demineralized water
sodium hydroxide, reagent grade (Riedel-de Haen)
pyrogenic silica (Cab-o-Sil M5 ) ^a
pyrrolidine (Pyrr), (Fluka)
aluminum sulfate (Al₂(SO₄)₃. 18H₂O, Fluka)
sulfuric acid (96 wt% H₂SO₄, Fluka)

Batch Preparation (for 14 g product) ^b

(1) [195.8 g water + 4.40 g sodium hydroxide], mix until dissolved
(2) [(1) + 16.5 g silica], add silica to solution (1) over the course of ~5 minutes under continuous stirring
(3) [24.4 g water + 8.81 g pyrrolidine + 1.79 g aluminum sulfate], mix until dissolved
(4) [(2) + (3)], add solution (3) to solution (2) with good mixing
(5) [(4) + 4.33 g sulfuric acid], add acid dropwise with stirring; final gel pH = 12.6

Vessel: stainless steel autoclave (300 mL) ^c
Temperature: 180¡C
Time: 50 hours
Agitation: autoclaves are rotated ~30/minutes

(1) Cool and filter
(2) Wash extensively with demineralized water
(3) Dry at 100¼C for 16 hours
(4) Yield: approx. 14 g

XRD: MTT (only crystalline phase), competing phases: MFI (contaminated autoclave)
cristobalite (occasional overheating, or pH too high)
Elemental Analysis: SiO₂/Al₂O₃ = 78 (AFS/ICP) ^d
Crystal Size and Habit: bundles of needles ^e
Click here to view XRD pattern

[1] S. Ernst, R Kumar, J. Weitkamp, in Zeolite Synthesis, Am. Chem. Soc. Symposium Series 398, M. Occelli, H. Robson (eds.), 1989, pp 560-573

a. Cab-O-Sil M5 must be used; other silica sources, such as silica sol or sodium silicate, lead to different products.

b. The synthesis has been successfully scaled up to a 5 liter autoclave (stirring rate:
120/minutes, yield: 250 g).

c. The crystallization vessels have to be cleaned very thoroughly in order to avoid seeding effects from residual crystallites of ZSM-5, for example.

d. With pyrrolidine as template, the molar ratio can be varied between 70 and 150.

e. Platelet-like ~1 um can be synthesized using C₇diquat [(CH₃)₃N-(CH₂)₇-N(CH₃)₃]Br₂ as template. [1]