Investigations on the crystallization of larger NaA and NaX zeolite crystals in the presence of triethanolamine (I). The influence of Na2O and SiO2 content

Sodium silicate-aluminate aqueous systems with various contents of Na₂O and SiO₂ containing triethanolamine were crystallized. Optimum Na₂O and SiO₂ contents have been observed to give NaA and NaX zeolite crystals with dimensions up to 80 μm. For NaA crystals the values are: ∼ 3.5 mass% Na₂O, ∼ 1.65 mass% SiO₂; for NaX crystals ∼ 2.5 mass% Na₂O, ∼ 1.5 mass% SiO₂. – The effect of other additives on crystal size is proved. – The results are discussed in terms of nucleation and growth, reaction rate, and supersaturation. Supposition are made to gain larger crystals by maintaining the excess of solute over a longer period of time.