Characterization of the hydroxyls in offretite zeolite

Abstract

It is shown that three structural hydroxyl groups are generated in offretite upon cation exchange. The 3660 cm^–1 OH groups are either not acidic or only slightly so and are probably located in the inaccessible hexagonal prism (O₆H). The 3610 and 3550 cm^–1 hydroxyls are acidic. Their strength increases at low cation content. The 3610 cm^–1 groups are mainly located in the channel (O₅H) while the low frequency groups are suggested to be in the cancrinite cage (O₂H or O₄H).