WO2008117941A1 - Doc catalyst employing pd-au for improving diesel oxidation activity - Google Patents
Doc catalyst employing pd-au for improving diesel oxidation activity Download PDFInfo
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- WO2008117941A1 WO2008117941A1 PCT/KR2008/001264 KR2008001264W WO2008117941A1 WO 2008117941 A1 WO2008117941 A1 WO 2008117941A1 KR 2008001264 W KR2008001264 W KR 2008001264W WO 2008117941 A1 WO2008117941 A1 WO 2008117941A1
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- Prior art keywords
- doc
- diesel oxidation
- palladium
- support
- platinum
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- 239000003054 catalyst Substances 0.000 title claims abstract description 54
- 230000010718 Oxidation Activity Effects 0.000 title claims abstract description 10
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical group [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 claims abstract description 88
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims abstract description 70
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 39
- 230000003647 oxidation Effects 0.000 claims abstract description 38
- 229910052763 palladium Inorganic materials 0.000 claims abstract description 35
- 229910052697 platinum Inorganic materials 0.000 claims abstract description 29
- 229910001020 Au alloy Inorganic materials 0.000 claims abstract description 14
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 21
- 230000009970 fire resistant effect Effects 0.000 claims description 5
- 229930195733 hydrocarbon Natural products 0.000 description 38
- 150000002430 hydrocarbons Chemical class 0.000 description 38
- 239000010931 gold Substances 0.000 description 23
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 17
- 229910002091 carbon monoxide Inorganic materials 0.000 description 17
- 238000006243 chemical reaction Methods 0.000 description 16
- 239000000203 mixture Substances 0.000 description 11
- 239000010970 precious metal Substances 0.000 description 10
- 230000000052 comparative effect Effects 0.000 description 8
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 7
- 229910052737 gold Inorganic materials 0.000 description 7
- 238000000034 method Methods 0.000 description 7
- 230000000694 effects Effects 0.000 description 6
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 6
- 239000013618 particulate matter Substances 0.000 description 5
- 239000012071 phase Substances 0.000 description 5
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 4
- 230000003197 catalytic effect Effects 0.000 description 4
- 150000001875 compounds Chemical class 0.000 description 4
- 239000007789 gas Substances 0.000 description 4
- 229910052760 oxygen Inorganic materials 0.000 description 4
- 239000001301 oxygen Substances 0.000 description 4
- 239000000377 silicon dioxide Substances 0.000 description 4
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 3
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 3
- 239000002002 slurry Substances 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 2
- 239000000446 fuel Substances 0.000 description 2
- -1 long-chain HC Chemical class 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 1
- 239000005977 Ethylene Substances 0.000 description 1
- 229910002651 NO3 Inorganic materials 0.000 description 1
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 1
- IOVCWXUNBOPUCH-UHFFFAOYSA-M Nitrite anion Chemical compound [O-]N=O IOVCWXUNBOPUCH-UHFFFAOYSA-M 0.000 description 1
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 1
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- XTXRWKRVRITETP-UHFFFAOYSA-N Vinyl acetate Chemical compound CC(=O)OC=C XTXRWKRVRITETP-UHFFFAOYSA-N 0.000 description 1
- MCMNRKCIXSYSNV-UHFFFAOYSA-N ZrO2 Inorganic materials O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 1
- 238000007792 addition Methods 0.000 description 1
- 238000003915 air pollution Methods 0.000 description 1
- 229910000323 aluminium silicate Inorganic materials 0.000 description 1
- 150000001412 amines Chemical class 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 229910000422 cerium(IV) oxide Inorganic materials 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 229910052878 cordierite Inorganic materials 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 230000002542 deteriorative effect Effects 0.000 description 1
- 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 description 1
- 239000000295 fuel oil Substances 0.000 description 1
- 239000007792 gaseous phase Substances 0.000 description 1
- 150000002344 gold compounds Chemical class 0.000 description 1
- 150000004820 halides Chemical class 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- 230000002779 inactivation Effects 0.000 description 1
- 229910052747 lanthanoid Inorganic materials 0.000 description 1
- 150000002602 lanthanoids Chemical class 0.000 description 1
- 229910052746 lanthanum Inorganic materials 0.000 description 1
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 150000002736 metal compounds Chemical class 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000010705 motor oil Substances 0.000 description 1
- RVTZCBVAJQQJTK-UHFFFAOYSA-N oxygen(2-);zirconium(4+) Chemical compound [O-2].[O-2].[Zr+4] RVTZCBVAJQQJTK-UHFFFAOYSA-N 0.000 description 1
- 150000002940 palladium Chemical class 0.000 description 1
- GPNDARIEYHPYAY-UHFFFAOYSA-N palladium(ii) nitrate Chemical compound [Pd+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O GPNDARIEYHPYAY-UHFFFAOYSA-N 0.000 description 1
- 150000003058 platinum compounds Chemical class 0.000 description 1
- 231100000614 poison Toxicity 0.000 description 1
- 231100000572 poisoning Toxicity 0.000 description 1
- 230000000607 poisoning effect Effects 0.000 description 1
- 230000007096 poisonous effect Effects 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 229910052761 rare earth metal Inorganic materials 0.000 description 1
- 150000002910 rare earth metals Chemical class 0.000 description 1
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 1
- 229910010271 silicon carbide Inorganic materials 0.000 description 1
- SDKPSXWGRWWLKR-UHFFFAOYSA-M sodium;9,10-dioxoanthracene-1-sulfonate Chemical compound [Na+].O=C1C2=CC=CC=C2C(=O)C2=C1C=CC=C2S(=O)(=O)[O-] SDKPSXWGRWWLKR-UHFFFAOYSA-M 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
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 229910001928 zirconium oxide Inorganic materials 0.000 description 1
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
- B01J23/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the platinum group metals
-
- 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
- B01D53/944—Simultaneously removing carbon monoxide, hydrocarbons or carbon making use of oxidation catalysts
-
- 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
- B01J23/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the platinum group metals
- B01J23/44—Palladium
-
- 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
- B01J23/52—Gold
-
- B01J35/19—
-
- 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
- B01D2255/102—Platinum group metals
- B01D2255/1021—Platinum
-
- 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
- B01D2255/102—Platinum group metals
- B01D2255/1023—Palladium
-
- 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
- B01D2255/106—Gold
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2255/00—Catalysts
- B01D2255/20—Metals or compounds thereof
- B01D2255/209—Other metals
- B01D2255/2092—Aluminium
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2255/00—Catalysts
- B01D2255/90—Physical characteristics of catalysts
- B01D2255/92—Dimensions
- B01D2255/9207—Specific surface
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2257/00—Components to be removed
- B01D2257/70—Organic compounds not provided for in groups B01D2257/00 - B01D2257/602
- B01D2257/702—Hydrocarbons
- B01D2257/7022—Aliphatic hydrocarbons
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2258/00—Sources of waste gases
- B01D2258/01—Engine exhaust gases
- B01D2258/012—Diesel engines and lean burn gasoline engines
-
- 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
Definitions
- the present invention relates to a diesel oxidation catalyst (DOC) employing Pd-Au for improving diesel oxidation activity, and, more particularly, to a diesel oxidation catalyst (DOC), further including a Pd-Au alloy-containing support, thus increasing HC oxidation activity.
- DOC diesel oxidation catalyst
- a diesel engine which is a compression ignition engine, has high thermal efficiency at low vehicle speeds, it is advantageously used as a power source for a vehicle.
- a diesel engine is operated under a lean fuel condition, that is, at a high air/fuel (A/F) ratio, a diesel automobile discharges a very small amount of hydrocarbons (HC) and carbon monoxide (CO) compared to a gasoline automobile, but discharges a relatively large amount of NO and particulate matter
- DOC diesel oxidation catalyst
- PM particulate filter
- diesel automobiles in order to meet automobile exhaust gas regulations, diesel automobiles must be provided therein with a diesel oxidation catalyst (DOC) to remove HC and CO, make up for the activity of nitrogen oxides (NO ) and realize a natural re- generation type filter system.
- DOC diesel oxidation catalyst
- NO nitrogen oxides
- SO sulfuric acid
- Korean Patent Registration No. 361419 discloses a ceria-alumina oxidation catalyst and a method of using the same. It is mentioned in the patent document that a composition for the ceria-alumina oxidation catalyst includes enough platinum and palladium to accelerate the oxidation of gaseous CO and HC as catalytic components of the ceria-alumina oxidation catalyst having a predetermined surface area.
- the conventional ceria-alumina oxidation catalyst is problematic in that its specific surface area is decreased due to carbon deposition and sulfur poisoning, causing inactivation of the catalyst, and thus its activity is deter iorated with the passage of time when it is actually installed in a vehicle.
- Korean Patent Registration No. 279938 discloses an oxidation catalyst composition for a diesel engine, comprising an active alumina having larger micropores, impregnated with 0.5 - 1.0 wt% of platinum compound, and metal compounds. Disclosure of Invention Technical Problem
- palladium (Pd) has higher activity than does platinum (Pt) at high temperature, so that some of platinum (Pt) can be replaced with palladium (Pd).
- Pt palladium
- an object of the present invention is to provide a diesel oxidation catalyst (DOC) which can overcome the problem of the HC LOT increase in the diesel oxidation catalyst in which some of the platinum is replaced with palladium.
- DOC diesel oxidation catalyst
- the present invention provides a diesel oxidation catalyst (DOC), further including a Pd-Au alloy-containing support, thus increasing HC oxidation activity.
- DOC diesel oxidation catalyst
- a Pd-Au alloy-containing support is known as a catalyst for converting ethylene into vinyl acetate in a gaseous phase using acetic acid, oxygen or oxygen-containing gas.
- U.S. Patent No. 4,048,096 discloses a method of preparing a catalyst comprising palladium and gold deposited on a catalyst support. In this method, a catalyst support is impregnated with an aqueous solution including a mixture of palladium salt and gold salt, a precious metal salt is converted into a water-insoluble compound by alkaline treatment, and then the water-insoluble compound is supported on the catalyst support.
- the prepared Pd-Au alloy-containing support includes 0.5 ⁇ 2.0 wt% of palladium and 0.2 - 1.3 wt% of gold, and preferably, may further include 0.01 - 1.0 wt% of lanthanides and/or compounds thereof (refer to Korean Patent Registration No. 550813).
- Pd-Au alloy-containing support is applied to a diesel oxidation catalyst (DOC).
- DOC diesel oxidation catalyst
- the Pd-Au alloy-containing support used in the present invention is supported on alumina doped with 1.67 wt% of Pd and 2.00 wt% of Au.
- alumina instead of alumina, silica, aluminosilicate, silicate, titanium oxide, zirconium oxide, titanate, silicon carbide, or carbon may be used.
- water-soluble salts such as chloride, halides, nitrate, nitrite, hydroxide, oxide, oxalate, acetate and amine, may be applied to a precursor solution containing palladium and gold.
- the present invention provides a diesel oxidation catalyst (DOC) which has an improved HC conversion rate when the Pd-Au alloy-containing support is applied to a conventional palladium-containing catalyst.
- DOC diesel oxidation catalyst
- the DOC catalyst according to the present invention is advantageous in that the problem that occurs when some of the platinum is replaced with palladium in a conventional palladium-containing catalyst, that is, the deterioration of HC activity at low temperature, can be solved because the Pd-Au alloy-containing support is additionally applied to the conventional palladium-containing catalyst, so that the problem of activity that occurs when platinum in a DOC composition is replaced with palladium, which is cheaper than platinum, can also be solved.
- FIG. 1 is graphs showing the respective HC conversion rates of a Pd-Au containing diesel oxidation catalyst (DOC) and comparative diesel oxidation catalysts (DOCs); and
- FIG. 2 is a graph comparing the HC conversion rate and CO conversion rate of a
- a diesel oxidation catalyst (DOC) includes precious metals, such as platinum, palladium, and the like, and is used together with a fire-resistant oxide support having a high surface area, such as high surface area alumina.
- the fire- resistant oxide support is supported on a monolithic carrier. Further, a fire-resistant oxide having a high surface area is used as a support for a DOC.
- high surface area alumina referred to as 'gamma-alumina' or 'active alumina', has a BET (Brunauer, Emmett and Teller) surface area of 60 or more (m /g), and such active alumina generally has a gamma phase and a delta phase, but may have an eta phase, a kappa phase and a theta phase.
- a DOC composition includes platinum (Pt) and palladium (Pd) such that the weight ratio of platinum and palladium is 2: 1, and the method of preparing a DOC composition containing platinum and palladium is commonly known.
- the present invention provides a diesel oxidation catalyst (DOC) supported with precious metals including platinum and palladium, and, particularly, a diesel oxidation catalyst further including a Pd-Au alloy-containing support.
- DOC diesel oxidation catalyst
- the diesel oxidation catalyst (DOC) of the present invention can solve the HC LOT problem occurring when some of the platinum is replaced with palladium.
- the diesel oxidation catalyst (DOC) according to an embodiment of the present invention is formed by impregnating a first Pd-Au alloy-containing support and a second support with precious metals including platinum and palladium. Further, the diesel oxidation catalyst (DOC) according to an embodiment of the present invention may include rare-earth metals for storing oxygen.
- the first support and the second support are fire-resistant oxide supports having surface areas the same as each other or different from each other.
- the second support may be selected from the group consisting of silica, alumina, and titania.
- the second support is an active compound selected from the group consisting of alumina, silica, alumina- silica, alumi- nosilicate, alumina-zirconia, alumina-chromia and alumina-ceria, and, more preferably, is active alumina.
- DOC diesel oxidation catalyst
- platinum (Pt) is not mentioned, but this is to simplify a test, and does not mean that the diesel oxidation catalyst (DOC) of the present invention does not include platinum (Pt) as a component.
- the following Catalytic Protocol is a test for illustrating the fact that gold (Au) weakens the bonding force between palladium (Pd) and long-chain HC, thus increasing the HC conversion rate.
- a Pd/ Al O DOC was produced using the same method as in Example 1, except that only the second gamma-alumina powder support was used.
- a Pd/ Al O DOC was produced using the same method as in Example 1, except that active alumina doped with 10 wt% of lanthanum was used.
- FIG. 1 shows the respective HC conversion rates of a Pd-Au containing diesel oxidation catalyst (DOC) and comparative diesel oxidation catalysts (DOCs), which were aged at an inlet temperature of 65O 0 C and 75O 0 C. From FIG. 2, it can be seen that the HC conversion rate of the DOC of Example 1 was increased to about 2-6% of that of the DOCs of Comparative Examples 1 and 2.
- DOC diesel oxidation catalyst
- DOCs comparative diesel oxidation catalysts
- Example 1 the DOC (aged at 65O 0 C) of Example 1 and the DOC of Comparative Example 1 were real-car-tested using a Pride (1.5L), and thus the HC conversion rates and CO conversion rates thereof were measured, and the results thereof are shown in FIG. 2.
- FIG. 2 it can be seen that the HC conversion rate of the DOC of the present invention was remarkably improved compared to the CO conversion rate thereof. This result coincides with the theoretical prediction that gold (Au) weakens the bonding force between palladium (Pd) and long-chain HC.
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- Chemical Kinetics & Catalysis (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Combustion & Propulsion (AREA)
- Biomedical Technology (AREA)
- Environmental & Geological Engineering (AREA)
- Analytical Chemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Catalysts (AREA)
- Exhaust Gas After Treatment (AREA)
Abstract
The present invention relates to a diesel oxidation catalyst (DOC) employing Pd-Au for improving diesel oxidation activity, and, more particularly, to a diesel oxidation catalyst (DOC), further including a Pd-Au alloy-containing support, thus solving the conventional problem occurring when some of the platinum is replaced with palladium and increasing HC oxidation activity.
Description
Description
DOC CATALYST EMPLOYING PD-AU FOR IMPROVING DIESEL OXIDATION ACTIVITY
Technical Field
[1] The present invention relates to a diesel oxidation catalyst (DOC) employing Pd-Au for improving diesel oxidation activity, and, more particularly, to a diesel oxidation catalyst (DOC), further including a Pd-Au alloy-containing support, thus increasing HC oxidation activity. Background Art
[2] Generally, since a diesel engine, which is a compression ignition engine, has high thermal efficiency at low vehicle speeds, it is advantageously used as a power source for a vehicle. Meanwhile, since a diesel engine is operated under a lean fuel condition, that is, at a high air/fuel (A/F) ratio, a diesel automobile discharges a very small amount of hydrocarbons (HC) and carbon monoxide (CO) compared to a gasoline automobile, but discharges a relatively large amount of NO and particulate matter
(PM), thus causing air pollution.
[3] In order to overcome the above problem, as post-treatment technologies, i) a diesel oxidation catalyst (DOC) for purifying high boiling point hydrocarbons of particulate matter, ii) a deNO catalyst for decomposing or reducing NO in an excess oxygen atmosphere, and iii) a diesel particulate filter for removing particulate matter (PM) are considered. [4] Diesel automobiles are relatively satisfactory in the emission of HC and CO.
However, in order to meet automobile exhaust gas regulations, diesel automobiles must be provided therein with a diesel oxidation catalyst (DOC) to remove HC and CO, make up for the activity of nitrogen oxides (NO ) and realize a natural re- generation type filter system. When exhaust gas emitted from a diesel engine passes through a diesel oxidation catalyst (DOC), CO and HC are oxidized into CO and H O. Meanwhile, in the DOC, SO , derived from fuel and engine oil, is oxidized into sulfuric acid, which is poisonous to the DOC, thus deteriorating the durability of DOC.
[5] Several conventional technologies related to DOCs have been disclosed.
[6] As the conventional technologies, Korean Patent Registration No. 361419 discloses a ceria-alumina oxidation catalyst and a method of using the same. It is mentioned in the patent document that a composition for the ceria-alumina oxidation catalyst includes enough platinum and palladium to accelerate the oxidation of gaseous CO and HC as catalytic components of the ceria-alumina oxidation catalyst having a predetermined surface area. However, the conventional ceria-alumina oxidation catalyst is
problematic in that its specific surface area is decreased due to carbon deposition and sulfur poisoning, causing inactivation of the catalyst, and thus its activity is deter iorated with the passage of time when it is actually installed in a vehicle. Further, Korean Patent Registration No. 279938 discloses an oxidation catalyst composition for a diesel engine, comprising an active alumina having larger micropores, impregnated with 0.5 - 1.0 wt% of platinum compound, and metal compounds. Disclosure of Invention Technical Problem
[7] Recently, as exhaust gas emission regulations become stricter, there is a problem in that the amount of platinum included in a DOC is rapidly increased, and thus the production cost of the DOC is increased. Therefore, in order to solve the problem, some of platinum is being replaced with palladium. Theoretically analyzing the fact that platinum is being replaced with palladium, a DOC is inactive to HC and CO at low temperature, but accelerates the oxidation of HC and CO with the increase in temperature. In most DOC systems including Pt/alumina, CO conversion is higher than HC conversion. That is, additional catalytic components necessary for the HC conversion are required, and palladium (Pd) has higher activity than does platinum (Pt) at high temperature, so that some of platinum (Pt) can be replaced with palladium (Pd). However, when some of platinum (Pt) is replaced with palladium (Pd), the following problems ensue. According to a tendency in the oxidation reaction of CO and HC in the case where only platinum (Pt) is used as a component of a DOC and in the case where platinum (Pt) and palladium (Pd) are used as components of the DOC such that the weight ratio of the platinum (Pt) and palladium (Pd) is 2: 1, in the case where only platinum (Pt) is used as a component of a DOC, the temperature at which CO is oxidized is almost the same as that at which CO+HC are oxidized, but in the case where some of the platinum is replaced with palladium, the temperature at which CO is oxidized is greatly different from that at which CO+HC are oxidized, thereby increasing the HC LOT (Light Off Temperature) in the case where palladium is used for a DOC in place of some of the platinum. This tendency can be understood from the fact that the bonding energy between palladium (Pd) and HC, particularly long-chain HC, is high. Therefore, there is a technical problem in that the HC LOT must be decreased in the case of a catalyst composition in which some of the platinum is replaced with palladium. The characteristics of a catalyst composition may be determined by LOT (Light Off Temperature), and LOT is defined as the temperature at which the HC conversion ratio in a catalyst exceeds 50%. Technical Solution
[8] Accordingly, the present invention has been made keeping in mind the above
problems occurring in the prior art, and an object of the present invention is to provide a diesel oxidation catalyst (DOC) which can overcome the problem of the HC LOT increase in the diesel oxidation catalyst in which some of the platinum is replaced with palladium.
[9] In order to accomplish the above object, the present invention provides a diesel oxidation catalyst (DOC), further including a Pd-Au alloy-containing support, thus increasing HC oxidation activity.
[10] A Pd-Au alloy-containing support is known as a catalyst for converting ethylene into vinyl acetate in a gaseous phase using acetic acid, oxygen or oxygen-containing gas. U.S. Patent No. 4,048,096 discloses a method of preparing a catalyst comprising palladium and gold deposited on a catalyst support. In this method, a catalyst support is impregnated with an aqueous solution including a mixture of palladium salt and gold salt, a precious metal salt is converted into a water-insoluble compound by alkaline treatment, and then the water-insoluble compound is supported on the catalyst support. Subsequently, the palladium and gold compounds included in the catalyst support are reduced using the corresponding precious metals, thus preparing a Pd-Au alloy- containing support. The prepared Pd-Au alloy-containing support includes 0.5 ~ 2.0 wt% of palladium and 0.2 - 1.3 wt% of gold, and preferably, may further include 0.01 - 1.0 wt% of lanthanides and/or compounds thereof (refer to Korean Patent Registration No. 550813).
[11] The present inventors found that HC conversion rate is greatly improved when the
Pd-Au alloy-containing support is applied to a diesel oxidation catalyst (DOC). The theoretical reason for this is not clear, but is assumed to be because gold (Au) weakens the bonding force between palladium (Pd) and long-chain HC.
[12] The Pd-Au alloy-containing support used in the present invention is supported on alumina doped with 1.67 wt% of Pd and 2.00 wt% of Au. However, in the present invention, instead of alumina, silica, aluminosilicate, silicate, titanium oxide, zirconium oxide, titanate, silicon carbide, or carbon may be used. Meanwhile, in the present invention, regardless of the Pd-Au alloy-containing support, it is clear that water-soluble salts, such as chloride, halides, nitrate, nitrite, hydroxide, oxide, oxalate, acetate and amine, may be applied to a precursor solution containing palladium and gold.
[13] The present invention provides a diesel oxidation catalyst (DOC) which has an improved HC conversion rate when the Pd-Au alloy-containing support is applied to a conventional palladium-containing catalyst.
Advantageous Effects
[14] The DOC catalyst according to the present invention is advantageous in that the
problem that occurs when some of the platinum is replaced with palladium in a conventional palladium-containing catalyst, that is, the deterioration of HC activity at low temperature, can be solved because the Pd-Au alloy-containing support is additionally applied to the conventional palladium-containing catalyst, so that the problem of activity that occurs when platinum in a DOC composition is replaced with palladium, which is cheaper than platinum, can also be solved. Brief Description of the Drawings
[15] FIG. 1 is graphs showing the respective HC conversion rates of a Pd-Au containing diesel oxidation catalyst (DOC) and comparative diesel oxidation catalysts (DOCs); and
[16] FIG. 2 is a graph comparing the HC conversion rate and CO conversion rate of a
Pd-Au containing diesel oxidation catalyst (DOC) with those of comparative diesel oxidation catalysts (DOCs). Best Mode for Carrying Out the Invention
[17] Hereinafter, a conventional diesel oxidation catalyst (DOC) composition and a diesel oxidation catalyst (DOC) of the present invention will be described in detail. Generally, a diesel oxidation catalyst (DOC) includes precious metals, such as platinum, palladium, and the like, and is used together with a fire-resistant oxide support having a high surface area, such as high surface area alumina. The fire- resistant oxide support is supported on a monolithic carrier. Further, a fire-resistant oxide having a high surface area is used as a support for a DOC. For example, high surface area alumina, referred to as 'gamma-alumina' or 'active alumina', has a BET (Brunauer, Emmett and Teller) surface area of 60 or more (m /g), and such active alumina generally has a gamma phase and a delta phase, but may have an eta phase, a kappa phase and a theta phase. Generally, a DOC composition includes platinum (Pt) and palladium (Pd) such that the weight ratio of platinum and palladium is 2: 1, and the method of preparing a DOC composition containing platinum and palladium is commonly known.
[18] The present invention provides a diesel oxidation catalyst (DOC) supported with precious metals including platinum and palladium, and, particularly, a diesel oxidation catalyst further including a Pd-Au alloy-containing support. The diesel oxidation catalyst (DOC) of the present invention can solve the HC LOT problem occurring when some of the platinum is replaced with palladium.
[19] The diesel oxidation catalyst (DOC) according to an embodiment of the present invention is formed by impregnating a first Pd-Au alloy-containing support and a second support with precious metals including platinum and palladium. Further, the diesel oxidation catalyst (DOC) according to an embodiment of the present invention
may include rare-earth metals for storing oxygen. The first support and the second support are fire-resistant oxide supports having surface areas the same as each other or different from each other. The second support may be selected from the group consisting of silica, alumina, and titania. Preferably, the second support is an active compound selected from the group consisting of alumina, silica, alumina- silica, alumi- nosilicate, alumina-zirconia, alumina-chromia and alumina-ceria, and, more preferably, is active alumina.
[20] Hereinafter, a diesel oxidation catalyst (DOC) including a first Pd-Au alloy- containing support and a second support according to the present invention will be described in detail. In the following Catalytic Protocol, platinum (Pt) is not mentioned, but this is to simplify a test, and does not mean that the diesel oxidation catalyst (DOC) of the present invention does not include platinum (Pt) as a component. The following Catalytic Protocol is a test for illustrating the fact that gold (Au) weakens the bonding force between palladium (Pd) and long-chain HC, thus increasing the HC conversion rate.
[21] < Method of producing catalyst >
[22] [Example 1]
[23] a. a first Pd-Au alloy-containing support, which is supported on alumina doped with
1.67 wt% of Pd and 2.00 wt% of Au, was mixed with a second gamma-alumina powder support.
[24] b. The mixture of the first support and the second support was formed into a mixed support including 1.7 g/1 of precious metal (Pd) using palladium nitrate, and then the mixed support was dispersed in water to form slurry. The amount of the Pd component was applied with considering the prices of total precious metals (Pd and Au)
[25] c. The slurry was ball-milled such that about 90 % of particles had a particle size of
8 - 10 um, and then a cordierite honeycomb was coated with the ball- milled slurry, dried at a temperature of 15O0C ~ 16O0C for about 10 minutes, and then aged at a temperature of 65O0C for 10 hours (or at a temperature of 75O0C for 10 hours), thereby completing a Pd-Au/Al O DOC.
[26] [Comparative Example 1]
[27] A Pd/ Al O DOC was produced using the same method as in Example 1, except that only the second gamma-alumina powder support was used.
[28] [Comparative Example 2]
[29] A Pd/ Al O DOC was produced using the same method as in Example 1, except that active alumina doped with 10 wt% of lanthanum was used.
[30] The compositions of these Pd- Au/ Al O DOCs are given in Table 1.
[31] Table 1
[32] * Prices of precious metals of Example 1 and Comparative Examples 1 and 2 are the same (Au: 617.7 US$/ounce, Pd: 327.0 US$/ounce). [33] The CO LOTs of these Pd-Au/Al O DOCs were tested, and the results thereof are
2 3 given in Table 2. From Table 2, it can be seen that DOCs including only Pd as a precious metal did not exhibit HC oxidation activity, but the DOC of the present invention, including Au as a precious metal, exhibited improved HC oxidation activity at low temperature.
[34] Table 2
[35] Meanwhile, FIG. 1 shows the respective HC conversion rates of a Pd-Au containing diesel oxidation catalyst (DOC) and comparative diesel oxidation catalysts (DOCs), which were aged at an inlet temperature of 65O0C and 75O0C. From FIG. 2, it can be seen that the HC conversion rate of the DOC of Example 1 was increased to about 2-6% of that of the DOCs of Comparative Examples 1 and 2.
[36] Finally, the DOC (aged at 65O0C) of Example 1 and the DOC of Comparative Example 1 were real-car-tested using a Pride (1.5L), and thus the HC conversion rates and CO conversion rates thereof were measured, and the results thereof are shown in FIG. 2. As shown in FIG. 2, it can be seen that the HC conversion rate of the DOC of the present invention was remarkably improved compared to the CO conversion rate
thereof. This result coincides with the theoretical prediction that gold (Au) weakens the bonding force between palladium (Pd) and long-chain HC.
[37] Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.
Claims
Claims
[1] A diesel oxidation catalyst having improved HC oxidation activity, comprising a first Pd-Au alloy-containing support and a second support, which include platinum (Pt) and palladium (Pd). [2] The diesel oxidation catalyst according to claim 1, wherein the first support and the second support are fire-resistant oxide supports having surface areas, and are the same as each other or different from each other. [3] The diesel oxidation catalyst according to claim 1 or 2, wherein the first support and the second support are active alumina.
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| KR1020070030244A KR100865362B1 (en) | 2007-03-28 | 2007-03-28 | Diesel Oxidation Catalyst employing Pd-Au for improving diesel oxidation activity |
| KR10-2007-0030244 | 2007-03-28 |
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| WO2008117941A1 true WO2008117941A1 (en) | 2008-10-02 |
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| EP2374536A1 (en) | 2010-04-08 | 2011-10-12 | Ford Global Technologies, LLC | Palladium-containing oxidation catalyst on ternary Al-Ti-Zr-oxide |
| CN102389831A (en) * | 2011-09-22 | 2012-03-28 | 南开大学 | Catalyst for preparing propylene through propane catalytic dehydrogenation and preparation method thereof |
| WO2012055730A1 (en) | 2010-10-26 | 2012-05-03 | Umicore Ag & Co. Kg | Diesel oxidation catalyst |
| US8492306B2 (en) | 2011-10-04 | 2013-07-23 | GM Global Technology Operations LLC | Method and apparatus for preparing a catalyst |
| US8551411B2 (en) | 2008-05-09 | 2013-10-08 | Johnson Matthey Public Limited Company | Exhaust system for lean-burn internal combustion engine comprising Pd-Au-alloy catalyst |
| EP2653681A1 (en) * | 2012-04-20 | 2013-10-23 | Umicore AG & Co. KG | Coated diesel particulate filter |
| EP2674584A1 (en) * | 2012-06-14 | 2013-12-18 | Umicore AG & Co. KG | Method for preventing the contamination of an SCR catalyst with platinum |
| WO2015111079A1 (en) | 2014-01-21 | 2015-07-30 | Council Of Scientific & Industrial Research | Non noble metal based diesel oxidation catalyst |
| JP2015521540A (en) * | 2012-06-19 | 2015-07-30 | ジョンソン、マッセイ、パブリック、リミテッド、カンパニーＪｏｈｎｓｏｎ Ｍａｔｔｈｅｙ Ｐｕｂｌｉｃｌｉｍｉｔｅｄ Ｃｏｍｐａｎｙ | Catalyst composition |
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| US8551411B2 (en) | 2008-05-09 | 2013-10-08 | Johnson Matthey Public Limited Company | Exhaust system for lean-burn internal combustion engine comprising Pd-Au-alloy catalyst |
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| US9492787B2 (en) | 2012-06-14 | 2016-11-15 | Unicore Ag & Co. Kg | Method for preventing the contamination by platinum of an SCR catalyst |
| JP2015521540A (en) * | 2012-06-19 | 2015-07-30 | ジョンソン、マッセイ、パブリック、リミテッド、カンパニーＪｏｈｎｓｏｎ Ｍａｔｔｈｅｙ Ｐｕｂｌｉｃｌｉｍｉｔｅｄ Ｃｏｍｐａｎｙ | Catalyst composition |
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| US10646827B2 (en) | 2014-01-21 | 2020-05-12 | Council Of Scientific & Industrial Research | Non noble metal based diesel oxidation catalyst |
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| KR20080087980A (en) | 2008-10-02 |
| KR100865362B1 (en) | 2008-10-24 |
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