|
EAB |
TMA-E |
Si(74), Al(26) |
Contributed by Rosario Alello and Flaviano Testa
Verified by B. Schoeman and by B. Subotic
Type Material [Na6.84(TMA)3.05] [(AlO2)9.25(SiO2)26.75]. 17.12 H2O a (TMA = tetraxnethylainmonium)
Method R. Aiello, R. M. Barrer [1]
Batch Composition 5 (TMA)20 : 3 Na2O : Al2O3 :15 SiO2: 500 H2O
Source Materials
distilled water
tetramethylammonium hydroxide (Fluka, purum, 25% aqueous solution)
sodium hydroxide (Carlo Erba, pellets, reagent grade, 30% aqueous solution)
alumina (Pfaltz and Bauer, Al(OH)3, 65% Al2O3)
silica (Sigma, fumed, 99+% SiO2)
Batch Preparation (for 1.4 g dry product)
(1) [13.78 g water + 9.10 g tetramethylammonium hydroxide solution + 2.00 g sodium hydroxide solution], mix until dissolved
(2) [(1) + 0.39 g alumina], mix until homogeneous
(3) [(2) + 2.25 g silica], mix thoroughly
Crystallization
Vessel Teflon container
Time: 14 days
Temperature: 80 ± 2¡C
Agitation: container is rotated
Product Recovery
(1) Filter and wash thoroughly
(2) Dry at ambient temperature
(3) Yield: near 100% on Al2O3
Product Characterization
XRD: EAB (only phase observed); competing phase: FAU (trace sometimes present) b
Elemental Analyses: (Na2O)0.74 : ((TMA)2O)0.33 : Al2O3 : 5.74 SiO2 c
Crystal Size and habit: 1-2 um faceted spherulites d,e
Click here to view XRD pattern
Reference
[1] R. Aiello, R. M. Barrer, J. Chem. Soc. A (1970) 1470
Notes
a. Excess cations attributed to SiO- fragments in the framework.
b. FAU traces were observed from systems with lower TMA/Na ratio and with lower H2O content.
c. As reported in Ref. [1] for samples obtained both from batches with Na+/ (TMA)+ = 0.5/0.5 and 0.2/0.8.
d. TMA+ could not be removed by NaNO3 exchange.
e. By thermal analysis, water is first lost endothermally, followed by exothermal oxidative decomposition of TMA+.