Synthesis of a high purity izm-8 zeolite of fer framework type

Abstract

The present invention relates to a new method for preparing an IZM-8 zeolite of FER framework type, which makes it possible to synthesize an IZM-8 zeolite of FER framework type by converting / transforming a zeolite of FAU framework type under hydrothermal conditions. In particular, said new method makes it possible to synthesize an IZM-8 zeolite of FER framework type, starting from a zeolite of FAU framework type used as a source of silicon and aluminum and a specific organic or structuring molecule comprising a quaternary ammonium function, N-ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium hydroxide. Said IZM-8 zeolite of FER framework type obtained according to the method of the invention advantageously finds application as a catalyst, adsorbent or separating agent.

Description

[0001] SYNTHESIS OF A HIGH PURITY IRON STRUCTURAL TYPE IZM-8 ZEOLITE

[0002] TECHNICAL FIELD

[0003] The present invention relates to a new process for preparing an IZM-8 zeolite of FER structure type. This new process makes it possible to carry out the synthesis of an IZM-8 zeolite of FER structure type by transformation under hydrothermal conditions of a zeolite of FAU structure type. In particular, said new process makes it possible to carry out the synthesis of an IZM-8 zeolite of FER structure type, from a zeolite of FAU structure type used as a source of silicon and aluminum and from a specific organic molecule or structuring agent comprising a quaternary ammonium function, N-ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium hydroxide. Said IZM-8 zeolite of FER structure type obtained according to the process of the invention advantageously finds its application as a catalyst, adsorbent or separation agent.

[0004] PREVIOUS ART

[0005] Crystallized microporous materials, such as zeolites or silicoaluminophosphates, are solids widely used in the petroleum industry as catalysts, catalyst supports, adsorbents, or separation agents. Although many microporous crystalline structures have been discovered, the refining and petrochemical industries are always looking for new zeolite structures that exhibit specific properties for applications such as gas purification or separation, carbon species conversion, or others.

[0006] The FER structural type includes the following zeolites: ZSM-35, Nu-23, FU-9, ISI-6. The FER structural type has a two-dimensional channel system of 10 MR with a pore size of 0.42 x 0.54 nm interconnected by a channel system of 8 MR with a pore size of 0.35 x 0.48 nm (Exxon Mobil Oil Corp. US4107195, J. Li et al. Catl. Let., 20, (1993) 345).

[0007] Zeolites with the structural type FER have been synthesized using organic nitrogen species such as pyrrolidine (J. Pérez-Pari ente et al. Micropor. Mesopor. Mat., 129, (2010) 164; LY Xu et al. Micropor. Mesopor. Mat., 240, (2017) 189), pyridine in the presence of NaF (T. Okubo et al. Micropor. Mesopor. Mat., 181, (2013) 154), and cyclohexylamine (W. Qingxia et al. Chinese Journal of Catalysis, 24, (2003) 531).

[0008] V. Valtchev et al (Micropor. Mesopor. Mat., 200, (2014) 334) prepared a zeolite of structural type FER in the presence of Na-ethylenediamine, Na-K and Na-pyrrolidine in order to study the effect of the mixture of two structuring agents on the crystallization time and the morphology of the material obtained. We can also mention the use of organic compounds tetrahydrofuran as structuring agent for the preparation of zeolite of structural type FER (YC Long et al. Chem. Commun, 19, (2000), 1893; YC Long et al. Micropor. Mesopor. Mat., 119, (2009) 60).

[0009] J. Pérez-Pariente et al. (Chem. Mater. 19, 23 (2007), 5617; Catal. Today, 179, (2012) 16) used a mixture of organic cations tetramethylammonium and benzylmethylpyrrolidinium as structuring agents in a fluorinated medium to prepare a zeolite of structural type FER in the absence of inorganic cations.

[0010] SUMMARY OF THE INVENTION

[0011] Surprisingly, the Applicant has developed a process for preparing a FER type zeolite from a FAU structural type zeolite, in the presence of a specific structuring agent, making it possible to produce, in a simple and reproducible manner, a high, or even very high purity, FER type zeolite, having a SiC^ / AhCh ratio between 15 and 30, preferably between 10 and 25, called IZM-8. Said process for preparing a FER structural type IZM-8 zeolite makes it possible to synthesize a FER structural type IZM-8 zeolite by conversion / transformation under hydrothermal conditions of a FAU structural type zeolite.In particular, said new process makes it possible to carry out the synthesis of an IZM-8 zeolite of FER structural type, from a zeolite of FAU structural type used as a source of silicon and aluminum and from a specific organic molecule or structuring agent comprising a quaternary ammonium function, N-ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium hydroxide. Said IZM-8 zeolite of FER structural type obtained according to the process of the invention advantageously finds its application as a catalyst, adsorbent or separation agent.

[0012] More particularly, the invention relates to a process for preparing a high-purity IZM-8 zeolite of FER structural type comprising at least the following steps: i) mixing in an aqueous medium, a zeolite of FAU structural type as a source of silicon in the form of SiC>2 oxide and aluminum in the form of AI2O3 oxide, a nitrogenous organic compound R, R being N-ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium hydroxide, at least one alkali metal and / or an alkaline-earth metal M of valence n, n being an integer greater than or equal to 1, and optionally at least one source of a trivalent element in the form of Y2O3 oxide, the mixture having the following molar composition:

[0013] (SiC>2 (FAU)) / (AhO3 (FAU) + Y2O3) between 6 and 200, preferably between 6 and 100 H2O / (SiO2 (FAU)) between 1 and 16, preferably between 5 and 14

[0014] R / (SiC>2 (FAU)) between 0.01 and 0.5, preferably between 0.04 and 0.3

[0015] M2 / nO / (SiO2(FAU)) between 0.005 and 0.45, preferably between 0.05 and 0.2 in which Y is one or more trivalent element(s) chosen from the group formed by the following elements: aluminum, boron, gallium, SiC>2 (FAU) being the quantity of SiC>2 provided by the FAU zeolite, and ALOS ^AU) being the quantity of AI2O3 provided by the FAU zeolite, 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 metals, until a homogeneous precursor gel is obtained; ii) maturing the homogeneous precursor gel obtained at the end of said step i) at a temperature between 15 and 100°C, with or without stirring, for a period between 10 minutes and 48 hours;iii) hydrothermal treatment of said precursor gel obtained at the end of step ii) at a temperature of between 120 and 220°C for a period of between 12 hours and 7 days, inclusive, until said IZM-8 zeolite of structural type FER is formed.;

[0016] Preferably, M is sodium.

[0017] Preferably, the source of at least one alkali metal M is sodium hydroxide.

[0018] It could be aluminum.

[0019] Crystalline seeds of a zeolite of structural type FER may be added to the reaction mixture of step i) or to the homogeneous precursor gel of step ii), in an amount of between 0.01 and 10% of the total mass of the sources of said element(s) Si and Al in anhydrous form used in the reaction mixture, said crystalline seeds not being taken into account in the total mass of the sources of the elements Si and Al.

[0020] The ripening of step ii) can be carried out with stirring at room temperature for a period of between 6 and 24 hours, inclusive.

[0021] The hydrothermal treatment of step iii) can be carried out under autogenous reaction pressure.

[0022] The hydrothermal treatment of step iii) can be carried out at a temperature between 140 and 195°C.

[0023] After carrying out said step iii), the solid phase formed from an IZM-8 zeolite of FER structural type obtained at the end of step iii) 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.

[0024] Said 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. The invention also relates to an IZM-8 zeolite of FER structural type with a purity greater than or equal to 90% by weight, preferably with a purity greater than 95% by weight, with a SiGh / AhCh ratio of between 15 and 30, inclusive, preferably between 10 and 25, inclusive, obtained by the preparation method according to any one of the preceding variants.

[0025] The invention also relates to an IZM-8 zeolite of FER structural type with a purity greater than or equal to 90% by weight, preferably with a purity greater than 95% by weight, with a SiCh / AhOs ratio of between 15 and 30, inclusive, preferably between 10 and 25, inclusive, calcined according to the protocol previously described, for which the average values ​​of the dhki and relative intensities measured on an X-ray diffraction diagram are as follows, where FF = very strong; F = strong; m = medium; mf = medium weak; f = weak; ff = very weak, the relative intensity l rei being 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 diagram: ff <15; 15 <30; 30 < mf <50; 50 <m < 65 ; 65 <F < 85 ; FF >85: Table 1

[0026] Said IZM-8 zeolite can have a micropore volume between 0.122 and 0.136 cm 3 / g and a BET specific surface area between 325 and 400 m 2 / g. DESCRIPTION OF EMBODIMENTS

[0027] The subject of the present invention is a new process for preparing an IZM-8 zeolite of structural type FER, by conversion or transformation under hydrothermal conditions of a zeolite of structural type FAU, in the presence of a specific nitrogenous or structuring organic compound, N-ethyl-N-(3,3,5-trimethylcyclohexyl) pyrrolidinium hydroxide.

[0028] In particular, the applicant has discovered that the specific nitrogenous or structuring organic compound N-ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium hydroxide, mixed with a zeolite of structural type FAU, used as a source of silicon and aluminum, in the presence or absence of an additional contribution, within said mixture of at least one source of at least one trivalent element Y chosen from aluminum, boron, or gallium, leads to the production of a mixture called precursor gel of an IZM-8 zeolite of structural type FER having a molar ratio of the total quantity expressed in oxides of tetravalent elements to the total quantity expressed in oxides of trivalent elements of between 8 and 13.The total amount of tetravalent elements represents the SiC>2 content from the FAU zeolite, the total amount of trivalent elements represents the sum of the AI2O3 content from the FAU zeolite and the Y2O3 content from the possible additional source of a Y2O3 oxide, in the case where an addition of at least one additional source of a Y2O3 oxide is made.

[0029] The ripening of the gel, then its hydrothermal treatment, then allows the production of an IZM-8 zeolite of structural type FER of high purity, even very high purity.

[0030] Any other crystallized or amorphous phase is generally and very preferentially absent from the crystallized solid consisting of the IZM-8 zeolite of structural type FER obtained at the end of the preparation process.

[0031] The purity of the IZM-8 zeolite of FER structural type obtained is greater than or equal to 90% by weight, preferably greater than or equal to 95% by weight, very preferably greater than or equal to 97%, and more preferably greater than or equal to 98%, and even more preferably greater than or equal to 99%, or even greater than or equal to 99.8% by weight relative to the total mass of crystallized solid material obtained.

[0032] Advantageously, the IZM-8 zeolite of FER structural type obtained has a SiCh / AhOs ratio of between 15 and 30, preferably between 10 and 25.

[0033] LIST OF FIGURES

[0034] Figure 1 represents the chemical formula of the organic nitrogen compound R which is the structuring agent used in the synthesis process according to the invention. Figure 2 represents the X-ray diffraction patterns of the IZM-8 zeolite of structural type FER obtained according to Example 3.

[0035] Figure 3 shows the X-ray diffraction patterns of the IZM-8 zeolite of structural type FER obtained according to Example 4.

[0036] Figure 4 shows the X-ray diffraction patterns of the MOR structural type zeolite obtained according to Example 6.

[0037] Other characteristics and advantages of the process for synthesizing IZM-8 zeolite 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.

[0038] Detailed description of the invention

[0039] The present invention more specifically relates to a new process for preparing an IZM-8 zeolite of structural type FER comprising at least the following steps: i) mixing in an aqueous medium, a zeolite of structural type FAU, a nitrogenous organic compound R, also called specific structuring agent, N-ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium hydroxide, at least one alkali metal and / or an alkaline earth metal M of valence n, n being an integer greater than or equal to 1, optionally at least one source of a trivalent element in the form of oxide Y2O3, the mixture having the following molar composition:

[0040] (SiC>2 (FAU)) / (AhO3 (FAU) + Y2O3) between 6 and 200, preferably between 6 and 100

[0041] H2O / (SiC>2 (FAU)) between 1 and 16, preferably between 5 and 14

[0042] R / (SiC>2 (FAU)) between 0.01 and 0.5, preferably between 0.04 and 0.3

[0043] M2 / nO / (SiO2(FAU)) between 0.005 and 0.45, preferably between 0.05 and 0.2 in which Y is one or more trivalent element(s) chosen from the group formed by the following elements: aluminum, boron, gallium, preferably Y is aluminum, SiC>2 (FAU) being the quantity of SiC>2 provided by the FAU zeolite, and ALO3 (FAU) being the quantity of AI2O3 provided by the FAU zeolite, 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 metals, very preferably M is sodium.until a homogeneous mixture called precursor gel is obtained; step i) preferably being carried out for a period of between 5 and 15 minutes ii) The ripening of the precursor gel of said step i) at a temperature of between 15 and 100°C with or without stirring, for a period of between 10 minutes and 48 hours, preferably between 6 and 24 hours; iii) the hydrothermal treatment of said precursor gel obtained at the end of step ii) at a temperature of between 120 and 220°C, for a period of between 12 hours and 7 days until said IZM-8 zeolite of FER structural type is formed.

[0044] An advantage of the present invention is therefore to provide a new preparation process allowing the preparation of a zeolite of structural type FER of high purity, or even of very high purity, from a zeolite of structural type FAU, said process being carried out in the presence of a specific organic structuring agent, N-ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium hydroxide.

[0045] The starting FAU structural type zeolite, preferably having a SiCh / AhCh molar ratio greater than or equal to 6.00, can be obtained by any method known to those skilled in the art such as by steaming and acid washes on a FAU structural type zeolite with a SiCh / AhCh molar ratio less than 6.00. Among the sources of FAU with a SiO2 / AhO3 ratio greater than or equal to 6.00, mention may be made of the commercial zeolites CBV712, CBV720, CBV760 and CBV780 produced by Zeolyst, the commercial zeolites HSZ-350HUA, HSZ-360HUA and HSZ-385HUA produced by TOSOH.

[0046] In a first embodiment, a zeolite of structural type FAU having a molar ratio SiO2 (FAU A^OS <FAU) supérieur ou égal à 6,00, de préférence compris entre 6,00 et 200, et de manière préférée compris entre 6,00 et 100, peut être incorporée dans le mélange réactionnel pour la mise en œuvre de l’étape (i) comme source d’élément silicium et aluminium.

[0047] In another embodiment, a zeolite of structural type FAU and at least one other source of a trivalent element in oxide form Y2O3 can be used in step i), the composition of the reaction mixture is such that (SiC>2 (FAU)) / (AhO3 <FAU) + Y2O3) soit compris entre 6 et 200, de préférence entre 6 et 100.

[0048] In a preferred variant of this embodiment, when Y is aluminum, and a zeolite of structural type FAU and at least one other source of aluminum in oxide form AI2O3 are used in step i), the composition of the reaction mixture is such that (Si O2 (FAU)) / (AhO3 (FAU) + AI2O3) is between 6 and 200, preferably between 6 and 100, which means that the amount of aluminum oxide provided by the zeolite FAU and the amount of aluminum oxide provided by the other source of aluminum are taken into account in the composition of the reaction mixture.

[0049] According to the invention, R is the organic nitrogen compound N-ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium hydroxide, said compound being incorporated into the reaction mixture for the implementation of step (i), as an organic structuring agent.

[0050] 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 to 1, M preferably being chosen from lithium, potassium, sodium, magnesium and calcium and the mixture of at least two of these metals. Very preferably, M may be sodium.

[0051] Preferably, the source of at least one alkali and / or alkaline earth metal M may be sodium hydroxide.

[0052] According to the invention, at least one additional source of an oxide Y2O3, Y being one or more trivalent element(s) chosen from the group formed by the following elements: aluminum, boron, gallium, can be used in the mixture of step i). Preferably, Y can be aluminum.

[0053] The aluminum source may preferably be aluminum hydroxide or an aluminum salt, for example chloride, nitrate, or sulfate, sodium aluminate, aluminum alkoxide, or alumina itself, preferably in hydrated or hydratable form, such as colloidal alumina, pseudoboehmite, gamma alumina, or alpha or beta trihydrate. Mixtures of the above-mentioned sources may also be used. Most preferably, the additional source of a Y2O3 oxide is sodium aluminate.

[0054] Step (i) of the process according to the invention consists in preparing an aqueous reaction mixture containing a zeolite of structural type FAU, optionally a source of an oxide Y2O3, at least one organic nitrogen compound R, R being N-ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium hydroxide, 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 FER. The quantities of said reagents in the reaction mixture are adjusted as indicated previously so as to give this gel a composition allowing the crystallization of an IZM-8 zeolite of structural type FER.

[0055] It may be advantageous to add seeds of a zeolite of structural type FER to the reaction mixture during said step i) or to the precursor gel during said step ii) of the process of the invention, preferably at the end of the ripening step ii), in order to reduce the time required for the formation of crystals of a zeolite of structural type FER and / or the total crystallization time. Said crystal seeds also promote the formation of said IZM-8 zeolite of structural type FER to the detriment of impurities. Such seeds comprise crystallized solids, in particular crystals of a zeolite of structural type FER.The crystal seeds are generally added in a proportion of between 0.01 and 10% of the total mass of the sources of said tetravalent and trivalent element(s) used in the reaction mixture, said crystal seeds not being taken into account in the total mass of the sources of the tetravalent and trivalent elements. Said seeds are not taken into account in determining the composition of the reaction mixture and / or the gel, defined further, i.e. in determining the various molar ratios, in particular (SiO2 (FAU)) / (AhO3 (FAU) + Y2O3), H2O / (SiO2 (FAU)), R / (SiO2 (FAU)), M2 / nO / (SiO2 (FAU)), of the composition of the reaction mixture.

[0056] Step i) of mixing is carried out until a homogeneous mixture is obtained, preferably for a period of between 5 and 15 minutes, preferably with stirring by any system known to those skilled in the art with low or high shear rate.

[0057] At the end of step i), a homogeneous precursor gel is obtained.

[0058] Step ii) of ripening the reaction mixture before hydrothermal crystallization during said step iii) of the process of the invention makes it possible to control the size of the crystals of an IZM-8 zeolite of FER structural type. Said ripening also promotes the formation of said zeolite of FER structural type to the detriment of impurities. The ripening of the reaction mixture during said step ii) of the process of the invention can be carried out at room temperature (generally considered to be equal to 20°C) or at a temperature between 15 and 100°C with or without stirring, for a period of between 10 min and 48 hours, preferably between 6 and 24 hours.

[0059] In accordance with step (ii) of the process according to the invention, the precursor gel obtained at the end of step ii) is subjected to a hydrothermal treatment carried out at a temperature of between 120 and 220°C for a period of between 12 hours and 7 days, until said IZM-8 zeolite of structural type FER is formed.

[0060] The precursor gel is advantageously placed under hydrothermal conditions under autogenous reaction pressure, optionally by adding gas, for example nitrogen, at a temperature preferably between 120 and 220°C, preferably between 140 and 195°C, until complete crystallization of an IZM-8 zeolite of FER structural type.

[0061] The time required to obtain crystallization varies between 12 hours and 7 days, preferably between 12 hours and 6 days, more preferably between 12 hours and 3 days.

[0062] The reaction is generally carried out with or without stirring, preferably with stirring. Any stirring system known to those skilled in the art can be used as the stirring system, for example, inclined blades with counterblades, stirring turbines, Archimedes screws.

[0063] At the end of the reaction, after carrying out said step iii) of the preparation process according to the invention, the solid phase formed from an IZM-8 zeolite of FER structural type can preferably be filtered, washed and then dried. Drying can generally be carried out at a temperature between 20 and 120°C, preferably between 60 and 100°C, for a period of between 5 and 24 hours.

[0064] The dried zeolite can then be advantageously calcined. The calcined IZM-8 zeolite of structural type FER 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.

[0065] Very advantageously, the process of the invention leads to the formation of a zeolite of structural type FER, free from any other crystallized or amorphous phase. Said IZM-8 zeolite of structural type FER, after the drying step, is then ready for subsequent steps such as calcination and ion exchange. For these steps, all conventional methods known to those skilled in the art can be used.

[0066] The loss on ignition of said IZM-8 zeolite of FER structural type obtained after drying and before calcination is generally between 5 and 15% by weight. According to the invention, loss on ignition (LAI) means the percentage loss of mass undergone by a solid compound, in the case of the present invention by said prepared IZM-8 zeolite, during a heat treatment at 1000°C for 2 hours, in a muffle furnace type furnace, relative to the mass of the initial solid compound, preferably in the case of the present invention relative to the mass of dried IZM-8 zeolite. Loss on ignition generally corresponds to the loss of solvent (such as water), but also to the elimination of organic compounds contained in the solids.

[0067] The IZM-8 zeolite of FER structure type obtained according to the process of the invention can advantageously be calcined. The calcination step can preferably be carried out at a temperature between 450 and 700°C for a duration between 2 and 20 hours.

[0068] The IZM-8 zeolite of structural type FER obtained at the end of the calcination stage is devoid of any organic species and in particular of the organic structuring agent R.

[0069] At the end of said calcination step, X-ray diffraction makes it possible to verify that the solid obtained by the process according to the invention is indeed a zeolite of FER structural type. The purity of the IZM-8 zeolite of FER structural type obtained is thus greater than or equal to 90% by weight, preferably greater than or equal to 95% by weight, very preferably greater than or equal to 97%, more preferably greater than or equal to 98%, and even more preferably greater than or equal to 99%, or even greater than or equal to 99.8% by weight relative to the total mass of crystallized solid material obtained.

[0070] The solid obtained has the X-ray diffraction pattern including at least the lines listed in Table 1. Preferably, the X-ray diffraction pattern does not contain any other lines of significant intensity (i.e. intensity greater than about three times the background noise) than those listed in Table 1.

[0071] This diffraction pattern is obtained by X-ray crystallographic analysis using a diffractometer 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 d h ki 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. The relative intensity l reiassigned to each dhki value is measured from the height of the corresponding diffraction peak. The X-ray diffraction pattern of the crystalline solid of structural type FER according to the invention comprises at least the lines with the dhki values ​​given in Table 1, which presents the average values ​​of the dhki and relative intensities measured on an X-ray diffraction pattern of the calcined crystalline solid of structural type FER. In the dhki column, the average values ​​of the inter-reticular distances in Angstroms (Â) are indicated. Each of these values ​​must be assigned the measurement error A(d h ki) between ± 0.6Â and ± 0.01Â.

[0072] Table 1 where FF = very strong; F = strong; m = medium; mf = medium weak; f = weak; ff = very weak. The relative intensity l reiis 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.

[0073] 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.

[0074] The specific surface area is calculated using the Brunauer, Emmett and Teller method (BET method) (Bruanauer, S. et al. Journal of the American Chemical Society 1938, 60 (2), 309-319) and the micropore volume is calculated using the t-plot (Storck et al. Applied Catalysis A: General 1998, 174 (1-2), 137-146). The micropore volume of the calcined IZM-8 zeolite according to the invention is advantageously between 0.122 and 0.136 cm 3 / g and the BET specific surface area is advantageously between 325 and 400 m 2 / g.

[0075] It is also advantageous to obtain the protonated form of the IZM-8 zeolite of structural type FER obtained by the process according to the invention. Said protonated 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 ammonium chloride, sulfate or nitrate. The ion exchange can be carried out by suspending said IZM-8 zeolite of structural type FER in one or more times with the ion exchange solution. Said zeolite can be calcined before or after the ion exchange, or between two ion exchange steps. The zeolite is preferably calcined before the ion exchange, in order to eliminate any organic substance included in the porosity of the zeolite, since the ion exchange is thereby facilitated.

[0076] The IZM-8 zeolite of FER structure type obtained by the process of the invention can be used after ion exchange as an acidic solid for catalysis in the fields of refining and petrochemistry. It can also be used as an adsorbent or as a molecular sieve.

[0077] EXAMPLES

[0078] Example 1: preparation of N-ethyl-N-(3,3,5-trimethylcyclohexyl) pyrrolidinium dihydroxide (structuring agent R).

[0079] 42.1 g (0.3 M) of 3,3,5-trimethyl-Cyclohexanone and 64 g (0.9 M) of pyrrolidine are loaded into a 1000 ml flask and then 500 ml of cyclohexane are added to dissolve the reagents. The reaction medium is stirred at 450 rpm and then 65 g (0.54 M) of magnesium sulfate are added. The reaction medium is heated to reflux for 120 h. After returning to room temperature, the suspension obtained is filtered on a porosity 3 frit. The solid obtained is washed on the frit with 2 times 50 ml of cyclohexane. After removal of the cyclohexane in a rotary evaporator, 54 g (with a yield of 93%) of product are obtained. NMR spectra 1 H and 13 C are consistent with the structure of the expected product (in particular, ethylenic protons of the enamine at 4.05 and 4.11 ppm, ethylenic carbons at 99.62, 105.62, 141.36 and 142.11 ppm). of the N-(3,3,5-tri

[0080] 25.1 g (0.13 M) of enamine are loaded into a 100 ml flask and then 13 g (0.282 M) of formic acid are added while stirring at 300 rpm. The reaction medium is then heated to 80°C for 3 hours. After returning to room temperature, 20 g of 10% hhSCU are added while stirring at 800 rpm and the reaction medium is kept stirring at room temperature overnight.

[0081] 50 g of 20% NaOH and 150 ml of ethyl ether are added to produce a two-phase medium whose aqueous phase has a pH > 10. The organic phase is decanted and then the aqueous phase is extracted with 2 times 100 ml of ethyl ether. The organic phases are combined and then dried over magnesium sulfate. After filtration of the magnesium sulfate and removal of the ethyl ether in a rotary evaporator, 22.9 g (Yield: 90%) of product are obtained. NMR spectra 1 H and 13C are consistent with the structure of the expected product (in particular, disappearance of ethylenic protons and ethylenic carbons, protons in p of nitrogen at 2.29, 2.48 and 2.61 ppm).

[0082] 19.5 g (0.1 M) of N-(3,3,5-trimethylcyclohexyl) pyrrolidine are loaded into a 500 ml flask and then 250 ml of acetonitrile are added to dissolve the N-(3,3,5-trimethylcyclohexyl) pyrrolidine. The reaction medium is heated to 60°C with stirring at 200 rpm (magnetic bar) and then 62.3 g (0.4 M) of ethyl iodide are added over 22 min. The reaction medium is maintained at 60°C for 24 h.

[0083] After evaporation of the acetonitrile, 34.9 g (crude yield 99.5%) of crude product are obtained.

[0084] This solid is taken up in 290 ml of acetone. After heating to reflux to obtain a solution, 140 ml of ethyl ether are added and the precipitation of a white solid is observed. After returning to room temperature, the suspension obtained is filtered on a porosity 3 frit. The solid obtained is washed on the frit with 100 ml of a 1 / 2 ethyl ether / acetone mixture.

[0085] 29 g of wet solid are thus obtained. The solid is then dried to constant weight overnight in a ventilated oven at 45°C. 23.7 g (Yield 68%) of product are obtained.

[0086] Due to the presence of two diastereoisomers, the NMR spectra 1 H and 13 C are complex, but consistent with the structure of the expected product (p-protons of nitrogen at 3.38 and 3.58 ppm). The product appears to be of very high purity and no signals are observed that could correspond to the presence of impurities.

[0087] Synthesis of N-ethyl-N-(3,3,5-trimethylcyclohexyl) pyrrolidinium hydroxide

[0088] 18.8 g of Ag2O (0.08 mol, 99%, Aldrich) are added to a 250 mL Teflon beaker containing 23.4 g of N-ethyl-N-(3,3,5-trimethylcyclohexyl) pyrrolidinium iodide (0.07 mol) and 183 mL of deionized water. The reaction medium is stirred away from light for 12 hours. The mixture is then filtered. The filtrate obtained is composed of an aqueous solution of N-ethyl-N-(3,3,5-trimethylcyclohexyl) pyrrolidinium hydroxide. The determination of this species is carried out by proton NMR.

[0089] Example 2: preparation of an IZM-8 zeolite of structural type FER

[0090] 5.26 g of deionized water were mixed with 0.43 g of sodium hydroxide (99.5% by weight, Aldrich). 2.36 g of a zeolite of structural type FAU (CBV720, SiO2 / Al2C>3=34.7, Zeolyst, PAF = 8.54%) were added to the previous mixture, the preparation obtained was kept stirring for 15 minutes. 2.65 g of an aqueous solution of N-ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium hydroxide (21.68% by weight) prepared according to Example 1 were added to the synthesis mixture and kept stirring for 10 minutes. The synthesis mixture was kept stirring for 24 hours. The molar composition of the mixture is as follows: 1 SiCh: 0.03 AI2O3: 0.074 R: 0.165 Na2O: 13.4 H2O, i.e. a SiCh / AhCh ratio of 33. The precursor gel is then transferred, after homogenization, into an autoclave. The autoclave is closed and then heated for 6 days at 150°C with stirring at 35 rpm using a rotating spit system.The crystallized product obtained is filtered, washed with deionized water and then dried overnight at 100°C. 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.

[0091] The calcined solid product was analyzed by X-ray diffraction and identified as consisting of an IZM-8 zeolite of structural type FER with a purity equal to 91% by weight. The product has a SiCh / AhOs molar ratio of 19 as determined by X-ray fluorescence. The BET surface area and micropore volume are 345 m 2 / g and 0.122 cm 3 / g respectively.

[0092] Example 3: Preparation of an IZM-8 zeolite of structural type FER

[0093] 4.29 g of deionized water were mixed with 0.33 g of sodium hydroxide (99.5% by weight, Aldrich). 2.17 g of a zeolite of structural type FAU (CBV780, SiO2 / AhO3=96.2, Zeolyst, PAF = 14%) were added to the previous mixture, the preparation obtained was kept stirring for 15 minutes. 3.23 g of an aqueous solution of N-ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium hydroxide (26.2% by weight) prepared according to Example 1 were added to the synthesis mixture and kept stirring for 10 minutes. Subsequently, 0.11 g of sodium aluminate (NaAIC>2, 53% by mass of AI2O3, Carlo Erba), are incorporated into the synthesis mixture, which is kept stirring for 24 hours. The molar composition of the mixture is as follows: 1 SiO2: 0.031 AI2O3: 0.12 R: 0.165 Na2O: 13.6 H2O, i.e. a SiCh / AhCh ratio of 33. The precursor gel is then transferred, after homogenization, into an autoclave.The autoclave is closed and then heated for 6 days at 150°C with stirring at 35 rpm with a rotating spit system. The crystallized product obtained is filtered, washed with deionized water and then dried overnight at 100°C. 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.

[0094] The calcined solid product was analyzed by X-ray diffraction and identified as consisting of an IZM-8 zeolite of structural type FER, with a purity equal to 91% by weight. The diffraction pattern performed on this solid is given in Figure 2. The product has a SiCh / AhCh molar ratio of 19.5 as determined by X-ray fluorescence. The BET surface area and micropore volume are 350 m 2 / g and 0.120 cm 3 / g respectively.

[0095] Example 4: Preparation of an IZM-8 zeolite of structural type FER with addition of seeds

[0096] 4.26 g of deionized water were mixed with 0.33 g of sodium hydroxide (99.5% by weight, Aldrich). 2.14 g of a zeolite of structural type FAU (CBV780, SiO2 / AI2O3=96.2, Zeolyst, PAF = 14%) were added to the previous mixture, the preparation obtained was kept stirring for 15 minutes. 3.18 g of an aqueous solution of N-ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium hydroxide (26.2% by weight) prepared according to Example 1 were added to the synthesis mixture and kept stirring for 10 minutes. Subsequently, 0.10 g of sodium aluminate (NaAlCh, 53% by mass of AI2O3, Carlo Erba), are incorporated into the synthesis mixture, which is kept stirring for 24 hours. The molar composition of the mixture is as follows: 1 SiCh: 0.03 AI2O3: 0.12 R: 0.168 Na2O: 13.6 H2O, i.e. a SiCh / AhCh ratio of 33. To this mixture are added seeds of a FER type zeolite (0.17 g of FER zeolite with a SiCh / AhCh molar ratio of 9.9).The precursor gel is then transferred, after homogenization, into an autoclave. The autoclave is closed and then heated for 3 days at 150°C with stirring at 35 rpm with a rotating spit system. The crystallized product obtained is filtered, washed with deionized water and then dried overnight at 100°C. 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.

[0097] The calcined solid product was analyzed by X-ray diffraction and identified as consisting of an IZM-8 zeolite of structural type FER (ICDD sheet, PDF 01-073-9977), with a purity greater than 99% by weight. The diffraction pattern performed on this solid is given in Figure 3. The product has a SiC^ / AhCh molar ratio of 15.8 as determined by X-ray fluorescence. The BET surface area and micropore volume are 364 m 2 / g and 0.128 cm 3 / g respectively.

[0098] Example 5: Preparation of an IZM-8 zeolite of structural type FER with addition of seeds

[0099] 4.26 g of deionized water were mixed with 0.33 g of sodium hydroxide (99.5% by weight, Aldrich). 2.14 g of a zeolite of structural type FAU (CBV780, SiO2 / AhO3=96.2, Zeolyst, PAF = 14%) were added to the previous mixture, the preparation obtained was kept stirring for 15 minutes. 3.18 g of an aqueous solution of N-ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium hydroxide (26.2% by weight) prepared according to Example 1 were added to the synthesis mixture and kept stirring for 10 minutes. Subsequently, 0.10 g of sodium aluminate (NaAlCh, 53% by mass of AI2O3, Carlo Erba), are incorporated into the synthesis mixture, which is kept stirring for 24 hours. The molar composition of the mixture is as follows: 1 SiO2: 0.03 AI2O3: 0.12 R: 0.168 Na2O: 13.6 H2O, i.e. a SiC^ / AhOs ratio of 33. To this mixture are added seeds of a FER type zeolite (0.087 g of FER zeolite with a SiC^ / AfeOs molar ratio of 9.9).The precursor gel is then transferred, after homogenization, into an autoclave. The autoclave is closed and then heated for 3 days at 150°C with stirring at 35 rpm with a rotating spit system. The crystallized product obtained is filtered, washed with deionized water and then dried overnight at 100°C. 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.

[0100] The calcined solid product was analyzed by X-ray diffraction and identified as consisting of an IZM-8 zeolite of structural type FER (ICDD sheet, PDF 01-073-9977), with a purity greater than 99% by weight. The BET surface area and micropore volume are 360 ​​m 2 / g and 0.125 cm 3 / g respectively.

[0101] Example 6: Synthesis not in accordance with the invention

[0102] 6.6 g of deionized water were mixed with 0.297 g of sodium hydroxide (99.5% by weight, Aldrich). 2.36 g of a zeolite of structural type FAU (CBV720, SiO2 / AhO3=34.7, Zeolyst, PAF = 8.54%) were added to the previous mixture, the preparation obtained was kept stirring for 15 minutes. 1.52 g of an aqueous solution of N-ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium hydroxide (26.20% by weight) prepared according to Example 1 were added to the synthesis mixture and kept stirring for 10 minutes. The mixture was kept stirring for 24 hours. The molar composition of the mixture is as follows: 1 SiCh: 0.03 AI2O3: 0.074 R: 0.165 Na2O: 20 H2O, i.e. a SiCh / AhOs ratio of 33. The precursor gel is then transferred, after homogenization, into an autoclave. The autoclave is closed and then heated for 6 days at 150°C with stirring at 35 rpm using a rotating spit system.The crystallized product obtained is filtered, washed with deionized water and then dried overnight at 100°C. 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.

[0103] The calcined solid product was analyzed by X-ray diffraction and identified as consisting of a MOR structural type zeolite (ICDD file, PDF 04-023-4678), with a purity greater than 99% by weight.

Claims

CLAIMS 1. Process for the preparation of a high-purity IZM-8 zeolite of FER structure type comprising at least the following steps: i) mixing in an aqueous medium, a zeolite of FAU structure type as a source of silicon in the form of SiC>2 oxide and aluminum in the form of AI2O3 oxide, an organic nitrogen compound R, R being N-ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium hydroxide, at least one alkali metal and / or an alkaline-earth metal M of valence n, n being an integer greater than or equal to 1, and optionally at least one source of a trivalent element in the form of Y2O3 oxide, the mixture having the following molar composition: (SiC>2 (FAU)) / (AhO3 (FAU) + Y2O3) between 6 and 200, preferably between 6 and 100 H2O / (SiC>2 (FAU)) between 1 and 16, preferably between 5 and 14 R / (SiC>2 (FAU)) between 0.01 and 0.5, preferably between 0.04 and 0.3 M2 / nO / (SiO2(FAU)) between 0.005 and 0.45, preferably between 0.05 and 0.2 in which Y is one or more trivalent element(s) chosen from the group formed by the following elements: aluminum, boron, gallium, SiC>2 (FAU) being the quantity of SiC>2 provided by the FAU zeolite, and AI2O3 (FAU) being the quantity of AI2O3 provided by the FAU zeolite, 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 metals, until a homogeneous precursor gel is obtained; ii) maturing the homogeneous precursor gel obtained at the end of said step i) at a temperature between 15 and 100°C, with or without stirring, for a period between 10 minutes and 48 hours;iii) hydrothermal treatment of said precursor gel obtained at the end of step ii) at a temperature of between 120 and 220°C for a period of between 12 hours and 7 days, inclusive, until said IZM-8 zeolite of structural type FER is formed.; 2. Method according to claim 1 in which M is sodium, preferably the source of at least one alkali metal M is sodium hydroxide.

3. Method according to one of the preceding claims in which Y is aluminum.

4. Method according to one of the preceding claims, in which crystalline seeds of a zeolite of structural type FER are added to the reaction mixture of step i) or to the homogeneous precursor gel of step ii), in an amount of between 0.01 and 10% of the total mass of the sources of said element(s) Si and Al in anhydrous form used in the mixture. reactive, said crystalline germs not being taken into account in the total mass of the sources of the elements Si and Al.

5. Process according to one of the preceding claims, in which the ripening of step ii) is carried out with stirring at room temperature for a period of between 6 and 24 hours, inclusive.

6. Method according to one of the preceding claims in which the hydrothermal treatment of step iii) is carried out under autogenous reaction pressure.

7. Method according to one of the preceding claims in which the hydrothermal treatment of step iii) is carried out at a temperature between 140 and 195°C.

8. Method according to one of the preceding claims in which, after carrying out said step iii), the solid phase formed from an IZM-8 zeolite of FER structural type obtained at the end of step iii) 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.

9. Method according to claim 8 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.

10. Zeolite IZM-8 of structural type FER with a purity greater than or equal to 90% by weight, preferably with a purity greater than 95% by weight, with a SiCh / AhOs ratio of between 15 and 30, inclusive, preferably between 10 and 25, inclusive, obtained by the preparation process according to one of claims 1 to 9.

11. Zeolite IZM-8 of structural type FER of purity greater than or equal to 90% by weight, preferably of purity greater than 95% by weight, of SiCh / AhOs ratio between 15 and 30, limits included, preferably between 10 and 25, limits included, obtained by the preparation process according to claim 9 for which the average values ​​of the dhki and relative intensities measured on an X-ray diffraction diagram are as follows, where FF = very strong; F = strong; m = medium; mf = medium weak; f = weak; ff = very weak, the relative intensity Irei 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 <30; 30 < mf <50; 50 <m < 65 ; 65 <F < 85 ; FF >85: Table 1 12. Zeolite IZM-8 of structural type FER according to claim 11 having a microporous volume of between 0.122 and 0.136 cm 3 / g and a BET specific surface area between 325 and 400 m 2 / g.

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