Molecular sieve zeolite technology - the first twenty-five years

Abstract

In twenty-five years molecular sieve zeolites have substantially impacted adsorption and catalytic process technology throughout the chemical process industries; provided timely solutions to energy and environmental problems; and grown to over a hundred million dollar industry worldwide. The evolution in zeolite materials with improved or novel properties has strongly influenced the expansion of their applications, and provided new flexibility in the design of products and processes.

Ethylene recovery from low grade gas stream by adsorption on zeolites and controlled desorption

“…The most surprising phenomenon was the increasing ethylene concentration with decreasing nitrogen GHSV (Table 3 and Figure 3), whereas the concentration of carbon dioxide remained almost constant. A tentative explanation of the present data involves consideration of the air separation process by "pressure swing adsorption" on 5A and 13X zeolites (Keller and Jones, 1980;Flanigen, 1984). This industrial process exploits the large difference in quadrupole properties (and rather than the sieving action of the adsorbents) between the molecules of oxygen [0.10 x nm3 (Breck, 1974, p. 650)] and nitrogen [0.31 X nm3].…”

“…This industrial process exploits the large difference in quadrupole properties (and rather than the sieving action of the adsorbents) between the molecules of oxygen [0.10 x nm3 (Breck, 1974, p. 650)] and nitrogen [0.31 X nm3]. The nitrogen molecule is firmly adsorbed on the zeolite by a strong specific interaction of the nitrogen molecular quadrupole with the cation (Flanigen, 1984, and reference therein) and, therefore, enriched oxygen (Kenney and Kirby, 1985) can be obtained. Carbon dioxide and ethylene are both quadrupole molecules [0.64 x m3 and 0.48 x nm-3, respectively (Breck, 1974, p. 650)].…”

“…In order to achieve recovery of ethylene under the best conditions, carbon dioxide had to be at least partially removed. Thus, some runs were performed with the 4A zeolite which was known to be very efficient for carbon dioxide removal from bulk ethylene and other hydrocarbons (Flanigen, 1984;Ruthven, 1983). Other runs were done with the 3A zeolite (on the basis of considerations described in the "Discussions" section).…”

From Zeolite to Host-Guest Nanocomposite Materials

“…Adsorbents The major use of zeolites as ion-exchange agents is for water softening applications in the detergent industry and substitute use of phosphates. Natural zeolites find considerable use for removal of Cs + and Sr 2+ radioisotopes by ion exchange from radioactive waste streams [129]. Synthetic zeolites are extensively used as catalysts in the petrochemical industry.…”

Application of Synthetic Nanozeolite Sodalite in Drug Delivery

“…They are based on a three-dimensional framework of SiO4 and AlO4 tetrahedral that results in an extended uniform network of channels and pores (Rimoli et al, 2008). Zeolites have been extensively used in various industrial applications based on their properties to act as catalysts, ion exchangers, adsorbents, and detergent builders (Pavelic, 1980;Sersale, 1985;Naber et al, 1994;Garces, 1999;Colella, 1999). By virtue of these unique properties, they can absorb large amounts of molecules both in the gas and in liquid phases, facilitate ion exchange, and act as molecular sieves (Kralj et al, 2003).…”