Synthesis of a catalyst comprising an IZM-10 AEI zeolite and at least one transition metal for the selective reduction of NOX

Abstract

The invention relates to a catalyst for the selective reduction of NOx, based on an IZM-10 AEI zeolite and at least one transition metal, and to its preparation method comprising at least mixing, in an aqueous medium, a FAU-type zeolite having a SiO2 (FAU) / AI2O3(FAU) molar ratio of between 10 and 60 inclusive and a mass percentage of sodium in cation form of less than 0.005%, a nitrogen-containing organic compound R, wherein R is (6R,10S)-6,10-dimethyl-5-azoniaspiro[4,5]decane in its hydroxide form, and optionally sodium hydroxide, until a homogeneous precursor gel is obtained; ii) a hydrothermal treatment step; iii) a step of exchanging at least one ion with a solution comprising at least one species capable of releasing a transition metal; iv) a heat treatment step by drying and calcination.

Description

[0001] SYNTHESIS OF A CATALYST COMPRISING AN IZM-10 ZEOLITE OF AEI STRUCTURAL TYPE AND AT LEAST ONE TRANSITION METAL FOR THE SELECTIVE REDUCTION OF NOx

[0002] TECHNICAL FIELD

[0003] The subject of the invention is a process for preparing a catalyst based on an IZM-10 zeolite of structural type AEI and at least one transition metal, the catalyst prepared or capable of being prepared by the process, and its use for the selective catalytic reduction of NOx in the presence of a reducing agent, in particular for the combustion gases of internal combustion engines.

[0004] PRIOR TECHNIQUE

[0005] Nitrogen oxide (NOx) emissions resulting from combustion are a major concern for society as they are responsible for health problems, ground-level ozone, acid rain and smog. Increasingly stringent standards are being implemented by government bodies to limit the impact on the environment and health. Highly efficient pollution control systems such as three-way catalysts or selective catalytic reduction catalysts, designated by the English acronym "SCR" for "Selective Catalytic Reduction", have therefore been developed to equip means of transport in order to achieve these objectives. Selective catalytic reduction is carried out using a reducing agent, generally ammonia, and can therefore be referred to as NH3-SCR.The ammonia (NH3) involved in the SCR process is generally generated via the decomposition of an aqueous urea solution (e.g., a commercial AdBlue or DEF-type solution), and produces N2 and H2O upon reaction with NOx.

[0006] Transition metal-exchanged zeolites are used in particular as catalysts for NH3-SCR applications in transport. Small-pore zeolites, particularly of the AEI and CHA structural type exchanged with copper, are particularly suitable.

[0007] Zeolites of the AEI structural type include in particular the SSZ-39 zeolite (Wagner, P et al., J. Am. Chem. Soc., 122, 263-273 (2000)), and the zeotypes ALPO-18 (Simmen, A. et al., Zeolites, 11, 654-661 (1991)) and SAPO-18 (Chen, JS et al., Catalysis Letters, 28, 241-248 (1994)). The "AEI" structural type is defined by the "Structure Commission" of the International Zeolite Association (IZA).

[0008] AEI structural type zeolites have a three-dimensional system of pores delimited by eight TO4 tetrahedra and obtained by the three-dimensional connection of double cycles of T atoms (D6R) or T can be silicon, aluminum or phosphorus. Many methods for synthesizing AEI structural type zeolites are known. They require the simultaneous use of an organic structuring agent and an inorganic base (sodium or potassium hydroxide). To obtain the protonated form of the zeolite, it is necessary to carry out an ion exchange step with NH4NO3, NH4Cl, ammonium acetate or any other aqueous source of ammonium cations.

[0009] Patent application CN 112758954 presents the synthesis of a core-layer SSZ-39 zeolite where the core contains copper. The synthesis is carried out in the presence of sodium or potassium hydroxide in the presence of an organic structuring agent chosen from the ions of: N,N- diethyl I-2 , 6-dimethyl I pi peridine, 1 , 1 , 3,5-tetramethylpiperidine, 2,6-dimethyl-5-azoniumspiro- [4,5]-decane, N,N-diethyl-2-ethylpiperidine, N-ethyl-N-propane-2,6-dimethylpiperidine, N-methyl-N-ethyl-2,6-dimethylpiperidine, N-methyl-N-ethyl-2-ethylpiperidine, 2,5-dimethyl-N,N- diethylpyrrole, 2,6-dimethyl-N,N-dimethylpiperidine, 3,5-dimethyl-N,N-dimethylpiperidine, 2- Ethyl-N,N-dimethylpiperidine, 2,2,6,6-Tetramethyl-N-methyl-N-ethylpiperidine, N-cyclooctyl-pyridine, 2,2,6,6-tetramethyl-N,N-dimethylpiperidine and N,N-dimethyl-N,N-bicyclononane, preferably the organic structuring agent is chosen from: N,N-diethyl-2,6-dimethylpiperidine and / or 3,5-dimethyl-N,N-dimethylpiperidine.The molar ratio Na2O(NaOH) / SiO2 in the synthesis mixture is between 0.05 and 0.25. To obtain the protonated form of the zeolite, it is necessary to carry out an ion exchange step with NH4NO3.

[0010] Patent application US2022106192 presents the synthesis of a zeolite of structural type AEI in the presence of an organic structuring agent of N,N-dialkyl-dialkylpiperidinium cation type of N,N-(C1-C3)-dialkyl-(C1-C3)-dialkylpiperldinium cation, preferably an N,N-(C1-C2)-dialkyl-(C1-C3)-dialkylpiperldinium cation, preferably the N,N-diethyl-2.6-dimethylpiperidinium cation, more preferably the N,N-diethyl-cis-2.6-dimethylpiperidinium cation. The synthesis of the zeolite is carried out in the presence of sodium hydroxide in addition to any other source of Na cations. The molar ratio Na2O(NaOH) / SiC>2 in the synthesis mixture is between 0.25 and 1. Preferably, the synthesis gel does not contain a zeolite of the FAU structural type. To obtain the protonated form of the zeolite, it is necessary to carry out an ion exchange step with NH4NO3.

[0011] The article “Hydrothermal Conversion of Titanated FAU to AEI Zeolite and Its Enhanced Catalytic Performance for NOx Reduction” (Adv. Porous Mater. 2016, VOL 4, No. 1, 62) presents the synthesis of an AEI zeolite using [Al, Ti] FAU zeolite as a source of silicon and aluminum in the presence of sodium hydroxide and the organic structuring agent: 1,1-diethyl-2,6-dimethylpiperidinium hydroxide (DEDMPOH). The molar ratio Na2O(NaOH) / SiO2 in the synthesis mixture is 0.1. To obtain the protonated form of the zeolite, it is necessary to carry out an ion exchange step with NH4NO3. Patent application CN105314646A presents the synthesis of a zeolite of structural type AEI in the presence of an organic structuring agent chosen from the cations: 1-methyl-2,6-dimethyl-piperidine, 1-ethyl-2,6-dimethyl-piperidine, 1-methyl-3,5-dimethyl-piperidine, 1,1-dimethyl-2,6-dimethyl-piperidine, 1,1-diethyl-2,6-dimethyl-piperidine,

[0012] 1,1-dimethyl-3,5-dimethyl-piperidine, 1-ethyl-3,5-dimethyl-piperidine, 1,1-bis-ethyl-2,6-dimethyl-piperidine, 1,1-diethyl-3,5-dimethyl-piperidine. The synthesis of zeolite of structural type AEI is carried out in the presence of sodium or potassium hydroxide. The molar ratio Na2O( Na oH) / SiO2 in the synthesis mixture is between 0.1 and 0.5. To obtain the protonated form of the zeolite it is necessary to carry out an ion exchange step with NH4NO3.

[0013] Patent application CN107285333A presents the synthesis of a zeolite of structural type AEI using microwaves and in the presence of an organic structuring agent chosen from the cations: 1,1,2,2,6,6-hexamethylpiperidinium, 1,1,2,2,6,6-hexamethyl-4-oxo-piperidinium, 1,1,3,5-tetramethyl-4-oxo-piperidine, 1-hydroxy-1,1,2,2,6,6-hexamethylpiperidinium, 1,1-dimethyl-4,4-propoxypiperidinium, 3,5-dimethoxy-1,1-dimethyl piperidinium, 3,5-dihydroxy-

[0014] 1,1-dimethyl piperidinium, 4-ethyl-1,1-dimethyl-3,5-dioxo-pyridinium, 1-ethyl-1-methyl-2,2,6-methyl-piperidine, 1-epoxy-propyl-1-methyl-2,2,6,6-hexamethylpiperidinium. The synthesis of zeolite of structural type AEI is carried out in the presence of sodium or potassium hydroxide. The molar ratio Na2O(NaOH) / SiO2 in the synthesis mixture is between 0.1 and 0.5.

[0015] Patent application CN107308980A presents the use of a zeolite of structural type AEI containing copper in NH3-SCR. The synthesis of the zeolite of structural type AEI is carried out in the presence of sodium hydroxide and an organic structuring agent chosen from the cations: 1,1,2,2,6,6-hexamethylpiperidinium, 1,1,2,2,6,6-hexamethyl-4-oxo-piperidinium, 1,1,3,5-tetramethyl-4-oxo-piperidine, 1-hydroxy-1,1,2,2,6,6-hexamethylpiperidinium, 1,1-dimethyl-4,4-propoxypiperidinium, 3,5-dimethoxy-1,1-dimethyl piperidinium, 3,5-dihydroxy-

[0016] 1,1-dimethyl piperidinium, 4-ethyl-1,1-dimethyl-3,5-dioxo-pyridinium, 1-ethyl-1-methyl-2,2,6-methyl-piperidine, 1-epoxy-propyl-1-methyl-2,2,6,6-hexamethylpiperidinium. The molar ratio Na2O(NaOH) / SiC>2 in the synthesis mixture is between 0.1 and 0.5.

[0017] Patent US5958370 presents the synthesis of a SSZ-39 zeolite of AEI structural type in the presence of sodium hydroxide and an organic structuring agent chosen from the cations: N,N-Diethyl-2,6-dimethylpiperidinium, N,N-Dimethyl-9-azoniabicyclo[3. 3. 1]nonane, N,N-Dimethyl- 2,6-dimethylpiperidinium, N-Ethyl-N-methyl-2,6-dimethylpiperidinium, N,N-Diethyl-2- ethylpiperidinium, N,N-Dimethyl-2-(2-hydroxyethyl)piperidinium, N,N-Dimethyl-2- ethylpiperidinium, N,N-Dimethyl-3,5-dimethylpiperidinium, N-Ethyl-N-methyl-2- ethylpiperidinium, 2,6-Dimethyl-1-Azonium[5.4]decane, N-Ethyl-N-propy1-2,6- dimethylpiperidinium, 2,2,4,6,6-Pentamethyl-2-azoniabicyclo[3.2.1]octane, N,N-Diethyl-2,5-dimethyl-2,5-dihydropyrrolium. The molar ratio Na2O(NaOH) / SiC>2 in the synthesis mixture is between 0.3 and 1. The synthesis times are greater than 6 days. According to this patent the structuring agents: N,N-Dimethyl-2-ethylpiperidinium, N-Ethyl-N-methyl-2-ethylpiperidinium, 2,6-Dimethyl-1-Azonium[5.4]decane and N-Ethyl-N-propyl-2,6-dimethylpiperidinium do not allow to obtain a pure SSZ-39 zeolite of AEI structural type, analcime impurities are present. To obtain the protonated form of the zeolite it is necessary to carry out an ion exchange step with NH4NO3.

[0018] Patent application US2017128921 presents the synthesis of a zeolite of structural type AEI in the presence of sodium hydroxide and an organic structuring agent chosen from the cations: N,N-dimethyl-3,5-dimethylpiperidinium, N,N-dimethyl-2-(2-hydroxyethyl)piperidinium, N,N-dimethyl-2-ethylpiperidinium and 2,2,4,6,6-pentamethyl-2-azoniabycyclo[3.2.1]octane. The molar ratio Na2O(NaOH) / SiC>2 in the synthesis mixture is between 0.2 and 1. To obtain the protonated form of the zeolite, it is necessary to carry out an ion exchange step with ammonium acetate.

[0019] The article “Transformation synthesis of aluminosilicate SSZ-39 zeolite from ZSM-5 and beta zeolite” (J. Mater. Chem. A, 2019, 7, 4420) presents the synthesis of an SSZ-39 zeolite of structural type AEI by interzeolitic transformation in the presence of the organic structuring agent N,N-diethyl-cis-2,6-dimethylpiperidine hydroxide and sodium hydroxide. The molar ratio Na2O(NaOH) / SiO2 in the synthesis mixture is 0.17. To obtain the protonated form of the zeolite, it is necessary to carry out an ion exchange step with NH4NO3.

[0020] The article “Synthesis of high-silica AEI zeolites with enhanced thermal stability by hydrothermal conversion of FAU zeolites, and their activity in the selective catalytic reduction of NOx with NH3 (J. Mater. Chem. A, 2015, 3, 857) presents the synthesis of a zeolite of the AEI structural type by interzeolitic transformation in the presence of the organic structuring agent tetraethylphosphonium in fluoride medium. This synthesis makes it possible to obtain a zeolite of the AEI structural type more stable at high temperature than that obtained with the organic structuring agent N,N-diethyl-2,6-dimethylpiperidinium in basic medium. The molar ratio Na2O( Na oH) / SiO2 in the synthesis mixture is 0.05. To obtain the protonated form of the zeolite, it is necessary to carry out an ion exchange step with NH4Cl.

[0021] Patent application US2018093257 presents the synthesis of a JMZ-8 zeolite of structural type AEI in the presence of sodium hydroxide and an organic structuring agent R chosen from N,N-diethyl-cis-2,6-dimethylpiperidinium or NN-Dimethyl-3.5-dimethylpiperidinium. The molar ratio Na2O(NaOH) / AhO3 in the synthesis mixture is between 0.5 and 2. The purity of the AEI zeolite obtained is greater than 90%. To obtain the protonated form of the zeolite, it is necessary to carry out an ion exchange step with NH4NO3. Patent application LIS2018093256 presents the synthesis of a JMZ-9 zeolite of structural type AEI in the presence of an organic structuring agent R chosen from N,N-diethyl-cis-2,6-dimethylpiperidinium or NN-Dimethyl-3.5-dimethylpiperidinium or the mixture of the two. The claimed molar ratios are: (SiO 2) ) / (AI2O3) between 20 and 50, H2O / SiO2 between 10 and 40, R / SiO2 between 0.25 and 1, HO7SiO2 between 0.25 and 1,

[0022] Patent application US2020-0360906A1 presents the synthesis of a JMZ-8 zeolite of structural type AEI in the presence of sodium hydroxide and an organic structuring agent R chosen from N,N-diethyl-cis-2,6-dimethylpiperidinium or NN-Dimethyl-3.5-dimethylpiperidinium. The molar ratio Na2O(NaOH) / AI2C>3 in the synthesis mixture is between 0.5 and 2. The purity of the AEI zeolite obtained is greater than 90%. To obtain the protonated form of the zeolite, it is necessary to carry out an ion exchange step with NH4NO3.

[0023] Patent application WO2016 / 166245 presents the synthesis of a zeolite of structural type AEI in the presence of sodium hydroxide and an organic structuring agent chosen from: NN-Dimethyl-3.5-dimethylpiperidinium, N,N-diethyl-2,6-dimethylpiperidinium (DEDMP), N,N-dimethyl-2,6-dimethylpiperidinium, N-ethyl-N-methyl-2,6-dimethylpiperidinium alone or in a mixture. The molar ratio Na2O(NaOH) / AI2C>3 in the synthesis mixture is between 0.001 and 2. To obtain the protonated form of the zeolite, it is necessary to carry out an ion exchange step with NH4NO3.

[0024] SUMMARY OF THE INVENTION

[0025] The applicant has discovered that it is possible to directly prepare a catalyst based on a so-called IZM-10 zeolite of AEI structural type obtained directly in at least partially protonated form and that a catalyst based on an IZM-10 zeolite of AEI structural type prepared according to a particular synthesis method and at least one transition metal, in particular copper, has interesting NOx conversion performance. For the purposes of the present invention, the term "partially protonated" means an AEI zeolite comprising an AI2O3 / Na2O molar ratio of between 100 and 400, and "fully protonated" means an AEI zeolite comprising an AI2O3 / Na2O molar ratio of greater than 400. The process for synthesizing the catalyst according to the invention thus makes it possible to dispense with the additional step of ion exchange with ammonium nitrate while ensuring better exchange with the transition metal.The NOx conversion performance is improved, in particular the initiation temperatures are notably lower than those obtained with prior art catalysts, such as catalysts based on zeolite of the CHA or AEI structural type exchanged with copper, while presenting lower nitrous oxide N2O emissions. This catalyst also presents a high thermal and hydrothermal stability.The invention relates to a process for preparing a catalyst based on a zeolite, which can be designated by the term "IZM-10" of structural type AEI and at least one transition metal comprising at least the following steps: i) mixing in an aqueous medium, a zeolite of structural type FAU having a molar ratio SiC>2 (FAU AI2O3 (FAU) of between 10 and 60, limits included and a mass percentage of sodium in cationic form of less than 0.005%, of a nitrogenous organic compound R, R being (6R,10S)-6,10-dimethyl-5-azoniaspiro[4,5]decane in its hydroxide form and optionally sodium hydroxide, the reaction mixture having the following molar composition:.

[0026] -(SiC>2 (FAU)) / (AhO3 (FAU)) between 10 and 60, preferably between 30 and 50

[0027] -H2O / (SiC>2 (FAU)) between 20 and 60, preferably between 30 and 50

[0028] -R / (SiC>2 (FAU)) between 0.05 and 0.70, preferably between 0.15 and 0.60

[0029] -Na2O (NaOH) / (SiC>2 (FAU)) between 0 and 0.20, preferably between 0 and 0.15

[0030] -Na2O (FAU) / (SiC>2 (FAU)) between 3.5*10 -5 and 7*10 -5 , preferably between 4*10 -5 and 6*10 -5in which Na2O (FAU) denotes the quantity of Na2O provided by the FAU zeolite, Na2O (NaOH) denotes the quantity of Na2O provided by the soda, SiC>2 (FAU) denotes the quantity of SiC>2 provided by the FAU zeolite, and AI2C>3 (FAU) denotes the quantity of AI2O3 provided by the FAU zeolite, until a homogeneous precursor gel is obtained; ii) the hydrothermal treatment of said precursor gel obtained at the end of step i) at a temperature of between 120°C and 220°C, for a period of between 12 hours and 7 days until an AEI zeolite is obtained; iii) at least one ion exchange comprising bringing said zeolite obtained at the end of the previous step into contact with a solution comprising at least one species capable of releasing a transition metal, in solution in reactive form with stirring at room temperature for a period of between 1 hour and 2 days;iv) a heat treatment by drying the solid obtained at the end of the previous step at a temperature between 20 and 150°C followed by at least one calcination under air flow at a temperature between 400 and 700°C for a duration between 8 and 24 hours.;

[0031] The term “IZM-10” is the designation chosen by the inventors for the new zeolite obtained in particular by this process.

[0032] Steps iii) and iv) may be repeated.

[0033] Said transition metal released in the exchange solution of step iii) may be selected from the group formed by the following elements: Ti, V, Mn, Mo, Fe, Co, Cu, Cr, Zn, Nb, Ce, Zr, Rh, Pd, Pt, Au, W, Ag, preferably from the group formed by the following elements: Fe, Cu, Nb, Ce or Mn, more preferably from Fe, Ce or Cu, alone or in a mixture and even more preferably said transition metal is Cu or Fe.

[0034] The SiC^ / AhCh molar ratio of the AEI zeolite is advantageously between 10 and 60, preferably between 12 and 50, limits included, and the AI2C>3 / Na2O molar ratio of the AEI zeolite is advantageously greater than 100 and preferably greater than 400,

[0035] The FAU structural type zeolite can have a SiCh / AhCh molar ratio between 20 and 50, inclusive, and a mass percentage of Na2O less than 0.0048%.

[0036] In one embodiment, no sodium hydroxide is added to the reaction mixture of step i) (Na2O( Na oH) / (SiO2 <FAU)) = 0).

[0037] Crystalline seeds of a zeolite of structural type AEI can be added to the reaction mixture of step i), preferably in an amount of between 0.01 and 10% by weight relative to the total mass of the sources of tetravalent and trivalent elements in anhydrous form present in said mixture, said crystalline seeds not being taken into account in the total mass of the sources of SiO2 and AI2O3.

[0038] Step i) may comprise a step of maturing the reaction mixture at a temperature of between 20 and 100°C, with or without stirring, for a period of between 30 minutes and 48 hours.

[0039] The hydrothermal treatment of step ii) may be carried out under autogenous pressure at a temperature between 120°C and 220°C, preferably between 150°C and 200°C, even more preferably between 160°C and 195°C, for a duration between 12 hours and 7 days, preferably between 12 hours and 6 days.

[0040] The solid phase obtained at the end of step ii) can be filtered, washed, and dried at a temperature between 20 and 150°C, preferably between 60 and 100°C, for a period of between 5 and 24 hours to obtain a dried zeolite.

[0041] The dried zeolite can then be calcined at a temperature between 450 and 700°C for a period of between 2 and 20 hours, the calcination being able to be preceded by a gradual increase in temperature.

[0042] The content of transition metal(s) introduced by the ion exchange step iii) may be between 0.5 and 6% by mass, preferably between 0.5 and 5% by mass, more preferably between 1 and 4% by mass, relative to the total mass of the final anhydrous catalyst.

[0043] The invention also relates to a catalyst for the selective reduction of NOx capable of being obtained by the preparation process according to any one of its variants comprising: - a zeolite of structural type AEI with a SiC^ / AhOs molar ratio of between 10 and 60, limits included, and of purity greater than or equal to 98% by weight, preferably greater than or equal to 99% by weight;

[0044] -and 0.5 to 6% of a transition metal, preferably copper or iron,

[0045] The invention also relates to a method for selective reduction of NO X by a reducing agent such as NH3 or H2 using the catalyst previously described or the catalyst directly obtained by the preparation process according to any of its variants for the selective reduction of NO X by a reducing agent such as NH3 or H2.

[0046] The catalyst may be formed by deposition as a coating, on a honeycomb structure or a plate structure, or said catalyst is in the form of an extrudate or bead, containing up to 100% of said catalyst.

[0047] The honeycomb structure can be formed of parallel channels open at both ends or have porous filtering walls for which adjacent parallel channels are alternately blocked on either side of the channels.

[0048] The quantity of catalyst deposited on said structure can be between 40 and 250 g / L for filter structures and between 60 and 300 g / L for structures with open channels.

[0049] The catalyst may be combined with a binder such as ceria, zirconium oxide, alumina, non-zeolitic silica-alumina, titanium oxide, a mixed oxide of ceria-zirconia type, a tungsten oxide and / or a spinel to be shaped by deposition in the form of a coating, said coating preferably being able to be combined with another coating having capacities for adsorbing pollutants, in particular NOx, for reducing pollutants, in particular NOx, or promoting the oxidation of pollutants.

[0050] Said catalyst can be integrated:

[0051] - in an exhaust line of an internal combustion engine operating on carbonaceous or non-carbonaceous fuels, or

[0052] - in a reactor to treat industrial fumes.

[0053] LIST OF FIGURES

[0054] Figure 1 represents the chemical formula of the organic nitrogen compound (6R,10S)-6,10-dimethyl-5-azoniaspiro[4,5]decane in its hydroxide form used in the synthesis process according to the invention.

[0055] Figure 2 represents the conversion C in % obtained during a catalytic test for the reduction of nitrogen oxides (NOx) by ammonia (NH3) in the presence of oxygen (O2) as a function of the temperature T in °C, for the catalysts synthesized according to examples 2, 3 and 4, CuIZM-10 curve symbolized by triangles, CuCHA, comparative, curve symbolized by circles and CuAEI, comparative, curve symbolized by squares.

[0056] Figure 3 represents the conversion C in % obtained during a catalytic test for the reduction of nitrogen oxides (NOx) by ammonia (NH3) in the presence of oxygen (O2) as a function of the temperature T in °C, the curves marked by squares and crosses corresponding respectively to the tests carried out with the catalysts synthesized according to example 6 (FelZM-10) and example 7 (FeAEI).

[0057] Other characteristics and advantages of the synthesis process according to the invention, of the catalyst according to the invention and of the use according to the invention, will appear on reading the following description of non-limiting examples of embodiments, with reference to the figures appended and described below.

[0058] DESCRIPTION OF EMBODIMENTS

[0059] Preparation process

[0060] The invention relates to a process for preparing a catalyst based on an IZM-10 zeolite of AEI structural type and at least one transition metal comprising at least the following steps:

[0061] Step i) of mixing:

[0062] Step i) comprises mixing in an aqueous medium, a zeolite of structural type FAU having a molar ratio SiO2 (FAU ALOS <FAU) compris entre 10 et 60, bornes incluses et un pourcentage massique de sodium sous forme cationique inférieur à 0,005%, d’un composé organique azoté R, R étant le (6R,10S)-6,10-diméthyl-5-azoniaspiro[4,5]décane sous sa forme hydroxyde et éventuellement de la soude, le mélange réactionnel présentant la composition molaire suivante :

[0063] (SiC>2 (FAU)) / (AhO3 (FAU)) between 10 and 60, preferably between 30 and 50

[0064] H2O / (SiC>2 (FAU)) between 20 and 60, preferably between 30 and 50

[0065] R / (SiC>2 (FAU)) between 0.05 and 0.70, preferably between 0.15 and 0.60

[0066] Na2O( Na oH) / (SiO2 (FAU)) between 0 and 0.20, preferably between 0 and 0.15

[0067] Na2Û (FAU) / (SiC>2 (FAU)) between 3.5*10 -5 and 7*10 -5 , preferably between 4*10 -5 and 6*10 -5 in which Na2O (FAU) denotes the quantity of Na2O provided by the FAU zeolite, Na2O (NaOH) denotes the quantity of Na2O provided by the soda, SiC>2 (FAU) denotes the quantity of SiC>2 provided by the FAU zeolite, and ALOS ^AU) denotes the quantity of AI2O3 provided by the FAU zeolite, until a homogeneous precursor gel is obtained. Advantageously, the SiO2 / AI2C>3 molar ratio of the AEI zeolite obtained can be between 10 and 60, preferably between 12 and 50, limits included.

[0068] The zeolite of structural type FAU used in the reaction mixture of step i) has a molar ratio SiO2 / AI2C>3 of between 10 and 60, preferably of between 20 and 50, limits included, and a mass percentage of Na2O of less than 0.005%, preferably less than 0.048%.

[0069] The low amount of sodium in the starting FAU zeolite helps to minimize the sodium content in the synthesis reaction mixture while facilitating zeolitization towards a zeolite of AEI structural type, and the AEI zeolite is thus obtained in at least partially protonated form.

[0070] For the purposes of the present invention, the term “partially protonated” means an AEI zeolite comprising an AI2O3 / Na2O molar ratio of between 100 and 400, and “fully protonated” means an AEI zeolite comprising an AI2O3 / Na2O molar ratio of greater than 400.

[0071] A ratio of Na2O(NaOH) / (SiO2 <fau>) = 0 means that no sodium hydroxide is added to the synthesis gel, which makes it possible to obtain the AEI zeolite in protonated form directly.

[0072] Crystalline seeds of a zeolite of structural type AEI can be added to the reaction mixture of step i), preferably in an amount of between 0.01 and 10% by weight relative to the total mass of the sources of tetravalent and trivalent elements in anhydrous form present in said mixture, said crystalline seeds not being taken into account in the total mass of the sources of SiO2 and AI2O3.

[0073] Step i) may comprise a step of maturing the reaction mixture at a temperature of between 20 and 100°C, with or without stirring, for a period of between 30 minutes and 48 hours.

[0074] Step ii) of hydrothermal treatment:

[0075] A hydrothermal treatment of said precursor gel obtained at the end of step i) is carried out at a temperature between 120°C and 220°C, for a period between 12 hours and 7 days.

[0076] The hydrothermal treatment of step ii) can be carried out under autogenous pressure at a temperature between 120°C and 220°C, preferably between 150°C and 200°C, even more preferably between 160°C and 195°C, for a duration between 12 hours and 7 days, preferably between 12 hours and 6 days.

[0077] The solid phase obtained at the end of step ii) can be filtered, washed, and dried at a temperature of between 20 and 150°C, preferably between 60 and 100°C, for a period of between 5 and 24 hours to obtain a dried zeolite. The dried zeolite can then be calcined at a temperature of between 450 and 700°C for a period of between 2 and 20 hours, the calcination possibly being preceded by a gradual increase in temperature.

[0078] The zeolite of structural type AEI with a molar ratio SiC^ / AhOs between 10 and 60, inclusive, obtained by the preparation process described above, advantageously exhibits the following significant X-ray diffraction lines:

[0079] Table 1 where FF = very strong; F = strong; m = medium; mf = medium weak; f = weak; ff = very weak. The relative intensity l rei is given in relation to a relative intensity scale where a value of 100 is assigned to the most intense line in the X-ray diffraction pattern: ff <15; 15 <f <30 ; 30 < mf <50 ; 50 <m < 65 ; 65 <F < 85 ; FF >85; and a purity greater than or equal to 98%, preferably greater than or equal to 99% by weight, as well as an AhOs / IX^O molar ratio greater than 100 and preferably greater than 400. Step iii) of ion exchange: Step iii) includes at least one ion exchange comprising bringing said zeolite obtained at the end of the previous step into contact with a solution comprising at least one species capable of releasing a transition metal, in particular copper, in solution in reactive form with stirring at room temperature for a period of between 1 hour and 2 days.

[0080] Said transition metal released in the exchange solution of step iii) may be selected from the group formed by the following elements: Ti, V, Mn, Mo, Fe, Co, Cu, Cr, Zn, Nb, Ce, Zr, Rh, Pd, Pt, Au, W, Ag, preferably from the group formed by the following elements: Fe, Cu, Nb, Ce or Mn, more preferably from Fe, Ce or Cu, alone or in a mixture and even more preferably said transition metal is Cu.

[0081] The content of transition metal(s) introduced by the ion exchange step iii) is advantageously between 0.5 and 6% by mass, preferably between 0.5 and 5% by mass, more preferably between 1 and 4% by mass, relative to the total mass of the final anhydrous catalyst.

[0082] Step iv) heat treatment:

[0083] Step iv) comprises a heat treatment by drying the solid obtained at the end of the previous step at a temperature between 20 and 150°C followed by at least one calcination under air flow at a temperature between 400 and 700°C for a duration between 8 and 24 hours.

[0084] Steps iii) and iv) may optionally be repeated, for example to increase the metal content.

[0085] The catalyst

[0086] The catalyst according to the invention comprises at least one IZM-10 zeolite of AEI type, and at least one additional transition metal, preferably copper.

[0087] According to the invention, the transition metal or metals included in the catalyst is (are) selected from the elements from the group formed by the elements of groups 3 to 12 of the periodic table of elements including the lanthanides.

[0088] In particular, the transition metal or metals included in the catalyst is (are) selected from the group formed by the following elements: Ti, V, Mn, Mo, Fe, Co, Cu, Cr, Zn, Nb, Ce, Zr, Rh, Pd, Pt, Au, W, Ag, preferably from the group formed by the following elements: Fe, Cu, Nb, Ce or Mn, more preferably from Fe, Ce or Cu alone or in a mixture and even more preferably said transition metal is Cu.

[0089] In the catalyst according to the invention, the content of transition metal(s), in particular copper, is between 0.5 and 6% by mass, preferably between 0.5 and 5% by mass, more preferably between 1 and 4% relative to the total mass of the final anhydrous catalyst. Characterization of the catalyst prepared according to the invention

[0090] X-ray diffraction makes it possible to verify that the solid obtained by the process according to the invention is indeed a zeolite of structural type AEI. The purity obtained is advantageously greater than 98% and preferably greater than or equal to 99% by weight, even more preferably greater than or equal to 99.8% by weight.

[0091] This diffraction pattern is obtained by X-ray crystallographic analysis using a diffractomer using the classical powder method with copper Kai radiation (X = 1.5406Â). From the position of the diffraction peaks represented by the angle 20, the characteristic reticular equidistances dhki of the sample are calculated using the Bragg relation. The measurement error A(d h ki) on dhki is calculated using the Bragg relation as a function of the absolute error A(20) assigned to the measurement of 20. An absolute error A(20) equal to ± 0.02° is commonly accepted in Angstroms (Â). Each of these values ​​must be assigned the measurement error A(dhki) between ± 0.6Â and ± 0.01Â.

[0092] X-ray fluorescence (FX) spectrometry is a chemical analysis technique that uses a physical property of matter, X-ray fluorescence. It allows the analysis of most chemical elements from Beryllium (Be) in concentration ranges from a few ppm to 100%, with accurate and reproducible results. X-rays are used to excite the atoms in the sample, causing them to emit X-rays with energies characteristic of each element present. The intensity and energy of these X-rays are then measured to determine the concentration of the elements in the material.

[0093] The loss on ignition (LAI) of the catalyst obtained after the drying step (and before calcination) or after the calcination step of step iv) of the process according to the invention is generally between 5 and 25% by weight. The loss on ignition of a sample, designated by the acronym LAI, corresponds to the difference in mass of the sample before and after a heat treatment at 1000°C for 2 hours. It is expressed in % corresponding to the percentage loss of mass. The loss on ignition generally corresponds to the loss of solvent (such as water) contained in the solid but also to the elimination of organic compounds contained in the mineral solid constituents.

[0094] Process for the selective reduction of NOx by a reducing agent such as NH3 using the catalyst according to the invention

[0095] The invention also relates to the use of the catalyst according to the invention, directly prepared or capable of being prepared by the process described above for the selective reduction of NOx by a reducing agent such as NH3 or H2, advantageously formed by deposition in the form of a coating ("washcoat" according to English terminology) on a honeycomb structure mainly for mobile applications or a plate structure which is particularly found for stationary applications. The invention can also be formed in the form of extrudates or beads.

[0096] The honeycomb structure is formed of parallel channels open at both ends (flow-through in English) or has porous filtering walls and in this case the adjacent parallel channels are alternately blocked on either side of the channels in order to force the gas flow to pass through the wall (wall-flow monolith in English). Said honeycomb structure thus coated constitutes a catalytic bread. Said structure can be composed of cordierite, silicon carbide (SiC), aluminum titanate (AITi), alpha alumina, mullite or any other material whose porosity is between 30 and 70%. Said structure can be made of metal sheet, stainless steel containing chromium and aluminum, FeCrAI type steel.

[0097] The quantity of catalyst according to the invention deposited on said structure can be between 40 and 250 g / L for filter structures and between 60 and 300 g / L for structures with open channels.

[0098] The coating itself ("washcoat") comprises the catalyst according to the invention, advantageously combined with a binder such as ceria, zirconium oxide, alumina, non-zeolitic silica-alumina, titanium oxide, a mixed oxide of the ceria-zirconia type, a tungsten oxide, a spinel. Said coating is advantageously applied to said structure by a deposition method (washcoating in English) which consists of dipping the monolith in a suspension (slurry in English) of catalyst powder according to the invention in a solvent, preferably water, and potentially binders, metal oxides, stabilizers or other promoters. This dipping step can be repeated until the desired quantity of coating is reached. In certain cases the slurry can also be sprayed within the monolith. Once the coating is deposited, the monolith is calcined at a temperature of 300 to 600°C for 1 to 10 hours.

[0099] Said structure may be coated with one or more coatings. The coating comprising the catalyst according to the invention is advantageously associated with, i.e. covers one or is covered by, another coating having capacities for adsorbing pollutants, in particular NOx, for reducing pollutants, in particular NOx, or promoting the oxidation of pollutants, in particular that of ammonia.

[0100] Another possibility is to put the catalyst in extruded form. In this case, the resulting structure can contain up to 100% of the catalyst according to the invention.

[0101] Said structure coated with the catalyst according to the invention can advantageously be integrated into an exhaust line of an internal combustion engine operating mainly in a lean mixture, that is to say in excess air compared to the stoichiometry of the combustion reaction as is the case for Diesel engines or H2 combustion engines for example. Under these operating conditions of the Diesel engine, the exhaust gases contain in particular the following pollutants: soot, unburned hydrocarbons (HC), carbon monoxide (CO), nitrogen oxides (NOx). In the case of H2 combustion, the soot, HC and CO contents are very low because they come only from the lubricant, but nitrogen oxides are always present and the water content (H2O) is much higher than in the case of Diesel combustion.Upstream of said structure coated with the catalyst according to the invention, an oxidation catalyst may be placed whose function is to oxidize HC and CO as well as a filter to remove soot from the exhaust gases, the function of said coated structure being to remove NOx, its operating range being between 100 and 900°C and preferably between 150°C and 500°C.

[0102] Advantages of the invention

[0103] The catalyst according to the invention, based on an IZM-10 zeolite of AEI structural type and at least one transition metal, in particular copper, exhibits a significant gain in initiation compared to the catalysts of the prior art, such as catalysts based on zeolite of CHA or AEI structural type exchanged with copper. In particular, the use of the catalyst according to the invention makes it possible to obtain lower initiation temperatures for the NOx conversion reaction when the water content is high in the gases to be treated while ensuring very good selectivity for N2O.

[0104] EXAMPLES

[0105] The invention is illustrated by the following examples which are in no way limiting.

[0106] Example 1: preparation of (6R,10S)-6,10-dimethyl-5-azoniaspiro[4,5]decane in its hydroxide form (structuring R).

[0107] In a 500 mL two-necked flask containing 140 mL of water, 5.68 g (0.142 mol) of sodium hydroxide and 30.66 g (0.142 mol, 16.82 mL) of 1,4-dibromobutane are added with stirring. The mixture is heated to reflux and 16.07 g (0.142 mol, 19.13 mL) of (2R,6S)-2,6-dimethylpiperidine are added dropwise over half an hour using a dropping funnel. After twelve hours of reflux, the mixture is cooled to 0°C and 70 mL of cold 40% NaOH solution is added. The precipitate formed is extracted three times with 200 mL of chloroform. The extracted organic fractions are evaporated to a volume of 100 mL and the amine, in its bromide form, is precipitated with ether. The reaction yield is approximately 80-85%.

[0108] Molecular formula: CnH 22 NBr Molar mass: 248 g / mol

[0109] 1 H NMR (D2O, 400MHz, 25°C, 5 ppm) for (6R,10S)-6,10-dimethyl-5-azoniaspiro [4,5]decane (cis-trans mixture): 1.30 (d, 6H, CH3); 1.55 (m, 4H, CH2); 1.70 (m, 2H, CH2); 2.10 (m, 4H,CH2); 3.28 (t, 2H, CH2-N); 3.50 (t, 2H, CH2-N); 3.64 (m, 2H, CH-N).

[0110] 18.9 g of Ag2O (0.08 mol, 99%, Aldrich) are added to a 250 mL Teflon beaker containing 20 g of (6R,10S)-6,10-dimethyl-5-azoniaspiro[4,5]decane bromide (0.08 mol) and 100 mL of deionized water. The reaction medium is stirred away from light for 12 hours. The mixture is then filtered and part of the water is evaporated using a rotary evaporator. The filtrate obtained is composed of an aqueous solution of (6R,10S)-6,10-dimethyl-5-azoniaspiro[4,5]decane in its hydroxide form (29.06% by weight). The determination of this species is carried out by proton NMR using formic acid as a standard.

[0111] Example 2: preparation of an IZM-10 zeolite of AEI structural type according to the invention (with seeds).

[0112] 1.25 g of a zeolite of structural type FAU (CBV720, SiO2 / AI2C>3 = 33.34, Zeolyst, PAF = 14.34%, percentage of sodium in cationic form = 0.0045%) were mixed with 6.22 g of an aqueous solution of (6R,10S)-6,10-dimethyl-5-azoniaspiro[4,5]decane in its hydroxide form (29.06% by weight) prepared according to Example 1. 7.54 g of deionized water are added to the previous mixture, the preparation obtained is kept stirring for 10 minutes. In order to promote the formation of an IZM-10 zeolite of structural type AEI, 54 mg of seeds (5% relative to the mass of the CBV720 zeolite) of an IZM-10 zeolite of structural type AEI prepared according to Example 2 are added to the synthesis mixture and kept stirring for 5 minutes. The molar composition of the precursor gel is as follows: 1 SiO2: 0.03 AI2O3: 0.58 R: 40 H2O, i.e. a SiO2 / AI2O3 ratio of 33.3. The precursor gel is then transferred, after homogenization, into an autoclave.The autoclave is closed and then heated for 140 hours at 180°C with stirring at 35 rpm with a rotating spit system. The solid obtained is filtered, washed with deionized water and then dried overnight at 100°C. The loss on ignition of the dried solid is 10%. The solid is then introduced into a muffle furnace where a calcination step is carried out: the calcination cycle includes a temperature rise of 1.5°C / min up to 200°C, a hold at 200°C maintained for 2 hours, a temperature rise of 1°C / min up to 550°C followed by a hold at 550°C maintained for 8 hours and then a return to room temperature.

[0113] The calcined solid product was analyzed by X-ray diffraction and identified as consisting of an IZM-10 zeolite of structural type AEI with a purity greater than 99% by weight. X-ray fluorescence analysis gives a molar ratio of SiO2 / AI2O3 = 29.20 and a molar ratio of AI2O3 / Na2O = 460. Ion exchange with Cu

[0114] 1g of calcined IZM-10 zeolite is suspended in 30 mL of a solution of [Cu(NH3)4](NO3)20.016 M for 1 day with stirring at room temperature. The final solid is separated, washed and dried and calcined under dry air flow at 550°C for 8 hours.

[0115] Chemical analysis by X-ray fluorescence (FX) gave a SiC^ / AhOs molar ratio of 29.20 and a mass percentage of Cu of 2.78%.

[0116] The resulting catalyst is designated CulZM-10.

[0117] Example 3 (comparative): preparation of a Cu-CHA catalyst based on a commercial zeolite

[0118] 1g of commercial CHA type zeolite is suspended in 30 mL of a 0.016 M [CU(NH3)4](NO3)2 solution for 1 day with stirring at room temperature. The final solid is separated, washed and dried and calcined under a flow of dry air at 550°C for 8 hours.

[0119] Chemical analysis by X-ray fluorescence (FX) gives a SiC^ / AhOs molar ratio of 17.8 and a mass percentage of Cu of 2.92%.

[0120] The catalyst obtained is noted CuCHA.

[0121] Example 4 (comparative): preparation of a Cu-AEI catalyst based on a commercial zeolite

[0122] 1g of commercial AEI type zeolite is suspended in 30 mL of a 0.016 M [CU(NH3)4](NO3)2 solution for 1 day with stirring at room temperature. The final solid is separated, washed and dried and calcined under a flow of dry air at 550°C for 8 hours.

[0123] Chemical analysis by X-ray fluorescence (FX) gives a SiC^ / AhOs molar ratio of 19.2 and a mass percentage of Cu of 2.85%.

[0124] The catalyst obtained is noted CuAEI.

[0125] Example 5: Conversion of NOx: comparison of copper catalysts according to the invention with the prior art

[0126] A catalytic test for the reduction of nitrogen oxides (NOx) by ammonia (NH3) in the presence of oxygen (O2) under Standard SCR conditions is carried out at different operating temperatures for the catalysts prepared according to Example 2 (CulZM-10), Example 3 (CuCHA) and Example 4 (CuAEI).

[0127] For the testing of each sample, 200 mg of catalyst in powder form is placed in a quartz reactor. 145 L / h of a representative feed of an exhaust gas mixture from an H2 engine is fed into the reactor. This feed has the following molar composition: 450 ppm NO, 150 ppm NO2, 660 ppm NH3, 15% O2, 15% H2O, qpc N2.

[0128] An FTIR analyzer can measure the concentration of NO, NO2, NH3, N2O, CO, CO2, H2O, O2 species at the reactor outlet. NOx conversions are calculated as follows:

[0129] Conversion = (NOx in -NOx out) / NOx in

[0130] The NOx conversion results are shown in Figure 2, the curves marked by triangles, circles and squares corresponding respectively to the tests carried out with the catalysts synthesized according to Example 2 (CulZM-10), Example 3 (CuCHA) and Example 4 (CuAEI). The catalyst according to the invention offers an optimized initiation temperature and therefore makes it possible to convert NOx at a lower temperature than the catalyst synthesized according to the prior art.

[0131] The CulZM-10 catalyst synthesized according to the invention is particularly effective at low temperatures with 53% NOx conversion at 190°C while the CuAEI and CuCHA catalysts only offer 35% and 28% NOx conversion at this same temperature.

[0132] The ignition temperatures of catalysts containing 3% copper are given in Table 2 below for Standard-SCR conditions:

[0133] Table 2

[0134] T50 corresponds to the temperature at which 50% of the NOx in the gas mixture is converted by the catalyst. T80 corresponds to the temperature at which 80% of the NOx in the gas mixture is converted by the catalyst. T90 corresponds to the temperature at which 90% of the NOx in the gas mixture is converted by the catalyst.

[0135] The CulZM-10 catalyst synthesized according to the invention gives superior performances to the CuAEI and CuCHA catalysts synthesized according to the prior art in terms of initiation temperatures and NOx conversion at low temperatures (T<300°C) in Standard SCR conditions. Indeed, at the same conversion rate (50% or 80%), the initiation temperatures obtained with the catalyst according to the invention CulZM-10 are lower compared to those obtained with the CuAEI and CuCHA catalysts. The maximum nitrogen protoxide (N2O) emissions are given in the following table 3:

[0136] Table 3

[0137] The CulZM-10 catalyst synthesized according to the invention gives lower N2O emissions than the CuAEI and CuCHA catalysts synthesized according to the prior art.

[0138] The following examples according to the invention relate to Fe-IZM-10 zeolites of AEI structural type, therefore here zeolites with ion exchange with iron and not with copper like the previous examples.

[0139] Example 6: preparation of a Fe-IZM-10 zeolite of structural type AEI according to the invention (with seeds).

[0140] 1.25 g of a zeolite of structural type FAU (CBV720, SiC^ / AhCh = 33.34, Zeolyst, PAF = 14.34%, percentage of sodium in cationic form = 0.0045%) were mixed with 6.22 g of an aqueous solution of (6R,10S)-6,10-dimethyl-5-azoniaspiro[4,5]decane in its hydroxide form (29.06% by weight) prepared according to Example 1. 7.54 g of deionized water are added to the previous mixture, the preparation obtained is kept stirring for 10 minutes. In order to promote the formation of an IZM-10 zeolite of AEI structural type, 54 mg of seeds (5% relative to the mass of the CBV720 zeolite) of an IZM-10 zeolite of AEI structural type prepared according to Example 2 are added to the synthesis mixture and kept stirring for 5 minutes. The molar composition of the precursor gel is as follows: 1 SiC>2: 0.03 AI2O3: 0.58 R: 40 H2O, i.e. a SiC^ / AhCh ratio of 33.3. The precursor gel is then transferred, after homogenization, into an autoclave.The autoclave is closed and then heated for 140 hours at 180°C with stirring at 35 rpm with a rotating spit system. The solid obtained is filtered, washed with deionized water and then dried overnight at 100°C. The loss on ignition of the dried solid is 10%. The solid is then introduced into a muffle furnace where a calcination step is carried out: the calcination cycle includes a temperature rise of 1.5°C / min up to 200°C, a hold at 200°C maintained for 2 hours, a temperature rise of rC / min up to 550°C followed by a hold at 550°C maintained for 8 hours and then a return to room temperature. The calcined solid product was analyzed by X-ray diffraction and identified as consisting of an IZM-10 zeolite of AEI structural type with a purity greater than 99% by weight. X-ray fluorescence analysis gives a molar ratio SiO2 / AI2O3 = 29.20 and a molar ratio AI2O3 / Na2O = 460.

[0141] Ionic exchange with Fe

[0142] 1g of calcined IZM-10 zeolite is suspended in 200mL of a solution of Fe(NOa)3 (1.5*10 -4 molar) for 16 hours with stirring at 80°C. The final solid is separated, washed and dried for 12 hours at a temperature of 100°C and calcined under dry air flow at 550°C for 8 hours.

[0143] Chemical analysis by X-ray fluorescence (FX) gave a SiO2 / AI2C>3 molar ratio of 29.20 and a mass percentage of Fe of 2.06%.

[0144] The resulting catalyst is designated FelZM-10.

[0145] Example 7 (comparative): preparation of an Fe-AEI catalyst based on a commercial zeolite

[0146] 1g of commercial AEI type zeolite is suspended in 200 mL of a Fe(NOs)3 solution (1.5*10' 4 molar) for 16 hours with stirring at 80°C. The final solid is separated, washed and dried for 12 hours at a temperature of 100°C and calcined under dry air flow at 550°C for 8 hours.

[0147] Chemical analysis by X-ray fluorescence (FX) gives a SiO2 / AI2C>3 molar ratio of 19.2 and a mass percentage of Fe of 2.28%.

[0148] The catalyst obtained is noted FeAEI.

[0149] Example 8: Conversion of NOx: comparison of iron catalysts according to the invention with the prior art

[0150] A catalytic test for the reduction of nitrogen oxides (NOx) by ammonia (NH3) in the presence of oxygen (O2) under Standard SCR conditions is carried out at different operating temperatures for the catalysts prepared according to Example 6 (FelZM-10) and Example 7 (FeAEI).

[0151] For testing each sample, 200 mg of catalyst in powder form is placed in a quartz reactor. 145 L / h of a representative charge of an H2 engine exhaust gas mixture is fed into the reactor.

[0152] This feedstock has the following molar composition: 450 ppm NO, 150 ppm NO2, 660 ppm NH3, 15% O2, 15% H2O, qpc N2. An FTIR analyzer is used to measure the concentration of NO, NO2, NH3, N2O, CO, CO2, H2O, O2 species at the reactor outlet. The NOx conversions are calculated as follows:

[0153] Conversion = (NOx in -NOx out) / NOx in

[0154] The NOx conversion results are shown in Figure 3, the curves marked by squares and crosses corresponding respectively to the tests carried out with the catalysts synthesized according to Example 6 (FelZM-10) and Example 7 (FeAEI).

[0155] The catalyst according to the invention offers an optimized initiation temperature and therefore makes it possible to convert NOx at a lower temperature than the catalyst synthesized according to the prior art.

[0156] The FelZM-10 catalyst synthesized according to the invention is particularly effective at low temperatures with 45% NOx conversion at 250°C while the FeAEI catalyst only offers 32% NOx conversion at this same temperature.

[0157] The FelZM-10 catalyst synthesized according to the invention gives superior performances to the FeAEI catalyst synthesized according to the prior art in terms of initiation temperatures and NOx conversion in Standard SCR conditions.< / fau>

Claims

CLAIMS 1. Process for the preparation of a catalyst based on a zeolite, called IZM-10, of structural type AEI and at least one transition metal comprising at least the following steps: i) mixing in an aqueous medium, a zeolite of structural type FAU having a molar ratio SIO2 (FAU) / AI2O3 (FAU) of between 10 and 60, limits included and a mass percentage of sodium in cationic form of less than 0.005%, of an organic nitrogen compound R, R being (6R,10S)-6,10-dimethyl-5-azoniaspiro[4,5]decane in its hydroxide form and optionally sodium hydroxide, the reaction mixture having the following molar composition: -(SiC>2 (FAU)) / (AhO3 ( AU)) corn taken between 10 and 60, preferably between 30 and 50 -H2O / (SiC>2 (AU)) between 20 and 60, preferably between 30 and 50 -R / (SiO2 (FAU)) between 0.05 and 0.70, preferably between 0.15 and 0.60 -Na2O (NaOH) / (SiC>2 (AU)) between 0 and 0.20, preferably between 0 and 0.15 -Na2O (AU) / (SiC>2 (AU)) between 3.5*10 -5 and 7*10 -5 , preferably between 4*10 -5 and 6*10' 5in which Na2O (FAU) denotes the quantity of Na2O provided by the FAU zeolite, Na2O (NaOH) denotes the quantity of Na2O provided by the soda, SiC>2 (FAU) denotes the quantity of SiC>2 provided by the FAU zeolite, and AhO3 (FAU) denotes the quantity of AI2O3 provided by the FAU zeolite, until a homogeneous precursor gel is obtained; ii) the hydrothermal treatment of said precursor gel obtained at the end of step i) at a temperature of between 120°C and 220°C, for a period of between 12 hours and 7 days until an AEI zeolite is obtained; iii) at least one ion exchange comprising bringing said zeolite obtained at the end of the previous step into contact with a solution comprising at least one species capable of releasing a transition metal, in solution in reactive form with stirring at room temperature for a period of between 1 hour and 2 days;iv) a heat treatment by drying the solid obtained at the end of the previous step at a temperature between 20 and 150°C followed by at least one calcination under air flow at a temperature between 400 and 700°C for a duration between 8 and 24 hours.; 2. Preparation process according to claim 1 in which steps iii) and iv) are repeated.

3. Preparation process according to one of claims 1 or 2 wherein said transition metal released in the exchange solution of step iii) is selected from the group formed by the following elements: Ti, V, Mn, Mo, Fe, Co, Cu, Cr, Zn, Nb, Ce, Zr, Rh, Pd, Pt, Au, W, Ag, preferably from the group formed by the following elements: Fe, Cu, Nb, Ce or Mn, more preferably from Fe, Ce or Cu, alone or in a mixture and even more preferably said transition metal is Cu or Fe.

4. Process for preparing a catalyst according to one of claims 1 to 3 in which the SiC^ / AhCh molar ratio of the AEI zeolite is between 10 and 60, preferably between 12 and 50, limits included and the AhO3 / Na2O molar ratio of the AEI zeolite is greater than 100 and preferably greater than 400.

5. Process for preparing a catalyst according to one of claims 1 to 4 in which the zeolite of structural type FAU has a molar ratio SiC^ / AhCh of between 20 and 50, limits included, and a mass percentage of Na2O of less than 0.0048%.

6. Process for preparing a catalyst according to one of claims 1 to 5 in which no sodium hydroxide is added to the reaction mixture of step i) (Na2O(NaOH) / (SiC>2 <fau>) = 0).

7. Process for preparing a catalyst according to one of the preceding claims, in which crystalline seeds of a zeolite of structural type AEI are added to the reaction mixture of step i), preferably in an amount of between 0.01 and 10% by weight relative to the total mass of the sources of tetravalent and trivalent elements in anhydrous form present in said mixture, said crystalline seeds not being taken into account in the total mass of the sources of SiC>2 and AI2O3.

8. Process for preparing a catalyst according to one of the preceding claims in which step i) comprises a step of maturing the reaction mixture at a temperature of between 20 and 100°C, with or without stirring, for a period of between 30 minutes and 48 hours.

9. Process for preparing a catalyst according to one of the preceding claims, in which the hydrothermal treatment of step ii) is carried out under autogenous pressure at a temperature between 120°C and 220°C, preferably between 150°C and 200°C, even more preferably between 160°C and 195°C, for a period of between 12 hours and 7 days, preferably between 12 hours and 6 days.

10. Process for preparing a catalyst according to one of the preceding claims, in which the solid phase obtained at the end of step ii) is filtered, washed, and dried at a temperature of between 20 and 150°C, preferably between 60 and 100°C, for a period of between 5 and 24 hours to obtain a dried zeolite.

11. Process for preparing a catalyst according to claim 10 in which the dried zeolite is then calcined at a temperature of between 450 and 700°C for a period of between 2 and 20 hours, the calcination possibly being preceded by a gradual increase in temperature.

12. Process for preparing a catalyst according to one of the preceding claims in which the content of transition metal(s) introduced by the ion exchange step iii) is between 0.5 and 6% by mass, preferably between 0.5 and 5% by mass, more preferably between 1 and 4% by mass, relative to the total mass of the final anhydrous catalyst.

13. Catalyst for the selective reduction of NOx comprising a zeolite of structural type AEI with a molar ratio SiO2 / AI2C>3 of between 10 and 60, limits included, and of purity greater than or equal to 98% by weight, preferably greater than or equal to 99% by weight; and 0.5 to 6% of a transition metal, preferably copper or iron, and in particular obtained by the preparation process according to one of claims 1 to 12.

14. Process for the selective reduction of NO X by a reducing agent such as NH3 or H2 using the catalyst directly obtained by the preparation process according to one of claims 1 to 12 for the selective reduction of NO X by a reducing agent such as NH3 or H2.

15. Process for the selective reduction of NO X by a reducing agent such as NH3 or H2 according to claim 14 wherein the catalyst is formed by deposition in the form of a coating, on a honeycomb structure or a plate structure, or said catalyst is in the form of an extrudate or a bead, containing up to 100% of said catalyst.

16. Process for the selective reduction of NO X by a reducer such as NH3 or H2 according to claim 15 in which the honeycomb structure is formed of parallel channels open at both ends or comprises porous filtering walls for which the adjacent parallel channels are alternately blocked on either side of the channels.

17. Process for the selective reduction of NO X by a reducer such as NH3 or H2 according to one of claims 15 or 16 in which the quantity of catalyst deposited on said structure is between 40 and 250 g / L for filter structures and between 60 and 300 g / L for structures with open channels.

18. Process for the selective reduction of NO X by a reducing agent such as NH3 or H2 according to one of claims 15 to 17 in which the catalyst is associated with a binder such as ceria, zirconium oxide, alumina, non-zeolitic silica-alumina, titanium oxide, a mixed oxide of ceria-zirconia type, a tungsten oxide and / or a spinel for be shaped by deposition in the form of a coating, said coating preferably being able to be associated with another coating having capacities for adsorbing pollutants, in particular NOx, for reducing pollutants, in particular NOx, or promoting the oxidation of pollutants.

19. Process for the selective reduction of NO X by a reducing agent such as NH3 or H2 according to one of claims 14 to 18 in which said catalyst is integrated: - in an exhaust line of an internal combustion engine operating on carbonaceous or non-carbonaceous fuels, or - in a reactor to treat industrial fumes.< / fau>

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