SORPTION PROPERTIES OF MO(CO)(6) ON THIN Y-ZEOLITE LAYERS

The loading of activated thin NaY zeolite layers on ZnSe with gaseous Mo(CO)(6) at room temperature under static vacuum is reported. The enc apsulation process was investigated by in situ transmission FTIR spect roscopy. The loading of zeolite Y with the metal carbonyl takes place within 80 min under mild conditions. The uptake curve indicates a comp lex sorption kinetics which differs from the conventional Fickian law of diffusion. At low coverages, Mo(CO)(6) initially diffuses very slow ly into the zeolite (D approximate to 10(-16) cm(2) s(-1)). After this induction period, it enters with a much higher velocity (D approximat e to 10(-13) cm(2) s(-1)), leading to a coverage as high as 1.80 molec ules per supercage. The kinetics of the encapsulation is described by two different sorption steps, based on the gas translation and the sol id vibration model. (C) 1998 Elsevier Science B.V. All rights reserved .