Process for the synthesis of a very high purity IZM-10 zeolite of AEI structural type in the presence of a nitrogenous organic structuring agent

Abstract

The invention relates to a process for preparing an IZM-10 zeolite of AEI structural type comprising at least the mixture in aqueous medium of a zeolite of FAU structural type having a SiO2 (FAU) / Al2O3 (FAU) molar ratio of between 10 and 60, limits included, and a mass percentage of sodium in cationic form of less than 0.005%, of a nitrogenous organic compound R, R being (6R,10S)-6,10-dimethyl-5-azoniaspiro[4,5]decane in its hydroxide form and optionally sodium hydroxide, then the hydrothermal treatment of the precursor gel obtained at the end of step i). The invention also relates to the zeolite of structural type AEI with a SiO2 / Al2O3 molar ratio of between 10 and 60, limits included, with a purity greater than or equal to 98% by weight, preferably greater than or equal to 99% by weight, in partially or totally protonated form, obtained by the process. Figure to be published: Figure 3

Description

Title of the invention: Process for the synthesis of a very high purity IZM-10 zeolite of AEI structural type in the presence of a nitrogenous organic structuring agent Technical field

[0001] The present invention relates to a new process for preparing an IZM-10 zeolite of AEI structural type. This new process makes it possible to carry out the synthesis of an IZM-10 zeolite of AEI structural type by conversion / transformation under hydrothermal conditions of a zeolite of FAU structural type. In particular, said new process makes it possible to carry out the synthesis of an IZM-10 zeolite of AEI 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, (6R,10S)-6,10-dimethyl-5-azoniaspiro[4,5]decane in its hydroxide form. Said IZM-10 zeolite of AEI structural type obtained according to the process of the invention advantageously finds its application as a catalyst, adsorbent or separation agent. Prior art

[0002] Crystallized microporous materials, such as zeolites or silicoaluminophosphates, are solids widely used in the petroleum industry as catalyst, catalyst support, adsorbent or separation agent. Although many microporous crystalline structures have been discovered, the refining and petrochemical industry is always looking for new zeolitic structures that have particular properties for applications such as gas purification or separation, conversion of carbon species or others.

[0003] Zeolites of structural type AEI include in particular zeolite SSZ-39 (Wagner, P et al., J. Am. Chem. Soc., 122, 263-273 (2000)), and zeotypes ALPO-18 (Simmen, A. et al., Zeolites, 11, 654-661 (1991)) and SAPO-18 (Chen, JS et al., Catalysis Letters, 28, 241-248 (1994)). The structural type "AEI" is defined by the "Structure Commission" of the International Zeolite Association (IZA).

[0004] Zeolites of structural type AEI have a three-dimensional system of pores delimited by eight TO4 tetrahedra and obtained by the three-dimensional connection of double cycles of atoms T (D6R) or T can be silicon, aluminum or phosphorus. Many methods for synthesizing zeolites of structural type AEI are known. They require the simultaneous use of an organic structuring agent and an inorganic base (sodium or potassium hydroxide). To obtain the protonated form of the zeolite it is necessary to carry out an ion exchange step with NH4 N03, NH4C1, ammonium acetate or any other aqueous source of ammonium cations.

[0005] Patent application CN112758954 presents the synthesis of a core-layer SSZ-39 zeolite where the core contains copper. The synthesis is carried out in the presence of sodium or potassium hydroxide in the presence of an organic structuring agent chosen from the ions of: N,N-diethyl-2,6-dimethylpiperidine, 1,1,3,5-tetramethylpiperidine, 2,6-dimethyl-5-azoniumspiro-[4,5]-decane, N,N-diethyl-2-ethylpiperidine, N-ethyl-N-propane-2,6-dimethylpiperidine, N-methyl-N-ethyl-2,6-dimethylpiperidine, N-methyl-N-ethyl-2-ethylpiperidine, 2,5-dimethyl-N,N-diethylpyrrole, 2,6-dimethyl-N,N-dimethylpiperidine, 3,5-dimethyl-N,N-dimethylpiperidine, 2-Ethyl-N,N-dimethylpiperidine, 2,2,6,6-Tetramethyl-N-methyl-N-ethylpiperidine, N-cyclooctyl-pyridine, 2,2,6,6-tetramethyl-N,N-dimethylpiperidine and N,N-dimethyl-N,N-bicyclononane, preferably the organic structuring agent is chosen from: N,N-diethyl-2,6-dimethylpiperidine and / or 3,5-dimethyl-N,N-dimethylpiperidine.The molar ratio Na2O(NaOH) / SiO2 in the synthesis mixture is between 0.05 and 0.25. To obtain the protonated form of the zeolite, it is necessary to carry out an ion exchange step with NH4NO3.

[0006] Patent application US2022106192 presents the synthesis of a zeolite of structural type AEI in the presence of an organic structuring agent of N,N-dialkyl-dialkylpiperidinium cation type of N,N-(Cl-C3)-dialkyl-(Cl-C3)-dialkylpiperldinium cation, preferably an N,N-(Cl-C2)-dialkyl-(Cl-C3)-dialkylpiperidinium cation, preferably the N,N-diethyl-2.6-dimethylpiperidinium cation, more preferably the N,N-diethyl-cis-2.6-dimethylpiperidinium cation. The synthesis of the zeolite is carried out in the presence of sodium hydroxide in addition to any other source of Na cations. The molar ratio Na2 O(NaoH) / SiO2 in the synthesis mixture is between 0.25 and 1. Preferably, the synthesis gel does not contain a zeolite of structural type FAU. To obtain the protonated form of the zeolite, it is necessary to carry out an ion exchange step with NH4NO3.

[0007] The article “Hydrothermal Conversion of Titanated FAU to AEI Zeolite and Its Enhanced Catalytic Performance for NOx Reduction” (Adv. Porous Mater. 2016, VOL 4, No. 1, 62) presents the synthesis of an AEI zeolite using [Al, Ti] FAU zeolite as a source of silicon and aluminum in the presence of sodium hydroxide and the organic structuring agent: 1,1-diethyl-2,6-dimethylpiperidinium hydroxide (DEDMPOH). The molar ratio Na2O(NaOH) / SiO2 in the synthesis mixture is 0.1. To obtain the protonated form of the zeolite it is necessary to carry out an ion exchange step with NH4NO3.

[0008] Patent application CN105314646A presents the synthesis of a zeolite of structural type AEI in the presence of an organic structuring agent chosen from the cations: l-methyl-2,6-dimethyl-piperidine, l-ethyl-2,6-dimethyl-piperidine, l-methyl-3,5-dimethyl-piperidine, l-ethyl-3,5-dimethyl-piperidine, 1.1 -dimethyl-2,6-dimethyl-piperidine, 1,1 -diethyl-2,6-dimethyl-piperidine, l,l-dimethyl-3,5-dimethyl-piperidine, l-ethyl-3,5-dimethyl-piperidine, l,l-bis-ethyl-2,6-dimethyl-piperidine, l,l-diethyl-3,5-dimethyl-piperidine. The synthesis of AEI structural type zeolite is carried out in the presence of sodium or potassium hydroxide. The molar ratio Na2O(NaOH) / SiO2 in the synthesis mixture is between 0.1 and 0.5. To obtain the protonated form of the zeolite, it is necessary to carry out an ion exchange step with NH4NO3.

[0009] Patent application CN107285333A presents the synthesis of a zeolite of structural type AEI using microwaves and in the presence of an organic structuring agent chosen from the cations: 1,1,2,2,6,6-hexamethylpiperidinium, 1,1,2,2,6,6-hexamethyl-4-oxo-piperidinium, 1,1,3,5-tetramethyl-4-oxo-piperidine, 1 -hydroxy-1,1,2,2,6,6-hexamethylpiperidinium, 1,1-dimethyl-4,4-propoxypiperidinium, 3,5-dimethoxy-1,1-dimethyl piperidinium, 3,5-dihydroxy-1,1-dimethyl piperidinium, 4-ethyl-1,1-dimethyl-3,5-dioxo-pyridinium, 1 -ethyl-1 -methyl-2,2,6-methyl-piperidine, l-epoxy-propyl-l-methyl-2,2,6,6-hexamethylpiperidinium. The synthesis of the AEI structural type zeolite is carried out in the presence of sodium or potassium hydroxide. The molar ratio Na2O(NaOH) / SiO2 in the synthesis mixture is between 0.1 and 0.5.

[0010] Patent application CN107308980A presents the use of a zeolite of structural type AEI containing copper in NH3-SCR. The synthesis of zeolite of structural type AEI is carried out in the presence of sodium hydroxide and an organic structuring agent chosen from the cations: 1,1,2,2,6,6-hexamethylpiperidinium, 1,1,2,2,6,6-hexamethyl-4-oxo-piperidinium, 1,1,3,5-tetramethyl-4-oxo-piperidine, 1 -hydroxy-1,1,2,2,6,6-hexamethylpiperidinium, l,l-dimethyl-4,4-propoxypiperidinium, 3,5-dimethoxy-l, 1-dimethyl piperidinium, 3,5-dihydroxy-1,1-dimethyl piperidinium, 4-ethyl-1,l-dimethyl-3,5-dioxo-pyridinium, 1 -ethyl-1 -methyl-2,2,6-methyl-piperidine, l-epoxy-propyl-l-methyl-2,2,6,6-hexamethylpiperidinium. The molar ratio of Na2O (NaOH) / SiO2 in the synthesis mixture is between 0.1 and 0.5.

[0011] Patent US5958370 presents the synthesis of a SSZ-39 zeolite of structural type AEI in the presence of sodium hydroxide and an organic structuring agent chosen from the cations: N,N-Diethyl-2,6-dimethylpiperidinium, N,N-Dimethyl-9-azoniabicyclo[3. 3. l]nonane, N,N-Dimethyl-2,6-dimethylpiperidinium, N- Ethyl-N-methyl-2,6-dimethylpiperidinium, N,N-Diethyl-2-ethylpiperidinium, N,N-Dimethyl-2-(2-hydroxyethyl)piperidinium, N,N-Dimethyl-2-ethylpiperidinium, N,N-Dimethyl-3,5-dimethylpiperidinium, N-Ethyl-N-methyl-2-ethylpiperidinium, 2,6-Dimethyl-l-Azonium[5.4]decane, N-Ethyl-N-propyl-2,6-dimethylpiperidinium, 2,2,4,6,6-Pentamethyl-2-azoniabicyclo[3.2.1]octane, N,N-Diethyl-2,5-dimethyl-2,5-dihydropyrrolium. The molar ratio Na2O(NaOH) / SiO2 in the synthesis mixture is between 0.3 and 1. The synthesis times are greater than 6 days. According to this patent, the structuring agents: N,N-Dimethyl-2-ethylpiperidinium, N-Ethyl-N-methyl-2-ethylpiperidinium, 2,6-Dimethyl-1-Azonium[5.4]decane and N-Ethyl-N-propyl-2,6-dimethylpiperidinium do not allow to obtain a pure SSZ-39 zeolite of AEI structural type, analcime impurities are present. To obtain the protonated form of the zeolite, it is necessary to carry out an ion exchange step with NH4NO3.

[0012] Patent application US2017128921 presents the synthesis of a zeolite of structural type AEI in the presence of sodium hydroxide and an organic structuring agent chosen from the cations: N,N-dimethyl-3,5-dimethylpiperidinium, N,N-dimethyl-2-(2-hydroxyethyl)piperidinium, N,N-dimethyl-2-ethylpiperidinium and 2,2,4,6,6-pentamethyl-2-azoniabycyclo[3.2.1]octane. The molar ratio Na2O(NaOH) / SiO2 in the synthesis mixture is between 0.2 and 1. To obtain the protonated form of the zeolite it is necessary to carry out an ion exchange step with ammonium acetate.

[0013] The article “Transformation synthesis of aluminosilicate SSZ-39 zeolite from ZSM-5 and beta zeolite” (J. Mater. Chem. A, 2019, 7, 4420) presents the synthesis of an SSZ-39 zeolite of structural type AEI by interzeolitic transformation in the presence of the organic structuring agent N,N-diethyl-cis-2,6-dimethylpiperidine hydroxide and sodium hydroxide. The molar ratio Na2O(NaOH) / SiO2 in the synthesis mixture is 0.17. To obtain the protonated form of the zeolite it is necessary to carry out an ion exchange step with NH4NO3.

[0014] The article “Synthesis of high-silica AEI zeolites with enhanced thermal stability by hydrothermal conversion of FAU zeolites, and their activity in the selective catalytic reduction of NOx with NH3 (J. Mater. Chem. A, 2015, 3, 857) presents the synthesis of a zeolite of structural type AEI by interzeolitic transformation in the presence of the organic structuring agent tetraethylphosphonium in fluoride medium. This synthesis makes it possible to obtain a zeolite of structural type AEI more stable at high temperature than that obtained with the organic structuring agent N,N-diethyl-2,6-dimethylpiperidinium in basic medium. The molar ratio Na2O(NaOH) / SiO2 in the synthesis mixture is 0.05. To obtain the protonated form of the zeolite, it is necessary to carry out an ion exchange step with NH4C1.

[0015] Patent application US2018093257 presents the synthesis of a JMZ-8 zeolite of structural type AEI in the presence of sodium hydroxide and an organic structuring agent R chosen from N,N-diethyl-cis-2,6-dimethylpiperidinium or NN-Dimethyl-3.5-dimethylpiperidinium. The molar ratio Na2O(NaOH) / Al2O3 in the synthesis mixture is between 0.5 and 2. The purity of the AEI zeolite obtained is greater than 90%. To obtain the protonated form of the zeolite it is necessary to carry out an ion exchange step with NH4NO3.

[0016] Patent US2018093256 presents the synthesis of a JMZ-9 zeolite of structural type AEI in the presence of an organic structuring agent R chosen from N,N-diethyl-cis-2,6-dimethylpiperidinium or NN-Dimethyl-3.5-dimethylpiperidinium or the mixture of the two. The molar ratios claimed are: (SiO2)) / (Al2O3) between 20 and 50, H2O / SiO2 between 10 and 40, R / SiO2 between 0.25 and 1, HO / SiO2 between 0.25 and 1,

[0017] Patent application US2020-0360906A1 presents the synthesis of a JMZ-8 zeolite of structural type AEI in the presence of sodium hydroxide and an organic structuring agent R chosen from N,N-diethyl-cis-2,6-dimethylpiperidinium or NN-Dimethyl-3.5-dimethylpiperidinium. The molar ratio Na2O(NaOH) / Al2O3 in the synthesis mixture is between 0.5 and 2. The purity of the AEI zeolite obtained is greater than 90%. To obtain the protonated form of the zeolite it is necessary to carry out an ion exchange step with NH4NO3.

[0018] Patent application WO2016 / 166245 presents the synthesis of a zeolite of structural type AEI in the presence of sodium hydroxide and an organic structuring agent chosen from: NN-Dimethyl-3.5-dimethylpiperidinium, N,N-diethyl-2,6-dimethylpiperidinium (DEDMP), N,N-dimethyl-2,6-dimethylpiperidinium, N-ethyl-N-methyl-2,6-dimethylpiperidinium alone or in a mixture. The molar ratio Na2O(NaOH) / Al2O3 in the synthesis mixture is between 0.001 and 2. To obtain the protonated form of the zeolite, it is necessary to carry out an ion exchange step with NH4NO3. Summary of the invention

[0019] Surprisingly, the applicant has discovered that it is possible to obtain a zeolite of structural type AEI in the presence of the organic structuring agent (6R,10S)-6,10-dimethyl-5-azoniaspiro[4,5]decane in its hydroxide form, without adding or by adding a very small amount of sodium hydroxide (NaOH) to the synthesis. In addition, the partially or totally protonated form of said zeolite is obtained by direct calcination after synthesis without the need to first go through an exchange step with a soluble source of ammonium cations. For the purposes of the present invention, the term "partially protonated" means an AEI zeolite comprising an Al2O3 / Na2O molar ratio of between 100 and 400, and “fully protonated” an AEI zeolite comprising an Al2O3 / Na2O molar ratio of greater than 400.

[0020] The invention relates to a process for preparing an IZM-10 zeolite of AEI structural type comprising at least the following steps:

[0021] i) the mixture in aqueous medium of a zeolite of structural type FAU having a molar ratio SiO2 (fau / A12O3 (FAu) of between 10 and 60, limits included and a mass percentage of sodium in cationic form of less than 0.005%, of an organic nitrogen compound R, R being (6R,10S)-6,10-dimethyl-5-azoniaspiro[4,5]decane in its hydroxide form and optionally sodium hydroxide, the reaction mixture having the following molar composition:

[0022] (SiO2 (FAU)) / (A12O3 (FAU)) between 10 and 60, preferably between 30 and 50

[0023] H2O / (SiO2 (FAU)) between 20 and 60, preferably between 30 and 50

[0024] R / (SiO2 (FAU)) between 0.05 and 0.70, preferably between 0.15 and 0.60

[0025] Na2O (Naou) / (SiO2 (FAU)) between 0 and 0.20, preferably between 0 and 0.15

[0026] Na2O (FAu / (SiO2 (FAU)) between 3.5*105 and 7*10\ preferably between 4*105 and 6*105

[0027] in which Na2O (FAU) denotes the quantity of Na2O provided by the FAU zeolite, Na2O (Naou) denotes the quantity of Na2O provided by the soda, SiO2(FAU) denotes the quantity of SiO2 provided by the FAU zeolite, and A12O3 (FAU) denotes the quantity of Al2 O3 provided by the FAU zeolite, until a homogeneous precursor gel is obtained;

[0028] ii) the hydrothermal treatment of said precursor gel obtained at the end of step i) at a temperature between 120°C and 220°C, for a duration between 12 hours and 7 days.

[0029] Advantageously, the SiO2 / Al2O3 molar ratio of the AEI zeolite obtained can be between 10 and 60, preferably between 12 and 50, limits included, and the Al2O3 / Na2O molar ratio of the AEI zeolite obtained is advantageously greater than 100, preferably greater than 400.

[0030] Advantageously, the FAU structural type zeolite can have a SiO2 / Al2O3 molar ratio of between 20 and 50, limits included, and a mass percentage of sodium in cationic form of less than 0.0048%.

[0031] Advantageously, no sodium hydroxide is added to the synthesis gel (ratio Na2 O (NaOH) / (SiO2 (FAU)) = 0) and the protonated form of the IZM-10 zeolite of structural type AEI is directly obtained.

[0032] Crystalline seeds of a zeolite of structural type AEI can be added to the reaction mixture of step i), preferably in an amount of between 0.01 and 10% by weight relative to the total mass of the sources of the tetravalent and trivalent elements. in anhydrous form present in said mixture, said crystalline seeds not being taken into account in the total mass of the sources of SiO2 and A12O3.

[0033] Step i) may comprise a step of maturing the reaction mixture at a temperature of between 20 and 100°C, with or without stirring, for a period of between 30 minutes and 48 hours.

[0034] The hydrothermal treatment of step ii) can be carried out under autogenous pressure at a temperature between 120°C and 220°C, preferably between 150°C and 200°C, even more preferably between 160°C and 195°C, for a duration between 12 hours and 7 days, preferably between 12 hours and 6 days.

[0035] The solid phase obtained at the end of step ii) can be filtered, washed, and dried at a temperature between 20 and 150°C, preferably between 60 and 100°C, for a period of between 5 and 24 hours to obtain a dried zeolite.

[0036] The dried zeolite can then be calcined at a temperature between 450 and 700°C for a period of between 2 and 20 hours, the calcination possibly being preceded by a gradual increase in temperature.

[0037] The invention also relates to a zeolite of structural type AEI with a SiO2 / Al2O3 molar ratio of between 10 and 60, limits included, with a purity greater than or equal to 98% by weight, preferably greater than or equal to 99% by weight, very preferably greater than or equal to 99.8% by weight, in partially or totally protonated form, obtained by the method described above and comprising the following significant X-ray diffraction lines:

[0038] [Tableauxl] 2 theta O 2 theta C) M ;(A) ImJ 9.530 9.241 FF 25.371 3.508 1 10.690 8.268 r 26.066 3.416 ff 13.000 6.805 ff 26.47 3.365 f 13.554 6.528 a. 27.317 3 262 ff 14.019 6.312 s. 28,002 3,184 f 14,811 5,976 a 29,481 3,027 ff 16,179 5,474 f 29,841 2,992 ff 17,019 5,206 mf 30,19 2,958 ff 17,313 5,118 mf 30,605 2,919 Et 19,179 4,624 SL 31,033 2,879 ET 19,762 4,489 ff 31,335 2,852 F 20,158 4,402 fl 31,869 2,806 O 20,78 4,271 f 32,409 2,760 F 21,472 4,135 f 32,924 2,718 a 22,103 4,018 fl 33,206 2,696 Et 22,609 3,930 ff 33,986 2,636 Et 23,288 3,817 ff 34,514 2,597 Et 24,078 3,693 mf 34,994 2,562 H

[0039] 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 <f <30 ; 30 < mf <50 ; 50 <m < 65 ; 65 <F < 85 ; FF >85. LIST OF FIGURES [Fig 1]

[0040] [Fig. 1] represents the chemical formula of the organic nitrogen compound (6R,10S)-6,10-dimethyl-5-azoniaspiro[4,5]decane in its hydroxide form used in the synthesis process according to the invention. [Fig 2]

[0041] [Fig.2] represents the X-ray diffraction diagram of the IZM-10 zeolite of structural type AEI obtained according to example 2. [Fig 3]

[0042] [Fig.3] represents a Scanning Electron Microscope (SEM) image of the IZM-10 zeolite of structural type AEI obtained according to example 2. [Fig 4]

[0043] [Fig.4] represents the X-ray diffraction diagram of the mixture of zeolites of structural types AEI and MOR obtained according to comparative example 5.

[0044] Other characteristics and advantages of the synthesis method according to the invention will appear on reading the following description of non-limiting examples of embodiments, with reference to the appended figures described below. Description of the embodiments

[0045] The subject of the present invention is a new process for preparing an IZM-10 zeolite of AEI structural type, by conversion / transformation under hydrothermal conditions of a zeolite of FAU structural type having a mass percentage of sodium in cationic form of less than 0.005% and in the presence of a specific nitrogenous or structuring organic compound, (6R,10S)-6,10-dimethyl-5-azoniaspiro[4,5]decane in its hydroxide form.

[0046] The present invention more specifically relates to a new process for preparing an IZM-10 zeolite of AEI structural type comprising at least the following steps:

[0047] i) the mixture in aqueous medium of a zeolite of structural type FAU having a molar ratio SiO2(PAU) / Al2O3(pAu) of between 10 and 60, limits included and a mass percentage of sodium in cationic form of less than 0.005%, of an organic nitrogen compound R, R being (6R,10S)-6,10-dimethyl-5-azoniaspiro[4,5]decane in its hydroxide form and optionally sodium hydroxide, the reaction mixture having the following molar composition:

[0048] (SiO2 (fau)) / (A12O3 (fau)) between 10 and 60, preferably between 30 and 50

[0049] H2O / (SiO2 (fau)) between 20 and 60, preferably between 30 and 50

[0050] R / (SiO2 (fau)) between 0.05 and 0.70, preferably between 0.15 and 0.60

[0051] Na2O (NaOH) / (SiO2 (FAu)) between 0 and 0.20, preferably between 0 and 0.15

[0052] Na2O (FAu / (SiO2 (FAu)) between 3.5*105 and 7*105, preferably between 4*105 and 6*105

[0053] in which Na2O (FAu) denotes the quantity of Na2O provided by the FAU zeolite, Na2O (Naou) denotes the quantity of Na2O provided by the soda, SiO2(FAu) denotes the quantity of SiO2 provided by the FAU zeolite, and A12O3 (FAu) denotes the quantity of Al2 O3 provided by the FAU zeolite, until a homogeneous precursor gel is obtained;

[0054] ii) the hydrothermal treatment of said precursor gel obtained at the end of step i) at a temperature between 120°C and 220°C, for a duration between 12 hours and 7 days.

[0055] Advantageously, the SiO2 / Al2O3 molar ratio of the AEI zeolite obtained can be between 10 and 60, preferably between 12 and 50, limits included.

[0056] Advantageously, the zeolite of structural type FAU may have a SiO2 / Al2O3 molar ratio of between 10 and 60, preferably between 20 and 50, limits included, and a mass percentage of sodium in cationic form of less than 0.005%, preferably less than 0.0048%, in order to minimize the sodium content of the synthesis reaction mixture while facilitating zeolitization towards a zeolite of structural type AEI.

[0057] A ratio Na2O (NaoH) / (SiO2(FAu)) = 0 means that there is no sodium hydroxide added to the synthesis gel. In this case, the sodium content in the reaction mixture is solely due to the intrinsic sodium contribution of the starting FAU zeolite.

[0058] It may be advantageous to add seeds of a zeolite of structural type AEI to the reaction mixture during said step i) of the process of the invention in order to reduce the time required for the formation of the crystals of IZM-10 zeolite of structural type AEI and / or the total crystallization time. Said crystal seeds also promote the formation of said IZM-10 zeolite of structural type AEI to the detriment of impurities. Such seeds comprise crystallized solids, in particular crystals of a zeolite of structural type AEI. The crystal seeds are generally added in a proportion of between 0.01 and 10% of the total anhydrous mass of FAU zeolite used in the reaction mixture, said crystal seeds not being taken into account in the total mass of the SiO2 and Al2O3 sources.Said germs are also not taken into account for determining the composition of the reaction mixture and / or the gel, defined further, that is to say in the determination of the different molar ratios of the composition of the reaction mixture.

[0059] Step i) of mixing is carried out until a homogeneous mixture is obtained, preferably for a period greater than or equal to 15 minutes, preferably with stirring by any system known to those skilled in the art with low or high shear rate.

[0060] At the end of step i), a homogeneous precursor gel is obtained.

[0061] It may be advantageous to carry out a ripening of the reaction mixture before the hydrothermal crystallization during said step i) of the process of the invention in order to control the size of the crystals of the IZM-10 zeolite. Said ripening also promotes the formation of said IZM-10 zeolite to the detriment of impurities. The ripening of the reaction mixture during said step i) of the process of the invention may be carried out at room temperature or at a temperature between 20 and 100°C with or without stirring, for a duration advantageously between 30 min and 48 hours.

[0062] In accordance with step (ii) of the process according to the invention, the precursor gel obtained at the outcome of step i) is subjected to a hydrothermal treatment, preferably carried out at a temperature between 120°C and 220°C for a period between 12 hours and 7 days, until said IZM-10 zeolite of structural type AEI is formed.

[0063] The precursor gel is advantageously placed under hydrothermal conditions under an autogenous reaction pressure, optionally by adding gas, for example nitrogen, at a temperature preferably between 120°C and 220°C, preferably between 150°C and 200°C, even more preferably between 160°C and 195°C, until complete crystallization of a zeolite of structural type AEI.

[0064] The time required to obtain crystallization varies between 12 hours and 7 days, preferably between 12 hours and 6 days.

[0065] The reaction is generally carried out with stirring or without stirring, preferably with stirring. As stirring system, any system known to those skilled in the art can be used, for example, inclined blades with counterblades, stirring turbines, Archimedes screws.

[0066] At the end of the reaction, after carrying out said step ii) of the preparation process according to the invention, the solid phase formed from the IZM-10 zeolite is preferably filtered, washed and then dried. The drying is generally carried out at a temperature of between 20 and 150°C, preferably between 60 and 100°C, for a period of between 5 and 24 hours.

[0067] The dried zeolite can then be advantageously calcined. The calcined IZM-10 zeolite of structural type AEI 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.

[0068] Very advantageously, the process of the invention leads to the formation of an IZM-10 zeolite of AEI structural type, free from any other crystallized or amorphous phase. Said IZM-10 zeolite of AEI structural type, after the drying step, is then ready for subsequent steps such as calcination. For this step, all conventional methods known to those skilled in the art can be used.

[0069] The invention also relates to a zeolite of structural type AEI with a SiO2 / Al2O3 molar ratio of between 10 and 60, inclusive, at least partially protonated, i.e. comprising an Al2O3 / Na2O molar ratio of between 100 and 400, and preferably greater than 400, capable of being obtained by the preparation process described above.

[0070] The starting FAU structural type zeolite having a SiO2 / Al2O3 molar ratio of between 10 and 60, limits included, and a mass percentage of sodium in cationic form of less than 0.005%, can be obtained by any method known to those skilled in the art, such as by steam treatment and acid washes on a zeolite of structural type FAU with a SiO2 / Al2O3 molar ratio of less than 6.00. Among the sources of FAU with a SiO2 / Al2O3 molar ratio of between 10 and 60, inclusive, and a mass percentage of sodium in cationic form of less than 0.005%, we can cite the commercial zeolites CBV712, CBV720 and CBV760 produced by Zeolyst, the commercial zeolites HSZ-350HUA, HSZ-360HUA and HSZ-385HUA produced by TOSOH.

[0071] In accordance with the invention, a zeolite of structural type FAU having a molar ratio SiO2 (FAU) / A12O3 (FAu) of between 10 and 60, limits included, and a mass percentage of sodium in cationic form of less than 0.005%, is incorporated into the reaction mixture for the implementation of step (i) as a source of silicon and aluminum elements.

[0072] According to the invention, R is the organic nitrogen compound (6R,10S)-6,10-dimethyl-5-azoniaspiro[4,5]decane in its hydroxide form.

[0073] In accordance with the invention, Na2O(NaOH) denotes the quantity of Na2O provided by the sodium hydroxide. When the quantity Na2O(NaOH) is zero, this means that no source of sodium hydroxide is introduced into the reaction mixture of step i).

[0074] The loss on ignition of said IZM-10 zeolite of AEI structural type obtained after drying and before calcination is generally between 5 and 25% by weight. According to the invention, loss on ignition (LAI) means the percentage loss of mass undergone by a solid compound, a mixture of solid compounds or a paste, preferably in the case of the present invention by said IZM-10 zeolite prepared, during a heat treatment at 1000°C for 2 hours, in a static furnace (muffle furnace type), relative to the mass of the initial solid compound, mixture of solid compounds or paste, preferably in the case of the present invention relative to the mass of dried IZM-10 zeolite tested. Loss on ignition generally corresponds to the loss of solvent (such as water) contained in the solids, but also to the elimination of organic compounds contained in the mineral solid constituents.

[0075] The step of calcining the IZM-10 zeolite of AEI structural type obtained according to the process of the invention is preferably carried out at a temperature between 450 and 700°C for a duration between 2 and 20 hours.

[0076] The IZM-10 zeolite of structural type AEI obtained at the end of the calcination step is devoid of any organic species and in particular of the organic structuring agent R.

[0077] 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 structural type AEI. The purity obtained is advantageously greater than 98% and preferably greater than or equal to 99%, very preferably greater than or equal to 99.8% by weight. The solid obtained (IZM-10) has the diffraction diagram of X-rays including at least the lines present in [Fig.2]. 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 present in [Fig.2].

[0078] This diffraction diagram is obtained by radiocrystallographic analysis using a diffractometer using the classical powder method with Ka radiation, of copper (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(dhki) on dhki is calculated using the Bragg relation as a function of the absolute error A(20) assigned to the measurement of 20. An absolute error A(20) equal to ± 0.02° is commonly accepted in Angstroms (Â). Each of these values ​​must be assigned the measurement error A(dhki) between ± 0.6Â and ± 0.01Â.

[0079] The X-ray diffraction pattern of the IZM-10 zeolite of structural type AEI according to the invention comprises at least the lines with the values ​​of d^i given in Table 1, which presents the average values ​​of the d^i and relative intensities measured on an X-ray diffraction pattern of the calcined IZM-10 zeolite of structural type AEI according to the invention. In the column of d^i, the average values ​​of the inter-reticular distances in Angstroms (Â) are indicated. Each of these values ​​must be assigned the measurement error A(dhki) between ± 0.6Â and ± 0.01Â.

[0080] [Tables 1] 2 Ma C) àhkl. there) M ®L(Â) 9.241 FF 25.371 3.508 fi 10.690 8.268 f 26.066 3.416 fi 13.000 6.805 fi. 26.47 3.365 f 13.554 6.528 f. 27.317 3.262 fi 14.019 6.312 fi .28.002 3.184 f 14.811 5.976 fi 29.481 3.027 fi 16.179 5.474 I 29.841 2.992 fi 17.019 5.206 wf 30.19 2.958 fi. 17,313 5,118 M 30.605 2,919 H 19,179 4,624 fi 31,033 2,879 Et 19,762 4,489 fi. 31,335 2,852 F 20,158 4,402 fi 31,869 2,806 S 20,78 4,271 f 32,409 2,760 P 21,472 4,135 f 32,924 2,718 Et 22,103 4,018 fi 33,206 2,696 Et 22,609 3,930 fi. 33,986 2,636 And 23,288 3,817 fi 34,514 2,597 And 24.078 3,693 34,994 2.562 And

[0081]

[0082]

[0083] where FF = very strong; F = strong; m = medium; mf = medium weak; f = weak; ff = very weak. The relative intensity Irei is given in relation to a relative intensity scale where a value of 100 is assigned to the most intense line in the X-ray diffraction pattern: ff <15; 15 <f <30 ; 30 < mf <50 ; 50 <m < 65 ; 65 <F < 85 ; FF >85. 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. The process according to the invention makes it possible to obtain said AEI zeolite directly in protonated form (partially protonated or fully protonated). In the case where no no sodium hydroxide is added during the synthesis (ratio Na2O(NaoH) / (SiO2(FAU)) = 0), the process according to the invention makes it possible to directly obtain the fully protonated form of the IZM-10 zeolite of structural type AEI without it being necessary to carry out ion exchanges with solutions containing ammonium cations followed by calcination.

[0084] For the purposes of the present invention, the term “partially protonated” means an AEI zeolite comprising an Al2O3 / Na2O molar ratio of between 100 and 400, and “fully protonated” means an AEI zeolite comprising an Al2O3 / Na2O molar ratio of greater than 400.

[0085] The IZM-10 zeolite of AEI structural type obtained by the process of the invention can be used directly or after calcination 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. EXAMPLES

[0086] The invention is illustrated by the following examples which are in no way limiting.

[0087] Example 1: preparation of (6R,10S)-6,10-dimethyl-5-azoniaspiro[4,5]decane in its hydroxide form (structuring R).

[0088] In a 500 mL two-necked flask containing 140 mL of water, 5.68 g (0.142 mol) of sodium hydroxide and 30.66 g (0.142 mol, 16.82 mL) of 1,4-dibromobutane are added with stirring. The mixture is heated to reflux and 16.07 g (0.142 mol, 19.13 mL) of (2R,6S)-2,6-dimethylpiperidine are added dropwise over half an hour using a dropping funnel. After twelve hours of reflux, the mixture is cooled to 0°C and 70 mL of a cold 40% NaOH solution is added. The precipitate formed is extracted three times with 200 mL of chloroform. The extracted organic fractions are evaporated to a volume of 100 mL and the amine, in its bromide form, is precipitated with ether. The reaction yield is about 80-85%.

[0089] Molecular formula: CnH22NBr

[0090] Molar mass: 248 g / mol

[0091] 1H NMR (D2O, 400MHz, 25°C, δppm) for (6R,10S)-6,10-dimethyl-5-azoniaspiro[4,5]decane (cis-trans mixture): 1.30 (d, 6H, CH3); 1.55 (m, 4H, CH2); 1.70 (m, 2H, CH2); 2.10 (m, 4H,CH2); 3.28 (t, 2H, CH2-N); 3.50 (t, 2H, CH2-N); 3.64 (m, 2H, CH-N).

[0092] 18.9 g of Ag2O (0.08 mole, 99%, Aldrich) are added to a Teflon beaker of 250 mL containing 20 g of (6R,10S)-6,10-dimethyl-5-azoniaspiro[4,5]decane bromide (0.08 mol) and 100 mL of deionized water. The reaction medium is stirred away from light for 12 hours. The The mixture is then filtered and part of the water is evaporated using a rotary evaporator. The filtrate obtained is composed of an aqueous solution of (6R,10S)-6,10-dimethyl-5-azoniaspiro[4,5]decane in its hydroxide form (29.06% by weight). The determination of this species is carried out by proton NMR using formic acid as a standard.

[0093] Example 2: preparation of an IZM-10 zeolite of structural type AEI according to the invention.

[0094] 1.25 g of a zeolite of structural type FAU (CBV720, SiO2 / Al2O3= 33.34, Zeolyst, PAF = 14.34%, percentage of sodium in cationic form = 0.0045%) were mixed with 6.22 g of an aqueous solution of (6R,10S)-6,10-dimethyl-5-azoniaspiro[4,5]decane in its hydroxide form (29.06% by weight) prepared according to Example 1. 7.54 g of deionized water are added to the previous mixture, the preparation obtained is kept stirring for 10 minutes. The molar composition of the precursor gel is as follows: 1 SiO2: 0.03 A12O3: 0.58 R: 40 H2O, i.e. a SiO2 / Al2O3 ratio of 33.3. The precursor gel is then transferred, after homogenization, into an autoclave. The autoclave is closed and then heated for 140 hours at 180°C with stirring at 35 rpm using a rotating spit system. The solid obtained is filtered, washed with deionized water and then dried overnight at 100°C. The loss on ignition of the dried solid is 10%.The solid is then introduced into a muffle furnace where a calcination step is carried out: the calcination cycle includes a temperature rise of 1.5°C / min up to 200°C, a hold at 200°C maintained for 2 hours, a temperature rise of 1°C / min up to 550°C followed by a hold at 550°C maintained for 8 hours and then a return to room temperature.

[0095] The calcined solid product was analyzed by X-ray diffraction and identified as consisting of an IZM-10 zeolite of structural type AEI with a purity greater than 99% by weight. X-ray fluorescence analysis gives a molar ratio of SiO2 / Al2 O3 = 30.00 and a molar ratio of Al2O3 / Na2O = 450.

[0096] Example 3: preparation of an IZM-10 zeolite of AEI structural type according to the invention (with seeds).

[0097] 1.25 g of a zeolite of structural type FAU (CBV720, SiO2 / Al2O3= 33.34, Zeolyst, PAF = 14.34%, percentage of sodium in cationic form = 0.0045%) were mixed with 6.22 g of an aqueous solution of (6R,10S)-6,10-dimethyl-5-azoniaspiro[4,5]decane in its hydroxide form (29.06% by weight) prepared according to Example 1. 7.54 g of deionized water are added to the previous mixture, the preparation obtained is kept stirring for 10 minutes. In order to promote the formation of an IZM-10 zeolite of structural type AEI, 54 mg of seeds (5% relative to the mass of the CBV720 zeolite) of an IZM-10 zeolite of structural type AEI prepared according to Example 2 are added to the synthesis mixture and kept stirring for 5 minutes. The molar composition of the precursor gel is as follows: 1 SiO2: 0.03 Al2O3: 0.58 R: 40 H2O, i.e. a SiO2 / Al2O3 ratio of 33.3. The precursor gel is then transferred, after homogenization, into an autoclave. The autoclave is closed and then heated for 140 hours at 180°C with stirring at 35 rpm with a rotating spit system. The solid obtained is filtered, washed with deionized water and then dried overnight at 100°C. The loss on ignition of the dried solid is 10%. The solid is then introduced into a muffle furnace where a calcination step is carried out: the calcination cycle includes a temperature rise of 1.5°C / min up to 200°C, a hold at 200°C maintained for 2 hours, a temperature rise of 1°C / min up to 550°C followed by a hold at 550°C maintained for 8 hours and then a return to room temperature.

[0098] The calcined solid product was analyzed by X-ray diffraction and identified as consisting of an IZM-10 zeolite of structural type AEI with a purity greater than 99% by weight. X-ray fluorescence analysis gives a molar ratio of SiO2 / Al2 O3 = 29.20 and a molar ratio of Al2O3 / Na2O = 460.

[0099] Example 4: preparation of an IZM-10 zeolite of structural type AEI with a Na2O (Na0H) / (SiO2(FAu)) ratio of 0.15.

[0100] 1.33 g of a zeolite of structural type FAU (CBV720, SiO2 / Al2O3= 33.34, Zeolyst, PAF = 14.34%, percentage of sodium in cationic form = 0.0045%) were mixed with 2.304 g of an aqueous solution of (6R,10S)-6,10-dimethyl-5-azoniaspiro[4,5]decane in its hydroxide form (29.06% by weight) prepared according to Example 1. 11.15 g of deionized water and 0.212 g of NaOH are added to the previous mixture, the preparation obtained is kept stirring for 10 minutes. The molar composition of the precursor gel is as follows: 1 SiO2: 0.03 A12O3: 0.15 Na2O(NaOH): 0.20 R: 40 H2O, i.e. a SiO2 / Al2O3 ratio of 33.3. The precursor gel is then transferred, after homogenization, into an autoclave. The autoclave is closed and then heated for 48 hours at 180°C with stirring at 35 rpm using a rotating spit system. The solid obtained is filtered, washed with deionized water and then dried overnight at 100°C. The loss on ignition of the dried solid is 12%.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.

[0101] The calcined solid product was analyzed by X-ray diffraction and identified as consisting of an IZM-10 zeolite of structural type AEI with a purity greater than 99% by weight. X-ray fluorescence analysis gives a molar ratio SiO2 / Al2 O3 = 20.10 and a molar ratio Al2O3 / Na2O = 150.

[0102] Example 5: comparative, preparation of a zeolite with a Na2O(NaOH) / (SiO2 (fau)) ratio of 0.35.

[0103] 1.32 g of a zeolite of structural type FAU (CBV720, SiO2 / Al2O3= 33.34, Zeolyst, PAF = 14.34%s, percentage of sodium in cationic form = 0.0045%) were mixed with 2.30 g of an aqueous solution of (6R,10S)-6,10-dimethyl-5-azoniaspiro[4,5]decane in its hydroxide form (29.06% by weight) prepared according to Example 1. 11.16 g of deionized water and 0.493 g of NaOH are added to the previous mixture, the preparation obtained is kept stirring for 10 minutes. The molar composition of the precursor gel is as follows: 1 SiO2: 0.03 A12O3: 0.35 Na2O: 0.20 R: 40 H2O, i.e. a SiO2 / Al2O3 ratio of 33.3. The precursor gel is then transferred, after homogenization, into an autoclave. The autoclave is closed and then heated for 48 hours at 180°C with stirring at 35 rpm using a rotating spit system. The solid obtained is filtered, washed with deionized water and then dried overnight at 100°C. The loss on ignition of the dried solid is 12%.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.

[0104] The calcined solid product was analyzed by X-ray diffraction and identified as consisting of a mixture of zeolites of structural type AEI and MOR (mordenite).

Claims

Claims

1. Process for preparing an IZM-10 zeolite of AEI structural type comprising at least the following steps: i) mixing in an aqueous medium, a zeolite of FAU structural type having a SiO2(FAU) / Al2O3(FAU) molar ratio of between 10 and 60, limits included and a mass percentage of sodium in cationic form of less than 0.005%, of an organic nitrogen compound R, R being (6R,10S)-6,10-dimethyl-5-azoniaspiro[4,5]decane in its hydroxide form and optionally sodium hydroxide, the reaction mixture having the following molar composition: (SiO2 (fau)) / (Al2O3 (fau)) of between 10 and 60, preferably between 30 and 50 H2O / (SiO2 (fau)) of between 20 and 60, of preferably between 30 and 50 R / (SiO2(FAU)) between 0.05 and 0.70, preferably between 0.15 and 0.60 Na2O (NaOH) / (SiO2 (fau)) between 0 and 0.20, preferably between 0 and 0.15 Na2O (FAU) / (SiO2 (fau)) between 3.5*105 and 7*105,preferably between 4*105 and 6*105 in which Na2O (FAu) denotes the quantity of Na2O provided by the FAU zeolite, Na2O (NaOH) denotes the quantity of Na2O provided by the soda, SiO2 (FAu) denotes the quantity of SiO2 provided by the FAU zeolite, and A12O3 (fau) denotes the quantity of A12O3 provided by the FAU zeolite, until a homogeneous precursor gel is obtained; ii) the hydrothermal treatment of said precursor gel obtained at the end of step i) at a temperature of between 120°C and 220°C, for a period of between 12 hours and 7 days.,

2. Preparation process according to claim 1 in which the SiO2 / Al2O3 molar ratio of the AEI zeolite obtained is between 10 and 60, preferably between 12 and 50, limits included, and the Al2O3 / Na2O molar ratio of the AEI zeolite obtained is greater than 100, preferably greater than 400.

3. Preparation process according to one of claims 1 or 2 in which the zeolite of structural type FAU has a SiO2 / Al2 O3 molar ratio of between 20 and 50, limits included, and a mass percentage of sodium in cationic form of less than 0.0048%.

4. Process according to one of the preceding claims in which no sodium hydroxide is added to the reaction mixture of step i) (Na2O(NaOH) / (SiO 2 (fau)) = 0) and in which we directly obtain the fully protonated form of the IZM-10 zeolite of structural type AEI.

5. Process according to one of claims 1 to 4, in which crystalline seeds of a zeolite of structural type AEI are added to the reaction mixture of step i), preferably in an amount of between 0.01 and 10% by weight relative to the total mass of the sources of tetravalent and trivalent elements in anhydrous form present in said mixture, said crystalline seeds not being taken into account in the total mass of the sources of SiO2 and Al2O3.

6. Process according to one of claims 1 to 5 comprising a step of maturing the reaction mixture at a temperature between 20 and 100°C, with or without stirring, for a period between 30 minutes and 48 hours.

7. Process according to one of claims 1 to 6 in which the hydrothermal treatment of step ii) is carried out under autogenous pressure at a temperature between 120°C and 220°C, preferably between 150°C and 200°C, even more preferably between 160°C and 195°C, for a duration between 12 hours and 7 days, preferably between 12 hours and 6 days.

8. Process according to one of claims 1 to 7 in which the solid phase obtained at the end of step ii) is filtered, washed, and dried at a temperature between 20 and 150°C, preferably between 60 and 100°C, for a period between 5 and 24 hours to obtain a dried zeolite.

9. Process 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 of structural type AEI with a SiO2 / Al2O3 molar ratio of between 10 and 60, limits included, with a purity greater than or equal to 98% by weight, preferably greater than or equal to 99% by weight, very preferably greater than or equal to 99.8% by weight, in partially or totally protonated form, obtained by the process according to one of claims 1 to 9 and comprising the following significant X-ray diffraction lines: [Tables 1] 2 Ma C) tel 2 Ma O a®. (A) tel 9.530 9 241 FF 25.371 3.508 tt 10s690 8.268 f 26.066 3.416 a 13 0110 6.805 a 26.47 3.365 r 13.554 6.528 a 27.317 3.262 a 14.019 6.312 a 28.002 3.184 14.811 5.976 a 29.481 3.027 a. 16.179 5.474 i 29.841 2.992 a 17.019 5.206 te 30.19 2.958 a 17.313 5.118 te 30.605 2.919 Ef 19.179 4.624 a 31.033 2.879 s~.T 19762 4.489 a 31.335 2.852 F 20.158 4.402 a 31.869 2.806 Et 2078 4.271 i 3z.409 2.760 F 21.472 4.135 f 32 924 2.718 El 22.103 4.018 years 33.206 2.696 M 22.609 3.930 a 33.986 2.636 El 23.288 3.817 a 34.514 2.597 EX 24.078 3.693 M 34.994 2.562 El where FF = very strong; F = strong; m = medium; mf = medium weak; f = weak; ff = very weak; and the relative intensity Irei is given in relation to a relative intensity scale where a value of 100 is assigned to the most intense line in the X-ray diffraction pattern: ff <15; 15 <f <30 ; 30 < mf <50 ; 50 <m<65 ; 65 <F<85 ; FF > 85.

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