Preparation method and application of catalytic wet oxidation catalyst containing rare earth metal

Abstract

The invention discloses a preparation method and application of a catalytic wet oxidation catalyst containing rare earth metal, and belongs to the technical field of catalyst preparation and acrylic acid wastewater treatment. According to the present invention, with the method of self-propagating combustion after the metal precursor and the comburent are mixed, the high-stability porous high-entropy oxide as the catalyst carrier can be synthesized in one step, and the noble metal active component loaded heterogeneous catalyst can be further synthesized; the preparation method is simple, the yield is high, the thermal stability and chemical stability are good, the porous structure is rich, and meanwhile lattice distortion, structural defects and electronic effects caused by the unique high-entropy effect are achieved. When the catalyst prepared by the method provided by the invention is used for treating acrylic acid wastewater, the service life of the catalyst can be remarkably prolonged, and the degradation effect of organic matters in the wastewater is improved.

Description

Technical Field

[0001] The present application relates to a preparation method of a catalytic wet oxidation catalyst containing rare earth metals and application thereof, belonging to the technical field of catalyst preparation and acrylic acid wastewater treatment. Background Art

[0002] Catalytic wet oxidation (CWAO) technology is an effective method for treating high-concentration wastewater and sludge that is difficult to degrade. At present, the widely used CWAO catalysts are mainly divided into homogeneous catalysts (such as copper-based and iron-based compounds) and heterogeneous catalysts (such as precious metals and oxides). However, the main problem faced by traditional catalysts is the dissolution of active ingredients, which leads to the loss of active sites, thereby reducing catalytic performance and reuse life. The methods currently disclosed in patents to improve life and activity are mainly to add active additives, especially rare earth metals, or by adding a shell layer. For example, CN 105712461B discloses a catalyst with a core-shell structure, with activated carbon as the core and alumina containing precious metals and rare earth metals as the shell, which improves the stability and efficiency of catalytic wet oxidation treatment of acrylic acid wastewater.

[0003] High entropy oxide (HEO) exhibits excellent stability and catalytic activity under high temperature conditions due to its unique high entropy effect, lattice distortion and chemical and physical stability. Unlike traditional multiphase catalysts, HEO is more likely to form a stable solid solution structure, which can effectively improve the service life of the catalyst; at the same time, its diverse structural defects and electronic effects are conducive to promoting the catalytic effect. For example, the document "Performance of high temperature phase-stable highentropyoxide (MgCuMnCoFe)Ox in catalytic wet air oxidation of chloroquine phosphate" discloses a synthetic high temperature stable (MgCuMnCoFe)Ox high entropy metal oxide for catalytic oxidation and degradation of chloroquine phosphate, but the specific surface area prepared by the traditional roasting method is only 0.14m 2 / g, which is not conducive to the full utilization of the catalyst. Therefore, a new roasting method is needed. Summary of the invention

[0004] In order to solve the problem of poor catalyst stability and catalytic activity at high temperature in the prior art of catalytic wet oxidation catalyst preparation, this application proposes a technical solution of a catalytic wet oxidation catalyst containing rare earth metals, which uses high entropy oxides with their unique high entropy effect, lattice distortion and chemical and physical stability to show excellent stability and catalytic activity under high temperature conditions; in addition, rare earth metals that are beneficial to promoting catalytic wet oxidation activity are introduced while synthesizing high entropy metal oxides. It is used for catalytic wet oxidation treatment of acrylic acid wastewater, and the effect is better than that of traditional catalyst processes.

[0005] This application adopts the following technical solutions: According to the first aspect of the present application, a method for preparing a catalytic wet oxidation catalyst containing a rare earth metal is provided, comprising the following steps: S1, heating a solid mixture containing a metal precursor and a combustion-supporting material, and then calcining the heated solid mixture to obtain a catalyst carrier; The metal precursor is selected from metal salts of at least five elements selected from iron, cobalt, nickel, manganese, molybdenum, magnesium, chromium, copper, lanthanum, neodymium, cerium, and gadolinium, and the metal salts of at least five elements include at least one metal salt of lanthanum, neodymium, cerium, and gadolinium; S2, impregnating the catalyst support in an aqueous solution containing a noble metal salt, and then drying the impregnated catalyst support to obtain a catalyst precursor; S3, calcining the catalyst precursor II to obtain the rare earth metal-containing catalytic wet oxidation catalyst.

[0006] Optionally, in step S1, the combustion-supporting material is selected from at least one of citric acid, glycine, urea, and ethylene glycol.

[0007] Optionally, in step S1, the metal salt is selected from at least one of metal nitrates, acetates, chlorides and perchlorates.

[0008] Optionally, in step S1, the weight ratio of the metal precursor to the combustion aid is 1:4-6:1 based on the weight of the metal element in the metal precursor.

[0009] Optionally, in step S1, the heating conditions include: heating at 100°C to 600°C to induce self-propagating combustion of the solid mixture until completion.

[0010] In the present application, self-propagating combustion refers to a technology that utilizes the self-heating and self-conduction effects of the high heat of chemical reaction between reactants to synthesize materials. Once the reactants are ignited, they will automatically propagate to the unreacted area until the reaction is complete. It is a new method for preparing high-temperature materials of inorganic compounds.

[0011] Optionally, in step S1, the heating condition has a temperature of 150°C to 300°C.

[0012] Optionally, in step S1, the solid mixture containing the metal precursor and the combustion aid is obtained by mixing and grinding the raw materials containing the metal precursor and the combustion aid; or, the raw materials containing the metal precursor and the combustion aid are added into water and stirred to obtain a mixed liquid, and the mixed liquid is dried to obtain the solid mixture.

[0013] Optionally, the concentration of the metal precursor in the mixed solution is 5wt.%~30wt.%.

[0014] The present application mixes the metal precursor and the combustion support by grinding and mixing or adding the two into water and stirring to obtain a mixed liquid. The temperature of the drying step can be set within the heating temperature range described in step S1, and then the mixture is calcined at 200°C~600°C to induce self-propagating combustion of the solid mixture.

[0015] Optionally, in step S2, the noble metal salt is a metal salt of at least one element selected from ruthenium, rhodium, palladium, osmium, iridium and platinum.

[0016] Optionally, the noble metal salt is selected from at least one of nitrates, chlorides and sulfates of noble metals.

[0017] Optionally, in step S2, the loading concentration of the noble metal salt in the catalyst precursor is 0.1 wt.% to 5 wt.% in terms of weight percentage of the heavy metal element.

[0018] Optionally, the conditions of calcination I and calcination II independently include: calcination temperature of 200° C. to 600° C., and calcination time of 0.5 h to 12 h.

[0019] According to another aspect of the present application, there is provided a catalytic wet oxidation catalyst containing rare earth metals prepared by the above-mentioned preparation method, wherein the catalytic wet oxidation catalyst containing rare earth metals comprises a carrier and a noble metal supported on the carrier; The carrier includes a high entropy oxide carrier, and the high entropy oxide carrier contains an oxide of at least one element selected from the group consisting of lanthanum, neodymium, cerium, and gadolinium.

[0020] According to another aspect of the present application, there is also provided a use of a rare earth metal-containing catalytic wet oxidation catalyst prepared by the above preparation method in catalytic wet oxidation degradation of acrylic acid wastewater.

[0021] Optionally, the chemical oxygen demand (COD) of the acrylic acid wastewater is 5000-100000 mg / L.

[0022] Optionally, the conditions for catalytic wet oxidation of acrylic acid wastewater degradation include at least one of the following conditions: (1) The reaction temperature of catalytic wet oxidation degradation of acrylic acid wastewater is 220℃~260℃.

[0023] (2) The volumetric space velocity of acrylic acid wastewater is 0.5h -1 ~3h -1 .

[0024] (3) The reaction pressure of catalytic wet oxidation degradation of acrylic acid wastewater is 1.0MPa ~7.0MPa.

[0025] (4) The oxidant in the catalytic wet oxidation reaction of acrylic acid wastewater degradation is at least one of air, oxygen and H2O2.

[0026] Optionally, the amount of oxidant actually added in the catalytic wet oxidation reaction of acrylic acid wastewater degradation is 5% to 50% more than the amount of oxidant required for complete oxidation of acrylic acid in the wastewater.

[0027] The beneficial effects of this application include: The preparation method of the rare earth metal-containing catalytic wet oxidation catalyst provided in the present application can effectively reduce the acrylic acid content in industrial wastewater by adopting a technical solution of noble metal-loaded high entropy alloy oxide as a catalytic wet oxidation multiphase catalyst, and has achieved good technical results. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 2 is the XRD diagram of the catalyst samples in Examples 1 to 8.

[0029] Figure 2 The scanning electron microscope photographs and corresponding element spectrum of the catalyst prepared in Example 1. (a) is a scanning electron microscope photograph of the catalyst in Example 1, and (b) is the corresponding element spectrum of the catalyst in Example 1, with a scale of 10 μm. DETAILED DESCRIPTION

[0030] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0031] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0032] Unless otherwise specified, conventional methods were used for testing and instrument settings were those recommended by the manufacturer.

[0033] In the examples of the present application, Rigaku Ultima IV XRD was used to determine the crystal form of the catalyst; and a Shimadzu TOC-VCPH / ce TOC analyzer was used to characterize the total organic carbon content.

[0034] Example 1 Preparation of Catalytic Wet Oxidation Catalyst 1.1 Preparation of Catalyst Support Add 3.3 g of lanthanum nitrate, 0.58 g of cobalt nitrate, 0.5 g of manganese nitrate, 0.81 g of iron nitrate, 0.58 g of nickel nitrate, 0.48 g of copper nitrate and 0.58 g of citric acid into 20 g of water, stir to dissolve, dry at 120°C, and calcine the obtained solid at 250°C in air for 2 h to obtain a catalyst carrier.

[0035] 1.2 Preparation of catalyst 50g of the catalyst carrier was immersed in 20mL of an aqueous solution of 0.5% by volume ruthenium nitrate at room temperature for 24h, and then dried at 105°C for 10h to obtain a catalyst precursor. The catalyst precursor was calcined at 350°C in an air atmosphere for 4h to obtain a catalytic wet oxidation catalyst.

[0036] Catalytic wet oxidation process The catalytic wet oxidation catalyst obtained in step 1 is used in the CWAO continuous reaction device to treat the acrylic acid model wastewater with COD = 10000 mg / L, and the TOC removal rate can reach 85%. Among them, the continuous reaction conditions are: reaction temperature is 220℃, reaction pressure is 3MPa, and the volume space velocity of acrylic acid wastewater is 1h -1 The oxidant is oxygen, and the actual dosage is 10% more than the amount required for complete oxidation of acrylic acid in the wastewater.

[0037] Example 2 Preparation of Catalytic Wet Oxidation Catalyst 1.1 Preparation of Catalyst Support 2.5 g of cerium nitrate, 0.62 g of chromium nitrate, 0.58 g of manganese nitrate, 0.73 g of magnesium nitrate, 0.45 g of nickel nitrate, 0.48 g of copper nitrate and 0.58 g of ethylene glycol were added to 30 g of water, stirred to dissolve, dried at 105°C, and the obtained solid was calcined at 400°C in air for 4 hours to obtain a catalyst carrier.

[0038] 1.2 Preparation of catalyst 50g of the catalyst carrier was immersed in 20mL of an aqueous solution of 3% by volume platinum chloride at room temperature for 24h, and then dried at 105°C for 10h to obtain a catalyst precursor. The catalyst precursor was calcined at 350°C in an air atmosphere for 4h to obtain a catalytic wet oxidation catalyst.

[0039] Catalytic wet oxidation process The catalytic wet oxidation catalyst obtained in step 1 is used in a CWAO continuous reaction device to treat acrylic acid model wastewater with COD = 20000 mg / L, and the TOC removal rate can reach 85%. Among them, the continuous reaction conditions are: reaction temperature is 250℃, reaction pressure is 5MPa, and the volume space velocity of acrylic acid wastewater is 0.5h-1 The oxidants are oxygen and air, and the actual dosage is 5% more than the dosage required for complete oxidation of acrylic acid in the wastewater.

[0040] Example 3 Preparation of Catalytic Wet Oxidation Catalyst 1.1 Preparation of Catalyst Support 3.5 g of gadolinium nitrate, 0.55 g of copper nitrate, 0.4 g of manganese chloride, 0.68 g of magnesium chloride, 0.53 g of ferric chloride, 0.58 g of molybdenum nitrate and 0.65 g of glycine were added to 20 g of water, stirred to dissolve, dried at 120°C, and the obtained solid was calcined at 300°C in air for 5 hours to obtain a catalyst carrier.

[0041] 1.2 Preparation of catalyst 50g of the catalyst carrier was immersed in 20mL of an aqueous solution with a volume fraction of 2% rhodium chloride at room temperature for 24h, and then dried at 105°C for 10h to obtain a catalyst precursor. The catalyst precursor was calcined at 350°C in an air atmosphere for 4h to obtain a catalytic wet oxidation catalyst.

[0042] Catalytic wet oxidation process The catalytic wet oxidation catalyst obtained in step 1 is used in the CWAO continuous reaction device to treat the acrylic acid model wastewater with COD = 40000 mg / L, and the TOC removal rate can reach 90%. Among them, the continuous reaction conditions are: reaction temperature is 220℃, reaction pressure is 4MPa, and the volume space velocity of acrylic acid wastewater is 2h -1 The oxidants are oxygen and air, and the actual dosage is 15% more than the amount required for complete oxidation of acrylic acid in the wastewater.

[0043] Example 4 Preparation of Catalytic Wet Oxidation Catalyst 1.1 Preparation of Catalyst Support Add 2.8 g of lanthanum chloride, 0.58 g of magnesium perchlorate, 0.63 g of copper nitrate, 0.70 g of molybdenum nitrate, 0.55 g of ferric chloride and 0.58 g of urea into 30 g of water, stir to dissolve, dry at 120°C, and calcine the obtained solid at 350°C in air for 3 h to obtain a catalyst carrier.

[0044] 1.2 Preparation of catalyst 50g of the catalyst carrier was immersed in 20mL of an aqueous solution with a volume fraction of 5% palladium nitrate at room temperature for 24h, and then dried at 105°C for 10h to obtain a catalyst precursor. The catalyst precursor was calcined at 350°C in an air atmosphere for 4h to obtain a catalytic wet oxidation catalyst.

[0045] Catalytic wet oxidation process The catalytic wet oxidation catalyst obtained in step 1 is used in the CWAO continuous reaction device to treat the acrylic acid model wastewater with COD = 60000 mg / L, and the TOC removal rate can reach 90%. Among them, the continuous reaction conditions are: reaction temperature is 240℃, reaction pressure is 4MPa, and the volume space velocity of acrylic acid wastewater is 2.5h -1 The oxidants are oxygen and H2O2, and the actual dosage is 30% more than the amount required for complete oxidation of acrylic acid in the wastewater.

[0046] Example 5 Preparation of Catalytic Wet Oxidation Catalyst 1.1 Preparation of Catalyst Support 3.0 g of iridium nitrate, 0.46 g of ferric nitrate, 0.33 g of copper chloride, 0.52 g of nickel chloride, 0.35 g of manganese nitrate, 0.25 g of chromium nitrate and 0.55 g of citric acid were added to 30 g of water, stirred to dissolve, dried at 120°C, and the obtained solid was calcined at 200°C in air for 4 hours to obtain a catalyst carrier.

[0047] 1.2 Preparation of catalyst 50g of the catalyst carrier was immersed in 20mL of an aqueous solution with a volume fraction of 2% platinum nitrate at room temperature for 24h, and then dried at 105°C for 10h to obtain a catalyst precursor. The catalyst precursor was calcined at 350°C in an air atmosphere for 4h to obtain a catalytic wet oxidation catalyst.

[0048] Catalytic wet oxidation process The catalytic wet oxidation catalyst obtained in step 1 is used in the CWAO continuous reaction device to treat the acrylic acid model wastewater with COD = 80000 mg / L, and the TOC removal rate can reach 80%. Among them, the continuous reaction conditions are: reaction temperature is 220℃, reaction pressure is 4MPa, and the volume space velocity of acrylic acid wastewater is 1.0h -1 The oxidant is H2O2, and the actual dosage is 20% more than the amount required for complete oxidation of acrylic acid in the wastewater.

[0049] Example 6 Preparation of Catalytic Wet Oxidation Catalyst 1.1 Preparation of Catalyst Support Add 3.5 g of iridium chloride, 0.55 g of ferric nitrate, 0.31 g of copper chloride, 0.52 g of nickel chloride, 0.56 g of manganese nitrate, 0.25 g of chromium nitrate and 0.58 g of ethylene glycol into 25 g of water, stir to dissolve, dry at 105°C, and calcine the obtained solid at 230°C in air for 3 h to obtain a catalyst carrier.

[0050] 1.2 Preparation of catalyst 50g of the catalyst carrier was immersed in 20mL of a mixed aqueous solution of 2% palladium nitrate and 1% ruthenium chloride at room temperature for 24h, and then dried at 105°C for 10h to obtain a catalyst precursor. The catalyst precursor was calcined at 350°C in an air atmosphere for 4h to obtain a catalytic wet oxidation catalyst.

[0051] Catalytic wet oxidation process The catalytic wet oxidation catalyst obtained in step 1 is used in the CWAO continuous reaction device to treat the acrylic acid model wastewater with COD = 10000 mg / L, and the TOC removal rate can reach 95%. Among them, the continuous reaction conditions are: reaction temperature is 240℃, reaction pressure is 6.5MPa, and the volume space velocity of acrylic acid wastewater is 1.0h -1 The oxidant is oxygen, and the actual dosage is 30% more than the amount required for complete oxidation of acrylic acid in the wastewater.

[0052] Example 7 Preparation of Catalytic Wet Oxidation Catalyst 1.1 Preparation of Catalyst Support Add 2.8 g of lanthanum nitrate, 0.55 g of ferric chloride, 0.30 g of cupric chloride, 0.46 g of nickel chloride, 0.35 g of molybdenum nitrate, 0.27 g of chromium nitrate and 0.55 g of citric acid into 30 g of water, stir to dissolve, dry at 120°C, and calcine the obtained solid at 380°C in air for 6 hours to obtain a catalyst carrier.

[0053] 1.2 Preparation of catalyst 50g of the catalyst carrier was immersed in 20mL of a mixed aqueous solution of 1.5% palladium nitrate and 0.5% platinum chloride at room temperature for 24h, and then dried at 105°C for 10h to obtain a catalyst precursor. The catalyst precursor was calcined at 350°C in an air atmosphere for 4h to obtain a catalytic wet oxidation catalyst.

[0054] Catalytic wet oxidation process The catalytic wet oxidation catalyst obtained in step 1 is used in the CWAO continuous reaction device to treat the acrylic acid model wastewater with COD = 30000 mg / L, and the TOC removal rate can reach 90%. Among them, the continuous reaction conditions are: reaction temperature is 230℃, reaction pressure is 5MPa, and the volume space velocity of acrylic acid wastewater is 3.0h -1 The oxidant is H2O2, and the actual dosage is 40% more than the amount required for complete oxidation of acrylic acid in the wastewater.

[0055] Example 8 Preparation of Catalytic Wet Oxidation Catalyst 1.1 Preparation of Catalyst Support Add 3.3 g of cerium chloride, 0.50 g of ferric nitrate, 0.28 g of copper chloride, 0.33 g of molybdenum chloride, 0.42 g of manganese nitrate, 0.35 g of chromium nitrate and 0.52 g of glycine into 25 g of water, stir to dissolve, dry at 120°C, and calcine the obtained solid at 350°C in air for 4 h to obtain a catalyst carrier.

[0056] 1.2 Preparation of catalyst 50g of the catalyst carrier was immersed in 20mL of a mixed aqueous solution of 3% palladium sulfate and 0.5% ruthenium sulfate at room temperature for 24h, and then dried at 105°C for 10h to obtain a catalyst precursor. The catalyst precursor was calcined at 350°C in an air atmosphere for 4h to obtain a catalytic wet oxidation catalyst.

[0057] Catalytic wet oxidation process The catalytic wet oxidation catalyst obtained in step 1 is used in the CWAO continuous reaction device to treat the acrylic acid model wastewater with COD = 60000 mg / L, and the TOC removal rate can reach 80%. Among them, the continuous reaction conditions are: reaction temperature is 250℃, reaction pressure is 6MPa, and the volume space velocity of acrylic acid wastewater is 1.0h -1 The oxidant is H2O2, and the actual dosage is 20% more than the amount required for complete oxidation of acrylic acid in the wastewater.

[0058] The XRD patterns of the catalyst samples in Examples 1 to 8 are as follows: Figure 1 shown.

[0059] The scanning electron microscope photo of the catalyst prepared in Example 1 and the corresponding element spectrum are as follows: Figure 2 As shown, (a) is a scanning electron microscope photo of the catalyst of Example 1, and (b) is an energy spectrum diagram of the corresponding elements of the catalyst of Example 1, with a scale of 10 μm.

[0060] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for preparing a catalytic wet oxidation catalyst containing a rare earth metal, characterized in that: The steps include: S1, heating a solid mixture containing a metal precursor and a combustion-supporting material, and then calcining the heated solid mixture to obtain a catalyst carrier; The metal precursor is selected from metal salts of at least five elements selected from iron, cobalt, nickel, manganese, molybdenum, magnesium, chromium, copper, lanthanum, neodymium, cerium, and gadolinium, and the metal salts of at least five elements include at least one metal salt of lanthanum, neodymium, cerium, and gadolinium; S2, impregnating the catalyst support in an aqueous solution containing a noble metal salt, and then drying the impregnated catalyst support to obtain a catalyst precursor; S3, calcining the catalyst precursor II to obtain the rare earth metal-containing catalytic wet oxidation catalyst.

2. The preparation method according to claim 1, characterized in that: In step S1, the combustion-supporting material is selected from at least one of citric acid, glycine, urea, and ethylene glycol.

3. The preparation method according to claim 1, characterized in that: In step S1, the weight ratio of the metal precursor to the combustion aid is 1:4-6:1 based on the weight of the metal element in the metal precursor.

4. The preparation method according to claim 1, characterized in that: In step S1, the solid mixture containing the metal precursor and the combustion aid is obtained by mixing and grinding the raw materials containing the metal precursor and the combustion aid; or, the raw materials containing the metal precursor and the combustion aid are added into water and stirred to obtain a mixed liquid, and the mixed liquid is dried to obtain the solid mixture.

5. The preparation method according to claim 1, characterized in that: In step S1, the heating conditions include: heating at 100° C. to 600° C. to induce self-propagating combustion of the solid mixture until completion.

6. The preparation method according to claim 1, characterized in that: In step S2, the noble metal salt is selected from metal salts of at least one element selected from ruthenium, rhodium, palladium, osmium, iridium, and platinum.

7. The preparation method according to claim 1, characterized in that: In step S2, the loading concentration of the noble metal salt in the catalyst precursor is 0.1 wt.% to 5 wt.% in terms of the weight percentage of the heavy metal element.

8. The preparation method according to claim 1, characterized in that: The conditions of calcination I and calcination II independently include: calcination temperature of 200° C. to 600° C., and calcination time of 0.5 h to 12 h.

9. The rare earth metal-containing catalytic wet oxidation catalyst prepared by the preparation method according to any one of claims 1 to 8, characterized in that: The rare earth metal-containing catalytic wet oxidation catalyst comprises a carrier and a noble metal supported on the carrier; The carrier includes a high entropy oxide carrier, and the high entropy oxide carrier contains an oxide of at least one element selected from the group consisting of lanthanum, neodymium, cerium, and gadolinium.

10. Use of the rare earth metal-containing catalytic wet oxidation catalyst prepared by the preparation method according to any one of claims 1 to 8 in catalytic wet oxidation degradation of acrylic acid wastewater.

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