Detailed Investigation of Thermal Regeneration of High-Silica ZSM-5 Zeolite through in Situ Synchrotron X-ray Powder Diffraction and Adsorption Studies

Adsorption is important for many applications including catalysis and water remediation technology. To improve the performances of such applications, it is essential to have a deep understanding of adsorbent-adsorbate interactions, and of the dynamics involved in adsorption/desorption processes of porous adsorbent materials. In this study, the thermal desorption of high-silica (HS) ZSM-5 zeolite loaded with mixtures of organic compounds (namely, methyl tert-butyl ether/toluene, and methyl tert-butyl ether/1,2 dichloroethane) was investigated in real time using in situ high-temperature synchrotron X-ray powder diffraction (HT-XRPD). A picture of both kinetics and dynamic behavior of this adsorbent during thermal regeneration is presented, including the evolution of refined occupancies of the host molecules as a function of temperature. The adsorption enthalpy and entropy of the organic compound were also evaluated and compared with desorption temperature. It was found that configurational effects can affect the mobility of the molecules inside the framework, and in particular, the desorption temperature seems to be mainly related to the position of the molecule inside the porous structure.