Crystal size control of transition metal ion-incorporated aluminophosphate molecular sieves: Effect of ramping rate in the syntheses

Several aluminophosphate (AlPO) molecular sieves (AEL and AFI structures) containing Co, V or Fe are synthesized in various ramping rates (reciprocal of the time needed to reach the reaction temperature from room temperature) in order to understand the effect of the rates on the crystal size of the molecular sieves. As the ramping rate increases, the crystal size decreases probably because the nucleation rate is higher than the crystal growth rate when the reaction temperature increases rapidly. The small crystals obtained by rapid heating adsorb benzene rapidly, offering potential application in catalysis and separation. The suggested method to control a crystal size is very simple (does not require additive materials, different precursors or pH modifier, etc.), reproducible and applicable in the synthesis of various porous materials.