Neutron diffraction evidence of double interaction between NaY zeolite and ammonia and migration of Na+ ions upon ND3 adsorption

The crystal structure of NaY + ND3 has been determined at 20 K by powder neutron diffraction using Rietveld analysis. The cations were located at site I′ (8), site II (32) and at a third site (21) in the α-cage. This reveals a substantial migration of the cations from the site I, which is totally emptied, and the site I′ to large cages. The ND3 are in electrostatic interaction with the Na+-counter-ions and in hydrogen bonding interaction with the framework oxygen atoms. This double interaction is for the first time experimentally evidenced on cationic zeolite upon ammonia adsorption.