Thermal desorption kinetics and framework evolution in VOC-loaded FAU-Type zeolite Y: An in situ XRPD study

This study reports a detailed investigation of the desorption kinetics of toluene and chlorobenzene from a high-silica FAU-type Y zeolite (SiO2/Al2O3 ≈ 200) by in situ synchrotron X-ray powder diffraction under dynamic (298–973 K) and isothermal (443–523 K) conditions. Dynamic XRPD data reveal a progressive unit cell contraction (∼0.4–0.5 %) and an increase in the intensity of the (111) reflection, consistent with the gradual release of VOCs and pore evacuation. Activation energies were calculated using Avrami–Erofeev and Arcenegui–Troya kinetic models, the latter incorporating non-Arrhenius behavior attributed to cooperative effects. The higher activation energy observed for chlorobenzene (28.13 ± 3.93 kJ/mol) compared to toluene (17.31 ± 0.66 kJ/mol) is attributed to stronger quadrupole–cation interactions, reduced rotational entropy, and cooperative desorption barriers arising from molecular crowding. These findings provide fundamental structural insights into host–guest interactions and framework stability during VOC desorption, informing the design of regenerable zeolite adsorbents for environmental applications.