REVIEW Some Possibilities of Catalytic and Noncatalytic Utilization of Zeolites a D. MRAVEC, b J. HUDEC, and c I. JANOTKA a Department of Organic Technology, Faculty of Chemical and Food Technology, Slovak University of Technology, SK-812 37 Bratislava e-mail: [email protected] b Department of Agrochemistry and Nutrition of Plants, Faculty of Agrobiology and Food Resources, Slovak University of Agriculture, SK-949 76 Nitra e-mail: [email protected] c Institute of Construction and Architecture, Slovak Academy of Sciences, SK-845 03 Bratislava e-mail: [email protected] Received 15 October 2003 Some possibilities of catalytic and noncatalytic utilization of zeolites are introduced. Zeolites are very important materials with very broad applications not only in refineries as catalysts, in sorption and separation processes, but also in agriculture, new building materials, and environmental engineering. Some significant directions of zeolites utilizations are presented but the importance of these interesting materials is much greater. This paper summarizes the knowledge on zeolites use in chemical and petrochemical industry, agriculture, building industry, and environmental engineering. 1. INTRODUCTION Zeolites are crystalline aluminosilicates with com- position represented by the empirical formula M x D y [Al x+2y Si n−(x+2y) O 2n ]mH 2 O where x is the number of monovalent cations, y is the number of bivalent cations, n is cation valence, and m is the number of water molecules in the zeolite for- mula. The history of zeolites was started by the discovery of the first zeolite mineral stilbit in 1756 by Cronsted. The huge progress in the knowledge of structure, syn- thesis, modification, characterization, and very broad usage of unique characteristics of zeolites and zeolite- like materials was reached in the period of about 250 years from the discovery of the first zeolitic ma- terial and especially in the period of the last 50— 60 years. The development started from aluminosil- icate zeolites to new zeolites and zeolite-like materi- als as aluminophosphates, metallosilicates, and met- allophosphates and from microporous to mesoporous molecular sieves. Today, mainly synthetic zeolites are used widely in petroleum refining and chemical pro- cess industries as selective adsorbents, catalysts, and ion exchangers. But the importance of zeolites and zeolite-like materials is greater. The present paper shows some possibilities of cat- alytic and noncatalytic utilization of zeolites. 2. BASIC CHARACTERISTICS OF ZEOLITES Three-dimensional framework of zeolites consists of AlO 4 and SiO 4 tetrahedra linked to each other by the sharing of oxygen ions. | | | | O O O O | _ | Me+ | _ | Me+ — O — Si — O — Al — O — Si — O — Al — O — | | | | O O O O | | | | Each AlO 4 tetrahedron in the framework bears a negative charge which is balanced by an extra frame- 62 Chem. Pap. 59 (1) 62—69 (2005)
Some Possibilities of Catalytic and Noncatalytic Utilization of Zeolites
May 03, 2023
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