CN114950457A - Preparation method of iron-doped cerium vanadate-based solid solution flue gas denitration catalyst - Google Patents

Preparation method of iron-doped cerium vanadate-based solid solution flue gas denitration catalyst Download PDF

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CN114950457A
CN114950457A CN202210523495.0A CN202210523495A CN114950457A CN 114950457 A CN114950457 A CN 114950457A CN 202210523495 A CN202210523495 A CN 202210523495A CN 114950457 A CN114950457 A CN 114950457A
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iron
cerium
vanadate
solid solution
based solid
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王莉
王俊波
陆胤
周香香
徐滔
李绮雯
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Zhejiang Shuren University
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
    • B01J23/76—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/84—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36 with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
    • B01J23/847—Vanadium, niobium or tantalum or polonium
    • B01J23/8472—Vanadium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/86—Catalytic processes
    • B01D53/8621—Removing nitrogen compounds
    • B01D53/8625—Nitrogen oxides
    • B01D53/8628—Processes characterised by a specific catalyst
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/002—Mixed oxides other than spinels, e.g. perovskite
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    • B01J35/613—
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/03—Precipitation; Co-precipitation
    • B01J37/036—Precipitation; Co-precipitation to form a gel or a cogel
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2258/00—Sources of waste gases
    • B01D2258/02—Other waste gases
    • B01D2258/0283—Flue gases
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2523/00—Constitutive chemical elements of heterogeneous catalysts
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02C—CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]
    • Y02C20/00—Capture or disposal of greenhouse gases
    • Y02C20/10—Capture or disposal of greenhouse gases of nitrous oxide (N2O)

Abstract

The invention discloses a preparation method of an iron-doped cerium vanadate-based solid solution catalyst, which adopts an improved sol-gel method to dissolve soluble ferric salt and cerium salt in water respectively, and the soluble ferric salt and the cerium salt are mixed with soluble vanadate under the action of a complexing agent; stirring in a constant-temperature water bath, and simultaneously dropwise adding a proper amount of gelling agent to obtain brick red iron cerium vanadium gel; and fully washing the gel, removing impurities, drying and calcining to obtain the iron-doped cerium vanadate-based solid solution. Iron-doped cerium vanadate-based solid solution denitration catalyst Fe prepared in such a way x Ce 1‑x VO 4 The Fe doping amount can reach 75%, the Fe doping is uniform and pure, a pore channel structure is formed in the catalyst, the specific surface area is large, the thermal stability is high, the denitration efficiency is high, and N is high 2 The nitrogen has high selectivity and simultaneously has good sulfur resistance and water resistance.

Description

Preparation method of iron-doped cerium vanadate-based solid solution flue gas denitration catalyst
Technical Field
The invention belongs to the field of preparation of flue gas denitration catalysts, and particularly relates to a preparation method of an iron-doped cerium vanadate-based solid solution flue gas denitration catalyst.
Background
The denitration catalyst has a plurality of types, wherein CeO 2 The denitration catalyst has attracted attention because of its strong oxygen storage capacity and reducing property, but it is easily deactivated in the denitration process. Cerium vanadate CeVO 4 The catalyst has high thermal stability, has more acid sites, can inhibit the oxidation of ammonia in selective catalytic reduction in the denitration process, but has not high water resistance and sulfur resistance. Cerium vanadate is often doped with metals or metal oxides such as tin and zirconium to modify these disadvantages. The tin-doped cerium vanadate can improve the electron transfer between cerium and vanadium and improve the denitration effect; zirconium-doped cerium vanadate can promote the conversion between zirconium and cerium, but none of these dopings improves the disadvantage of the cerium vanadate catalyst that the water and sulfur resistance is poor at low temperature. It has been found that iron catalysts are subject to SO 2 And H 2 Little influence of O, e.g. iron vanadate FeVO 4 /TiO 2 Has better sulfur resistance at 240 ℃, but poor water resistance, but Fe due to different ionic radius and crystalline phase structure 3+ Ions are difficult to dope into cerium vanadate.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a preparation method of an iron-doped cerium vanadate-based solid solution, which adopts an improved sol-gel method, the Fe doping proportion can reach 75%, and the doping is uniform, so that the solid solution is formed. The catalyst has good sulfur-resistant and water-resistant performance. The specific technical scheme is as follows:
a preparation method of an iron-doped cerium vanadate-based solid solution flue gas denitration catalyst comprises the following steps:
(1) respectively dissolving soluble ferric salt and soluble cerium salt in water, mixing, dropwise adding a complexing agent, and uniformly stirring to obtain a solution A; dissolving soluble vanadate in water to obtain a solution B;
wherein the sum of the molar amounts of the soluble ferric salt and the soluble cerium salt is equal to the molar amount of the soluble vanadate;
(2) mixing the solution A and the solution B, adding urea, adjusting the pH value of the solution to 9-11, stirring in a constant-temperature water bath at 50-70 ℃, and simultaneously dropwise adding another gelatinizing agent until red gel appears to obtain brick red iron cerium vanadium gel;
(3) and heating the brick red iron-cerium-vanadium gel at a constant temperature of 170-200 ℃ for 8-15 hours under a high-pressure closed condition, cooling to room temperature, taking out, performing centrifugal filtration, fully washing with an organic solvent and water, removing inorganic ions, drying to remove moisture, and finally calcining at 500-700 ℃ for 8-16 hours to obtain the iron-doped cerium vanadate-based solid solution.
Further, the complexing agent is selected from any one of citric acid, sucrose and glucose, and the gelling agent is selected from propylene oxide; the molar quantity of the complexing agent is equal to the sum of the molar quantities of the soluble ferric salt and the soluble cerium salt.
Further, the complexing agent in the step (1) is citric acid, and the gelling agent in the step (2) is propylene oxide. Citric acid is taken as a complexing agent, the contained carboxylic acid functional group can better complex metal ions, propylene oxide is taken as a gelling agent and can generate a network structure in situ, the occurrence of segregation phenomenon is hindered,
further, the organic solvent is selected from any one of methanol, ethanol and ethylene glycol.
Furthermore, ferric nitrate salt is more soluble than ferric sulfate salt, cerium nitrate is more soluble than ammonium cerium nitrate, sodium vanadate is more soluble than ammonium metavanadate, the soluble ferric salt is selected from any one of ferric nitrate and ferric sulfate, the soluble cerium salt is selected from any one of cerium nitrate and ammonium cerium nitrate, and the soluble vanadium salt is selected from any one of sodium vanadate or ammonium metavanadate.
Further, in the step (2), the pH value of the solution is adjusted to 10, and the solution is stirred in a constant-temperature water bath at 60 ℃. At a pH of 10, iron ions are not readily formed into Fe (OH) 3 Precipitated and vanadate VO 4 3- Will not be converted into VO 3 - Vanadate is more easily generated.
Further, in the step (3), the brick red iron cerium vanadium gel is heated at a constant temperature of 180 ℃ for 12 hours under a high-pressure closed condition, and is finally calcined at 650 ℃ for 12 hours to obtain the iron-doped cerium vanadate-based solid solution. The iron-doped cerium vanadate-based solid solution with pure crystal phase can be generated under high temperature and high pressure.
Fe-doped cerium vanadate-based solid solution flue gas denitration catalyst prepared according to preparation method x Ce 1-x VO 4 。
Compared with the prior art, the invention has the following beneficial effects:
compared with other synthesis methods such as a hydrothermal method, a coprecipitation method and the like, the iron-doped cerium vanadate Ce synthesized by the improved sol-gel method 1-x Fe x VO 4 The catalyst is more fully mixed among atoms, and the gelling agent enables Fe ions and Ce ions to be fixed in the network-shaped gel, so that the movement of metal ions is hindered, the occurrence of segregation is effectively hindered, and a solid solution is formed; fe 3+ Ion substitution of Ce 4+ After the ion, the coordination mode is composed of a six-coordination octahedral structure (FeO) 6 ) Converted into an eight coordinate cubic structure (FeO) 8 ) The binding capacity to lattice oxygen is greatly weakened, so that the reaction activity of the lattice oxygen is obviously improved, the activation energy of catalytic reaction is reduced, and the catalytic activity of defect oxygen is improved. The iron-doped cerium vanadate Ce obtained by the method 1-x Fe x VO 4 The catalyst has good denitration effect and is doped with Fe 3+ The highest amount can reach 75 percent, and the water-resistant and sulfur-resistant rubber has good water-resistant and sulfur-resistant performance. The catalytic activity is obviously superior to that of the Ce with low doping amount synthesized by a hydrothermal method and a coprecipitation method 1-x Fe x VO 4 A solid solution; the formed iron-doped cerium vanadate-based solid solution is pure and uniform in doping and has no other impuritiesThe average particle size of the mass phase is between 20 and 39nm, and the specific surface area is as high as 54 to 76m 2 G, N at 300 ℃ 2 The selectivity is as high as 99%, side reactions are few, and a pore structure is formed inside; meanwhile, the catalyst has good sulfur resistance and water resistance.
Drawings
FIG. 1 shows NO removal rates for catalysts of different ratios at different temperatures.
FIG. 2N at different temperatures for different catalysts 2 The selection rate.
FIG. 3 is Ce at 300 DEG C 0.50 Fe 0.50 VO 4 Sulfur and water resistance performance curve of the catalyst.
FIG. 4 shows different Fe-doped CeVO 4 XRD spectrum of the catalyst, wherein, figure (a) is CeVO 4 、Fe 0.25 Ce 0.75 VO 4 、 Fe 0.50 Ce 0.50 VO 4 And Fe 0.75 Ce 0.25 VO 4 XRD pattern of (a); fig. (b) is a partially enlarged XRD pattern.
FIG. 5 is Ce 0.50 Fe 0.50 VO 4 The elements of the catalyst are jigsaw.
FIG. 6 shows an XPS spectrum of a catalyst, in which CeVO is shown in graph (a) 4 And Fe 0.50 Ce 0.50 VO 4 Ce 3d XPS spectra of (a); FIG. b shows FeVO 4 And Fe 0.50 Ce 0.50 VO 4 Fe 2p XPS spectrum of (a); diagram (c) is CeVO 4 、Fe 0.50 Ce 0.50 VO 4 And FeVO 4 V2 p XPS spectrum of (a); diagram (d) is CeVO 4 、Fe 0.50 Ce 0.50 VO 4 And FeVO 4 O1s XPS spectrum of (a).
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments, and the objects and effects of the present invention will become more apparent, it being understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.
Example 1
The stoichiometric ratio of Ce (NO) 3 ) 3 ·6H 2 O：Fe(NO 3 ) 3 ·9H 2 Dissolving the reagents O1: 3 in water respectively, and dripping citric acid with the same molar amount as the mixed solution after mixing to obtain a solution A; will react with Ce (NO) 3 ) 3 ·6H 2 O、 Fe(NO 3 ) 3 ·9H 2 O mixed solution of Na in equimolar amount 3 VO 4 Adding a proper amount of water to dissolve to obtain a solution B; a, B solution is mixed, urea is added, the pH value of the solution is adjusted to 9, the solution is magnetically stirred in a constant temperature water bath kettle at 50 ℃, and propylene oxide solution is dripped until iron-cerium-vanadium gel is obtained; transferring the gel into a hydrothermal kettle, heating at the constant temperature of 170 ℃ for 8 hours, cooling to room temperature, taking out, performing centrifugal filtration, fully washing with ethanol and water to remove inorganic organic ions such as sodium, nitrate radical and the like, drying to remove water to obtain yellow powder, and finally calcining in a muffle furnace at 500 ℃ for 8 hours to obtain the iron-doped cerium vanadate-based solid solution Ce 0.25 Fe 0.75 VO 4 . BET specific surface area S59 m 2 In terms of/g, the mean particle size is 22 nm.
Example 2
The stoichiometric ratio of Ce (NO) 3 ) 3 ·6H 2 O：Fe(NO 3 ) 3 ·9H 2 Dissolving the reagents O1: 1 in water respectively, and dripping citric acid with the same molar amount as the mixed solution after mixing to obtain a solution A; will react with Ce (NO) 3 ) 3 ·6H 2 O、 Fe(NO 3 ) 3 ·9H 2 O mixed solution of NH in equimolar amount 4 VO 3 Adding a proper amount of water to dissolve to obtain a solution B; mixing A, B solution, adding urea, adjusting the pH value of the solution to 11, magnetically stirring in a constant-temperature water bath at 70 ℃, and dropwise adding propylene oxide solution until iron-cerium-vanadium gel is obtained; transferring the gel into a hydrothermal kettle, heating at the constant temperature of 200 ℃ for 15 hours, cooling to room temperature, taking out, performing centrifugal filtration, fully washing with methanol and water to remove inorganic organic ions such as sodium, nitrate radical and the like, drying to remove moisture to obtain yellow powder, and finally calcining in a muffle furnace at 700 ℃ for 16 hours to obtain the iron-doped cerium vanadate-based Ce solid solution 0.50 Fe 0.50 VO 4 . BET specific surface area S ═ 74m 2 (ii)/g, average particle size at 25 nm.
Example 3
The stoichiometric ratio of Ce (NO) 3 ) 3 ·6H 2 O：Fe 2 (SO 4 ) 3 ·9H 2 Dissolving the reagents O1: 1 in water respectively, and dripping glucose with the same molar amount as the mixed solution after mixing to obtain a solution A; will react with Ce (NO) 3 ) 3 ·6H 2 O、 Fe 2 (SO 4 ) 3 ·9H 2 O mixed solution of NH in equimolar amount 4 VO 3 Adding a proper amount of water to dissolve to obtain a solution B; a, B solution is mixed, urea is added, the pH value of the solution is adjusted to 9, the solution is magnetically stirred in a constant temperature water bath kettle at 60 ℃, and propylene oxide solution is dripped until iron cerium vanadium gel is obtained; transferring the gel into a hydrothermal kettle, heating at the constant temperature of 200 ℃ for 8 hours, cooling to room temperature, taking out, performing centrifugal filtration, fully washing with ethanol and water to remove inorganic organic ions such as sodium, nitrate radical and the like, drying to remove water to obtain yellow powder, and finally calcining in a muffle furnace at 650 ℃ for 16 hours to obtain the iron-doped cerium vanadate-based solid solution Ce 0.50 Fe 0.50 VO 4 . BET specific surface area S of 70m 2 (ii)/g, average particle size 28 nm.
Example 4
The stoichiometric ratio of Ce (NH) 4 ) 2 (NO 3 ) 6 ：Fe(NO 3 ) 3 ·9H 2 Dissolving the reagents O1: 1 in water respectively, and dripping sucrose with the same molar amount as the mixed solution after mixing to obtain a solution A; will react with Ce (NH) 4 ) 2 (NO 3 ) 6 、 Fe(NO 3 ) 3 ·9H 2 O mixed solution of Na in equimolar amount 3 VO 4 Adding a proper amount of water to dissolve to obtain a solution B; a, B solution is mixed, urea is added, the pH value of the solution is adjusted to 10, the solution is magnetically stirred in a constant temperature water bath kettle at 50 ℃, and propylene oxide solution is dripped until iron cerium vanadium gel is obtained; transferring the gel into a hydrothermal kettle, heating at 185 deg.C for 14 hr, cooling to room temperature, taking out, centrifuging, filtering, washing with ethylene glycol and water to remove inorganic and organic ions such as sodium and nitrate, drying to remove waterYellow powder, and finally calcining the yellow powder in a muffle furnace at 700 ℃ for 8 hours to obtain the iron-doped cerium vanadate-based solid solution Ce 0.50 Fe 0.50 VO 4 . BET specific surface area S of 66m 2 (ii)/g, average particle size 39 nm.
Example 5
The stoichiometric ratio Ce (NH) 4 ) 2 (NO 3 ) 6 ：Fe 2 (SO 4 ) 3 ·9H 2 Dissolving the reagents O1: 1 in water respectively, and dripping citric acid with the same molar amount as the mixed solution after mixing to obtain a solution A; will react with Ce (NH) 4 ) 2 (NO 3 ) 6 、 Fe 2 (SO 4 ) 3 ·9H 2 O mixed solution of NH in equimolar amount 4 VO 3 Adding a proper amount of water to dissolve to obtain a solution B; mixing A, B solution, adding urea, adjusting the pH value of the solution to 11, magnetically stirring in a constant-temperature water bath kettle at 65 ℃, and dropwise adding propylene oxide solution until iron-cerium-vanadium gel is obtained; transferring the gel into a hydrothermal kettle, heating at 190 ℃ for 15 hours at constant temperature, cooling to room temperature, taking out, centrifuging, filtering, fully washing with ethylene glycol and water to remove inorganic organic ions such as sodium, nitrate radical and the like, drying to remove water to obtain yellow powder, and calcining in a muffle furnace at 500 ℃ for 16 hours to obtain the iron-doped cerium vanadate-based Ce solid solution 0.5 Fe 0.5 VO 4 . BET specific surface area S of 68m 2 In terms of/g, the mean particle size is 37 nm.
Example 6
The stoichiometric ratio of Ce (NH) 4 ) 2 (NO 3 ) 6 ：Fe 2 (SO 4 ) 3 ·9H 2 Dissolving the reagents O to 3:1 in water respectively, and dripping cane sugar with the same molar amount as the mixed solution after mixing to obtain a solution A; will react with Ce (NH) 4 ) 2 (NO 3 ) 6 、 Fe 2 (SO 4 ) 3 ·9H 2 O mixed solution of Na in equimolar amount 3 VO 4 Adding a proper amount of water to dissolve to obtain a solution B; mixing A, B solution, adding urea, adjusting pH to 9, magnetically stirring at 60 deg.C in a constant temperature water bath, and adding dropwiseEpoxypropane solution until iron-cerium-vanadium gel is obtained; transferring the gel into a hydrothermal kettle, heating at the constant temperature of 170 ℃ for 12 hours, cooling to room temperature, taking out, performing centrifugal filtration, sufficiently washing with methanol and water to remove inorganic organic ions such as sodium, nitrate radical and the like, drying to remove moisture to obtain yellow powder, and finally calcining in a muffle furnace at 650 ℃ for 12 hours to obtain the iron-doped cerium vanadate-based Ce solid solution 0.25 Fe 0.75 VO 4 . BET specific surface area S of 70m 2 (ii)/g, average particle size 33 nm.
Example 7
The stoichiometric ratio of Ce (NH) 4 ) 2 (NO 3 ) 6 ：Fe(NO 3 ) 3 ·9H 2 Dissolving the reagents O to 3:1 in water respectively, and dripping citric acid with the same molar amount as the mixed solution after mixing to obtain a solution A; will react with Ce (NH) 4 ) 2 (NO 3 ) 6 、 Fe(NO 3 ) 3 ·9H 2 O mixed solution of Na in equimolar amount 3 VO 4 Adding a proper amount of water to dissolve to obtain a solution B; a, B solution is mixed, urea is added, the pH value of the solution is adjusted to 10, the solution is magnetically stirred in a constant temperature water bath kettle at 60 ℃, and propylene oxide solution is dripped until iron-cerium-vanadium gel is obtained; transferring the gel into a hydrothermal kettle, heating at the constant temperature of 180 ℃ for 12 hours, cooling to room temperature, taking out, performing centrifugal filtration, sufficiently washing with ethylene glycol and water to remove inorganic organic ions such as sodium, nitrate radical and the like, drying to remove water to obtain yellow powder, and finally calcining in a muffle furnace at 650 ℃ for 12 hours to obtain the iron-doped cerium vanadate-based Ce solid solution 0.25 Fe 0.75 VO 4 . BET specific surface area S of 61m 2 (ii)/g, average particle size at 38 nm.
Comparative example 1
Mixing Fe (NO) 3 ) 3 ·9H 2 Dissolving the reagent O in water, adding equimolar citric acid after dissolving, stirring and dissolving uniformly, and recording as a solution A; will react with Fe (NO) 3 ) 3 ·9H 2 O equimolar amount of Na 3 VO 4 Adding a proper amount of water to dissolve to obtain a solution B; mixing A, B solution, adding urea, and adjusting pH to10, magnetically stirring at 60 ℃ in a constant-temperature water bath kettle, and dropwise adding a propylene oxide solution until ferric vanadate gel is obtained; transferring the gel into a hydrothermal kettle, heating at the constant temperature of 180 ℃ for 12 hours, cooling to room temperature, taking out, performing centrifugal filtration, fully washing with ethanol and water to remove inorganic and organic ions such as sodium, nitrate radical and the like, drying to remove water to obtain yellow powder, and finally calcining in a muffle furnace at 650 ℃ for 12 hours to obtain a solid solution FeVO 4 . BET specific surface area S58 m 2 In terms of/g, the mean particle size is 20 nm.
Comparative example 2
Adding Ce (NO) 3 ) 3 ·6H 2 Dissolving the reagent O in water, adding equimolar glucose after dissolving, stirring and dissolving uniformly to obtain a solution A; mixing equimolar amount of NH 4 VO 3 Adding a proper amount of water to dissolve to obtain a solution B; mixing the AB solution, adding urea, adjusting the pH value of the solution to 9, magnetically stirring in a constant-temperature water bath kettle at 60 ℃, and dropwise adding a propylene oxide solution until iron-cerium-vanadium gel is obtained; transferring the gel into a hydrothermal kettle, heating at the constant temperature of 180 ℃ for 12 hours, cooling to room temperature, taking out, centrifuging, filtering, fully washing with ethylene glycol and water to remove inorganic organic ions such as sodium, nitrate radical and the like, drying to remove water to obtain yellow powder, and finally calcining in a muffle furnace at 650 ℃ for 12 hours to obtain the iron-doped cerium vanadate-based solid solution CeVO 4 . BET specific surface area S54 m 2 (ii)/g, average particle size at 38 nm.
Catalyst Ce prepared in examples 1, 2 and 6 and comparative examples 1-2 and in different proportions 1-x Fe x VO 4 (x is 0,0.25,0.50, 0.75,1.00), tabletting and sieving, taking particles with the size of 40-60 meshes, taking 200mg of the particles, putting the particles into a quartz tube reactor with the diameter of 8mm, plugging quartz wool into the quartz tube reactor from top to bottom to prevent air flow from blowing off, and carrying out a denitration experiment under the following experimental conditions: wherein [ NO ]]＝500ppm， [NH 3 ]＝500ppm，[O 2 ]3 vol.%, balance gas N 2 200mg of catalyst, and 500 mL/min of total gas flow -1 ， GHSV＝100000h -1 . The results of the experiment are shown in FIGS. 1 and 2.
FIG. 1 shows the removal of different catalysts under the same conditionsEfficiency of NO, wherein Ce 0.50 Fe 0.50 VO 4 The solid solution catalyst shows the best catalytic effect at 300 ℃, and the highest denitration efficiency X NO 99%. Overall, the doped catalyst is more phase pure CeVO than the pure phase 4 And FeVO 4 The catalyst has higher catalytic efficiency.
FIG. 2 shows N at different temperatures for different catalysts 2 All the composite catalysts N at 300 DEG C 2 The selectivity exceeds 99 percent, and is not lower than 98 percent in the temperature range of 200 ℃ and 400 ℃. Much higher than pure phase CeVO 4 And FeVO 4 A catalyst. Taking Ce with highest denitration rate 0.50 Fe 0.50 VO 4 Catalyst, tabletting and sieving, selecting 40-60 mesh particles of 200mg, loading into an adaptive tube reactor with the diameter of 8mm, plugging quartz wool up and down to prevent air flow from blowing off, and introducing SO 2 And H 2 O, reaction conditions are as follows: [ NO ]] ＝500ppm，[NH 3 ]＝500ppm，[O 2 ]＝3vol.％，[H 2 O]＝10％，[SO 2 ]200ppm of balance gas N 2 200mg of catalyst, 500 mL/min of total gas flow -1 ，GHSV＝100000h -1 To obtain Ce 0.50 Fe 0.50 VO 4 Sulfur and water resistance performance curve of the catalyst. As can be seen in FIG. 3, with H 2 The NO catalytic activity gradually decreases from 99% to 93% by the addition of O vapor. Remove H 2 O steam, the catalytic activity gradually increased to 96.7%. When H is present 2 O and SO 2 When added simultaneously, the NO catalytic activity gradually decreases from 99% to 91%. Removing H 2 O and SO 2 The catalytic activity gradually increased to 96.7%.
FIG. 4 shows CeVO 4 ,Fe 0.25 Ce 0.75 VO 4 ,Fe 0.50 Ce 0.50 VO 4 ,Fe 0.75 Ce 0.25 VO 4 And Fe 0 VO 4 The XRD patterns of the five catalysts show that the solid solution still maintains CeVO along with the increase of the Fe doping amount 4 Crystal structure of (1), but due to Fe 3+ Has an ionic radius (49pm) smaller than Ce 4+ (103.8pm), increased diffraction angle according to the scherrer equation 2 theta, and a partial magnification 4: (b) The results agree.
FIG. 5 shows Fe 0.50 Ce 0.50 VO 4 The catalyst has the elements which are arranged in a jigsaw, and as can be seen from the figure, all the elements are uniformly distributed without aggregation, which indicates that solid solution is generated.
Figure 6 gives the XPS spectrum of the catalyst. Wherein (a) in FIG. 6 shows CeVO 4 And Fe 0.50 Ce 0.50 VO 4 The Ce 3d XPS spectrum shows that the average valence of Ce is increased after Fe is doped, and that Ce loses electrons. FIG. 6 (b) shows FeVO 4 And Fe 0.50 Ce 0.50 VO 4 The Ce 3d XPS spectrum of shows that Fe loses electrons and the average valence is increased. FIG. 6 (c) shows CeVO 4 、Fe 0.50 Ce 0.50 VO 4 And FeVO 4 The V2 p XPS spectrum of (A) shows that the average valence of V is reduced and V obtains electrons. FIG. 6 (d) shows CeVO 4 、Fe 0.50 Ce 0.50 VO 4 And FeVO 4 The XPS spectrum of O1s shows that Fe is doped with Fe 0.50 Ce 0.50 VO 4 Catalyst surface activity O α Obviously increases and obviously improves the catalytic activity.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and although the invention has been described in detail with reference to the foregoing examples, it will be apparent to those skilled in the art that various changes in the form and details of the embodiments may be made and equivalents may be substituted for elements thereof. All modifications, equivalents and the like which come within the spirit and principle of the invention are intended to be included within the scope of the invention.

Claims (8)

1. A preparation method of an iron-doped cerium vanadate-based solid solution flue gas denitration catalyst is characterized by comprising the following steps of: the preparation method comprises the following steps:
(1) respectively dissolving soluble ferric salt and soluble cerium salt in water, mixing, dropwise adding a complexing agent, and uniformly stirring to obtain a solution A; dissolving soluble vanadate in water to obtain a solution B;
wherein the sum of the molar amounts of the soluble ferric salt and the soluble cerium salt is equal to the molar amount of the soluble vanadate;
(2) mixing the solution A and the solution B, adding urea, adjusting the pH value of the solution to 9-11, stirring in a constant-temperature water bath at 50-70 ℃, and simultaneously dropwise adding another gelatinizing agent until red gel appears to obtain brick red iron cerium vanadium gel;
(3) and heating the brick red iron-cerium-vanadium gel at a constant temperature of 170-200 ℃ for 8-15 hours under a high-pressure closed condition, cooling to room temperature, taking out, centrifuging, filtering, fully washing with an organic solvent and water, removing inorganic ions, drying to remove water, and finally calcining at 500-700 ℃ for 8-16 hours to obtain the iron-doped cerium vanadate-based solid solution.
2. The method for preparing an iron-doped cerium vanadate-based solid solution catalyst according to claim 1, wherein the complexing agent is selected from any one of citric acid, sucrose and glucose, and the gelling agent is selected from propylene oxide; the molar quantity of the complexing agent is equal to the sum of the molar quantities of the soluble ferric salt and the soluble cerium salt.
3. The method for preparing an iron-doped cerium vanadate-based solid solution catalyst according to claim 2, wherein the complexing agent in the step (1) is citric acid, and the gelling agent in the step (2) is propylene oxide.
4. The method of preparing an iron-doped cerium vanadate-based solid solution catalyst according to claim 1, wherein the organic solvent is selected from any one of methanol, ethanol and ethylene glycol.
5. The method for preparing the iron-doped cerium vanadate-based solid solution flue gas denitration catalyst according to claim 1, wherein the soluble iron salt is selected from any one of iron nitrate and iron sulfate, the soluble cerium salt is selected from any one of cerium nitrate and ammonium cerium nitrate, and the soluble vanadium salt is selected from any one of sodium vanadate or ammonium metavanadate.
6. The method for preparing an iron-doped cerium vanadate-based solid solution catalyst according to claim 1, wherein in the step (2), the solution is adjusted to have a pH value of 10 and stirred in a constant-temperature water bath at 60 ℃.
7. The method for preparing the iron-doped cerium vanadate-based solid solution catalyst according to claim 1, wherein in the step (3), the brick red iron-cerium-vanadium gel is heated under a high-pressure closed condition at a constant temperature of 180 ℃ for 12 hours, and finally calcined at 650 ℃ for 12 hours to obtain the iron-doped cerium vanadate-based solid solution.
8. Fe-doped cerium vanadate-based solid solution flue gas denitration catalyst prepared by the preparation method according to any one of claims 1 to 7 x Ce 1-x VO 4 。
CN202210523495.0A 2022-05-13 2022-05-13 Preparation method of iron-doped cerium vanadate-based solid solution flue gas denitration catalyst Pending CN114950457A (en)

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