PROCESS TO MAKE SMALL CRYSTALLITES OF ZSM-5

摘要

ZSM-5 crystallites having dimensions below about 0.3 micrometer are produced in the as synthesized form with very low levels of blocking tetrapropyl ammonium (Q) ions. The reaction mixture contains sources of silica, soda, alumina, a polyol such as ethylene glycol and trace amounts of Q ions as nucleation agents. Because the crystallites as synthesized from the aqueous medium exhibit only a very small fraction of blocking cations, there is always a diffusion path for the hydrated sodium ions to be exchanged without the need of prior removal of the blocking cations by calcination or otherwise. The small size crystallites can be exchanged, blended with matrix material, and formed into catalyst particles. The silica to alumina ratio can be varied and when no aluminum is added, silicalite may be formed. The synthesis can be done in 24 hours or less.