EP1957184A1 - Diffuseur pour systemes d'épuration de gaz d'échappement - Google Patents

Diffuseur pour systemes d'épuration de gaz d'échappement

Info

Publication number
EP1957184A1
EP1957184A1 EP06817731A EP06817731A EP1957184A1 EP 1957184 A1 EP1957184 A1 EP 1957184A1 EP 06817731 A EP06817731 A EP 06817731A EP 06817731 A EP06817731 A EP 06817731A EP 1957184 A1 EP1957184 A1 EP 1957184A1
Authority
EP
European Patent Office
Prior art keywords
diffuser
exhaust gas
flow
gas purification
ceramic
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
EP06817731A
Other languages
German (de)
English (en)
Inventor
Christian Bach
Konstantinos Boulouchos
Panayotis Dimopoulos
Ulrich Vogt
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Eidgenoessische Technische Hochschule Zurich ETHZ
Eidgenoessische Materialprufungs und Forschungsanstalt EMPA
EMPA
Original Assignee
Eidgenoessische Technische Hochschule Zurich ETHZ
Eidgenoessische Materialprufungs und Forschungsanstalt EMPA
EMPA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Eidgenoessische Technische Hochschule Zurich ETHZ, Eidgenoessische Materialprufungs und Forschungsanstalt EMPA, EMPA filed Critical Eidgenoessische Technische Hochschule Zurich ETHZ
Publication of EP1957184A1 publication Critical patent/EP1957184A1/fr
Ceased legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
    • B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
    • B01D53/9445—Simultaneously removing carbon monoxide, hydrocarbons or nitrogen oxides making use of three-way catalysts [TWC] or four-way-catalysts [FWC]
    • B01D53/945—Simultaneously removing carbon monoxide, hydrocarbons or nitrogen oxides making use of three-way catalysts [TWC] or four-way-catalysts [FWC] characterised by a specific catalyst
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
    • B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
    • B01D53/9445—Simultaneously removing carbon monoxide, hydrocarbons or nitrogen oxides making use of three-way catalysts [TWC] or four-way-catalysts [FWC]
    • B01D53/9454—Simultaneously removing carbon monoxide, hydrocarbons or nitrogen oxides making use of three-way catalysts [TWC] or four-way-catalysts [FWC] characterised by a specific device
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/50—Catalysts, in general, characterised by their form or physical properties characterised by their shape or configuration
    • B01J35/56—Foraminous structures having flow-through passages or channels, e.g. grids or three-dimensional monoliths
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/0215—Coating
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B38/00—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof
    • C04B38/06—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof by burning-out added substances by burning natural expanding materials or by sublimating or melting out added substances
    • C04B38/0615—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof by burning-out added substances by burning natural expanding materials or by sublimating or melting out added substances the burned-out substance being a monolitic element having approximately the same dimensions as the final article, e.g. a porous polyurethane sheet or a prepreg obtained by bonding together resin particles
    • 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
    • F01N3/24—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 characterised by constructional aspects of converting apparatus
    • F01N3/28—Construction of catalytic reactors
    • F01N3/2803—Construction of catalytic reactors characterised by structure, by material or by manufacturing of catalyst support
    • F01N3/2825—Ceramics
    • 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
    • F01N3/24—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 characterised by constructional aspects of converting apparatus
    • F01N3/28—Construction of catalytic reactors
    • F01N3/2892—Exhaust flow directors or the like, e.g. upstream of catalytic device
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15D—FLUID DYNAMICS, i.e. METHODS OR MEANS FOR INFLUENCING THE FLOW OF GASES OR LIQUIDS
    • F15D1/00—Influencing flow of fluids
    • F15D1/001—Flow of fluid from conduits such as pipes, sleeves, tubes, with equal distribution of fluid flow over the evacuation surface
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/40—Mixed oxides
    • B01D2255/402—Perovskites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/90—Physical characteristics of catalysts
    • B01D2255/908—O2-storage component incorporated in the catalyst
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/90—Physical characteristics of catalysts
    • B01D2255/92—Dimensions
    • B01D2255/9207—Specific surface
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
    • C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
    • C04B2111/00793—Uses not provided for elsewhere in C04B2111/00 as filters or diaphragms
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
    • C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
    • C04B2111/0081—Uses not provided for elsewhere in C04B2111/00 as catalysts or catalyst carriers
    • 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
    • F01N2240/00—Combination or association of two or more different exhaust treating devices, or of at least one such device with an auxiliary device, not covered by indexing codes F01N2230/00 or F01N2250/00, one of the devices being
    • F01N2240/20—Combination or association of two or more different exhaust treating devices, or of at least one such device with an auxiliary device, not covered by indexing codes F01N2230/00 or F01N2250/00, one of the devices being a flow director or deflector
    • 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
    • Y02T10/12—Improving ICE efficiencies

Definitions

  • the invention relates to a diffuser with or without catalytic activity, which is suitable for use in exhaust gas purification systems of engines, with diesel engines, gasoline and gas engines in vehicles as well as stationary engines.
  • a large active surface This consists of a ceramic or metallic carrier body, which can be coated with aluminum oxide, for example, to enlarge the surface.
  • this surface can be coated with precious metals such as platinum, palladium or rhodium or perovskites.
  • Such catalytic effects serve the purpose of generating harmless nitrogen (N 2 ) or reactive nitrogen dioxide (NO 2 ) from the nitrogen oxides (NO x ), converting carbon monoxide (CO) into carbon dioxide (CO 2 ) and from unburned or partially burned hydrocarbons ( HC) to produce carbon dioxide (CO 2 ) and water (H 2 O).
  • Liquid or solid reactants for example ammonia solutions, urea solutions or fuel, are sometimes added to the exhaust gas in order to produce chemical reactions in the catalysts or to increase the temperatures.
  • the invention has for its object to provide a diffuser as the active surface, by means of which on this first treatment unit, the exhaust gas stream, optionally including metered reactants is fanned out as homogeneously as possible.
  • downstream exhaust gas treatment systems such as particle filters or catalysts are subjected to a homogeneous flow across the entire cross-section and in the composition of the exhaust gas, and secondly - in the case of a catalytically coated diffuser - the catalytically active surface in the diffuser itself is used as much as possible.
  • the diffuser should be designed so that it generates as little flow resistance as possible. Furthermore, this diffuser should take into account the fact that the entire exhaust gas aftertreatment unit can be made compact, both with regard to limited space and with regard to cheap manufacture and handling in series production.
  • the incoming exhaust gas flows into an extruded ceramic body which, for example, has a honeycomb or grid-like cross section, the individual honeycombs forming very thin cannulas running parallel to one another, through which the gas is passed.
  • the cannula walls are coated, for example, with aluminum oxide and noble metals or perovskites.
  • the exhaust gas comes into contact with the cannula walls as it flows through, which, due to their specific coating, leads to catalytic reactions.
  • the overall cross section of this ceramic body must be dimensioned significantly larger than that of the exhaust pipe.
  • the exhaust gas flow must first be fanned out from the diameter of the exhaust pipe and only then can the full cross-section flow in and through the ceramic body.
  • the central area of the ceramic body and the cannulas located there Because of the speed distribution of the gas flow over the exhaust pipe cross-section, the flow flows more strongly than the edge regions of the ceramic body. In some cases, the fanning out is off-center, so that the area with more flow is also off-center. In such cases, the flow away from the peripheral areas is even weaker.
  • the particle filter adjoining the catalytic ceramic body shows a similar structure consisting of fine cannulas arranged parallel to one another, the one being closed at the front like a chessboard and the adjacent one at the rear.
  • the gas flows into the cannulas, which are open at the front, and must then forcibly diffuse through the porous cannula walls into the neighboring cannulas, from which it emerges on the rear side of the particle filter and into an exhaust tailpipe.
  • the solids in the form of soot particles collected in the particle filter are burned off periodically or continuously, which regenerates the filter. Similar flow situations prevail in catalysts, for example in oxidation, 3-way or DeNOx catalysts, but without mutually closed cannulas.
  • gaseous, liquid or solid reactants metered into the exhaust gas for example ammonia or urea solutions or fuel
  • gaseous, liquid or solid reactants metered into the exhaust gas cannot mix homogeneously in the exhaust gas stream, for example in the case of short mixing distances or due to inertial forces, which leads to locally different concentrations of the reactant and thus to non-optimal ones Systems leads.
  • the present invention thus wants to create a flow body which homogenizes an inhomogeneous speed distribution and inhomogeneous composition of the exhaust gas stream, and which can also be carried out catalytically effective in a special embodiment.
  • the gas flow and the composition of the metered reactants should thus be distributed more homogeneously over the flow cross section. This is to ensure that downstream particle filters or catalysts are flowed towards as far as possible by a gas stream with a homogeneous velocity distribution and a homogeneous composition.
  • This flow body should be inexpensive to manufacture and have the largest possible active area for the gas flowing through.
  • a diffuser for exhaust gas purification systems consisting of a foam or sponge-like or three-dimensional lattice-like, macroscopically flowable ceramic structure in all directions.
  • the diffuser can be catalytically coated and is then catalytically active or else it is not catalytically active if it is not particularly coated.
  • Figure 1 is a schematic representation of a conventional structure of a
  • Exhaust gas purification system with a catalytic flow body with a honeycomb cross section and a downstream particle filter;
  • Figure 2 is a schematic representation of the structure of an exhaust gas purification system with a diffuser of the present invention in the form of a flow body made of a ceramicized polyurethane foam and a downstream particle filter.
  • Another aspect is the mixing and swirling of the gases, especially at right angles to the flow axis, which should be caused by the flow. rather structures arise.
  • This result is important for the intimate mixing of pollutants in the exhaust gas before it reaches catalytic converters and collectors or particle filters, where the particles are retained and / or chemical reactions take place. Only with well-mixed exhaust gases can it be ensured that the catalyst and collector surfaces are evenly loaded. It has been shown that these ceramic structures, which are porous in all directions, generate strong turbulence in the gases after they have emerged from the structures. This leads to the conclusion that the turbulence is even more pronounced inside the structures. The turbulence is strongest directly at the exit from the structure and then, as expected, weakens continuously in the free flow channel.
  • the strong turbulence inside the structure is very conducive to efficient interaction with the catalytic surface of the structure. Accordingly, the rate of the converted pollutants when flowing through such a catalytic structural body is significantly increased compared to the flow through a channel catalyst. This is particularly important when you consider that the flow through a regular monolithic body like the previous ceramic flow bodies is largely laminar, with a low Reynolds number. With this dimensionless number, the kinetic energy density is compared with the friction loss density.
  • the velocity gradient transverse to the direction of flow is estimated by the typical value of the velocity and the characteristic length or dimension of the system, for example the diameter of a flow tube.
  • the Reynolds number is therefore a stability criterion for laminar flows.
  • the gas flow in a ceramic, foam or sponge-like flow body that is porous in all directions is considerably more turbulent than that in a monolithic flow body with straight flow channels,
  • a catalytically active that is, a catalytically coated or even just a catalytically inactive, that is, a catalytically uncoated diffuser for exhaust gas purification systems, which consists of such a foam or sponge-like porous ceramic structure
  • a catalytically uncoated diffuser for exhaust gas purification systems which consists of such a foam or sponge-like porous ceramic structure
  • open-cell foam or sponge ceramics are produced, for example, by the Schwartzwalder process, described in US Pat. No. 3O90O94 the year 1963.
  • recirculated polymer foams are impregnated with a ceramic suspension and pressed out using squeeze rollers or similar methods, and the molded parts are then dried.
  • the pore size of the foam ceramic is determined by the polymer foam and is, for example, between 5 and 50 ppi, which corresponds to approximately 5000 to 500 ⁇ m.
  • the subsequent temperature treatment of the polymer foam is thermally degraded at a temperature of for example 300-600 0 C.
  • the sintering temperature depending on the material being between 1000-2200 0 C.
  • One or more post-infiltrations and by coating the porous ceramic body can significantly increase its strength. It is also possible to infiltrate or coat the ceramic foam with a catalytically active material and to subject this layer to a temperature treatment. In professional circles, one speaks regularly of ceramic foams, although these are permeable on all sides and therefore resemble a sponge structure rather than a foam structure.
  • FIG. 1 shows a schematic representation of a catalyst 1 with a particle filter 2, installed in an exhaust pipe 3 of an internal combustion engine. It is housed in a muffler 4, which has a larger diameter than the supplying exhaust pipe 3. In the first area of the muffler 4, the catalytic converter 1 is arranged, to which the particle filter 2 connects.
  • the task of the catalytic converter 1 is to convert the incoming pollutants permanently in the smallest possible space with the lowest possible pressure drop. The pollutants react chemically on the catalyst surface.
  • an extruded ceramic body has been used for this purpose, which has been coated with a catalytically active noble metal in a single- or multi-layer process to enlarge its surface, for example with aluminum oxide.
  • Such an extruded catalyst body consists of a very large number of parallel, adjacent and straight flow channels 5.
  • the inner wall of each flow channel 5 forms the surface with which the pollutant molecules flowing through have a catalytic effect can. Gas which has once flowed into the catalyst body is trapped in the fine flow channels 5 and can only flow along these channels 5. Cross flows are not possible.
  • a speed distribution in front of the catalyst 1 has a corresponding effect.
  • a typical distribution curve is drawn qualitatively in the exhaust pipe 1 with a few speed vectors.
  • the direct flow area of the catalyst 1 is therefore always acted upon by gas molecules at a much greater speed than the outer areas.
  • the edges of the catalyst body are flowed through much weaker.
  • a typical distribution curve of the axial velocities is plotted qualitatively above the catalytic converter 1, the velocities being plotted as vectors. Therefore, the different surfaces of this catalyst 1 are inevitably exposed to gas molecules in very different ways: where the flow rates are high, more gas molecules pass by each time and can react catalytically with the catalyst surface there.
  • the catalytic effect will therefore decrease more rapidly in the central area due to aging than in the peripheral areas, and if the catalyst 1 is deemed to be used, the peripheral areas are still intact.
  • the gases experience only slight turbulence inside the catalytic converter 1, so the superimposed axial speed is changed only slightly.
  • Behind the catalytic converter 1, too a distribution curve of the speeds is measured at speeds much higher in the center than towards the edge of the muffler 4.
  • This markedly inhomogeneous speed distribution which is also shown qualitatively, has a disadvantageous effect on the operation of downstream exhaust gas aftertreatment systems, such as, for example, particle filters or other catalysts 2.
  • These treatment systems generally consist of a multiplicity of porous flow channels 6, 7 lying next to one another, with the particle filter 2 alternately half 6 of these channels 6, 7 being closed at the rear in a checkerboard manner and the other half 7 at the front of the particle filter 2 being closed in a checkerboard manner.
  • all of the flow channels 6 that are exposed to flow and open at the front act like pockets.
  • the gases must diffuse through the porous walls of these pockets into the adjacent flow channels 7, so that the gases then inevitably emerge from the rear emerge from the open ends of these flow channels 7 and are expelled through the exhaust pipe into the open. If, for example, the gases hit the inlet cross-section of the particle filter 2 at very different speeds, i.e.
  • This ceramic structure therefore works excellently as a diffuser and releases the flowing gases evenly over the entire muffler cross-section in downstream exhaust gas aftertreatment systems such as catalytic converters, DeNox systems or particle filters 2.
  • exhaust gas aftertreatment systems such as catalytic converters, DeNox systems or particle filters 2.
  • this is, for example, in a dipping process with one or more surface-enlarging, oxygen-storing and / or catalytically active Coated materials.
  • such a foam-like or sponge-like or three-dimensional lattice-like ceramic structure 8 that can be flowed through macroscopically in all directions can be produced, for example, by immersing a polyurethane foam in a ceramic slip. The polyurethane foam coming out of the ceramic slip and soaked with ceramic is then dried and afterwards the polyurethane foam is burned out of the resulting structure. What remains is a three-dimensional foam or sponge-like or lattice to net-like structural body. In the macroscopic sense, a gas can flow through it in every direction. This hard structural body can be coated with catalytically active material at the same time or subsequently in a further process.
  • this coating can contain surface-enlarging and / or oxygen-storing materials as well as noble metals or perovskite materials. Platinum, palladium and rhodium are suitable as precious metals for the treatment of exhaust gases from internal combustion engines.
  • a ceramic body produced and coated in this way can be produced in any geometrical shape by previously producing the polyurethane foam in the desired geometric shape or by cutting it into such a shape that it replaces the previous ceramic body as a diffuser and at the same time as a catalyst in an exhaust pipe or can be installed in the exhaust pipe of an exhaust pipe.
  • catalytically coated or non-coated versions brings about a homogeneous fanning out of the incoming inhomogeneous exhaust gas stream during operation and, in the case of catalytically coated versions, treats the same catalytically particularly uniformly at the same time.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Combustion & Propulsion (AREA)
  • Health & Medical Sciences (AREA)
  • Mechanical Engineering (AREA)
  • Ceramic Engineering (AREA)
  • Organic Chemistry (AREA)
  • Materials Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • General Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Toxicology (AREA)
  • Biomedical Technology (AREA)
  • Fluid Mechanics (AREA)
  • Physics & Mathematics (AREA)
  • Structural Engineering (AREA)
  • Exhaust Gas After Treatment (AREA)
  • Catalysts (AREA)
  • Exhaust Gas Treatment By Means Of Catalyst (AREA)

Abstract

L'invention concerne un diffuseur catalytiquement actif ou non qui convient pour des systèmes d'épuration de gaz d'échappement de moteurs à combustion interne. Il est constitué d'une structure (8) en céramique formée à partir d'une mousse de polyuréthane céramisée. Cette structure (8) en céramique peut être revêtue de matériaux et/ou de métaux précieux qui augmentent sa surface et/ou retiennent l'oxygène pour exercer un effet catalytique sur les molécules de gaz qui le traversent. Comme l'intérieur du diffuseur est poreux dans toutes les directions, un gaz et sa pression peuvent se propager de manière identique de tous les côtés dans la totalité du volume du diffuseur. On obtient une répartition presque homogène des vitesses sur toute la section transversale d'écoulement et on crée une turbulence accrue qui entraîne une multiplication des contacts des molécules nocives avec les parois. En même temps, les systèmes raccordés en aval sont alimentés et traversés sur toute leur section transversale de manière régulière, par un gaz d'échappement mélangé de manière homogène et éventuellement des agents réactifs ajoutés. Globalement, ce diffuseur permet de réaliser de manière plus économique et plus compacte un système d'épuration de gaz d'échappement de même rendement.
EP06817731A 2005-12-05 2006-12-01 Diffuseur pour systemes d'épuration de gaz d'échappement Ceased EP1957184A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH19192005 2005-12-05
PCT/CH2006/000679 WO2007065284A1 (fr) 2005-12-05 2006-12-01 Diffuseur pour systemes d'épuration de gaz d'échappement

Publications (1)

Publication Number Publication Date
EP1957184A1 true EP1957184A1 (fr) 2008-08-20

Family

ID=36588960

Family Applications (1)

Application Number Title Priority Date Filing Date
EP06817731A Ceased EP1957184A1 (fr) 2005-12-05 2006-12-01 Diffuseur pour systemes d'épuration de gaz d'échappement

Country Status (3)

Country Link
US (1) US20090139400A1 (fr)
EP (1) EP1957184A1 (fr)
WO (1) WO2007065284A1 (fr)

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DE202006007876U1 (de) * 2006-05-15 2007-09-20 Bauer Technologies Gmbh Optimierung von zellulären Strukturen, insbesondere für die Abgasreinigung von Verbrennungsaggregaten und andere Anwendungsbereiche
US8377175B2 (en) 2010-02-26 2013-02-19 Arcelormittal Investigacion Y Desarrollo, S.L. Apparatus and method for treating exhaust gas
US20120115709A1 (en) * 2010-11-09 2012-05-10 Sienna Technologies, Inc. High Temperature Catalysts for Decomposition of Liquid Monopropellants and Methods for Producing the Same
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