Research Progress on Zeolite Synthesis Using Fly Ash as Raw Material

Fly ash is a large-volume industrial solid waste discharged from coal-fired power plants, with an annual national emission exceeding 600 million tons. Its stockpiling not only occupies land resources but also easily causes environmental problems such as air and water pollution. Zeolites, as a class of silicoaluminate crystalline materials with regular pore structures, high specific surface areas, and excellent adsorption/catalytic properties, are widely applied in the fields of adsorption and separation, catalytic reactions, and environmental remediation. The synthesis of zeolites using fly ash as a silicon-aluminum source achieves the dual goals of "treating waste with waste" and high-value resource utilization, thus emerging as a research hotspot in the fields of materials science and environmental engineering in recent years. This paper systematically reviews the physicochemical properties of fly ash and their impacts on zeolite synthesis, elaborates in detail the principles, process parameter optimization, product performance, and research progress of mainstream preparation methods including hydrothermal synthesis, solvothermal synthesis, and microwave-assisted synthesis. Furthermore, it summarizes the current application status of fly ash-derived zeolites in wastewater treatment, gas adsorption, catalytic reactions, and other fields, and points out the existing problems in current research such as complex pretreatment, high energy consumption, and difficulties in large-scale production. This work provides a reference for the resource utilization of fly ash and the low-cost preparation of zeolites.