Dry gel conversion synthesis of SAPO-34 nanocrystals

SAPO-34 nanocrystals were synthesized by a dry gel conversion method using tetraethylammonium hydroxide as a structure-directing agent. The crystal growth of SAPO-34 was studied by X-ray diffraction and field-emission scanning electron microscopy. After 3 h, 45-nm SAPO-34 crystals with an amorphous phase were observed. The crystal size increased to 70 nm after 6 h, but did not increase greatly thereafter. The average crystal size of the final product was 75 nm. The nucleation density for SAPO-34 crystals in dry gel conversion appeared to be much higher than that under hydrothermal conditions, resulting in the formation of small crystals.