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
  • B01D53/9481—Catalyst preceded by an adsorption device without catalytic function for temporary storage of contaminants, e.g. during cold start
• • 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
  • B01D53/46—Removing components of defined structure
  • B01D53/54—Nitrogen compounds
  • B01D53/56—Nitrogen oxides
• • 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
  • B01D53/9404—Removing only nitrogen compounds
  • B01D53/9409—Nitrogen oxides
  • B01D53/9413—Processes characterised by a specific catalyst
  • B01D53/9422—Processes characterised by a specific catalyst for removing nitrogen oxides by NOx storage or reduction by cyclic switching between lean and rich exhaust gases (LNT, NSC, NSR)
• • 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
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
  • B01J20/04—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising compounds of alkali metals, alkaline earth metals or magnesium
  • B01J20/041—Oxides or hydroxides
• • 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
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
  • B01J20/06—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising oxides or hydroxides of metals not provided for in group B01J20/04
• • 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
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
  • B01J20/10—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising silica or silicate
  • B01J20/103—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising silica or silicate comprising silica
• • 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
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
  • B01J20/28054—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their surface properties or porosity
  • B01J20/28057—Surface area, e.g. B.E.T specific surface area
• • 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
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/30—Processes for preparing, regenerating, or reactivating
  • B01J20/32—Impregnating or coating ; Solid sorbent compositions obtained from processes involving impregnating or coating
  • B01J20/3202—Impregnating or coating ; Solid sorbent compositions obtained from processes involving impregnating or coating characterised by the carrier, support or substrate used for impregnation or coating
  • B01J20/3204—Inorganic carriers, supports or substrates
• • 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
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/30—Processes for preparing, regenerating, or reactivating
  • B01J20/32—Impregnating or coating ; Solid sorbent compositions obtained from processes involving impregnating or coating
  • B01J20/3231—Impregnating or coating ; Solid sorbent compositions obtained from processes involving impregnating or coating characterised by the coating or impregnating layer
  • B01J20/3234—Inorganic material layers
  • B01J20/3236—Inorganic material layers containing metal, other than zeolites, e.g. oxides, hydroxides, sulphides or salts
• • 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
  • B01J23/32—Manganese, technetium or rhenium
  • B01J23/34—Manganese
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
  • B01J37/02—Impregnation, coating or precipitation
  • B01J37/024—Multiple impregnation or coating
  • B01J37/0244—Coatings comprising several layers
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
  • C01G25/00—Compounds of zirconium
  • C01G25/006—Compounds containing, besides zirconium, two or more other elements, with the exception of oxygen or hydrogen
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2255/00—Catalysts
  • B01D2255/20—Metals or compounds thereof
  • B01D2255/202—Alkali metals
  • B01D2255/2022—Potassium
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2255/00—Catalysts
  • B01D2255/20—Metals or compounds thereof
  • B01D2255/202—Alkali metals
  • B01D2255/2027—Sodium
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2255/00—Catalysts
  • B01D2255/20—Metals or compounds thereof
  • B01D2255/204—Alkaline earth metals
  • B01D2255/2042—Barium
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2255/00—Catalysts
  • B01D2255/20—Metals or compounds thereof
  • B01D2255/207—Transition metals
  • B01D2255/2073—Manganese
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2255/00—Catalysts
  • B01D2255/90—Physical characteristics of catalysts
  • B01D2255/902—Multilayered catalyst
  • B01D2255/9022—Two layers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2255/00—Catalysts
  • B01D2255/90—Physical characteristics of catalysts
  • B01D2255/92—Dimensions
  • B01D2255/9207—Specific surface
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • 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
  • B01J23/02—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the alkali- or alkaline earth metals or beryllium
• • 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
  • B01J23/10—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of rare earths
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2006/00—Physical properties of inorganic compounds
  • C01P2006/12—Surface area

Definitions

• the present invention relates to a compound which can be used as a Nox trap associating two compositions, the active phases of which are based on manganese and on another element chosen from alkalis, alkaline-earths and rare earths, and its use in the treatment of gases. exhaust
• NOx traps which are capable of oxidizing NO to NO2 and then adsorbing the O2 thus formed. Under certain conditions, the NO2 is released and then reduced to 2 by reducing species contained in the exhaust gases.
• NOx traps still have certain drawbacks. As a result of their aging, it has been observed that they tend to work only in a high temperature range and therefore have a reduced operating window It would therefore be advantageous to have a system capable of operating over a wider temperature range Furthermore, they are generally based on precious metals Gold, these metals are expensive and their availability can be problematic II would be also interesting to be able to have catalysts without precious metals to reduce costs
• the object of the invention is therefore the development of a compound which can be used in a wider range of temperatures and, optionally, in the absence of precious metal
• the compound of the invention which can be used as a NOx trap, is characterized in that it comprises a combination
• composition comprising a support and an active phase, the active phase being based on manganese and at least one other element A chosen from alkali and alkaline earth metals, manganese and element A being chemically related,
• a second composition comprising a support and an active phase based on manganese and at least one other element B chosen from alkali metals, alkaline earth metals and rare earths, this second composition having or being capable of having a specific surface of at least 10m / g after calcination 8 hours at 800 ° C
• rare earths is understood to mean the elements of the group constituted by ytt ⁇ um and the elements of the periodic classification with atomic number included inclusively between 57 and 71
• specific surface is understood to mean the BET specific surface area determined by nitrogen adsorption in accordance with standard ASTM D 3663-78 established on the basis of the BRUNAUER - EMMETT-TELLER method determined in the periodical "The Journal of the Amencan Chemical Society, 60, 309 (1938) "
• compositions comprise a support and an active phase
• support must be p ⁇ s in a broad sense to designate, in the composition, the majority of the element (s) and / or either without catalytic activity or proper trapping activity, or having a catalytic activity or trapping not equivalent to that of the active phase, and on which or on which the other elements are deposited
• support and active or supported phase we will speak in the following description of support and active or supported phase but it will be understood that we would not leave not within the scope of the present invention in the case where an element described as belonging to the active or supported phase was present in the support, for example by having been introduced into it during the preparation of the support itself
• the first composition is described below
• This composition comprises an active phase which is based on manganese and at least one other element A chosen from alkali metals and alkaline earth metals.
• alkaline element mention may be made more particularly of sodium and potassium As alkaline earth element, barium can in particular be mentioned.
• the composition may comprise one or more elements A, any reference below of the description in element A must therefore be understood as being able to also apply in the case where there are, several elements A
• the elements manganese and A are present in this first composition in a chemically bonded form.
• the elements manganese and A can be present in the form of a compound or of a phase of mixed oxide type
• This compound or this phase can in particular be represented by the formula A x Mn y ⁇ 2 ⁇ ⁇ (1) in which 0.5 ⁇ y / x ⁇ 6, the value of ⁇ depending on the nature of the element A and the oxidation state of manganese
• phase or compound of formula (1) there may be mentioned, by way of example, those of the vernadite, hollandite, romanechite or psilomelane, birnessite, todorokite, nozzle or lithiophonte type.
• the compound may optionally be hydrated. (1) is given here by way of illustration, it would not be departing from the scope of the present invention if
• the degree of oxidation of manganese can vary between 2 and 7 and, more particularly between 3 and 7
• this element and manganese can be present in the form of a compound of type K2Mn-4 ⁇ 8 In the case of barium, it can be a compound of type BaMn ⁇ 3
• the invention covers the case where the active phase of the first composition consists essentially of manganese and one or more other elements A chosen from alkali and alkaline earth metals, manganese and element A being chemically linked
• consists essentially is meant that the composition of the invention may have a NOx trap activity in the absence in the active phase of any element other than manganese and the element (s) A, such as for example an element of the precious metal or other metal type usually used in catalysis
• the first compositions further comprises a support.
• a support any porous support which can be used in the field of catalysis can be used. It is preferable that this support has chemical inertness with respect to the manganese elements and A sufficient to avoid a substantial reaction. of one or more of these elements with the support which would be likely to hinder the creation of a chemical bond between the manganese and the element A However, in the case of a reaction between the support and these elements, it is possible to implement more quantities important manganese and element A to obtain the desired chemical bond between these elements
• This support can be based on alumina Any type of alumina can be used HERE capable of having a specific surface sufficient for an application in catalysis Mention may be made of aluminas resulting from the rapid dehydration of at least one aluminum hydroxide, such as baye ⁇ te, hydrargillite or gibbsite, nordstrandite, and / or at least one aluminum oxyhydroxide such as boehmite, pseudoboehmite and diaspore
• a stabilized alumina As a stabilizing element, mention may be made of rare earths, barium, silicon, titanium and zirconium. As rare earth, mention may be made particularly of cerium, lanthanum or the lanthanum-neodymium mixture.
• the preparation of the stabilized alumina is carried out in a manner known per se, in particular by impregnating the alumina with solutions of salts, such as the nitrates of the abovementioned stabilizing elements or else by co-drying of an alumina precursor and of salts. of these elements then calcination
• the support can also be based on an oxide chosen from cerium oxide, zirconium oxide or their mixtures
• compositions based on a cerium oxide, a zirconium oxide and a ytt ⁇ um oxide, or even, in addition to the cerium oxide and zirconium oxide based on at least one other oxide chosen from scandium oxide and rare earth oxides with the exception of cerium, in a cerium / zirconium atomic ratio of at least 1
• These compositions have a specific surface after calcination for 6 hours at 900 ° C. of at least 35 m2 / g and an oxygen storage capacity at 400 ° C. of at least 1.5 ml of 02 g.
• the support is based on cerium oxide and it also comprises silica. Supports of this type are described in patent applications EP-A-207857 and EP-A -547924 whose teaching is incorporated HERE
• the total content of manganese, alkaline, and alkaline earth can vary within wide limits.
• the minimum content is that below which NOx adsorption activity is no longer observed.
• This content can be comp ⁇ se in particular between 2 and 50%, more particularly between 5 and 30%, this content being expressed in atomic% relative to the sum of the moles of oxide (s) of the support and the elements concerned of the phase active.
• the respective contents of manganese, alkaline, and alkaline-earth can also vary within wide proportions, the manganese content can be in particular equal to, or close to that of alkaline or alkaline-earth.
• the alkali is potassium in a content (as expressed above) which can be between 10 and 50% and more particularly between 30 and 50%.
• the first composition of the compound of the invention can be prepared by a process in which the support is brought into contact with the manganese and at least one other element A or with precursors of manganese and at least one other element A and where the whole is calcined at a temperature sufficient to create a chemical bond between the manganese and the element A.
• a method which can be used for the abovementioned contact is impregnation.
• a solution or a slip of salts is formed. or of compounds of the elements of the supported phase.
• salts one can choose the salts of inorganic acids such as nitrates, sulfates or chlorides. It is also possible to use the salts of organic acids and in particular the salts of saturated aliphatic carboxylic acids or the salts of hydroxycarboxylic acids. As examples, mention may be made of formates, acetates, propionates, oxalates or citrates. the support with the solution or the slip. More particularly dry impregnation is used. Dry impregnation consists in adding to the product to be impregnated a volume of an aqueous solution of the element which is equal to the pore volume of the solid to be impregnated. It may be advantageous to deposit the elements of the active phase in two stages. Thus, it is advantageously possible to deposit the manganese in a first step then the element A in a second.
• the support After impregnation, the support is optionally dried and then it is calcined It should be noted that it is possible to use a support which has not yet been calcined before impregnation
• the deposition of the active phase can also be done by atomization of a suspension based on salts or compounds of the elements of the active phase and of the support.
• the atomized product thus obtained is then calcined.
• the calcination is carried out, as indicated above, at a temperature sufficient to create a chemical bond between the manganese and the element A
• This temperature varies according to the nature of the element A but, in the case of calcination in air, it is generally at least 600 ° C. more particularly at least 700 ° C., it can in particular be between 800 ° C. and 850 ° C.
• composition also comprises a support and an active phase.
• active phase of the first composition also applies HERE, in particular as regards concerns the nature of the elements of this phase and their quantity
• element B can be more particularly sodium, potassium or barium
• the active phase of the second composition can also be based on manganese and at least one rare earth
• This rare earth can be more particularly chosen from cerium, terbium, gadolinium, sama ⁇ um, neodymium and praseodymium
• the content total manganese, alkaline, alkaline earth or rare earth may vary between 1 and 50%, more particularly between 5 and 30% This content is expressed in atomic% relative to the sum of the moles of oxide (s) of the support and of the elements concerned in the supported phase
• the respective manganese, alkaline, alkaline-earth or rare earth contents may also vary in large proportions, the manganese content may in particular be equal to, or close to that of element B
• the invention covers the case where the active phase consists essentially of manganese and one or more other elements B chosen from alkaline earths and rare earths.
• consists essentially is meant that the composition of the invention can have a NOx trap activity in the absence in the active phase of any element other than manganese and the element (s) B, such as for example an element of the precious metal type or other metal usually used in catalysis
• a characteristic of the second composition is that it has or is capable of having a specific surface of at least 10 m / g after calcination for 8 hours at 800 ° C. This specific surface can be
• this specific surface is at least 80 m / g and
• the specific surface is understood to mean the BET specific surface determined by nitrogen adsorption in accordance with standard ASTM D 3663-78 established on the basis of the method BRUNAUER - EMMETT- TELLER described in the periodical "The Journal of the American Chemical Society, 60, 309 (1938)"
• This surface characteristic is obtained by the choice of a suitable support having in particular a sufficiently high specific surface.
• This support can be based on alumina. Any type of alumina capable of having a specific surface sufficient for a catalysis application can be used here.
• the aluminas resulting from the rapid dehydration of at least one aluminum hydroxide may be mentioned, such as baye ⁇ te, hydrargillite or gibbsite, nordstrandite, and / or at least one aluminum oxyhydroxide such as boehmite, pseudoboehmite and diaspore
• a stabilized alumina is used.
• stabilizing element mention may be made of rare earths, barium, silicon and zirconium.
• rare earth mention may be made very particularly of cerium, lanthanum or the mixture lanthanum-neodymium
• the preparation of the stabilized alumina is carried out in a manner known per se, in particular by impregnating the alumina with solutions of salts, such as nitrates, of the abovementioned stabilizing elements or else by co-drying of an alumina precursor and of salts of these elements followed by calcination
• salts such as nitrates
• the ripening can be carried out by suspending the alumina in water then heating at a temperature comp ⁇ se for example between 70 and 110 ° C. After curing, the alumina is subjected to a heat treatment
• Another preparation consists of a
• the stabilizer content expressed by weight of stabilizer oxide relative to the stabilized alumina is generally between 1.5 and 15%, more particularly between 2.5 and 11%.
• the support can also be based on silica
• the alkoxylated compound can be chosen in particular from the products of formula (2) Rl - ((CH2) ⁇ -0) n -R2 in which Ri and R2 represent linear or non-linear alkyl groups, or H or OH or Cl or Br or I, n is a number between 1 and 100 and x is a number between 1 and 4, or those of formula (3) (R3, R-4) - ⁇ - ((CH2) ⁇ -0) n -
• R3 and R4 are identical or different substituents on this ring and represent hydrogen or linear or non-alkyl groups having from 1 to 20 carbon atoms, x and n being defined as above, or also those of formula (4) R4 ⁇ - ((CH2) ⁇ -O) nH where R4 represents a linear or non-linear alcohol group, having from 1 to 20 carbon atoms, x and n being defined as above, and those of formula (5) R5-S - ((CH2) ⁇ -O) n -H where R5 represents a linear or non-linear alkyl group having from 1 to 20 carbon atoms, x and n being defined as above
• R5-S - ((CH2) ⁇ -O) n -H where R5 represents a linear or non-linear alkyl group having from 1 to 20 carbon atoms, x and n being defined as above
• These supports can also be obtained by a second type of process which comprises a stage in which a solution of a cerium salt, a solution of a zirconium salt and an additive chosen from anionic surfactants, non-surfactants, are reacted.
• anionic surfactants carboxylates, phosphates, sulfates and sulfonates can be used more particularly.
• nonionic surfactants it is possible to use ethoxylated alkyl phenols and ethoxylated amines.
• the reaction between the zirconium and cerium salts can be carried out. by heating the solution containing the salts, it is then a thermohydrolysis reaction It can also be done by precipitation by introducing a base into the solution containing the salts
• the preparation of the second composition can be done with the same methods as those which were given above for the first. It will be noted that after bringing the support into contact with the elements of the active phase, the whole is calcined at a sufficient temperature for these elements to be present in the form of oxides Generally, this temperature is at least 500 ° C., more particularly at least 600 ° C.
• the compound of the invention as described above is in the form of a powder but it can optionally be shaped to be in the form of granules, beads, cylinders or honeycombs of variable dimensions
• the invention relates also a system, usable for trapping NOx, which comprises a coating (wash coat) with catalytic properties and incorporating the compound according to the invention, this coating being deposited on a substrate of the type, for example metallic or ceramic monolith.
• the system comprises a substrate and a coating consisting of two superposed layers.
• the first layer contains the first composition of the compound and the second layer contains the second composition L
• the order of the layers can be arbitrary, that is to say that the internal layer in contact with the substrate can contain either the first or the second composition, the external layer deposited on the first then containing the other composition of the compound
• the compound is present in the coating in the form of a single layer which in this case comprises the two aforementioned compositions, in the form of a mixture, obtained for example by mechanical mixing.
• the system comprises two juxtaposed substrates, each substrate comprising a coating
• the coating of the first substrate contains the first composition
• the coating of the second substrate contains the second composition
• the invention further relates to the use of a compound as described above in the manufacture of such a system
• the invention also relates to a gas treatment process with a view to reducing the emissions of nitrogen oxides using the compound of the invention.
• gases capable of being treated in the context of the present invention are, for example, those from gas turbines, boilers of thermal power plants or even internal combustion engines. In the latter case, it may especially be diesel engines or engines operating in lean mixture
• the compound of the invention functions as NOx traps when it is brought into contact with gases which have a high oxygen content.
• the value ⁇ is correlated with the air / fuel ratio in a manner known per se, in particular in the field of internal combustion engines.
• gases may be those of an engine operating in a lean burn mixture and which have an oxygen content (expressed by volume) for example of at least 2%, as well as those which have an even higher oxygen content, for example.
• oxygen content expressed by volume
• diesel engine gases that is to say at least 5% or more than 5%, more particularly at least 10%, this content being, for example, between 5% and 20%.
• gases of the above type which may also contain water in an amount of the order of 10% for example.
• the NOx trap evaluation test is carried out as follows:
• each of the NOx traps (first composition and second composition) in powder is loaded into a quartz reactor.
• the powder used has previously been compacted, then ground and sieved so as to isolate the particle size range between 0.125 and 0.250 mm.
• the reaction mixture at the inlet of the reactor has the following composition (by volume) - - NO: 300 vpm
• NO and NOx signals are given by an ECOPHYSICS NOx analyzer, based on the principle of chemiluminescence
• NOx traps The evaluation of NOx traps is carried out by determining the total amount of NOx adsorbed (expressed in mgNO / g of trap or active phase) until the trap phase is saturated The experiment is repeated at different temperatures between 250 ° C. and 500 ° C It is thus possible to determine the optimal temperature zone for the operation of the NOx traps
• Manganese nitrate Mn (N03) 2.4H 2 0 and potassium nitrate KNO3 99.5% are used
• the support used is of the type described in Example 4 of patent application WO 97/43214, that is to say a support based on cerium oxide, zirconium oxide and lanthanum oxide but in the respective proportions by weight relative to the oxides of 72/24/4
• This step consists in depositing the active element Mn in an amount equal to 10 atomic% and calculated as follows
• This step consists in depositing the second active element K in an amount of 10 atomic% and calculated as follows
• the operating protocol is as follows
• Manganese nitrate Mn (N03) 2.4H 2 0 and potassium nitrate KN03 99.5% are used
• the support used is an SB3 Condea alumina which has been stabilized by impregnation with 10 atomic% of Ce and then calcination for 2 hours at 500 ° C.
• the procedure is carried out in two stages for the deposition in the same manner as for the first composition (dry impregnation, pore volume of the support determined with water of 0.8 cm 3 / g) with the elements Mn and K in the same quantities, the first calcination taking place at 500 ⁇ C and the second at 800 ° C.
• the composition thus obtained has a BET surface area of 117 m 2 / g.
• NOx trap activity is therefore observed over the entire temperature range between 250 ° C. and 500 ° C. This activity takes place in the absence of precious metal.

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• 2000
  • 2000-05-05 CN CN008084165A patent/CN1131726C/zh not_active Expired - Fee Related
  • 2000-05-05 KR KR1020017014219A patent/KR20020042528A/ko not_active Application Discontinuation
  • 2000-05-05 MX MXPA01011243A patent/MXPA01011243A/es not_active Application Discontinuation
  • 2000-05-05 WO PCT/FR2000/001227 patent/WO2000067904A1/fr active Search and Examination
  • 2000-05-05 CA CA002373080A patent/CA2373080A1/fr not_active Abandoned
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  • 2000-05-05 AU AU44138/00A patent/AU4413800A/en not_active Abandoned
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