H-2 NMR-STUDIES OF BINARY ADSORPTION IN SILICALITE

This paper reports the first H-2 NMR Studies of the binary adsorption of benzene-p-xylene and benzene-cyclohexane in the zeolite silicalite. The results demonstrate that the cc-adsorption of a second component significantly influences the adsorption characteristics associated wit h pure benzene adsorbed within the same silicalite structure. Studies of equimolar, binary mixtures of benzene and p-xylene in silicalite in dicate that benzene and p-xylene access the sites most favoured during the respective single-component adsorption process, with the two spec ies forming chains of sorbed species along the straight channels of th e zeolite structure. In contrast, mixtures of benzene and cyclohexane demonstrate the phenomenon of competitive adsorption. The larger cyclo hexane molecules preferentially enter the straight channels within the silicalite framework, thereby forcing the benzene molecules, which wo uld normally access the same adsorption sites, to take up positions in sites within the sinusoidal channels and channel intersections.