Bismuth molybdate type catalyst, preparation method and application thereof, and treatment method of organic wastewater
By preparing a bismuth molybdate catalyst with synergistic effects of α-Bi2Mo3O12 and γ-Bi2MoO6, the problems of low COD removal rate and secondary pollution of existing catalysts were solved, and efficient organic wastewater treatment was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA PETROLEUM & CHEMICAL CORP
- Filing Date
- 2024-11-27
- Publication Date
- 2026-05-29
Smart Images
Figure CN122098541A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of catalyst preparation technology, specifically relating to a bismuth molybdate catalyst, its preparation method and application, and a method for treating organic wastewater. Background Technology
[0002] Compared to many other wastewater treatment technologies, catalytic wet oxidation (CWAO) technology has a high efficiency in oxidizing and degrading high-concentration organic pollutants, and can completely solve the environmental problems of high-concentration wastewater from industries such as petrochemicals, pesticides, dyes, and food processing.
[0003] Based on the properties of the catalyst, catalytic wet oxidation technology is divided into homogeneous and heterogeneous catalytic wet oxidation. Early research focused on homogeneous technology. Although homogeneous catalysts have advantages such as high reaction efficiency and stable performance, they are soluble in wastewater and require separation later. Thorough separation is cumbersome, and incomplete separation can cause secondary pollution. Therefore, heterogeneous catalysts have become a research hotspot in recent years. Heterogeneous catalysts are mainly divided into two categories: noble metals and composite metal oxides. Among them, composite metal oxide catalysts mostly use Al2O3, SiO2, TiO2, ZrO2 or their composite oxides as supports, and the active components are mainly oxides of metal elements such as Mo, Bi, Fe, Cs, Co, Ni, and Mg. For example, CN101844827B discloses a catalyst for degrading high-concentration formaldehyde pollutants, which is composed of transition metal components (one of Cu, Ni, Fe, Mn, Co, and Zn) and rare earth elements supported on Al2O3, SiO2, or TiO2, and is prepared by impregnation method. CN101219376B discloses a catalyst for wastewater treatment, which uses γ-Al₂O₃ as a support, Mn oxide and Sn oxide as the main active components, and Sb oxide as a promoter. CN101485987B discloses a catalyst prepared by a layered impregnation method using powdered zinc-aluminum hydrotalcite as a support, Fe as the active component, and Ce and Ti as promoters. However, the COD removal rates of the above catalysts are not ideal when used to treat organic wastewater.
[0004] Therefore, it is of great significance to develop a catalyst with a high COD removal rate in the treatment of organic wastewater. Summary of the Invention
[0005] Based on the above analysis, the present invention aims to provide a bismuth molybdate catalyst, its preparation method and application, and a method for treating organic wastewater, in order to solve the technical problem of low chemical oxygen demand (COD) removal rate when treating organic wastewater in the prior art.
[0006] The objective of this invention is mainly achieved through the following technical solutions.
[0007] In a first aspect, the present invention provides a bismuth molybdate-type catalyst, comprising bismuth molybdate and a support; wherein the bismuth molybdate comprises α-Bi₂Mo₃O₃. 12 Two active crystalline phases, γ-Bi₂MoO₆ and α-Bi₂Mo₃O₆, are present. 12 The average particle size ratio is 0.01 to 0.045.
[0008] In this invention, bismuth molybdate is the main catalytically active phase of the bismuth molybdate-type catalyst. Specifically, α-Bi₂Mo₃O₃... 12 Belonging to the cation-vacant scheelite structure, it exhibits high activity for wet oxidation; while γ-Bi₂MoO₆ has cation vacancies on its surface and a layered bulk structure, lacking cation vacancies, thus its reactivity is relatively low, but its layered bulk structure is suitable for lattice oxygen transport. Therefore, α-Bi₂Mo₃O₆... 12 The two active crystalline phases, γ-Bi2MoO6 and γ-Bi2MoO6, exhibit a synergistic effect, with the synergistic effect being optimal when the ratio of their average particle size is 0.01 to 0.045.
[0009] The bismuth molybdate catalyst provided by this invention includes a support, which enables the catalyst to achieve a higher COD removal rate when used to treat organic wastewater.
[0010] According to some embodiments of the present invention, the mass ratio of bismuth molybdate to the support is (80-90):(10-20).
[0011] According to some embodiments of the present invention, the carrier comprises SiO2.
[0012] In this invention, the type of support affects the composition of the active crystalline phase of bismuth molybdate, with SiO2 support being preferred. Furthermore, introducing other active elements into the bismuth molybdate catalyst may also alter the composition of the active crystalline phase of bismuth molybdate.
[0013] In a second aspect, the present invention provides a method for preparing the bismuth molybdate catalyst described in the first aspect, comprising: mixing a solution including a molybdenum precursor and a bismuth precursor with a support precursor to obtain a slurry; spray drying the slurry to obtain a powder; mixing the powder, water and a binder, extruding, drying, and calcining to obtain the bismuth molybdate catalyst;
[0014] The mass ratio of the molybdenum precursor (calculated as MoO3) to the bismuth precursor (calculated as Bi2O3) is (74-78):(7-11).
[0015] According to some embodiments of the present invention, the sum of the masses of the molybdenum precursor (calculated as MoO3) and the bismuth precursor (calculated as Bi2O3) is in the mass ratio of the carrier precursor (calculated as carrier) to (80-90):(10-20).
[0016] According to some embodiments of the present invention, the carrier precursor comprises silica sol.
[0017] According to some embodiments of the present invention, the adhesive includes at least one of polyethylene glycol (PEG), carboxymethyl cellulose (CMC), and methyl cellulose.
[0018] According to some embodiments of the present invention, the amount of the binder added is less than 5% of the total mass of the catalyst, preferably 2 to 4%.
[0019] According to some embodiments of the present invention, the pulping temperature is 75-90°C and the pulping time is 1-2 hours.
[0020] According to some embodiments of the present invention, the spray drying temperature is 350–500°C, preferably 380–450°C.
[0021] According to some embodiments of the present invention, before the extrusion, the mixed material is dried at room temperature for 15 to 45 minutes.
[0022] According to some embodiments of the present invention, the drying temperature is 95-115°C and the drying time is 12-16 hours.
[0023] According to some embodiments of the present invention, the material is first dried at room temperature for 50 to 80 minutes before the drying process.
[0024] According to some embodiments of the present invention, the calcination temperature is 400-600°C, preferably 450-550°C; the calcination time is 2-4.5 h, preferably 2.5-4 h.
[0025] Thirdly, the present invention provides the application of the bismuth molybdate catalyst described in the first aspect or the bismuth molybdate catalyst prepared by the preparation method described in the second aspect in wet oxidation reactions, especially in the treatment of organic wastewater.
[0026] Fourthly, the present invention provides a method for treating organic wastewater, comprising: reacting organic wastewater with an oxidant in the presence of the bismuth molybdate catalyst described in the first aspect or the bismuth molybdate catalyst prepared by the preparation method described in the second aspect, thereby removing COD from the wastewater.
[0027] According to some embodiments of the present invention, the COD content of the organic wastewater is 20,000 to 40,000 ppm.
[0028] This invention does not explicitly limit the source of organic wastewater, such as polyether wastewater.
[0029] According to some embodiments of the present invention, the oxidant includes oxygen or air.
[0030] According to some embodiments of the present invention, the temperature of the contact reaction is 200–280°C, and the pressure of the contact reaction is 4–9 MPa.
[0031] Compared with the prior art, the present invention can achieve at least the following beneficial effects:
[0032] The bismuth molybdate catalyst provided by this invention is obtained through α-Bi₂Mo₃O₂ 12 The synergistic effect between the two active crystalline phases, γ-Bi2MoO6 and γ-Bi2MoO6, results in better catalytic activity, and has the advantage of high COD removal rate when used to treat organic wastewater. Attached Figure Description
[0033] Figure 1 The XRD patterns are of the catalysts in Example 2 and Comparative Example 1. Detailed Implementation
[0034] To make the technical problem to be solved, the technical solution, and the beneficial effects of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely for illustrating this patent and do not limit the scope of protection of this invention in any way.
[0035] Unless otherwise defined, the technical terms used in the following embodiments have the same meaning as commonly understood by those skilled in the art. Unless otherwise specified, the reagents used in the following embodiments are conventional biochemical reagents; the raw materials, instruments, and equipment used in the following embodiments can all be obtained commercially or by existing methods; unless otherwise specified, the reagent dosages are those used in routine experimental operations; unless otherwise specified, the experimental methods are conventional methods.
[0036] The testing methods for the performance data involved in the various embodiments and comparative examples of this invention are as follows:
[0037] (1) The type of active crystalline phase of the catalyst is shown by the XRD spectrum.
[0038] (2) The average particle size of the active crystalline phase of the catalyst is calculated using the Scherrer formula.
[0039] The Scherrer equation, D = Kλ / βcosθ, is the relationship between the average grain size and the half-maximum width at half maximum (WHM) of the diffraction peak. It is determined using an X-ray powder diffractometer. In the equation, D is the average size of the grain perpendicular to the crystal plane, K is the Scherrer constant, λ is the X-ray wavelength, β is the measured half-maximum width at half maximum (WHM) of the diffraction peak of the sample, and θ is the Bragg diffraction angle.
[0040] In the embodiments and comparative examples, "parts" refers to parts by weight.
[0041] Example 1
[0042] A solution of ammonium molybdate containing 78 parts of MoO3, a solution of bismuth nitrate containing 7 parts of Bi2O3, and a silica sol containing 15 parts of SiO2 were mixed to form a pulp. The pulping temperature was 80℃ and the pulping time was 2 hours.
[0043] The slurry was spray-dried (at a temperature of 400°C) to obtain powder.
[0044] The powder was placed in a kneader, and then 3 parts of methylcellulose (Chinese medicine) and 90 parts of water were added. The mixture was stirred and kneaded for 30 minutes. The agglomerated material was dried at room temperature for 20 minutes, then extruded and rolled into balls. The spherical material was first dried at room temperature for 60 minutes, then dried at 105℃ for 14 hours, and finally calcined at 480℃ for 3.2 hours to obtain a spherical catalyst with a diameter of 3 mm.
[0045] The catalyst composition is shown in Table 1.
[0046] Example 2
[0047] The catalyst was prepared according to Example 1, except that "ammonium molybdate solution containing 78 parts of MoO3 and bismuth nitrate solution containing 7 parts of Bi2O3" was replaced with "ammonium molybdate solution containing 77 parts of MoO3 and bismuth nitrate solution containing 8 parts of Bi2O3".
[0048] The catalyst composition is shown in Table 1.
[0049] Example 3
[0050] The catalyst was prepared according to Example 1, except that "ammonium molybdate solution containing 78 parts of MoO3 and bismuth nitrate solution containing 7 parts of Bi2O3" was replaced with "ammonium molybdate solution containing 76 parts of MoO3 and bismuth nitrate solution containing 9 parts of Bi2O3".
[0051] The catalyst composition is shown in Table 1.
[0052] Example 4
[0053] The catalyst was prepared according to Example 1, except that "ammonium molybdate solution containing 78 parts of MoO3 and bismuth nitrate solution containing 7 parts of Bi2O3" was replaced with "ammonium molybdate solution containing 75 parts of MoO3 and bismuth nitrate solution containing 10 parts of Bi2O3".
[0054] The catalyst composition is shown in Table 1.
[0055] Example 5
[0056] The catalyst was prepared according to Example 1, except that "ammonium molybdate solution containing 78 parts of MoO3 and bismuth nitrate solution containing 7 parts of Bi2O3" was replaced with "ammonium molybdate solution containing 74 parts of MoO3 and bismuth nitrate solution containing 11 parts of Bi2O3".
[0057] The catalyst composition is shown in Table 1.
[0058] Example 6
[0059] The catalyst was prepared according to Example 2, except that “silica sol containing 15 parts SiO2” was replaced with “Zr(NO3)4·5H2O containing 15 parts ZrO2”.
[0060] The catalyst composition is shown in Table 1.
[0061] Example 7
[0062] The catalyst was prepared according to Example 2, except that “silica sol containing 15 parts SiO2” was replaced with “Ce(NO3)3·6H2O containing 15 parts CeO2”.
[0063] The catalyst composition is shown in Table 1.
[0064] Comparative Example 1
[0065] The catalyst was prepared according to Example 1, except that "ammonium molybdate solution containing 78 parts of MoO3 and bismuth nitrate solution containing 7 parts of Bi2O3" was replaced with "ammonium molybdate solution containing 70 parts of MoO3 and bismuth nitrate solution containing 15 parts of Bi2O3".
[0066] The catalyst composition is shown in Table 1.
[0067] Comparative Example 2
[0068] The catalyst was prepared according to Example 1, except that "ammonium molybdate solution containing 78 parts of MoO3 and bismuth nitrate solution containing 7 parts of Bi2O3" was replaced with "ammonium molybdate solution containing 72 parts of MoO3 and bismuth nitrate solution containing 13 parts of Bi2O3".
[0069] The catalyst composition is shown in Table 1.
[0070] Comparative Example 3
[0071] The catalyst was prepared according to Example 1, except that "ammonium molybdate solution containing 78 parts of MoO3 and bismuth nitrate solution containing 7 parts of Bi2O3" was replaced with "ammonium molybdate solution containing 80 parts of MoO3 and bismuth nitrate solution containing 5 parts of Bi2O3".
[0072] The catalyst composition is shown in Table 1.
[0073] Comparative Example 4
[0074] The catalyst was prepared according to Example 1, except that "ammonium molybdate solution containing 78 parts of MoO3 and bismuth nitrate solution containing 7 parts of Bi2O3" was replaced with "ammonium molybdate solution containing 82 parts of MoO3 and bismuth nitrate solution containing 3 parts of Bi2O3".
[0075] The catalyst composition is shown in Table 1.
[0076] Comparative Example 5
[0077] The catalyst was prepared according to Example 1, except that "ammonium molybdate solution containing 78 parts of MoO3, bismuth nitrate solution containing 7 parts of Bi2O3 and silica sol containing 15 parts of SiO2" was replaced with "ammonium molybdate solution containing 90 parts of MoO3 and bismuth nitrate solution containing 10 parts of Bi2O3".
[0078] The catalyst composition is shown in Table 1.
[0079] Table 1
[0080]
[0081]
[0082] Performance testing
[0083] 100g of catalyst was loaded into a wet oxidation reactor (fixed-bed reactor, inner diameter 22mm, reactor length 700mm). Polyether wastewater (COD: 32000ppm) was mixed with oxygen and passed through the catalyst-loaded wet oxidation reactor. The reaction temperature was 270℃, the pressure was 6.5MPa, the oxygen to polyether wastewater volume ratio was 180, and the polyether wastewater mass hourly space velocity was 1.0 h⁻¹. -1 The COD value of the treated polyether wastewater was measured using a Hach analyzer, and the COD removal rate was calculated. The results are shown in Table 2.
[0084] Table 2
[0085]
[0086]
[0087] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.
Claims
1. A bismuth molybdate-type catalyst, characterized in that, Includes bismuth molybdate and a support; said bismuth molybdate comprises α-Bi₂Mo₃O 12 Two active crystalline phases, γ-Bi₂MoO₆ and α-Bi₂Mo₃O₆, are present. 12 The average particle size ratio is 0.01 to 0.
045.
2. The bismuth molybdate catalyst according to claim 1, characterized in that, The mass ratio of bismuth molybdate to the support is (80-90):(10-20).
3. The bismuth molybdate catalyst according to claim 1 or 2, characterized in that, The carrier includes SiO2.
4. The method for preparing the bismuth molybdate catalyst according to any one of claims 1-3, characterized in that, include: A solution containing molybdenum precursor and bismuth precursor is mixed with a carrier precursor to obtain a slurry; The slurry was spray-dried to obtain powder; the powder, water and binder were mixed, extruded, dried and calcined to obtain the bismuth molybdate catalyst. The mass ratio of the molybdenum precursor (calculated as MoO3) to the bismuth precursor (calculated as Bi2O3) is (74-78):(7-11).
5. The preparation method according to claim 4, characterized in that, The ratio of the sum of the masses of the molybdenum precursor (calculated as MoO3) and the bismuth precursor (calculated as Bi2O3) to the mass of the carrier precursor (calculated as carrier) is (80-90):(10-20). And / or, the carrier precursor includes silica sol.
6. The preparation method according to claim 4 or 5, characterized in that, The adhesive includes at least one of polyethylene glycol, carboxymethyl cellulose, and methyl cellulose; And / or, the amount of the binder added is less than 5% of the total mass of the catalyst, preferably 2 to 4%.
7. The preparation method according to any one of claims 4-6, characterized in that, The pulping temperature is 75–90°C; And / or, the spray drying temperature is 350–500°C; And / or, the drying temperature is 95–115°C; And / or, the calcination temperature is 400–600°C, and the calcination time is 2–4.5 h.
8. The application of the bismuth molybdate catalyst according to any one of claims 1-3 or the bismuth molybdate catalyst prepared by the preparation method according to any one of claims 4-7 in wet oxidation reactions, especially in the treatment of industrial organic wastewater.
9. A method for treating organic wastewater, characterized in that, include: In the presence of the bismuth molybdate catalyst according to any one of claims 1-3 or the bismuth molybdate catalyst prepared by the preparation method according to any one of claims 4-7, the organic wastewater is reacted with the oxidant.
10. The processing method according to claim 9, characterized in that, The oxidant includes oxygen or air; And / or, the temperature of the contact reaction is 200–280°C, and the pressure of the contact reaction is 4–9 MPa.