Classifications

• • 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
  • F01N3/2828—Ceramic multi-channel monoliths, e.g. honeycombs
• • 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
  • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J19/24—Stationary reactors without moving elements inside
  • B01J19/248—Reactors comprising multiple separated flow channels
  • B01J19/2485—Monolithic reactors
• • 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
  • F01N3/2807—Metal other than sintered metal
  • F01N3/281—Metallic honeycomb monoliths made of stacked or rolled sheets, foils or plates
  • F01N3/2821—Metallic honeycomb monoliths made of stacked or rolled sheets, foils or plates the support being provided with means to enhance the mixing process inside the converter, e.g. sheets, plates or foils with protrusions or projections to create turbulence
• • 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
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/32—Details relating to packing elements in the form of grids or built-up elements for forming a unit of module inside the apparatus for mass or heat transfer
  • B01J2219/322—Basic shape of the elements
  • B01J2219/32296—Honeycombs
• • 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
  • F01N2330/00—Structure of catalyst support or particle filter
  • F01N2330/02—Metallic plates or honeycombs, e.g. superposed or rolled-up corrugated or otherwise deformed sheet metal
• • 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
  • F01N2330/00—Structure of catalyst support or particle filter
  • F01N2330/06—Ceramic, e.g. 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
  • F01N2330/00—Structure of catalyst support or particle filter
  • F01N2330/30—Honeycomb supports characterised by their structural details
  • F01N2330/38—Honeycomb supports characterised by their structural details flow channels with means to enhance flow mixing,(e.g. protrusions or projections)

Definitions

• the present invention relates to a catalyst support of the monolith type with networks of intersecting channels as well as to a catalyst comprising such a support and to the process making it possible to obtain such a catalyst support.
• It relates more particularly to supports used in catalytic reactions and ensuring, by their structural characteristics, specific regimes for the hydrodynamics of the flows of fluids beneficial to the catalytic activity of the transformation of gaseous and / or liquid reactants which cross them.
• the catalytic phases implemented are generally deposited on monolithic supports made of ceramic materials or metal.
• These supports are generally produced by extruding ceramic or by rolling up corrugated metal strips or by superimposing metal sheets so as to obtain a monolithic body with a single network of one-dimensional and one-way channels.
• the fluid to be treated will thus pass through the channels present in this support and the constituents of this fluid will react on contact with the catalytic phases present in these channels.
• reaction performance of the catalysts prepared on such supports is not always sufficient since the contact time of the reactants with the catalytic phase is not sufficient to obtain, at the end of the treatment, a "clean" fluid.
• the present invention proposes to remedy the above-mentioned drawbacks by having a catalyst support which allows, by virtue of these particular effects on the hydrodynamics of the flow of the fluid, to impart to the catalytic reaction in which it participates. , additional activity for the transformation of reagents.
• a catalyst support comprising a monolithic body with an initial network of channels is characterized in that it comprises at least one additional network of channels with an arrangement according to which the channels of the networks are intersecting between them.
• the section of the channels of the initial network is different from that of the channels of the additional network.
• the density of the channels of the initial network is different from that of the channels of the additional network.
• the directional axes of at least two networks of intersecting channels form an angle between them of between 10 and 170 degrees.
• the ratio between the open sections of the channels belonging respectively to at least two intersecting networks is between 1 and 10,000.
• the ratio between the number of small section channels belonging to a first network and the number of wider section channels belonging to at least one second intersecting network is between 0.001 and 1000.
• the channels of at least one network have a continuous and rectilinear structure.
• the catalyst support comprises a monolithic structure constituted by a ceramic material.
• this catalyst support comprises a monolithic structure constituted by a metallic material.
• the catalyst support comprises a monolithic structure constituted by a composite and / or synthetic material.
• This monolithic structure has a honeycomb, foam or fiber structure.
• a catalyst support is used for a catalyst for the purification of exhaust gases or for a catalyst for catalytic reactions between two fluids.
• a method for producing a catalyst support comprising a monolithic body is characterized in that:
• the constituent material of the monolithic body is impregnated with at least one catalyst; - At least one additional network of channels is formed in the same body in such a way that the channels of the networks are intersecting between them.
• the initial network and at least one additional network of channels are simultaneously formed.
• the constituent material of the monolith body is impregnated with catalyst before the said body is produced.
• FIG. 1 is a perspective view of a catalyst support according to the prior art
• - Figure 2 is a schematic view in partial section along the plane AA of Figure 1;
• FIG. 3 is a schematic view in partial section showing a catalyst support according to the invention.
• the catalyst support of the prior art comprises a monolithic body 1, here by way of example of parallelepipedal shape, comprising a network of channels 2 monodirectional and distributed in a regular and homogeneous manner.
• These channels have the same open cross section S1 and pass right through the monolithic body 1 along a substantially rectilinear path, being from one face of the monolithic body to end on the opposite face of this body.
• This monolith can be produced with different materials such as ceramic, metallic, composite or synthetic material in the form of a “honeycomb” structure, of foam, of woven fibers or of tangled fibers (felt).
• materials such as ceramic, metallic, composite or synthetic material in the form of a “honeycomb” structure, of foam, of woven fibers or of tangled fibers (felt).
• the most common monoliths and certainly the least expensive to manufacture are those made of ceramic, the essential components of which can be alumina, alumino-silicates possibly doped with zirconia (cordierite, mullite, mullite-zirconia, ...) .
• Materials which are more difficult to process and cost more are silicon carbides and nitrides.
• Ceramic monoliths can have a “honeycomb” structure, that is to say that they comprise a homogeneous network of rectilinear unidirectional channels. These monoliths, produced by an extrusion technique, and generally used as a catalyst support for the depollution of automobile exhaust gases, can be crossed by ten to one hundred channels per square centimeter (100 to 600 cpsi) of more or less wide section (of the order of 0.5 to 1.5 mm side if the channels are square). For applications in depollution of thermal power plant discharges, this same monolith structure is implemented with generally different materials, wider channel sections (of the order of cm 2 ) and a more restricted channel density.
• Foams made with this same type of ceramic material, or with nitrides or silicon carbides can also be used as well as foams made of synthetic or composite materials.
• fibrillar structures of these materials in the form of entangled fibers (felt type) or of woven fibers can also be chosen, in order to obtain, after shaping, monolithic supports.
• the initial network of channels will be constituted by the pores of the foam or the cells of the fibrillar structure and the channels will no longer be unidirectional or continuous and their size will generally be more restricted.
• Metal supports can also be used and industrial monoliths having a network of channels are used, in particular for catalytic support applications for the purification of automobile exhaust gases.
• the materials generally used are special steels of the “Fecralloy” type, or aluminized or aluminized steels. These steels contain, either in their composition or on the surface of the material, aluminum which, after special treatment, reveals on the surface a micro-layer of alumina which protects the support, under severe conditions of use (temperature, environment oxidizing and corrosive), mechanical, structural or physico-chemical deterioration, too rapid.
• These materials used in the form of strips (sheets a few tens of microns thick) or in the form of fibers can lead to the production of monoliths having, during their design, a network of channels.
• the previously corrugated strips can be rolled to produce monoliths with a honeycomb structure.
• corrugated strips after cutting, can also be stacked to produce monoliths where the channels of the same network communicate with each other. Fibers a few centimeters in length and a few tens of millimeters in width can also be produced from these materials. By compression and welding of these fibers together, monoliths can be produced.
• wash-coat a coating of large specific surface (approximately 50 to 200 m 2 / g), generally called wash-coat.
• This deposition is carried out in one or more stages so that the support is uniformly covered by this coating.
• One technique consists of immersing the support in a suspension of the product to be used, then blowing off the excess material which clogs the channels, and finally fixing this coating on the support material by one or more drying operations. -calcination.
• the active elements of the catalyst are generally transition metals (Cu, Co, Ni, Fe, Mo, Mn, ...) or precious or noble metals (Pt, Pd, Rh, Ru, Ir, Au, Ag ,. ..). They are usually introduced in the form of a solution of their soluble salts (nitrates, chlorides, acetates, ). This operation can be done after the coating step according to techniques known to those skilled in the art, such as dry or excess impregnation, by spraying of solution onto and into the coated monolith, or by exchange ionic. These active elements can also be deposited on the materials constituting the coating (wash-coat) before the coating step.
• This support is coated in its entirety, including in channels 2, with a coating (wash-coat) of alumina at the rate of 100 g per liter of substrate;
• This catalyst support is loaded into a catalytic reactor, ensuring that the system is perfectly sealed;
• the temperature rise of the reactor is programmed to the regulator at a rate of 5 ° C / min;
• An analyzer equipped with a flame ionization detector is placed at the outlet of the reactor and makes it possible to continuously monitor the evolution of the hydrocarbon concentration (analysis of total carbon in methane equivalent) after catalytic reaction and thus determine the rate of conversion of xylenes.
• FIG. 3 shows a catalyst support according to the invention.
• This support comprises a monolithic body 1 with a network of channels 2, called in the following description the initial network of channels, which has the same characteristics as those described in relation to FIGS. 1 and 2.
• the body 1 comprises at least one additional network of channels 3 whose channels are intersecting with the channels of the initial network and preferably, intersecting at least two by two.
• the channels 3 have an open cross section S2 as well as a density different from that of the channels of the initial network.
• the ratio between the number of small section channels belonging to a network and the number of wider section channels belonging to at least one intersecting network is between 0.001 and 1000.
• channels 3 of at least one additional network can have a non-homogeneous distribution and distribution as well as a non-rectilinear direction.
• the ratio of the open sections of the channels of larger section to those of the channels of smaller section is between 1 and 10000, preferably between 1 and 5000 and preferably between 1 and 1000 and the ratio between the number of channels 2 belonging to the initial network and the number of channels 3 belonging to an additional network, intersecting with the initial network, is between 1 and 1000, preferably between 1 and 500 and preferably between 1 and 100.
• Each of the networks of channels has a different orientation in space and the directional axes of each of these networks, intersecting them at least two by two, are oriented in such a way that the angles defined between each of them are between 10 and 170 degrees, preferably between 30 and 150 degrees and preferably between 60 and 120 degrees.
• this additional network will have a lower density of channels whose opening sections will be wider.
• the additional network may be designed with channels of smaller open section.
• the number of channels of smaller section will be greater than that of channels of upper section.
• the channels belonging to the initial network of intersecting channels are distributed in a regular and homogeneous manner on one face of the monolithic support and have the same open section and pass right through the monolith along a preferably rectilinear path.
• the geometric distributions of the opening of the channels belonging to them as well as the homogeneity of their distribution over a section of the support and their straight profile. may be imperfect.
• This additional network can be easily produced, either before or after the deposition of the catalytic phase, by usual drilling techniques (mechanical, electromechanical, laser), but other techniques can also be developed to create during the shaping of the monolith, two or more networks of channels meeting the specifications of the invention.
• a catalyst support consisting of fibers
• provision may be made to coat the fibers with the catalytic phase and then to form the monolithic body with its networks of channels.
• a monolith of the prior art is modified by creation of an additional network of channels 3 arranged substantially perpendicular to the initial network of channels 2 and composed by 85 4 mm diameter channels with a density of 0.85 channels per cm 2 (6 cpsi) and a section open S2 of approximately 12 mm 2 , distributed uniformly over the entire section of the monolith.
• the catalyst support is loaded into the reactor while respecting the same direction of passage of the gases through the monolith, namely through the initial network of channels 2.
• the same operating conditions for the conduct of the experiment are applied.
• the above catalyst support is recharged in the reactor, as shown in FIG. 4, in such a way that the gases circulate through the additional network of channels 3 which is less dense but whose open section of each channel is about twelve times larger.
• TLO half-conversion temperature
• the difference in efficiency between the catalyst of FIG. 2 and that of FIG. 4 can be analyzed by the modification of the hydrodynamic flows between the channels 2 and 3. For example, if the circulation of the gases is in turbulent state in the channels 3 of FIG. 4, the circulation in the channels 2 of the catalyst of FIG. 2 can be in laminar state
• the channels 3, of open section of 12 mm 2 are provided on their periphery with cavities resulting from the initial secant network of channels 2, which causes a roughness of the walls of the channels 3 which can, in certain conditions, generating a circulation of gases in channels 3 in a turbulent state with a Reynolds Number less than 2100, taking into account said conditions.
• the Applicant has used two commercially available Diesel oxidation catalysts, prepared on ceramic supports with a honeycomb structure. impregnated with catalysts with a density of 48 channels per cm 2 (300 cpsi) and an open section of approximately 1 mm 2 , cut in the form of a 10 ⁇ 10 ⁇ 10 cm cubic support (total volume of 2 I).
• CO by IR
• HC by FID
• This catalyst has the particularity of trapping nitrogen oxides (NOx) when the engine operates in a lean mixture and the nitrogen oxides thus adsorbed are then reduced to molecular nitrogen during intermittent fuel injections.
• NOx nitrogen oxides
• the catalytic phase used is composed of precious metals and is deposited on an alumina doped with barium (about 15% by weight) which serves both as a support for the precious metals and as an adsorbent mass for the oxides of nitrogen.
• the first test is carried out using two ceramic monoliths with a honeycomb structure having the dimensions of those described above in relation to the commercial diesel oxidation catalysts and on which the adsorbent catalytic phase is deposited at the right rate.
• the set of two monoliths arranged in series is installed on an exhaust line of a diesel engine for which the operating conditions are adjusted so that the temperature of the exhaust gases passing through the catalyst is 300 °. C and their space velocity (VVH) is 50000h "1 . Under these test conditions, it has been found that the quantity of nitrogen oxides trapped on the adsorbent mass corresponds to 9% of the mass theoretically adsorbable on the support before emissions of oxides of nitrogen at the outlet of the adsorbent catalytic mass.
• This additional network of channels is substantially perpendicular to the initial network and comprises approximately 1.5 channels per cm 2 with an open section of 7 mm 2 .
• the amount of nitrogen oxides trapped is increased by more than 60%.
• a final series of tests is conducted with a 3-way type catalyst mounted on the exhaust line of a vehicle equipped with a petrol engine whose richness is regulated to the stoichiometric value (richness
• NMVEG European standardized pollution test
• the parameter followed was the time necessary for the ignition of the catalyst, that is to say the time which elapses between the starting of the engine (with a temperature of the catalyst for which the rate of conversion of pollutants is zero) and the start of catalytic activity (with a temperature known as TLO "Light Off Temperature" for which more than 50% of pollutants are converted).
• the same quantity of catalytic phase was deposited either on ceramic supports of the prior art with an initial network of channels of 66 channels per cm 2 , or on supports according to the invention which comprises, in plus, an additional network of channels arranged substantially perpendicular to the initial network and which comprises approximately 1.4 channels per cm 2 with an open section of 7 mm 2 .
• the two supports were tested under the same conditions and it was found that the time to reach the so-called TLO temperature was 165 seconds for the support of the prior art and 115 seconds for the support according to the invention.
• the present invention is not limited to the examples described in relation to catalytic reactions for a fluid resulting from combustion in an internal combustion engine, such as exhaust gases, but encompasses all variants. It can in particular be applied to catalysts for catalytic reactions allowing the catalysis of a fluid under a gaseous or liquid phase as generally used in the field of petroleum treatment.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Mechanical Engineering (AREA)
• Toxicology (AREA)
• Combustion & Propulsion (AREA)
• Health & Medical Sciences (AREA)
• General Engineering & Computer Science (AREA)
• Ceramic Engineering (AREA)
• Organic Chemistry (AREA)
• Catalysts (AREA)
• Physical Or Chemical Processes And Apparatus (AREA)
• Exhaust Gas After Treatment (AREA)
• Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

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• 2001
  • 2001-04-05 FR FR0104760A patent/FR2823139B1/fr not_active Expired - Fee Related
• 2002
  • 2002-04-05 AT AT02730353T patent/ATE400363T1/de not_active IP Right Cessation
  • 2002-04-05 EP EP02730353A patent/EP1381464B1/fr not_active Expired - Lifetime
  • 2002-04-05 US US10/474,054 patent/US7141530B2/en not_active Expired - Fee Related
  • 2002-04-05 DE DE60227499T patent/DE60227499D1/de not_active Expired - Lifetime
  • 2002-04-05 JP JP2002579116A patent/JP2004533314A/ja not_active Ceased
  • 2002-04-05 WO PCT/FR2002/001191 patent/WO2002081083A1/fr not_active Ceased

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