CN113908837A - MOFs derivative denitration catalyst, preparation method and application thereof - Google Patents
MOFs derivative denitration catalyst, preparation method and application thereof Download PDFInfo
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- 239000003054 catalyst Substances 0.000 title claims abstract description 93
- 239000012621 metal-organic framework Substances 0.000 title claims abstract description 28
- 238000002360 preparation method Methods 0.000 title claims abstract description 20
- 238000006243 chemical reaction Methods 0.000 claims abstract description 36
- 238000001354 calcination Methods 0.000 claims abstract description 35
- 229910015189 FeOx Inorganic materials 0.000 claims abstract description 21
- 239000013179 MIL-101(Fe) Substances 0.000 claims abstract description 10
- 239000002243 precursor Substances 0.000 claims abstract description 7
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 5
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 5
- 238000001035 drying Methods 0.000 claims abstract description 5
- 238000010438 heat treatment Methods 0.000 claims abstract description 5
- 239000002904 solvent Substances 0.000 claims abstract description 4
- 238000005406 washing Methods 0.000 claims abstract description 4
- 238000002156 mixing Methods 0.000 claims abstract description 3
- 150000002505 iron Chemical class 0.000 claims abstract 3
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical group CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 claims description 66
- 239000013078 crystal Substances 0.000 claims description 24
- KKEYFWRCBNTPAC-UHFFFAOYSA-N terephthalic acid group Chemical group C(C1=CC=C(C(=O)O)C=C1)(=O)O KKEYFWRCBNTPAC-UHFFFAOYSA-N 0.000 claims description 16
- 229910052757 nitrogen Inorganic materials 0.000 claims description 14
- 238000000034 method Methods 0.000 claims description 11
- 239000011148 porous material Substances 0.000 claims description 9
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 8
- 230000000694 effects Effects 0.000 claims description 8
- 230000008569 process Effects 0.000 claims description 4
- 239000003599 detergent Substances 0.000 claims description 2
- 229940044631 ferric chloride hexahydrate Drugs 0.000 claims description 2
- NQXWGWZJXJUMQB-UHFFFAOYSA-K iron trichloride hexahydrate Chemical compound O.O.O.O.O.O.[Cl-].Cl[Fe+]Cl NQXWGWZJXJUMQB-UHFFFAOYSA-K 0.000 claims description 2
- 150000003839 salts Chemical class 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 claims 1
- 230000035484 reaction time Effects 0.000 claims 1
- 239000007789 gas Substances 0.000 abstract description 25
- 239000003546 flue gas Substances 0.000 abstract description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 4
- 239000002912 waste gas Substances 0.000 abstract description 2
- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical compound O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 18
- 230000000052 comparative effect Effects 0.000 description 11
- 239000000243 solution Substances 0.000 description 11
- 239000006185 dispersion Substances 0.000 description 8
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 7
- 238000000024 high-resolution transmission electron micrograph Methods 0.000 description 7
- 239000007787 solid Substances 0.000 description 7
- 229910021578 Iron(III) chloride Inorganic materials 0.000 description 6
- RBTARNINKXHZNM-UHFFFAOYSA-K iron trichloride Chemical compound Cl[Fe](Cl)Cl RBTARNINKXHZNM-UHFFFAOYSA-K 0.000 description 6
- 239000011259 mixed solution Substances 0.000 description 6
- 239000000203 mixture Substances 0.000 description 6
- 229910001220 stainless steel Inorganic materials 0.000 description 6
- 239000010935 stainless steel Substances 0.000 description 6
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 4
- 230000003197 catalytic effect Effects 0.000 description 4
- -1 polytetrafluoroethylene Polymers 0.000 description 4
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 4
- 239000004810 polytetrafluoroethylene Substances 0.000 description 4
- 238000001179 sorption measurement Methods 0.000 description 4
- 230000009286 beneficial effect Effects 0.000 description 3
- 239000003795 chemical substances by application Substances 0.000 description 3
- 239000000376 reactant Substances 0.000 description 3
- 230000000630 rising effect Effects 0.000 description 3
- 239000004809 Teflon Substances 0.000 description 2
- 229920006362 Teflon® Polymers 0.000 description 2
- 239000002131 composite material Substances 0.000 description 2
- SZVJSHCCFOBDDC-UHFFFAOYSA-N iron(II,III) oxide Inorganic materials O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 description 2
- JKQOBWVOAYFWKG-UHFFFAOYSA-N molybdenum trioxide Chemical compound O=[Mo](=O)=O JKQOBWVOAYFWKG-UHFFFAOYSA-N 0.000 description 2
- 239000002159 nanocrystal Substances 0.000 description 2
- 238000003917 TEM image Methods 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 238000010531 catalytic reduction reaction Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000012512 characterization method Methods 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 239000002274 desiccant Substances 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N iron oxide Inorganic materials [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002082 metal nanoparticle Substances 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910000069 nitrogen hydride Inorganic materials 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N titanium dioxide Inorganic materials O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 1
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- 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
- B01J23/74—Iron group metals
- B01J23/745—Iron
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- 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
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- B01J35/00—Catalysts, in general, characterised by their form or physical properties
- B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
- B01J35/61—Surface area
- B01J35/615—100-500 m2/g
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- B01J35/64—Pore diameter
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- B01J37/08—Heat treatment
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Abstract
The invention relates to the technical field of waste gas treatment, and particularly relates to a MOFs derivative denitration catalyst, and a preparation method and application thereof. The catalyst is FeO with a regular octahedral structurexC; the preparation method comprises the following steps: mixing iron salt and a carbon source, dissolving in a solvent, reacting for a certain time at a certain temperature, washing, and drying to obtain a precursor MIL-101 (Fe); heating the precursor, introducing calcining gas for calcining to obtain the catalyst FeOxC; the invention also provides application of the prepared catalyst in denitration. The catalyst can be used for denitration at low temperatureTo 80% conversion and on H2O has certain resistance, and the catalyst does not influence the NO conversion rate and N under the condition of high water content in the flue gas2And (4) selectivity.
Description
Technical Field
The invention relates to the technical field of waste gas treatment, in particular to a MOFs derivative denitration catalyst, a preparation method and application.
Background
The nitrogen oxide NOx is one of main atmospheric pollutants in China, and in order to deal with serious harm brought by NOx emission, China sets up strict policy control emission aiming at various related industries. At present, the main denitration method at home and abroad is the Selective Catalytic Reduction (SCR) technology taking NH3 as a reducing agent. The industrially mature catalyst is V2O5-WO3(MoO3)/TiO2The catalyst has high working temperature, poor high-temperature selectivity and biotoxicity. In view of the above problems, it is important to search for some novel catalyst materials.
The MOFs-based composite material with the metal organic framework generally consists of a continuous phase and a disperse phase, has the advantages of MOFs porosity and large comparative area, and retains the catalytic function of metal, so that the application of the MOFs-based composite material in denitration treatment can be discussed.
Disclosure of Invention
The invention aims to provide a preparation method of a MOFs derivative denitration catalyst, which can obtain a MOFs derivative with a controllable crystal face.
In order to achieve the above purpose, the technical scheme of the invention is as follows:
a preparation method of a MOFs derivative denitration catalyst comprises the following steps:
(1) mixing ferric chloride hexahydrate and terephthalic acid, dissolving in N, N-dimethylformamide, reacting at the temperature of 100 ℃ and 120 ℃ for 18-20h, washing with absolute ethyl alcohol and/or N, N-dimethylformamide, and drying at the temperature of 50-70 ℃ for 12-18h to obtain a precursor MIL-101(Fe) solid;
(2) heating the precursor prepared in the step (1) at the speed of 1-3 ℃/min, introducing a calcining gas, and calcining at the temperature of 450-550 ℃ for 2-3h to obtain the catalyst FeOx/C。
Wherein the molar mass ratio of the ferric salt to the carbon source in the step (1) is 1:1-2: 1.
The calcining gas in the step (2) is CO and/or N2。
Go toOf step (c) CO with N2The volume ratio of (A) to (B) is 0.5:1 to 3: 1.
Further, the CO and N2In a volume ratio of 0.95:1 to 1.05: 1.
CO in the calcining gas is used as a crystal face directing agent and is preferentially adsorbed on Fe3O4The growth speed of the crystal face is weakened by the adsorption effect, the growth speed of the nano crystal can be controlled during calcination, so that more crystal faces (111) are exposed on the surface of the nano crystal, the crystal face change of the catalyst is regulated and controlled, metal nano particles with controllable forms and fixed crystal faces are prepared, the obtained metal oxide has large specific surface area and high porosity, the dispersion of active components and the mass and heat transfer in the reaction process are facilitated, the surface acidity and the oxidizing capability of the catalyst are provided, and the adsorption and the conversion of the catalyst to reactants are improved. The high-performance catalyst with a specific active crystal face can be prepared by utilizing the strong interaction of the guiding agent and the specific crystal face.
The above-mentioned preparation method and the selection of reactants, solvents, desiccants, detergents and the like in the preparation step thereof, and the selection of reaction conditions such as temperature, time and the like are all preferable, are not limited to the above selection, and may be replaced or omitted as appropriate depending on the effect.
The invention also provides the prepared MOFs derivative denitration catalyst and application thereof in denitration.
The catalyst is FeO with a regular octahedral structurexC, specific surface area of 260-300m2(ii)/g, the average pore diameter is 6.5-8.5 nm.
The catalyst surface is exposed to a high-activity (111) crystal face. (111) The crystal face increases the acidity of the catalyst surface, and can be better used for denitration application.
Compared with the prior art, the invention has the following advantages:
(1) the method can regulate and control the size and the shape of the crystal face by controlling the proportion of CO in the calcining atmosphere; the prepared MOFs derivative denitration catalyst has a specific active crystal face (111), a large specific surface area and a regular morphology, is beneficial to dispersion of active components and mass and heat transfer of reactants, and simultaneously generates rich acid sites on the surface to be beneficial to adsorption of ammonia species.
(2) The catalyst provided by the invention has the advantages of high catalytic activity, high selectivity, excellent resistance, strong stability, controllable form, fixed crystal face, capability of reaching 80% of conversion rate in low-temperature denitration, and capability of reacting on H2O has certain resistance, and the catalyst does not influence the NO conversion rate and N under the condition of high water content in the flue gas2And (4) selectivity.
Drawings
FIG. 1 is TEM and HRTEM images of catalysts prepared in examples 1-3 and comparative examples 1-2;
wherein (a) (b) the HRTEM image of comparative example 1,
(c) (d) is the HRTEM image of example 1,
(e) (f) is the HRTEM image of example 2,
(g) (h) is the HRTEM image of example 3,
(i) (j) is the HRTEM image of comparative example 2,
(k) (l) HRTEM image of precursor MIL-101 (Fe);
FIG. 2 is a graph of NH3-TPD characterization of catalysts made in comparative example 1 and examples 1-2;
FIG. 3 is a graph showing the nitrogen oxide conversion of catalysts prepared in examples 1-3 and comparative examples 1-2;
FIG. 4 is a graph showing the selectivity of nitrogen oxides for catalysts prepared in examples 1-3 and comparative examples 1-2;
FIG. 5 is an X-ray diffraction pattern of the catalysts prepared in examples 1-3 and comparative examples 1-2.
Detailed Description
The terms as used herein:
"prepared from … …" is synonymous with "comprising". The terms "comprises," "comprising," "includes," "including," "has," "having," "contains," "containing," or any other variation thereof, as used herein, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.
When an amount, concentration, or other value or parameter is expressed as a range, preferred range, or as a range of upper preferable values and lower preferable values, this is to be understood as specifically disclosing all ranges formed from any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether ranges are separately disclosed. For example, when the range "1 ~ 5" is disclosed, the ranges described should be construed to include the ranges "1 ~ 4", "1 ~ 3", "1 ~ 2 and 4 ~ 5", "1 ~ 3 and 5", and the like. When a range of values is described herein, unless otherwise stated, the range is intended to include the endpoints thereof and all integers and fractions within the range.
"and/or" is used to indicate that one or both of the illustrated conditions may occur, e.g., a and/or B includes (a and B) and (a or B).
The technical solutions of the present invention will be described in detail with reference to specific examples, but those skilled in the art will understand that the following examples are only illustrative of the present invention and should not be construed as limiting the scope of the present invention.
Example 1
A preparation method of a MOFs derivative denitration catalyst,
(1) taking 1.35 g FeCl3·6H2O (5mmol) and 0.83g terephthalic acid (5mmol) were dissolved in 30ml N, N-Dimethylformamide (DMF), stirred well at room temperature for 30 minutes to ensure dispersion of the solution, the prepared mixed solution was transferred to 100ml stainless steel autoclave lined with Teflon, reacted at 100 ℃ for 18 hours, the product was washed with absolute ethanol and DMF and collected, dried at 50 ℃ for 12 hours to obtain MIL-101(Fe) as a solid.
(2) Introducing CO and N at a rate of 400ml/min2The temperature of the calcining gas with the volume ratio of 0.5:1 is raised to 450 ℃ at the temperature rise rate of 1 ℃/min, and the calcining is carried out for 2h to obtain FeOxa/C (VCO0.5) catalyst.
The prepared catalyst FeOxThe specific surface area of the/C (VCO0.5) was 262m2In terms of/g, the mean pore diameter was 6.82 nm.
The prepared catalyst is applied to denitration by using FeOxthe/C (VCO0.5) catalyst was charged in a fixed-bed reactor and used in the form of a composition of 500ppm NO, 500ppm NH3，5％O2Equilibrium gas N2The flue gas test is carried out, the reaction temperature is 100-300 ℃, the reaction pressure is normal pressure, and the reaction airspeed is 30000h-1。
As shown in fig. 3 and 4, the NO conversion at steady state at a temperature of 300 ℃ was 72.36% with selectivity 97.01%.
Example 2
A preparation method of a MOFs derivative denitration catalyst,
(1) taking 1.35 g FeCl3·6H2O (5mmol) and 0.55g terephthalic acid (3.33mmol) were dissolved in 30ml N, N-Dimethylformamide (DMF), stirred well at room temperature for 30 minutes to ensure dispersion of the solution, the prepared mixed solution was transferred to a 100ml stainless steel autoclave lined with polytetrafluoroethylene, reacted at 105 ℃ for 18.5h, the product was washed with absolute ethanol and DMF and collected, dried at 55 ℃ for 14h to obtain MIL-101(Fe) as a solid.
(2) Introducing CO and N at a rate of 400ml/min2The temperature of the calcining gas with the volume ratio of 1:1 is raised to 480 ℃ at the temperature rising rate of 1.5 ℃/min, and the calcining is carried out for 2.2h to obtain FeOxa/C (VCO1) catalyst.
The prepared catalyst FeOxThe specific surface area of/C (VCO1) is 290m2In terms of/g, the mean pore diameter was 8.43 nm.
The prepared catalyst is applied to denitration by using FeOxthe/C (VCO1) catalyst was charged in a fixed-bed reactor and used in the form of a composition of 500ppm NO, 500ppm NH3，5％O2Equilibrium gas N2The flue gas test is carried out, the reaction temperature is 100-300 ℃, the reaction pressure is normal pressure, and the reaction airspeed is 30000h-1。
The NO conversion at steady state at a temperature of 300 ℃ was 82.35% with a selectivity of 97.69%.
Example 3
A preparation method of a MOFs derivative denitration catalyst,
(1) taking 1.35 g FeCl3·6H2O (5mmol) and 0.415g terephthalic acid (2.5mmol) were dissolved in 30ml N, N-dimethylIn Dimethylformamide (DMF), the solution was sufficiently stirred at room temperature for 30 minutes to ensure dispersion, and the prepared mixed solution was transferred to a 100ml stainless steel autoclave lined with polytetrafluoroethylene, reacted at 110 ℃ for 19 hours, and the product was washed with absolute ethanol and DMF and collected, and dried at 60 ℃ for 15 hours to obtain MIL-101(Fe) as a solid.
(2) Introducing CO and N at a rate of 400ml/min2The temperature of the calcining gas with the volume ratio of 2:1 is raised to 500 ℃ at the temperature rise rate of 2 ℃/min, and the calcining time is 2.5h, thus obtaining FeOxa/C (VCO2) catalyst.
The prepared catalyst FeOxThe specific surface area of the/C (VCO2) was 283m2In terms of/g, the mean pore diameter is 8.19 nm.
The prepared catalyst is applied to denitration by using FeOxthe/C (VCO2) catalyst was charged in a fixed-bed reactor and used in the form of a composition of 500ppm NO, 500ppm NH3，5％O2Equilibrium gas N2The flue gas test is carried out, the reaction temperature is 100-300 ℃, the reaction pressure is normal pressure, and the reaction airspeed is 30000h-1。
The NO conversion at steady state at a temperature of 300 ℃ was 85.02% with a selectivity of 98.58%.
Example 4
A preparation method of a MOFs derivative denitration catalyst,
(1) taking 1.35 g FeCl3·6H2O (5mmol) and 0.55g terephthalic acid (3.33mmol) were dissolved in 30ml N, N-Dimethylformamide (DMF), stirred well at room temperature for 30 minutes to ensure dispersion of the solution, the prepared mixed solution was transferred to a 100ml stainless steel autoclave lined with polytetrafluoroethylene, reacted at 105 ℃ for 18.5h, the product was washed with absolute ethanol and DMF and collected, dried at 55 ℃ for 14h to obtain MIL-101(Fe) as a solid.
(2) Introducing CO and N at a rate of 400ml/min2The temperature of the calcining gas with the volume ratio of 1:1 is raised to 480 ℃ at the temperature rising rate of 1.5 ℃/min, and the calcining is carried out for 2.2h to obtain FeOxa/C (VCO1:1) catalyst.
The prepared catalyst FeOxThe specific surface area of/C (VCO1:1) is 289m2In terms of/g, the mean pore diameter was 8.43 nm.
Preparation ofThe catalyst of (1) is applied to denitration by using FeOxthe/C (VCO1:1) catalyst was charged in a fixed-bed reactor and used in the form of 500ppm NO, 500ppm NH3，5％O2，20％H2O, balance gas N2The flue gas test is carried out, the reaction temperature is 100-300 ℃, the reaction pressure is normal pressure, and the reaction airspeed is 30000h-1。
The NO conversion at steady state at a temperature of 300 ℃ was 83.17% with a selectivity of 96.74%.
Comparative example 1
A preparation method of a MOFs derivative denitration catalyst,
(1) taking 1.35 g FeCl3·6H2O (5mmol) and 0.33g terephthalic acid (2mmol) were dissolved in 30ml N, N-Dimethylformamide (DMF), stirred well at room temperature for 30 minutes to ensure dispersion of the solution, the prepared mixed solution was transferred to a 100ml stainless steel autoclave lined with polytetrafluoroethylene, reacted at 115 ℃ for 19.5 hours, the product was washed with anhydrous ethanol and DMF and collected, dried at 65 ℃ for 16 hours to obtain MIL-101(Fe) as a solid.
(2) N was passed in at a rate of 400ml/min2The temperature of the calcining gas is raised to 525 ℃ at the temperature rising rate of 2.5 ℃/min, and the calcining is carried out for 3h to obtain FeOx/C(VN2) A catalyst.
The prepared catalyst FeOx/C(VN2) Has a specific surface area of 206m2In terms of a/g, the mean pore diameter is 5.32 nm.
The prepared catalyst is applied to denitration by using FeOx/C(VN2) The catalyst was packed in a fixed bed reactor and used in the form of 500ppm NO, 500ppm NH3，5％O2Equilibrium gas N2The flue gas test is carried out, the reaction temperature is 100-300 ℃, the reaction pressure is normal pressure, and the reaction airspeed is 30000h-1。
The NO conversion at steady state at a temperature of 300 ℃ was 42.30% with a selectivity of 94.02%.
Comparative example 2
A preparation method of a MOFs derivative denitration catalyst,
(1) taking 1.35 g FeCl3·6H2O (5mmol) and 0.277g terephthalic acid (1.67mmol) was dissolved in 30ml N, N-Dimethylformamide (DMF), stirred well at room temperature for 30 minutes to ensure dispersion of the solution, the prepared mixed solution was transferred to a 100ml stainless steel autoclave lined with Teflon, reacted at 120 ℃ for 20 hours, the product was washed with absolute ethanol and DMF and collected, dried at 70 ℃ for 18 hours to give MIL-101(Fe) as a solid.
(2) Introducing CO calcining gas at a rate of 400ml/min, heating to 550 ℃ at a heating rate of 3 ℃/min, and calcining for 3h to obtain FeOxa/C (VCO) catalyst.
The prepared catalyst FeOxThe specific surface area of the/C (VCO) was 247m2In terms of/g, the mean pore diameter was 8.51 nm.
The prepared catalyst is applied to denitration by using FeOxthe/C (VCO) catalyst was charged in a fixed-bed reactor and used in the form of a composition of 500ppm NO, 500ppm NH3，5％O2Equilibrium gas N2The flue gas test is carried out, the reaction temperature is 100-300 ℃, the reaction pressure is normal pressure, and the reaction airspeed is 30000h-1。
The NO conversion at steady state at a temperature of 300 ℃ was 83.68% with a selectivity of 98.46%.
From examples 1 to 3, it can be seen that as the volume fraction of CO in the calcination gas increases, the specific surface area and the pore size of the catalyst prepared by calcination increase, and the conversion rate and selectivity of nitrogen oxides increase. When CO and N are present2After the volume ratio reaches 1:1, the CO content is increased, the performance of the catalyst is slightly influenced, and therefore, the CO and the N are preferably selected2A calcining gas in a volume ratio of 0.95:1 to 1.05: 1.
It can be seen from comparative example 1 and examples 1-3 that when the calcination gas contains CO, the catalytic performance of the catalyst can be significantly improved, and CO, as a crystal plane directing agent, can well expose a high-activity (111) crystal plane to the catalyst, thereby preparing the catalyst with more excellent denitration performance.
From examples 2 and 4, it can be seen that the catalyst prepared by the method has stable activity and catalytic performance when the water content of the flue gas is high, and shows good water resistance.
Wherein, from FIG. 1To see that when the calcining gas had only N2When the catalyst is prepared, the prepared catalyst has a (100) crystal face; when CO and N are in the calcining gas2When the volume ratio is 0.5:1, the crystal faces of the prepared catalyst are (111) and (100) mixed; when CO and N are in the calcining gas2When the volume ratio is 1:1, the prepared catalyst presents a typical regular octahedron shape, and the crystal lattice stripes are consistent with the (111) plane, which shows that the catalyst only has a high-activity (111) crystal plane; when CO and N are in the calcining gas2When the volume ratio is 2:1 or only CO exists, the crystal face of the catalyst is not changed. I.e. when CO and N are present in the calcining gas2When the volume ratio reaches 1:1, the catalyst has the best crystal face activity, the content of CO does not need to be additionally increased, and meanwhile, the damage of excessive CO to personnel, environment and the like can be avoided.
As can be seen from FIG. 2, as more (111) crystal planes are exposed on the surface of the catalyst, the acidity of the surface of the catalyst is continuously improved, and the content of basic NH is improved3Adsorption and conversion are beneficial to SCR reaction.
As can be seen from the graphs in FIGS. 3 and 4, the catalyst prepared by the invention has excellent NH3-SCR performance, and can achieve a removal rate of nitrogen oxides of more than 70% within a temperature range of 250-300 ℃, a removal rate of more than 80 at 300 ℃ and a selectivity of nitrogen oxides of more than 95%.
XRD diffraction pattern of the catalyst corresponds to Fe3O4As can be seen from FIG. 5, as CO and N in the calcination gas flow, CO and N are mixed2The volume ratio is increased, the crystallinity of the catalyst is improved when the ratio of CO to N is increased2After the volume ratio reaches 1:1, the crystal structure of the catalyst cannot be changed by increasing the volume ratio of CO.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Furthermore, those skilled in the art will appreciate that while some embodiments herein include some features included in other embodiments, rather than other features, combinations of features of different embodiments are meant to be within the scope of the invention and form different embodiments. For example, in the claims above, any of the claimed embodiments may be used in any combination. The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.
Claims (10)
1. A preparation method of a MOFs derivative denitration catalyst is characterized by comprising the following steps:
(1) mixing iron salt and a carbon source, dissolving in a solvent, reacting for a certain time at a certain temperature, washing, and drying to obtain a precursor MIL-101 (Fe);
(2) heating the precursor prepared in the step (1), introducing calcining gas for calcining to obtain the catalyst FeOx/C。
2. The method for preparing a MOFs derivative denitration catalyst according to claim 1, wherein the iron salt in step (1) is ferric chloride hexahydrate; the carbon source is terephthalic acid; the molar mass ratio of the ferric salt to the carbon source is 1:1-3: 1; the reaction temperature is 100-120 ℃, and the reaction time is 18-20 h; the solvent is N, N-dimethylformamide, and the detergent for washing is absolute ethyl alcohol and/or N, N-dimethylformamide; the drying temperature is 50-70 ℃, and the drying time is 12-18 h.
3. The method according to claim 1, wherein the temperature of step (2) is increased at a rate of 1-3 ℃/min, the calcination temperature is 450-550 ℃, and the calcination time is 2-3 h.
4. The process for preparing a MOFs derivative denitration catalyst according to claim 1, wherein the calcination gas in step (2) is CO and/or N2。
5. The process for the preparation of a MOFs derivative denitration catalyst according to claim 4, wherein said CO and N are2The volume ratio of (A) to (B) is 0.5:1-2: 1.
6. The process for the preparation of a MOFs derivative denitration catalyst according to claim 4, wherein said CO and N are2In a volume ratio of 0.95:1 to 1.05: 1.
7. The MOFs derivative denitration catalyst prepared by the preparation method according to any one of claims 1 to 6, wherein the catalyst is FeO having an octahedral structurex/C。
8. The MOFs derivative denitration catalyst according to claim 7, wherein the specific surface area of the catalyst is 260-300m2(ii)/g, the average pore diameter is 6.5-8.5 nm.
9. The MOFs derivative denitration catalyst according to claim 7, wherein the catalyst surface is exposed to high activity (111) crystal face.
10. Use of the MOFs derivative denitration catalyst according to any one of claims 7 to 9 for denitration.
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| CN108940289A (en) * | 2018-08-17 | 2018-12-07 | 太原理工大学 | A kind of ferronickel based composite oxide catalyst and its preparation method and application |
| CN113262779A (en) * | 2021-05-31 | 2021-08-17 | 河北工业大学 | Preparation method and application of low-temperature SCR denitration catalyst with crystal face effect |
| CN113368865A (en) * | 2021-06-08 | 2021-09-10 | 中国科学院山西煤炭化学研究所 | Denitration catalyst, preparation method thereof and waste gas denitration method |
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| CN108940289A (en) * | 2018-08-17 | 2018-12-07 | 太原理工大学 | A kind of ferronickel based composite oxide catalyst and its preparation method and application |
| CN113262779A (en) * | 2021-05-31 | 2021-08-17 | 河北工业大学 | Preparation method and application of low-temperature SCR denitration catalyst with crystal face effect |
| CN113368865A (en) * | 2021-06-08 | 2021-09-10 | 中国科学院山西煤炭化学研究所 | Denitration catalyst, preparation method thereof and waste gas denitration method |
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| CN114505066A (en) * | 2022-01-27 | 2022-05-17 | 中国建筑材料科学研究总院有限公司 | Denitration catalyst, preparation method thereof and denitration method |
| CN114505066B (en) * | 2022-01-27 | 2023-09-29 | 中国建筑材料科学研究总院有限公司 | Denitration catalyst, preparation method thereof and denitration method |
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