Highly efficient synthesis of ZSM-5 zeolite by one-step microwave using desilication solution of coal gasification coarse slag and its application to VOCs adsorption

Abstract

The increased production of coal gasification coarse slag (CGCS) has placed a significant environmental load on the environment. In this research, one-step microwave synthesis employing coal gasification coarse slag desilication solution as the major source of Si and Na increased the nucleation and crystallization rate of ZSM-5 zeolite. The optimum synthesis conditions were 180 °C, 4 h, Na2O/SiO2 molar ratio of 0.2, and SiO2/Al2O3 molar ratio of 200, which led to a relative crystallinity of ZSM-5 zeolite higher than 100 % and a specific surface area of 344.27 m2•g−1. The resulting high-purity ZSM-5 zeolite not only has high SiO2/Al2O3 molar ratio, good specific surface area, and regular hexagonal prism structure, but also has high crystallinity, smooth crystal surface and great grain homogeneity because of the microwave process. Its static adsorption capacities toward p-xylene and butyl acetate were 106.84 and 115.47 mg•g−1, respectively, and the dynamic adsorption capacities were 81.44 and 176.14 mg•g−1, respectively. The preparation method of ZSM-5 zeolite with high efficiency and low cost proposed in this paper not only contributes to the high-value utilization of CGCS, but also provides an effective method and practical guidance for the removal of volatile organic compounds (VOCs).