EFFECT OF LATTICE-RELAXATION ON CATION-EXCHANGE IN ZEOLITE-A USING COMPUTER-SIMULATION

Atomistic simulation techniques based on the Born model of ionic solid s have been used to investigate adsorption and ion exchange of Ba2+, S r2+, Ca2+, Cd2+, Ni2+, Co2+, Cs+, K+, and Na+ in dehydrated zeolite A. This work has shown that relaxation of the framework greatly affects the position of the most stabile exchangeable cation sites. The result s have considerable consequences for simulation studies showing that s imulations are meaningful only if the framework is allowed to relax fr eely. The aluminum content in the zeolite framework was found to influ ence the size of the ring structures, which in addition influences the , exchangeable cation positions. The simulation results have identifie d stable adsorption sites for the exchangeable cations, which show goo d agreement with experimental crystallographic data. This indicates th e viability of using atomistic simulation to probe the structure, stab ility, and diffusivity in zeolites.