Adsorption of m-xylene on prehydrated zeolite BaX: Correlation between temperature-programmed desorption and low-temperature neutron powder diffraction studies

摘要

Adsorption of m-xylene on partially hydrated zeolite BaX is studied by thermogravimetry, mass spectrometry, temperature-programmed desorption and neutron diffraction for different m-xylene loadings of the zeolite. Macroscopic and microscopic measurements, for both molecules, were correlated and relationships were found between the crystallographic positions of the adsorbed molecules on the zeolite and macroscopic properties such as the number and the area of the peaks in the desorption spectra for m-xylene or water. The influence of water molecules on the adsorption phenomenon of m-xylene on BaX zeolite was characterized. In particular, it was shown that the increase of the filling of the prehydrated zeolite with m-xylene leads to a rearrangement of the adsorbed aromatic molecule on its adsorption site. This displacement produces a weakening of the m-xylene-adsorbent interactions. It was also shown that the filling of the zeolite BaX with m-xylene modifies the distribution (and the energy of activation for desorption phenomenon) for water molecules, but not the location of the water adsorption site. [References: 34]