Structure of K-Substituted Zeolite Clinoptillolite and Its Behavior Upon Compression in Penetrating and Non-Penetrating Media

Abstract

K-substituted zeolite - clinoptillolite

K_6.16Na_0.16Ca_0.07Mg_0.03(H₂O)_19.2|[Al_6.45Si_29.55O₇₂] (space group C2/m, a = 17.6490(3) Å, b = 17.9982(2) Å, c = 7.39329(12) Å, β = 116.0655(19)°, V = 2109.63(5) ų, Z = 1) is studied by the single crystal X-ray diffraction analysis under ambient conditions and also upon compression to 4 GPa in penetrating (water-containing) and non-penetrating (paraffin) media. Compression of Ksubstituted clinoptillolite in a water:ethanol (1:1) mixture results in its additional hydration: inclusion of 2.2 additional H₂O molecules into the structure at the initial stage. Upon further compression the H₂O concentration increases by two molecules. This is caused by additional occupancy of partially vacant H₂O sites. The cation environment practically does not change during overhydration. Changes in the coordination polyhedra of cations during compression in paraffin are reduced to a small (0.02-0.1 Å) decrease in bond lengths. Distinctions in the degree of hydration of the K-form upon compression in penetrating and non-penetrating media are manifested in the features of the compressibility of the compound.