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).
