WO2019059032A1 - Filtre de purification de gaz d'échappement - Google Patents

Filtre de purification de gaz d'échappement Download PDF

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Publication number
WO2019059032A1
WO2019059032A1 PCT/JP2018/033529 JP2018033529W WO2019059032A1 WO 2019059032 A1 WO2019059032 A1 WO 2019059032A1 JP 2018033529 W JP2018033529 W JP 2018033529W WO 2019059032 A1 WO2019059032 A1 WO 2019059032A1
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Prior art keywords
exhaust gas
catalyst
combustion
catalyst layer
nox reduction
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PCT/JP2018/033529
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English (en)
Japanese (ja)
Inventor
知弘 足立
一樹 白田
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パナソニックＩｐマネジメント株式会社
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Publication of WO2019059032A1 publication Critical patent/WO2019059032A1/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/86—Catalytic processes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/86—Catalytic processes
    • B01D53/90—Injecting reactants
    • 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
    • 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
    • B01J23/16—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
    • B01J23/20—Vanadium, niobium or tantalum
    • B01J23/22—Vanadium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/50—Catalysts, in general, characterised by their form or physical properties characterised by their shape or configuration
    • B01J35/56—Foraminous structures having flow-through passages or channels, e.g. grids or three-dimensional monoliths
    • 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
    • F01N3/02—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust
    • F01N3/021—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
    • F01N3/022—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 characterised by specially adapted filtering structure, e.g. honeycomb, mesh or fibrous
    • 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
    • F01N3/02—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust
    • F01N3/021—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
    • F01N3/033—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
    • 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
    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D46/00—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours
    • B01D46/42—Auxiliary equipment or operation thereof

Definitions

  • the present invention relates to an exhaust gas purification filter used to purify the exhaust gas of an internal combustion engine such as a diesel engine.
  • PM Particulate Matter
  • NOx nitrogen oxides
  • DPF heat-resistant exhaust gas purification filter
  • the DPF collects PM.
  • pressure loss increases as PM is collected. Therefore, when the pressure loss of the DPF rises, it is necessary to regenerate the DPF.
  • the DPF is heated by a burner or a heater to burn the deposited PM, convert it to carbon dioxide gas, and release it to the outside.
  • the catalyst is supported on the DPF, and the PM is burned by the catalytic action.
  • the combustion operation by a burner or a heater can be reduced.
  • the PM combustion catalyst is supported in advance on the DPF made of heat resistant ceramic, it is possible to carry out the combustion reaction as well as the PM collection.
  • platinum group metals such as platinum and palladium are widely used as PM combustion catalysts.
  • the method of removing NOx is to perform selective catalytic reduction (SCR) using a reducing agent.
  • SCR selective catalytic reduction
  • an SCR filter in which a NOx reduction and removal catalyst is supported on a filter base made of a ceramic honeycomb, and ammonia as a reducing agent are used.
  • ammonia reduces NOx contained in the exhaust gas and converts it to nitrogen. That is, NOx is removed from the exhaust gas that has passed through the SCR filter.
  • Urea water is generally used as a source of ammonia. Urea water can be supplied upstream of the SCR filter to hydrolyze urea in the exhaust gas to produce ammonia.
  • diesel engine exhaust gas purification systems often include a DPF having a function of collecting PM and an SCR filter having a function of purifying NOx separately as described above (for example, refer to Patent Document 1).
  • a platinum group metal used as a PM combustion catalyst has a strong oxidizing action, and thus oxidizes ammonia.
  • SCRF even if ammonia is supplied from the upstream side, the function of reducing and removing NOx is impaired by the platinum group metal used for the PM combustion catalyst.
  • an object of the present invention is to provide an exhaust gas purification filter having high PM combustion performance that can be burned at a lower temperature and NOx reduction performance in one filter substrate.
  • the present invention comprises a porous filter base having a plurality of cells partitioned by cell walls, a PM combustion catalyst which burns and purifies PM, and an NOx reduction and removal catalyst which reduces and purifies NOx.
  • the PM combustion catalyst forms a PM combustion catalyst layer included in part or all of the surface of the cell wall on the side where the exhaust gas flows.
  • the NOx reduction and removal catalyst forms a NOx reduction catalyst layer contained in part or all of the surface of the cell wall on the side where the exhaust gas flows out.
  • the PM combustion catalyst is a molten salt type catalyst including a composite oxide of cesium and vanadium in which the molar ratio of cesium to vanadium (Cs / V) is 0.5 ⁇ Cs / V ⁇ 1.5.
  • the molten salt type catalyst containing a composite oxide of cesium and vanadium is a direct oxidation type catalyst that burns PM using oxygen in the gas phase.
  • the molten salt catalyst melts in the vicinity of the reaction temperature with PM and becomes a liquid phase. Therefore, in the combustion of PM involving catalyst (solid) -PM (solid) -oxygen (gas), when the catalyst becomes a liquid phase, the contact with PM increases dramatically, and high PM combustion performance is expressed. It is considered.
  • the composite oxide of cesium and vanadium is characterized in that the interaction with ammonia acting as a reducing agent in the NOx reduction reaction is weak. Therefore, in a temperature range where the exhaust gas temperature is relatively low, ammonia can be supplied to the NOx reduction catalyst layer located downstream of the exhaust gas flow without being oxidized, and NOx reduction performance can be exhibited.
  • FIG. 1 is a cross-sectional view showing a part of an exhaust gas purification filter according to a first embodiment of the present invention.
  • FIG. 2 is a cross-sectional view showing a part of an exhaust gas purification filter according to a second embodiment of the present invention.
  • the exhaust gas purification filter 1 is provided, for example, in an exhaust passage (not shown) of an internal combustion engine such as a diesel engine, and collects particulate matter (hereinafter referred to as PM) in exhaust gas. It is a thing.
  • a reducing agent supply device (not shown) can be disposed on the upstream side of the exhaust gas purification filter 1.
  • the exhaust gas purification filter 1 has a porous filter base 4 having a plurality of cells 3 partitioned by cell walls 2, a PM combustion catalyst layer 5 including a PM combustion catalyst for burning and purifying PM, and NOx. And the NOx reduction catalyst layer 6 including the NOx reduction removal catalyst to be purified.
  • the filter substrate 4 is a wall flow type structure. That is, a plurality of cells 3 partitioned by the cell walls 2 are provided, and the end portions of adjacent cells 3 are alternately sealed. Thus, two types of cells 3 are adjacent to each other via the cell wall 2. The first is the exhaust gas inflow side cell 3 which is open at the upstream side of the exhaust gas and the downstream side is closed. The second is the exhaust gas outlet side cell 3 in which the upstream side of the exhaust gas is blocked and the downstream side is open.
  • the PM combustion catalyst layer 5 is provided on the entire surface of the cell wall 2 on the side where the exhaust gas flows. Further, the NOx reduction catalyst layer 6 is provided on the entire surface of the cell wall 2 on the exhaust gas outflow side.
  • the exhaust gas purification filter 1 has the PM combustion catalyst layer 5 disposed on the upstream side and the NOx reduction catalyst layer 6 disposed on the downstream side across the cell wall 2.
  • the exhaust gas purification filter 1 can circulate the exhaust gas through the pores provided in the cell wall 2 of the filter substrate 4.
  • the exhaust gas contains harmful substances such as PM and NOx.
  • PM is collected by the inside and the surface of the cell wall 2 on the side where the exhaust gas flows in, and further by the PM combustion catalyst layer 5.
  • the NOx in the exhaust gas moves to the downstream side of the filter substrate 4 through the pores of the cell wall 2.
  • a reducing agent such as ammonia
  • NOx is reduced and removed by the NOx reduction catalyst contained in the NOx reduction catalyst layer 6.
  • PM in the collected exhaust gas is burned and removed promptly by the PM combustion catalyst contained in the PM combustion catalyst layer 5.
  • the exhaust gas purification filter 1 of the present embodiment particularly has the following configuration.
  • the material of the filter substrate 4 may be a porous material made of heat-resistant ceramic, metal material or the like.
  • heat resistant ceramics silicon carbide (SiC), cordierite, silicon nitride, aluminum titanate etc. can be used, for example.
  • metal material for example, a stainless alloy, an Fe-Cr-Al alloy or the like can be used.
  • silicon carbide or cordierite is preferable from the viewpoint of heat resistance and catalyst coatability.
  • the average pore diameter of the pores provided in the cell wall 2 is not particularly limited. For example, by setting the average pore diameter to 5 ⁇ m to 50 ⁇ m, it is possible to efficiently collect PM while suppressing an excessive increase in pressure loss at the time of PM deposition.
  • the cross-sectional shape of the cell 3 is not particularly limited. From the viewpoint of increasing the contact area between the catalyst and PM, it is preferable to use any one of four to octagonal shapes.
  • the formation density of the cells 3 is not particularly limited.
  • the number of cells 3 is preferably 200 to 400 cells per square inch from the viewpoint that the contact area between the catalyst and PM can be increased. By setting the number of cells to 200 cells or more, the contact area between the catalyst and PM can be sufficiently secured. Further, by setting the number of cells to 400 cells or less, clogging due to PM deposition on the cells 3 can be less likely to occur.
  • the PM combustion catalyst of the present embodiment is a molten salt type catalyst including a composite oxide of cesium and vanadium (hereinafter, described as a Cs-V composite oxide).
  • the molar ratio of cesium to vanadium (Cs / V) is 0.5 ⁇ Cs / V ⁇ 1.5.
  • the molten salt type catalyst containing the Cs-V complex oxide is a direct oxidation type catalyst that burns PM using oxygen in the gas phase.
  • the molten salt catalyst melts in the vicinity of the reaction temperature with PM and becomes a liquid phase.
  • the catalyst in the combustion of PM involving catalyst (solid)-PM (solid)-oxygen (gas), the catalyst is in a liquid phase, the contact with PM is dramatically increased, and PM combustion in a low temperature range It can be performed. From the above, it is considered that the molten salt type catalyst containing the Cs-V complex oxide exhibits high PM combustion performance.
  • the PM combustion catalyst preferably includes a carrier for holding the Cs-V complex oxide.
  • the Cs-V complex oxide alone has high PM flammability, there is a concern that the contact ratio between PM and the catalyst is lowered due to the low specific surface area of the catalyst, and the combustion reaction is unlikely to occur.
  • the carrier when the carrier is not used, there is a concern that aggregation easily occurs under the influence of temperature and composition fluctuation of the exhaust gas, and PM combustion activity decreases. Therefore, by holding the Cs-V complex oxide in contact with the surface of the carrier, the specific surface area of the Cs-V complex oxide can be increased to suppress aggregation in a high temperature atmosphere.
  • the carrier for example, Al 2 O 3 , SiO 2 , TiO 2 , CeO 2 , ZrO 2 , CeO 2 -ZrO 2 , MgO or the like can be used.
  • the thickness of the PM combustion catalyst layer 5 is preferably 10 ⁇ m or more and 50 ⁇ m or less.
  • the thickness of the PM combustion catalyst layer 5 is preferably 10 ⁇ m or more and 50 ⁇ m or less.
  • the PM combustion catalyst layer 5 is provided on the entire surface of the cell wall 2 on the side where the exhaust gas flows, but may be provided on a part of the surface. In the case of providing them all, although the entire area of the surface of the cell wall 2 can be catalyzed, it may cause an increase in pressure loss. Therefore, the PM combustion performance of the exhaust gas purification filter 1 and the pressure can be reduced by making the length of the PM combustion catalyst layer 5 shorter than the length (depth) of the cell 3 and providing it on a part of the surface of the cell wall 2 It is preferable to adjust the balance of losses.
  • a part of the PM combustion catalyst may enter into the cell wall 2. Thereby, the combustion of PM collected deep in the cell wall 2 can be promoted.
  • pressure loss increases, so it is necessary to adjust the amount of PM combustion catalyst that enters inside.
  • the Cs-V complex oxide can promote the PM combustion reaction utilizing oxygen in the gas phase in a temperature range lower than that in the case of using a platinum group metal. That is, it can be said that high PM combustion performance is exhibited.
  • zeolite containing a base metal component selected from one or more of V 2 O 5 -TiO 2 -WO 3 , TiO 2 -WO 3 , copper and iron components can be used.
  • zeolite containing a copper component is preferable from the viewpoint of NOx reduction performance and heat resistance.
  • the NOx reduction catalyst layer 6 is provided on the entire surface of the cell wall 2 on the side where the exhaust gas flows out, but may be provided on part of the surface. In the case of providing them all, although the entire area of the surface of the cell wall 2 can be catalyzed, it may cause an increase in pressure loss.
  • the NOx reduction performance of the exhaust gas purification filter 1 and the pressure loss You can also adjust the balance.
  • a part of the NOx reduction catalyst may enter into the cell wall 2.
  • the reduction of NOx can be promoted.
  • a large amount of the NOx reduction catalyst enters the inside of the cell wall 2, this causes an increase in pressure loss, so it is necessary to adjust the amount of the NOx reduction catalyst introduced inside.
  • the NOx in the exhaust gas flowing into the exhaust gas purification filter 1 moves to the downstream side of the filter substrate 4 through the pores of the cell wall 2 together with the reducing agent (ammonia) supplied from the upstream side of the exhaust gas purification filter 1.
  • the NOx in the exhaust gas having moved to the downstream side of the filter substrate 4 is reduced and removed by the NOx reduction catalyst contained in the NOx reduction catalyst layer 6 provided on the surface of the cell wall 2 on the exhaust gas outflow side.
  • the collected PM is oxygen in the gas phase at a temperature range lower than that in the case of using a platinum group metal by the catalytic action of the Cs-V complex oxide contained in the PM combustion catalyst layer 5 at the time of filter regeneration treatment. React with it and burn off quickly.
  • the exhaust gas purification filter 1 is, as shown in FIG. 2, a porous filter base 4 having a plurality of cells 3 partitioned by cell walls 2 and a particulate matter combustion catalyst for burning and purifying particulate matter.
  • a PM combustion catalyst layer 5 that is a first catalyst layer that includes the catalyst and a NOx reduction catalyst layer 6 that is a second catalyst layer that includes a NOx reduction catalyst that reduces and purifies NOx are provided.
  • the PM combustion catalyst layer 5 is provided on part or all of the surface of the cell wall 2 on the side where the exhaust gas flows. Further, the NOx reduction catalyst layer 6 is provided on part or all of the surface of the cell wall 2 on the side where the exhaust gas flows out.
  • the exhaust gas purification filter 1 can circulate the exhaust gas through the pores provided in the cell wall 2 of the filter substrate 4.
  • the exhaust gas contains harmful substances such as particulate matter and NOx. Among them, particulate matter is collected by the inside and the surface of the cell wall 2 and further by the PM combustion catalyst layer 5. Further, NOx in the exhaust gas moves to the downstream side of the filter base 4 through the pores of the cell wall 2.
  • the reducing agent such as ammonia is supplied from the upstream side of the exhaust gas purification filter 1 to make the NOx reduction catalyst contained in the NOx reduction catalyst layer 6 work to reduce and remove it.
  • the reducing agent such as ammonia
  • the particulate matter in the exhaust gas collected in the PM combustion catalyst layer 5 is promptly burned and removed by the particulate matter combustion catalyst contained in the PM combustion catalyst layer 5.
  • the exhaust gas purification filter 1 of the present embodiment particularly has the following configuration.
  • the filter substrate 4 has a wall flow type structure, and includes a plurality of cells 3 partitioned by the cell walls 2, and the end portions of adjacent cells are alternately sealed. Thus, two types of cells 3 are adjacent to each other via the cell wall 2.
  • the first is an exhaust gas inflow cell in which the upstream side of the exhaust gas is opened as the inlet 7 and the downstream side is closed to form the back 8.
  • the second is an exhaust gas outflow cell in which the upstream side of the exhaust gas is closed to form a back 9 and the downstream side is opened as the outlet 10.
  • the material of the filter substrate 4 may be a porous material made of heat-resistant ceramic, metal material or the like.
  • heat resistant ceramics silicon carbide (SiC), cordierite, silicon nitride, aluminum titanate etc. can be used, for example.
  • metal material for example, a stainless alloy, an Fe-Cr-Al alloy or the like can be used.
  • silicon carbide is preferable from the viewpoint of heat resistance and catalyst coatability.
  • the average pore diameter of the pores provided in the cell wall 2 is not particularly limited, but can be, for example, 5 ⁇ m to 50 ⁇ m. When the average pore size is 5 ⁇ m or more, an excessive increase in pressure loss can be suppressed even if particulate matter is deposited.
  • the cross-sectional shape of the cell 3 is not particularly limited, but is preferably any one of four to octagonal from the viewpoint that the contact area between the catalyst and the particulate matter can be increased.
  • the formation density of the cells 3 is not particularly limited, but the number of the cells 3 is preferably 200 to 400 cells per square inch from the viewpoint that the contact area between the catalyst and the particulate matter can be increased as described above. .
  • the number of cells is preferably 200 to 400 cells per square inch from the viewpoint that the contact area between the catalyst and the particulate matter can be increased as described above. .
  • the number of cells By setting the number of cells to 200 cells or more, the contact area between the catalyst and the particulate matter can be sufficiently secured.
  • the number of cells to 400 cells or less, clogging due to particulate matter deposition on the cells 3 can be less likely to occur.
  • the particulate matter combustion catalyst of the present embodiment is a molten salt type catalyst including a composite oxide of cesium and vanadium (hereinafter, described as a Cs-V composite oxide).
  • the molar ratio of cesium to vanadium (Cs / V) is 0.5 ⁇ Cs / V ⁇ 1.5.
  • the molten salt type catalyst containing the Cs-V complex oxide is a direct oxidation type catalyst that burns particulate matter using oxygen in the gas phase.
  • the molten salt catalyst melts in the vicinity of the reaction temperature with the particulate matter to form a liquid phase.
  • the particulate matter combustion catalyst preferably includes a carrier for retaining the Cs-V complex oxide.
  • Cs-V complex oxide alone has high particulate matter combustibility, the contact ratio between particulate matter and catalyst decreases due to the low specific surface area of the catalyst, which may make it difficult to cause a combustion reaction. is there.
  • the carrier in the case where the carrier is not used, there is a risk that aggregation may be easily performed and particulate matter combustion activity may be reduced under the influence of temperature and composition fluctuations of the exhaust gas. Therefore, by bringing the Cs-V complex oxide into contact with the surface of the carrier and holding it, aggregation in a high temperature atmosphere can be suppressed while increasing the specific surface area of the Cs-V complex oxide.
  • the carrier for example, Al 2 O 3 , SiO 2 , TiO 2 , CeO 2 , ZrO 2 , CeO 2 -ZrO 2 , MgO or the like can be used.
  • the particulate matter combustion catalyst forms a PM combustion catalyst layer 5 on the inlet 7 side of the filter base 4 across the cell wall 2, and the NOx reduction catalyst on the outlet 10 side across the cell wall 2.
  • the NOx reduction catalyst layer 6 is formed. Either or both of the particulate matter combustion catalyst and the reduction catalyst may be present in the cell wall 2, but the abundance ratio in the cell wall 2 is 50% or less in order to reduce pressure loss desirable.
  • the PM combustion catalyst layer 5 is thicker as going from the inlet 7 of the filter substrate 4 to the depth, and the NOx reduction catalyst layer 6 is formed thicker as it goes from the depth of the filter substrate 4 to the outlet 10 It is characterized by The thicknesses of the PM combustion catalyst layer 5 and the NOx reduction catalyst layer 6 may be changed linearly, but may be changed stepwise, such as stepwise. Further, since the pressure difference can be provided only by changing either one of the thickness of the PM combustion catalyst layer 5 and the thickness of the NOx reduction catalyst layer 6, it is sufficient to change at least one of the thicknesses.
  • the thickness of the PM combustion catalyst layer 5 is preferably 10 ⁇ m or more and 100 ⁇ m or less.
  • the thickness of the PM combustion catalyst layer 5 is preferably 10 ⁇ m or more and 100 ⁇ m or less.
  • the Cs-V complex oxide is characterized in that the interaction with ammonia acting as a reducing agent in the NOx reduction reaction is weak. Therefore, in the temperature range where the exhaust gas temperature is relatively low, the ammonia can be supplied to the NOx reduction catalyst layer 6 located downstream of the exhaust gas flow without being oxidized, and the NOx reduction performance can be exhibited.
  • zeolite containing a base metal component selected from one or more of V 2 O 5 -TiO 2 -WO 3 , TiO 2 -WO 3 , copper and iron components can be used.
  • zeolite containing a copper component is preferable from the viewpoint of NOx reduction performance and heat resistance.
  • the Cs-V complex oxide has a weak interaction with ammonia acting as a reducing agent in the NOx reduction reaction, the reducing agent such as ammonia is added from the upstream side of the exhaust gas purification filter 1 in a relatively low temperature range. Even when supplied, the Cs-V complex oxide can be circulated to the downstream side of the filter substrate 4 without oxidizing the reducing agent.
  • the catalyst of the Cs-V complex oxide contained in the PM combustion catalyst layer 5 has oxygen of the collected PM in the gas phase in a temperature range lower than that of a catalyst using a platinum group metal. It can be made to react quickly and burn off.
  • high PM combustion performance can be exhibited in the cell 3 on the exhaust gas inflow side, and NOx reduction performance can be exhibited also on the cell 3 on the exhaust gas outflow side.
  • the PM combustion catalyst layer 5 is made thicker as going from the inlet 7 of the filter base 4 to the inner side, or from the back of the filter base 4 to the outlet 10.
  • the NOx reduction catalyst layer 6 thicker as it goes, it is possible to make a difference in pressure loss. Since the air passes preferentially through the low pressure drop, the exhaust gas will flow preferentially in the vicinity of the inlet 7 of the filter substrate 4.
  • NOx reduction catalyst NOx reduction catalyst
  • the creepage distance in which the exhaust gas flows through the NOx reduction catalyst layer 6 can be lengthened, and the PM combustion catalyst layer 5 and the NOx reduction catalyst layer As compared with the case where the thickness of 6 is made uniform, NOx can be purified with high efficiency.
  • the exhaust gas purification filter 1 in the exhaust gas purification filter 1, can exhibit high particulate matter combustion performance in the cell 3 on the exhaust gas inflow side, and can exhibit NOx reduction performance in the cell 3 on the exhaust gas outflow side. Can be provided.
  • the exhaust gas purification filter 1 reduces the NOx by the porous filter base 4 having the plurality of cells 3 partitioned by the cell walls 2, the PM combustion catalyst that burns and cleans the PM, and And a NOx reduction and removal catalyst for purification.
  • the PM combustion catalyst is included in part or all of the surface of the cell wall 2 on the side where the exhaust gas flows, and forms a PM combustion catalyst layer 5.
  • the NOx reduction and removal catalyst is included in part or all of the surface of the cell wall 2 on the side where the exhaust gas flows out, and forms the NOx reduction catalyst layer 6.
  • the PM combustion catalyst is a molten salt type catalyst containing a composite oxide of cesium and vanadium, wherein the molar ratio of cesium to vanadium (Cs / V) is 0.5 ⁇ Cs / V ⁇ 1.5. There is.
  • the molten salt type catalyst containing a composite oxide of cesium and vanadium is a direct oxidation type catalyst that burns PM using oxygen in the gas phase.
  • the molten salt catalyst melts in the vicinity of the reaction temperature with PM and becomes a liquid phase. Therefore, in the combustion of PM involving catalyst (solid) -PM (solid) -oxygen (gas), when the catalyst becomes a liquid phase, the contact with PM increases dramatically, and high PM combustion performance is expressed. Conceivable.
  • the composite oxide of cesium and vanadium is characterized in that the interaction with ammonia acting as a reducing agent in the NOx reduction reaction is weak. Therefore, in the temperature range where exhaust gas temperature is relatively low, ammonia can be supplied to the NOx reduction catalyst layer 6 located downstream of the exhaust gas flow without oxidizing ammonia, so the exhaust gas purification filter 1 has NOx reduction performance. Can be demonstrated.
  • an exhaust gas purification filter having high PM combustion performance and NOx reduction performance can be provided.
  • the exhaust gas purification filter 1 is a wall flow type filter base 4 having a plurality of cells partitioned by porous cell walls 2 and particles supported on the filter base 4 to burn and purify particulate matter.
  • a NOx reduction catalyst for purifying NOx is provided.
  • the particulate matter combustion catalyst forms a first catalyst layer on the inlet 7 side of the filter substrate 4 with the cell wall 2 interposed therebetween, and the NOx reduction catalyst forms a second catalyst layer on the outlet 10 side with the cell wall 2 interposed therebetween.
  • the first catalyst layer is formed thicker as it goes from the inlet 7 of the filter substrate 4 to the back, or the second catalyst layer is formed thicker as it goes from the back of the filter substrate 4 to the outlet 10 It is good to be doing.
  • the particulate matter combustion catalyst is a cesium-vanadium composite oxide in which the molar ratio of cesium to vanadium (Cs / V) is 0.5 ⁇ Cs / V ⁇ 1.5, It may be a molten salt type catalyst containing a cerium-containing oxide.
  • the particulate matter combustion catalyst comprising a catalyst comprising a composite oxide of vanadium and cesium, does not require the NO 2 in the combustion of the soot, the exhaust gas particulate containing NO 2 Even if some of the cell wall 2 carrying the material combustion catalyst may permeate, the particulate matter combustion catalyst staying in the cell 3 on the inflow side has a large particle size compared to NO 2 It can be burned.
  • the fact that the exhaust gas containing NO 2 permeates through a part of the cell wall 2 supporting the particulate matter combustion catalyst means that the exhaust gas flows on the surface of the NOx reduction catalyst at the outlet 10 side of the filter substrate 4 The distance can be increased, and efficient NOx purification can be performed.
  • the thickness of the first catalyst layer may be 10 ⁇ m or more and 100 ⁇ m or less.
  • the particulate matter combustion catalyst may be supported on an oxide carrier.
  • fine unevenness of the carrier suppresses unintended movement of the molten salt catalyst in the liquid phase.
  • the specific surface area of the molten salt catalyst can be increased, and the contact with combustion and combustion can be promoted.
  • the exhaust gas purification filter according to the present invention has both high PM combustion performance and NOx reduction performance, the exhaust gas purification filter for purifying the exhaust gas generated from various internal combustion engines and the catalyst DPF for purifying the exhaust gas of a diesel engine It is useful as etc.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Environmental & Geological Engineering (AREA)
  • Combustion & Propulsion (AREA)
  • Health & Medical Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Biomedical Technology (AREA)
  • Mechanical Engineering (AREA)
  • Analytical Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Organic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Exhaust Gas Treatment By Means Of Catalyst (AREA)
  • Processes For Solid Components From Exhaust (AREA)
  • Catalysts (AREA)

Abstract

Un filtre de purification de gaz d'échappement comprend un matériau de base de filtre poreux possédant une pluralité de cellules délimitées par des parois cellulaires, une couche de catalyseur de combustion de matières particulaires comprenant un catalyseur de combustion de matières particulaires qui brûle et purifie les matières particulaires, et une couche de catalyseur de réduction de NOx comprenant un catalyseur de réduction/élimination de NOx qui réduit et purifie les NOx. La couche de catalyseur de combustion de matières particulaires comprend une partie ou la totalité de la surface des parois cellulaires sur le côté d'entrée des gaz d'échappement. La couche de catalyseur de réduction de NOx comprend une partie ou la totalité de la surface des parois de cellule sur le côté de sortie des gaz d'échappement. Le catalyseur de combustion de matières particulaires est constitué d'un catalyseur de sel fondu qui comprend un oxyde composite de césium et de vanadium et dans lequel le rapport molaire (Cs/V) de césium au vanadium est de 0,5 ≤ Cs/V ≤ 1,5, ce par quoi on obtient un filtre de purification de gaz d'échappement possédant à la fois une performance de combustion de matières particulaires élevée et une performance de réduction de NOx élevée.
PCT/JP2018/033529 2017-09-21 2018-09-11 Filtre de purification de gaz d'échappement WO2019059032A1 (fr)

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Cited By (1)

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US11976236B2 (en) 2022-01-26 2024-05-07 Halliburton Energy Services, Inc. Methods and compositions for enhancing integrity and thermal conductivity of wellbores in geothermal operations

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Publication number Priority date Publication date Assignee Title
US11976236B2 (en) 2022-01-26 2024-05-07 Halliburton Energy Services, Inc. Methods and compositions for enhancing integrity and thermal conductivity of wellbores in geothermal operations

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