WO2012137857A1 - 排ガス浄化装置及びそれを用いた排ガス浄化方法 - Google Patents
排ガス浄化装置及びそれを用いた排ガス浄化方法 Download PDFInfo
- Publication number
- WO2012137857A1 WO2012137857A1 PCT/JP2012/059309 JP2012059309W WO2012137857A1 WO 2012137857 A1 WO2012137857 A1 WO 2012137857A1 JP 2012059309 W JP2012059309 W JP 2012059309W WO 2012137857 A1 WO2012137857 A1 WO 2012137857A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- exhaust gas
- oxidation catalyst
- silver
- ash
- oxidation
- Prior art date
Links
- 238000000746 purification Methods 0.000 title claims abstract description 116
- 238000000034 method Methods 0.000 title claims description 126
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 300
- 230000003647 oxidation Effects 0.000 claims abstract description 299
- 239000003054 catalyst Substances 0.000 claims abstract description 290
- 239000013618 particulate matter Substances 0.000 claims abstract description 204
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims abstract description 98
- 229910052709 silver Inorganic materials 0.000 claims abstract description 97
- 239000004332 silver Substances 0.000 claims abstract description 97
- 239000000126 substance Substances 0.000 claims abstract description 58
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- YPNVIBVEFVRZPJ-UHFFFAOYSA-L silver sulfate Chemical compound [Ag+].[Ag+].[O-]S([O-])(=O)=O YPNVIBVEFVRZPJ-UHFFFAOYSA-L 0.000 claims description 31
- 229910000367 silver sulfate Inorganic materials 0.000 claims description 31
- NDVLTYZPCACLMA-UHFFFAOYSA-N silver oxide Chemical compound [O-2].[Ag+].[Ag+] NDVLTYZPCACLMA-UHFFFAOYSA-N 0.000 claims description 16
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims description 15
- 229910019142 PO4 Inorganic materials 0.000 claims description 9
- 229910052791 calcium Inorganic materials 0.000 claims description 8
- 229910001923 silver oxide Inorganic materials 0.000 claims description 8
- ZXSQEZNORDWBGZ-UHFFFAOYSA-N 1,3-dihydropyrrolo[2,3-b]pyridin-2-one Chemical compound C1=CN=C2NC(=O)CC2=C1 ZXSQEZNORDWBGZ-UHFFFAOYSA-N 0.000 claims description 7
- 229910001958 silver carbonate Inorganic materials 0.000 claims description 7
- LKZMBDSASOBTPN-UHFFFAOYSA-L silver carbonate Substances [Ag].[O-]C([O-])=O LKZMBDSASOBTPN-UHFFFAOYSA-L 0.000 claims description 7
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- 229910000161 silver phosphate Inorganic materials 0.000 claims description 6
- 229940019931 silver phosphate Drugs 0.000 claims description 6
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 abstract description 44
- 229910000389 calcium phosphate Inorganic materials 0.000 abstract description 12
- 235000011010 calcium phosphates Nutrition 0.000 abstract description 12
- 239000007789 gas Substances 0.000 description 303
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- 238000000151 deposition Methods 0.000 description 42
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- 230000000052 comparative effect Effects 0.000 description 25
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- CETPSERCERDGAM-UHFFFAOYSA-N ceric oxide Chemical compound O=[Ce]=O CETPSERCERDGAM-UHFFFAOYSA-N 0.000 description 18
- 229910000422 cerium(IV) oxide Inorganic materials 0.000 description 18
- 238000006243 chemical reaction Methods 0.000 description 18
- 239000011148 porous material Substances 0.000 description 18
- 230000010718 Oxidation Activity Effects 0.000 description 14
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- 150000002500 ions Chemical class 0.000 description 13
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- 238000013461 design Methods 0.000 description 3
- 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 3
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- 229910000505 Al2TiO5 Inorganic materials 0.000 description 1
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- 241001465754 Metazoa Species 0.000 description 1
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- FOIXSVOLVBLSDH-UHFFFAOYSA-N Silver ion Chemical compound [Ag+] FOIXSVOLVBLSDH-UHFFFAOYSA-N 0.000 description 1
- 229910010413 TiO 2 Inorganic materials 0.000 description 1
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- 229910052784 alkaline earth metal Inorganic materials 0.000 description 1
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- KZHJGOXRZJKJNY-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Si]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O KZHJGOXRZJKJNY-UHFFFAOYSA-N 0.000 description 1
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- 229910001849 group 12 element Inorganic materials 0.000 description 1
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- FAHBNUUHRFUEAI-UHFFFAOYSA-M hydroxidooxidoaluminium Chemical compound O[Al]=O FAHBNUUHRFUEAI-UHFFFAOYSA-M 0.000 description 1
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Classifications
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- F01N3/035—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters in combination with other devices with catalytic reactors, e.g. catalysed diesel particulate filters
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
- F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
- F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
- F01N3/103—Oxidation catalysts for HC and CO only
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N9/00—Electrical control of exhaust gas treating apparatus
- F01N9/002—Electrical control of exhaust gas treating apparatus of filter regeneration, e.g. detection of clogging
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- 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
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2255/00—Catalysts
- B01D2255/20—Metals or compounds thereof
- B01D2255/204—Alkaline earth metals
- B01D2255/2045—Calcium
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2255/00—Catalysts
- B01D2255/90—Physical characteristics of catalysts
- B01D2255/915—Catalyst supported on particulate filters
- B01D2255/9155—Wall flow filters
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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
- 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
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N2370/00—Selection of materials for exhaust purification
- F01N2370/02—Selection of materials for exhaust purification used in catalytic reactors
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N2510/00—Surface coverings
- F01N2510/06—Surface coverings for exhaust purification, e.g. catalytic reaction
- F01N2510/065—Surface coverings for exhaust purification, e.g. catalytic reaction for reducing soot ignition temperature
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N2560/00—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics
- F01N2560/08—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics the means being a pressure sensor
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N2560/00—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics
- F01N2560/14—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics having more than one sensor of one kind
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
- F01N2900/06—Parameters used for exhaust control or diagnosing
- F01N2900/0601—Parameters used for exhaust control or diagnosing being estimated
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
- F01N2900/06—Parameters used for exhaust control or diagnosing
- F01N2900/16—Parameters used for exhaust control or diagnosing said parameters being related to the exhaust apparatus, e.g. particulate filter or catalyst
- F01N2900/1606—Particle filter loading or soot amount
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
- F01N2900/06—Parameters used for exhaust control or diagnosing
- F01N2900/16—Parameters used for exhaust control or diagnosing said parameters being related to the exhaust apparatus, e.g. particulate filter or catalyst
- F01N2900/1611—Particle filter ash amount
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D2200/00—Input parameters for engine control
- F02D2200/02—Input parameters for engine control the parameters being related to the engine
- F02D2200/08—Exhaust gas treatment apparatus parameters
- F02D2200/0812—Particle filter loading
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/40—Engine management systems
Definitions
- the present invention relates to an exhaust gas purification apparatus and an exhaust gas purification method using the same.
- Gas discharged from an internal combustion engine contains harmful substances such as particulate matter (PM) generated by combustion, ash composed of additives in oil, and the like.
- particulate substances are known as air pollutants that adversely affect animals and plants. Therefore, it has been studied to use an oxidation catalyst to purify particulate matter discharged from an internal combustion engine.
- Patent Document 1 discloses an oxidation catalyst composed of a carrier made of a complex oxide of cerium and zirconium and Ag or an oxide of Ag carried on the carrier.
- Patent Document 2 oxygen containing at least two selected from the group consisting of alkaline earth metal elements, transition metal elements, Group 12 elements and Group 13 elements
- An oxidation catalyst is disclosed that includes a complex oxide having a releasing ability (all CeZrO 2 is used in the examples) and Ag supported on the complex oxide.
- Patent Document 3 discloses using an oxidation catalyst obtained by firing boehmite on which silver is supported.
- Patent Document 4 discloses an oxidation catalyst in which Ag is supported on TiO 2 .
- Patent Documents 1 to 4 when the ash contained in the gas is deposited on the oxidation catalyst at the time of use, the particulate matter and the oxidation catalyst are separated by the ash. As a result, the purification performance of the particulate matter was deteriorated.
- Patent Document 5 basically uses a filter carrying an oxidation catalyst as a pair of a porous corrugated plate and a porous flat plate.
- the exhaust gas flows into the molded body from one direction of the corrugated plate ridge line, and the exhaust gas flows into the molded body with the unit being laminated so that the corrugated ridge lines of the porous corrugated plate are alternately orthogonal.
- a means for blocking the passage of the exhaust gas is provided on one side of the side opposite to the surface on which the exhaust gas flows and a direction orthogonal to the direction in which the exhaust gas flows, and the means for blocking the passage of the exhaust gas switches between the passage and the blocking of the exhaust gas. It is disclosed that the structure can be configured as follows.
- Patent Document 6 an exhaust gas flow path is provided while a filter carrying an oxidation catalyst has a structure in which a plurality of cells extending in the exhaust gas flow direction are arranged in parallel.
- a plug plate that can close the outlet opening of adjacent cells alternately to form an open cell and a closed cell on the downstream end face of the It is disclosed that it is provided as possible.
- the present invention has been made in view of the above-described problems of the prior art, and the deterioration of the oxidation performance of particulate matter due to ash deposition is sufficiently suppressed, and sufficiently advanced particulate matter even after ash deposition. It is an object of the present invention to provide an exhaust gas purification apparatus capable of exhibiting the oxidation performance of the above, and an exhaust gas purification method using the exhaust gas purification apparatus.
- an exhaust gas purification apparatus including an oxidation catalyst for oxidizing and purifying particulate matter contained in exhaust gas from an internal combustion engine. Ashes are deposited by providing the catalyst with a support made of at least one metal salt selected from the group consisting of Ca sulfate and phosphate, and a silver-containing substance supported on the support. It has been found that the deterioration of the oxidation performance due to is sufficiently suppressed, and it is possible to exhibit a sufficiently high oxidation performance of particulate matter even after ash deposition, and the present invention has been completed.
- the exhaust gas purification apparatus of the present invention is an exhaust gas purification apparatus comprising an oxidation catalyst for oxidizing and purifying particulate matter contained in exhaust gas from an internal combustion engine,
- the oxidation catalyst includes a support made of at least one metal salt selected from the group consisting of Ca sulfate and phosphate, and a silver-containing substance supported on the support.
- the silver-containing substance is preferably at least one selected from the group consisting of silver, silver oxide, silver carbonate, silver sulfate and silver phosphate.
- the oxidation catalyst is a catalyst in which a catalyst including the carrier and the silver-containing substance is supported on a particulate filter.
- the step of bringing the exhaust gas having a lean air-fuel ratio into contact with the oxidation catalyst and the step of bringing the exhaust gas having a rich air-fuel ratio into contact with the oxidation catalyst are alternately performed. It is preferable to further include first control means for controlling so as to.
- the exhaust gas purification apparatus of the present invention preferably further comprises ash accumulation amount estimation means for estimating the amount of ash in the exhaust gas deposited on the oxidation catalyst, and such ash accumulation amount estimation means is provided.
- ash accumulation amount estimation means for estimating the amount of ash in the exhaust gas deposited on the oxidation catalyst.
- control is performed so as to perform a step of bringing the exhaust gas having a rich air-fuel ratio into contact with the oxidation catalyst. It is more preferable to further include a second control means.
- the exhaust gas purification method of the present invention is a method in which the exhaust gas is brought into contact with the oxidation catalyst using an exhaust gas purification device including an oxidation catalyst for oxidizing and purifying particulate matter contained in the exhaust gas from the internal combustion engine.
- the oxidation catalyst comprises a carrier comprising at least one metal salt selected from the group consisting of Ca sulfate and phosphate, and a silver-containing substance carried on the carrier. .
- the silver-containing substance is preferably at least one selected from the group consisting of silver, silver oxide, silver carbonate, silver sulfate, and silver phosphate.
- the oxidation catalyst is a catalyst in which a catalyst comprising the carrier and the silver-containing substance is supported on a particulate filter.
- the step of bringing the exhaust gas having a lean air-fuel ratio into contact with the oxidation catalyst and the step of bringing the exhaust gas having a rich air-fuel ratio into contact with the oxidation catalyst are alternately performed. It is preferable to do.
- the exhaust gas purification device further includes an ash accumulation amount estimating means for estimating an amount of ash in the exhaust gas deposited on the oxidation catalyst, and When the ash accumulation amount estimated by the ash accumulation amount estimation means exceeds a reference value, it is preferable to perform a step of bringing the exhaust gas in which the air-fuel ratio is rich into contact with the oxidation catalyst.
- the exhaust gas purification apparatus and exhaust gas purification method of the present invention sufficiently suppress the reduction in the oxidation performance of particulate matter due to ash deposition, and exhibit sufficiently high oxidation performance of particulate matter even after ash deposition. The reason why it is possible to do this is not necessarily clear, but the present inventors speculate as follows.
- an oxidation catalyst having a silver-containing substance supported on a carrier is used.
- the oxidation of PM when such a silver-containing material is used will be examined.
- a silver-containing material contains an Ag element.
- the Ag element is silver.
- Dissociation from the contained material can produce Ag ions (Ag + ).
- Ag ions Ag + .
- a case where silver sulfate (AgSO 4 ) suitable as a silver-containing material according to the present invention is used will be described as an example.
- the silver-containing substance is supported on a carrier.
- the silver-containing material is used in combination with the carrier as described above, when the silver-containing material is melted, Ag ions generated from the silver-containing material are dispersed so as to cover the entire surface of the carrier.
- the silver-containing material is Ag 2 SO 4
- the melting point is 660 ° C., and it is considered that a part is in a molten state in the temperature region where PM is oxidized. Therefore, in an oxidation catalyst including a silver-containing substance supported on a carrier, the contact point between Ag ions and PM is remarkably increased, and a very high PM oxidation activity can be obtained.
- PM oxidation activity is higher when PM oxidation treatment 2 is employed to oxidize PM. Therefore, when a silver-containing substance is used, an oxidation catalyst supported on a carrier is used, and a control process is performed so that the oxidation catalyst comes into contact with exhaust gas in a rich atmosphere, so that Ag contained in the catalyst is converted into a metal state. Then, the present inventors infer that higher PM oxidation activity can be obtained by contacting the exhaust gas in a lean atmosphere.
- the oxidation catalyst according to the present invention at least one metal salt of Ca sulfate and Ca phosphate is used as the carrier 11, and the silver-containing substance 12 is formed on the carrier 11. It is supported. And since the metal salt utilized for such a support
- carrier is a component contained in ash, it has a property very close to ash. Therefore, as shown in FIG.
- the silver-containing substance 12 receives sulfate ions (SO 4 2 ⁇ ) from the calcium sulfate in the ash 13.
- a mobile silver compound 12 ′ (in this case, Ag 2 SO 4 ) is formed (FIGS. 1B to 1C).
- Ag 2 SO 4 has a melting point of 660 ° C., and a part thereof is in a molten state in a temperature region where PM is oxidized. Therefore, mobility from the support 11 to the surface of the ash 13 is improved. It is a high compound and easily moves on the surface of the ash 13 (surface that can come into contact with exhaust gas).
- the oxidation catalyst according to the present invention can move the silver-containing material 12 onto the surface of the ash 13 even when the ash 13 is deposited. It is possible to sufficiently suppress the contact point from decreasing. In other words, the oxidation catalyst according to the present invention can suppress a decrease in catalytic activity by using the deposited ash itself as a carrier for the catalyst (silver-containing material 12). Therefore, in the present invention, the present inventors speculate that a sufficiently high level of oxidation performance of particulate matter can be exhibited even after the ash 13 is deposited.
- an exhaust gas purifying apparatus capable of sufficiently suppressing a reduction in the oxidation performance of particulate matter due to ash deposition and exhibiting a sufficiently high oxidation performance of particulate matter even after ash deposition. And, it becomes possible to provide an exhaust gas purification method using the exhaust gas purification device.
- FIG.1 (a) is a schematic diagram which shows notionally the state of the oxidation catalyst before use
- FIG.1 (b) is on an oxidation catalyst.
- FIG. 1C is a schematic diagram conceptually showing a state in which ash is deposited
- FIG. 1C is a schematic diagram conceptually showing a state in which a mobile silver compound moves on the surface of ash
- FIG. It is a schematic diagram which shows notionally the state which the silver containing substance precipitated on the surface of the ash deposited on the oxidation catalyst.
- 1 is a schematic diagram showing a preferred embodiment of an exhaust gas purification apparatus of the present invention connected to an internal combustion engine.
- the exhaust gas purification apparatus of the present invention is an exhaust gas purification apparatus comprising an oxidation catalyst for oxidizing and purifying particulate matter contained in exhaust gas from an internal combustion engine,
- the oxidation catalyst comprises a support made of at least one metal salt selected from the group consisting of Ca sulfate and phosphate, and a silver-containing substance supported on the support.
- the carrier in such an oxidation catalyst is made of at least one metal salt selected from the group consisting of Ca sulfate and phosphate.
- the carrier since such a metal salt is used for the carrier, the carrier has properties very close to ash. Therefore, even if ash is deposited, the silver-containing material carried on the carrier is removed. Since it becomes possible to move efficiently on the ash surface and the catalytic active point can be moved onto the ash surface, it is possible to sufficiently suppress a decrease in catalytic activity due to ash deposition. Further, among the metal salts used as such a carrier, from the viewpoint that it is possible to express a higher degree of catalytic activity and more sufficiently suppress the decrease in catalytic activity due to ash deposition, Ca sulfate.
- the ash is basically the same component, and therefore, a silver-containing substance can be more highly dispersed on the ash surface. Therefore, even after ash deposition, there is a tendency that higher catalytic activity can be expressed.
- the carrier made of such a metal salt a particulate material is preferably used from the viewpoint that a large amount of a silver-containing substance can be contained in a highly dispersible state.
- the average primary particle size of the carrier particles is preferably 0.1 to 500 nm, and more preferably 1 to 50 nm.
- the average primary particle diameter of such a carrier can be measured by calculating from the line width of the powder X-ray diffraction peak using the Scherrer's equation using an X-ray diffractometer. .
- the average secondary particle size of the carrier particles is preferably 0.1 to 10 ⁇ m, more preferably 0.1 to 1.0 ⁇ m. If the average secondary particle size is less than the lower limit, the catalyst activity tends to be reduced because it tends to agglomerate in a high temperature atmosphere. On the other hand, if the upper limit is exceeded, the contact property with PM is lost. Therefore, in addition to the decrease in activity, it tends to be difficult to carry on the filter.
- the average secondary particle size of such a carrier can be measured using a laser diffraction particle size distribution measuring device.
- such a carrier preferably has a specific surface area of 0.1 to 300 m 2 / g, and more preferably 1 to 100 m 2 / g.
- the specific surface area is less than the lower limit, the silver-containing material tends not to be sufficiently supported.
- the upper limit is exceeded, the movement of the silver-containing material to the ash tends to be difficult.
- the production method of such a carrier is not particularly limited, and a known method capable of producing the above metal salt can be appropriately used.
- a commercially available metal salt may be used, and the size may be appropriately adjusted by milling with a ball mill or the like.
- a silver-containing substance is supported on the carrier.
- a silver-containing substance contains Ag and is metal-like silver or a silver compound.
- the Ag element in the silver-containing material becomes Ag ions, or the Ag element in the silver-containing material receives sulfate ions (SO 4 2 ⁇ ) from ash.
- AgSO 4 movable silver compound: in the present invention, Ag ion or AgSO 4 is a compound that can move efficiently on the surface of the ash), and the silver-containing substance that is the catalyst component is brought into contact with the exhaust gas.
- the carrier and the silver-containing material it is possible to use the ash deposited at the time of use as a carrier for the silver-containing material, and a sufficiently high catalytic activity even after ash deposition. It is possible to demonstrate.
- silver-containing substance metal-like silver, silver oxide, silver carbonate, silver sulfate, and silver phosphate are preferable, and silver and silver sulfate are more preferable because higher catalytic activity can be obtained.
- silver oxide, silver carbonate, silver sulfate, and silver phosphate are silver sulfate (Ag) when the silver element in the silver-containing material receives sulfate ions (SO 4 2 ⁇ ) from ash during use of the catalyst.
- the form of the silver-containing substance changes depending on the type of carrier used, the atmosphere of the exhaust gas during use, and the ongoing reaction.
- a silver containing material may contain 1 type independently, or may mix and contain 2 or more types.
- the type of the carrier and the type of the silver-containing substance supported on the carrier are confirmed by measuring the X-ray diffraction to obtain the X-ray diffraction pattern and obtaining the type of crystal existing from the peak position. it can.
- the amount of such a silver-containing substance supported is not particularly limited, but is preferably 0.1 to 50 parts by mass with respect to 100 parts by mass of the carrier in terms of silver (metal).
- the part by mass is particularly preferred. If the supported amount of such a silver-containing substance is less than the lower limit, the oxidation performance of the particulate matter tends to be not sufficiently advanced. On the other hand, even if the upper limit is exceeded, the oxidation performance is saturated. Therefore, the cost tends to increase.
- the method for supporting such a silver-containing substance is not particularly limited, and a known method can be used as appropriate.
- a dispersion or sol of a silver-containing substance or a precursor thereof can be used on the surface of the carrier.
- a method of coating on a carrier by using a method of coating (subsequently firing if necessary), a vapor deposition method (for example, chemical vapor deposition method, physical vapor deposition method, sputter vapor deposition method) or the like can be appropriately employed.
- such an oxidation catalyst may be provided with a support made of the metal salt and a silver-containing substance supported on the support, and the form thereof is not particularly limited, and the form of a pellet-shaped pellet catalyst, etc. It is good also as a form carried by the filter.
- a filter is not particularly limited, and a known filter can be used as appropriate.
- a particulate filter (DPF) a monolith filter, a honeycomb filter, a pellet filter, a plate filter And a filter made of foamed ceramic.
- the material of such a filter is not particularly limited, and a known material can be appropriately used.
- a catalyst comprising the carrier and the silver-containing material is used as a particulate filter. More preferably, it is in a supported form.
- a filter having pores having an average pore diameter of 1 to 300 ⁇ m.
- a base material having such an average pore diameter it becomes possible to oxidize and purify the particulate matter more efficiently.
- the thickness of the coating layer is preferably 0.025 to 25 ⁇ m. More preferably, the thickness is 0.035 to 10 ⁇ m. If the thickness of the coat layer is less than the lower limit, the surface of the filter cannot be sufficiently covered by the catalyst including the carrier and the silver-containing material, and the contact point with the particulate matter is reduced, so that a sufficiently high oxidation performance is achieved. On the other hand, when the upper limit is exceeded, the pores of the filter are blocked by the catalyst including the carrier and the silver-containing material, and the pressure loss of the exhaust gas increases and the engine efficiency increases. It tends to decrease.
- the amount of the carrier supported on the filter is not particularly limited, and the amount can be appropriately adjusted according to the internal combustion engine or the like. However, it is preferably 1 to 300 g, more preferably 10 to 100 g, per 1 liter of filter volume. If the amount is less than the lower limit, it tends to be difficult to exhibit sufficiently high catalyst performance. On the other hand, if the amount exceeds the upper limit, the catalyst is provided with the support and the silver-containing substance. The pores are clogged, the pressure loss of the exhaust gas increases, and the engine efficiency tends to decrease.
- such a filter preferably has a porosity of 30 to 70% (more preferably 40 to 65%).
- porosity refers to the volume ratio of the hollow portion inside the substrate.
- the porosity when the porosity is less than the lower limit, the pores tend to be clogged by the particulate matter in the exhaust gas.
- the porosity exceeds the upper limit, it is difficult to collect the particulate matter in the exhaust gas. The strength of the filter tends to decrease.
- the method for producing the oxidation catalyst is not particularly limited.
- a catalyst including the support and the silver-containing substance is prepared in advance.
- the carrier and the silver are carried out by carrying out a method of supporting the carrier on the filter, a step of supporting the carrier on the filter, and a step of supporting the silver-containing substance on the carrier supported on the filter.
- a method of supporting a catalyst having a contained substance on a filter can be appropriately employed.
- the method for supporting the catalyst or the carrier on the filter is not particularly limited, and a known method can be appropriately adopted.
- a slurry of the catalyst or the carrier is prepared, and the slurry is coated on the filter (after that, calcined if necessary)
- the method of performing etc. can be utilized suitably.
- the particulate matter contained in the gas (exhaust gas) discharged from the internal combustion engine is oxidized and removed by the oxidation catalyst. Therefore, in the exhaust gas purification apparatus of the present invention, the oxidation catalyst may be arranged so that the exhaust gas can come into contact with the oxidation catalyst.
- the gas flow in the exhaust pipe through which the exhaust gas from the internal combustion engine flows The oxidation catalyst may be arranged in the path.
- limit especially as such an internal combustion engine A well-known internal combustion engine can be used suitably, For example, the engine (a gasoline engine, a diesel engine, etc.) of a motor vehicle may be sufficient.
- the oxidation catalyst only needs to be provided, and other configurations are not particularly limited, but the step of contacting the oxidation catalyst with exhaust gas having a lean air-fuel ratio ( It is preferable to further include first control means for performing control so that a lean gas supply step) and a step of bringing the exhaust gas in which the air-fuel ratio is rich into contact with the oxidation catalyst (rich gas supply step) are alternately performed.
- first control means for performing control so that a lean gas supply step and a step of bringing the exhaust gas in which the air-fuel ratio is rich into contact with the oxidation catalyst (rich gas supply step) are alternately performed.
- the rich gas supply process is appropriately performed as a catalyst activation process, and then a lean gas supply process is performed to purify particulate matter.
- a step of bringing the exhaust gas having a lean air-fuel ratio into contact with the oxidation catalyst, and a step of bringing the exhaust gas having a rich air-fuel ratio into contact with the oxidation catalyst may be controlled so as to be carried out alternately a plurality of times.
- the first control means can control the ratio of the fuel and oxygen in the exhaust gas (air-fuel ratio) to be rich or lean according to the step to be performed so that the exhaust gas contacts the oxidation catalyst. It is possible.
- the first control means is not particularly limited as a method for bringing the exhaust gas having a rich or lean air-fuel ratio into contact with the oxidation catalyst, and a known method can be appropriately employed.
- the engine speed, the accelerator By creating in advance a map of the relationship between data such as opening, throttle opening, torque, intake flow rate, fuel injection amount, etc.
- the air-fuel ratio of the exhaust gas is set to a specific atmosphere (lean or rich) by separately adding air or fuel to the exhaust gas by a separately provided air introducing means (for example, an air pump) or a fuel ejecting means.
- the air-fuel ratio is rich means an atmosphere in which the equivalent ratio of fuel to oxygen (fuel / oxygen) in the exhaust gas exceeds 1 (more preferably, the equivalent ratio is 1.05 to 1). .5 atmosphere).
- the air-fuel ratio is lean means that the equivalent ratio of fuel to oxygen (fuel / oxygen) in the exhaust gas is less than 1 (more preferably, the equivalent ratio is 0.5 to 0.95). )).
- first control means from the viewpoint of efficiently preventing pressure loss due to particulate matter accumulation, it is determined that the amount of particulate matter accumulation exceeds a reference value (threshold)
- the catalyst temperature can be controlled to increase in the lean gas supply step.
- the method for calculating the amount of particulate matter deposited is not particularly limited, and a known method can be adopted as appropriate. For example, the operating status of the internal combustion engine, the use history of the exhaust gas purification device, etc., and the particulate matter.
- a map relating to the amount of accumulated particulate matter is prepared in advance, and a method for calculating the amount of particulate matter deposited based on the map, detecting the difference in exhaust gas pressure before and after the oxidation catalyst, A method for calculating a deposit amount in advance and calculating a deposit amount of particulate matter based on the map, a method for calculating a deposit amount of particulate matter by correcting a pressure difference with an intake air amount, and The method etc. which employ
- In the exhaust gas purification apparatus of the present invention various sensors necessary for calculating the amount of particulate matter deposited may be used as appropriate.
- the oxidation catalyst since the optimum execution time of each step or the optimum number of times (the number of repetitions) when performing a plurality of times differs depending on the type and temperature of the oxidation catalyst, the oxidation catalyst. It is preferable to perform control so that each step is performed by changing the execution time, the number of repetitions, and the like of each step according to the temperature.
- the method for obtaining the execution time and the number of repetitions is not particularly limited, but there is a relationship between the temperature of the oxidation catalyst and the change in the purification efficiency of the particulate matter due to the change in the time and the number of executions of each step.
- a method may be employed in which a map is created in advance and obtained based on the map.
- the first control means is not particularly limited as long as it enables the above-described control.
- the first control means uses an engine control unit (ECU) connected to the internal combustion engine. It is good.
- ECU engine control unit
- Such an ECU is configured as a computer in which a microprocessor and peripheral devices such as ROM and RAM necessary for its operation are combined.
- the catalyst temperature, the pressure difference between the exhaust gas before and after contacting the oxidation catalyst, the vehicle speed, the engine speed, the torque A means for detecting the above may be further provided, and known means can be appropriately used as such a detecting means.
- the exhaust gas purification apparatus further includes an ash accumulation amount estimating means for estimating the amount of ash in the exhaust gas deposited on the oxidation catalyst.
- the method for estimating the amount of ash deposited on such an oxidation catalyst is not particularly limited, and a known method can be adopted as appropriate.
- the operating status of the internal combustion engine, the usage history of the exhaust gas purification device, and the ash A method for estimating the amount of ash deposited based on the map, a step of contacting exhaust gas having a lean air-fuel ratio with the oxidation catalyst by the first control means, and the oxidation The step of contacting the exhaust gas having a rich air-fuel ratio with the catalyst is alternately performed to sufficiently remove particulate matter, and then the pressure difference between the exhaust gas before and after the oxidation catalyst is detected, and the detected difference is detected.
- a method for estimating the amount of ash deposited on the oxidation catalyst from the pressure may be employed.
- Such ash accumulation amount estimation means is not particularly limited as long as it can estimate the ash accumulation amount accumulated on the oxidation catalyst.
- an engine control unit (ECU) connected to the internal combustion engine is used. It is good also as what to do.
- the pressure difference between the exhaust gas before and after contacting the oxidation catalyst, the vehicle speed, the engine speed, the torque, etc. There may be further provided means for appropriately detecting the necessary data.
- the exhaust gas purifying apparatus of the present invention includes the ash accumulation amount estimation means
- second control means for performing control so that the step of contacting the exhaust gas having a rich air-fuel ratio is performed.
- the ratio of the fuel and oxygen in the exhaust gas is set to a rich atmosphere in accordance with the estimated value of the ash accumulation amount, and the exhaust gas is brought into contact with the oxidation catalyst.
- metal-like Ag can be deposited on the surface of the deposited ash, and the opportunity for contact between PM and active sites can be sufficiently maintained, and sufficiently high PM oxidation activity can be maintained.
- the method for bringing the exhaust gas having a rich air-fuel ratio into contact with the oxidation catalyst by such second control means is not particularly limited.
- the gas in the specific atmosphere described in the first control means described above is contacted.
- a method similar to the method of causing the air-fuel ratio of the exhaust gas to change to a rich atmosphere by changing the operating state of the internal combustion engine may be employed.
- the second control means is not particularly limited.
- an engine control unit (ECU) connected to the internal combustion engine may be used.
- the second control means in order to enable the control by the second control means, is configured to be able to input data from the ash accumulation amount estimation means.
- the atmosphere of the exhaust gas it may be configured to further include means for detecting the pressure difference between the exhaust gas before and after contacting the oxidation catalyst, the vehicle speed, the engine speed, the torque, and the like.
- the exhaust gas purification method of the present invention uses the exhaust gas to be brought into contact with the oxidation catalyst using an exhaust gas purification device provided with an oxidation catalyst for oxidizing and purifying particulate matter contained in the exhaust gas from the internal combustion engine.
- An exhaust gas purification method for purifying a substance The oxidation catalyst comprises a carrier comprising at least one metal salt selected from the group consisting of Ca sulfate and phosphate, and a silver-containing substance carried on the carrier. .
- Such an exhaust gas purification device is the same as the exhaust gas purification device of the present invention.
- a method for bringing the exhaust gas into contact with the oxidation catalyst in such an exhaust gas purification apparatus is not particularly limited, and a known method can be appropriately employed.
- a gas discharged from the internal combustion engine circulates.
- a method of bringing the exhaust gas from the internal combustion engine into contact with the oxidation catalyst by disposing the oxidation catalyst according to the present invention in the exhaust gas pipe may be adopted.
- the step of bringing the exhaust gas in which the air-fuel ratio is lean into contact with the oxidation catalyst (lean gas supply step), and the step of bringing the exhaust gas in which the air-fuel ratio is rich into contact with the oxidation catalyst ( The rich gas supply step) is preferably performed alternately.
- the present invention by carrying out the step of bringing the exhaust gas in which the air-fuel ratio is rich into contact with the oxidation catalyst, metal-like Ag is precipitated in the catalyst to make the catalytic activity higher. And the catalyst can be activated by this process.
- the execution time of each step varies depending on the design of the oxidation catalyst, the type of the internal combustion engine, etc., and thus cannot be generally stated.
- the execution time may be 100 to 500 hours, and the rich gas supply step may be 1 to 60 minutes.
- the above steps are performed when it is determined that the estimated particulate matter deposition amount exceeds a reference value (threshold value). It is preferable. In this case, in order to sufficiently oxidize and purify the particulate matter, it is preferable to carry out each of the above steps under conditions where the temperature is 350 to 650 ° C. If the temperature is less than the lower limit, it tends to be difficult to sufficiently oxidize and purify the particulate matter. On the other hand, if the temperature exceeds the upper limit, the amount of fuel consumed for raising the catalyst temperature is large. The fuel consumption tends to deteriorate.
- a reference value threshold value
- the exhaust gas purification device is further provided with an ash accumulation amount estimating means for estimating the amount of ash in the exhaust gas deposited on the oxidation catalyst, and the ash
- an ash accumulation amount estimating means for estimating the amount of ash in the exhaust gas deposited on the oxidation catalyst, and the ash
- a step of bringing the exhaust gas in which the air-fuel ratio is rich into contact with the oxidation catalyst may be performed.
- the ash deposition amount exceeds the reference value (threshold value)
- the rich gas supply step is performed, so that metal-like silver can be deposited on the surface of the ash, so that the ash is deposited. Even higher catalytic activity can be maintained.
- the reference value (threshold value) of the ash deposition amount varies depending on the design of the oxidation catalyst and the like, and cannot be generally described. From the viewpoint of the oxidation activity of the particulate matter, the value can be appropriately set. Good. Further, when the ash accumulation amount estimated by the ash accumulation amount estimation means exceeds a reference value, a step of bringing the exhaust gas in which the air-fuel ratio is rich into contact with the oxidation catalyst (rich gas supply step) is performed In this case, it is preferable to carry out the rich gas supply step for 1 to 60 minutes under the condition of a temperature of 350 to 550 ° C.
- FIG. 2 is a schematic diagram showing a preferred embodiment of the exhaust gas purifying apparatus of the present invention connected to an internal combustion engine.
- the internal combustion engine 21 the exhaust gas pipe 22 connected to the internal combustion engine, the oxidation catalyst 23 disposed in the gas flow path in the exhaust gas pipe, and the control means 24 connected to the internal combustion engine
- a pressure sensor 25 capable of measuring the pressure of the exhaust gas before and after contacting the oxidation catalyst 23 and a temperature sensor 26 capable of measuring the temperature of the oxidation catalyst 23 are provided.
- an automobile diesel engine is used as the internal combustion engine 21.
- the exhaust gas pipe 22 is not particularly limited, and a known one can be appropriately used. In the present embodiment, a commercially available exhaust gas pipe 22 is used.
- the oxidation catalyst 23 is a catalyst in which a catalyst including the carrier and the silver-containing substance is supported on a particulate filter (DPF).
- DPF particulate filter
- the control means 24 an engine control unit (ECU) is used as the control means 24.
- control means 24 based on a map of the relationship between the data of the engine speed, the accelerator opening, the throttle opening, the torque, the intake flow rate, the fuel injection amount, etc. of the internal combustion engine 21 and the air-fuel ratio of the exhaust gas.
- the air-fuel ratio atmosphere of the exhaust gas brought into contact with the oxidation catalyst is determined, and the air-fuel ratio atmosphere of the exhaust gas is controlled by appropriately changing the amount of fuel added to the internal combustion engine 21, the engine speed, the torque, the intake air amount, and the like. (The first control means).
- a pressure sensor 25 is connected, and based on data inputted from the pressure sensor 25, a difference in pressure of exhaust gas before and after the oxidation catalyst is detected to detect the pressure difference and the particulate matter. It is also possible to calculate the amount of particulate matter deposited based on a map (prepared in advance) relating to the amount deposited.
- the ash accumulation amount is estimated based on a map (created in advance) regarding the history of the operating state (rotation speed, torque, etc.) of the internal combustion engine and the ash accumulation amount.
- the ash accumulation amount estimating means In such a control means 24, the amount of fuel added to the internal combustion engine 21, the engine speed, the torque, the intake air amount, and the like are appropriately changed based on the calculation result of the ash accumulation amount, and the air-fuel ratio of the exhaust gas. It is also possible to control the atmosphere (second control means).
- the pressure sensor 25 and the temperature sensor 26 commercially available equipment is used.
- the arrow in FIG. 2 represents the gas flow conceptually.
- FIG. 3 shows the control in the case where the first control means performs control so that the lean gas supply process is performed in accordance with the amount of particulate matter deposited and the catalyst temperature (control to raise the catalyst temperature in the lean gas supply process).
- the control means 24 detects the pressure difference between the exhaust gas before and after the oxidation catalyst based on the data inputted from the pressure sensor 25 inputted to the control means 24, and based on the data.
- a particulate matter deposition amount M is calculated, and it is determined whether or not the obtained particulate matter deposition amount M (estimated value) exceeds a reference value M1.
- step 2 If the particulate matter deposition amount M exceeds the reference value M1, the process proceeds to step 2. If the particulate matter deposition amount M is equal to or less than the reference value M1, the process returns to the start.
- Step 2 the temperature T of the oxidation catalyst 23 is calculated based on the data input from the temperature sensor 26 in the control means 24, and it is determined whether or not the temperature T of the oxidation catalyst 23 exceeds the reference temperature T1. . If the temperature T of the oxidation catalyst 23 exceeds the reference temperature T1, the process proceeds to step 3. If the temperature T of the oxidation catalyst 23 is equal to or lower than the reference temperature T1, the process proceeds to step 4. In step 4 as described above, the temperature raising operation of the oxidation catalyst 23 is performed, and then the process returns to the start.
- step 4 a method of changing the operating state of the internal combustion engine 21 to raise the exhaust gas temperature is adopted.
- step 3 an operation is performed in which an exhaust gas whose air-fuel ratio is in a lean atmosphere is brought into contact with the oxidation catalyst 23 for t1 hours, and particulate matter in the exhaust gas is oxidized, and the process proceeds to step 5.
- step 5 it is determined whether or not the pressure difference P (differential pressure P) of the exhaust gas before and after contacting the oxidation catalyst 23 is less than P1 based on the data input from the pressure sensor 15 in the control means 24. To do. If the differential pressure P is less than P1, the process proceeds to step 6. If the differential pressure P is equal to or greater than P1, the process returns to the start.
- step 6 the control unit 24 resets the predicted particulate matter deposition amount M to be zero, and then returns to the start.
- the time t1 in Step 3 is a value determined and determined in advance from the viewpoint of the purification efficiency of the particulate matter.
- a temperature T1 can be appropriately changed to a temperature suitable for purifying the particulate matter according to the design of the exhaust gas purifying apparatus such as the type of oxidation catalyst used.
- the temperature T1 may be set to any temperature within the range of 350 to 650 ° C., and the particulate matter purification step may be performed at a high temperature.
- FIG. 4 is a flowchart showing a preferred embodiment of control by the second control means. That is, first, in step 101, the control unit 24 calculates the ash accumulation amount A, and determines whether or not the ash accumulation amount estimated thereby exceeds the reference value A1. If the ash accumulation amount A exceeds the reference value A1, the process proceeds to step 102. If the ash accumulation amount A is equal to or less than the reference value A1, the process returns to the start. In step 102, the control means 24 performs a step (rich gas supply step) of contacting the oxidation catalyst 23 with the exhaust gas having a rich air-fuel ratio for t101 hours to oxidize the ash in the exhaust gas, thereby step 103.
- a step rich gas supply step
- step of contacting the exhaust gas in the rich atmosphere in step 102 can be achieved by appropriately changing the operating state of the internal combustion engine by the control means 24.
- the control unit 24 resets the estimated ash accumulation amount A calculated to zero, and then returns to the start.
- the value of t101 in step 102 is a value determined and determined in advance from the viewpoint of the particulate matter purification performance of the oxidation catalyst. Note that the rich gas supply process in step 102 makes it possible to sufficiently deposit Ag on the surface of the ash, and to sufficiently maintain the purification activity of the particulate matter of the oxidation catalyst.
- the first and second control means control the air-fuel ratio atmosphere of the exhaust gas brought into contact with the oxidation catalyst by changing the operating state of the internal combustion engine 10.
- the method for controlling the air-fuel ratio atmosphere of the exhaust gas brought into contact with the oxidation catalyst is not particularly limited.
- the oxygen concentration in the exhaust gas is set in the region between the internal combustion engine 21 and the oxidation catalyst 23.
- An air-fuel ratio sensor a fuel supply means (for example, a spray-type fuel addition device) or an air pump is connected to the exhaust gas pipe 23, and the air-fuel ratio of the exhaust gas is measured using these to determine the state of the air-fuel ratio.
- a fuel supply means for example, a spray-type fuel addition device
- an air pump is connected to the exhaust gas pipe 23, and the air-fuel ratio of the exhaust gas is measured using these to determine the state of the air-fuel ratio.
- the air-fuel ratio atmosphere of the exhaust gas brought into contact with the oxidation catalyst by introducing fuel or air into the exhaust gas in contact with the oxidation catalyst 23 according to the state of the air-fuel ratio is changed. Gosuru method and the like may be employed.
- oxidation catalyst of the present invention it is only necessary to include the oxidation catalyst, and other configurations are not particularly limited. In the embodiments shown in FIGS.
- the first control unit controls the lean gas supply process according to the amount of particulate matter deposited and the catalyst temperature. It is sufficient that the lean gas supply process and the rich gas supply process can be controlled alternately, and the control method is not limited to the above embodiment. Further, in the case of using the second control means, the control method is not particularly limited to the above-described embodiment, and when the estimated value of the ash accumulation amount exceeds the reference value, the empty space in the oxidation catalyst. Any method that can be controlled so as to perform the step of contacting the exhaust gas having a rich fuel ratio can be used as appropriate.
- Example 1 Preparation of oxidation catalyst> Ion exchange water is added to calcium sulfate hemihydrate (Yakigypsum, manufactured by Wako Pure Chemical Industries, Ltd.) and milled with a ball mill to obtain a slurry containing calcium sulfate particles having an average secondary particle size of 0.6 ⁇ m. Formed. Next, a commercially available DPF made of cordierite (diameter 30 mm, length 50 mm, porosity 60%, average pore diameter 30 ⁇ m, manufactured by NGK) is prepared so that the slurry enters the partition pores of the DPF. Was impregnated.
- silver sulfate aqueous solution was prepared by dissolving silver sulfate (manufactured by Wako Pure Chemical Industries, Ltd.) in 90 ° C. ion exchange water.
- the silver sulfate aqueous solution is impregnated so that the supported amount of silver sulfate per liter of DPF is 10.8 g / L so as to enter into the pores of the DPF on which calcium sulfate is supported. I let you.
- the DPF impregnated with the aqueous silver sulfate solution is dried at 110 ° C. for 16 hours, and then calcined at 300 ° C.
- the supported amount of silver sulfate per liter of DPF was 10.8 g / L.
- the supported amount of silver sulfate in terms of silver metal per liter of DPF is 7.5 g / L, and the supported amount of silver sulfate in terms of metal metal to 100 parts by mass of calcium sulfate (carrier) is 11.11. Part by mass.
- the thickness of the coating layer of the catalyst in which silver sulfate was supported on calcium sulfate supported (coated) on the partition walls of the DPF was 2 ⁇ m.
- ⁇ PM purification treatment (I)> Using an exhaust gas pipe in which an oxidation catalyst to which PM has been adhered by the PM adhesion treatment (I) is disposed, from the inlet (the opening into which the above-mentioned mixture of PM and air is introduced), the inlet gas temperature to the catalyst: 500 ° C., flow rate: by introducing N 2 gas for 15 minutes at 30L / min condition, after supplying N 2 gas to the oxidation catalyst, was subjected to treatment before cooling to room temperature (25 ° C.).
- model gas A having a lean atmosphere shown in Table 1 from the inlet of the exhaust gas pipe (model of a gas having a lean air-fuel ratio) is heated to 30 ° C. to 810 ° C. (entering the catalyst) at a heating rate of 20 ° C./min.
- the gas is introduced at a flow rate of 30 L / min while raising the temperature to the gas temperature), and the model gas A is brought into contact with the oxidation catalyst after the pretreatment, and then the outlet of the exhaust pipe (the other opening) Part)), the CO 2 and CO concentrations in the gas (outgoing gas) discharged are measured, the amount of oxidized PM is calculated from the concentration, and the total amount of PM adhering to the oxidation catalyst is the initial adhering amount.
- the oxidation performance was evaluated by determining the temperature (50% PM oxidation temperature) when the entering gas was oxidized when it became 50%.
- the results of the 50% PM oxidation temperature obtained are shown in FIG. It can be said that the lower the 50% PM oxidation temperature, the higher the PM oxidation performance (oxidation activity).
- ⁇ Ash deposition treatment> The exhaust gas from the actual engine (6 in-line cylinders) is supplied to the oxidation catalyst after the PM purification treatment (I) using JIS No. 2 fuel (sulfur content 5 to 7 ppm), and ash is removed. Deposited. That is, an actual engine (in-line 6 cylinder) is operated using JIS No. 2 fuel (sulfur content 5-7 ppm), exhaust gas from the engine is introduced from the entrance of the exhaust gas pipe, and the catalyst bed temperature of the oxidation catalyst is The temperature condition was adjusted to 500 ° C. (constant), and the exhaust gas was continuously supplied to the oxidation catalyst after the PM purification treatment (I) was performed for 500 hours.
- the exhaust gas supply process from such an actual engine is performed by removing the exhaust gas from the engine and removing 12 exhaust pipes (PM purification used in Examples 1 to 7 and Comparative Examples 1 to 5).
- the amount of ash deposited on each oxidation catalyst was 13 g / L, and the thickness of ash deposited on the DPF partition walls observed with a digital microscope was about 50 ⁇ m.
- ⁇ PM adhesion treatment (II)> The oxidation catalyst after the ash deposition process was subjected to a process for adhering PM using the same method as the PM adhesion process (I).
- the adhesion amount of PM was 2 g / L per 1 L of DPF capacity.
- Example 1 the preparation of the oxidation catalyst, the PM adhesion process (I), the PM purification process (I), the ash deposition process, the PM adhesion process (II), and the PM purification process (II) are sequentially performed. Then, after the ash deposition process and after the ash deposition process of the exhaust gas purification apparatus including the oxidation catalyst (in this embodiment, model gas A is modeled as exhaust gas and an oxidation catalyst is disposed in the flow path of the exhaust gas). Each 50% PM oxidation temperature was determined.
- Example 2 The oxidation catalyst is the same as in Example 1 except that the rich gas supply process described later is performed on the oxidation catalyst before the PM adhesion process (I) and the PM adhesion process (II).
- 50% PM oxidation before and after ash deposition of an exhaust gas purifying apparatus in this embodiment, model gases A and B are modeled as exhaust gas and an oxidation catalyst is disposed in the exhaust gas flow path
- Each temperature was determined.
- the preparation of the oxidation catalyst, the rich gas supply process, the PM adhesion process (I), the PM purification process (I), the ash deposition process, the rich gas supply process, the PM adhesion process (II), and the PM purification Each treatment was performed in the order of treatment (II).
- the results of the 50% PM oxidation temperature obtained are shown in FIG.
- the model gas B (a model of a gas having a rich air-fuel ratio) shown in Table 2 is supplied to the oxidation catalyst at a temperature of 400 ° C. (constant) and a flow rate of 30 L / min. For 12 minutes.
- Example 3 Ash deposition process of the exhaust gas purifying apparatus equipped with the oxidation catalyst in the same manner as in Example 2 except that the gas temperature of the model gas B entering the oxidation catalyst in the rich gas supply process is changed from 400 ° C. to 500 ° C.
- the 50% PM oxidation temperature before and after the ash deposition treatment was determined, respectively.
- the results of the 50% PM oxidation temperature obtained are shown in FIG.
- Example 4 Except for changing the supply time of the model gas B to the oxidation catalyst in the rich gas supply process from 12 minutes to 60 minutes, in the same manner as in Example 2, before the ash deposition process of the exhaust gas purification apparatus provided with the oxidation catalyst The 50% PM oxidation temperature after the ash deposition treatment was determined. The results of the 50% PM oxidation temperature obtained are shown in FIG.
- Example 5 ⁇ Preparation of oxidation catalyst> Ion exchange water was added to calcium phosphate (manufactured by Wako Pure Chemical Industries, Ltd.) and milled with a ball mill to form a slurry containing calcium phosphate particles having an average secondary particle size of 0.6 ⁇ m.
- a commercially available DPF made of cordierite (diameter 30 mm, length 50 mm, porosity 60%, average pore diameter 30 ⁇ m, manufactured by NGK) is prepared so that the slurry enters the partition pores of the DPF. Was impregnated.
- excess slurry was removed from the DPF impregnated with the slurry using a suction machine, dried at 110 ° C.
- silver sulfate aqueous solution was prepared by dissolving silver sulfate (manufactured by Wako Pure Chemical Industries, Ltd.) in 90 ° C. ion exchange water.
- the silver sulfate aqueous solution is impregnated so that the amount of silver sulfate supported per 1 L of DPF is 10.8 g / L so as to enter the pores of the partition walls of the DPF on which calcium phosphate is supported. It was.
- the DPF impregnated with the aqueous silver sulfate solution is dried at 110 ° C. for 16 hours, and then calcined at 300 ° C.
- the supported amount of silver sulfate per liter of DPF was 10.8 g / L.
- the amount of silver sulfate supported per liter of DPF in terms of silver (metal) is 7.5 g / L, and the amount of silver sulfate supported in terms of silver with respect to 100 parts by mass of calcium phosphate (carrier) is 11.11 mass.
- Example 5 Except for using the oxidation catalyst obtained as described above, in the same manner as in Example 1, the 50% PM oxidation temperature before and after the ash deposition treatment of the exhaust gas purification apparatus provided with the oxidation catalyst was respectively set. Asked. Thus, in Example 5, the preparation of the oxidation catalyst, the PM adhesion treatment (I), the PM purification treatment (I), the ash deposition treatment, the PM adhesion treatment (II), and the PM purification treatment (II) in this order. Processed. The results of the 50% PM oxidation temperature obtained are shown in FIG.
- Example 6 As the oxidation catalyst, the oxidation catalyst is provided in the same manner as in Example 2 except that an oxidation catalyst obtained by adopting the same method as the method of preparing the oxidation catalyst employed in Example 5 is used.
- the 50% PM oxidation temperature before and after the ash deposition process of the exhaust gas purification apparatus was determined.
- Example 6 the preparation of the oxidation catalyst, the rich gas supply process, the PM adhesion process (I), the PM purification process (I), the ash deposition process, the rich gas supply process, the PM adhesion process (II), and the PM purification
- Each treatment was performed in the order of treatment (II).
- the results of the 50% PM oxidation temperature obtained are shown in FIG.
- Example 7 Ash deposition process of the exhaust gas purifying apparatus equipped with the oxidation catalyst in the same manner as in Example 6 except that the gas temperature of the model gas B entering the oxidation catalyst in the rich gas supply process is changed from 400 ° C. to 500 ° C.
- the 50% PM oxidation temperature before and after the ash deposition treatment was determined, respectively.
- the results of the 50% PM oxidation temperature obtained are shown in FIG.
- Exhaust gas purification apparatus provided with a comparison oxidation catalyst in the same manner as in Example 1 except that the comparison oxidation catalyst (DPF supporting calcium phosphate) prepared in this way was used as the oxidation catalyst.
- the 50% PM oxidation temperature before and after the ash deposition process was determined. The results of the 50% PM oxidation temperature obtained are shown in FIG.
- an aqueous praseodymium nitrate solution in which hydrated praseodymium nitrate (III) (manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved was prepared.
- the aqueous praseodymium nitrate solution is impregnated so that the amount of Pr 6 O 11 supported per 1 L of DPF is 7.5 g / L so as to enter the pores of the DPF supporting the ceria. And calcined at 800 ° C. for 24 hours to obtain an oxidation catalyst for comparison.
- Pr 6 O 11 supported is 7.5 g / L per liter of DPF, but it is a complex oxide of ceria and praseodymium oxide (Ce 0.9 Pr 0.1 O 2 ) by firing at 800 ° C. Is presumed to have been formed.
- the comparative oxidation catalyst thus prepared (DPF carrying a composite oxide of ceria and praseodymium oxide) was used as the oxidation catalyst in the same manner as in Example 1 for comparison.
- the 50% PM oxidation temperature before and after the ash deposition process of the exhaust gas purification apparatus including the oxidation catalyst was determined.
- the results of the 50% PM oxidation temperature obtained are shown in FIG.
- the loading amount of the mixture of ceria and zirconia per liter of DPF is 67.5 g / L, and the loading amount of ceria and zirconia per liter of DPF is 20.3 g / L (ceria), It was 47.3 g / L (zirconia).
- silver nitrate aqueous solution was prepared by dissolving silver nitrate (manufactured by Toyo Chemical Co., Ltd.) in ion-exchanged water.
- the silver nitrate aqueous solution is introduced into the partition pores of the DPF supporting ceria and zirconia so that the amount of supported silver (metal) per liter of DPF is 7.5 g / L. It was impregnated and calcined at 500 ° C. for 5 hours, and silver was supported on ceria and zirconia supported (coated) on the partition walls of the DPF to produce an oxidation catalyst for comparison of the form supported on the DPF.
- the amount of silver supported per liter of DPF was 7.5 g / L.
- a comparative oxidation catalyst prepared in this manner (a DPF carrying a catalyst comprising ceria and zirconia carrying silver) was used as the oxidation catalyst in the same manner as in Example 1 except that The 50% PM oxidation temperature before and after the ash deposition process of the exhaust gas purifying apparatus provided with the oxidation catalyst for the above was determined. The results of the 50% PM oxidation temperature obtained are shown in FIG.
- silver nitrate manufactured by Toyo Kagaku Kogyo
- the silver nitrate aqueous solution has a silver (metal) loading amount of 7.5 g / L per 1 L of DPF capacity.
- impregnation so as to enter into the pores of the DPF on which the ceria and zirconia are supported, and firing at 500 ° C. for 5 hours to support silver on alumina supported (coated) on the DPF partitions.
- an oxidation catalyst for comparison of the form supported on the DPF was manufactured.
- the amount of silver supported per liter of DPF was 7.5 g / L.
- a comparative oxidation catalyst prepared in this manner (a DPF carrying a catalyst made of alumina carrying silver) was used as the oxidation catalyst in the same manner as in Example 1 for comparison.
- the 50% PM oxidation temperature before and after the ash deposition process of the exhaust gas purification apparatus including the oxidation catalyst was determined.
- the results of the 50% PM oxidation temperature obtained are shown in FIG.
- Examples 3 to 4 peaks of calcium sulfate and Ag (metal) were observed in the XRD pattern, and it was found that the component supported on the carrier (calcium sulfate) was only metallic silver. From these results, it was confirmed that metal-like silver can be deposited on the carrier by supplying rich gas. In Comparative Example 1, it was confirmed from the XRD pattern that only calcium sulfate was present.
- the PM oxidation of the exhaust gas purifying apparatus obtained in Examples 1 to 7 and the exhaust gas purifying apparatus obtained in Comparative Examples 1 and 2 before the ash deposition treatment was performed on the oxidation catalyst. Comparing the activities, the exhaust gas purifying apparatuses obtained in Examples 1 to 7 all had a 50% PM oxidation temperature lower than that of the exhaust gas purifying apparatuses obtained in Comparative Examples 1 and 2, and Comparative Examples 1 and 2 were obtained. It was found that the PM oxidation performance was superior to that of the obtained exhaust gas purification device. The present inventors infer that such a result is because PM oxidation activity is not expressed only by loading calcium sulfate or calcium phosphate on the DPF as in the exhaust gas purification apparatuses obtained in Comparative Examples 1 and 2.
- the exhaust gas purification apparatus obtained in Comparative Example 4 shows a relatively high PM oxidation activity, but the activity change due to ash deposition is large, and there is a large practical barrier. I found out. Further, in Comparative Example 4, the ash deposition thickness was set to 50 ⁇ m. However, when the ash deposition thickness is further increased during actual use, it is considered that the PM oxidation performance further decreases. Further, from the results shown in FIG. 5, it is confirmed that the exhaust gas purifying apparatus has a higher PM oxidation performance when the process of supplying the rich gas is performed (Examples 2 to 4, 6 to 7). It was done.
- the decrease in the oxidation performance of the particulate matter due to the ash deposition is sufficiently suppressed, and a sufficiently advanced particulate matter oxidation performance is exhibited even after the ash deposition. It is possible to provide an exhaust gas purifying apparatus capable of performing the above and an exhaust gas purifying method using the exhaust gas purifying apparatus.
- the exhaust gas purification apparatus and exhaust gas purification method of the present invention are particularly useful as an apparatus or method for purifying exhaust gas from, for example, a diesel engine.
Abstract
Description
前記酸化触媒が、Caの硫酸塩及びリン酸塩からなる群より選択される少なくとも1種の金属塩からなる担体と、該担体に担持された銀含有物質とを備える、ものである。
前記酸化触媒が、Caの硫酸塩及びリン酸塩からなる群より選択される少なくとも1種の金属塩からなる担体と、該担体に担持された銀含有物質とを備えるものである、方法である。
前記アッシュ堆積量推定手段により推定されるアッシュの堆積量が基準値を超えた場合に、前記酸化触媒に前記空燃比がリッチである排ガスを接触させる工程を実施することが好ましい。
(2) 4Ag+O2→4Ag++2O2-
[なお、このようなPM酸化処理1において起こる反応に関して、前記銀含有物質として銀(メタル)を単独で用いる場合には、高温のリーン雰囲気下において、反応式(2)によりAgイオンが形成されて反応が進行して、PMが除去される。]。
(4) 4Ag+O2→2Ag2O
(5) 2Ag2O+C(PM)→4Ag+CO2
[なお、このようなPM酸化処理2に関して、前記銀含有物質としてAg(メタル)を単独で用いる場合には、反応式(4)と(5)に示す反応によりPMが除去される。]。
前記酸化触媒が、Caの硫酸塩及びリン酸塩からなる群より選択される少なくとも1種の金属塩からなる担体と、該担体に担持された銀含有物質とを備えるものである。
前記酸化触媒が、Caの硫酸塩及びリン酸塩からなる群より選択される少なくとも1種の金属塩からなる担体と、該担体に担持された銀含有物質とを備えるものである、方法である。
〈酸化触媒の調製〉
硫酸カルシウム0.5水和物(焼き石膏、和光純薬工業製)にイオン交換水を加え、ボールミルでミリングして、平均二次粒子径が0.6μmの硫酸カルシウムの粒子を含有するスラリーを形成した。次に、コージェライト製の市販のDPF(直径30mm、長さ50mm、気孔率60%、平均細孔径30μm、日本ガイシ社製)を準備し、前記スラリーを前記DPFの隔壁細孔内に入り込むように含浸させた。次いで、前記スラリーを含浸させたDPFから、吸引機を用いて余分なスラリーを除去し、110℃で16時間乾燥した後、500℃で3時間焼成した。このような焼成により、前記硫酸カルシウム0.5水和物を硫酸カルシウム(無水物)に変更でき、これにより硫酸カルシウム(無水物)をDPFに強く担持(付着)させることができた。このようにして硫酸カルシウム(無水物)をDPFに担持したところ、DPFの容量1Lあたりの硫酸カルシウムの担持量(コート量)は67.5g/Lであった。
前記酸化触媒を石英ガラス製の排ガス管(内径:30mm、長さ1000mm)の中心部に配置した後、その排ガス管の一方の開口部(以下、「入り口」という。)から内部に向かって、燃焼粒子発生器(Combustion Aerosol Standard; CAST、Matter Engineering社製)を用いて発生させた粒子状物質(PM)を、室温(25℃)の空気と一緒に導入し、室温(25℃)条件下で、PMと空気の混合物を前記酸化触媒に接触させることによって前記酸化触媒にPMを付着させた(PM付着処理(I))。なお、このようなPM付着処理においては、前記酸化触媒に対する空気の流量が20L/分となるようにした。また、このようなPM付着処理による前記酸化触媒へのPMの付着量はDPFの容量1Lあたり2g/Lであった。
前記PM付着処理(I)によりPMを付着させた酸化触媒が配置された排ガス管を用い、その入り口(前述のPMと空気の混合物を導入した開口部)から、触媒への入ガス温度:500℃、流量:30L/分の条件でN2ガスを15分間導入して、N2ガスを前記酸化触媒に供給した後、室温(25℃)まで冷却する前処理を行った。
前記PM浄化処理(I)を施した後の前記酸化触媒に対して、JIS2号燃料(硫黄分5~7ppm)を使用して実エンジン(直列6気筒)からの排ガスを供給して、アッシュを堆積させた。すなわち、JIS2号燃料(硫黄分5~7ppm)を使用して実エンジン(直列6気筒)を運転させて、そのエンジンからの排ガスを前記排ガス管の入り口から導入し、酸化触媒の触媒床温度が500℃(一定)となるように温度条件を調整して、PM浄化処理(I)を施した後の前記酸化触媒に対して排ガスを500時間継続して供給した。なお、このような実エンジン(直列6気筒)からの排ガスの供給工程は、該エンジンからの排ガスを取り出して12本の排ガス管(実施例1~7及び比較例1~5で用いたPM浄化処理(I)後の酸化触媒を配置した排ガス管:実施例2~7及び比較例1~5については後述する。)に対して、同じ条件で同じ排ガスが流入するようにして行った。このような排ガスの供給の結果、各酸化触媒へのアッシュの堆積量はいずれも13g/Lであり、デジタルマイクロスコープで観察したDPF隔壁上のアッシュ堆積厚さはいずれも約50μmであった。
前記アッシュ堆積処理後の酸化触媒に対して、PM付着処理(I)と同様の方法を採用してPMを付着させる処理を行った。なお、PMの付着量はDPFの容量1Lあたり2g/Lであった。
前記PM浄化処理(I)を施した後の前記酸化触媒を用いてPM浄化処理(I)と同様の方法を採用してPMを浄化せしめて、50%PM酸化温度を求めた。得られた50%PM酸化温度の結果を図5に示す。
後述のリッチガス供給処理を、前記PM付着処理(I)及び前記PM付着処理(II)を実施する前の酸化触媒に対して、それぞれ施した以外は、実施例1と同様にして、前記酸化触媒を備える排ガス浄化装置(本実施例においてはモデルガスA及びBを排ガスと模して、排ガスの流路に酸化触媒を配置したもの)のアッシュ堆積処理前及びアッシュ堆積処理後の50%PM酸化温度をそれぞれ求めた。このように、実施例2においては、酸化触媒の調製、リッチガス供給処理、PM付着処理(I)、PM浄化処理(I)、アッシュ堆積処理、リッチガス供給処理、PM付着処理(II)、PM浄化処理(II)の順で各処理を行った。得られた50%PM酸化温度の結果を図5に示す。
表2に示すリッチ雰囲気のモデルガスB(空燃比がリッチであるガスのモデル)を、酸化触媒への入りガス温度:400℃(一定)、流量:30L/分の条件で前記酸化触媒に対して12分間供給した。
前記リッチガス供給処理におけるモデルガスBの酸化触媒への入りガス温度をいずれも400℃から500℃に変更した以外は、実施例2と同様にして、前記酸化触媒を備える排ガス浄化装置のアッシュ堆積処理前及びアッシュ堆積処理後の50%PM酸化温度をそれぞれ求めた。得られた50%PM酸化温度の結果を図5に示す。
前記リッチガス供給処理におけるモデルガスBの酸化触媒への供給時間をいずれも12分間から60分間に変更した以外は、実施例2と同様にして、前記酸化触媒を備える排ガス浄化装置のアッシュ堆積処理前及びアッシュ堆積処理後の50%PM酸化温度をそれぞれ求めた。得られた50%PM酸化温度の結果を図5に示す。
〈酸化触媒の調製〉
リン酸カルシウム(和光純薬工業製)にイオン交換水を加え、ボールミルでミリングして、平均二次粒子径が0.6μmのリン酸カルシウムの粒子を含有するスラリーを形成した。次に、コージェライト製の市販のDPF(直径30mm、長さ50mm、気孔率60%、平均細孔径30μm、日本ガイシ社製)を準備し、前記スラリーを前記DPFの隔壁細孔内に入り込むように含浸させた。次いで、前記スラリーを含浸させたDPFから、吸引機を用いて余分なスラリーを除去し、110℃で16時間乾燥した後、500℃で3時間焼成した。このような焼成により、リン酸カルシウムをDPFに強く担持(付着)させることができた。このようにしてリン酸カルシウムをDPFに担持したところ、DPFの容量1Lあたりのリン酸カルシウムの担持量(コート量)は67.5g/Lであった。得られた50%PM酸化温度の結果を図5に示す。
酸化触媒として、実施例5で採用している酸化触媒の調製の方法と同様の方法を採用して得られた酸化触媒を用いた以外は、実施例2と同様にして、前記酸化触媒を備える排ガス浄化装置のアッシュ堆積処理前及びアッシュ堆積処理後の50%PM酸化温度をそれぞれ求めた。このように、実施例6においては、酸化触媒の調製、リッチガス供給処理、PM付着処理(I)、PM浄化処理(I)、アッシュ堆積処理、リッチガス供給処理、PM付着処理(II)、PM浄化処理(II)の順で各処理を行った。得られた50%PM酸化温度の結果を図5に示す。
前記リッチガス供給処理におけるモデルガスBの酸化触媒への入りガス温度をいずれも400℃から500℃に変更した以外は、実施例6と同様にして、前記酸化触媒を備える排ガス浄化装置のアッシュ堆積処理前及びアッシュ堆積処理後の50%PM酸化温度をそれぞれ求めた。得られた50%PM酸化温度の結果を図5に示す。
酸化触媒の調製に際して硫酸銀の担持を行わず、硫酸カルシウム(無水物)を担持したDPF(硫酸カルシウムの担持量(コート量):67.5g/L、比較のための酸化触媒)をそのまま前記酸化触媒として利用した以外は、実施例1と同様にして、比較のための酸化触媒を備える排ガス浄化装置のアッシュ堆積処理前及びアッシュ堆積処理後の50%PM酸化温度をそれぞれ求めた。得られた50%PM酸化温度の結果を図5に示す。
〈触媒の調製〉
酸化触媒の調製に際して硫酸銀の担持を行わなかった以外は実施例5で採用している酸化触媒の調製工程と同様にして、リン酸カルシウムを担持したDPF(リン酸カルシウムの担持量(コート量):67.5g/L、比較のための酸化触媒)を得た。
〈触媒の調製〉
先ず、実施例1の酸化触媒の調製の際に用いたDPFと同様のDPFを準備した。次に、セリアゾル(多木化学製の商品名「ニードラールU-15」)を、前記DPFの隔壁細孔内に入り込むように含浸させた(含浸工程)。次に、前記ゾルを含浸させたDPFから、吸引機で余分なゾルを除去し、大気中、250℃で1時間の焼成した(焼成工程)。このような含浸工程及び焼成工程を、DPFの容量1Lあたりのセリアの担持量が67.5g/Lとなるまで繰り返し実施し、セリアが担持されたDPFを得た。次に、硝酸プラセオジム(III)の水和物(和光純薬工業製)を溶解した硝酸プラセオジム水溶液を調製した。次いで、前記硝酸プラセオジム水溶液を、DPFの容量1LあたりのPr6O11の担持量が7.5g/Lとなるようにして、前記セリアが担持されたDPFの隔壁細孔内に入り込むように含浸させ、800℃で24時間焼成し、比較のための酸化触媒を得た。なお、Pr6O11担持量はDPFの容量1Lあたり7.5g/Lであるが、800℃での焼成によりセリアと酸化プラセオジムとの複合酸化物(Ce0.9Pr0.1O2)が形成されたものと推察される。
〈触媒の調製〉
先ず、実施例1の酸化触媒の調製の際に用いたDPFと同様のDPFを準備した。次に、セリアゾル(多木化学製の商品名「ニードラールU-15」)及びジルコニアゾル(第一稀元素化学工業製、酢酸ジルコニール)を、固形分のセリアとジルコニアの質量比(セリア:ジルコニア)が30:70となるようにして混合して混合液を調製した。次いで、前記混合液を前記DPFの隔壁細孔内に入り込むように含浸させた(含浸工程)。次に、前記混合液を含浸させたDPFから、吸引機で余分な混合液を除去し、大気中、250℃で1時間の焼成した(焼成工程)。このような含浸工程及び焼成工程を、DPFの容量1Lあたりのセリア及びジルコニアの混合物の担持量が67.5g/Lとなるまで繰り返し実施した後、700℃で5時間焼成して、セリア及びジルコニアが担持されたDPFを得た。なお、DPFの容量1Lあたりのセリア及びジルコニアの混合物の担持量は67.5g/Lであり、DPFの容量1Lあたりのセリアとジルコニアのそれぞれの担持量は、20.3g/L(セリア)、47.3g/L(ジルコニア)であった。
〈触媒の調製〉
先ず、実施例1の酸化触媒の調製の際に用いたDPFと同様のDPFを準備した。次に、アルミナゾル(日産化学社製の商品名「A520」)を前記DPFの隔壁細孔内に入り込むように含浸させた(含浸工程)。次に、前記混合液を含浸させたDPFから、吸引機で余分な混合液を除去し、大気中、250℃で1時間の焼成した(焼成工程)。このような含浸工程及び焼成工程を、DPFの容量1Lあたりのアルミナの担持量が30g/Lとなるまで繰り返し実施した後、700℃で5時間焼成して、アルミナが担持されたDPFを得た。なお、DPFの容量1Lあたりのアルミナの混合物の担持量は30g/Lであった。
〈X線回折(XRD)測定〉
実施例1~4及び比較例1において、アッシュ堆積処理を実施する前の段階の各酸化触媒のDPFの触媒の担持(コート)層から粉末状の試料をそれぞれ取り出し、各試料に対してX線回折(XRD)測定を行った。このようなXRD測定により得られたXRDパターンを図6に示す。なお、図6中、記号の丸(○)は丸記号が付された位置のピークがAg(メタル)に由来するXRDピークであることを示し、三角(△)は三角記号が付された位置のピークがAg2SO4に由来するXRDピークであることを示す。
図5に示す各排ガス浄化装置のアッシュ堆積処理前及びアッシュ堆積処理後の50%PM酸化温度の結果に基づいて、各排ガス浄化装置の触媒性能を評価した。
Claims (11)
- 内燃機関からの排ガスに含まれる粒子状物質を酸化して浄化するための酸化触媒を備える排ガス浄化装置であって、
前記酸化触媒が、Caの硫酸塩及びリン酸塩からなる群より選択される少なくとも1種の金属塩からなる担体と、該担体に担持された銀含有物質とを備える、排ガス浄化装置。 - 前記銀含有物質が、銀、酸化銀、炭酸銀、硫酸銀及びリン酸銀からなる群より選択される少なくとも1種である、請求項1に記載の排ガス浄化装置。
- 前記酸化触媒が、前記担体と前記銀含有物質とを備える触媒をパティキュレートフィルタ上に担持したものである、請求項1又は2に記載の排ガス浄化装置。
- 前記酸化触媒に空燃比がリーンである排ガスを接触させる工程と、前記酸化触媒に前記空燃比がリッチである排ガスを接触させる工程とを交互に実施するように制御する第一制御手段を更に備える、請求項1~3のうちのいずれか一項に記載の排ガス浄化装置。
- 前記酸化触媒に堆積された前記排ガス中のアッシュの量を推定するアッシュ堆積量推定手段を更に備える、請求項1~4のうちのいずれか一項に記載の排ガス浄化装置。
- 前記アッシュ堆積量推定手段により推定されるアッシュの堆積量が基準値を超えた場合に、前記酸化触媒に前記空燃比がリッチである排ガスを接触させる工程を実施するように制御する第二制御手段を更に備える、請求項5に記載の排ガス浄化装置。
- 内燃機関からの排ガスに含まれる粒子状物質を酸化して浄化するための酸化触媒を備える排ガス浄化装置を用いて該酸化触媒に排ガスを接触させることにより前記粒子状物質を浄化する排ガス浄化方法であって、
前記酸化触媒が、Caの硫酸塩及びリン酸塩からなる群より選択される少なくとも1種の金属塩からなる担体と、該担体に担持された銀含有物質とを備えるものである、排ガス浄化方法。 - 前記銀含有物質が、銀、酸化銀、炭酸銀、硫酸銀及びリン酸銀からなる群より選択される少なくとも1種である、請求項7に記載の排ガス浄化方法。
- 前記酸化触媒が、前記担体と前記銀含有物質とを備える触媒をパティキュレートフィルタ上に担持したものである、請求項7又は8に記載の排ガス浄化方法。
- 前記酸化触媒に空燃比がリーンである排ガスを接触させる工程と、前記酸化触媒に前記空燃比がリッチである排ガスを接触させる工程とを交互に実施する、請求項7~9のうちのいずれか一項に記載の排ガス浄化方法。
- 前記排ガス浄化装置が、前記酸化触媒に堆積された前記排ガス中のアッシュの量を推定するアッシュ堆積量推定手段を更に備えたものであり、且つ、
前記アッシュ堆積量推定手段により推定されるアッシュの堆積量が基準値を超えた場合に、前記酸化触媒に前記空燃比がリッチである排ガスを接触させる工程を実施する、請求項7~10のうちのいずれか一項に記載の排ガス浄化方法。
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JP5956496B2 (ja) * | 2014-04-02 | 2016-07-27 | 株式会社豊田中央研究所 | 排ガス浄化用触媒、それを用いた排ガス浄化フィルタ及び排ガス浄化方法 |
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JP6394616B2 (ja) * | 2016-01-22 | 2018-09-26 | トヨタ自動車株式会社 | 内燃機関の排気浄化装置 |
JP6588359B2 (ja) * | 2016-02-25 | 2019-10-09 | 株式会社豊田自動織機 | 内燃機関の排気浄化装置 |
DE102017125406A1 (de) * | 2017-10-30 | 2019-05-02 | Volkswagen Aktiengesellschaft | Verfahren zum Betrieb einer Abgasanlage |
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Also Published As
Publication number | Publication date |
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EP2696047A1 (en) | 2014-02-12 |
KR101506108B1 (ko) | 2015-03-25 |
AU2012239283B2 (en) | 2015-07-30 |
AU2012239283A1 (en) | 2013-11-21 |
BR112013025822B1 (pt) | 2021-07-20 |
EP2696047A4 (en) | 2014-10-01 |
BR112013025822A2 (pt) | 2016-12-20 |
KR20130137024A (ko) | 2013-12-13 |
EP2696047B1 (en) | 2018-08-01 |
JP5649503B2 (ja) | 2015-01-07 |
CN103459790B (zh) | 2016-06-29 |
CN103459790A (zh) | 2013-12-18 |
JP2012219715A (ja) | 2012-11-12 |
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