Rapid and high efficient synthesis of zeolite W by gel-like-solid phase method

Abstract

Abstract Zeolite W was synthesized rapidly and efficiently by gel-like-solid phase method using silica-alumina xerogel as the silica-alumina source and potassium hydroxide as the alkali source. The as-synthesized samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersion spectroscopy (EDS), Fourier transform infrared spectroscopy (FT-IR) and N2 adsorption-desorption. The results exhibited that zeolite W can be synthesized with silica-alumina gel (n(Al2O3)/n(SiO2) = 0.2) under a wide range of synthesis conditions: n(K2O)/n(SiO2) = 0.125–0.5, n(H2O)/n(SiO2) = 5.55–14.81, crystallization temperature T = 125–150 °C, and crystallization time t = 6–18 h. Among them, a batch of uniform and well crystallized zeolite W was synthesized under 150 °C for 12 h with the mole ratio of n(K2O)/n(SiO2) = 0.375 and n(H2O)/n(SiO2) = 7.40. The specific surface area of optimal sample is 221.98 m2 g−1, and NH4+ exchange capacity in exchange fluid is up to 38.12 mg g−1 and the highest recovery amount of K+ is 51.21 mg g−1 in artificially simulated seawater. The mechanism of zeolite W synthesized by gel-like-solid phase method is liquid-solid two phases transformation mechanism. Compared with the conventional hydrothermal synthesis system, the gel-like-solid phase synthesis method greatly reduced the amount of water, shortened the crystallization time, improved the utilization rate of raw materials and simplified the recovery process of mother liquor.