Rapid synthesis of thin SAPO-34 membranes using microwave heating

SAPO-34 membranes were prepared by microwave (MW) heating method using a colloidal solution containing tetraethylammonium hydroxide as a template. SAPO-34 in the form of seed and membranes were investigated for their properties such as morphology, pore characteristic, crystallinity and thickness, using characterization method of scanning electron microscope (SEM), X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), FT-IR and nitrogen adsorption-desorption. SAPO-34 membrane was also prepared using conventional hydrothermal heating and studied for its comparison with those formed by MW heating. SAPO-34 membrane containing homogenous SAPO-34 crystals with average size of ~0.7 μm was formed during MW heating. Compare to the conventional hydrothermal heating, MW heating facilitates formation of SAPO-34 crystals with narrower size distribution due to the highly uniform volumetric heating provided by microwave heating. MW heating was able to produce thinner SAPO-34 membrane (1–2 μm) where as hydrothermal heating formed thicker SAPO-34 membrane (~3.6–5.5 μm). The synthesis time for membrane formation was significantly shortened from 24 h for conventional hydrothermal heating to 2 h for microwave heating at 200 °C.