Shaped binderless high SiO₂/Al₂O₃ ratio Beta/ZSM-5 composites for volatile organic compounds adsorption

Volatile organic compounds (VOCs) are primary components of air pollutants that pose a risk to the environment and public health. Adsorption is regarded as one of the most effective and practical strategies for dealing with VOCs contamination. A series of shaped binderless Beta/ZSM-5 composites were produced by a vapor-phase transfer method and dealuminated using a sulfuric acid solution to increase SiO₂/Al₂O₃ ratio after steaming treatment to further increase the hydrophobicity of the samples. The shaped binderless Beta/ZSM-5 composites were characterized with XRD, SEM, TEM, XRF, NMR and N₂ adsorption-desorption. The VOCs adsorption properties of the dealuminated Beta/ZSM-5 mesoporous composites and microporous ZSM-5 zeolites were assessed using dynamic adsorption experiments and temperature-programmed desorption (TPD) under both dry and wet environments. The results revealed that the dealuminated Beta/ZSM-5 composites have larger specific surface area and mesopore volume as well as strong hydrophobicity, and exhibit higher toluene, butyl acetate and o-xylene adsorption capacity than ZSM-5 under either dry or wet environments.