AFI

SSZ-24

Si(100)

Contributed by S. I. Zones and L T. Yuen

Verified by A. Bell and C. Gittleman, by A. Cheetham, and by R Lobo and D. Shantz

Type Material (SiO2)24. aRN+ a = 0.96 ± 0.24 (RN+ = trimethyl-1-adamantammonium)

Method R. A. Van Nordstrand, D. S. Santilli, S. I. Zones [1]

Batch Composition 5 K2O: 15 RN+ :100 SiO2 : 4400 H2O

Source Materials

deionized water
RN+ (see above) 0.72 Molar [2]
potassium hydroxide (Baker reagent, 87.8% KOH)
fumed silica (Cab-O-Sil M5, 97% SiO2, 3% H2O)

Batch Preparation (for 3.5 g product)

(1) [38.32 g water + 13.90 g (0.72M RN+) + 0.44 g potassium hydroxide], mix until dissolved
(2) [(1) + 4.00 g fumed silica], mix in the Teflon liner of a 125 mL Parr stainless steel reactor a

Crystallization

Vessel: Parr 125 mL reactor (Teflon-lined) heated in a Blue M oven
Temperature: 1500C
Time: 7 days b,c
Agitation: none

Product Recovery

(1) Upon cooling to room temperature, the product should be settled to the bottom of the reactor liner; pH with a calibrated probe should be 11.50-11.70
(2) Filter to recover solids (medium grade glass-frit funnel)
(3) Wash product with approximately 100 mL 0.01N KOH solution d
(4) Wash with approximately 1 liter water
(5) Air dry overnight while pulling a vacuum through the frit
(6) Yield: 3.52 g; 79% yield based on SiO2

Product Characterization

XRD: AFI only crystalline phase

Elemental Analysis

RN+ is approximately 10 wt% and alkali cation is usually less than 0.5 wt%. The remaining material is SiO2 [3]
Crystal Size and Habit: Typically hexagonal rods composed of identical hexagonal plates on top of each other. The rods are usually about 10 um long
Click here to view XRD pattern

References

[1] R. A. Van Nordstrand, D. S. Santilli, S. I. Zones in Molecular Sieve Science, ACS Symp. Ser. 368. W. H. Flank, T. E Whyte, (eds.), Am. Chem. Soc., Washington, D. C., 1988, pp. 236-245

[2] S. I. Zones, US Patent 4665 110 (1987)

[3] I. Petrovic, A. Navrotsky, M. E.. Davis, S. I. Zones, Chem. Mater. 5 (1993) 1805

[4] R. A. Van Nordstrand, D. S. Santilli, S. I. Zones, in Synthesis of Microporous Materials, Vol. 1, M. L Occelli, H. E. Robson (eds.), Van Nostrand Reinhold, New York, 1992. pp. 373-383

Notes

a. High speed stirring of this preparation leads to SSZ-23 formation [1].

b. The reaction can be accelerated by seeding after some initial material has been made.

c. The synthesis of the borosilicate [4] requires only one day; the crystals are smaller.

d. The alkaline wash helps to prevent unreacted silica from coming out of solution during washing and causing pore-plugging.