Molecular sieve SSZ-91
A family of new crystalline molecular sieves designated SSZ-91 is disclosed. Molecular sieve SSZ-91 is structurally similar to sieves falling within the ZSM-48 family of molecular sieves, and is characterized as: (1) having a low degree of faulting, (2) a low aspect ratio that inhibits hydrocracking as compared to conventional ZSM-48 materials having an aspect ratio of greater than 8, and (3) is substantially phase pure.
1. A molecular sieve belonging to the ZSM-48 family of zeolites, wherein the molecular sieve comprises:
a silicon oxide to aluminum oxide mole ratio of 40 to 200,
at least 70% polytype 6 of the total ZSM-48 family material present in the product, and
an additional EUO framework molecular sieve phase in an amount of between 0 and 3.5 percent by weight of the total product; and
wherein the molecular sieve has a morphology characterized as polycrystalline aggregates comprising crystallites collectively having an average aspect ratio of between 1 and 8.
2. The molecular sieve of claim 1 , wherein the molecular sieve has, in its as-synthesized form, an X-ray diffraction pattern substantially as shown in the following Table:
2-Theta
d-spacing (nm)
Relative Intensity(*)
7.55 ± 0.20
1.170
W
8.71 ± 0.20
1.015
W
12.49 ± 0.20
0.708
W
15.12 ± 0.20
0.586
W
21.18 ± 0.20
0.419
VS
22.82 ± 0.20
0.390
VS
24.62 ± 0.20
0.361
W
26.39 ± 0.20
0.337
W
29.03 ± 0.20
0.307
W
31.33 ± 0.20
0.285
W
(*)Relative intensity scale in which the strongest line in the X-ray diffraction pattern is assigned a value of 100, wherein: W = weak (>0 to 20); M = medium (>20 to 40); S = strong (>40 to 60); VS = very strong (>60 to 100).
3. The molecular sieve of claim 1 , wherein the molecular sieve has a silicon oxide to aluminum oxide mole ratio of 70 to 160.
4. The molecular sieve of claim 3 , wherein the molecular sieve comprises at least 80% polytype 6 of the total ZSM-48 family material present in the product.
5. The molecular sieve of claim 3 , wherein the molecular sieve comprises at least 90% polytype 6 of the total ZSM-48 family material present in the product.
6. The molecular sieve of claim 3 , wherein the crystallites collectively have an average aspect ratio of between 1 and 5.
7. The molecular sieve of claim 3 , wherein the crystallites collectively have an average aspect ratio of between 1 and 3.
8. The molecular sieve of claim 3 , wherein the molecular sieve comprises between 0.1 and 2 wt. % EUO framework molecular sieve.
9. The molecular sieve of claim 3 , wherein the molecular sieve comprises between 0.1 and 1 wt. % EUO framework molecular sieve.
10. The molecular sieve of claim 3 , wherein the molecular sieve comprises between 0.1 and 2 wt. % EU-1.
11. The molecular sieve of claim 3 , wherein the molecular sieve comprises between 0.1 and 1 wt. % EU-1.
12. The molecular sieve of claim 1 , wherein the molecular sieve has a silicon oxide to aluminum oxide mole ratio of 80 to 140.
13. The molecular sieve of claim 12 , wherein the molecular sieve comprises at least 80% polytype 6 of the total ZSM-48 family material present in the product.
14. The molecular sieve of claim 12 , wherein the molecular sieve comprises at least 90% polytype 6 of the total ZSM-48 family material present in the product.
15. The molecular sieve of claim 12 , wherein the crystallites collectively have an average aspect ratio of between 1 and 5.
16. The molecular sieve of claim 12 , wherein the crystallites collectively have an average aspect ratio of between 1 and 3.
17. The molecular sieve of claim 12 , wherein the molecular sieve comprises between 0.1 and 2 wt. % EUO framework molecular sieve.
18. The molecular sieve of claim 12 , wherein the molecular sieve comprises between 0.1 and 1 wt. % EUO framework molecular sieve.
19. The molecular sieve of claim 12 , wherein the molecular sieve comprises between 0.1 and 2 wt. % EU-1.
20. The molecular sieve of claim 12 , wherein the molecular sieve comprises between 0.1 and 1 wt. % EU-1.
21. The molecular sieve of claim 1 , wherein the molecular sieve comprises at least 80% polytype 6 of the total ZSM-48 family material present in the product.
22. The molecular sieve of claim 1 , wherein the molecular sieve comprises at least 90% polytype 6 of the total ZSM-48 family material present in the product.
23. The molecular sieve of claim 1 , wherein the crystallites collectively have an average aspect ratio of between 1 and 5.
24. The molecular sieve of claim 1 , wherein the crystallites collectively have an average aspect ratio of between 1 and 3.
25. The molecular sieve of claim 1 , wherein the molecular sieve comprises between 0.1 and 2 wt. % EUO framework molecular sieve.
26. The molecular sieve of claim 1 , wherein the molecular sieve comprises between 0.1 and 1 wt. % EUO framework molecular sieve.
27. A method of preparing the molecular sieve of claim 1 , comprising:
(a) preparing a reaction mixture containing:
at least one source of silicon,
at least one source of aluminum,
at least one source of an element selected from Groups 1 and 2 of the Periodic Table,
hydroxide ions,
hexamethonium cations, and
water; and
(b) subjecting the reaction mixture to crystallization conditions sufficient to form crystals of the molecular sieve.
28. The method of claim 27 , wherein the molecular sieve is SSZ-91 and has, in its as-synthesized form, the X-ray diffraction pattern substantially as shown in the following Table:
2-Theta
d-spacing (nm)
Relative Intensity(*)
7.55 ± 0.20
1.170
W
8.71 ± 0.20
1.015
W
12.49 ± 0.20
0.708
W
15.12 ± 0.20
0.586
W
21.18 ± 0.20
0.419
VS
22.82 ± 0.20
0.390
VS
24.62 ± 0.20
0.361
W
26.39 ± 0.20
0.337
W
29.03 ± 0.20
0.307
W
31.33 ± 0.20
0.285
W
(*)Relative intensity scale in which the strongest line in the X-ray diffraction pattern is assigned a value of 100, wherein: W = weak (>0 to 20); M = medium (>20 to 40); S = strong (>40 to 60); VS = very strong (>60 to 100).
29. The method of claim 27 , wherein the molecular sieve is prepared from a reaction mixture comprising, in terms of mole ratios, the following:
SiO 2 /Al 2 O 3
50-220
M/SiO 2
0.05-1.0
Q/SiO 2
0.01-0.2
OH/SiO 2
0.05-0.4
H 2 O/SiO 2
3-100
wherein M is selected from the group consisting of elements from Groups 1 and 2 of the Periodic Table; and Q is a hexamethonium cation.
30. The method of claim 27 , wherein the molecular sieve is prepared from a reaction mixture comprising, in terms of mole ratios, the following:
SiO 2 /Al 2 O 3
85-180
M/SiO 2
0.1-0.8
Q/SiO 2
0.02-0.1
OH/SiO 2
0.10-0.3
H 2 O/SiO 2
10-50
wherein M is selected from the group consisting of elements from Groups 1 and 2 of the Periodic Table; and Q is a hexamethonium cation.