WO2007081084A1 - Catalyst for the removal of nitrogen oxides with reducing agent and its preparation method - Google Patents
Catalyst for the removal of nitrogen oxides with reducing agent and its preparation method Download PDFInfo
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- WO2007081084A1 WO2007081084A1 PCT/KR2006/004802 KR2006004802W WO2007081084A1 WO 2007081084 A1 WO2007081084 A1 WO 2007081084A1 KR 2006004802 W KR2006004802 W KR 2006004802W WO 2007081084 A1 WO2007081084 A1 WO 2007081084A1
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- Prior art keywords
- catalyst
- silver
- nitrogen oxides
- reducing agent
- impregnated
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- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 title claims abstract description 101
- 239000003054 catalyst Substances 0.000 title claims abstract description 69
- 238000002360 preparation method Methods 0.000 title claims abstract description 20
- 239000003638 chemical reducing agent Substances 0.000 title claims description 19
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims abstract description 49
- 229910052709 silver Inorganic materials 0.000 claims abstract description 49
- 239000004332 silver Substances 0.000 claims abstract description 49
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims abstract description 35
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 claims abstract description 22
- 239000000460 chlorine Substances 0.000 claims abstract description 22
- 229910052801 chlorine Inorganic materials 0.000 claims abstract description 22
- 239000000758 substrate Substances 0.000 claims description 29
- SQGYOTSLMSWVJD-UHFFFAOYSA-N silver(1+) nitrate Chemical compound [Ag+].[O-]N(=O)=O SQGYOTSLMSWVJD-UHFFFAOYSA-N 0.000 claims description 23
- 238000001035 drying Methods 0.000 claims description 20
- 238000001354 calcination Methods 0.000 claims description 18
- 239000011248 coating agent Substances 0.000 claims description 15
- 238000000576 coating method Methods 0.000 claims description 15
- 230000003197 catalytic effect Effects 0.000 claims description 12
- 239000002002 slurry Substances 0.000 claims description 8
- 239000000203 mixture Substances 0.000 claims description 7
- 229910001961 silver nitrate Inorganic materials 0.000 claims description 7
- 229910052878 cordierite Inorganic materials 0.000 claims description 6
- JSKIRARMQDRGJZ-UHFFFAOYSA-N dimagnesium dioxido-bis[(1-oxido-3-oxo-2,4,6,8,9-pentaoxa-1,3-disila-5,7-dialuminabicyclo[3.3.1]nonan-7-yl)oxy]silane Chemical compound [Mg++].[Mg++].[O-][Si]([O-])(O[Al]1O[Al]2O[Si](=O)O[Si]([O-])(O1)O2)O[Al]1O[Al]2O[Si](=O)O[Si]([O-])(O1)O2 JSKIRARMQDRGJZ-UHFFFAOYSA-N 0.000 claims description 6
- 238000000498 ball milling Methods 0.000 claims description 4
- 239000012153 distilled water Substances 0.000 claims description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 4
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 claims description 3
- 229910010271 silicon carbide Inorganic materials 0.000 claims description 3
- HKZLPVFGJNLROG-UHFFFAOYSA-M silver monochloride Chemical group [Cl-].[Ag+] HKZLPVFGJNLROG-UHFFFAOYSA-M 0.000 claims description 3
- YPNVIBVEFVRZPJ-UHFFFAOYSA-L silver sulfate Chemical compound [Ag+].[Ag+].[O-]S([O-])(=O)=O YPNVIBVEFVRZPJ-UHFFFAOYSA-L 0.000 claims description 3
- 239000013078 crystal Substances 0.000 claims description 2
- 239000002243 precursor Substances 0.000 claims description 2
- 239000007789 gas Substances 0.000 abstract description 15
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 abstract description 6
- 239000004215 Carbon black (E152) Substances 0.000 abstract description 4
- 229930195733 hydrocarbon Natural products 0.000 abstract description 4
- 150000002430 hydrocarbons Chemical class 0.000 abstract description 4
- 239000007788 liquid Substances 0.000 abstract description 4
- 239000000446 fuel Substances 0.000 abstract description 3
- 229910052757 nitrogen Inorganic materials 0.000 abstract description 3
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 abstract 1
- 239000000919 ceramic Substances 0.000 abstract 1
- 229910017052 cobalt Inorganic materials 0.000 abstract 1
- 239000010941 cobalt Substances 0.000 abstract 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 abstract 1
- 229910052802 copper Inorganic materials 0.000 abstract 1
- 239000010949 copper Substances 0.000 abstract 1
- 230000000052 comparative effect Effects 0.000 description 8
- 230000000694 effects Effects 0.000 description 8
- 238000006243 chemical reaction Methods 0.000 description 6
- 238000010438 heat treatment Methods 0.000 description 6
- 238000000034 method Methods 0.000 description 6
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 3
- 229910021536 Zeolite Inorganic materials 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 3
- 238000011156 evaluation Methods 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- 239000010457 zeolite Substances 0.000 description 3
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 description 2
- 230000005484 gravity Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- QQONPFPTGQHPMA-UHFFFAOYSA-N propylene Natural products CC=C QQONPFPTGQHPMA-UHFFFAOYSA-N 0.000 description 2
- 125000004805 propylene group Chemical group [H]C([H])([H])C([H])([*:1])C([H])([H])[*:2] 0.000 description 2
- 238000004566 IR spectroscopy Methods 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000001294 propane Substances 0.000 description 1
- 239000000376 reactant Substances 0.000 description 1
- 239000012495 reaction gas Substances 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 229940100890 silver compound Drugs 0.000 description 1
- 150000003379 silver compounds Chemical class 0.000 description 1
- 230000003381 solubilizing effect Effects 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
Classifications
-
- 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
- B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
- B01J23/48—Silver or gold
- B01J23/50—Silver
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
- B27B—SAWS FOR WOOD OR SIMILAR MATERIAL; COMPONENTS OR ACCESSORIES THEREFOR
- B27B17/00—Chain saws; Equipment therefor
- B27B17/08—Drives or gearings; Devices for swivelling or tilting the chain saw
- B27B17/083—Devices for arresting movement of the saw chain
-
- 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
- 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
- B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
- B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
- B01D53/9404—Removing only nitrogen compounds
- B01D53/9409—Nitrogen oxides
- B01D53/9413—Processes characterised by a specific catalyst
- B01D53/9418—Processes characterised by a specific catalyst for removing nitrogen oxides by selective catalytic reduction [SCR] using a reducing agent in a lean exhaust gas
-
- 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
- B01J35/00—Catalysts, in general, characterised by their form or physical properties
- B01J35/50—Catalysts, in general, characterised by their form or physical properties characterised by their shape or configuration
- B01J35/56—Foraminous structures having flow-through passages or channels, e.g. grids or three-dimensional monoliths
-
- 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
- B01J37/0201—Impregnation
-
- 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
- B01J37/024—Multiple impregnation or coating
- B01J37/0242—Coating followed by impregnation
-
- 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
- B01J37/22—Halogenating
- B01J37/24—Chlorinating
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2255/00—Catalysts
- B01D2255/10—Noble metals or compounds thereof
- B01D2255/104—Silver
Definitions
- the present invention relates to a preparation method of catalyst for removing nitrogen oxides comprised in the exhaust gas of fixed and mobile source burning gas and liquid state of hydrocarbon as a fuel. More particularly, the present invention relates to the preparation method of catalyst applied to the device reducing nitrogen oxides to nitrogen by reducing agent and catalyst with the processes of : i) setting the catalyst in a path of exhaust gas and ii) spraying the reducing agent to inlet of catalyst.
- the present invention provides the catalyst for removing nitrogen oxides comprised in the exhaust gas of fixed and mobile source burning gas and liquid state of hydrocarbon and its preparation method.
- the present invention provides the catalyst having high activity of reducing nitrogen oxides to nitrogen and wide available temperature range and its preparation method.
- an object of the present invention is to provide the catalyst for reducing nitrogen oxides by impregnating alumina carrier with silver (Ag) and chlorine.
- the present invention provides a novel catalyst for reducing nitrogen oxides by impregnating alumina carrier with silver catalytic component and chlorine. Another object of the present invention is to provide a novel catalyst for reducing nitrogen oxides more effectively.
- the present invention relates to the catalyst for removing nitrogen oxides comprised in the exhaust gas of fixed and mobile source burning gas and liquid state of hydrocarbon as a fuel and its preparation method. More particularly, the present invention relates to the catalyst for reducing nitrogen oxides with reducing agent and its preparation method, in which the catalyst is comprised of the support coated with the catalyst prepared by impregnating the carrier with silver and chlorine component .
- the catalyst for reducing nitrogen oxides means the catalyst prepared by impregnating the powder typed carrier, specially, alumina carrier with silver and chlorine component.
- alumina carrier having amorphous, gamma, theta or eta typed crystal structure. It can be used by coating the support such as honeycomb substrate or silicon substrate, preferably cordierite honeycomb substrate with said alumina carrier.
- Reduced silver (Ag) silver chloride (AgCl) , silver nitrate (AgNO 3 ) , silver sulfate (Ag 2 SO 4 ) or its mixture can be used for the silver material according to the present invention. And, it is preferable to apply 0.1 to 10 wt% of silver per weight of alumina carrier. If the amount of silver is less than 0.1 wt%, the efficiency of the catalyst may be decrease considerably because the absolute quantity of silver having catalytic activity decreases. If the amount of silver exceeds 10 wt%, the efficiency of the catalyst may be decrease considerably because silver remains an unfavorable metal for the reaction.
- the amount of impregnated chlorine component is not limited.
- the catalyst is prepared by the steps of : i) immersing the alumina carrier impregnated with silver component or the substrate coated with said alumina carrier in aqueous HCl solution controlled at pH 3 ⁇ 6.5 and ii) calcinating said carrier or said substrate at 450 ⁇ 600 0 C.
- Said aqueous HCl solution can be used regardless of its pH range, but if the pH of aqueous HCl solution is controlled at pH 3 ⁇ 6.5, the efficiency of the catalyst for reducing nitrogen oxides is more excellent. Also, if the calcination is performed at said temperature range, the activity of the catalyst is more excellent.
- the alumina carrier impregnated with chlorine and silver component is wash-coated to the substrate again.
- the preparation method of the catalyst for reducing nitrogen oxides according to the present invention is described in more detail.
- the catalyst for reducing nitrogen oxides according to the present invention is prepared by the steps of : i) preparing the uniform alumina slurry by adding the alumina to deionized distilled water and ball-milling, ii) drying or drying and calcination after coating silicon carbide or cordierite honeycomb substrate with said slurry, iii) drying at room temperature or drying and calcination after immersing said dried or calcinated honeycomb substrate in silver precursor solution and iv) drying and calcination after coating by immersing said substrate impregnated with silver component in aqueous HCl solution.
- the preparation method of the catalyst for reducing nitrogen oxides comprises the steps of : i) preparing the uniform alumina slurry by adding the alumina to deionized distilled water and wet ball- milling, ii) drying at room temperature, if necessary, drying and calcination in a furnace after coating silicon carbide or cordierite honeycomb substrate with said slurry, iii) drying at room temperature, if necessary, drying and calcination in a furnace after immersing said dried or calcinated honeycomb substrate in silver chloride (AgCl) , silver nitrate (AgNO 3 ) , silver sulfate (Ag 2 SO 4 ) or its mixture solution and iv) drying and calcination in a furnace after coating by immersing said substrate impregnated with silver component in aqueous HCl solution controlled at pH 3 ⁇ 6.5 sufficiently.
- said drying and calcination in a furnace are performed by drying at 80 ⁇ 150 0 C for 1 - 5 hours after heating from the room temperature slowly, and then calcination at 450 ⁇ 600 0 C for 1 - 5 hours after heating slowly.
- FIG. 1 shows the NOx conversion of the catalyst according to Example 1 and Comparative Example 1.
- the amount of impregnated silver is 4.0 wt% in FIG. 1 and 7.0 wt% in FIG. 2.
- FIG. 3 shows the NOx conversion of the catalyst according to Example 2 and Comparative Example 2.
- the amount of impregnated silver is 2.0 wt% in FIG. 3, 4.0 wt% in FIG.4 and 6.0 wt% in FIG. 5.
- FIG. 6 shows the NOx conversion of the catalyst according to Example 3 and Comparative Example 3. [Mode for Invention]
- the uniform alumina slurry was prepared by mixing gamma alumina powder (Al-I, surface area : 210 m 2 /g, pore volume : 0.5 cc/g, specific gravity : 0.8 g/cc) , acetic acid and distilled water and grinding the mixture using wet ball- milling for 24 hours.
- the average particle size of the resulting alumina was 2 ⁇ 8 micrometers .
- the cordierite honeycomb (size : 2.5 x 2.5 x 2.5 cm, 400 cpsi) was wash-coated with said alumina slurry, in that the amount of impregnated alumina was 0.244 g/cm 3 . It was dried at 120 0 C for 2 hours after heating from the room temperature to 120 °C (heating rate : 5 °C/min) , and then calcinated at 550 0 C for 3 hours after heating from 120 0 C to 550 °C (heating rate : 5 °C/min) .
- Said calcinated cordierite was immersed in silver nitrate solution, in that the amount of impregnated silver was 4.0 and 7.0 wt% per weight of alumina. It was dried and calcinated in the same condition.
- the substrate impregnated with silver was immersed in aqueous HCl solution diluted to pH 5.0 for 20 seconds, and then dried and calcinated in the same condition. Finally, the substrate impregnated with chlorine and silver was prepared.
- Said prepared honeycomb catalyst was used in the test for reducing nitrogen oxides of the model reaction gas mixture having similar composition with real exhaust gas of motor vehicle.
- the honeycomb catalyst was fixed inside the stainless steel reactor and the thermocouple was set at inlet and outlet of the catalyst. The temperature of the reactor was controlled using the cylindrical furnace carefully.
- Table 1 shows the composition of the exhaust gas injected to said reactor.
- the concentration of exhaust gas (NO, NO 2 , THC, CO and N 2 O) at inlet and outlet of reactor was measured using the quantitation-precision gas analyzer, which adopt chemiluminescent method or infrared spectroscopy, connected to reactor directly. These results were shown in FIG. 1 andFIG. 2.
- Example 1 Except not immersing the substrate in aqueous HCl solution in the preparation of the catalyst, the same processes according to Example 1 were performed. These results were shown in FIG. 1 and FIG. 2 together with the results of Example 1.
- the alumina carrier impregnated with silver and chlorine component according to Example 1 showed a good catalytic characteristics of 80 ⁇ 88% (maximum activity) near 450 0 C and showed an excellent catalytic activity at entire temperature range.
- the alumina carrier impregnated with silver component only according to Comparative Example 1 showed 10 ⁇ 20% lower activity near maximum activity temperature and showed 50% lower catalytic activity at entire temperature range compared to the catalyst of Example 1.
- gamma alumina powder Al-2, surface area : 274 m 2 /g, pore volume : 0.5 cc/g, specific gravity : 0.6 g/cc
- the amount of impregnated silver was 2.0, 4.0 and 6.0 wt% per weight of alumina. Then, it was dried and calcinated in the same condition of wash-coating.
- the substrate impregnated with silver was immersed in aqueous HCl solution diluted to pH 5.5 for 20 seconds, and then dried and calcinated in the same condition of wash- coating. Finally, the substrate impregnated with chlorine and silver was prepared.
- Example 2 Except not immersing the substrate in aqueous HCl solution in the preparation of the catalyst, the same processes according to Example 2 were performed. These results were shown in FIG. 3, FIG. 4 and FIG. 5 together with the results of Example 2.
- the alumina carrier impregnated with silver and chlorine component according to Example 2 showed a high catalytic activity at entire temperature range compared to the alumina carrier impregnated with silver component only according to Comparative Example 2.
- the substrate was immersed in silver nitrate solution, in that the amount of impregnated silver was 2.0 wt% per weight of alumina. Then, it was dried and calcinated in the same condition of wash-coating.
- the substrate impregnated with silver was immersed in aqueous HCl solution diluted to pH 5.5 for 20 seconds, and then dried and calcinated in the same condition of wash- coating. Finally, the substrate impregnated with chlorine and silver was prepared.
- the efficiency evaluation of the catalyst was performed according to Example 1. This result was shown in FIG. 6.
- the substrate coated with alumina was immersed in aqueous HCl solution diluted to pH 5.5 for 20 seconds before in silver nitrate solution, and then dried and calcinated in the same condition of wash-coating.
- the substrate impregnated with chlorine was immersed in silver nitrate solution, in that the amount of impregnated silver was 2.0 wt% per weight of alumina. Then, it was dried and calcinated in the same condition of wash-coating. This result was shown in FIG. 6 together with the result of Example 3.
- the catalyst impregnated with silver and chlorine component according to the present invention showed an excellent catalytic efficiency for reducing nitrogen oxides, and showed a superior catalytic efficiency at wide temperature range compared to the current catalyst .
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Abstract
The present invention relates to a preparation method of catalyst for removing nitrogen oxides comprised in the exhaust gas of fixed and mobile source burning gas and liquid state of hydrocarbon as a fuel. According to the present invention, the efficiency of reducing nitrogen oxide to nitrogen is improved by fixing the chlorine on the surface of the catalyst after impregnating the alumina and some ceramic oxides with silver, copper, cobalt, etc.
Description
CATALYST FOR THE REMOVAL OF NITROGEN OXIDES WITH REDUCING AGENT AND ITS PREPARATION METHOD
[Technical Field]
The present invention relates to a preparation method of catalyst for removing nitrogen oxides comprised in the exhaust gas of fixed and mobile source burning gas and liquid state of hydrocarbon as a fuel. More particularly, the present invention relates to the preparation method of catalyst applied to the device reducing nitrogen oxides to nitrogen by reducing agent and catalyst with the processes of : i) setting the catalyst in a path of exhaust gas and ii) spraying the reducing agent to inlet of catalyst.
[Background Art]
In U. S. Patent No. 5,993,764, the reduction method of nitrogen oxides by using propane and zeolite catalyst as a reducing agent was disclosed. But, it has not used commonly because zeolite catalyst has some problems in maximum activity and durability.
In U. S. Patent No. 5,824,621 and 6,284,211, the reduction method of nitrogen oxides by using ethanol and silver catalyst as a reducing agent was disclosed. It can be used commonly soon because silver catalyst has a high maximum
activity compared to zeolite catalyst and no problem in durability. But, if propylene or gasoline is used as a reducing agent, the maximum activity of silver catalyst is lowered and available temperature range is narrowed.
[Disclosure] [Technical Problem]
The present invention provides the catalyst for removing nitrogen oxides comprised in the exhaust gas of fixed and mobile source burning gas and liquid state of hydrocarbon and its preparation method.
More particularly, the present invention provides the catalyst having high activity of reducing nitrogen oxides to nitrogen and wide available temperature range and its preparation method.
The present inventor found that the removal efficiency of nitrogen oxides can be increased by using the catalyst comprising the catalytic material prepared by impregnating alumina carrier with silver (Ag) and chlorine. Accordingly, an object of the present invention is to provide the catalyst for reducing nitrogen oxides by impregnating alumina carrier with silver (Ag) and chlorine.
The present invention provides a novel catalyst for reducing nitrogen oxides by impregnating alumina carrier with silver catalytic component and chlorine.
Another object of the present invention is to provide a novel catalyst for reducing nitrogen oxides more effectively. [Technical Solution]
The present invention relates to the catalyst for removing nitrogen oxides comprised in the exhaust gas of fixed and mobile source burning gas and liquid state of hydrocarbon as a fuel and its preparation method. More particularly, the present invention relates to the catalyst for reducing nitrogen oxides with reducing agent and its preparation method, in which the catalyst is comprised of the support coated with the catalyst prepared by impregnating the carrier with silver and chlorine component .
Hereinafter, the present invention is described in detail. The catalyst for reducing nitrogen oxides according to the present invention means the catalyst prepared by impregnating the powder typed carrier, specially, alumina carrier with silver and chlorine component. For treating nitrogen oxides easily, it is preferable to use alumina carrier having amorphous, gamma, theta or eta typed crystal structure. It can be used by coating the support such as honeycomb substrate or silicon substrate, preferably cordierite honeycomb substrate with said alumina carrier.
Reduced silver (Ag) , silver chloride (AgCl) , silver nitrate (AgNO3) , silver sulfate (Ag2SO4) or its mixture can be
used for the silver material according to the present invention. And, it is preferable to apply 0.1 to 10 wt% of silver per weight of alumina carrier. If the amount of silver is less than 0.1 wt%, the efficiency of the catalyst may be decrease considerably because the absolute quantity of silver having catalytic activity decreases. If the amount of silver exceeds 10 wt%, the efficiency of the catalyst may be decrease considerably because silver remains an unfavorable metal for the reaction. The amount of impregnated chlorine component is not limited. Further, the catalyst is prepared by the steps of : i) immersing the alumina carrier impregnated with silver component or the substrate coated with said alumina carrier in aqueous HCl solution controlled at pH 3 ~ 6.5 and ii) calcinating said carrier or said substrate at 450 ~ 600 0C. Said aqueous HCl solution can be used regardless of its pH range, but if the pH of aqueous HCl solution is controlled at pH 3 ~ 6.5, the efficiency of the catalyst for reducing nitrogen oxides is more excellent. Also, if the calcination is performed at said temperature range, the activity of the catalyst is more excellent. In the case of calcination after deep-coating the impregnated alumina carrier with aqueous HCl solution, the alumina carrier impregnated with chlorine and silver component is wash-coated to the substrate again.
Hereinafter, the preparation method of the catalyst for reducing nitrogen oxides according to the present invention is described in more detail.
The catalyst for reducing nitrogen oxides according to the present invention is prepared by the steps of : i) preparing the uniform alumina slurry by adding the alumina to deionized distilled water and ball-milling, ii) drying or drying and calcination after coating silicon carbide or cordierite honeycomb substrate with said slurry, iii) drying at room temperature or drying and calcination after immersing said dried or calcinated honeycomb substrate in silver precursor solution and iv) drying and calcination after coating by immersing said substrate impregnated with silver component in aqueous HCl solution. The preparation method of the catalyst for reducing nitrogen oxides according to the present invention comprises the steps of : i) preparing the uniform alumina slurry by adding the alumina to deionized distilled water and wet ball- milling, ii) drying at room temperature, if necessary, drying and calcination in a furnace after coating silicon carbide or cordierite honeycomb substrate with said slurry, iii) drying at room temperature, if necessary, drying and calcination in a furnace after immersing said dried or calcinated honeycomb substrate in silver chloride (AgCl) , silver nitrate (AgNO3) , silver sulfate (Ag2SO4) or its mixture solution and iv) drying
and calcination in a furnace after coating by immersing said substrate impregnated with silver component in aqueous HCl solution controlled at pH 3 ~ 6.5 sufficiently. In these steps, said drying and calcination in a furnace are performed by drying at 80 ~ 150 0C for 1 - 5 hours after heating from the room temperature slowly, and then calcination at 450 ~ 600 0C for 1 - 5 hours after heating slowly. Also, it is possible to prepare the catalyst by the steps of : i) solubilizing the silver compound in aqueous HCl solution controlled at pH 3 - 6.5, ii) coating by immersing alumina-coated substrate in said solution and iii) drying and calcinations at said conditions.
[Description of Drawings]
FIG. 1 shows the NOx conversion of the catalyst according to Example 1 and Comparative Example 1. The amount of impregnated silver is 4.0 wt% in FIG. 1 and 7.0 wt% in FIG. 2.
FIG. 3 shows the NOx conversion of the catalyst according to Example 2 and Comparative Example 2. The amount of impregnated silver is 2.0 wt% in FIG. 3, 4.0 wt% in FIG.4 and 6.0 wt% in FIG. 5.
FIG. 6 shows the NOx conversion of the catalyst according to Example 3 and Comparative Example 3. [Mode for Invention]
The present invention is described in more detail based on the following examples. But, these examples are not
intended to limit the scope of the present invention.
(Example 1)
Preparation of the catalyst
The uniform alumina slurry was prepared by mixing gamma alumina powder (Al-I, surface area : 210 m2/g, pore volume : 0.5 cc/g, specific gravity : 0.8 g/cc) , acetic acid and distilled water and grinding the mixture using wet ball- milling for 24 hours. The average particle size of the resulting alumina was 2 ~ 8 micrometers .
The cordierite honeycomb (size : 2.5 x 2.5 x 2.5 cm, 400 cpsi) was wash-coated with said alumina slurry, in that the amount of impregnated alumina was 0.244 g/cm3. It was dried at 120 0C for 2 hours after heating from the room temperature to 120 °C (heating rate : 5 °C/min) , and then calcinated at 550 0C for 3 hours after heating from 120 0C to 550 °C (heating rate : 5 °C/min) .
Said calcinated cordierite was immersed in silver nitrate solution, in that the amount of impregnated silver was 4.0 and 7.0 wt% per weight of alumina. It was dried and calcinated in the same condition.
The substrate impregnated with silver was immersed in aqueous HCl solution diluted to pH 5.0 for 20 seconds, and then dried and calcinated in the same condition. Finally, the
substrate impregnated with chlorine and silver was prepared.
Efficiency evaluation of the catalyst
Said prepared honeycomb catalyst was used in the test for reducing nitrogen oxides of the model reaction gas mixture having similar composition with real exhaust gas of motor vehicle. The honeycomb catalyst was fixed inside the stainless steel reactor and the thermocouple was set at inlet and outlet of the catalyst. The temperature of the reactor was controlled using the cylindrical furnace carefully.
Each gas flow was controlled using the mass flowmeter exactly, in that the space velocity of the reactant was 50,000 hr"1. Propylene, which is known to diesel-like gas, was used as a reducing agent and the mole ratio of reducing agent/NOx was maintained to 5.
Table 1 shows the composition of the exhaust gas injected to said reactor.
(Table 1)
The concentration of exhaust gas (NO, NO2, THC, CO and N2O) at inlet and outlet of reactor was measured using the quantitation-precision gas analyzer, which adopt
chemiluminescent method or infrared spectroscopy, connected to reactor directly. These results were shown in FIG. 1 andFIG. 2.
(Comparative Example 1)
Except not immersing the substrate in aqueous HCl solution in the preparation of the catalyst, the same processes according to Example 1 were performed. These results were shown in FIG. 1 and FIG. 2 together with the results of Example 1.
As shown in FIG. 1 and FIG. 2, the alumina carrier impregnated with silver and chlorine component according to Example 1 showed a good catalytic characteristics of 80 ~ 88% (maximum activity) near 450 0C and showed an excellent catalytic activity at entire temperature range. But, the alumina carrier impregnated with silver component only according to Comparative Example 1 showed 10 ~ 20% lower activity near maximum activity temperature and showed 50% lower catalytic activity at entire temperature range compared to the catalyst of Example 1.
(Example 2)
In the preparation of the catalyst according to Example 1,
gamma alumina powder (Al-2, surface area : 274 m2/g, pore volume : 0.5 cc/g, specific gravity : 0.6 g/cc) was used and the amount of impregnated silver was 2.0, 4.0 and 6.0 wt% per weight of alumina. Then, it was dried and calcinated in the same condition of wash-coating.
The substrate impregnated with silver was immersed in aqueous HCl solution diluted to pH 5.5 for 20 seconds, and then dried and calcinated in the same condition of wash- coating. Finally, the substrate impregnated with chlorine and silver was prepared.
The efficiency evaluation of the catalyst was performed according to Example 1. These results were shown in FIG. 3, FIG.4 and FIG. 5.
(Comparative Example 2)
Except not immersing the substrate in aqueous HCl solution in the preparation of the catalyst, the same processes according to Example 2 were performed. These results were shown in FIG. 3, FIG. 4 and FIG. 5 together with the results of Example 2.
As shown in FIG. 3 ~ FIG. 5, the alumina carrier impregnated with silver and chlorine component according to Example 2 showed a high catalytic activity at entire
temperature range compared to the alumina carrier impregnated with silver component only according to Comparative Example 2.
(Example 3)
In the preparation of the catalyst according to Example 2, the substrate was immersed in silver nitrate solution, in that the amount of impregnated silver was 2.0 wt% per weight of alumina. Then, it was dried and calcinated in the same condition of wash-coating.
The substrate impregnated with silver was immersed in aqueous HCl solution diluted to pH 5.5 for 20 seconds, and then dried and calcinated in the same condition of wash- coating. Finally, the substrate impregnated with chlorine and silver was prepared. The efficiency evaluation of the catalyst was performed according to Example 1. This result was shown in FIG. 6.
(Comparative Example 3)
In the preparation of the catalyst according to Example 2, the substrate coated with alumina was immersed in aqueous HCl solution diluted to pH 5.5 for 20 seconds before in silver nitrate solution, and then dried and calcinated in the same condition of wash-coating.
The substrate impregnated with chlorine was immersed in silver nitrate solution, in that the amount of impregnated silver was 2.0 wt% per weight of alumina. Then, it was dried and calcinated in the same condition of wash-coating. This result was shown in FIG. 6 together with the result of Example 3.
As shown in FIG. 6, if the substrate was impregnated with silver and then with chlorine, the maximum NOx conversion was 88%. On the other hand, if the substrate was impregnated with chlorine and then with silver, the maximum NOx conversion was
77%, which was about 10% lower than the former case.
From the results of said examples, it was found that the efficiency of the catalyst for reducing nitrogen oxides was improved considerably if the catalyst impregnated with silver was impregnated with chlorine, which is the catalytic component of the present invention. Also, it was found that the catalyst impregnated with silver and then with chlorine showed a high catalytic efficiency compared to the catalyst impregnated with chlorine and then with silver.
[industrial Applicability]
The catalyst impregnated with silver and chlorine component according to the present invention showed an
excellent catalytic efficiency for reducing nitrogen oxides, and showed a superior catalytic efficiency at wide temperature range compared to the current catalyst .
Claims
[CLAIMS] [Claim l]
Catalyst for removing nitrogen oxides with reducing agent comprising the support coated with the catalyst prepared by impregnating the carrier with silver (Ag) and chlorine component .
[Claim 2]
The catalyst for removing nitrogen oxides with reducing agent of claim 1, wherein the amount of impregnated silver component is 0.1 to 10 wt% per weight of the carrier.
[Claim 3]
The catalyst for removing nitrogen oxides with reducing agent of claim 2, wherein said chlorine component is impregnated by immersing the carrier impregnated with silver component in aqueous HCl solution controlled at pH 3 ~ 6.5.
[Claim 4] The catalyst for removing nitrogen oxides with reducing agent of any one of claims 1 to 3 , wherein the catalyst is prepared by calcinating the support coated with the carrier impregnated with said catalytic component at 450 ~ 600 0C.
[Claim 5]
The catalyst for removing nitrogen oxides with reducing agent of claim 4, wherein said carrier is alumina having amorphous, gamma, theta or eta typed crystal structure.
[Claim 6]
The catalyst for removing nitrogen oxides with reducing agent of claim 4, wherein said silver component is silver chloride (AgCl) , silver nitrate (AgNO3) , silver sulfate (Ag2SO4) or its mixture.
[Claim 7]
Preparation method of the catalyst for removing nitrogen oxides with reducing agent comprising the steps of : i) preparing the uniform alumina slurry by adding the alumina to deionized distilled water and ball-milling, ii) drying or drying and calcination after coating silicon carbide or cordierite honeycomb substrate with said slurry, iii) drying at room temperature or drying and calcination after immersing said dried or calcinated honeycomb substrate in silver precursor solution and iv) drying and calcination after coating by immersing said substrate impregnated with silver component in aqueous HCl solution.
[Claim θ] The preparation method of the catalyst for removing nitrogen
oxides with reducing agent of claim 7, wherein the pH of said aqueous HCl solution is 3 ~ 6.5.
[Claim 9] The preparation method of the catalyst for removing nitrogen oxides with reducing agent of claim 7 or 8, wherein said drying and calcination steps are performed by drying at 80 ~ 150 0C for 1 - 5 hours and calcination at 450 ~ 600 °C for 1 - 5 hours .
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| KR1020060003315A KR101096196B1 (en) | 2006-01-11 | 2006-01-11 | Catalyst for the removal of nitrogen oxides with reducing agent and its preparation method |
| KR10-2006-0003315 | 2006-01-11 |
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| CN114100641A (en) * | 2021-12-14 | 2022-03-01 | 宁波市海智材料产业创新研究院 | AgCl/Al2O3Preparation method of catalyst, catalyst and application |
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| KR101160399B1 (en) * | 2010-02-02 | 2012-06-26 | 주식회사 젬백스앤카엘 | A Coating Method Of MMOMethan Mono-Oxygenase Catalyst For Reduction Of Nitrogen Oxides And A Supporting Body Using The Same |
| KR101460437B1 (en) | 2013-03-29 | 2014-11-12 | 고려대학교 산학협력단 | Nano-catalytic filter and manufacturing method thereof |
| US11071946B2 (en) | 2013-03-29 | 2021-07-27 | Korea University Research And Business Foundation | Nano-catalyst filter and production method for same |
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|---|---|---|---|---|
| JPH0952047A (en) * | 1995-08-17 | 1997-02-25 | Sekiyu Sangyo Kasseika Center | Catalyst for contact reducing nitrogen oxide |
| JPH09168720A (en) * | 1995-12-20 | 1997-06-30 | Tosoh Corp | Removing method for nitrogen oxide |
| JPH09239271A (en) * | 1996-03-05 | 1997-09-16 | Hino Motors Ltd | Exhaust gas purifying catalyst and its production |
| JPH10202064A (en) * | 1997-01-24 | 1998-08-04 | Sekiyu Sangyo Kasseika Center | Method for catalytically reducing nitrogen oxide |
| JP2002015106A (en) * | 2000-06-29 | 2002-01-18 | Ricoh Co Ltd | Workflow system, document acknowleding method and storage medium |
| US20030118960A1 (en) * | 2001-12-21 | 2003-06-26 | Balmer-Millar Mari Lou | Lean NOx aftertreatment system |
-
2006
- 2006-01-11 KR KR1020060003315A patent/KR101096196B1/en active IP Right Grant
- 2006-11-15 WO PCT/KR2006/004802 patent/WO2007081084A1/en active Application Filing
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0952047A (en) * | 1995-08-17 | 1997-02-25 | Sekiyu Sangyo Kasseika Center | Catalyst for contact reducing nitrogen oxide |
| JPH09168720A (en) * | 1995-12-20 | 1997-06-30 | Tosoh Corp | Removing method for nitrogen oxide |
| JPH09239271A (en) * | 1996-03-05 | 1997-09-16 | Hino Motors Ltd | Exhaust gas purifying catalyst and its production |
| JPH10202064A (en) * | 1997-01-24 | 1998-08-04 | Sekiyu Sangyo Kasseika Center | Method for catalytically reducing nitrogen oxide |
| JP2002015106A (en) * | 2000-06-29 | 2002-01-18 | Ricoh Co Ltd | Workflow system, document acknowleding method and storage medium |
| US20030118960A1 (en) * | 2001-12-21 | 2003-06-26 | Balmer-Millar Mari Lou | Lean NOx aftertreatment system |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114100641A (en) * | 2021-12-14 | 2022-03-01 | 宁波市海智材料产业创新研究院 | AgCl/Al2O3Preparation method of catalyst, catalyst and application |
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| KR20070075044A (en) | 2007-07-18 |
| KR101096196B1 (en) | 2011-12-22 |
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