| abstract |
As synthesized by conventional technique, zeolite ZSM-5 is crystallized in the presence of substantial amount of tetraalkylammonium cations, the alkyl groups of which contain 2 to 5 carbon atoms, such as, for example, tetrapropylammonium. When synthesized in the conventional way, ZSM-5 contains tetraalkylammonium cations as well as substantial amount of sodium ions. To obtain a more catalytically active form of ZSM-5, the sodium ions must be exchanged to very low levels. By synthesizing zeolite ZSM-5 according to the present method, i.e. in the presence of one or more diamines and with a specifically defined reaction mixture composition, ZSM-5 having different organic nitrogen-containing cations but the same crystal structure as conventionally prepared ZSM-5 is obtained. The ZSM-5 prepared in accordance hereto is very low in sodium content as synthesized. |