Studies of the synthesis of SSZ-25 zeolite in a "mixed-template" system

The synthesis of aluminosilicate zeolite, SSZ-25, is described using a two- component organic guest molecule strategy. This method has been recently de scribed by us and is quite effective in crystallizing a variety of aluminos ilicate zeolites with reduction in template cost. In this instance the orig inal organic guest component used in the discovery of SSZ-15, N ' ,N ' ,N ' -trimethyl-2- adamantammonium cation, is used in conjunction with a variet y of smaller amines. The amine is the major organic component in the synthe sis and the quaternary ammonium compound, while a minor component, is essen tial for structure direction to the desired zeolite product. Studies here s how that the adamantyl component is preferentially taken up during crystal growth. Our studies showed that the use of the multi-organic component appr oach to synthesis resulted in a faster and cheaper route to crystallizing S SZ-25. The SSZ-25 has been described in the literature as having the MWW to pology and as such has two different channel systems accessed by 10-ring op enings: the channel systems do not intersect. One set of 10-rings open into large cavities. In this study we used NMR spectroscopy to examine the as-m ade materials and to see if the two organic components are used in differen t capacities in the synthesis, probing if the admantyl component is only fo und in these larger cavities. The crystalline products could be affected by solvent extraction with polar solvents like dimethylformamide: the X-ray p owder patterns and elemental analyses changed with solvent treatment. The s olvent-treated crystals were studied by NMR spectroscopy, elemental analysi s, and argon adsorption. The two-component organic guest approach was also found to be quite flexible not only with regard to the amine, but also towa rds the quaternary ammonium compounds. Non-adamantyl polycyclic templates c ould be used, and polar but non-quaternized adamantyl derivatives also succ eeded in directing towards SSZ-25 formation. On the other hand, in one inst ance it was shown that the two-component approach favors SSZ-25 as the kine tic product but at longer run times Ostwald ripening was observed, leading to the disappearance of SSZ-25 and formation of ferrierite zeolite and quar tz.