CONDENSATION OF OLEFINS ON CLAYS, GAS-SOLID SYSTEMS .1. GRAVIMETRIC METHODS

The adsorption-condensation of olefins was studied on 7 adsorbents: 2 commercial clays, a natural clay and its protonated form, gamma-alumin a and porous and nonporous silicas. These adsorbents were characterize d by X-ray diffraction (XRD), chemical analysis, thermogravimetric ana lysis (TGA), differential thermal analysis (DTA) and determination of specific surface area measurement by the BET method. The experiments w ere carried out gravimetrically, in gas- or vapor-solid systems, at 25 degrees C, and on adsorbents dried at 120 degrees C. Adsorption-conde nsation of olefins are fast processes, diffusion controlled, Alumina a nd silicas adsorb olefins and paraffins only reversibly, but are unabl e to condense olefins. The water polarized by the countercations is th e source of Bronsted acid sites. When the gas phase is evacuated or sw ept with inert gas, the condensation terminates. On clays, paraffins a re reversibly adsorbed but no condensation was observed.