A preparation method of a supported catalyst for removing styrene, and products and applications thereof
By preparing a hierarchical porous molecular sieve support and loading it with active metals, and optimizing the impregnation liquid volume and metal loading, the problem of insufficient low-temperature catalytic activity in the existing catalytic combustion method was solved, achieving a lower T90 temperature and higher catalytic efficiency.
Patent Information
- Application Number
- CN202311248890.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-09-26
- Publication Date
- 2025-12-09
- Estimated Expiration
- 2043-09-26
AI Technical Summary
In existing catalytic combustion technologies for styrene removal, low-temperature catalytic activity remains high, and the T90 temperature is too high to be further reduced.
A method for preparing supported catalysts is employed, in which a hierarchical porous molecular sieve support is prepared through specific process steps, and metals such as palladium, copper, and silver are used as active components. The impregnation liquid volume and metal loading are optimized to prepare a catalyst with a larger specific surface area and more mesopores and micropores.
It significantly improved catalytic activity, reduced the T90 temperature of styrene to 135℃, and improved the low-temperature removal efficiency of catalytic combustion.
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Figure CN117101735B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of catalysts, in particular to a preparation method of a supported catalyst for removing styrene, and products and applications thereof. BACKGROUND
[0002] Styrene, as an indispensable important monomer in synthetic rubber and resin, is easy to polymerize and oxidize in the air, and is colorless and transparent with toxicity, which has paralyzing and stimulating effects on the human body. Even if it is long-term contact chronic poisoning, it will also cause blood diseases and carcinogenic symptoms in the human body.
[0003] Currently, the main removal technologies for styrene are plasma purification technology, photocatalytic technology, electrochemical technology, activated carbon adsorption technology and catalytic combustion technology. Catalytic combustion technology has the characteristics of low conversion temperature and not easy to produce secondary pollution, and is one of the most effective methods for controlling VOCs emission at present. The catalysts used in catalytic combustion technology can be roughly divided into the following three categories: noble metals, transition metals and their oxides, and composite metal oxide catalysts. Due to its special electronic structure, noble metal catalysts are easy to adsorb organic matter for catalytic reaction, and the catalyst strength is moderate, which is easy to form intermediates, so the catalytic activity is high, resistant to high temperature and oxidation. Noble metals are usually supported on the surface of the carrier, and have strong interaction with the carrier, which makes the active components highly dispersed and increases the active sites of the catalytic reaction. At the same time, the carrier not only plays a supporting structure and dispersing active component role, but also has a carrier effect, which makes the catalytic effect more obvious. For example, Xiaogang (Xiaogang, Modified perovskite catalyst for catalytic combustion of styrene [D]. Central China University of Science and Technology, 2019.) doped Cu on the perovskite catalyst to modify the catalyst, and when the doping amount was 0.4, the conversion rate of the catalyst for catalytic oxidation of styrene was the highest, T 90 = 308℃; Song Shengnan (Song Shengnan, Preparation of high-efficiency Pd-loaded molecular sieve catalyst and its application in catalytic combustion of VOCs [D]. Guangdong University of Technology, 2021.) doped Pd on Ti-doped SBA-15 to catalyze the combustion of styrene, T 90 = 210℃; Sun Qiming, Xiao Li, Zhao Chaocheng, et al. Preparation of titanium-based catalyst and its catalytic oxidation performance of styrene [J]. Journal of Environmental Engineering, 2015, 9(07): 3387-3392. TiO2 as a carrier doped with MnO x and then added the additive cerium oxide to catalyze the combustion of styrene, and when Ce / Ti = 0.05, T 90 = 199℃.
[0004] It can be seen that with the continuous improvement of the performance of the catalyst, the low-temperature catalytic activity has been improved, but T 90 is still relatively high. SUMMARY
[0005] In view of the above problems existing in the prior art, the application discloses a preparation method of a supported catalyst for removing styrene. 90 The temperature is lowered to 135 DEG C.
[0006] The specific technical solutions are as follows:
[0007] The application discloses a preparation method of a supported catalyst for removing styrene.
[0008] (1) a silica source, an aluminum source, a template agent, a directing agent and water are mixed under heating to obtain a colloidal solution, and the colloidal solution is aged, dried and then a dry gel is obtained;
[0009] (2) the dry gel is loaded into a crucible, and then is loaded into an inner liner of a crystallization kettle, water is added between the inner liner and the crucible and is not immersed above the upper edge of the crucible, and the water is heated and crystallized, and finally the multi-level pore molecular sieve carrier is obtained through washing, drying and calcination;
[0010] (3) the multi-level pore molecular sieve carrier is added into an impregnation solution for impregnation, drying and calcination, and the supported catalyst is prepared;
[0011] The impregnation solution is selected from an aqueous solution of a soluble salt of a metal.
[0012] The volume of the impregnation solution is greater than the volume of the multi-level pore molecular sieve carrier.
[0013] The application discloses a preparation method of a supported catalyst, and a multi-level pore molecular sieve carrier with a larger specific surface area and more mesopores and micropores is prepared through a special process.
[0014] Through experiments, it is found that if the dry gel is directly added into the inner liner of the crystallization kettle for heating and crystallization in step (2), the supported catalyst prepared through the method cannot obtain better catalytic activity when removing styrene through a catalytic combustion method.
[0015] Through experiments, it is also found that if the same volume impregnation is adopted when loading the metal in step (3), that is, the volume of the multi-level pore molecular sieve carrier added is equal to the volume of the impregnation solution added, the supported catalyst prepared through the method cannot obtain better catalytic activity when removing styrene through the catalytic combustion method.
[0016] In step (1):
[0017] The silica source is selected from one or more of tetraethyl orthosilicate, silane, silicon dioxide and sodium silicate.
[0018] the aluminum source is selected from one or more of aluminum isopropoxide, aluminum oxide, aluminum sulfate;
[0019] the template agent is selected from one or more of F127, CTAB, ethylenediamine, n-butylamine;
[0020] the directing agent is selected from one or more of tetrapropylammonium hydroxide, tetrapropylammonium bromide, molecular sieve seed;
[0021] Preferably:
[0022] the molar ratio of the silicon source to the aluminum source is 1:(0.01-1);
[0023] the molar ratio of the silicon source, the template agent, and the directing agent is 1:(0.001-0.1):(0.1-1);
[0024] the concentration of the silicon source in the colloidal solution is 1-10 mol / L.
[0025] Further preferably:
[0026] the molar ratio of the silicon source to the aluminum source is 1:(0.01-0.1);
[0027] the molar ratio of the silicon source, the template agent, and the directing agent is 1:(0.001-0.01):(0.1-1);
[0028] the concentration of the silicon source in the colloidal solution is 1-5 mol / L.
[0029] Preferably:
[0030] heating to 30-80℃;
[0031] the aging is at a temperature of 40-100℃ for 1-10 h.
[0032] in step (2):
[0033] the crystallization treatment is at a temperature of 100-200℃ for 12-24 h;
[0034] the calcination treatment is at a temperature of 400-600℃ for 10-15 h.
[0035] in step (3):
[0036] the soluble salt of the metal is selected from one or more of a nitrate, a sulfate, and a chloride of the metal;
[0037] the metal is selected from one or more of palladium, copper, silver, iron, cobalt, and tin;
[0038] The water-soluble salt of the metal has a concentration of 10-100 mmol / L, preferably 10-50 mmol / L.
[0039] Preferably, the volume of the impregnation solution is 5-10 times the volume of the hierarchical porous molecular sieve carrier.
[0040] In step (3), the temperature of the calcination treatment is 400-600℃.
[0041] In step (3), the temperature of the calcination treatment is 400-600℃.
[0042] The application also discloses a supported catalyst prepared according to the method.
[0043] The application also discloses the application of the supported catalyst in removing styrene, wherein the metal in the supported catalyst is selected from one or more of palladium, copper and silver, and the metal loading is 0.5-2.0 wt%.
[0044] Preferably, the metal in the supported catalyst is selected from palladium and / or silver, and the metal loading is 1.0-2.0 wt%.
[0045] When the preferred supported catalyst is used to remove styrene, the T 90 .
[0046] Compared with the prior art, the application has the following beneficial effects:
[0047] The application discloses a preparation method of a supported catalyst for removing styrene. 90 The application also discloses a preparation method of a supported catalyst for removing styrene. BRIEF DESCRIPTION OF DRAWINGS
[0048] Figure 1 BET curves of the supported catalysts prepared in Example 1 and Comparative Example 1, respectively;
[0049] Figure 2 XRD curves of the supported catalysts prepared in Example 1 and Comparative Example 1, respectively;
[0050] Figure 3 The curves of styrene conversion rate changing with temperature when the supported catalysts prepared in Example 1, Comparative Examples 1-3, respectively, are used to remove styrene;
[0051] Figure 4 The curves of styrene conversion rate changing with temperature when the supported catalysts prepared in Example 1-3, respectively, are used to remove styrene;
[0052] Figure 5The conversion of styrene versus temperature curves for the supported catalysts prepared for Examples 1, 4-5 when used to remove styrene. DETAILED DESCRIPTION
[0053] In order to make the objects, features and advantages of the present application more obvious, the following examples are further listed to explain the present application in detail. The following examples are only used to further explain the present application, and cannot be understood as a limitation to the protection scope of the present application, and some non-essential improvements and adjustments made by the person skilled in the art according to the principles set forth in the present application all belong to the protection scope of the present application.
[0054] Example 1
[0055] Preparation of the support: 3.2 g of F127 (polyoxyethylene polyoxypropylene ether block copolymer), 10.4 g of tetraethyl orthosilicate, 0.255 g of aluminum isopropoxide and 4.1 g of tetrapropylammonium hydroxide were dissolved in 36 mL of deionized water in a 40°C water bath, and a colloidal solution was obtained after continuous stirring for 2 h. The colloidal solution was aged in an oven at 60°C for 8 h, and then dried in an oven at 90°C for 12 h; the dried xerogel obtained was loaded into a crucible, placed in a white inner liner of a crystallization kettle, and water was added between the inner liner and the crucible without submerging the upper edge of the crucible, and crystallized at 160°C for 18 h; finally, the product was washed with deionized water, suction filtered, dried for 10 h, and calcined at 600°C for 10 h to obtain a white powder of the hierarchical pore molecular sieve support.
[0056] Pd loading on the support: the prepared support was first calcined in a muffle furnace at 400°C for 4 h (if the support is freshly prepared, this step of calcination process is not required), then 2 g of the calcined support was placed in a 20 mmol / L aqueous solution of palladium nitrate (the volume of the aqueous solution of palladium nitrate was 7 times the volume of the support), and impregnation was performed, after which the sample was placed in an oven at 80°C for drying, and after drying was completed, the sample was calcined in a muffle furnace at 500°C for 4 h to obtain a hierarchical pore molecular sieve supported Pd catalyst, and the Pd loading was 1.0%.
[0057] The desorption test by N2 showed that the specific surface area, pore volume and pore size data of the hierarchical pore molecular sieve supported Pd catalyst prepared in this example and the supported catalyst prepared in Comparative Example 1 are listed in Table 1 below.
[0058] Table 1
[0059]
[0060]
[0061] Figure 1 The BET curve of the hierarchical pore molecular sieve supported Pd catalyst prepared in this example is shown in the figure, and the BET curve of the supported catalyst prepared in Comparative Example 1 is also given as a comparison. It can be observed that the hierarchical pore molecular sieve supported Pd catalyst prepared in this example has a larger specific surface area and pore volume than the supported catalyst prepared in Comparative Example 1. Figure 1It can be found that both of the catalysts have different pore volume in the range of 0-50 nm, which proves that both of the catalysts are of hierarchical pore structure; but the hierarchical pore molecular sieve supported Pd catalyst prepared in this example has more mesopores and micropores than the supported catalyst prepared in Comparative Example 1.
[0062] Figure 2 The XRD curve of the hierarchical pore molecular sieve supported Pd catalyst prepared in this example is given in the figure, and the XRD curve of the supported catalyst prepared in Comparative Example 1 is also given in the figure as a comparison. It can be observed that Figure 2 It can be found that there is no obvious PdO or Pd characteristic diffraction peak in both of the supported Pd catalysts, which indicates that the Pd on the support has a high dispersion degree.
[0063] Comparative Example 1
[0064] The support used in this example is a commercially available molecular sieve (ZSM-5), and the process of loading Pd on the support is exactly the same as that in Example 1.
[0065] Comparative Example 2
[0066] The preparation process is basically the same as that in Example 1, and the only difference is that the dry gel is directly put into the white lining of the crystallization kettle during the preparation of the support, and no water is added.
[0067] Comparative Example 3
[0068] The preparation process is basically the same as that in Example 1, and the only difference is that the volume of the impregnation solution (palladium nitrate aqueous solution) is the same as that of the support when the support is loaded with Pd, that is, equal volume impregnation is used.
[0069] Examples 2-3
[0070] The preparation process is basically the same as that in Example 1, and the only difference is that the Pd loading amount is replaced by 0.5wt% in Example 2 and by 2wt% in Example 3 when the support is loaded with Pd by adjusting the concentration of palladium nitrate.
[0071] Example 4
[0072] The preparation process is basically the same as that in Example 1, and the only difference is that the palladium nitrate aqueous solution is replaced by an aqueous solution of copper nitrate with the same concentration when the support is loaded with metal.
[0073] Example 5
[0074] The preparation process is basically the same as that in Example 1, and the only difference is that the palladium nitrate aqueous solution is replaced by an aqueous solution of silver nitrate with the same concentration when the support is loaded with metal.
[0075] Application test:
[0076] The supported catalysts prepared in each of the examples or comparative examples were used to remove styrene by catalytic combustion method, and the styrene conversion rate change curves with temperature under the action of different supported catalysts were studied.
[0077] The catalytic activities of the supported catalysts prepared in each of the examples and comparative examples are listed in Table 2 below.
[0078] Table 2
[0079] Number T 90 (°C) Conversion / % Example 1 146 90 Comparative Example 1 206 90 Comparative Example 2 178 90 Comparative Example 3 168 90 Example 2 215 90 Example 3 135 90 Example 4 237 90 Example 5 158 90
[0080] Figure 3 The curves of the catalytic oxidation reaction activities of different catalysts for styrene when the supported Pd catalysts prepared in Example 1 and Comparative Examples 1-3 were used to remove styrene by catalytic combustion method were observed. Figure 3 It can be found that the supported Pd catalyst prepared in Example 1 has significantly higher catalytic activity than the supported catalysts prepared in Comparative Examples 1-3 throughout the low-temperature reaction process, has a lower T 90 and more excellent catalytic activity.
[0081] Figure 4 The curves of the catalytic oxidation reaction activities of different catalysts for styrene when the supported Pd catalysts prepared in Examples 1-3 were used to remove styrene by catalytic combustion method were observed. Figure 4 It can be found that the supported catalysts prepared in Example 3, Example 1 and Example 2 have gradually decreasing catalytic activities, and therefore, the loading amount of metal in the supported catalyst prepared in the application is preferably 1.0-2.0 wt%, and more preferably 2.0 wt% when applied to the catalytic oxidation reaction of styrene.
[0082] Figure 5 The curves of the catalytic oxidation reaction activities of different catalysts for styrene when the supported Pd catalysts prepared in Examples 1, 4 and 5 were used to remove styrene by catalytic combustion method were observed. Figure 5 It can be found that the supported catalysts prepared in Example 1, Example 5 and Example 4 have gradually decreasing catalytic activities, and therefore, the type of loaded metal in the supported catalyst prepared in the application is preferably Pd or Ag, and more preferably Pd when applied to the catalytic oxidation reaction of styrene.
[0083] The preferred embodiments of the application are described in detail above, but the application is not limited thereto. Within the technical concept of the application, various simple modifications can be made to the technical solutions of the application, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as disclosed by the application and fall within the protection scope of the application.
Claims
1. Use of a supported catalyst for the removal of styrene, characterized in that, The metal in the supported catalyst is selected from palladium, and the metal loading is 1.0-2.0 wt%; the preparation method of the supported catalyst comprises the following steps: (1) mixing a silicon source, an aluminum source, a template agent, a directing agent and water under heating to obtain a colloidal solution, and obtaining a dry gel after aging and drying; (2) loading the dry gel into a crucible, placing the crucible into an inner liner of a crystallization kettle, adding water that does not submerge the upper edge of the crucible between the inner liner and the crucible, heating for crystallization treatment, and finally obtaining a hierarchical pore molecular sieve carrier after washing, drying and calcination treatment; (3) adding the hierarchical pore molecular sieve carrier into an impregnation solution for impregnation, drying and calcination treatment to prepare the supported catalyst; the impregnation solution is selected from an aqueous solution of a soluble salt of a metal; the metal is selected from palladium; the aqueous solution of the soluble salt of the metal has a concentration of 10-50 mmol / L; the volume of the impregnation solution is 5-10 times the volume of the hierarchical pore molecular sieve carrier.
2. Use of the supported catalyst according to claim 1 for the removal of styrene, characterized in that, In step (1): the silicon source is selected from one or more of tetraethyl orthosilicate, silane, silicon dioxide and sodium silicate; the aluminum source is selected from one or more of aluminum isopropoxide, aluminum oxide and aluminum sulfate; the template agent is selected from one or more of F127, CTAB, ethylenediamine and n-butylamine; the directing agent is selected from one or more of tetrapropylammonium hydroxide, tetrapropylammonium bromide and molecular sieve seeds.
3. Use of the supported catalyst according to claim 1 for the removal of styrene, characterized in that, In step (1): the molar ratio of the silicon source to the aluminum source is 1:(0.01-1); the molar ratio of the silicon source to the template agent to the directing agent is 1:(0.001-0.1):(0.1-1); the concentration of the silicon source in the colloidal solution is 1-10 mol / L.
4. Use of the supported catalyst according to claim 1 for the removal of styrene, characterized in that, In step (1): heating to 30-80°C; the aging is performed at a temperature of 40-100°C for 1-10 h.
5. Use of the supported catalyst according to claim 1 for the removal of styrene, characterized in that, In step (2): the crystallization treatment is performed at a temperature of 100-200°C for 12-24 h; the calcination treatment is performed at a temperature of 400-600°C for 10-15 h.
6. Use of the supported catalyst according to claim 1 for the removal of styrene, characterized in that, In step (3): the soluble salt of the metal is selected from one or more of a nitrate, a sulfate and a chloride of the metal.
7. Use of the supported catalyst according to claim 1 for the removal of styrene, characterized in that, In step (3): the calcination treatment is performed at a temperature of 400-600°C.
Citation Information
Patent Citations
Supported-type catalytic oxidation catalyst and preparation and application thereof
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