Liquid Zeolite One of the World's Most Potent Liquid Zeolite!
The most recent stages in the quest for more siliceous molecular sieve compositions was achieved in the late 1960's and the early 1970's with the synthesis at the Mobil Research and Development Laboratories of the "high silica zeolites" . First in that row was zeolite beta (Fig. 4) discovered by R. L. Wadlinger, G. T. Kerr and E. J. Rosinski, and later ZSM-5 (Fig. 5) discovered by R. J. Argauer and G. R. Landolt. These are molecular sieve zeolites with Si/Al ratious from 10 to 100 or higher, with different surface characteristics. In contrast to the "low" and "intermediate" silica zeolites, representing heterogeneous hydrophilic surfaces within a porous crystal, the surface of the high silica zeolites is more homogeneous with an organophilic-hydrophobic selectivity . They adsorb stronger the less polar organic molecules and only weakly interact with water and other polar molecules.
Biorefineries - Essential Chemical Industry
The next commercially successful synthetic zeolite introduced in the early 1960's was a large pore mordenite (Fig. 2) with ratio Si/Al ≈ 5. The improvement in thermal, hydrothermal, and acid stability coupled with its specific structural and compositional characteristics resulted in application of mordenite as an adsorbent and hydrocarbon conversion catalyst . Type L zeolites (Fig. 3), discovered in the early 50's by D. W. Breck and N. A. Acara with a Si/Al = 3.0 have unique framework topology. They were adapted as commercial catalysts in selective hydrocarbon conversion reactions.
Cation exchange is exploited in water softening, where alkali metals such as Na+ or K+ in zeolite framework are replaced by Ca2+ and Mg2+ ions from water. Many commercial washing powders thus contain substantial amounts of zeolites that enhance washing efficiency. LTA have the largest scale production of synthetic zeolites for use as "builders" in domestic and commercial detergents to remove the calcium and magnesium "hardness" .