Prepared hydrophobic Ultra Stable Y zeolite for adsorbing toluene in humid environment

Decontamination of air or other gas streams loaded with low-concentration volatile organic compounds (VOCs) and high humidity is a prevalent task for adsorption using zeolites. Hydrophobic adsorbents were prepared with NaY zeolites as raw materials by the high-temperature hydrothermal treatment, and the degree of ion-exchange was considered as a key factor. Adsorbents were characterized by XRD, FTIR spectra, N2 adsorption-desorption isotherm, SEM, water contact angle, TG/DTG, and the adsorption capacities of water and toluene were evaluated by static adsorption test and dynamic adsorption breakthrough study. The results showed that high degree of ion-exchange was beneficial to dealumination from zeolite skeleton and crystal of zeolite remains intact in the high-temperature hydrothermal treatment. The framework silicon-aluminum ratio (SiO2/Al2O3) of modified zeolite obtained by high-temperature hydrothermal treatment reached 12.41 while the degree of ion-exchange was three (SY-3). Moreover, the hydrophobic index (HI) of SY-3 increased from 0.047 of initial Ultra Stable Zeolite to 10.059. In addition, regeneration of SY-3 was easier than that of initial NaY zeolite. Our work also has further studied the mass transfer in the zeolite and mechanism of high-temperature hydrothermal treatment under the effect of different ion-exchange degree.

High Silica Zeolite Graphical abstract

After high-temperature hydrothermal treatment, hydrophobic Y zeolite with high silicon-aluminum ratio was obtained, which showed a strong hydrophobicity while adsorbing toluene in humid environment.

USY Zeolite Conclusions

In this work, we use high-temperature hydrothermal treatment to dealuminate for Y zeolite, which does not generate a large amount of wastewater and is convenient and low-cost in industrial applications. The degree of ion-exchange had an obvious effect on the high-temperature hydrothermal treatment for NaY zeolite; the higher the ion-exchange degree was, the higher the SiO2/Al2O3 ratio after high-temperature hydrothermal treatment would be. However, the increase of the SiO2/Al2O3 ratio was at