Zeolites

Literature References: Crystalline, hydrated alkali-aluminum silicates of the general formula M2/nO.Al2O3.ySiO2.wH2O where M represents a group IA or IIA element, n is the cation valence, y is 2 or greater and w is the number of water molecules contained in the channels or interconnected voids within the zeolite. The cations are mobile and capable of undergoing ion exchange. Zeolites occur naturally in sedimentary and volcanic rocks, altered basalts, ores, clay deposits. Some 40 known zeolite minerals and a great number of synthetic zeolites are available commercially. Ref: Milton, US 2882243 (1959 to Union Carbide). Environmentally friendly synthesis: H. Lee et al., Nature 425, 385 (2003). Reviews: D. W. Breck, R. A. Anderson, "Molecular Sieves" in Kirk-Othmer Encyclopedia of Chemical Technology vol. 15 (Wiley-Interscience, New York, 3rd ed., 1981) pp 638-669; P. L. Layman, Chem. Eng. News 60, 10 (Sept. 27, 1982); J. Haggin, ibid. 60, 9 (Dec. 13, 1982). Books: Adv. Chem. Ser. 101, 102, entitled "Molecular Sieve Zeolites - I, II," E. M. Flanigan, Ed. (ACS, Washington DC, 1971) 526 pp, 459 pp; Adv. Chem. Ser. 121, entitled "Molecular Sieves," W. M. Meier, Ed. (ACS, Washington DC, 1973) 634 pp; D. W. Breck, Zeolite Molecular Sieves (John Wiley, New York, 1974) 771 pp; Natural Zeolites: Occurrence, Properties, Use, L. B. Sand, F. A. Mumpton, Eds. (Pergamon, Oxford, 1978). Studies on fibrous zeolites as possible environmental hazards: A. N. Rohl et al., Science 216, 518 (1982); Y. I. Baris, Arch. Environ. Health 37, 177 (1982). Use as microscopic chemical reactor vessels: R. Pool, Science 263, 1698 (1994).