Process for preparation of a MEL-structural-type zeolite
View Patent ↗A process for preparation of a MEL-structural-type zeolite that comprises at least the following stages: i) the mixture, in aqueous medium, of at least one source of at least one tetravalent element and at least one nitrogen-containing organic radical of the formula: in which n represents the methylene group number (CH 2 ) and is equal to 6 or 7, and R1 and R2 represent alkyl groups that have 2 to 7 carbon atoms, ii) the hydrothermal treatment of said mixture until said MEL-structural-type zeolite is formed, is described.
1. A process for preparation of a MEL-structural-type zeolite that comprises at least the following stages:
i) providing a mixture comprising, in aqueous medium at least one source of at least one tetravalent element X and at least one nitrogen-containing organic radical of formula (I)
wherein n represents 6 or 7 methylene groups (CH 2 ) and R1 and R2 represent alkyl groups C a H 2a+1 , wherein a is between 2 and 7 inclusive,
ii) subjecting said mixture to hydrothermal treatment under sufficient conditions to form said MEL-structural-type zeolite.
2. A process for preparation according to claim 1 , wherein said nitrogen-containing organic radical of formula (I) is an N,N-dipropylhexamethylene iminium cation or an N,N-dibutylhexamethylene iminium cation.
3. A process for preparation according to claim 1 wherein the tetravalent element X is silicon, germanium, titanium or a mixture of at least two of said tetravalent elements.
4. A process for preparation according to claim 3 , wherein said tetravalent element X is silicon.
5. A process for preparation according to claim 1 , wherein at least one source of at least one trivalent element Y is incorporated in the mixture of said stage i).
6. A process for preparation according to claim 5 , wherein said element Y is aluminum.
7. A process for preparation according to claim 5 , wherein at least one alkaline metal and/or alkaline-earth metal M is incorporated in the mixture of said stage i).
8. A process for preparation according to claim 7 , wherein fluoride anion is incorporated in the mixture for the implementation of said stage i).
9. A process for preparation according to claim 8 , wherein said hydrothermal treatment according to said stage ii) is carried out at a temperature of between 80° C. and 200° C.
10. A process for preparation according to claim 5 , wherein fluoride anion is incorporated in the mixture for the implementation of said stage i).
11. A process for preparation according to claim 1 , wherein at least one alkaline metal and/or alkaline-earth metal M is incorporated in the mixture of said stage i).
12. A process for preparation according to claim 11 , wherein said metal M is sodium.
13. A process for preparation according to claim 1 , wherein fluoride anion is incorporated in the mixture of said stage i).
14. A process for preparation according to claim 1 , wherein the mixture in stage (i) has a molar composition expressed by the formula XO 2 :vYO b :wM 2 / m O:xF − :y H 2 O:zR + , in which v is between 0 and 0.5 inclusive, w is between 0 and 1 inclusive, x is between 0 and 1 inclusive, y is between 1 and 100 inclusive, z is between 0.04 and 2 inclusive, b is between 1 and 3 inclusive (wherein b is a whole number or a rational number), and m is equal to 1 or 2, and wherein R + is a nitrogen-containing, cationic organic radical of formula (I), wherein Y is at least one trivalent element, M is at least one alkaline metal and/or alkaline-earth metal and, R + is at least one nitrogen-containing organic radical of formula (I), and wherein v, w, x, y and z respectively represent the number of mols of YO b , M 2/m O, F − , H 2 O and R + .
15. A process for preparation according to claim 14 , wherein said hydrothermal treatment according to said stage ii) is carried out at a temperature of between 80° C. and 200° C.
16. A process according to claim 14 , wherein
v is between 0.005 and 0.3 inclusive
w is between 0.05 and 0.5 inclusive
x is between 0.1 and 0.8 inclusive
y is between 1.0 and 70 inclusive
z is between 0.1 and 0.8 inclusive
b is between 1 and 3 inclusive
m is 1 or 2.
17. A process for preparation according to claim 1 , further comprising forming a reaction mixture according to said stage i).
18. A process according to claim 17 , further comprising adding nuclei of a MEL-structural type zeolite to the reaction mixture.
19. A process for preparation according to claim 1 , wherein said hydrothermal treatment according to said stage ii) is carried out at a temperature of between 80° C. and 200° C.
20. A process for preparation according to claim 1 , wherein a solid phase is formed by the MEL-structural-type zeolite, obtained at the end of said stage ii), which is then filtered, washed, and dried.