Process for preparing an IZM-2 zeolite in the presence of a mixture of nitrogenous organic structuring agents in hydroxide form and of bromide and of an alkali metal chloride

Abstract

The invention relates to a process for preparing a synthetic IZM-2 zeolite, which consists in performing a hydrothermal treatment of an aqueous gel containing a source of silicon and a source of amorphous aluminium, two nitrogenous or structuring organic compounds including two quaternary ammonium functions, 1,6-bis(methylpiperidinium)hexane dihydroxide and 1,6-bis(methylpiperidinium)hexane dibromide, used as a mixture, in combination with a source of a specific alkali metal chloride M (preferably NaCl), the aqueous gel not comprising any source of at least one fluoride anion.

Claims

1. A process comprising preparing an IZM-2 zeolite, by at least the following: i) mixing, in aqueous medium, at least one source of at least one tetravalent element X in oxide form XO.sub.2, at least one source of at least one trivalent element in oxide form Y.sub.2O.sub.3, nitrogenous organic compounds R(OH).sub.2 and R(Br).sub.2, R(OH).sub.2 being 1,6-bis(methylpiperidinium)hexane dihydroxide, and R(Br).sub.2 being 1,6-bis(methylpiperidinium)hexane dibromide, and at least one alkali metal chloride as a source of at least one alkali metal M of valency n, n being an integer greater than or equal to 1, M being lithium, potassium, sodium, cesium or a mixture of at least two of these metals, and in the absence of at least one source of at least one fluoride anion termed BF, BF being hydrofluoric acid in aqueous solution or fluorine salts in which B is a NH.sub.4.sup.+, Na.sup.+, K.sup.+ or Li.sup.+ cation, or a mixture of at least two of these salts, the reaction mixture having the following molar composition: XO.sub.2/Y.sub.2O.sub.3 70 and 350, H.sub.2O/XO.sub.2 1 and 100, R(OH).sub.2/XO.sub.2 0.006 to 0.25, R(Br).sub.2/XO.sub.2 0.006 to 0.25, M.sub.1/nCl/XO.sub.2 0.005 to 0.5, with X being silicon, germanium, titanium or a mixture of at least two of these tetravalent elements, Y being aluminium, boron, iron, indium and gallium, or a mixture of at least two of these trivalent elements, until a homogeneous precursor gel is obtained; ii) hydrothermal treatment of said precursor gel obtained on conclusion of i) at a temperature of 120° C. to 220° C., for a time of between 1 day and 8 days.

2. The process according to claim 1, in which the mixture of i) also further comprises one or more tetravalent elements X other than silicon: germanium or titanium and/or one or more trivalent elements Y, other than aluminium: iron, boron, indium or gallium.

3. The process according to claim 1, in which the reaction mixture from i) has the following molar composition: XO.sub.2/Y.sub.2O.sub.3 80 and 300 H.sub.2O/XO.sub.2 5 and 50 R(OH).sub.2/XO.sub.2 0.01 to 0.15 R(Br).sub.2/XO.sub.2 0.01 to 0.15 M.sub.1/nCl/XO.sub.2 0.02 to 0.3; X, Y, R and M having the abovementioned meaning.

4. The process according to claim 1, in which M is sodium.

5. The process according to claim 1, in which the mixture of i) is prepared in the absence of a fluorine salt BF in which B is the NH.sub.4.sup.+ cation.

6. The process according to claim 1, in which seed crystals of an IZM-2 zeolite are added to the reaction mixture from i) in an amount of 0.01% to 10% of the total mass of the sources of said tetravalent and trivalent element(s) in anhydrous form used in the reaction mixture, said seed crystals not being taken into account in the total mass of the sources of the tetravalent and trivalent elements.

7. The process according to claim 1, in which i) comprises maturing the reaction mixture obtained at a temperature of 20 to 100° C., with or without stirring, for a time of 30 minutes to 48 hours.

8. The process according to claim 1, in which the hydrothermal treatment of ii) is performed under autogenous pressure at a temperature of 150° C. to 195° C.

9. The process according to claim 8, in which the solid phase obtained on conclusion of ii) may be filtered, washed and dried at a temperature of 20 to 150° C., for a time of 5 to 24 hours to obtain a dried zeolite.

10. The process according to claim 9, in which the dried zeolite is then calcined at a temperature of 450 to 700° C. for a time of 2 to 20 hours, the calcination optionally being preceded by a gradual temperature increase.

11. The process according to claim 1, in which the hydrothermal treatment of ii) is performed for a time of between 1 day and 7 days.

12. The process according to claim 11, in which the hydrothermal treatment is performed for a time of 2 to 6 days.

13. The process according to claim 12, in which the hydrothermal treatment is performed for a time of 2 to 5 days.

14. The process according to claim 13, in which the hydrothermal treatment is performed for a time of 2 to 4.5 days.

Description

LIST OF FIGURES

(1) FIG. 1 represents the chemical formula of the nitrogenous organic compounds chosen as structuring agent in the synthetic process according to the invention.

(2) FIG. 2 represents the X-ray diffraction pattern of the IZM-2 zeolite obtained according to Example 6.

(3) FIG. 3 represents the X-ray diffraction pattern of the ZSM-5 zeolite obtained according to Comparative Example 8.

(4) Other characteristics and advantages of the synthetic process according to the invention will become apparent on reading the following description of non-limiting exemplary embodiments with reference to the appended figures described below.

(5) Without further elaboration, it is believed that one skilled in the art can, using the preceding description, utilize the present invention to its fullest extent. The preceding preferred specific embodiments are, therefore, to be construed as merely illustrative, and not limitative of the remainder of the disclosure in any way whatsoever.

(6) In the foregoing and in the examples, all temperatures are set forth uncorrected in degrees Celsius and, all parts and percentages are by weight, unless otherwise indicated.

(7) The entire disclosures of all applications, patents and publications, cited herein and of corresponding application No. FR 1910620, filed Sep. 26, 2019 are incorporated by reference herein.

EXAMPLES

Example 1

Preparation of 1,6-bis(methylpiperidinium)hexane dibromide [R(Br).SUB.2.]

(8) 50 g of 1,6-dibromohexane (0.20 mol, 99%, Alfa Aesar) are placed in a 1 L round-bottomed flask containing 50 g of N-methylpiperidine (0.51 mol, 99%, Alfa Aesar) and 200 mL of ethanol. The reaction medium is stirred at reflux for 5 hours. The mixture is then cooled to room temperature and then filtered. The mixture is poured into 300 mL of cold diethyl ether and the precipitate formed is then filtered off and washed with 100 mL of diethyl ether. The solid obtained is recrystallized from an ethanol/ether mixture. The solid obtained is dried under vacuum for 12 hours. 71 g of a white solid are obtained (i.e. a yield of 80%).

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

Example 2

Preparation of 1,6-bis(methylpiperidinium)hexane dihydroxide [R(OH).SUB.2.]

(10) 18.9 g of Ag.sub.2O (0.08 mol, 99%, Aldrich) are placed in a 250 ml Teflon beaker containing 30 g of the structuring agent 1,6-bis(methylpiperidinium) dibromide (0.07 mol) prepared according to Example 1 and 100 ml of deionized water. The reaction medium is stirred for 12 hours in the absence of light. The mixture is then filtered. The filtrate obtained is composed of an aqueous solution of 1,6-bis(methylpiperidinium)hexane dihydroxide. Assay of this species is performed by proton NMR using formic acid as standard.

Example 3

Preparation of an IZM-2 Solid According to the Invention

(11) 2.064 g of an aqueous solution of 1,6-bis(methylpiperidinium)hexane dibromide (21.5% by weight) prepared according to Example 1 and 1.738 g of an aqueous solution of 1,6-bis(methylpiperidinium)hexane dihydroxide (18.36% by weight) prepared according to Example 2 are mixed with 1.622 g of deionized water. 0.426 g of sodium chloride (solid, purity of 99% by weight, Alfa Aesar) is added to the preceding mixture, and the preparation obtained is kept stirring for 10 minutes. 0.009 g of amorphous aluminium hydroxide gel (amorphous Al(OH).sub.3 gel, 58.55% Al.sub.2O.sub.3, Merck) is then incorporated and the synthetic gel is kept stirring for 15 minutes. Finally, 1.814 g of colloidal silica (Ludox HS40, 40% by weight, Aldrich) are incorporated into the synthesis mixture, which is kept stirring for 30 minutes to evaporate off the solvent until the desired precursor gel composition is obtained, i.e. a molar composition of the following mixture: 60 SiO.sub.2:0.25 Al.sub.2O.sub.3:5 R(Br).sub.2:5 R(OH).sub.2:9.6 NaCl:1770 H.sub.2O, i.e. an SiO.sub.2/Al.sub.2O.sub.3 ratio of 240. The precursor gel is then transferred, after homogenization, into an autoclave. The autoclave is closed and then heated for 4 days at 170° C. with stirring at 32 rpm with a rotary spit system. The crystalline product obtained is filtered off, washed with deionized water and then dried overnight at 100° C. The solid is then introduced into a muffle furnace where a calcination step is performed: the calcination cycle comprises an increase in temperature of 1.5° C./minute up to 200° C., a steady stage at 200° C. maintained for 2 hours, an increase in temperature of 1° C./minute up to 550° C., followed by a steady stage at 550° C. maintained for 8 hours, then return to room temperature.

(12) The calcined solid product was analysed by X-ray diffraction and identified as consisting of an IZM-2 zeolite with a purity of greater than 99.8%.

Example 4

Preparation of an IZM-2 Solid According to the Invention

(13) 2.079 g of an aqueous solution of 1,6-bis(methylpiperidinium)hexane dibromide (21.5% by weight) prepared according to Example 1 and 1.746 g of an aqueous solution of 1,6-bis(methylpiperidinium)hexane dihydroxide (18.36% by weight) prepared according to Example 2 are mixed with 1.811 g of deionized water. 0.219 g of sodium chloride (solid, purity of 99% by weight, Alfa Aesar) is added to the preceding mixture, and the preparation obtained is kept stirring for 10 minutes. 0.009 g of amorphous aluminium hydroxide gel (amorphous Al(OH).sub.3 gel, 58.55% Al.sub.2O.sub.3, Merck) is then incorporated and the synthetic gel is kept stirring for 15 minutes. Finally, 1.823 g of colloidal silica (Ludox HS40, 40% by weight, Aldrich) are incorporated into the synthesis mixture, which is kept stirring for 30 minutes to evaporate off the solvent until the desired precursor gel composition is obtained, i.e. a molar composition of the following mixture: 60 SiO.sub.2:0.25 Al.sub.2O.sub.3:5 R(Br).sub.2:5 R(OH).sub.2:4.8 NaCl:1770 H.sub.2O, i.e. an SiO.sub.2/Al.sub.2O.sub.3 ratio of 240. The precursor gel is then transferred, after homogenization, into an autoclave. The autoclave is closed and then heated for 4 days at 170° C. with stirring at 32 rpm with a rotary spit system. The crystalline product obtained is filtered off, washed with deionized water and then dried overnight at 100° C. The solid is then introduced into a muffle furnace where a calcination step is performed: the calcination cycle comprises an increase in temperature of 1.5° C./minute up to 200° C., a steady stage at 200° C. maintained for 2 hours, an increase in temperature of 1° C./minute up to 550° C., followed by a steady stage at 550° C. maintained for 8 hours, then return to room temperature.

(14) The calcined solid product was analysed by X-ray diffraction and identified as consisting of an IZM-2 zeolite with a purity of greater than 99.8%.

Example 5

Preparation of an IZM-2 Solid According to the Invention

(15) 1.586 g of an aqueous solution of 1,6-bis(methylpiperidinium)hexane dibromide (21.5% by weight) prepared according to Example 1 and 1.336 g of an aqueous solution of 1,6-bis(methylpiperidinium)hexane dihydroxide (18.36% by weight) prepared according to Example 2 are mixed with 2.537 g of deionized water. 0.438 g of sodium chloride (solid, purity of 99% by weight, Alfa Aesar) is added to the preceding mixture, and the preparation obtained is kept stirring for 10 minutes. 0.009 g of amorphous aluminium hydroxide gel (amorphous Al(OH).sub.3 gel, 58.55% Al.sub.2O.sub.3, Merck) is then incorporated and the synthetic gel is kept stirring for 15 minutes. Finally, 1.884 g of colloidal silica (Ludox HS40, 40% by weight, Aldrich) are incorporated into the synthesis mixture, which is kept stirring for 30 minutes to evaporate off the solvent until the desired precursor gel composition is obtained, i.e. a molar composition of the following mixture: 60 SiO.sub.2:0.25 Al.sub.2O.sub.3:3.75 R(Br).sub.2:3.75 R(OH).sub.2:9.6 NaCl:1770 H.sub.2O, i.e. an SiO.sub.2/Al.sub.2O.sub.3 ratio of 240. The precursor gel is then transferred, after homogenization, into an autoclave. The autoclave is closed and then heated for 3 days at 170° C. with stirring at 32 rpm with a rotary spit system. The crystalline product obtained is filtered off, washed with deionized water and then dried overnight at 100° C. The solid is then introduced into a muffle furnace where a calcination step is performed: the calcination cycle comprises an increase in temperature of 1.5° C./minute up to 200° C., a steady stage at 200° C. maintained for 2 hours, an increase in temperature of 1° C./minute up to 550° C., followed by a steady stage at 550° C. maintained for 8 hours, then return to room temperature.

(16) The calcined solid product was analysed by X-ray diffraction and identified as consisting of an IZM-2 zeolite with a purity of greater than 99.8%.

Example 6

Preparation of an IZM-2 Solid According to the Invention

(17) 2.064 g of an aqueous solution of 1,6-bis(methylpiperidinium)hexane dibromide (21.5% by weight) prepared according to Example 1 and 1.737 g of an aqueous solution of 1,6-bis(methylpiperidinium)hexane dihydroxide (18.36% by weight) prepared according to Example 2 are mixed with 1.619 g of deionized water. 0.432 g of sodium chloride (solid, purity of 99% by weight, Alfa Aesar) is added to the preceding mixture, and the preparation obtained is kept stirring for 10 minutes. 0.012 g of amorphous aluminium hydroxide gel (amorphous Al(OH).sub.3 gel, 58.55% Al.sub.2O.sub.3, Merck) is then incorporated and the synthetic gel is kept stirring for 15 minutes. Finally, 1.807 g of colloidal silica (Ludox HS40, 40% by weight, Aldrich) are incorporated into the synthesis mixture, which is kept stirring for 30 minutes to evaporate off the solvent until the desired precursor gel composition is obtained, i.e. a molar composition of the following mixture: 60 SiO.sub.2:0.35 Al.sub.2O.sub.3:5 R(Br).sub.2:5 R(OH).sub.2:9.6 NaCl:1770 H.sub.2O, i.e. an SiO.sub.2/Al.sub.2O.sub.3 ratio of 171.4. The precursor gel is then transferred, after homogenization, into an autoclave. The autoclave is closed and then heated for 3 days at 170° C. with stirring at 32 rpm with a rotary spit system. The crystalline product obtained is filtered off, washed with deionized water and then dried overnight at 100° C. The solid is then introduced into a muffle furnace where a calcination step is performed: the calcination cycle comprises an increase in temperature of 1.5° C./minute up to 200° C., a steady stage at 200° C. maintained for 2 hours, an increase in temperature of 1° C./minute up to 550° C., followed by a steady stage at 550° C. maintained for 8 hours, then return to room temperature.

(18) The calcined solid product was analysed by X-ray diffraction and identified as consisting of an IZM-2 zeolite with a purity of greater than 99.8%. The diffraction pattern produced for the calcined IZM-2 microporous solid is given in FIG. 2.

Example 7

Preparation of an IZM-2 Solid According to the Invention

(19) 2.046 g of an aqueous solution of 1,6-bis(methylpiperidinium)hexane dibromide (21.5% by weight) prepared according to Example 1 and 1.726 g of an aqueous solution of 1,6-bis(methylpiperidinium)hexane dihydroxide (18.36% by weight) prepared according to Example 2 were mixed with 1.422 g of deionized water. 0.676 g of sodium chloride (solid, purity of 99% by weight, Alfa Aesar) is added to the preceding mixture, and the preparation obtained is kept stirring for 10 minutes. 0.021 g of amorphous aluminium hydroxide gel (amorphous Al(OH).sub.3 gel, 58.55% Al.sub.2O.sub.3, Merck) is then incorporated and the synthetic gel is kept stirring for 15 minutes. Finally, 1.814 g of colloidal silica (Ludox HS40, 40% by weight, Aldrich) are incorporated into the synthesis mixture, which is kept stirring for 30 minutes to evaporate off the solvent until the desired precursor gel composition is obtained, i.e. a molar composition of the following mixture: 60 SiO.sub.2:0.6 Al.sub.2O.sub.3:5 R(Br).sub.2:5 R(OH).sub.2:15 NaCl:1770 H.sub.2O, i.e. an SiO.sub.2/Al.sub.2O.sub.3 ratio of 100. The precursor gel is then transferred, after homogenization, into an autoclave. The autoclave is closed and then heated for 3 days at 170° C. with stirring at 32 rpm with a rotary spit system. The crystalline product obtained is filtered off, washed with deionized water and then dried overnight at 100° C. The solid is then introduced into a muffle furnace where a calcination step is performed: the calcination cycle comprises an increase in temperature of 1.5° C./minute up to 200° C., a steady stage at 200° C. maintained for 2 hours, an increase in temperature of 1° C./minute up to 550° C., followed by a steady stage at 550° C. maintained for 8 hours, then return to room temperature.

(20) The calcined solid product was analysed by X-ray diffraction and identified as consisting of an IZM-2 zeolite with a purity of greater than 99.8%.

Comparative Example 8

Preparation of an IZM-2 Solid not in Accordance with the Invention

(21) Example 8 is not in accordance with the invention since the process is performed in fluorinated medium.

(22) 2.045 g of an aqueous solution of 1,6-bis(methylpiperidinium)hexane dibromide (21.5% by weight) prepared according to Example 1 and 1.755 g of an aqueous solution of 1,6-bis(methylpiperidinium)hexane dihydroxide (18.36% by weight) prepared according to Example 2 are mixed with 0.867 g of deionized water. 0.421 g of sodium chloride (solid, purity of 99% by weight, Alfa Aesar) is added to the preceding mixture, and the preparation obtained is kept stirring for 10 minutes. 0.012 g of amorphous aluminium hydroxide gel (amorphous Al(OH).sub.3 gel, 58.55% Al.sub.2O.sub.3, Merck) is then incorporated and the synthetic gel is kept stirring for 15 minutes. 1.799 g of colloidal silica (Ludox HS40, 40% by weight, Aldrich) are incorporated into the mixture, which is kept stirring for 15 minutes. Finally, 0.831 g of aqueous ammonium fluoride solution (10% by weight) is incorporated into the synthetic mixture, which is kept stirring for 30 minutes to evaporate off the solvent until the composition of the desired precursor gel is obtained, i.e. a molar composition of the following mixture: 60 SiO.sub.2:0.35 Al.sub.2O.sub.3:5 R(Br).sub.2:5 R(OH).sub.2:9.6 NaCl:1770 H.sub.2O:10 NH.sub.4F, i.e. an SiO.sub.2/Al.sub.2O.sub.3 ratio of 171. The precursor gel is then transferred, after homogenization, into an autoclave. The autoclave is closed and then heated for 14 days at 170° C. with stirring at 32 rpm with a rotary spit system. The crystalline product obtained is filtered off, washed with deionized water and then dried overnight at 100° C. The solid is then introduced into a muffle furnace where a calcination step is performed: the calcination cycle comprises an increase in temperature of 1.5° C./minute up to 200° C., a steady stage at 200° C. maintained for 2 hours, an increase in temperature of 1° C./minute up to 550° C., followed by a steady stage at 550° C. maintained for 8 hours, then return to room temperature.

(23) The calcined solid product was analysed by X-ray diffraction and identified as consisting of a zeolite of MFI framework type with a purity of greater than 95% by weight. In this case, the IZM-2 zeolite is not obtained.

(24) The preceding examples can be repeated with similar success by substituting the generically or specifically described reactants and/or operating conditions of this invention for those used in the preceding examples.

(25) From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions.