硅铝协同利用制备高钙粉煤灰基ZSM-5分子筛

利用粉煤灰（CFA）生产分子筛是实现其高附加值利用的有效途径。以高钙粉煤灰为原料，结合高温焙烧、酸浸纯化和碱熔活化等预处理技术，采用变温水热晶化法制备了纯净的ZSM-5分子筛。采用XRD、XRF、FTIR、SEM、NH3-TPD、OH-FTIR及N2吸附-脱附等手段对样品的组成、结构、形貌和酸性质进行了表征。结果表明，酸浸纯化可以去除96%以上的氧化钙，碱熔活化将惰性的莫来石晶相转变为可溶性硅铝酸盐。低温-高温两步水热晶化法制备的ZSM-5分子筛结晶度高、粒径小（800 nm×300 nm×100 nm）且分散度好，具有较高的比表面积（319.22 m2/g）、外表面积（48.28 m2/g）和丰富的微孔结构（0.16 cm3/g）。与化学试剂为原料一步水热法合成的HZSM-5相比，高钙粉煤灰基HZSM-5酸强度略有下降，总酸量和Bronsted酸量降低，弱酸占比增加，在吸附和催化等领域具有很好的应用潜力。

Preparation of High-Calcium Coal-Fly-Ash-based ZSM-5 Zeolite by Synergistic Utilization of Silica and Aluminum

The production of molecular sieves from coal fly ash (CFA) is an effective way to achieve its high value-added utilization. By using high calcium CFA as raw material, pure ZSM-5 molecular sieves were prepared by a variable-temperature hydrothermal crystallization method combining pretreatment techniques such as high temperature roasting, acid leaching purification and alkali fusion activation. The composition, structure, morphology and acid properties of the samples were characterized by XRD, XRF, FTIR, SEM, NH3-TPD, OH-FTIR and N2 adsorption-desorption. The results show that acid leaching purification can remove more than 96% of calcium oxide, and alkali fusion activation transforms the inert mullite crystalline phase into soluble silica-aluminates. The ZSM-5 molecular sieve prepared by two-step hydrothermal crystallization method has high crystallinity, small particle size (800 nm×300 nm×100 nm) and good dispersion, with high specific surface area (319.22 m2/g), high external surface area (48.28 m2/g) and abundant microporous structure (0.16 cm3/g). Compared with HZSM-5 synthesized by one-step hydrothermal method based on chemical reagents, the high-calcium CFA-based HZSM-5 has slightly lower acid strength, lower total and Bronsted acid amounts, and rises percentage of weak acids, which has good potential for applications in fields such as adsorption and catalysis.