Simple and Rapid Synthesis of Zeolite W from K‐feldspar Via the Improved Hydrothermal Method

An improved hydrothermal method was proposed to rapidly synthesize zeolite W from alkali fusion-activated K-feldspar. The effects of m (KOH)/m (K-feldspar), n (SiO2)/n (Al2O3), n (H2O)/n (SiO2), crystallization time, and crystallization temperature on the synthesis of the zeolite W were investigated. The optimal synthesis conditions were m (KOH)/m (K-feldspar) ratio of 1.5:1, the activation time of 2 h, and the activation temperature of 500 degrees C, n (H2O)/n (SiO2) ratios of 42, n (K2O)/n (SiO2) of 0.90, n (SiO2)/n (Al2O3) of 5, crystallization time of 6 h, and crystallization temperature of 150 degrees C. The mechanism for rapid synthesis of zeolite W was illustrated. In this process, Na2SiO3 center dot 9H2O and Al2(SO4)3 center dot 18H2O were first dissolved rapidly in the synthesis system to form an amorphous gel, which contributes to the accelerated crystallization process. Compared with the state-of-the-art synthesis method, this method remarkably decreases the water content to be added in the synthesis process and crystallization time, avoids the pre-preparation process of the xerogel, and enhances the utilization rate of K-feldspar. This work provides an industrial-friendly synthesis process of zeolite W and could realize the highly efficient utilization of K-feldspar.