FR3081344A1 - PROCESS FOR THE SYNTHESIS OF AN AFX STRUCTURAL TYPE ZEOLITE FROM A MIXTURE OF ZEOLITES IN THE PRESENCE OF AN ORGANIC NITROGEN STRUCTURANT - Google Patents

Abstract

The invention relates to a process for the preparation of an AFX structural zeolite comprising at least the following steps: i) the mixing in an aqueous medium of at least two zeolites of structural type FAU, each of said zeolites of structural type FAU having an SiO2 / Al2O3 molar ratio of between 2 and 200, limits included, and a Pze parameter of less than 3250, of a nitrogenous organic compound R, of at least one source of at least one alkali metal and / or alkaline earth metal M, the reaction mixture having the following molar composition: (SiO 2 (FAU)) / (Al 2 O 3 (FAU)) between 2 and 32, H 2 O / (SiO 2 (FAU)) between 1 and 100, R / (SiO 2 (FAU) )) between 0.01 to 0.6, M2 / nO / (SiO2 (FAU)) between 0.005 to 0.45, limits included, to obtain a homogeneous precursor gel; ii) the hydrothermal treatment of said precursor gel obtained at the end of step i).

Description

Technical area

The present invention relates to a new process for the preparation of an AFX structural type zeolite. This new process allows the synthesis of an AFX structural type zeolite by conversion / transformation under hydrothermal conditions of a mixture of at least two zeolites of FAU structural type. In particular, said new process makes it possible to carry out the synthesis of a zeolite of structural type AFX, from a mixture of at least two zeolites of structural type FAU used as source of silicon and aluminum and of a molecule organic or specific structuring agent comprising two quaternary ammonium functions, chosen from 1,5-bis (methylpiperidinium) pentane, 1,6-bis (methylpiperidinium) hexane or 1,7-bis (methylpiperidinium) heptane in its dihydroxide form. Said AFX structural type zeolite obtained according to the process of the invention advantageously finds its application as a catalyst, adsorbent or separation agent.

Prior art

Microporous crystallized materials, such as zeolites or silicoaluminophosphates, are solids widely used in the petroleum industry as a catalyst, catalyst support, adsorbent or separation agent. Although many microporous crystal structures have been discovered, the refining and petrochemical industry is always looking for new zeolitic structures which have particular properties for applications such as purification or separation of gases, conversion of carbonaceous or other species.

The AFX structural type zeolites include in particular the SSZ-16 zeolite, and the SAPO-56 and MEAPSO-56 zeotypes. The AFX structural type zeolite has a three-dimensional pore system delimited by eight tetrahedra and is formed by two types of cages: gmelinite (GME cage) and a large AFT cage (~ 8.3 x 13.0 A). Many methods for synthesizing zeolites of the AFX structural type, in particular the SSZ-16 zeolite, are known. The SSZ-16 zeolite was synthesized using nitrogenous organic species derived from 1,4-di (1-azoniabicyclo [2.2.2] octane) lower alkane compounds (US Patent No. 4,508,837). Chevron Research and Technology Company prepared the zeolite SSZ-16 in the presence of DABCO-C _n -diquat cations, where DABCO represents 1,4-diazabicyclo [2.2.2] octane and n is 3, 4 or 5 (US Patent No .5,194,235). SB Hong et al used the diquaternary alkylammonium ion Et6-diquat-n, where Et6-diquat represents Ν ', Ν'-bis-triethylpentanediammonium and n is 5, as structuring agents for the synthesis of the zeolite SSZ-16 (Micropor Mesopor. Mat., 60 (2003) 237-249). We can also cite the use of cations

1.3- bis (adamantyl) imidazolium as structuring agent for the preparation of zeolite of AFX structural type (R. H. Archer et al. In Microp. Mesopor. Mat., 130 (2010) 255-2265; Johnson Matthey Company W02016077667A1). Inagaki Satoshi et al. (JP2016169139A) used divalent cations Ν, Ν, Ν ', Ν'-tétraarquirubicyclo [2.2.2] oct-7-ene-2,3: 05,6-dipyrrolidium substituted with alkyl groups to prepare the zeolite SSZ- 16. Chevron USA (WO2017 / 200607 A1) proposes to carry out the synthesis of an SSZ-16 zeolite using the dications: 1,1 '- (1,4cyclohexylenedimethylene) bis [1 -methylpiperidinium], 1, 1' - (1, 4cyclohexylenedimethylene) bis [1-methylpyrrolidinium], 1, T- (1,4-cyclohexylenedimethylene) bis [1-ethylpyrrolidinium]. H.-Y. Chen et al. (Johnson Matthey Company, US2018 / 0093897) used a mixture of cations containing at least 1,3-bis (adamantyl) imidazolium and a neutral amine to prepare the JMZ-10 zeolite of structural type AFX in the absence of alkaline cations. H.-Y. Chen et al. (Johnson Matthey Company, US2018 / 0093259) used a mixture of cations containing an organic molecule chosen from

1.3- bis (adamantyl) imidazolium, N, N-dimethyl-3,5-dimethylpipendinium, N, Ndiethyl-cis 2,6-dimethylpiperidinium, Ν, Ν, Ν-1-tnmethyladamantylammonium, Ν, Ν, Ν -dimethylethylcyclohexylammonium and at least one alkaline earth metal cation to obtain the JMZ-7 zeolite of AFX structural type which has Al sites close to the zeolite obtained by a synthesis containing alkali cations.

Description of the invention

Summary of the invention

The invention relates to a process for the preparation of an AFX structural type zeolite comprising at least the following steps:

i) the mixture in aqueous medium, of at least two zeolites of structural type FAU, each of said zeolites of structural type FAU having a molar ratio S1O2 / AI2O3 between 2 and 200, limits included, and a parameter P _ze , corresponding to the respective percentage (expressed in%) of each of said FAU zeolites in anhydrous form relative to all of the FAU zeolites in anhydrous form multiplied by the SiO2 / AI ₂ O ₃ molar ratio of each of said FAU zeolites, preferably less than 3250 less than 3150, of an organic nitrogen compound R, R being chosen from 1,5-bis dihydroxide (methylpiperidinium) pentane, 1,6-bis dihydroxide (methylpiperidinium) hexane or dihydroxide

1,7-bis (methylpiperidinium) heptane, from at least one source of at least one alkali and / or alkaline-earth metal M of valence η, n being an integer greater than or equal to 1, chosen from lithium, the potassium, sodium, magnesium and calcium and the mixture of at least two of these metals, the reaction mixture having the following molar composition: (SiO ₂ (fau)) / (AI ₂ O ₃ (fau)) between 2 and 32, preferably between 3 and 30 H ₂ O / (SîO ₂ (fau)) between 1 and 100, preferably between 5 and 60 R / (SîO ₂ (fau)) between 0.01 and 0, 6, preferably between 0.05 and 0.5 M _{2 / n} O / (SiO ₂ (fau)) between 0.005 to 0.45, preferably between 0.05 and 0.25, limits included, in which SiO ₂ <fau) is the amount of SiO ₂ provided by said at least two FAU zeolites, and AI ₂ O ₃ (fau) is the amount of AI ₂ O ₃ provided by said at least two FAU zeolites, until obtaining a homogeneous precursor gel;

ii) the hydrothermal treatment of said precursor gel obtained at the end of step i) at a temperature between 120 ° C and 220 ° C, for a period of between 12 hours and 15 days.

Preferably, R is 1,6-bis (methylpipendinium) hexane dihydroxide.

Advantageously, the SiO ₂ / AI ₂ O ₃ ratio of the AFX zeolite obtained is between 4 and 100, preferably between 6 and 80, limits included.

Preferably, M is sodium.

Preferably, the source of at least one alkali and / or alkaline earth metal M is sodium hydroxide.

Preferably, each of said zeolites of structural type FAU has a S1O2 / AI2O3 molar ratio of between 3 and 100, limits included.

It is possible to add crystalline seeds of a zeolite of AFX structural type to the reaction mixture of step i), preferably in an amount of between 0.01 and 10% by weight relative to the total weight of the sources of SiO ₂ and of AI ₂ O ₃ in anhydrous form present in said mixture, said crystalline seeds not being taken into account in the total mass of the sources of SiO ₂ and of AI ₂ O ₃ .

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

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 195 ° C, for a period between 12 hours and 15 days, preferably between 12 hours and 12 days, very preferably between 12 hours and 8 days.

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 time between 5 and 24 hours to obtain a dried zeolite.

The dried zeolite can then be calcined at a temperature between 450 and 700 ° C for a period between 2 and 20 hours, the calcination may be preceded by a gradual rise in temperature.

The invention also relates to a zeolite of the AFX structural type with an S1O2 / AI2O3 ratio of between 4 and 100, limits included, capable of being obtained by the preparation process previously described.

The invention also relates to a zeolite of the AFX structural type with a ratio of S1O2 / AI2O3 of between 4 and 100, limits included, capable of being obtained by the preparation process previously described and calcined, for which the mean values of d _hk | and relative intensities measured on an X-ray diffraction diagram are as follows:

2 theta (°) dhkl (Â) Irel 2 theta (°) dhkl (Â) Irel 7.53 11,73 ff 26.16 3.40 mf 8.78 10.07 F 26.99 3.29 ff 11.75 7.52 FF 27.25 3.27 ff 13,02 6.79 m 27.62 3.23 ff 15.04 5.89 ff 28.26 3.16 m 15.70 5.64 f 28.74 3.10 ff 17.55 5.05 f 30.29 2.95 mf 18.07 4.91 m 30.63 2.92 m 19.59 4.53 ff 31.22 2.87 ff 19,91 4.46 f 31.65 2.82 mf 20.43 4.34 F 31.94 2.80 ff 21.89 4.06 FF 32.76 2.73 ff 22.32 3.98 ff 33.92 2.64 mf 22.61 3.93 ff 34.31 2.61 ff 23,00 3.86 ff 34.82 2.57 f 23.56 3.77 ff 35.38 2.54 ff 23.86 3.7 ff 35.85 2.50 ff 24,10 3.69 ff 37.47 2.40 ff

where FF = very strong; F = strong; m = medium; mf = medium weak; f = weak; ff = very low, the relative intensity l _re i being given in relation to a relative intensity scale where a value of 100 is assigned to the most intense line of the X-ray diffraction diagram: ff <15; 15 <f <30; 30 <mf <50; 50 <m <65; 65 <F <85;FF> 85.

List of Figures

Figure 1 shows the chemical formulas of organic nitrogen compounds which can be chosen as a structuring agent used in the synthesis process according to the invention.

FIG. 2 represents the X-ray diffraction diagram of the AFX zeolite obtained according to Example 4.

FIG. 3 represents a scanning electron microscope (SEM) of the AFX zeolite obtained according to example 5.

Other characteristics and advantages of the method of synthesis according to the invention will appear on reading the description below of nonlimiting examples of embodiments, with reference to the appended figures and described below.

Detailed description of the invention

Unless otherwise indicated, the ranges of values presented below are understood to include limits.

The present invention relates to a new process for the preparation of a zeolite of the AFX structural type, by conversion / transformation under hydrothermal conditions of a mixture of two zeolites of the FAU structural type, in the presence of a specific nitrogenous or structuring organic compound. chosen from the following compounds: 1,5-bis (methylpiperidinium) pentane, 1,6-bis (methylpiperidinium) hexane or

1,7-bis (methylpiperidinium) heptane, in dihydroxide form.

In particular, the applicant has discovered that the nitrogenous or structuring organic compound chosen from 1,5-bis (methylpiperidinium) pentane,

1,6-bis (methylpiperidinium) hexane or 1,7-bis (methylpiperidinium) heptane in its dihydroxide form, mixed with at least two zeolites of structural type FAU having a molar ratio SiO ₂ / AI ₂ O ₃ between 2 and 200, the mass percentages of each of the zeolites and the SiO ₂ / AI ₂ O ₃ ratios of each of the zeolites used as the source of silicon and of aluminum meeting a condition such as the mathematical product, P _ze , between the mass percentage of each FAU zeolite in its anhydrous form (expressed in%) used in the mixture of starting FAU zeolites and its SiO ₂ / AI ₂ O ₃ molar ratio is less than 3250, preferably less than 3150, leads to the production of a gel precursor of an AFX structural type zeolite having a molar ratio of the total amount of SiO ₂ to the total amount of AI ₂ O ₃ between 2 and 32, then to the production of a zeolite of pure AFX structural type. Any other crystallized or amorphous phase is generally and very preferably absent from the crystallized solid consisting of the zeolite of AFX structural type obtained at the end of the preparation process. The zeolite obtained according to the present invention may comprise at least 90%, very preferably at least 95%, more preferably at least 98% and even more preferably at least 99.8% of a zeolite of structural type AFX pure.

More precisely, a parameter P _ze is defined for each of the FAU zeolites present in the mixture of starting FAU zeolites, the sum of the percentages of each of the FAU zeolites in the anhydrous form in the starting mixture being equal to 100. For example, when starting from a mixture of two FAU zeolites, said parameter P _ze for the first FAU zeolite corresponds to the percentage (expressed in%) of said first FAU zeolite in its anhydrous form in the mixture of starting FAU zeolites multiplied by the SiO ₂ / AI ₂ O ₃ molar ratio of said first FAU zeolite, and said parameter P _ze for the second FAU zeolite corresponds to the percentage (expressed in%, complement to 100 of the percentage of the first FAU zeolite) of said second FAU zeolite its anhydrous form in the mixture of starting FAU zeolites multiplied by the molar ratio S1O2 / AI2O3 of said second FAU zeolite.

The present invention more specifically relates to a new process for preparing a zeolite of AFX structural type comprising at least the following steps:

i) the mixture in aqueous medium, of at least two zeolites of structural type FAU, each of said zeolites having a molar ratio S1O2 / AI2O3 of between 2 and 200, and a parameter P _ze corresponding to the respective percentage (expressed in%) of each of said FAU zeolites in the anhydrous form in the mixture of starting FAU zeolites multiplied by the molar ratio S1O2 / AI2O3 of each of said zeolites, less than 3250, preferably less than 3150, of an organic nitrogen compound R, also called structuring , specific, chosen from dihydroxide

1.5- bis (methylpiperidinium) pentane, dihydroxide

1.6- bis (methylpiperidinium) hexane, or dihydroxide

1.7- bis (methylpiperidinium) heptane, at least one alkali metal and / or one alkaline earth metal M of valence η, n being an integer greater than or equal to 1, the mixture having the following molar composition:

(S1O2 (fau)) / (AI ₂ O3 (fau)) between 2 and 32, preferably between 3 and 30 H ₂ O / (SîO2 (fau)) between 1 and 100, preferably between 5 and 60 R / (SiO _{2 (} FAU)) between 0.01 to 0.6, preferably between 0.05 and 0.5 M ₂ / nO / (SiO ₂ (fau)) between 0.005 to 0.45, preferably between 0.05 and 0.25, limits included, in which SiO ₂ (fau) is the amount of SiO ₂ provided by the two zeolites of structural type FAU, and AI2O3 (fau) is the amount of AI2O3 provided by the two zeolites of structural type FAU, H ₂ O the molar quantity of water present in the reaction mixture, R the molar quantity of said nitrogenous organic compound, M ₂ / nO the molar quantity expressed in oxide form of M ₂ / nO by the metal source alkaline and / or alkaline earth metal, and M is one or more alkali and / or alkaline earth metal (s) chosen from lithium, sodium, potassium, calcium, magnesium and the mixture of at least two of these met aux, very preferably M is sodium, step i) being carried out for a period allowing a homogeneous mixture called a precursor gel to be obtained;

ii) 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 15 days, until said zeolite AFX structural type is formed.

An advantage of the present invention is therefore to provide a new preparation process allowing the formation of a high purity AFX structural type zeolite from a mixture of at least two zeolites of FAU structural type, said process being used in the presence of a specific organic structuring agent chosen from 1,5-bis (methylpiperidinium) pentane dihydroxide, dihydroxide

1.6- bis (methylpiperidinium) hexane or dihydroxide

1.7- bis (methylpiperidinium) heptane.

Another advantage of the present invention is to allow the preparation of a precursor gel of a zeolite of AFX structural type having a molar ratio S1O2 / AI2O3 comprised between the molar ratios S1O2 / AI2O3 of zeolites of structural type FAU at the start.

The starting FAU structural type zeolites having an S1O2 / AI2O3 molar ratio of between 2 and 200, limits included, can be obtained by any method known by a person skilled in the art, for example by direct synthesis in the case of FAU zeolites having a S1O2 / AI2O3 molar ratio less than 6 or by treatment with steam (steaming) and acid washings on a zeolite of FAU structural type in the case of FAU zeolites having a S1O2 / AI2O3 molar ratio greater than 6. Said zeolites of structural type FAU having a molar ratio S1O2 / AI2O3 of between 2 and 200 can be used in their sodium form or any other form or after partial or total exchange of sodium cations with ammonium cations followed or not by a calcination step . We can cite, among the sources of FAU with an S1O2 / AI2O3 ratio between 2 and 200, the commercial zeolites CBV100, CBV600, CBV712, CBV720, CBV760 and CBV780 produced by Zeolyst, the commercial zeolites HSZ-320HOA, HSZ-350HUA, HSZ-360HUA and HSZ-385HUA produced by TOSOH.

The preparation process according to the invention therefore makes it possible to adjust the S1O2 / AI2O3 ratio of the precursor gel as a function of the respective supply of S1O2 and AI2O3 in each of said zeolites of structural type FAU within the reaction mixture.

Step i) comprises the mixing, in an aqueous medium, of at least two zeolites of structural type FAU, each of said zeolites FAU having a molar ratio S1O2 / AI2O3 of between 2 and 200, limits included, and a parameter P _ze corresponding to the respective percentage (expressed in%) of each of said FAU zeolites in the mixture of starting FAU zeolites multiplied by the molar ratio S1O2 / AI2O3 of each of said zeolites, less than 3250, preferably less than 3150, of a

organic nitrogen compound R, R being dihydroxide of 1,5-bis (methylpiperidinium) pentane, the dihydroxide of 1,6-bis (methylpiperidinium) hexane, or the dihydroxide of 1,7-bis (methylpiperidinium) heptane, at least a metal alkaline and / or a metal

alkaline earth M of valence η, n being an integer greater than or equal to 1, the reaction mixture having the following molar composition:

(SiO ₂ (fau)) / (AI ₂ O ₃ (fau)) between 2 and 32, preferably between 3 and 30

H ₂ O / (SîO2 (fau)) between 1 and 100, preferably between 5 and 60

R / (SiO _{2 (} FAU)) between 0.01 to 0.6, preferably between 0.05 and 0.5

M ₂ / nO / (SiO ₂ (fau)) between 0.005 to 0.45, preferably between 0.05 and 0.25, limits included, in which S1O2 (fau) is the quantity of S1O2 supplied by said at least two FAU zeolites, and AI2O3 <fau) is the quantity of AI2O3 provided by said at least two FAU zeolites, H ₂ O is the molar quantity of water present in the reaction mixture, R is the molar quantity of said nitrogenous organic compound, M ₂ / _n O the molar quantity expressed in oxide form of M ₂ / nO by the source of alkali metal and / or alkaline earth metal, and M is one or more alkali metal (s) and / or alkaline- earthy chosen from lithium, sodium, potassium, calcium, magnesium and the mixture of at least two of these metals, very preferably M is sodium.

Step i) makes it possible to obtain a homogeneous precursor gel.

Step ii) comprises a hydrothermal treatment of said precursor gel obtained at the end of step i) which is carried out at a temperature between 120 ° C and 220 ° C for a period between 12 hours and 15 days, up to 'said AFE structural type zeolite crystallize.

According to the invention, at least two zeolites of structural type FAU having a molar ratio S1O2 / AI2O3 of between 2 and 200, and preferably between 3 and 100, are incorporated into the reaction mixture for the implementation of l step (i) as sources of silicon and aluminum element.

According to the invention, R is a nitrogenous organic compound chosen from 1,5-bis (methylpiperidinium) pentane dihydroxide, dihydroxide

1.6- bis (methylpiperidinium) hexane or dihydroxide

1.7- bis (methylpiperidinium) heptane, said compound being incorporated in the reaction mixture for the implementation of step (i), as an organic structuring agent. The anion associated with the quaternary ammonium cations present in the structuring organic species for the synthesis of a zeolite of AFX structural type according to the invention is the hydroxide anion.

According to the invention, at least one source of at least one alkali and / or alkaline-earth metal M of valence n, is used in the reaction mixture of step i), n being an integer greater than or equal at 1, M being preferably chosen from lithium, potassium, sodium, magnesium and calcium and the mixture of at least two of these metals. Most preferably, M is sodium.

Preferably, the source of at least one alkali and / or alkaline earth metal M is sodium hydroxide.

According to the invention, at least two zeolites of structural type FAU with different molar ratios S1O2 / AI2O3, each respecting a condition such that: P _ze is less than 3250, preferably less than 3150, limits included, are used in the reaction mixture of step i).

The addition of at least two zeolites of the FAU structural type with different molar ratios S1O2 / AI2O3, and a parameter P _ze less than 3250, preferably less than 3150, limits included, makes it possible in particular to adjust the SiO ₂ / AI ratio ₂ O ₃ of the precursor gel of a zeolite of AFX structural type obtained at the end of step i).

Step (i) of the process according to the invention consists in preparing an aqueous reaction mixture containing at least two zeolites of structural type FAU, at least one nitrogenous organic compound R, R being chosen from dihydroxide

1.5- bis (methylpiperidinium) pentane, dihydroxide

1.6- bis (methylpiperidinium) hexane or dihydroxide

1.7- bis (methylpiperidinium) heptane in the presence of at least one source of one or more alkali and / or alkaline-earth metal (s), to obtain a precursor gel of a zeolite of structural type AFX. The amounts of said reagents are adjusted as indicated above so as to give this gel a composition allowing the crystallization of a zeolite of AFX structural type.

It may be advantageous to add seeds of a zeolite of structural type AFX to the reaction mixture during said step i) of the process of the invention in order to reduce the time necessary for the formation of the crystals of a zeolite of type AFX structural and / or the total crystallization time. Said crystal seeds also promote the formation of said AFX structural type zeolite to the detriment of impurities. Such seeds comprise crystallized solids, in particular crystals of a zeolite of the AFX structural type. The crystalline seeds are generally added in a proportion of between 0.01 and 10% of the total mass of the sources of SiO ₂ and AI2O3 in anhydrous form used in the reaction mixture, said crystalline seeds not being taken into account in the mass sources of SiO ₂ and AI ₂ O ₃ . Said seeds are also not taken into account to determine the composition of the reaction mixture and / or the gel, defined further, that is to say in the determination of the different molar ratios of the composition of the reaction mixture.

Step i) of mixing is carried out until a homogeneous mixture is obtained, preferably for a duration greater than or equal to 30 minutes, preferably with stirring by any system known to a person skilled in the art at low or high shear rate.

At the end of step i), a homogeneous precursor gel is obtained.

It may be advantageous to implement a ripening of the reaction mixture before hydrothermal crystallization during said step i) of the process of the invention in order to control the size of the crystals of a zeolite of AFX structural type. Said ripening also promotes the formation of said AFX structural type zeolite to the detriment of impurities. The reaction mixture matures during said step i) of the process of the invention can be carried out at ambient temperature or at a temperature between 20 and 100 ° C. with or without stirring, for a period advantageously between 30 minutes and 48 hours.

In accordance with step (ii) of the process according to the invention, the precursor gel obtained at the end of step i) is subjected to a hydrothermal treatment, preferably carried out at a temperature between 120 ° C. and 220 ° C. for a period of between 12 hours and 15 days, until said zeolite of the AFX structural type is formed.

The precursor gel is advantageously placed under hydrothermal conditions under an autogenous reaction pressure, optionally by adding gas, for example nitrogen, at a temperature preferably between 120 ° C and 220 ° C, preferably between 150 ° C and 195 ° C., until the complete crystallization of an AFX structural type zeolite.

The time required to obtain crystallization varies between 12 hours and 15 days, preferably between 12 hours and 12 days, and more preferably between 12 hours and 8 days.

The reaction is generally carried out with stirring or in the absence of stirring, preferably with stirring. As the stirring system, any system known to the skilled person can be used, for example, inclined blades with counterpales, stirring turbines, Archimedes screws.

At the end of the reaction, after implementation of said step ii) of the preparation process according to the invention, the solid phase formed of a zeolite of AFX structural type is preferably filtered, washed and then dried. The drying is generally carried out at a temperature between 20 and 150 ° C, preferably between 60 and 100 ° C, for a period between 5 and 24 hours.

The dried zeolite can then be advantageously calcined. The AFX structural type zeolite, calcined, is generally analyzed by X-ray diffraction, this technique also making it possible to determine the purity of said zeolite obtained by the process of the invention.

The process of the invention leads to the formation of a zeolite of AFX structural type, of purity advantageously greater than 90%, preferably greater than 92%, very preferably greater than 95%, even more preferably greater than 99.8%. Very advantageously, the process of the invention leads to the formation of a zeolite of AFX structural type free from any other crystallized or amorphous phase, called pure zeolite. Said AFX structural type zeolite obtained, after the drying step, is then ready for subsequent steps such as calcination and ion exchange. For these steps, all the conventional methods known to those skilled in the art can be used.

According to the invention, loss of ignition (PAF) is understood to mean the percentage of loss of mass undergone by a solid compound, a mixture of solid compounds or a paste, preferably in the case of the present invention by the zeolite prepared, during a heat treatment at 1000 ° C. for 2 hours, in a static oven (muffle oven type), relative to the mass of the solid compound, of the mixture of solid compounds or of the initial paste, preferably in the case of the present invention with respect to the mass of dried zeolite tested. The loss on ignition generally corresponds to the loss of solvent (such as water) contained in the solids, but also to the elimination of organic compounds contained in the solid mineral constituents.

The loss on ignition of said AFX structural type zeolite obtained after drying and before calcination is generally between 5 and 15% by weight.

The calcination step of a zeolite of AFX structural type obtained according to the process of the invention is preferably carried out at a temperature between 450 and 700 ° C for a period between 2 and 20 hours.

The AFX structural type zeolite obtained at the end of the calcination step is devoid of any organic species and in particular of the organic structuring agent R.

At the end of said calcination step, the X-ray diffraction makes it possible to verify that the solid obtained by the process according to the invention is indeed a zeolite of AFX structural type. The purity obtained is advantageously greater than 90%, preferably greater than 92%, very preferably greater than 95%, even more preferably greater than 99.8% by weight. The solid obtained has the X-ray diffraction diagram including at least the lines listed in Table 1. Preferably, the X-ray diffraction diagram does not contain other lines of significant intensity (ie d intensity greater than about three times the background noise) than those listed in Table 1.

This diffraction diagram is obtained by radiocrystallographic analysis by means of a diffractometer using the conventional method of powders with the Και radiation of copper (λ = 1.5406A). From the position of the diffraction peaks represented by the angle 2Θ, we calculate, by the Bragg relation, the reticular equidistances d _h ki characteristic of the sample. The measurement error A (dhki) on dhki is calculated using the Bragg relation as a function of the absolute error Δ (2θ) assigned to the measurement of 2Θ. An absolute error Δ (2θ) equal to ± 0.02 ° is commonly accepted. The relative intensity l _re i assigned to each value of d _h ki is measured according to the height of the corresponding diffraction peak. The X-ray diffraction diagram of the crystalline solid of structural type AFX according to the invention comprises at least the lines with the values of d _h ki given in Table 1. In the column of d _hk |, the mean values of the inter-reticular distances 5 in Angstroms (A). Each of these values must be assigned the measurement error

A (dhki) between ± 0.6A and ± 0.01 A.

Table 1: Average values of d _h ki and relative intensities measured on an X-ray diffraction diagram of the crystallized solid of calcined AFX structural type

2 theta (°) dhkl (Â) Irel 2 theta (°) dhkl (Â) Irel 7.53 11,73 ff 26.16 3.40 mf 8.78 10.07 F 26.99 3.29 ff 11.75 7.52 FF 27.25 3.27 ff 13,02 6.79 m 27.62 3.23 ff 15.04 5.89 ff 28.26 3.16 m 15.70 5.64 f 28.74 3.10 ff 17.55 5.05 f 30.29 2.95 mf 18.07 4.91 m 30.63 2.92 m 19.59 4.53 ff 31.22 2.87 ff 19,91 4.46 f 31.65 2.82 mf 20.43 4.34 F 31.94 2.80 ff 21.89 4.06 FF 32.76 2.73 ff 22.32 3.98 ff 33.92 2.64 mf 22.61 3.93 ff 34.31 2.61 ff 23,00 3.86 ff 34.82 2.57 f 23.56 3.77 ff 35.38 2.54 ff 23.86 3.7 ff 35.85 2.50 ff 24,10 3.69 ff 37.47 2.40 ff

where FF = very strong; F = strong; m = medium; mf = medium weak; f = weak; ff = very weak. The relative intensity l _re i is given in relation to a relative intensity scale where a value of 100 is assigned to the most intense line of the X-ray diffraction diagram: ff <15; 15 <f <30; 30 <mf <50; 50 <m <65; 65 <F <85;FF> 85.

X-ray fluorescence spectrometry (FX) is a chemical analysis technique using a physical property of matter, X-ray fluorescence. It allows the analysis of the majority of chemical elements from Beryllium (Be) in concentration ranges from a few ppm to 100%, with precise and reproducible results. X-rays are used to excite the atoms in the sample, which causes them to emit X-rays with energy 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.

It is also advantageous to obtain the protonated form of the zeolite of the AFX structural type obtained by the process according to the invention. Said hydrogen form can be obtained by carrying out an ion exchange with an acid, in particular a strong mineral acid such as hydrochloric, sulfuric or nitric acid, or with a compound such as chloride, sulphate or ammonium nitrate . The ion exchange can be carried out by suspending said zeolite of the AFX structural type in one or more stages with the ion exchange solution. Said zeolite can be calcined before or after ion exchange, or between two stages of ion exchange. The zeolite is preferably calcined before the ion exchange, in order to remove any organic substance included in the porosity of the zeolite, insofar as the ion exchange is thereby facilitated.

The AFX structural type zeolite obtained by the process of the invention can be used after ion exchange as an acid solid for catalysis in the fields of refining and petrochemistry. It can also be used as an adsorbent or as a molecular sieve.

EXAMPLES

The invention is illustrated by the following examples which are in no way limiting in nature.

Example 1: preparation of 1 .e-bisfmethylpiperidiniumjhexane dihydroxide (structuring R).

g of 1,6-dibromohexane (0.20 mole, 99%, Alfa Aesar) are added to a 1 L flask containing 50 g of N-methylpiperidine (0.51 mole, 99%, Alfa Aesar) and 200 mL d ethanol. The reaction medium is stirred and brought to reflux for 5 hours. The mixture is then cooled to room temperature and then filtered. The mixture is poured into 300 ml of cold diethyl ether then the precipitate formed is filtered and washed with 100 ml of diethyl ether. The solid obtained is recrystallized from an ethanol / ether mixture. The solid obtained is dried under vacuum for 12 hours. 71 g of a white solid are obtained (ie a yield of 80%).

The product has the expected ¹ H NMR spectrum. ¹ H NMR (D ₂ O, ppm / TMS): 1.27 (4H, m); 1.48 (4H, m); 1.61 (4H, m); 1.70 (8H, m); 2.85 (6H, s); 3.16 (12H, m).

18.9 g of Ag ₂ O (0.08 mol, 99%, Aldrich) are added to a 250 ml teflon beaker containing 30 g of the dibromide structuring agent.

1.6- bis (methylpiperidinium) hexane (0.07 mole) and 100 mL of deionized water. The reaction medium is stirred protected from light for 12 hours. The mixture is then filtered. The filtrate obtained is composed of an aqueous solution of dihydroxide

1.6- bis (methylpiperidinium) hexane. The assay of this species is carried out by proton NMR using formic acid as a standard.

Example 2: preparation of an AFX structural type zeolite according to the invention.

0.266 g of a FAU structural type zeolite (CBV600 Zeolyst, SiO ₂ / AI ₂ O ₃ = 5.46, PAF = 12.65%,% in the mixture of FAU zeolites in anhydrous form = 27.54, P _ze = 150) were mixed with 4.81 g of deionized water. 0.691 g of a FAU structural type zeolite (CBV712 Zeolyst, SiO ₂ / AI ₂ O ₃ = 11.46, PAF = 12.81%,% in the mixture of zeolites FAU = 72.46, P _ze = 830) are added to the preceding mixture, the preparation obtained is kept under stirring for 10 minutes. 2.875 g of an aqueous solution of 1,6-bis (methylpiperidinium) hexane dihydroxide (20.91% by weight) prepared according to Example 1, are added to the preceding mixture, and the mixture is stirred for 10 minutes . Subsequently, 0.327 g of a 20% by weight aqueous solution of solid sodium hydroxide of 98% by weight purity (Aldrich) was incorporated into the synthesis mixture which is stirred for half an hour. The molar composition of the mixture is as follows: 60 S1O2: 6.7 AI2O3: 10 R: 4.3 Na ₂ O: 2204 H ₂ O, i.e. an S1O2 / AI2O3 ratio of 9. The precursor gel is then transferred, after homogenization in an autoclave. The autoclave is closed and then heated for 4 days at 180 ° C. with stirring at 35 rpm with a spit system. The crystallized product obtained is filtered, washed with deionized water, then dried overnight at 100 ° C. The loss on ignition (PAF) of the dry product is 15% by weight. The solid is then introduced into a muffle furnace where a calcination step is carried out: the calcination cycle includes a rise in temperature of 1.5 ° C / min to 200 ° C, a plateau at 200 ° C maintained for 2 hours, a temperature rise of 1 ° C / min to 550 ° C followed by a plateau at 550 ° C maintained for 8 hours then a return to room temperature.

The calcined solid product was analyzed by X-ray diffraction and identified as being made up of at least about 97% by weight of an AFX structural type zeolite. The X-ray fluorescence analysis gives a molar ratio S1O2 / AI2O3 = 9.8.

Example 3: Preparation of an AFX Structural Type Zeolite According to the Invention

0.266 g of a FAU structural type zeolite (CBV600 Zeolyst, SiO2 / AI ₂ O3 = 5.46, PAF = 12.65%,% in the mixture of FAU zeolites in anhydrous form = 27.54, P _ze = 150 ) were mixed with 4.81 g of deionized water. 0.691 g of a FAU structural type zeolite (CBV712 Zeolyst, SiO ₂ / AI ₂ O3 = 11.46, PAF = 12.81%,% in the mixture of zeolites FAU = 72.46, P _ze = 830) are added to the above mixture, the preparation obtained is kept stirring for 10 minutes. 2.875 g of an aqueous solution of 1,6-bis (methylpiperidinium) hexane dihydroxide (20.91% by weight) prepared according to Example 1 are added to the preceding mixture, and the mixture is kept under stirring for 10 minutes. Subsequently, 0.327 g of a 20% by weight aqueous solution of sodium hydroxide (98% by weight, Aldrich) was incorporated into the synthesis mixture which is stirred for half an hour. The molar composition of the mixture is as follows: 60 S1O2: 6.7

AI2O3: 10 R: 4.3 Na ₂ O: 2204 H ₂ O, ie an S1O2 / AI2O3 ratio of 9. The precursor gel is then transferred, after homogenization in an autoclave. The autoclave is closed and then heated for 4.5 days at 165 ° C. with stirring at 35 rpm with a spit system. The crystallized product obtained is filtered, washed with deionized water, then dried overnight at 100 ° C. The loss on ignition (PAF) of the dry product is 9.2% by weight. The solid is then introduced into a muffle furnace where a calcination step is carried out: the calcination cycle includes a rise in temperature of 1.5 ° C / min to 200 ° C, a plateau at 200 ° C maintained for 2 hours, a temperature rise of 1 ° C / min to 550 ° C followed by a plateau at 550 ° C maintained for 8 hours then a return to room temperature.

The calcined solid product was analyzed by X-ray diffraction and identified as being made up of at least about 97% by weight of an AFX structural type zeolite. The X-ray fluorescence analysis gives a molar ratio S1O2 / AI2O3 = 9.5.

Example 4: Preparation of an AFX structural type zeolite according to the invention 0.179 g of a FAU structural type zeolite (CBV600 Zeolyst, δίθ2 / ΑΙ ₂ θ3 = 5.46, PAF = 12.65%,% in the mixture of FAU zeolites in anhydrous form = 20.64, Pze = 113) were mixed with 4.86 g of deionized water. 0.643 g of a FAU structural type zeolite (CBV720 Zeolyst, δί0 ₂ / ΑΙ ₂ 03 = 33.52, PAF = 6.63%,% in the mixture of FAU zeolites = 79.36, P _ze = 2660) are added to the above mixture, the preparation obtained is kept stirring for 10 minutes. 2.891 g of an aqueous solution of 1,6-bis (methylpiperidinium) hexane dihydroxide (20.91% by weight) prepared according to example 1, are added to the preceding mixture, and the preparation is kept under stirring for 10 minutes . Subsequently, 0.428 g of a 20% by weight aqueous solution of solid sodium hydroxide of 98% by weight purity (Aldrich) was incorporated into the synthesis mixture which is stirred for half an hour. The molar composition of the mixture is as follows: 60 δίθ2: 3.3 AI2O3: 10 R: 5.6 Na ₂ O: 2204 H ₂ O, i.e. a ratio δίθ2 / ΑΙ ₂ θ3 of 18. The precursor gel is then transferred, after homogenization in an autoclave. The autoclave is closed and then heated for 6 days at 180 ° C. with stirring at 35 rpm with a spit system. The crystallized product obtained is filtered, washed with deionized water and then dried overnight at 100 ° C. The loss on ignition (PAF) of the dry product is 9.1% by weight. The solid is then introduced into a muffle furnace where a calcination step is carried out: the calcination cycle includes a rise in temperature of 1.5 ° C / min to 200 ° C, a plateau at 200 ° C maintained for 2 hours, a temperature rise of 1 ° C / min to 550 ° C followed by a plateau at 550 ° C maintained for 8 hours then a return to room temperature.

The calcined solid product was analyzed by X-ray diffraction and identified as being constituted by a zeolite of pure AFX structural type, that is to say of purity greater than 99.8% by weight. The diffraction diagram carried out on the solid of calcined AFX structural type is given in FIG. 2. The product has a molar ratio S1O2 / AI2O3 of 12.7 as determined by X-ray fluorescence.

Example 5: Preparation of an AFX Structural Type Zeolite According to the Invention

0.179 g of a FAU structural type zeolite (CBV600 Zeolyst, SiO ₂ / AI ₂ O ₃ = 5.46, PAF = 12.65%,% in the mixture of zeolites FAU = 20.64, P _ze = 113) were mixed with 4.94 g of deionized water. 0.644 g of a zeolite of structural type FAU (CBV720 Zeolyst, SiO ₂ / AI ₂ O3 = 33.52, PAF = 6.63%,% in the mixture of zeolites FAU = 79.36, P _ze = 2660) are added to the above mixture, the preparation obtained is kept stirring for 10 minutes. 2.896 g of an aqueous solution of 1,6-bis (methylpiperidinium) hexane dihydroxide (20.91% by weight) prepared according to Example 1, are added to the preceding mixture, and the preparation is stirred for 10 minutes . Subsequently, 0.329 g of a 20% by weight aqueous solution of sodium hydroxide (98% by weight, Aldrich) was incorporated into the synthesis mixture which is stirred for half an hour. The molar composition of the mixture is as follows: 60 SiO ₂ : 3.3 AI ₂ O ₃ : 10 R:

4.3 Na ₂ O: 2204 H ₂ O, ie an SiO ₂ / AI ₂ O ₃ ratio of 18. The precursor gel is then transferred, after homogenization in an autoclave. The autoclave is closed and then heated for 6 days at 180 ° C. with stirring at 35 rpm with a rotisserie system. The crystallized product obtained is filtered, washed with deionized water and then dried overnight at 100 ° C. The loss on ignition (PAF) of the dry product is 9.1% by weight. The solid is then introduced into a muffle furnace where a calcination step is carried out: the calcination cycle includes a rise in temperature of 1.5 ° C / min to 200 ° C, a plateau at 200 ° C maintained for 2 hours, a temperature rise of 1 ° C / min to 550 ° C followed by a plateau at 550 ° C maintained for 8 hours then a return to room temperature.

The calcined solid product was analyzed by X-ray diffraction and identified as consisting of a zeolite of the pure AFX structural type, that is to say of purity greater than 99.8% by weight. The product has an S1O2 / AI2O3 molar ratio of 13.3 as determined by X-ray fluorescence. A scan of the scanning electron microscope (SEM) of the AFX zeolite obtained according to Example 5 is given in FIG. 3.

Example 6 Preparation of an AFX Structural Type Zeolite According to the Invention

0.179 g of a FAU structural type zeolite (CBV600 Zeolyst, SiO ₂ / AI ₂ O3 = 5.46, PAF = 12.65%,% in the mixture of FAU zeolites in anhydrous form = 20.64, Pze = 113 ) were mixed with 4.86 g of deionized water. 0.643 g of a FAU structural type zeolite (CBV720 Zeolyst, SiO2 / AI ₂ O3 = 33.52, PAF = 6.63%,% in the mixture of zeolites FAU = 79.36, P _ze = 2660) with the preceding mixture, the preparation obtained is kept under stirring for 10 minutes. 2.891 g of an aqueous solution of 1,6-bis (methylpiperidinium) hexane dihydroxide (20.91% by weight) prepared according to example 1, are added to the preceding mixture, and the preparation is kept under stirring for 10 minutes . Subsequently, 0.428 g of a 20% by weight aqueous solution of solid sodium hydroxide of 98% by weight purity (Aldrich) was incorporated into the synthesis mixture which is stirred for half an hour. The molar composition of the mixture is as follows: 60 SiO ₂ : 3.3 AI ₂ O ₃ : 10 R: 5.6 Na ₂ O: 2204 H ₂ O, i.e. an S1O2 / AI2O3 ratio of 18. The precursor gel is then transferred, after homogenization in an autoclave. The autoclave is closed and then heated for 6 days at 170 ° C. with stirring at 35 rpm with a spit system. The crystallized product obtained is filtered, washed with deionized water and then dried overnight at 100 ° C. The loss on ignition (PAF) of the dry product is 9.2% by weight. The solid is then introduced into a muffle furnace where a calcination step is carried out: the calcination cycle includes a rise in temperature of 1.5 ° C / min to 200 ° C, a plateau at 200 ° C maintained for 2 hours, a temperature rise of 1 ° C / min to 550 ° C followed by a plateau at 550 ° C maintained for 8 hours then a return to room temperature.

The calcined solid product was analyzed by X-ray diffraction and identified as consisting of a zeolite of the pure AFX structural type, that is to say of purity greater than 99.8% by weight. The product has an S1O2 / AI2O3 molar ratio of 13.10 as determined by X-ray fluorescence.

Example 7: Preparation of an AFX Structural Type Zeolite According to the Invention

0.179 g of a FAU structural type zeolite (CBV600 Zeolyst, SiO ₂ / AI ₂ O3 = 5.46, PAF = 12.65%,% in the mixture of zeolites FAU = 20.64, P _ze = 113) have been mixed with 4.94 g of deionized water. 0.644 g of a FAU structural type zeolite (CBV720 Zeolyst, SiO2 / AI ₂ O3 = 33.52, PAF = 6.63%,% in the mixture of zeolites FAU = 79.36, P _ze = 2660) with the preceding mixture, the preparation obtained is kept under stirring for 10 minutes. 2.896 g of an aqueous solution of 1,6-bis (methylpiperidinium) hexane dihydroxide (20.91% by weight) prepared according to Example 1, are added to the preceding mixture, and the preparation is stirred for 10 minutes . Subsequently, 0.329 g of a 20% by weight aqueous solution of sodium hydroxide (98% by weight, Aldrich) was incorporated into the synthesis mixture which is stirred for half an hour. The molar composition of the mixture is as follows: 60 S1O2: 3.3 AI2O3: 10 R:

4.3 Na ₂ O: 2204 H ₂ O, ie an S1O2 / AI2O3 ratio of 18. The precursor gel is then transferred, after homogenization in an autoclave. The autoclave is closed and then heated for 6 days at 170 ° C. with stirring at 35 rpm with a rotisserie system. The crystallized product obtained is filtered, washed with deionized water and then dried overnight at 100 ° C. The loss on ignition (PAF) of the dry product is 9.1% by weight. The solid is then introduced into a muffle furnace where a calcination step is carried out: the calcination cycle includes a rise in temperature of 1.5 ° C / min to 200 ° C, a plateau at 200 ° C maintained for 2 hours, a temperature rise of 1 ° C / min to 550 ° C followed by a plateau at 550 ° C maintained for 8 hours then a return to room temperature.

The calcined solid product was analyzed by X-ray diffraction and identified as consisting of a zeolite of the pure AFX structural type, that is to say of purity greater than 99.8% by weight. The product has an S1O2 / AI2O3 molar ratio of 13.26 as determined by X-ray fluorescence.

Example 8 Preparation of an AFX Structural Type Zeolite According to the Invention

0.630 g of a FAU structural type zeolite (CBV712 Zeolyst, SiO2 / AI ₂ O3 = 12.81, PAF = 12.81%,% in the mixture of FAU zeolites = 70.85, P _ze = 908) were mixed with 4.53 g of deionized water. 0.247 g of a FAU structural type zeolite (CBV780 Zeolyst, SiO2 / AI ₂ O3 = 98.22, PAF = 8.52%,% in the mixture of zeolites FAU = 29.15, P _ze = 2863) with the preceding mixture, the preparation obtained is kept under stirring for 10 minutes. 3.295 g of an aqueous solution of 1,6-bis (methylpiperidinium) hexane dihydroxide (18.36% by weight) prepared according to example 1, are added to the preceding mixture, and the mixture is stirred for 10 minutes . Subsequently, 0.329 g of a 20% by weight aqueous solution of sodium hydroxide (98% by weight, Aldrich) was incorporated into the synthesis mixture which is stirred for half an hour. The molar composition of the mixture is as follows: 60 SiO ₂ : 3.75 AI2O3: 10 R:

4.3 Na ₂ O: 2204 H ₂ O, ie an S1O2 / AI2O3 ratio of 16. The precursor gel is then transferred, after homogenization in an autoclave. The autoclave is closed and then heated for 6 days at 180 ° C. with stirring at 35 rpm with a rotisserie system. The crystallized product obtained is filtered, washed with deionized water and then dried overnight at 100 ° C. The loss on ignition (PAF) of the dry product is 9.0% by weight. The solid is then introduced into a muffle furnace where a calcination step is carried out: the calcination cycle includes a rise in temperature of 1.5 ° C / min to 200 ° C, a plateau at 200 ° C maintained for 2 hours, a temperature rise of 1 ° C / min to 550 ° C followed by a plateau at 550 ° C maintained for 8 hours then a return to room temperature.

The calcined solid product was analyzed by X-ray diffraction and identified as consisting of a zeolite of the pure AFX structural type, that is to say of purity greater than 99.8% by weight. The product has an S1O2 / AI2O3 molar ratio of 13.0 as determined by X-ray fluorescence.

Example 9 Preparation of an AFX Structural Type Zeolite According to the Invention

0.057 g of a zeolite of structural type FAU (CBV712 Zeolyst, SiO ₂ / AI ₂ O3 = 11.42, PAF = 12.81%,% in the mixture of zeolites FAU = 6.71, P _ze = 77) have been mixed with 4.56 g of deionized water. 0.735 g of a FAU structural type zeolite (CBV720 Zeolyst, SiO2 / AI ₂ O3 = 33.52, PAF = 6.63%,% in the mixture of zeolites FAU = 93.29, P _ze = 3127) are added with the preceding mixture, the preparation obtained is kept under stirring for 10 minutes. 3.308 g of an aqueous solution of 1,6-bis (methylpiperidinium) hexane dihydroxide (18.36% by weight) prepared according to example 1, are added to the preceding mixture, and the preparation is kept under stirring for 10 minutes . Subsequently, 0.330 g of a 20% by weight aqueous solution of sodium hydroxide (98% by weight, Aldrich) was incorporated into the synthesis mixture which is kept under stirring for half an hour. The molar composition of the mixture is as follows: 60 SiO ₂ : 2.0 AI2O3: 10 R:

4.3 Na ₂ O: 2204 H ₂ O, ie an S1O2 / AI2O3 ratio of 30. The precursor gel is then transferred, after homogenization in an autoclave. The autoclave is closed and then heated for 6 days at 180 ° C. with stirring at 35 rpm with a rotisserie system. The crystallized product obtained is filtered, washed with deionized water and then dried overnight at 100 ° C. The loss on ignition (PAF) of the dry product is 9.0% by weight. The solid is then introduced into a muffle furnace where a calcination step is carried out: the calcination cycle includes a rise in temperature of 1.5 ° C / min to 200 ° C, a plateau at 200 ° C maintained for 2 hours, a temperature rise of 1 ° C / min to 550 ° C followed by a plateau at 550 ° C maintained for 8 hours then a return to room temperature.

The calcined solid product was analyzed by X-ray diffraction and identified as being made up of at least about 98% by weight of an AFX structural type zeolite. The product has an S1O2 / AI2O3 molar ratio of 11.76 as determined by X-ray fluorescence.

Example 10: Preparation of an AFX Structural Type Zeolite According to the Invention

0.411 g of a FAU structural type zeolite (CBV712 Zeolyst, S1O2 / AI2O3 = 11.42, PAF = 12.81%,% in the mixture of zeolites FAU = 47.35, P _ze = 541) were mixed with 4.52 g of deionized water. 0.427 g of a FAU structural type zeolite (CBV720 Zeolyst, SiO2 / AI ₂ O3 = 33.52, PAF = 6.63%,% in the mixture of zeolites FAU = 52.65, P _ze = 1765) with the preceding mixture, the preparation obtained is kept under stirring for 10 minutes. 3.298 g of an aqueous solution of 1,6-bis (methylpiperidinium) hexane dihydroxide (18.36% by weight) prepared according to example 1, are added to the preceding mixture, and the preparation is kept under stirring for 10 minutes . Subsequently, 0.329 g of a 20% by weight aqueous solution of sodium hydroxide (98% by weight, Aldrich) was incorporated into the synthesis mixture which is stirred for half an hour. The molar composition of the mixture is as follows: 60 SiO ₂ : 3.3 AI ₂ O ₃ : 10 R:

4.3 Na ₂ O: 2204 H ₂ O, ie an SiO ₂ / AI ₂ O ₃ ratio of 18. The precursor gel is then transferred, after homogenization in an autoclave. The autoclave is closed and then heated for 6 days at 180 ° C. with stirring at 35 rpm with a rotisserie system. The crystallized product obtained is filtered, washed with deionized water and then dried overnight at 100 ° C. The loss on ignition (PAF) of the dry product is 9.1% by weight. The solid is then introduced into a muffle furnace where a calcination step is carried out: the calcination cycle includes a rise in temperature of 1.5 ° C / min to 200 ° C, a plateau at 200 ° C maintained for 2 hours, a temperature rise of 1 ° C / min to 550 ° C followed by a plateau at 550 ° C maintained for 8 hours then a return to room temperature.

The calcined solid product was analyzed by X-ray diffraction and identified as consisting of a zeolite of pure AFX structural type, that is to say of purity greater than 99.8% by weight. The product has a SiO ₂ / AI ₂ O ₃ molar ratio of 11.80 as determined by X-ray fluorescence.

Example 11: Preparation of a zeolite of AFX structural type according to the invention 0.177 g of a zeolite of FAU structural type (CBV100 Zeolyst, SiO ₂ / AI ₂ O ₃ = 4.78, PAF = 21.58%,% in the mixture of zeolites FAU = 18.31, P _ze = 87.5) were mixed with 4.53 g of deionized water. 0.663 g of a FAU structural type zeolite (CBV720 Zeolyst, SiO ₂ / AI ₂ O ₃ = 33.52, PAF = 6.63%,% in the mixture of zeolites FAU = 81.69, P _ze = 2738) are added to the preceding mixture, the preparation obtained is kept under stirring for 10 minutes. 3.298 g of an aqueous solution of 1,6-bis (methylpiperidinium) hexane dihydroxide (18.36% by weight) prepared according to example 1, are added to the preceding mixture, and the preparation is kept under stirring for 10 minutes . Subsequently, 0.329 g of a 20% by weight aqueous solution of sodium hydroxide (98% by weight, Aldrich) was incorporated into the synthesis mixture which is stirred for half an hour. The molar composition of the mixture is as follows: 60 S1O2: 3.3 AI2O3:

A: 4.3 Na ₂ O: 2204 H ₂ O, ie an S1O2 / AI2O3 ratio of 18. The precursor gel is then transferred, after homogenization in an autoclave. The autoclave is closed and then heated for 6 days at 180 ° C. with stirring at 35 rpm with a 5 spit system. The crystallized product obtained is filtered, washed with deionized water and then dried overnight at 100 ° C. The loss on ignition (PAF) of the dry product is 9.1% by weight.

The solid is then introduced into a muffle furnace where a calcination step is carried out: the calcination cycle includes a rise in temperature of 1.5 ° C / min to 200 ° C, a plateau at 200 ° C maintained for 2 hours, a temperature rise of 1 ° C / min to 550 ° C followed by a plateau at 550 ° C maintained for hours and then a return to room temperature.

The calcined solid product was analyzed by X-ray diffraction and identified as consisting of a zeolite of the pure AFX structural type, that is to say of purity greater than 99.8% by weight. The product has an S1O2 / AI2O3 molar ratio of 12.50 as determined by X-ray fluorescence.

Claims (12)

1. Process for the preparation of an AFX structural type zeolite comprising at least the following steps: i) mixing in an aqueous medium, at least two zeolites of structural type FAU, each of said zeolites of structural type FAU having a SiO ₂ / AI ₂ O ₃ molar ratio of between 2 and 200, limits included, and a parameter P _2e , corresponding to the respective percentage (expressed in%) of each of said FAU zeolites in anhydrous form relative to all of the FAU zeolites in anhydrous form multiplied by the molar ratio SiO ₂ / AI ₂ O ₃ of each of said FAU zeolites, lower at 3250, preferably less than 3150, of an organic nitrogen compound R, R being chosen from 1.5bis dihydroxide (methylpiperidinium) pentane, dihydroxide 1.6- bis (methylpiperidinium) hexane or dihydroxide 1.7- bis (methylpiperidinium) heptane, from at least one source of at least one alkali and / or alkaline-earth metal M of valence η, n being an integer greater than or equal to 1, chosen from lithium, potassium, sodium, magnesium and calcium and the mixture of at least two of these metals, the reaction mixture having the following molar composition: (SiO ₂ (fau)) / (AI ₂ O ₃ (fau)) between 2 and 32, preferably between 3 and 30 H ₂ O / (SîO ₂ (fau)) between 1 and 100, preferably between 5 and 60 R / (SiO _{2 (} FAU)) between 0.01 to 0.6, preferably between 0.05 and 0.5 M ₂ / _n O / (SiO ₂ (fau)) between 0.005 and 0, 45, preferably between 0.05 and 0.25, limits included, in which SiO _{2 (FA} u) is the quantity of SiO ₂ provided by said at least two FAU zeolites, and AI ₂ O ₃ (fau) is the quantity AI ₂ O ₃ provided by said at least two FAU zeolites, 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 between 120 ° C and 220 ° C, for a period of between 12 hours and 15 days. 2. Method according to the preceding claim wherein R is 1,6-bis (methylpiperidinium) hexane dihydroxide. 3. Method according to one of the preceding claims in which M is sodium. 4. The method of claim 3 wherein the source of at least one alkali and / or alkaline earth metal M is sodium hydroxide. 5. Method according to one of the preceding claims wherein each of said zeolites of FAU structural type has a SiO ₂ / AI ₂ O ₃ molar ratio of between 3 and 100, limits included. 6. Method according to one of the preceding claims in which crystalline seeds of a zeolite of the AFX structural type are added to the reaction mixture of step i), preferably in an amount of between 0.01 and 10% by weight relative to to the total weight of the sources of SiO ₂ and of AI ₂ O ₃ in anhydrous form present in said mixture, said crystalline seeds not being taken into account in the total mass of the sources of SiO ₂ and of AI ₂ O ₃ . 7. Method according to one of the preceding claims wherein step i) comprises a step of maturing the reaction mixture at a temperature between 20 and 100 ° C, with or without stirring, for a time between 30 minutes and 48 hours. 8. Method according to one of claims 1 to 7 wherein 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 195 ° C, for a period of between 12 hours and 15 days, preferably between 12 hours and 12 days, very preferably between 12 hours and 8 days. 9. Method according to one of the preceding claims wherein the solid phase obtained at the end of step ii) is 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. 10. The method of claim 9 wherein the dried zeolite is then calcined at a temperature between 450 and 700 ° C for a period between 2 and 20 hours, the calcination may be preceded by a gradual rise in temperature. 5 11. AFX structural type zeolite with a SiO ₂ / AI ₂ O ₃ ratio of between 4 and 100, limits included, obtained by the preparation process according to one of claims 1 to 10. 12. AFX structural type zeolite with a SiO ₂ / AI ₂ O ₃ ratio of between 4 and 100, limits included, obtained by the preparation process according to claim ίο 10 for which the mean values of d _hk i and relative intensities measured over an X-ray diffraction pattern are as follows: 2 theta (°) dhkl (Â) Irel 2 theta (°) dhkl (A) Irel 7.53 11,73 ff 26.16 3.40 mf 8.78 10.07 F 26.99 3.29 ff 11.75 7.52 FF 27.25 3.27 ff 13,02 6.79 m 27.62 3.23 ff 15.04 5.89 ff 28.26 3.16 m 15.70 5.64 f 28.74 3.10 ff 17.55 5.05 f 30.29 2.95 mf 18.07 4.91 m 30.63 2.92 m 19.59 4.53 ff 31.22 2.87 ff 19,91 4.46 f 31.65 2.82 mf 20.43 4.34 F 31.94 2.80 ff 21.89 4.06 FF 32.76 2.73 ff 22.32 3.98 ff 33.92 2.64 mf 22.61 3.93 ff 34.31 2.61 ff 23,00 3.86 ff 34.82 2.57 f 23.56 3.77 ff 35.38 2.54 ff 23.86 3.7 ff 35.85 2.50 ff 24,10 3.69 ff 37.47 2.40 ff where FF = very strong; F = strong; m = medium; mf = medium weak; f = weak; ff = very low, the relative intensity l _re i being given in relation to a relative intensity scale where a value of 100 is assigned to the most intense line of the X-ray diffraction diagram: ff <15; 15 <f <30; 30 <mf <50; 50 <m <65; 65 <F <85;FF> 85.