Synthesis of ZSM-5 zeolite with low nitrogen content - by adding ZSM-5 seed crystals and opt. alcohol and/or ammonium hydroxide to the reaction mixt.

摘要

In the synthesis of ZSM-5 zeolite from a reaction mixt. comprising water, a silicate source, alumina and alkali metal, the organic nitrogen content of the prod. is reduced to =0.2 wt.% by adding to the reaction mixt. (a) ZSM-5 seeds, (b) mixts. of ZSM-5 seeds with alcohol, (c) mixts. of ZSM-5 seeds with alcohol and ammonium hydroxide or (d) mixts. of ZSM-5 seeds with ammonium hydroxide. The alcohol is pref. a 2-5C alkanol, esp. ethanol. The zeolite prod. contg. only small amts. of organic N-contg. cations is readily cation exchanged, to replace the alkali metal cation (usually Na) with H or NH4 or other metal, without the need for prior calcination. Thus the zeolite as produced can simply be contacted with a salt soln. of the desired cation, washed, dried and heated and is ready for use (e.g. as catalyst for (hydro)cracking, M-forming or dewaxing).