Contributed by Mario Occelli

deionized water
sodium hydroxide, reagent grade (usually ~-.97% NaOH)
gallium oxide (99.99%)
silica sol (Dupont HS-40, 39% SiO₂, 0.5% Na₂O)

(1) [32.0 g water + 32.0 g sodium hydroxide + 18.7 g gallium oxide], dissolve gallium oxide in 50% NaOH at 80⁰C with stirring until a clear solution is obtained. Cool to ambient temperature
(2) [(1) + 70.6 g water], mix ^a
(3) [150.2 g silica sol + 70 g water], mix
(4) [(3) + (2)], add the sodium gallate solution dropwise to the vigorously-stirred, diluted silica sol. Continue stirring for 16 hours at ambient temperature

Vessel: one-liter round-bottomed flask with reflux condenser
Incubation: 16 h at 25⁰C with stirring
Temperature: 95⁰C ^b
Time: 90 hours ^c

(1) Filter and wash with deionized water until pH < 10
(2) Dry at 110⁰C
(3) Yield: near 100% on Ga₂O₃

XRD: FAU; no other crystalline phases or amorphous material observed
Elemental Analyses: 38.7 wt% Ga₂O₃, 38.0 wt% SiO₂, 12.5 wt% Na₂O (0.98 Na₂OGa₂O₃ : 3.06 SiO₂) ^d
Click here to view XRD pattern

[1] M. L Occelli, US Patent 4 803 060 (1989)
[2] M. L Occelli, A. E. Schweizer, H. Eckert, A. Auroux, P. S. Iyer, AppI. Catalysis (to be submitted)

a. Diluted sodium gallate solution must be clear.

b. The temperature of the stirred, cold-aged hydrogel is ralsed to 95⁰C. When the hydrogel reaches 95⁰C the stirring is immediately stopped.

c. Method to reduce crystallization time given in ref. [1, 2]

d. After calcination at 600⁰C for 2 h; BET surface area 541 m²/g