Infrared spectroscopic study of acrylonitrile adsorbed on mordenite zeolites. Part 1.—Surface interaction of CN triple bond

Abstract

Adsorption of acrylonitrile (ACN) on cation-exchanged mordenites, NaM, BaM, ZnM and CdM (M = mordenite), was studied by means of infrared spectroscopy.

Upon adsorption of ACN, the CN stretching vibration was shifted to higher frequency regions with respect to the liquid-phase vibration. This is ascribed to interaction with surface cation species, which may occur in more than one bonding mode as exemplified below: [graphic omitted] where Σ refers to surface active sites such as exchange cations of n valence state, to protonic or aprotonic sites.

Evidence shows that the interaction between ACN and the exchanged cation species occurs through donation of the nitrogen lone-pair electrons and through the polarization of the CC double bond. In the present paper the former interaction as the principal mechanism will be discussed and the latter will be communicated in Part 2.