Synthesis of high purity FER framework type IZM-8 zeolite

Abstract

The present invention relates to a novel process for preparing an FER framework type IZM-8 zeolite which can synthesize an FER framework type IZM-8 zeolite by converting / transforming an FAU framework type zeolite under hydrothermal conditions. Specifically, the new method makes it possible to synthesize FER framework type IZM-8 zeolites starting from FAU framework type zeolites used as sources of silicon and aluminum and specific organic or structured molecule N-ethyl-N-(3, 3, 5-trimethylcyclohexyl) pyrrolidinium hydroxides comprising quaternary ammonium functions. The FER framework type IZM-8 zeolite obtained according to the process of the invention is advantageously used as a catalyst, adsorbent or separating agent.

Description

Technical Field

[0001] The present invention relates to a new method for preparing FER framework type IZM-8 zeolite. This new method can synthesize FER framework type IZM-8 zeolite by converting FAU framework type zeolite under hydrothermal conditions. Specifically, the new method enables the synthesis of FER framework type IZM-8 zeolite starting from FAU framework type zeolite used as a silicon source and an aluminum source and a specific structured or organic molecule N-ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium hydroxide containing a quaternary ammonium functional group. The FER framework type IZM-8 zeolite obtained according to the method of the present invention is advantageously used as a catalyst, adsorbent or separator. Background Art

[0002] Crystalline microporous materials (such as zeolites or silicoaluminophosphates) are solids widely used as catalysts, catalytic carriers, adsorbents or separators in the petroleum industry. Although many microporous crystal structures have been discovered, the refining and petrochemical industries have been searching for new zeolite structures that have specific properties for applications such as gas purification or separation, conversion of carbon-based substances, etc.

[0003] The FER framework type includes the following zeolites: ZSM-35, NU-23, FU-9, ISI-6. The FER framework type has a two-dimensional 10-MR channel system with a pore size of 0.42 x 0.54 nm, which is interconnected by an 8-MR channel system 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).

[0004] FER framework type zeolites are synthesized using nitrogen-containing organic substances such as pyrrolidine (J. Pérez-Pariente et al., Micropor. Mesopor. Mat., 129, (2010) 164; L.Y. 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).

[0005] V. Valtchev et al. (Micropor. Mesopor. Mat., 200, (2014) 334) prepared FER framework zeolites in the presence of Na ethylenediamine, Na-K, and Na pyrrolidine to study the effect of the mixture of two structuring agents on the crystallization time and morphology of the obtained materials.

[0006] The use of tetrahydrofuran organic compounds as structuring agents for the preparation of FER framework zeolites can also be mentioned (Y-C Long et al., Chem. Commun, 19, (2000), 1893; Y.C. Long et al., Micropor. Mesopor. Mat., 119, (2009) 60).

[0007] J. Pérez-Pariente et al. (Chem. Mater., 19, 23 (2007), 5617; Catal. Today, 179 (2012) 16) prepared FER framework zeolites in a fluorinated medium using a mixture of tetramethylammonium and benzylmethylpyrrolidinium organic cations as structure haul agents in the absence of inorganic cations. Summary of the Invention

[0008] Surprisingly, the applicant has developed a method for preparing FER framework zeolites from FAU framework zeolites in the presence of a specific structuring agent, enabling the simple and reproducible obtaining of high-purity or even very high-purity FER framework zeolites with an SiO2 / Al2O3 ratio of 15 to 30, preferably 10 to 25, designated as IZM-8. The method for preparing FER framework IZM-8 zeolites can synthesize FER framework IZM-8 zeolites by converting / transforming FAU framework zeolites under hydrothermal conditions. Specifically, the new method enables the synthesis of FER framework IZM-8 zeolites starting from FAU framework zeolites used as a silicon source and an aluminum source and a specific organic or structure molecule N-ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium hydroxide containing a quaternary ammonium functional group. The FER framework IZM-8 zeolites obtained according to the method of the present invention are advantageously used as catalysts, adsorbents, or separation agents.

[0009] More specifically, the present invention relates to a method for preparing high-purity FER framework IZM-8 zeolites, the method comprising at least the following steps:

[0010] i) Mix in an aqueous medium a FAU framework type zeolite as a silicon source in the form of SiO2 and an aluminum source in the form of Al2O3, a nitrogen-containing organic compound R, at least one alkali metal and / or alkaline earth metal M of valence n, and optionally a trivalent element source in the form of at least one Y2O3, until a homogeneous precursor gel is obtained, where R is N-ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium hydroxide, n is an integer greater than or equal to 1, and the mixture has the following molar composition:

[0011] (SiO 2(FAU) ) / (Al2O 3(FAU) +Y2O3) is from 6 to 200, preferably from 6 to 100,

[0012] H2O / (SiO 2(FAU) ) is from 1 to 16, preferably from 5 to 14,

[0013] R / (SiO 2(FAU) ) is from 0.01 to 0.5, preferably from 0.04 to 0.3,

[0014] M 2 / n O / (SiO 2(FAU) ) is from 0.005 to 0.45, preferably from 0.05 to 0.2,

[0015] where Y is one or more trivalent elements selected from the following elements: aluminum, boron, gallium, SiO 2(FAU) is the amount of SiO2 provided by the FAU zeolite, and Al2O 3(FAU) is the amount of Al2O3 provided by the FAU zeolite, and M is one or more alkali metals and / or alkaline earth metals selected from lithium, sodium, potassium, calcium, magnesium, and mixtures of at least two of these metals;

[0016] ii) At a temperature of 15 °C to 100 °C, with or without stirring, let the homogeneous precursor gel obtained at the end of step i) cure for 10 minutes to 48 hours;

[0017] iii) At a temperature of 120 °C to 220 °C, subject the precursor gel obtained at the end of step ii) to hydrothermal treatment for 12 hours to 7 days (including the end values) until a FER framework type IZM-8 zeolite is formed.

[0018] Preferably, M is sodium.

[0019] Preferably, the source of at least one alkali metal M is sodium hydroxide.

[0020] Y can be aluminum.

[0021] The seeds of FER framework zeolite can be added to the reaction mixture in step i) or the homogeneous precursor gel in step ii) in an amount of 0.01-10% of the total mass of the sources of the Si and Al elements in anhydrous form used in the reaction mixture, and the seeds are not included in the total mass of the sources of the Si and Al elements. The aging in step ii) can be carried out with stirring at ambient temperature for 6 to 24 hours (including the end values).

[0022] The hydrothermal treatment in step iii) is carried out under autogenous reaction pressure.

[0023] The hydrothermal treatment in step iii) can be carried out at a temperature of 140 °C to 195 °C.

[0024] After step iii) is carried out, the solid phase formed by FER framework zeolite obtained at the end of step iii) is filtered out, washed, and dried at a temperature of 20 °C to 150 °C, preferably 60 °C to 100 °C, for 5 to 24 hours to obtain the dried zeolite.

[0025] The dried zeolite can then be calcined at a temperature of 450 °C to 700 °C for 2 to 20 hours, and the calcination can be carried out by gradually increasing the temperature.

[0026] The present invention also relates to an IZM-8 zeolite with an FER framework obtained by the preparation method described in any one of the foregoing variants, having a purity greater than or equal to 90% by weight, preferably greater than 95% by weight, and an SiO2 / Al2O3 ratio of 15 to 30 (including the end values), preferably 10 to 25 (including the end values).

[0027] The present invention also relates to an IZM-8 zeolite with an FER framework calcined by the foregoing scheme, having a purity greater than or equal to 90% by weight, preferably greater than 95% by weight, and an SiO2 / Al2O3 ratio of 15 to 30 (including the end values), preferably 10 to 25 (including the end values), wherein the d measured on the X-ray diffraction pattern hkl and the average relative intensity are as follows: VS = very strong; S = strong; m = medium; mw = medium-weak; w = weak; vw = very weak, and the relative intensity I rel is given relative to a relative intensity scale, with the strongest line in the X-ray diffraction pattern taken as 100:

[0028] vw < 15; 15 ≤ 30; 30 ≤ mw < 50; 50 ≤ m < 65; 65 ≤ S < 85; VS ≥ 85:

[0029] Table 1

[0030]

[0031] The micropore volume of the IZM-8 zeolite can be 0.122 to 0.136 cm3 / g, the BET specific surface area is 325 to 400 m 2 / g. Detailed implementation mode

[0032] The subject of the present invention is a new method for preparing FER framework type IZM-8 zeolite. The method involves converting or transforming FAU framework type zeolite under hydrothermal conditions in the presence of a specific structured or nitrogen-containing organic compound, N-ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium hydroxide.

[0033] Specifically, the applicant has found that mixing the specific structured or nitrogen-containing organic compound N-ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium hydroxide with FAU framework type zeolite (used as a source of silicon and aluminum), in the mixture, with or without the additional contribution of at least one source of at least one trivalent element Y selected from aluminum, boron, or gallium, results in the formation of a mixture called the precursor gel of FER framework type IZM-8 zeolite. The molar ratio of the total amount of tetravalent element oxides to the total amount of trivalent element oxides in this mixture is 8 to 13. The total amount of tetravalent elements represents the SiO2 content derived from the FAU zeolite. In the case of adding at least one additional source of oxide Y2O3, the total amount of trivalent elements represents the sum of the Al2O3 content derived from the FAU zeolite and the Y2O3 content derived from any other source of oxide Y2O3.

[0034] The gel is aged and then subjected to hydrothermal treatment, and subsequently, high-purity or even very high-purity FER framework type IZM-8 zeolite can be produced.

[0035] The crystalline solid composed of FER framework type IZM-8 zeolite obtained at the end of the preparation process generally and very preferably does not contain any other crystalline phase or amorphous phase.

[0036] Relative to the total mass of the obtained crystalline solid material, the purity of the obtained FER framework type IZM-8 zeolite is greater than or equal to 90% by weight, preferably greater than or equal to 95% by weight, very preferably greater than or greater than 97%, more preferably greater than or less than 98%, even more preferably greater than or equal to 99%, or even greater than or equal to 99.8% by weight.

[0037] Advantageously, the SiO2 / Al2O3 ratio of the obtained FER framework type IZM-8 zeolite is 15 to 30, preferably 10 to 25. Description of the drawings

[0038] Figure 1 Shows the chemical formula of the organic nitrogen-containing compound R, which is the structured reagent used in the synthesis method of the present invention.

[0039] Figure 2 Shows the X-ray diffraction pattern of the FER framework type IZM-8 zeolite obtained according to Example 3.

[0040] Figure 3 Shows the X-ray diffraction pattern of the FER framework type IZM-8 zeolite obtained according to Example 4.

[0041] Figure 4 Shows the X-ray diffraction pattern of the MOR framework type zeolite obtained according to Example 6.

[0042] Referring to the accompanying drawings described below, after reading the description of the following non-limiting exemplary embodiments, other features and advantages of the method for synthesizing IZM-8 zeolite according to the present invention, the catalyst according to the present invention, and the use according to the present invention will become apparent. Detailed Description

[0044] More precisely, one object of the present invention is a new method for preparing a FER framework type IZM-8 zeolite, the method comprising at least the following steps:

[0045] i) Mixing in an aqueous medium a FAU framework type zeolite, a nitrogen-containing organic compound R (also called a specific structuring agent) N-ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium hydroxide, at least one n-valent alkali metal and / or alkaline earth metal M, and optionally a source of a trivalent element in the form of at least one oxide Y2O3 until a homogeneous mixture called a precursor gel is obtained, where n is an integer greater than or equal to 1, and the mixture has the following molar composition:

[0046] (SiO 2(FAU) ) / (Al2O 3(FAU) +Y2O3) is from 6 to 200, preferably from 6 to 100,

[0047] H2O / (SiO 2(FAU) ) is from 1 to 16, preferably from 5 to 14,

[0048] R / (SiO 2(FAU) ) is from 0.01 to 0.5, preferably from 0.04 to 0.3,

[0049] M 2 / n O / (SiO 2(FAU) ) is from 0.005 to 0.45, preferably from 0.05 to 0.2,

[0050] where Y is one or more trivalent elements selected from the following elements: aluminum, boron, gallium; preferably, Y is aluminum; SiO 2(FAU) is the amount of SiO2 provided by the FAU zeolite, and Al2O 3(FAU)is the amount of Al2O3 provided by the FAU zeolite, and M is one or more alkali metals and / or alkaline earth metals selected from lithium, sodium, potassium, calcium, magnesium, and mixtures of at least two of these metals; very preferably, M is sodium.

[0051] Step i) is preferably carried out for 5 to 15 minutes;

[0052] ii) At a temperature of 15 °C to 100 °C, with or without stirring, the precursor gel of step i) is aged for 10 minutes to 48 hours, preferably 6 hours to 24 hours;

[0053] iii) At a temperature of 120 °C to 220 °C, the precursor gel obtained at the end of step ii) is hydrothermally treated for 12 hours to 7 days until the formation of FER framework type IZM-8 zeolite.

[0054] Therefore, an advantage of the present invention is that it provides a new preparation method capable of forming high-purity or even very high-purity FER framework type zeolite from FAU framework type zeolite, and the method is carried out in the presence of a specific organic structure-directing agent, N-ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium hydroxide.

[0055] The starting FAU framework type zeolite, preferably with a SiO2 / Al2O3 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 steam treatment (steaming) and pickling on FAU framework type zeolite with a SiO2 / Al2O3 molar ratio less than 6.00. As sources of FAU with a SiO2 / Al2O3 ratio greater than or equal to 6.00, commercially available zeolites CBV712, CBV720, CBV760, and CBV780 produced by Zeolyst International, and commercially available zeolites HSZ-350HUA, HSZ-360HUA, and HSZ-385HUA produced by Tosoh Corporation can be mentioned.

[0056] In the first embodiment, FAU framework type zeolite with a SiO 2(FAU) / Al2O 3(FAU) molar ratio greater than or equal to 6.00, preferably 6.00 to 200, preferably 6.0 to 100, can be incorporated into the reaction mixture for carrying out step (i) as a source of silicon and aluminum elements.

[0057] In another embodiment, FAU framework type zeolite and at least one other source of trivalent element in the form of Y2O3 can be used in step i), and the composition of the reaction mixture is such that (SiO 2(FAU) ) / (Al2O 3(FAU) +Y2O3) is 6 to 200, preferably 6 to 100.

[0058] In a preferred variant of this embodiment, when Y is aluminum and in step (i) a FAU framework type zeolite and at least one other aluminum source in the form of an oxide Al2O3 are used, the composition of the reaction mixture is such that (SiO 2(FAU) ) / (Al2O 3(FAU) +Al2O3) is from 6 to 200, preferably from 6 to 100, which means that the amount of alumina supplied by the FAU zeolite in the reaction mixture composition and the amount of alumina supplied by the other aluminum source are taken into account.

[0059] According to the invention, R is a nitrogen-containing organic compound, N-ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium hydroxide, and said compound is incorporated into the reaction mixture to be used as an organic structuring agent in step (i).

[0060] According to the invention, at least one source of at least one alkali metal and / or alkaline earth metal M with a valence of n is used in the reaction mixture of step (i), where n is an integer greater than or equal to 1, and M is preferably selected from: lithium, potassium, sodium, magnesium and calcium and mixtures of at least two of these metals. Very preferably, M can be sodium.

[0061] Preferably, the source of at least one alkali metal and / or alkaline earth metal M can be sodium hydroxide.

[0062] According to the invention, at least one other source of the Y2O3 oxide can be used in the mixture of step (i), where Y is one or more trivalent elements selected from the following elements: aluminum, boron, gallium. Preferably, Y can be aluminum.

[0063] The aluminum source is preferably aluminum hydroxide or an aluminum salt (e.g., chloride, nitrate or sulfate), sodium aluminate, an alkoxyaluminum or alumina itself (preferably in a hydrated or hydratable form, such as colloidal alumina, pseudoboehmite, γ-alumina or α- or β-aluminum trihydrate. Mixtures of the above sources can also be used. Very preferably, the other source of the Y2O3 oxide is sodium aluminate.

[0064] Step (i) of the process according to the invention comprises: preparing an aqueous reaction mixture comprising a FAU framework type zeolite, optionally a source of the Y2O3 oxide, at least one nitrogen-containing organic compound R, in the presence of at least one source of at least one alkali metal and / or alkaline earth metal, to obtain a precursor gel of a FER framework type zeolite, where R is N-ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium hydroxide. The amounts of the reagents in the reaction mixture are adjusted as described above so as to provide the gel with a composition capable of crystallizing the FER framework type IZM-8 zeolite.

[0065] It may be advantageous to add seeds of the FER framework type zeolite to the reaction mixture during step i) of the process of the present invention or to the precursor gel during step ii), preferably at the end of the ripening step ii), in order to reduce the time required to form the FER framework type zeolite crystals and / or the overall crystallization time. The seeds also promote the formation of the FER framework type IZM-zeolite and are not conducive to impurities. The seeds comprise a crystalline solid, in particular FER framework type zeolite crystals. The seeds are generally added in a proportion of 0.01% to 10% of the total mass of the sources of the tetravalent and trivalent elements used in the reaction mixture, and the seeds are not included in the total mass of the sources of the tetravalent and trivalent elements. When determining the composition of the above-mentioned reaction mixture and / or gel, i.e., when determining the various molar ratios of the reaction mixture composition (in particular (SIO 2(FAU) ) / (Al2O 3(FAU) +Y2O3), H2O / (SiO 2(FAU) ), R / (SiO 2(FAU) ), M 2 / n O / (SiO 2(FAU) ), these seeds are not taken into account.

[0066] The mixing step i) is carried out until a homogeneous mixture is obtained, preferably for a time of 5 minutes to 15 minutes, preferably under stirring at a low shear rate or a high shear rate by any system known to those skilled in the art.

[0067] At the end of step i), a homogeneous precursor gel is obtained.

[0068] The ripening step ii) of the reaction mixture before hydrothermal crystallization during step iii) of the process of the present invention enables the crystal size of the FER framework type IZM-8 zeolite to be controlled. The ripening also promotes the formation of the FER framework type zeolite and is not conducive to impurities. The ripening of the reaction mixture during step ii) of the process of the present invention can be carried out with or without stirring, at ambient temperature (usually considered to be equal to 20 °C) or at a temperature of 15 °C to 100 °C for 10 minutes to 48 hours, preferably 6 to 24 hours.

[0069] According to step ii) of the process of the present invention, the precursor gel obtained at the end of step ii) is subjected to a hydrothermal treatment at a temperature of 120 °C to 220 °C for 12 hours to 7 days until the FER framework type IZM-8 zeolite is formed.

[0070] Advantageously, under autogenous reaction pressure, optionally adding a gas (for example, nitrogen), at a temperature preferably of 120 °C to 220 °C, preferably 140 °C to 195 °C, the precursor gel is placed under hydrothermal conditions until the FER framework type IZM-8 zeolite is completely crystallized.

[0071] The time required to obtain the crystals is from 12 hours to 7 days, preferably from 12 hours to 6 days, more preferably from 12 hours to 3 days.

[0072] The reaction is usually carried out with or without stirring, preferably with stirring. Stirring systems that can be used are any systems known to those skilled in the art, such as inclined blades with opposed blades, stirring turbine mixers or Archimedes'screws.

[0073] At the end of the reaction, after carrying out step iii) of the preparation method of the present invention, the solid phase formed by the FER framework type IZM-8 zeolite is preferably filtered out, washed and then dried. Drying can generally be carried out at a temperature of 20 °C to 120 °C, preferably 60 °C to 100 °C for a time of 5 to 24 hours.

[0074] The dried zeolite can then be advantageously calcined. The calcined FER framework type IZM-8 zeolite is generally analyzed by X-ray diffraction, and this technique also makes it possible to determine the purity of the zeolite obtained by the method of the present invention.

[0075] Very advantageously, the method of the present invention results in the formation of FER framework type IZM-8 zeolite, which does not contain any other crystalline phase or amorphous phase. After the drying step, the FER framework type IZM-8 zeolite 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 employed.

[0076] The loss on ignition of the FER framework type IZM-8 zeolite obtained after drying and before calcination is generally 5 to 15% by weight. According to the present invention, the loss on ignition (LOI) refers to the percentage of mass loss experienced by the solid compound during heat treatment in a muffle furnace type furnace at 1000 °C for 2 hours relative to the mass of the initial solid compound (in the case of the present invention, preferably relative to the mass of the dried IZM-8 zeolite). The loss on ignition generally corresponds to the loss of solvent (such as water) and also corresponds to the removal of organic compounds contained in the solid.

[0077] The FER framework type IZM-8 zeolite obtained by the method according to the present invention can be advantageously calcined. The calcination step can preferably be carried out at a temperature of 450 °C to 700 °C for a time of 2 to 20 hours.

[0078] The FER framework type IZM-8 zeolite obtained at the end of the calcination step does not contain any organic substances, especially does not contain the organic structuring agent R.

[0079] At the end of the calcination step, X-ray diffraction can confirm that the solid obtained by the method of the present invention is indeed the FER framework type IZM-8 zeolite. Thus, relative to the total mass of the crystalline solid material obtained, the purity of the FER framework type IZM-8 zeolite obtained is greater than or equal to 90% by weight, preferably greater than or equal to 95% by weight, very preferably greater than or greater than 97%, more preferably greater than or less than 98%, even more preferably greater than or equal to 99%, or even greater than or equal to 99.8% by weight.

[0080] The obtained solid has an X-ray diffraction pattern that includes at least the lines recorded in Table 1. Preferably, the X-ray diffraction pattern does not contain any other lines that are significantly more intense (i.e., the intensity is approximately three times greater than the background noise) than those recorded in Table 1.

[0081] This diffraction pattern is obtained by irradiating with copper Kα1 radiation using a conventional powder method with a diffractometer for radioactive crystal analysis. Based on the position of the diffraction peaks represented by the angle 2θ, the lattice plane spacing d of the sample is calculated using Bragg's law hkl characteristics. The measurement error Δ(d hkl ) of dhkl is calculated by Bragg's law and the absolute error Δ(2θ) assigned to the 2θ measurement value. An absolute error Δ(2θ) equal to ±0.02° is generally accepted. The relative intensity I assigned to d hkl for each value is measured according to the height of the corresponding diffraction peak rel . The X-ray diffraction pattern of the FER framework type crystalline solid according to the present invention includes at least the lines at the d hkl values given in Table 1, giving the average values of d hkl and relative intensity measured on the X-ray diffraction pattern of the calcined crystalline solid of the FER framework type. In the column of d hkl values, the average value of the interlattice spacing is shown in Å units. A measurement error Δ(d to ) must be assigned to each of these values. hkl )

[0082] Table 1

[0083]

[0084] where VS = very strong; S = strong; m = medium; mw = medium-weak; w = weak; vw = very weak. The relative intensity I relGiven relative to a relative intensity scale, where the maximum intensity line in the X-ray diffraction pattern is taken as 100: vw < 15; 15 ≤ w < 30; 30 ≤ mw < 50; 50 ≤ m < 65; 65 ≤ S < 85; VS ≥ 85.

[0085] X-ray fluorescence spectrometry (XFS) is a technique for chemical analysis using the physical property of materials (X-ray fluorescence). It can analyze most chemical elements starting from beryllium (Be), with concentration ranges from several ppm to 100%, and the results are accurate and reproducible. X-rays are used to excite the atoms in the sample, causing them to emit X-rays with energy characteristics of the respective elements present. Then, the intensities and energies of these X-rays are measured to determine the concentrations of the elements in the material.

[0086] The specific surface area is calculated using the Brunauer-Emmett-Teller method (BET method) (Brunauer et al., Journal of The American Chemical Society 1938, 60(2), 309 - 319), and the micropore volume is calculated using the t-plot method (Storck et al., Applied Catalysis A: General 1998 174(1 - 2), 137 - 146).

[0087] The micropore volume of the calcined IZM-8 zeolite according to the present invention is advantageously from 0.122 to 0.136 cm 3 / g, and the BET specific surface area is advantageously from 325 to 400 m 2 / g.

[0088] It is also advantageous to obtain the protonated form of the FER framework type IZM-8 zeolite obtained by the method according to the present invention. The protonated form can be obtained by ion exchange with an acid, in particular a strong inorganic acid (such as hydrochloric acid, sulfuric acid or nitric acid), or with a compound (such as ammonium chloride, sulfate or nitrate). The ion exchange can be carried out by placing the FER framework type IZM-8 zeolite in suspension with the ion exchange solution one or more times. The zeolite can be calcined before, after or between two ion exchange steps. The zeolite is preferably calcined before ion exchange to remove any organic substances contained in the pores of the zeolite, as this can promote ion exchange.

[0089] The FER framework type IZM-8 zeolite obtained by the method of the present invention can be used as an acidic solid after ion exchange for catalysis in the refining and petrochemical fields. It can also be used as an adsorbent or molecular sieve.

[0090] Examples

[0091] Example 1: Preparation of N-ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium dihydroxide (structuring agent R)

[0092] Enamine synthesis: N-(3,3,5-trimethylcyclohex-1-enyl)pyrrolidine + N-(3,3,5-trimethylcyclohex-1-en yl)pyrrolidine:

[0093] 42.1 g (0.3 M) of 3,3,5-trimethylcyclohexanone and 64 g (0.9 M) of pyrrolidine were charged into a 1000 ml round-bottom flask, and then 500 ml of cyclohexane was added to dissolve the reactants. The reaction medium was stirred at a speed of 450 rpm, and then 65 g (0.54 M) of magnesium sulfate was added. The reaction medium was refluxed for 120 hours. After returning to ambient temperature, the obtained suspension was filtered through a porous frit 3. The resulting solid was washed twice with 50 ml of cyclohexane on the frit. After removing cyclohexane with a rotary evaporator, 54 g (yield 93%) of the product was obtained. 1 H and 13 The C NMR spectra were consistent with the structure of the expected product (specifically, the vinylic protons of the enamine at 4.05 and 4.11 ppm, and the vinylic carbons at 99.62, 105.62, 141.36 and 142.11 ppm).

[0094] Synthesis of N-(3,3,5-trimethylcyclohexyl)pyrrolidine:

[0095] 25.1 g (0.13 M) of enamine was charged into a 100 ml round-bottom flask, and then 13 g (0.282 M) of formic acid was added with stirring at a speed of 300 rpm. The reaction medium was then heated at 80 °C for 3 hours. After returning to ambient temperature, 20 g of 10% H2SO4 was added with stirring at 800 rpm, and the reaction medium was stirred overnight at ambient temperature.

[0096] 50 g of 20% NaOH and 150 ml of ether were added to obtain a biphasic medium with a pH > 10 in the aqueous phase. The organic phase was decanted, and then the aqueous phase was extracted twice with 100 ml of ether. The organic phases were combined and then dried with magnesium sulfate. After filtering off the magnesium sulfate and removing the ether with a rotary evaporator, 22.9 g (yield: 90%) of the product was obtained. 1 H and 13 The C NMR spectra were consistent with the structure of the expected product (specifically, the disappearance of the vinylic protons and vinylic carbons, and the conversion of the protons β to nitrogen at 2.29, 2.48 and 2.61 ppm).

[0097] Synthesis of N-ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium iodide:

[0098] 19.5 g (0.1 M) of N-(3,3,5-trimethylcyclohexyl)pyrrolidine was charged into a 500 ml round-bottom flask, and then 250 ml of acetonitrile was added to dissolve N-(3,3,4-trimethylcyclohexyl)pyrrolidine. While stirring at 200 rpm (magnetic stir bar), the reaction medium was heated to 60 °C, and then 62.3 g (0.4 M) of iodoethane was added over 22 minutes. The reaction medium was maintained at 60 °C for 24 hours.

[0099] After evaporation of the acetonitrile, 34.9 g (crude yield 99.5%) of the crude product was obtained.

[0100] The solid was dissolved in 290 ml of acetone. After heating to reflux to obtain a solution, 140 ml of ether was added, and a white solid precipitate was observed. After returning to ambient temperature, the resulting suspension was filtered through a fritted glass 3. The solid obtained was washed on the frit with 100 ml of a 1 / 2 mixture of ether / acetone.

[0101] 29 g of wet solid was thus obtained. The solid was then dried overnight in a ventilated oven at 45 °C to constant weight. 23.7 g (yield 68%) of the product was obtained.

[0102] Due to the presence of two diastereoisomers, 1 H and 13 the 1H and 13C NMR spectra were complex but consistent with the structure of the expected product (protons β to nitrogen at 3.38 and 3.58 ppm). The product appeared to be of high purity, and no signals corresponding to the presence of impurities were observed.

[0103] Synthesis of N-ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium hydroxide:

[0104] 18.8 g of Ag2O (0.08 mol, 99%, Aldrich) was placed in 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 was stirred in the dark for 12 hours. The mixture was then filtered. The filtrate obtained contained an aqueous solution of N-ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium hydroxide. Quantitative measurement of this substance was carried out by proton NMR.

[0105] Example 2: Preparation of FER framework type IZM-8 zeolite

[0106] 5.26 g of deionized water was mixed with 0.43 g of sodium hydroxide (99.5 wt%, Aldrich). 2.36 g of FAU framework zeolite (CBV720, SiO2 / Al2O3 = 34.7, Molecular Sieves International, LOI = 8.54%) was added to the above mixture, and the obtained preparation was kept stirred for 15 minutes. 2.65 g of an aqueous solution of N-ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium hydroxide (21.68 wt%) prepared according to Example 1 was added to the synthesis mixture and stirred for 10 minutes. The synthesis mixture was kept stirred for 24 minutes. The molar composition of the mixture was as follows: 1SiO2:0.03Al2O3:0.074R:0.165Na2O:13.4H2O, i.e., the SiO2 / Al2O3 ratio was 33. Then, after homogenization, the precursor gel was transferred to an autoclave. The autoclave was closed and then stirred and heated at 150 °C at a rotational discharge system at a rotation speed of 35 rpm for 6 days. The obtained crystal product was filtered out, washed with deionized water, and then dried overnight at 100 °C. Then the solid was introduced into a muffle furnace, and a calcination step was carried out in the furnace: the calcination cycle included heating the temperature to 200 °C at a rate of 1.5 °C / minute, maintaining a stable stage at 200 °C for 2 hours, heating the temperature to 550 °C at a rate of 1 °C / minute, subsequently maintaining a stable stage at 550 °C for 8 hours, and then returning to room temperature.

[0107] The calcined solid product was analyzed by X-ray diffraction and was identified as consisting of FER framework IZM-8 zeolite with a purity equal to 91 wt%. Determined by X-ray fluorescence, the SiO2 / Al2O3 molar ratio of the product was 19. The BET specific surface area and micropore volume were 345 m 2 / g and 0.122 cm 3 / g, respectively.

[0108] Example 3: Preparation of FER framework IZM-8 zeolite

[0109] 4.29 g of deionized water was mixed with 0.33 g of sodium hydroxide (99.5 wt%, Aldrich). 2.17 g of FAU framework zeolite (CBV780, SiO2 / Al2O3 = 96.2, Zeolyst, LOI = 14%) was added to the above mixture, and the resulting preparation was kept stirred for 15 minutes. 3.23 g of an aqueous solution of N-ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium hydroxide (26.2 wt%) prepared according to Example 1 was added to the synthesis mixture and stirred for 10 minutes. Subsequently, 0.11 g of sodium aluminate (NaAlO2, 53 mass% of Al2O3, Carlo Erba) was added to the synthesis mixture and kept stirred for 24 hours. The molar composition of the mixture was as follows: 1SiO2:0.031Al2O3:0.12R:0.165Na2O:13.6H2O, i.e., the SiO2 / Al2O3 ratio was 33. Then, after homogenization, the precursor gel was transferred to an autoclave. The autoclave was closed and then stirred and heated at 150 °C at 35 rpm with a rotary ejection system for 6 days. The obtained crystal product was filtered out, washed with deionized water, and then dried overnight at 100 °C. Then the solid was introduced into a muffle furnace, and a calcination step was carried out in the furnace: the calcination cycle included raising the temperature to 200 °C at 1.5 °C / min, holding at a stable stage of 200 °C for 2 hours, raising the temperature to 550 °C at 1 °C / min, subsequently holding at a stable stage of 550 °C for 8 hours, and then returning to room temperature.

[0110] The calcined solid product was analyzed by X-ray diffraction and was identified as consisting of FER framework IZM-8 zeolite with a purity equal to 91 wt%. The diffraction pattern generated by this solid is provided in Figure 2 The SiO2 / Al2O3 molar ratio of the product was determined by X-ray fluorescence to be 19.5. The BET specific surface area and micropore volume were 350 m 2 / g and 0.120 cm 3 / g, respectively.

[0111] Example 4: Preparation of FER framework IZM-8 zeolite by adding seeds

[0112] 4.26 g of deionized water was mixed with 0.33 g of sodium hydroxide (99.5 wt%, Aldrich). 2.14 g of FAU framework zeolite (CBV780, SiO2 / Al2O3 = 96.2, Zeolyst, LOI = 14%) was added to the above mixture, and the obtained preparation was kept stirred for 15 minutes. 3.18 g of an aqueous solution of N-ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium hydroxide (26.2 wt%) prepared according to Example 1 was added to the synthesis mixture and stirred for 10 minutes. Subsequently, 0.10 g of sodium aluminate (NaAlO2, 53 mass% of Al2O3, Carlo Erba) was added to the synthesis mixture and kept stirred for 24 hours. The molar composition of the mixture was as follows: 1SiO2:0.03Al2O3:0.12R:0.168Na2O:13.6H2O, i.e., the SiO2 / Al2O3 ratio was 33. Seeds of FER framework zeolite (0.17 g of FER zeolite with a SiO2 / Al2O3 molar ratio of 9.9) were added to the mixture. Then, after homogenization, the precursor gel was transferred to an autoclave. The autoclave was closed and then stirred and heated at 150 °C at 35 rpm with a rotary ejection system for 3 days. The obtained crystal product was filtered out, washed with deionized water, and then dried overnight at 100 °C. Then the solid was introduced into a muffle furnace, and a calcination step was carried out in the furnace: the calcination cycle included raising the temperature to 200 °C at 1.5 °C / min, holding at a stable stage of 200 °C for 2 hours, raising the temperature to 550 °C at 1 °C / min, subsequently holding at a stable stage of 550 °C for 8 hours, and then returning to room temperature.

[0113] The calcined solid product was analyzed by X-ray diffraction and was identified as consisting of FER framework IZM-8 zeolite with a purity greater than 99 wt% (ICDD file, PDF 01-073-9977). The diffraction pattern generated by the solid is provided in Figure 3 ... By X-ray fluorescence method, the SiO2 / Al2O3 molar ratio of the product was determined to be 15.8. The BET specific surface area and micropore volume were 364 m 2 / g and 0.128 cm 3 / g, respectively.

[0114] Example 5: Preparation of FER framework IZM-8 zeolite by adding seeds

[0115] 4.26 g of deionized water was mixed with 0.33 g of sodium hydroxide (99.5 wt%, Aldrich). 2.14 g of FAU framework zeolite (CBV780, SiO2 / Al2O3 = 96.2, Zeolyst, LOI = 14%) was added to the above mixture, and the resulting preparation was kept stirred for 15 minutes. 3.18 g of an aqueous solution of N-ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium hydroxide (26.2 wt%) prepared according to Example 1 was added to the synthesis mixture and stirred for 10 minutes. Subsequently, 0.10 g of sodium aluminate (NaAlO2, 53 mass% of Al2O3, Carlo Erba) was added to the synthesis mixture and kept stirred for 24 hours. The molar composition of the mixture was as follows: 1SiO2:0.03Al2O3:0.12R:0.168Na2O:13.6H2O, i.e., the SiO2 / Al2O3 ratio was 33. Seeds of FER framework zeolite (0.087 g of FER zeolite with a SiO2 / Al2O3 molar ratio of 9.9) were added to the mixture. Then, after homogenization, the precursor gel was transferred to an autoclave. The autoclave was closed and then stirred and heated at 150 °C at 35 rpm with a rotary ejection system for 3 days. The obtained crystal product was filtered out, washed with deionized water, and then dried overnight at 100 °C. Then the solid was introduced into a muffle furnace where a calcination step was carried out: the calcination cycle included increasing the temperature to 200 °C at 1.5 °C / min, holding at a stable stage of 200 °C for 2 hours, increasing the temperature to 550 °C at 1 °C / min, subsequently holding at a stable stage of 550 °C for 8 hours, and then returning to room temperature.

[0116] The calcined solid product was analyzed by X-ray diffraction and was identified as consisting of FER framework IZM-8 zeolite with a purity greater than 99 wt% (ICDD file, PDF 01-073-9977). The BET specific surface area and micropore volume were 360 m 2 / g and 0.125 cm 3 / g, respectively.

[0117] Example 6: Synthesis not according to the present invention

[0118] 6.6 g of deionized water was mixed with 0.297 g of sodium hydroxide (99.5 wt%, Aldrich). 2.36 g of FAU framework zeolite (CBV720, SiO2 / Al2O3 = 34.7, Molecular Sieve International Corporation, LOI = 8.54%) was added to the above mixture, and the obtained preparation was kept stirred for 15 minutes. 1.52 g of an aqueous solution of N-ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium hydroxide (26.20 wt%) prepared according to Example 1 was added to the synthesis mixture and stirred for 10 minutes. The mixture was kept stirred for 24 hours. The molar composition of the mixture was as follows: 1SiO2:0.03Al2O3:0.074R:0.165Na2O:20H2O, i.e., the SiO2 / Al2O3 ratio was 33. Then, after homogenization, the precursor gel was transferred to an autoclave. The autoclave was closed and then stirred and heated at 150 °C at 35 rpm with a rotary ejection system for 6 days. The obtained crystal product was filtered out, washed with deionized water, and then dried overnight at 100 °C. Then the solid was introduced into a muffle furnace, and a calcination step was carried out in the furnace: the calcination cycle included increasing the temperature to 200 °C at 1.5 °C / min, holding at a stable stage of 200 °C for 2 hours, increasing the temperature to 550 °C at 1 °C / min, subsequently holding at a stable stage of 550 °C for 8 hours, and then returning to room temperature.

[0119] The calcined solid product was analyzed by X-ray diffraction and was identified as consisting of MOR framework zeolite with a purity greater than 99 wt% (ICDD file, PDF 04-023-4678).

Claims

1. A method for preparing high-purity FER framework type IZM-8 zeolite, said method comprising at least the following steps: i) Mixing in an aqueous medium a FAU framework type zeolite as a silicon source in the form of SiO2 and an aluminum source in the form of Al2O3, a nitrogen-containing organic compound R, at least one alkali metal and / or alkaline earth metal M of valence n, and optionally a source of a trivalent element in the form of Y2O3 until a homogeneous precursor gel is obtained, wherein R is N-ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium hydroxide, n is an integer greater than or equal to 1, and the mixture has the following molar composition: (SiO 2(FAU) ) / (Al2O 3(FAU) +Y2O3) is from 6 to 200, preferably from 6 to 100, H2O / (SiO 2(FAU) ) is from 1 to 16, preferably from 5 to 14, R / (SiO 2(FAU) ) is from 0.01 to 0.5, preferably from 0.04 to 0.3, M 2 / n O / (SiO 2(FAU) ) is from 0.005 to 0.45, preferably from 0.05 to 0.2, Wherein, Y is one or more trivalent elements selected from the following elements: aluminum, boron, gallium, SiO 2(FAU) is the amount of SiO2 provided by the FAU zeolite, and Al2O 3(FAU) is the amount of Al2O3 provided by the FAU zeolite, and M is one or more alkali metals and / or alkaline earth metals selected from lithium, sodium, potassium, calcium, magnesium, and mixtures of at least two of these metals; ii) Aging the homogeneous precursor gel obtained at the end of step i) for 10 minutes to 48 hours at a temperature of 15 °C to 100 °C, with or without stirring; iii) Hydrothermally treating the precursor gel obtained at the end of step ii) for 12 hours to 7 days (including the end values) at a temperature of 120 °C to 220 °C until FER framework type IZM-8 zeolite is formed.

2. The method according to claim 1, wherein M is sodium, and preferably the source of at least one alkali metal M is sodium hydroxide.

3. The method according to any one of the preceding claims, wherein, Y is aluminum.

4. The method according to any one of the preceding claims, wherein, Seeding crystals of FER framework type zeolite are added to the reaction mixture of step i) or the homogeneous precursor gel of step ii) in an amount of 0.01-10% of the total mass of the anhydrous forms of the Si and Al element sources used in the reaction mixture, and the seeding crystals are not included in the total mass of the Si and Al element sources.

5. The method according to any one of the preceding claims, wherein, The aging in step ii) is carried out with stirring for 6 to 24 hours (including the end values) at ambient temperature.

6. The method according to any one of the preceding claims, wherein, The hydrothermal treatment in step iii) is carried out under autogenous reaction pressure.

7. The method according to any one of the preceding claims, wherein, The hydrothermal treatment in step iii) is carried out at a temperature of 140 °C to 195 °C.

8. The method according to any one of the preceding claims, wherein, After carrying out step iii), the solid phase formed by FER framework type IZM-8 zeolite obtained at the end of step iii) is filtered out, washed, and dried at a temperature of 20 °C to 150 °C, preferably 60 °C to 100 °C, for 5 to 24 hours to obtain a dried zeolite.

9. The method according to claim 8, wherein, The dried zeolite is then calcined at a temperature of 450 °C to 700 °C for 2 hours to 20 hours, and the calcination may be carried out by gradually increasing the temperature.

10. A FER framework type IZM-8 zeolite obtained by the preparation method according to any one of claims 1 to 9, having a purity greater than or equal to 90% by weight, preferably greater than 95% by weight, and an SiO2 / Al2O3 ratio of 15 to 30 (including the end values), preferably 10 to 25 (including the end values).

11. A FER framework type IZM-8 zeolite obtained by the preparation method according to claim 9, having a purity of greater than or equal to 90% by weight, preferably greater than 95% by weight, an SiO2 / Al2O3 ratio of 15 to 30 (including the end values), preferably 10 to 25 (including the end values), wherein the d hkl and the average values of the relative intensities are as follows: VS = very strong; S = strong; m = medium; mw = medium-weak; w = weak; vw = very weak, and the relative intensity I rel is given with respect to a relative intensity scale, wherein the value of the strongest line in the X-ray diffraction pattern is set at 100: vw < 15; 15 ≤ w ≤ 30; 30 ≤ mw < 50; 50 ≤ m < 65; 65 ≤ S < 85; VS ≥ 85: Table 1 12. The FER framework type IZM-8 zeolite as claimed in claim 11, having a micropore volume of 0.122 to 0.136 cm 3 / g and a BET specific surface area of 325 to 400 m 2 / g.

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