A wet oxidation catalyst, its preparation and use

Abstract

The application provides a wet oxidation catalyst and a preparation method and application thereof. The wet oxidation catalyst provided by the application comprises the following components in parts by weight: 15-35 parts of a carrier, 60-85 parts of a transition metal oxide and 0.5-8 parts of an alkali metal oxide, wherein the alkali metal oxide is selected from cesium oxide and / or rubidium oxide. When the wet oxidation catalyst of the application is used to treat formaldehyde-containing wastewater, the wet oxidation catalyst has the advantages of high degradation COD removal rate and long service life.

Description

Technical Field

[0001] This application belongs to the field of wastewater treatment, specifically relating to a wet oxidation catalyst, its preparation method, and its application. Background Technology

[0002] Chemical oxygen demand (COD) is the most significant pollutant in wastewater, with my country's annual discharge currently exceeding 20 million tons. Catalytic wet oxidation, as a high-end advanced oxidation technology, is primarily used to degrade COD. With my country's increasing emphasis on environmental protection, emission standards for water pollutants are becoming increasingly stringent, especially for COD. This places ever higher demands on the performance, particularly the lifespan, of catalytic wet oxidation catalysts.

[0003] Based on the properties of the catalyst, catalytic wet oxidation technology is divided into homogeneous and heterogeneous catalytic wet oxidation. Early research mainly focused on homogeneous catalysts, but this method was gradually phased out because the catalyst dissolving in wastewater caused secondary pollution, requiring subsequent treatment. In recent years, heterogeneous catalysts have become a research hotspot. Heterogeneous catalysts are mainly divided into two categories: noble metals and metal oxides. Among them, metal oxides mostly use Al2O3, SiO2, or their composite oxides as supports, and the active components are mostly composed of metal oxides of elements such as Fe, Mo, Mn, Cu, and Ni.

[0004] CN101219376B discloses a catalyst for wastewater treatment, which uses γ-Al₂O₃ as a support, Mn metal oxide, Sn metal oxide as the main active component, and Sb oxide as a promoter. CN101485987B belongs to the field of water treatment technology and environmental functional materials. This catalyst uses powdered zinc-aluminum hydrotalcite as a support, Fe as the active component, and Ce and Ti as promoters, and is prepared by a layered impregnation method. However, the above-mentioned wet oxidation catalysts all suffer from short lifespan in high-concentration formaldehyde wastewater. Summary of the Invention

[0005] To address the problems of the prior art, this application provides a wet oxidation catalyst, its preparation method, and its application.

[0006] In a first aspect, this application provides a wet oxidation catalyst, which, by weight, comprises the following components: 15-35 parts of support, 60-85 parts of transition metal oxide and 0.5-8 parts of alkali metal oxide, wherein the alkali metal oxide is selected from cesium oxide and / or rubidium oxide, and the transition metal oxide is selected from molybdenum oxide, manganese oxide and iron oxide.

[0007] In some embodiments, the weak acid content in the wet oxidation catalyst accounts for 30%-80% of the total acid content, for example, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, or any value between therewith. In some embodiments, the weak acid content in the wet oxidation catalyst accounts for 40%-70% of the total acid content.

[0008] In some embodiments, the weight parts of the support in the wet oxidation catalyst are 17, 19, 20, 21, 23, 25, 27, 29, 30, 31, 33 or any value between them.

[0009] In some embodiments, the weight parts of the transition metal oxide in the wet oxidation catalyst are 61, 63, 65, 67, 69, 70, 71, 73, 75, 77, 79, 80, 81, 83 or any value between them.

[0010] In some embodiments, the alkali metal oxide in the wet oxidation catalyst is 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, 5 parts, 5.5 parts, 6 parts, 6.5 parts, 7 parts, 7.5 parts or any value between them.

[0011] In some embodiments, the wet oxidation catalyst comprises 20-30 parts of support, 70-80 parts of transition metal oxide, and 1-5 parts of alkali metal oxide.

[0012] In some embodiments, the alkali metal oxide is selected from rubidium oxide and cesium oxide.

[0013] In some embodiments, the mass ratio of rubidium oxide to cesium oxide is (0.1-10):1, for example, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1.0:1, 1.5:1, 2.0:1, 2.5:1, 3.0:1, 3.5:1, 4.0:1, 4.5:1, 5.0:1, 5.5:1, 6.0:1, 6.5:1, 7.0:1, 7.5:1, 8.0:1, 8.5:1, 9.0:1, 9.5:1, or any value between them. In some embodiments, the mass ratio of rubidium oxide to cesium oxide is (0.5-0.8):1.

[0014] In some embodiments, the carrier is selected from silicon dioxide and / or aluminum oxide.

[0015] The alkali metals (Cs, Rb) in the wet oxidation catalyst of this application, combined with specific transition metal oxides, can effectively regulate the overall acidity of the catalyst, thereby giving the catalyst both high activity and high stability.

[0016] Secondly, this application provides a method for preparing the wet oxidation catalyst according to the first aspect, comprising:

[0017] S1: Mix the carrier source, the solution containing the transition metal source, and the solution containing the alkali metal source to prepare a slurry;

[0018] S2: Spray dry the slurry from step S1 to obtain a powdered product;

[0019] S3: The powdered product from step S2 is shaped, dried, and calcined to obtain the wet oxidation catalyst.

[0020] In some embodiments, the pulping temperature in step S1 is 60°C-90°C, for example, 65°C, 70°C, 75°C, 80°C, or 85°C. In some embodiments, the pulping temperature is 75°C-85°C.

[0021] In some embodiments, the pulping time in step S1 is 1-5 hours, for example 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, or 4.5 hours. In some embodiments, the pulping time is 1.5 hours to 3 hours.

[0022] In some embodiments, in step S2, the spray drying temperature is 300℃-500℃, for example, 330℃, 350℃, 370℃, 400℃, 430℃, 450℃, or 470℃. In some embodiments, the spray drying temperature is 300℃-400℃.

[0023] In some embodiments, the spray drying time in step S2 is 10 min to 90 min, for example, 20 min, 30 min, 40 min, 50 min, 60 min, 70 min, or 80 min. In some embodiments, the spray drying time is 30 min to 60 min.

[0024] In some embodiments, the drying temperature in step S3 is 90°C-120°C, for example, 95°C, 100°C, 105°C, 110°C, or 115°C. In some embodiments, the drying time is 10-24 hours, for example, 12 hours, 18 hours, or 20 hours.

[0025] In some embodiments, the calcination temperature in step S3 is 400℃-600℃, for example, 450℃, 500℃, or 550℃. In some embodiments, the calcination time is 1h-5h, for example, 2h, 3h, or 4h.

[0026] In some embodiments, step S3, the molding includes: mixing the powdered product from step S2 with water and adhesive in an adhesive bonding machine for bonding, and then extruding and / or ball-forming the bonded material.

[0027] In some embodiments, the binder is selected from one or more of PEG, CMC, methylcellulose, and starch.

[0028] In some embodiments, the carrier source is selected from aluminum sol and / or silica sol.

[0029] In some embodiments, the transition metal source is selected from soluble salts of transition metals. In some embodiments, the transition metal source is selected from nitrates of transition metals. In some embodiments, the transition metal source is selected from molybdenum nitrate, manganese nitrate, and ferric nitrate.

[0030] In some embodiments, the alkali metal source is selected from soluble salts of alkali metals. In some embodiments, the alkali metal source is selected from cesium nitrate and / or rubidium nitrate.

[0031] Thirdly, this application provides the application of a wet oxidation catalyst prepared according to the wet oxidation catalyst described in the first aspect or the preparation method described in the second aspect in the treatment of formaldehyde-containing wastewater.

[0032] In some embodiments, the formaldehyde content in the formaldehyde-containing wastewater is 2% (wt) to 12% (wt), for example, 3 wt%, 5 wt%, 7 wt%, 9 wt%, 10 wt%, or 11 wt%.

[0033] In some embodiments, the COD of the formaldehyde-containing wastewater is 20,000 ppm to 100,000 ppm.

[0034] Fourthly, this application provides a method for treating formaldehyde-containing wastewater, wherein the formaldehyde-containing wastewater is reacted with an oxidant in the presence of the wet oxidation catalyst described in the first aspect or the wet oxidation catalyst prepared by the preparation method described in the second aspect, thereby removing COD from the formaldehyde-containing wastewater.

[0035] In some embodiments, the oxidant is oxygen or air.

[0036] In some embodiments, the reaction temperature is 220°C-300°C, for example 240°C, 260°C or 280°C.

[0037] In some embodiments, the reaction pressure is 5.0 MPaG-10.0 MPaG, for example 6.0 MPaG, 7.0 MPaG, 8.0 MPaG or 9.0 MPaG.

[0038] Compared with the prior art, this application has the following advantages:

[0039] The wet oxidation catalyst of this application has the advantages of high COD removal rate and long life when treating formaldehyde-containing wastewater. Attached Figure Description

[0040] Figure 1 The NH3-TPD chemisorption-desorption curves of the catalysts in Examples 1, 2 and Comparative Example 1 are shown. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with embodiments and accompanying drawings. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of this disclosure. Such structures and technologies have also been described in numerous publications.

[0042] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0043] In the context of this application, including the following examples and comparative examples, the acidity of the oxide catalyst was determined using an Altamira AMI-3300 instrument with NH3-TPD chemisorption-desorption curves. Before testing, the sample was activated at 550°C for 1 hour, ammonia was adsorbed at 100°C for 20 minutes, and then desorbed and detected at 100°C-600°C. By analyzing the Gaussian peak distribution, the acidity corresponding to desorption temperatures above 400°C was considered the acidity of a strong acid, and the acidity corresponding to desorption temperatures below 200°C was considered the acidity of a weak acid.

[0044] Unless otherwise specified, the pressures mentioned in the following examples and comparative examples are gauge pressures, and % represents mass percentage.

[0045] The present application will be further described below with reference to the embodiments, but the embodiments do not limit the scope of protection of the present application.

[0046] Example 1

[0047] 1. Catalyst Preparation

[0048] Step S1: A slurry containing 24 parts by weight of an ammonium molybdate solution of MoO3, 24 parts by weight of an iron nitrate solution of Fe2O3, 24 parts by weight of a manganese nitrate solution of MnO2, 2 parts by weight of a cesium nitrate solution of Cs2O, and 2 parts by weight of a rubidium nitrate solution of Rb2O is prepared with 24 parts by weight of silica sol containing SiO2. The slurry preparation temperature is 80℃, and the preparation time is 2.0 h. The resulting powder is obtained by spray drying (drying temperature 350℃, spray drying time 40 min).

[0049] Step S2: Place the powder into a kneader and mix. Add 3 parts by weight of methylcellulose and 90 parts by weight of water, and knead for 30 minutes. After the agglomerated material is dried at room temperature for 20 minutes, it is extruded and rolled into balls.

[0050] Step S3: The spherical material was first dried at room temperature for 60 min, and then dried in an oven at 105℃ for 14 h. Subsequently, it was calcined in a muffle furnace at 500℃ for 3.0 h to obtain shaped spherical catalysts with a diameter of 3 mm.

[0051] 2. Catalyst Evaluation

[0052] 100g of catalyst was loaded into a wet oxidation fixed-bed reactor for reaction. The reaction temperature was 250℃, the pressure was 6.5MPa, the oxygen to industrial wastewater volume ratio was 180, and the industrial wastewater mass hourly space velocity was 1.0 h⁻¹. -1 The COD value of the reaction products was determined using a Hach analyzer. The industrial wastewater was formaldehyde wastewater (COD: 38,000 ppm), with a formaldehyde content of 3.5% (wt).

[0053] The composition of the active components and the acid content distribution of the catalyst are shown in Table 1, and the catalyst evaluation results are shown in Table 2.

[0054] Example 2

[0055] 1. Catalyst Preparation

[0056] Step S1: A slurry containing 24 parts by weight of an ammonium molybdate solution of MoO3, 34 parts by weight of an iron nitrate solution of Fe2O3, 24 parts by weight of a manganese nitrate solution of MnO2, and 4 parts by weight of a cesium nitrate solution of Cs2O was prepared by mixing with 24 parts by weight of silica sol containing SiO2. The slurry preparation temperature was 80℃, and the preparation time was 2.0 h. The slurry was then spray-dried (drying temperature was 350℃, and spray drying time was 40 min) to obtain a powder.

[0057] Step S2: Place the powder into a kneader and mix. Add 3 parts by weight of methylcellulose and 90 parts by weight of water, and knead for 30 minutes. After the agglomerated material is dried at room temperature for 20 minutes, it is extruded and rolled into balls.

[0058] Step S3: The spherical material was first dried at room temperature for 60 min, and then dried in an oven at 105℃ for 14 h. Subsequently, it was calcined in a muffle furnace at 500℃ for 3.0 h to obtain shaped spherical catalysts with a diameter of 3 mm.

[0059] 2. Catalyst Evaluation

[0060] 100g of catalyst was loaded into a wet oxidation fixed-bed reactor for reaction. The reaction temperature was 250℃, the pressure was 6.5MPa, the oxygen to industrial wastewater volume ratio was 180, and the industrial wastewater mass hourly space velocity was 1.0 h⁻¹. -1 The COD value of the reaction products was determined using a Hach analyzer. The industrial wastewater was formaldehyde wastewater (COD: 38,000 ppm).

[0061] The composition of the active components and the acid content distribution of the catalyst are shown in Table 1, and the catalyst evaluation results are shown in Table 2.

[0062] Example 3

[0063] 1. Catalyst Preparation

[0064] Step S1: A slurry containing 24 parts by weight of an ammonium molybdate solution of MoO3, 24 parts by weight of an iron nitrate solution of Fe2O3, 24 parts by weight of a manganese nitrate solution of MnO2, and 4 parts by weight of a rubidium nitrate solution of Rb2O was prepared with 24 parts by weight of silica sol containing SiO2. The slurry preparation temperature was 80℃, and the preparation time was 2.0 h. The slurry was then spray-dried (drying temperature was 350℃, and spray drying time was 40 min) to obtain a powder.

[0065] Step S2: Place the powder into a kneader and mix. Add 3 parts by weight of methylcellulose and 90 parts by weight of water, and knead for 30 minutes. After the agglomerated material is dried at room temperature for 20 minutes, it is extruded and rolled into balls.

[0066] Step S3: The spherical material was first dried at room temperature for 60 min, and then dried in an oven at 105℃ for 14 h. Subsequently, it was calcined in a muffle furnace at 500℃ for 3.0 h to obtain shaped spherical catalysts with a diameter of 3 mm.

[0067] 2. Catalyst Evaluation

[0068] 100g of catalyst was loaded into a wet oxidation fixed-bed reactor for reaction. The reaction temperature was 250℃, the pressure was 6.5MPa, the oxygen to industrial wastewater volume ratio was 180, and the industrial wastewater mass hourly space velocity was 1.0 h⁻¹. -1The COD value of the reaction products was determined using a Hach analyzer. The industrial wastewater was formaldehyde wastewater (COD: 38,000 ppm).

[0069] The composition of the active components and the acid content distribution of the catalyst are shown in Table 1, and the catalyst evaluation results are shown in Table 2.

[0070] Example 4

[0071] 1. Catalyst Preparation

[0072] Step S1: The only difference from Example 1 is the use of 0.5 parts by weight of Cs2O cesium nitrate solution and 3.5 parts by weight of Rb2O rubidium nitrate solution.

[0073] Steps S2-S3: Same as in Example 1.

[0074] 2. Catalyst Evaluation

[0075] Same as Example 1

[0076] The composition of the active components and the acid content distribution of the catalyst are shown in Table 1, and the catalyst evaluation results are shown in Table 2.

[0077] Example 5

[0078] 1. Catalyst Preparation

[0079] Step S1: The only difference from Example 1 is the use of 1 part by weight of cesium nitrate solution of Cs2O and 3 parts by weight of rubidium nitrate solution of Rb2O.

[0080] Steps S2-S3: Same as in Example 1.

[0081] 2. Catalyst Evaluation

[0082] Same as Example 1

[0083] The composition of the active components and the acid content distribution of the catalyst are shown in Table 1, and the catalyst evaluation results are shown in Table 2.

[0084] Example 6

[0085] 1. Catalyst Preparation

[0086] Step S1: The only difference from Example 1 is the use of 3 parts by weight of cesium nitrate solution of Cs2O and 1 part by weight of rubidium nitrate solution of Rb2O.

[0087] Steps S2-S3: Same as in Example 1.

[0088] 2. Catalyst Evaluation

[0089] Same as Example 1

[0090] The composition of the active components and the acid content distribution of the catalyst are shown in Table 1, and the catalyst evaluation results are shown in Table 2.

[0091] Example 7

[0092] 1. Catalyst Preparation

[0093] Step S1: The only difference from Example 1 is the use of 3.5 parts by weight of Cs2O cesium nitrate solution and 0.5 parts by weight of Rb2O rubidium nitrate solution.

[0094] Steps S2-S3: Same as in Example 1.

[0095] 2. Catalyst Evaluation

[0096] Same as Example 1

[0097] The composition of the active components and the acid content distribution of the catalyst are shown in Table 1, and the catalyst evaluation results are shown in Table 2.

[0098] Example 8

[0099] 1. Catalyst Preparation

[0100] Step S1: A slurry containing 24.8 parts by weight of an ammonium molybdate solution of MoO3, 24.8 parts by weight of an iron nitrate solution of Fe2O3, 24.8 parts by weight of a manganese nitrate solution of MnO2, 0.4 parts by weight of a cesium nitrate solution of Cs2O, and 0.4 parts by weight of a rubidium nitrate solution of Rb2O was prepared with 24.8 parts by weight of silica sol of SiO2. The slurry preparation temperature was 80℃, and the preparation time was 2.0 h. The resulting powder was obtained by spray drying (drying temperature 350℃, spray drying time 40 min).

[0101] Steps S2-S3: Same as in Example 1.

[0102] 2. Catalyst Evaluation

[0103] Same as Example 1

[0104] The composition of the active components and the acid content distribution of the catalyst are shown in Table 1, and the catalyst evaluation results are shown in Table 2.

[0105] Example 9

[0106] 1. Catalyst Preparation

[0107] Step S1: A slurry containing 24.3 parts by weight of an ammonium molybdate solution of MoO3, 24.3 parts by weight of an iron nitrate solution of Fe2O3, 24.3 parts by weight of a manganese nitrate solution of MnO2, 1.4 parts by weight of a cesium nitrate solution of Cs2O, and 1.4 parts by weight of a rubidium nitrate solution of Rb2O was prepared by mixing with 24.3 parts by weight of silica sol containing SiO2. The slurry preparation temperature was 80℃, and the preparation time was 2.0 h. The resulting powder was obtained by spray drying (drying temperature 350℃, spray drying time 40 min).

[0108] Steps S2-S3: Same as in Example 1.

[0109] 2. Catalyst Evaluation

[0110] Same as Example 1

[0111] The composition of the active components and the acid content distribution of the catalyst are shown in Table 1, and the catalyst evaluation results are shown in Table 2.

[0112] Example 10

[0113] 1. Catalyst Preparation

[0114] Step S1: A slurry containing 23.5 parts by weight of an ammonium molybdate solution of MoO3, 23.5 parts by weight of an iron nitrate solution of Fe2O3, 23.5 parts by weight of a manganese nitrate solution of MnO2, 3 parts by weight of a cesium nitrate solution of Cs2O, and 3 parts by weight of a rubidium nitrate solution of Rb2O was prepared with 23.5 parts by weight of silica sol. The slurry preparation temperature was 80℃, and the preparation time was 2.0 h. The resulting powder was obtained by spray drying (drying temperature 350℃, spray drying time 40 min).

[0115] Steps S2-S3: Same as in Example 1.

[0116] 2. Catalyst Evaluation

[0117] Same as Example 1

[0118] The composition of the active components and the acid content distribution of the catalyst are shown in Table 1, and the catalyst evaluation results are shown in Table 2.

[0119] Comparative Example 1

[0120] 1. Catalyst Preparation

[0121] Step S1: A slurry containing 25 parts by weight of an ammonium molybdate solution of MoO3, 25 parts by weight of an ferric nitrate solution of Fe2O3, and 25 parts by weight of a manganese nitrate solution of MnO2 is prepared by mixing with 25 parts by weight of silica sol containing SiO2. The slurry preparation temperature is 80℃, and the preparation time is 2.0 h. The slurry is then spray-dried (drying temperature is 350℃, spray drying time is 40 min) to obtain a powder.

[0122] Step S2: Place the powder into a kneader and mix. Add 3 parts by weight of methylcellulose and 90 parts by weight of water, and knead for 30 minutes. After the agglomerated material is dried at room temperature for 20 minutes, it is extruded and rolled into balls.

[0123] Step S3: The spherical material was first dried at room temperature for 60 min, and then dried in an oven at 105℃ for 14 h. Subsequently, it was calcined in a muffle furnace at 500℃ for 3.0 h to obtain shaped spherical catalysts with a diameter of 3 mm.

[0124] 2. Catalyst Evaluation

[0125] 100g of catalyst was loaded into a wet oxidation fixed-bed reactor for reaction. The reaction temperature was 250℃, the pressure was 6.5MPa, the oxygen to industrial wastewater volume ratio was 180, and the industrial wastewater mass hourly space velocity was 1.0 h⁻¹. -1 The COD value of the reaction products was determined using a Hach analyzer. The industrial wastewater was formaldehyde wastewater (COD: 38,000 ppm).

[0126] The composition of the active components and the acid content distribution of the catalyst are shown in Table 1, and the catalyst evaluation results are shown in Table 2.

[0127] Comparative Example 2

[0128] 1. Catalyst Preparation

[0129] Step S1: A slurry containing 24 parts by weight of an ammonium molybdate solution of MoO3, 24 parts by weight of an ferric nitrate solution of Fe2O3, 24 parts by weight of a manganese nitrate solution of MnO2, and 4 parts by weight of a potassium nitrate solution of K2O was prepared by mixing with 24 parts by weight of silica sol containing SiO2. The slurry preparation temperature was 80℃, and the preparation time was 2.0 h. The slurry was then spray-dried (drying temperature was 350℃, and spray drying time was 40 min) to obtain a powder.

[0130] Steps S2-S3: Same as in Example 1.

[0131] 2. Catalyst Evaluation

[0132] Same as Example 1

[0133] The composition of the active components and the acid content distribution of the catalyst are shown in Table 1, and the catalyst evaluation results are shown in Table 2.

[0134] Comparative Example 3

[0135] 1. Catalyst Preparation

[0136] Step S1: A slurry containing 24 parts by weight of an ammonium molybdate solution of MoO3, 24 parts by weight of an ferric nitrate solution of Fe2O3, 24 parts by weight of a manganese nitrate solution of MnO2, and 4 parts by weight of a sodium nitrate solution of Na2O is prepared by mixing with 24 parts by weight of silica sol containing SiO2. The slurry preparation temperature is 80℃, and the preparation time is 2.0 h. The mixture is then spray-dried (drying temperature is 350℃, spray drying time is 40 min) to obtain a powder.

[0137] Steps S2-S3: Same as in Example 1.

[0138] 2. Catalyst Evaluation

[0139] Same as Example 1

[0140] The composition of the active components and the acid content distribution of the catalyst are shown in Table 1, and the catalyst evaluation results are shown in Table 2.

[0141] Comparative Example 4

[0142] 1. Catalyst Preparation

[0143] Step S1: A slurry containing 24 parts by weight of an ammonium molybdate solution of MoO3, 24 parts by weight of a nickel nitrate solution of NiO, 24 parts by weight of a manganese nitrate solution of MnO2, 2 parts by weight of a cesium nitrate solution of Cs2O, and 2 parts by weight of a rubidium nitrate solution of Rb2O is prepared by mixing with 24 parts by weight of silica sol containing SiO2. The slurry preparation temperature is 80℃, and the preparation time is 2.0 h. The mixture is then spray-dried (drying temperature is 350℃, spray drying time is 40 min) to obtain a powder.

[0144] Steps S2-S3: Same as in Example 1.

[0145] 2. Catalyst Evaluation

[0146] Same as Example 1

[0147] The composition of the active components and the acid content distribution of the catalyst are shown in Table 1, and the catalyst evaluation results are shown in Table 2.

[0148] Comparative Example 5

[0149] 1. Catalyst Preparation

[0150] Step S1: The only difference from Example 1 is the use of an ammonium molybdate solution containing 36 parts by weight of MoO3, an iron nitrate solution containing 0 parts by weight of Fe2O3, and a manganese nitrate solution containing 36 parts by weight of MnO2.

[0151] Steps S2-S3: Same as in Example 1.

[0152] 2. Catalyst Evaluation

[0153] Same as Example 1

[0154] The composition of the active components and the acid content distribution of the catalyst are shown in Table 1, and the catalyst evaluation results are shown in Table 2.

[0155] Comparative Example 6

[0156] 1. Catalyst Preparation

[0157] Step S1: The only difference from Example 1 is the use of an ammonium molybdate solution containing 0 parts by weight of MoO3, an iron nitrate solution containing 36 parts by weight of Fe2O3, and a manganese nitrate solution containing 36 parts by weight of MnO2.

[0158] Steps S2-S3: Same as in Example 1.

[0159] 2. Catalyst Evaluation

[0160] Same as Example 1

[0161] The composition of the active components and the acid content distribution of the catalyst are shown in Table 1, and the catalyst evaluation results are shown in Table 2.

[0162] Comparative Example 7

[0163] 1. Catalyst Preparation

[0164] Step S1: The only difference from Example 1 is the use of an ammonium molybdate solution containing 36 parts by weight of MoO3, an iron nitrate solution containing 36 parts by weight of Fe2O3, and a manganese nitrate solution containing 0 parts by weight of MnO2.

[0165] Steps S2-S3: Same as in Example 1.

[0166] 2. Catalyst Evaluation

[0167] Same as Example 1

[0168] The composition of the active components and the acid content distribution of the catalyst are shown in Table 1, and the catalyst evaluation results are shown in Table 2.

[0169] Table 1

[0170]

[0171] Table 2

[0172]

[0173]

[0174] The preferred embodiments of this application have been described in detail above; however, this application is not limited thereto. Within the scope of the technical concept of this application, various simple modifications can be made to the technical solution of this application, including combining various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in this application and are all within the protection scope of this application.

Claims

1. A wet oxidation catalyst, comprising, by weight, the following components: 15-35 parts of support, 60-85 parts of transition metal oxide, and 0.5-8 parts of alkali metal oxide. in, The alkali metal oxide is selected from cesium oxide and / or rubidium oxide, and the transition metal oxide is selected from molybdenum oxide, manganese oxide, and iron oxide.

2. The wet oxidation catalyst according to claim 1, characterized in that, The weak acid content in the wet oxidation catalyst accounts for 30%-80% of the total acid content, preferably 40%-70%.

3. The wet oxidation catalyst according to claim 1 or 2, characterized in that, It comprises 20-30 parts of carrier, 70-80 parts of transition metal oxide and 1-5 parts of alkali metal oxide.

4. The wet oxidation catalyst according to any one of claims 1-3, characterized in that, The alkali metal oxide is selected from rubidium oxide and cesium oxide. Preferably, the mass ratio of rubidium oxide to cesium oxide is (0.1-10):1, more preferably (0.5-0.8):

1.

5. The wet oxidation catalyst according to any one of claims 1-4, characterized in that, The carrier is selected from silicon dioxide and / or aluminum oxide.

6. A method for preparing a wet oxidation catalyst according to any one of claims 1-5, comprising: S1: Mix the carrier source, the solution containing the transition metal source, and the solution containing the alkali metal source to prepare a slurry; S2: Spray dry the slurry from step S1 to obtain a powdered product; S3: The powdered product from step S2 is shaped, dried, and calcined to obtain the wet oxidation catalyst.

7. The preparation method according to claim 6, characterized in that, In step S1, the pulping temperature is 60℃-90℃, preferably 75℃-85℃, and the pulping time is 1h-5h, preferably 1.5h-3h; and / or In step S2, the spray drying temperature is 300℃-500℃, preferably 300℃-400℃, and the spray drying time is 10min-90min, preferably 30min-60min; and / or In step S3, the drying temperature is 90℃-120℃, and the drying time is 10-24 hours; and / or The calcination temperature is 400℃-600℃, and the calcination time is 1h-5h; and / or In step S3, the molding process includes: mixing the powdered product from step S2 with water and adhesive in an adhesive bonding machine for bonding, and then extruding and / or ball-forming the bonded material. Preferably, the binder is selected from one or more of PEG, CMC, methylcellulose and starch.

8. The preparation method according to claim 6 or 7, characterized in that, The carrier source is selected from aluminum sol and / or silica sol; and / or The transition metal source is selected from soluble salts of transition metals, preferably from nitrates of transition metals, and more preferably from manganese nitrate, ferric nitrate, and bismuth nitrate; and / or The alkali metal source is selected from soluble salts of alkali metals, preferably from cesium nitrate and / or rubidium nitrate.

9. The application of the wet oxidation catalyst according to any one of claims 1-5 or the wet oxidation catalyst prepared by the preparation method according to any one of claims 6-8 in the treatment of formaldehyde-containing wastewater; Preferably, the formaldehyde content in the formaldehyde-containing wastewater is 2wt%-12wt%. Preferably, the COD of the formaldehyde-containing wastewater is 20,000 ppm to 100,000 ppm.

10. A method for treating formaldehyde-containing wastewater, comprising reacting the formaldehyde-containing wastewater with an oxidant in the presence of a wet oxidation catalyst according to any one of claims 1-5 or a wet oxidation catalyst prepared by the preparation method according to any one of claims 6-8. Preferably, the formaldehyde content in the formaldehyde-containing wastewater is 2wt%-12wt%. Preferably, the COD of the formaldehyde-containing wastewater is 20,000 ppm to 100,000 ppm; Preferably, the oxidant is oxygen or air; Preferably, the reaction temperature is 220℃-300℃; Preferably, the reaction pressure is 5.0 MPaG-10.0 MPaG.

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