Adsorption of a polar or a non-polar chloroalkene on a ZSM-5 zeolite at 298 K

The physisorption of trichloroethylene and tetrachloroethylene on ZSM-5 (Si/Al = 339) zeolite was investigated at 298 K using thermogravimetry, differential microcalorimetry and X-ray diffraction. The zeolite always undergoes a monoclinic-orthorhombic structural change during the adsorption of the first molecules. An alignment of the polar trichloroethylene molecules inside all the channels of the zeolite is proposed to account for the experimental results. A phase transition of the non-polar tetrachloroethylene is suggested to produce the stepped isotherm, the steep rise in the heat curve and the high increase in the mobility of the molecules for the loading of 4 molecules per unit cell.