Neutron powder diffraction study of the dehydration of zeolite N

Abstract

Zeolite N is pseudo-tetragonal with an EDI-type structure. The orthorhombic cell at 293 K has a=989.8(2), b=989.1(2), c=1308.5(1) pm, space group 1222 and Z=1, for the composition K12Al10Si10O40Cl 2·8H2O. Neutron diffraction powder patterns were analyzed for data collected at 5 K and in the temperature range 293-623 K. Thermal analysis shows that complete dehydration takes place in the temperature range 373-623 K, which is consistent with the observed reduction of background from incoherent scattering reduction and changes in occupation numbers. The removal of water is connected with rearrangement of the chlorine and potassium atoms, the driving force probably being the strive for acceptable coordination of the salt-like components.