Structure directing agents SDAs

Fig. 4 Proposed defect cluster model in as-made zeolites with quaternary ammonium cations as structure directing agents (SDAs) hydrogen bond distances of 1.68 A are determined experimentally from the H NMR chemical shift of 10.2 ppm X and Y are atoms not further specified in the SDA the interaction between the SDA and the SiO- group is assumed based on bond valence arguments (see text)...

Fig. 5 (a) Structure directing agent (SDA) in the synthesis of zeolite ITQ-3 N quaternary nitrogen A-I carbon atoms of SDA, l,3,3,6,6-pentamethyl-6-azonium-bicyclo[3.2.1]octane some 13C line assignments were not unequivocally possible, so these are left open the orientation of the dipole moment was calculated with a semiempirical AM-1 simulation with the origin at the center of gravity of the molecular cation (b) 13C H 27A1 REAPDOR experiment on synthetic zeolite ITQ-3. Adapted from [204]... 

The advent of the addition of a quaternary ammonium cation as template or structure directing agent (SDA) to the alkaline gel by Barter and coworkers, and Mobil Oil coworkers, led to the Si02 enriched zeolite A in the case of Barter and to the high silica zeolites. Beta and ZSM-5, by the Mobil group. The latter synthesis temperature typically is 100-200 °C, higher than Milton s original work. 

Zeolites have micropores with ordered size and solid acidity, and there has been growing interest in the application of zeolites as catalysts as well as molecular sieves. We investigated the synthesis of novel zeolites by using ammonium salts as structure-directing agents (SDAs) [1, 2]. 

In some cases, the organic can be extracted from the molecular sieve. For pure-silica BEA, Jones et al. [36] were able to extract the tetraethylammonium fluoride that was used as the structure directing agent (SDA). In that case, a small organic was used to prepare a 12 MR material. In some aspects, this situation is... 

REAPDOR, and H- A1 REAPDOR solid state NMR. The distribution of acid sites is not random, and a local charge-ordering around monoquatemary structure directing agents (SDAs) is discerned. No such charge ordering was observed for diquatemary SDAs. These methods provide a versatile tool to locate acid sites around the SDA. 

P-30 - Synthesis of zeolite SSZ-35 using N-methyl hexahydrojulolidinium salt as a new family of structure-directing agents (SDAs)... 

Three isomers of N-methyl hexahydrojuladinium salts were successful in preparing molecular sieves for the first time. When they were used as structure-directing agents (SDAs), they gave rise to the synthesis of three molecular sieves, SSZ-35, SSZ-31 and RUB-13. The stereoconfigurations of these organics are supposed to be an extremely important factor. 

Various parameters are known to influence the kinetically controlled synthesis of silica-rich zeolites and related compounds such as porosils. In syntheses where diethylenetriamine is acting as a structure-directing agent (SDA), different porosil structures can crystallize nonasil, ZSM-48, silicalite-1 and an unknown structure. The type of porosil obtained is found to depend upon the concentration of the SDA, i.e. upon the compositional ratio between diethylenetriamine and water in the synthesis gel. The results can be rationalized on the basis of the structural arrangements of the diethylenetriamine molecules in the porosil formed. These arrangements are influenced by the competition between intramolecular hydrogen bonds within individual diethylenetriamine molecules, by the ability to form intermolecular hydrogen bonds between the molecules of the SDA and by the solvation of these molecules by water. 

The role of EY as a structure-directing agent (SDA) in the electrodeposition of ZnO could be developed to an even greater extent (Figure 4.2b) when the deposi-... 

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