Crystallization kinetics of SAPO-37

The crystallization kinetics of SAPO-37 have been studied for a wide range of silicon contents of the gel both in static and agitated systems. The products have been characterized by XRD, chemical and thermal analysis, scanning electron microscopy, and MAS n.m.r. A liquid-phase transportation mechanism operates during crystallization. An upper limit value of ≈ 38 Si atoms per unit cell has been found. Agitation does not modify the crystallization pattern or the chemical composition of the products, but slightly favors the substitution mechanism 3. Agitation also decreases appreciably the crystallization time.