Small crystal SSZ-41, its synthesis and use
A method is disclosed for producing small crystal, high aluminum content zincoaluminosilicate crystalline materials having the SSZ-41 framework structure. The compositions made according to that method, as well as uses of the same, are also disclosed.
1. A method of synthesizing a zincoaluminosilicate molecular sieve having the framework structure of SSZ-41, the method comprising:
(1) forming a reaction mixture comprising:
(a) a FAU framework type zeolite;
(b) a source of zinc;
(c) a structure directing agent (Q) comprising 1,1′-(1,4-butanediyl)bis[4-aza-1-azoniabicyclo[2.2.2]octane] dications;
(d) a source of lithium;
(e) a source of hydroxide ions;
(f) water; and
(g) seeds; and
(2) subjecting the reaction mixture to crystallization conditions sufficient to form crystals of the zincoaluminosilicate molecular sieve;
wherein the reaction mixture is free or essentially free of sodium.
2. The method of claim 1 , wherein the reaction mixture has a composition, in terms of molar ratios, as follows:
SiO 2 /Al 2 O 3
30 to <100
SiO 2 /ZnO
15 to 75
Q/SiO 2
0.10 to 0.50
Li/SiO 2
0.05 to 0.35
OH/SiO 2
0.10 to 0.50
H 2 O/SiO 2
10 to 60.
3. The method of claim 1 , wherein the reaction mixture has a composition, in terms of molar ratios, as follows:
SiO 2 /Al 2 O 3
50 to 90
SiO 2 /ZnO
20 to 40
Q/SiO 2
0.15 to 0.40
Li/SiO 2
0.10 to 0.30
OH/SiO 2
0.15 to 0.40
H 2 O/SiO 2
15 to 45.
4. The method of claim 1 , wherein the FAU framework type zeolite is zeolite Y.
5. The method of claim 1 , wherein the source of zinc comprises a zinc salt of organic or inorganic acid, a zinc-exchanged FAU framework type zeolite, or any combination thereof.
6. The method of claim 1 , wherein the source of lithium comprises lithium hydroxide, a lithium halide, or any combination thereof.
7. The method of claim 1 , wherein the seeds comprise a molecular sieve having the framework structure of SSZ-41.
8. The method of claim 1 , wherein the reaction mixture comprises from 0.1 to 20 wt. % of seeds relative to total weight of SiO 2 in the reaction mixture.
9. The method of claim 1 , wherein the crystallization conditions heating the reaction mixture under autogenous pressure at a temperature in a range of from 100° C. to 200° C. for a time of from 1 day to 14 days.