TOWARD THE RATIONAL DESIGN OF ZEOLITE SYNTHESIS - THE SYNTHESIS OF ZEOLITE ZSM-18

ZSM-18 has, until now, only been made using one trisquaternary ammonium ion, 2,3,4,5,6,7,8,9-octahydro-2,2,5,5,8,8-hexamethyl-1H-benzo[1,2-c:3,4-c':5,6-c'']tripyrrolium, 1. This trisquaternary is difficult to make and destabilizes the zeolite during calcination. We used modeling to aid the design and selection of new templates for ZSM-18. The geometry and charge distribution of these templates were chosen to best fit our estimate of ''templating.'' Template 2, tris-(2-trimethylamonioethyl)amine, is easy to synthesize in high yield and can be routinely calcined to produce highly sorptive ZSM-18. Template 3, tris-(2-trimethylamonioethyl)methane, produces ZSM-18 only when seeded. Si n.m.r. and Al n.m.r. indicate that aluminum is not located exclusively in the three rings as has been predicted theoretically. [H]-ZSM-18 can be steam-dealuminated. The Si n.m.r. of the dealuminated material agrees with the number of sites and relative occupancies expected.