CN113398921A - TiO 22Preparation of loaded manganese cerium oxide and application of loaded manganese cerium oxide in medium-temperature SCR denitration based on propylene reduction - Google Patents
TiO 22Preparation of loaded manganese cerium oxide and application of loaded manganese cerium oxide in medium-temperature SCR denitration based on propylene reduction Download PDFInfo
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- LQWKWJWJCDXKLK-UHFFFAOYSA-N cerium(3+) manganese(2+) oxygen(2-) Chemical compound [O--].[Mn++].[Ce+3] LQWKWJWJCDXKLK-UHFFFAOYSA-N 0.000 title claims abstract description 32
- 125000004805 propylene group Chemical group [H]C([H])([H])C([H])([*:1])C([H])([H])[*:2] 0.000 title claims abstract description 21
- QQONPFPTGQHPMA-UHFFFAOYSA-N propylene Natural products CC=C QQONPFPTGQHPMA-UHFFFAOYSA-N 0.000 title claims abstract description 13
- 230000009467 reduction Effects 0.000 title abstract description 7
- 239000003054 catalyst Substances 0.000 claims abstract description 74
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N titanium dioxide Inorganic materials O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims abstract description 22
- 238000000034 method Methods 0.000 claims abstract description 21
- 238000002360 preparation method Methods 0.000 claims abstract description 20
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 claims abstract description 18
- 239000003638 chemical reducing agent Substances 0.000 claims abstract description 17
- 238000011068 loading method Methods 0.000 claims abstract description 11
- 239000007789 gas Substances 0.000 claims description 23
- 239000007787 solid Substances 0.000 claims description 20
- 239000003546 flue gas Substances 0.000 claims description 18
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims description 17
- 239000011572 manganese Substances 0.000 claims description 13
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 13
- 238000001354 calcination Methods 0.000 claims description 10
- 238000001035 drying Methods 0.000 claims description 8
- 238000010438 heat treatment Methods 0.000 claims description 8
- 238000010926 purge Methods 0.000 claims description 8
- 238000003756 stirring Methods 0.000 claims description 7
- 229910001868 water Inorganic materials 0.000 claims description 7
- 239000008367 deionised water Substances 0.000 claims description 6
- 229910021641 deionized water Inorganic materials 0.000 claims description 6
- 238000000227 grinding Methods 0.000 claims description 6
- 239000000843 powder Substances 0.000 claims description 6
- 239000000725 suspension Substances 0.000 claims description 6
- 239000012159 carrier gas Substances 0.000 claims description 5
- 238000009826 distribution Methods 0.000 claims description 4
- 238000012216 screening Methods 0.000 claims description 4
- QQZMWMKOWKGPQY-UHFFFAOYSA-N cerium(3+);trinitrate;hexahydrate Chemical compound O.O.O.O.O.O.[Ce+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O QQZMWMKOWKGPQY-UHFFFAOYSA-N 0.000 claims description 3
- ALIMWUQMDCBYFM-UHFFFAOYSA-N manganese(2+);dinitrate;tetrahydrate Chemical compound O.O.O.O.[Mn+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O ALIMWUQMDCBYFM-UHFFFAOYSA-N 0.000 claims description 3
- 238000001704 evaporation Methods 0.000 claims description 2
- 238000007873 sieving Methods 0.000 claims description 2
- 238000006243 chemical reaction Methods 0.000 abstract description 28
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 abstract description 25
- 230000000694 effects Effects 0.000 abstract description 13
- 229910021529 ammonia Inorganic materials 0.000 abstract description 10
- 239000004215 Carbon black (E152) Substances 0.000 abstract description 7
- 229930195733 hydrocarbon Natural products 0.000 abstract description 7
- 150000002430 hydrocarbons Chemical class 0.000 abstract description 7
- 230000002779 inactivation Effects 0.000 abstract description 6
- 238000012360 testing method Methods 0.000 abstract description 6
- 229910052723 transition metal Inorganic materials 0.000 abstract description 5
- 150000003624 transition metals Chemical class 0.000 abstract description 5
- 238000011161 development Methods 0.000 abstract description 4
- 229910016978 MnOx Inorganic materials 0.000 abstract 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 abstract 1
- 239000010931 gold Substances 0.000 abstract 1
- 229910052737 gold Inorganic materials 0.000 abstract 1
- 229910052751 metal Inorganic materials 0.000 abstract 1
- 239000002184 metal Substances 0.000 abstract 1
- 229910044991 metal oxide Inorganic materials 0.000 abstract 1
- 150000004706 metal oxides Chemical class 0.000 abstract 1
- 230000007704 transition Effects 0.000 abstract 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 6
- 239000002808 molecular sieve Substances 0.000 description 6
- 238000006722 reduction reaction Methods 0.000 description 6
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 description 6
- 238000005516 engineering process Methods 0.000 description 5
- 230000004048 modification Effects 0.000 description 5
- 238000012986 modification Methods 0.000 description 5
- 230000008569 process Effects 0.000 description 5
- 239000002245 particle Substances 0.000 description 4
- 238000011156 evaluation Methods 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 3
- 229910000510 noble metal Inorganic materials 0.000 description 3
- 150000003863 ammonium salts Chemical class 0.000 description 2
- 238000004523 catalytic cracking Methods 0.000 description 2
- 238000010531 catalytic reduction reaction Methods 0.000 description 2
- 230000006378 damage Effects 0.000 description 2
- 230000009849 deactivation Effects 0.000 description 2
- 230000018109 developmental process Effects 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- 229910000069 nitrogen hydride Inorganic materials 0.000 description 2
- 231100000572 poisoning Toxicity 0.000 description 2
- 230000000607 poisoning effect Effects 0.000 description 2
- 238000006479 redox reaction Methods 0.000 description 2
- 230000008929 regeneration Effects 0.000 description 2
- 238000011069 regeneration method Methods 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 238000001878 scanning electron micrograph Methods 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- 239000002351 wastewater Substances 0.000 description 2
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 238000005299 abrasion Methods 0.000 description 1
- MQRWBMAEBQOWAF-UHFFFAOYSA-N acetic acid;nickel Chemical compound [Ni].CC(O)=O.CC(O)=O MQRWBMAEBQOWAF-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 238000003916 acid precipitation Methods 0.000 description 1
- 238000003915 air pollution Methods 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 239000007809 chemical reaction catalyst Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005485 electric heating Methods 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 239000010881 fly ash Substances 0.000 description 1
- 239000002803 fossil fuel Substances 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 229940071125 manganese acetate Drugs 0.000 description 1
- UOGMEBQRZBEZQT-UHFFFAOYSA-L manganese(2+);diacetate Chemical compound [Mn+2].CC([O-])=O.CC([O-])=O UOGMEBQRZBEZQT-UHFFFAOYSA-L 0.000 description 1
- 229940078494 nickel acetate Drugs 0.000 description 1
- -1 nitrogen-containing organic compound Chemical class 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 239000012286 potassium permanganate Substances 0.000 description 1
- 229960001841 potassium permanganate Drugs 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 239000012495 reaction gas Substances 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 229910000314 transition metal oxide Inorganic materials 0.000 description 1
- NWJUARNXABNMDW-UHFFFAOYSA-N tungsten vanadium Chemical compound [W]=[V] NWJUARNXABNMDW-UHFFFAOYSA-N 0.000 description 1
- 229940124024 weight reducing agent Drugs 0.000 description 1
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- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/16—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
- B01J23/32—Manganese, technetium or rhenium
- B01J23/34—Manganese
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- 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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Abstract
The invention discloses a TiO 22The preparation of the loaded manganese cerium oxide and the application of the loaded manganese cerium oxide in medium-temperature SCR denitration based on propylene reduction. Propylene in light hydrocarbon is used as a reducing agent for SCR reaction, transition metal-based metal oxide is used as a catalyst, and CeO is addedxDoped in TiO2Preparing Ce-Ti carrier and loading active component MnOxThe activity of the catalyst in the reaction temperature range of 300-400 ℃ is tested under different active component loading amounts, and the test result shows that the independently developed transition gold using propylene as a reducing agentThe denitration efficiency of the metal-based catalyst can reach 70%, the selectivity can reach 100%, and the concentration of NO after reaction meets the emission standard. The method can avoid the problem of inactivation of a series of catalysts caused by using ammonia as a reducing agent, and the transition metal-based catalyst is cheap, easy to obtain and environment-friendly, so that the development of the light hydrocarbon-SCR transition metal-based catalyst has huge development prospect.
Description
Technical Field
The invention relates to the technical field of catalyst preparation, in particular to TiO2The preparation of the loaded manganese cerium oxide and the application of the loaded manganese cerium oxide in medium-temperature SCR denitration based on propylene reduction.
Background
Nitrogen Oxides (NO)x) Is one of the main components of atmospheric pollutants, can cause important pollution such as acid rain, photochemical pollution, haze and the like, and also has serious harm to human health. Fossil fuels burned in the production process of enterprises such as petrochemical plants, power plants and the like can generate a large amount of NOxThe "air pollution prevention and treatment law" issued by 2016 China proposes to treat NOxMore stringent emission requirements: NO of refining enterprise in key area at presentxThe emission standard is 100mg/m3And the future ultra-low emission standard is 50mg/m3Therefore, the emission reduction problem of enterprises is imminent.
NO in industrial catalytic cracking regeneration flue gas at present stagexIn the denitration means, a Selective Catalytic Reduction (SCR) method is a post-treatment technology for flue gas purification, is one of the most common and mature technologies for industrial catalytic cracking regeneration flue gas denitration, and is one of the technologies with the highest denitration efficiency, and in the traditional industrial SCR denitration technology, the selected reducing agent is generally ammonia gas. Ammonia gas as a reducing agent is difficult to store and expensive in the engineering application process, and can overcome the defects of ammonia escape and the like caused by a large amount of ammonia spraying; in addition to this, NH3The vanadium-tungsten catalyst used in the SCR system is susceptible to fly ash and sulfur poisoning to form ammonium salt crystals at the temperature of 300-400 ℃ with the highest reaction activity. And NH3The SCR system adopts a molecular sieve catalyst, so that the phenomena of molecular sieve framework collapse and catalyst inactivation are easily caused at low temperature, most procedures in the preparation process of the catalyst are complex, the cost is high, and a large amount of ammonia wastewater is generated.
The research on the SCR denitration reaction mainly aims at finding a more energy-saving and efficient reducing agent, improving the activity of the catalyst to prolong the service life and reduce the preparation cost. Although the specific surface area and the cost of the carrier of the activated carbon-based catalyst are low, the activated carbon is easy to sinter when meeting high temperature, so that the catalyst is inactivated, and therefore, the temperature window is narrow and the applicability is not high; the molecular sieve catalyst has higher activity, higher cost and poor hydrothermal stability, and the catalyst is easy to lose activity due to the collapse of a framework; the noble metal-based catalyst has high activity and good adaptability, but has high cost and is not suitable for industrial application.
At present, research on the SCR system by taking light hydrocarbon as a reducing agent is more and more, and compared with ammonia gas, tail gas generated after light hydrocarbon participates in denitration reaction is CO2And H2O, no other pollution gas is generated, and the light hydrocarbon has wide source and low price, thereby effectively reducing the cost. In the SCR system using light hydrocarbon as reducing agent, the used catalyst is mostly molecular sieve and noble metal catalyst.
Selective Catalytic Reduction (SCR) technology for removing NO from flue gas by using reducing agent C3H6Reduction of NO to N by moderately unsaturated bonds2，C3H6With NO and O in the flue gas2Under the condition of NO catalyst, the oxidation-reduction reaction is difficult to occur, the reduction effect on NO is extremely unobvious, and the reducing agent can reduce NO in the flue gas into N by utilizing the catalyst in the flue gas atmosphere2. The catalyst has the reaction promoting effect mainly embodied in that the active components on the catalyst provide acid sites which can adsorb reaction gas, so that the oxidation-reduction reaction is smoothly carried out.
C3H6The equation for the SCR reaction is as follows:
C3H6+2NO+3.502＝N2+3CO2+1.5H2O
the removal efficiency of NO in the evaluation reaction is as follows:
the denitration efficiency of the catalyst was evaluated by comparing the NO concentrations before and after the reaction. In addition, to N2The selectivity of (A) is also an important index for evaluating the effect of the catalyst, and the calculation formula is as follows:
chinese patent CN112774688A discloses a method for preparing a nano-scale manganese-based oxide catalyst by using ammonia gas as a reducing agent and potassium permanganate, nickel acetate and manganese acetate at normal pressure, 100-200 ℃ and 30000h-1Under the condition of space velocity, the NO conversion rate can reach more than 99 percent. The method effectively improves the activity of the catalyst and reduces the manufacturing cost. However, ammonia gas is difficult to store and transport as a reducing agent, ammonia escape easily occurs in the SCR application process and causes catalyst poisoning, the manufacturing cost of the traditional catalyst such as a molecular sieve or a noble metal is high, the molecular sieve catalyst or the catalyst prepared by taking activated carbon as a carrier has serious inactivation, the structure is unstable, and the service life is short. There is a great need to develop new catalysts for denitration.
Disclosure of Invention
Aiming at the problems that ammonia escape generated in industrial application cannot be solved due to the fact that ammonia is selected as a reducing agent in the prior art, and extra pollution is caused due to ammonia wastewater generated in the preparation process of the selected catalyst, the invention provides TiO2The preparation of the loaded manganese cerium oxide and the application of the loaded manganese cerium oxide in medium-temperature SCR denitration based on propylene reduction have the advantages that the denitration is environment-friendly, no waste liquid and the like are generated in the preparation process of the catalyst, and the energy conservation and the environmental protection are realized. In addition, the process simultaneously solves NOxAnd the pollution problem of light hydrocarbon gas, and the resource utilization of propylene is realized.
step 1, taking 15.5g-23.3g cerous nitrate hexahydrate solid, dissolving in 200ml deionized water, adding 35.5g-26.7g nano TiO2Placing the beaker filled with the suspension into a water bath kettle, stirring and heating until the solution is evaporated to dryness to obtain a solid;
step 3, grinding and screening the dried solid to obtain powder of 80-120 meshes, and calcining the powder in a muffle furnace for 5 hours to obtain the Ce-Ti carrier;
step 6, grinding the dried solid, sieving the ground solid with a sieve of 80-120 meshes, transferring the powder into a muffle furnace, and calcining for 5 hours to obtain fresh TiO2And loading manganese cerium oxide.
The improvement is that the mass ratio of Ce element in the Ce-Ti carrier in the step 3 is 10-15%.
As a modification, the temperature of calcination in step 3 is 450 ℃.
As a modification, the TiO described in step 62The mass ratio of Mn element in the loaded manganese cerium oxide is 5-10%.
As a modification, the temperature of calcination in step 6 was 350 ℃.
TiO prepared as described above2Application of loaded manganese cerium oxide in medium-temperature SCR denitration by taking propylene as reducing agent and nano-scale TiO2The loaded manganese cerium oxide is used as a catalyst for SCR denitration, and the method comprises the following specific steps:
first, 10.5ml TiO is taken2Loading manganese cerium oxide in reactor, introducing N2Purging for 10min, programming the temperature to 300 ℃ at the speed of 10 ℃/min, and continuing purging for 30 min;
second, the gas is passed to a bypass for simulationThe gas is distributed, the total flow is 1400ml/min, and the airspeed is 8000h-1In which O is2Concentration of 3% NO and C3H6The concentration ratio of (1): 1-2.1, carrier gas is N2Introducing gas into a flue gas analyzer to record original data;
and step three, introducing the prepared gas into a reactor, keeping the temperature at 300 ℃ for 30min, carrying out programmed heating on the reactor to 300-400 ℃, wherein the heating rate is 5 ℃/min, keeping the temperature for 30min every 25 ℃, recording data, and the data acquisition points are 300 ℃, 325 ℃, 350 ℃, 375 ℃ and 400 ℃.
As a modification, the reactor is a fixed bed reactor.
Has the advantages that:
compared with the prior art, the method uses the propylene as the reducing agent, so that a series of problems of catalyst inactivation and the like caused by ammonia escape and ammonium salt crystallization in an ammonia SCR system are avoided; meanwhile, the invention uses the transition metal-based catalyst which is cheap and easy to obtain and is environment-friendly. At 300 ℃ the inlet concentration of NO is 300mg/m3、O2Under the working condition that the concentration is 3 percent, using propylene as a reducing agent and TiO2The denitration efficiency of the medium-temperature SCR denitration catalyst loaded with the manganese cerium oxide can reach 70%, the selectivity can reach 100%, and the concentration of NO after reaction meets the emission standard. Therefore, the development of the light hydrocarbon-SCR transition metal-based catalyst has huge development prospect. The concrete expression is as follows:
(1) the propylene is used as the catalyst, so that the pollution problem of light hydrocarbon can be solved, and no pollution gas and waste can be generated in the preparation process of the catalyst and the application process of the SCR system;
(2) the transition metal oxide is used as a catalyst carrier, so that the preparation cost of the catalyst is greatly reduced, the preparation process is simpler, the preparation cost is lower, and the catalyst is suitable for the existing industrial application temperature zone;
(3) the catalyst developed by the method has a stable structure, high activity, denitration efficiency of 70 percent and selectivity of 100 percent, and no deactivation phenomenon is found after long-time reaction; the highest reaction temperature zone is 300-400 ℃, the method is suitable for the flue gas temperature of the existing industrial SCR application system, and the method can be directly used when the concentration of NO reaches the emission standard after the denitration of the tail gas components of the refinery plant.
Drawings
FIG. 1 is a schematic representation of TiO preparation in example 12A flow chart of loading manganese cerium oxide;
FIG. 2 shows Mn5-Ce0.1/TiO2Schematic structural diagram of catalyst evaluation system, wherein, 1-N2Tank, 2-O2Canister, 3-NO canister, 4-C3H6A tank, 5-a pressure gauge, 6-an electric heating furnace, 7-a filter element, 8-a flue gas analyzer and 9-a bypass;
FIG. 3 shows Mn5-Ce0.1/TiO2Activity of the catalyst as a function of temperature;
FIG. 4 shows Mn5-Ce0.1/TiO2A plot of catalyst selectivity versus temperature;
FIG. 5 shows the inlet C3H6The effect of the ratio to NO on NO conversion;
FIG. 6 shows fresh Mn5-Ce0.1/TiO2SEM image after 5000 times of catalyst magnification;
FIG. 7 shows Mn after reaction5-Ce0.1/TiO2SEM image after 5000 times magnification of catalyst.
Detailed Description
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference herein for the purpose of disclosing and describing the methods and/or materials associated with the documents. In case of conflict with any incorporated document, the present specification will control.
Example 1
Adopting the process shown in FIG. 1, a TiO2The preparation method of the loaded manganese cerium oxide comprises the following steps:
(1) 15.5g of cerous nitrate hexahydrate solid is dissolved in 200ml of deionized water, 35.5g of nano TiO is added2Placing the beaker filled with the suspension into a water bath kettle, stirring and heating until the solution is evaporated to dryness to obtain a solid;
(2) putting the solid evaporated in the step (1) into a drying box, and drying for 12h at 110 ℃;
(3) grinding the dried solid in the step (2), screening particles of 80-120 meshes, and calcining the particles in a muffle furnace at 450 ℃ for 5 hours to obtain a Ce-Ti carrier;
(4) dissolving 11.4g of manganese nitrate tetrahydrate in 200ml of deionized water, adding 38.6g of Ce-Ti carrier, uniformly stirring, putting the beaker filled with the suspension into a water bath kettle, stirring and heating until the solution is evaporated to dryness;
(5) putting the solid evaporated in the step (4) into a drying box, and drying for 12h at 110 ℃;
(6) grinding the solid dried in the step (5), screening out particles of 80-120 meshes, putting the particles into a muffle furnace, and calcining for 5 hours at 350 ℃, namely, fresh TiO2Supported manganese cerium oxide, noted Mn5-Ce0.1/TiO2A catalyst.
Example 2
The catalyst is tested by using the evaluation system shown in fig. 2, and the specific connection mode can be referred to fig. 2, and all the connection modes are conventional connection modes. The specific test conditions and steps are as follows:
(1) adding 10.5ml of Mn5-Ce0.1/TiO2The catalyst is placed in a reactor and is introduced with N2Purging for 10min, and continuing purging for 30min after the temperature is programmed to 300 ℃ at a speed of 10 ℃/min;
(2) the gas is led to a bypass to simulate the distribution of the flue gas, the total flow is 1400ml/min, and the space velocity is 8000h-1In which O is2Concentration of 3%, NO concentration of 150ppm, C3H6Concentration is 150ppm, carrier gas is N2Introducing gas into a flue gas analyzer to record original data;
(3) introducing the prepared gas into a reactor, keeping the temperature for 30min after the data are stable at 300 ℃ and the like, carrying out temperature programming on the reactor to 400 ℃ at 300 ℃, wherein the temperature rise rate is 5 ℃/min, keeping the temperature for 30min every 25 ℃, recording the data, and the data acquisition points are 300 ℃, 325 ℃, 350 ℃, 375 ℃ and 400 ℃.
Analyzing the data after the activity test, and obtaining the resultAs shown in FIG. 3, in the temperature region of 300-400 ℃, the denitration efficiency of the catalyst is significantly reduced along with the increase of the temperature, the highest denitration efficiency can reach 68% at 300 ℃, and the lowest denitration efficiency is 35% at 400 ℃, for the catalyst C prepared by the method of the invention3H6: the NO-1 is in a flue gas temperature range, and the reaction temperature is most preferably 300 ℃. After the reaction for 5 hours under the conditions, the reaction activity of the catalyst is unchanged, the denitration efficiency is still 68%, and the catalyst is recorded as a catalyst after the reaction, wherein the catalyst does not show deactivation phenomenon.
Example 3
Adjusting the gas distribution concentration of the reducing agent under the condition of selecting the optimal reaction temperature, and testing C3H6Mn in different proportions from NO5-Ce0.1/TiO2The denitration efficiency of the catalyst is specifically tested under the following conditions and steps:
(1) 10.5ml of TiO2Loading manganese cerium oxide in reactor, introducing N2Purging for 10min, and continuing purging for 30min after the temperature is programmed to 300 ℃ at a speed of 10 ℃/min.
(2) The gas is led to a bypass to simulate the distribution of the flue gas, the total flow is 1400ml/min, and the space velocity is 8000h-1In which O is2Concentration of 3%, NO concentration of 150ppm, C3H6Concentration is 150ppm, carrier gas is N2And introducing the gas into a flue gas analyzer to record original data.
(3) Introducing the prepared gas into a reactor, keeping for 30min at 300 deg.C until the data is stable, and recording the concentration C at inlet3H6: the outlet gas concentration at NO 1; keeping the total flow and space velocity constant, and increasing C under the condition that the NO concentration is 150ppm3H6Concentration such that the concentration at the inlet C3H6: and keeping the NO 1.1 for 20min after the data are stabilized, and recording the gas concentration at the outlet. Then C3H6: recording outlet gas concentration data after the data are stabilized for 30min every time the NO ratio is increased by 0.1, and testing C3H6: denitration efficiency of the NO ═ 1-2.1 internal catalyst.
As shown in FIG. 4, denitration efficiency C of the catalyst3H6: increase in NO ratio, at C3H6: when NO is 1, the denitration efficiency is 68%, at C3H6: NO 2 or C3H6: when NO is 2.1, the denitration efficiency can reach 72 percent, and when C is used, the denitration efficiency can reach C3H6: when NO is 2, saturation is achieved, and the denitration efficiency does not increase with the increase of the ratio.
TiO developed for this patent2Supported manganese cerium oxide, C3H6When the concentration ratio of the nitrogen-containing organic compound to NO is 2, the denitration efficiency is highest and the denitration is economical. As shown in FIG. 5, the conversion of NO to N is shown2The selectivity and the temperature of the catalyst are in a temperature range of 300-400 ℃, and NO is completely converted into N2According to N2Formula for calculating selectivity, N of the catalyst2The selectivity was 100% and NO was completely converted to the desired product.
Example 4
For Mn5-Ce0.1/TiO2The catalyst is analyzed by a scanning electron microscope, and the influence of the reaction on the catalyst is known through the shapes of the catalyst before and after the reaction.
(1) As shown in fig. 6, which is a graph of fresh catalyst after SEM magnification of 5000 times, it can be seen from the graph that the catalyst surface before reaction is smooth, the carrier has better loading of active component, the active component has more loading, the dispersion degree is higher, the pores are larger, and therefore the catalytic effect is better.
(2) The post-reaction catalyst, as shown in figure 7, was run under the following conditions: the total flow rate is 1400ml/min, and the space velocity is 8000h-1In which O is2Concentration of 3%, NO concentration of 150ppm, C3H6Concentration is 150ppm, carrier gas is N2And reacting at 300 ℃ for 5 h. As can be seen from the figure, the surface of the catalyst is still smooth and has no obvious abrasion and damage after 5h of reaction, the loading and dispersion degree of the active components are very high, and the integral structure of the catalyst is basically unchanged, thus proving that the catalyst has no inactivation and has stable structure.
Mn prepared by the invention5-Ce0.1/TiO2The catalyst has a stable structure, the denitration efficiency can reach about 70%, the selectivity can reach 100%, and no inactivation phenomenon is found after long-time reaction; the highest reaction temperature is 300 ℃ and 400 ℃, and the method is suitable for the existing industryThe SCR application system flue gas temperature reaches the emission standard according to the NO concentration after the denitration of the tail gas components of the refinery, and can be directly used.
The above description is only a preferred embodiment of the present invention, and the scope of the present invention is not limited thereto, and any simple modifications or equivalent substitutions of the technical solutions that can be obviously obtained by those skilled in the art within the technical scope of the present invention are within the scope of the present invention.
Claims (7)
1. TiO 22The preparation method of the loaded manganese cerium oxide is characterized by comprising the following steps:
step 1, taking 15.5g-23.3g cerous nitrate hexahydrate solid, dissolving in 200ml deionized water, adding 35.5g-26.7g nano TiO2Placing the beaker filled with the suspension into a water bath kettle, stirring and heating until the solution is evaporated to dryness to obtain a solid;
step 2, drying the dried solid at 110 ℃ for 12 h;
step 3, grinding and screening the dried solid to obtain powder of 80-120 meshes, and calcining the powder in a muffle furnace for 5 hours to obtain the Ce-Ti carrier;
step 4, dissolving 11.4g-22.8g of manganese nitrate tetrahydrate in 200ml of deionized water, adding 38.6g-27.2g of Ce-Ti carrier, stirring, and evaporating the suspension in a beaker water bath until the solution is evaporated to dryness;
step 5, putting the dried solid into a drying box to be dried for 12 hours at the temperature of 110 ℃;
step 6, grinding the dried solid, sieving the ground solid with a sieve of 80-120 meshes, transferring the powder into a muffle furnace, and calcining for 5 hours to obtain fresh TiO2And loading manganese cerium oxide.
2. The TiO of claim 12The preparation method of the loaded manganese cerium oxide is characterized in that the mass ratio of Ce element in the Ce-Ti carrier in the step 3 is 10-15%.
3. The TiO of claim 12Preparation of supported manganese cerium oxide characterized by calcination in step 3The temperature was 450 ℃.
4. The TiO of claim 12The preparation of the loaded manganese cerium oxide is characterized in that the TiO in the step 62The mass ratio of Mn element in the loaded manganese cerium oxide is 5-10%.
5. The TiO of claim 12The preparation method of the loaded manganese cerium oxide is characterized in that the calcining temperature in the step 6 is 350 ℃.
6. TiO prepared on the basis of claim 12The application of the loaded manganese cerium oxide in medium-temperature SCR denitration is characterized in that propylene is used as a reducing agent, and nano-scale TiO is used2The loaded manganese cerium oxide is used as a catalyst for SCR denitration, and the method comprises the following specific steps:
first, 10.5ml TiO is taken2Loading manganese cerium oxide in reactor, introducing N2Purging for 10min, programming the temperature to 300 ℃ at the speed of 10 ℃/min, and continuing purging for 30 min;
secondly, the gas is led to a bypass to simulate the distribution of the flue gas, the total flow is 1400ml/min, and the airspeed is 8000h-1In which O is2Concentration of 3% NO and C3H6The concentration ratio of (1): 1-2.1, carrier gas is N2Introducing gas into a flue gas analyzer to record original data;
and step three, introducing the prepared gas into a reactor, keeping the temperature at 300 ℃ for 30min, carrying out programmed heating on the reactor to 300-400 ℃, wherein the heating rate is 5 ℃/min, keeping the temperature for 30min every 25 ℃, recording data, and the data acquisition points are 300 ℃, 325 ℃, 350 ℃, 375 ℃ and 400 ℃.
7. Use according to claim 6, wherein the reactor is a fixed bed reactor.
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