction device for catalytic oxidation of continuous flow VOCs waste gas in the VUV system.

[0101] VUV lamp, emitting UV light at 185 nm and 254 nm.

[0102] Toluene degradation efficiency, COx selectivity and O 3The removal efficiency is calculated using Formula 1-3.

[0103] Formula 1

[0104] Formula 2

[0105] Formula 3

[0106] Where: ——VOCs concentration of reaction inlet gas (ppm);

[0107] ——VOCs concentration of reaction outlet gas (ppm);

[0108] ——CO of the reaction inlet gas 2 The sum of concentration and CO concentration (ppm);

[0109] ——CO in the reaction outlet gas 2 The sum of concentration and CO concentration (ppm);

[0110] A——the number of C atoms in a single VOCs molecule;

[0111] ——O produced by VUV lamp under VOCs-free reaction conditions 3 Concentration (ppm);

[0112] ——O in the outlet gas after reaction 3 Concentration (ppm).

[0113] The specific test results of toluene degradation are shown in Table 2 below.

[0114] Table 2

[0115]

[0116] The specific test results of chlorobenzene degradation are shown in Table 3 below.

[0117] Table 3

[0118]

[0119] According to the data in Table 1, the composite catalyst of the embodiment of the present invention exhibits better catalytic performance than the comparative example, and the toluene removal rate, COx selectivity and O 3 The removal rates of toluene and COx were improved. When degrading toluene, the removal rate of toluene could reach 62-76%, the selectivity of COx could reach 79-92%, and the removal rate of O 3The removal rate can reach 67~77%. When degrading chlorobenzene, the removal rate of chlorobenzene can reach 83%, and the COx selectivity can reach 100%. 3 The removal rate can reach 70%. This shows that the introduction of the high specific surface area SBA-15 carrier effectively improves the surface properties of BiOCl, significantly increases the specific surface area of ​​the catalyst, thereby enhancing its adsorption capacity for VOCs and providing more surface active sites for the catalytic reaction. Therefore, the SBA-15-loaded BiOCl catalyst exhibits more superior mineralization degradation performance in the VUV photocatalytic degradation of toluene and chlorobenzene.

[0120] By comparing the data of Example 1 and Comparative Example 2, it can be observed that after doping with Mn, O 3 The removal rate of O was significantly improved. This phenomenon shows that after doping with Mn, the catalyst 3 The decomposition and activation ability of the catalyst were significantly improved. This may be attributed to the effective capture of Mn ions through the internal pores of SBA-15 and the Si-OH groups on its surface, which successfully achieved the loading of Mn and promoted the catalyst to 3 Catalytic effect during decomposition.

[0121] It can be seen from Tables 1 and 2 that the Mn / BOC / SBA-15 catalysts of the embodiments all exhibit excellent degradation and mineralization effects on aromatic hydrocarbon VOCs in the atmosphere.

[0122] It can be seen from the embodiment and comparative examples 4 and 5 that the present invention uses SBA-15 as a carrier, and compared with other carriers, it exhibits more superior mineralization degradation performance in the VUV photocatalytic degradation of toluene and chlorobenzene.

[0123] It can be seen from Examples 1 to 4 that the mass of SBA-15 is 20 wt% to 30 wt% of the total mass of BiOCl and SBA-15, which has a better 3 removal rate and has high COx selectivity.

[0124] It can be seen from Examples 1 and 5 to 7 that the molar ratio of manganese element to bismuth element is (0.001 to 0.003): 1, which has a better toluene degradation efficiency and O 3 removal rate.

[0125] (6) The environmental adaptability and stability of the Mn / BOC / SBA-15 catalyst in Example 1 for degradation of composite VOCs (10 ppm toluene + 10 ppm chlorobenzene) were evaluated. The test results are as follows: Figure 7As shown. When the humidity was 20-90%, in the five cycles of tests carried out at different humidity levels, the catalyst showed no obvious deactivation phenomenon, and the TVOC removal efficiency was always stable at about 90%. These results show that the Mn / BOC / SBA-15 catalyst has good adaptability and universality in the degradation process of VOCs, indicating the application potential of the catalyst in actual industrial waste gas treatment.

[0126] Obviously, the above embodiments of the present invention are only examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. Application of a Mn-doped BiOCl / SBA-15 composite catalyst in catalytic oxidation of continuous flow VOCs waste gas in a VUV system, characterized in that: The Mn-doped BiOCl / SBA-15 composite catalyst comprises a carrier and an active component, wherein the carrier is SBA-15, the active component is Mn-doped BiOCl, the molar ratio of manganese element to bismuth element (0.001-0.002): 1; the mass of SBA-15 is 20wt%-30wt% of the total mass of BiOCl and SBA-15; The preparation method of the Mn-doped BiOCl / SBA-15 composite catalyst comprises the following steps: S1. SBA-15 carrier, bismuth salt and chlorine source were added to glacial acetic acid to obtain BiOCl / SBA-15 composite catalyst by hydrothermal reaction; S2. The BiOCl / SBA-15 composite catalyst obtained in step S1 and a soluble manganese salt are mixed and stirred in ethanol, and dried to obtain a Mn-doped BiOCl / SBA-15 composite catalyst.

2. The use according to claim 1, characterized in that The specific surface area of ​​the Mn-doped BiOCl / SBA-15 composite catalyst is 70-100 m 2 / g.

3. The use according to claim 1, characterized in that The specific surface area of ​​the SBA-15 carrier is 800-1200 m 2 / g.

4. The use according to claim 1, characterized in that In step S1, the temperature of the hydrothermal reaction is 160-180° C., and the time of the hydrothermal reaction is 20-24 hours.

5. The use according to claim 1, characterized in that The soluble manganese salt is one of manganese acetate tetrahydrate and manganese sulfate.

6. The use according to claim 1, characterized in that The VOCs are one or more of toluene and chlorobenzene.

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