1. (a) The term porotectosilicates has been proposed by Barrer to encompass that class of siliceous crystalline materials which includes both zeolites and solids that resemble zeolites in crystal structure but which may not be capable of ion exchange. Tectosilicates are characterized by the fact that the SiO4 tetrahedra are linked at all corners to form three-dimensional arrays. The recent discovery of new families of crystalline microporous borophosphates [1b], BPO4, and aluminophosphates [1c], AlPO4, which possess structures reminiscent of, if not identical to, those of many zeolites but which are partly- or non-siliceous, suggests that a new term is needed to encompass these materials. We suggest ?porotectophosphates?, which could encompass elements other than Al in the structure, as such a generic name;
2. (b) et al., Faraday Society Discussion, Nottingham, September 1981, p. 346;
3. Aluminophosphate molecular sieves: a new class of microporous crystalline inorganic solids
4. : The Sorption of Gases and Vapours by Solids, Routledge, London 1932, Chapter 5.