MOLECULAR SIMULATION OF ADSORPTION AND DIFFUSION IN VPI-5 AND OTHER ALUMINOPHOSPHATES

Adsorption isotherms for argon in AlPO4-5, AlPO4-8, and VPI-5 were simulated at 77 and 87 K using the grand canonical Monte Carlo method. The shapes of the isotherms were found to be in qualitative agreement with published experimental data; however, the maximum predicted values of the adsorption were higher than the experimental values. Only an unphysical choice of parameters could bring about agreement. Possible causes of this discrepancy are discussed. We also report isosteric heats of adsorption obtained from the GCMC results and diffusion coefficients for VPI-5 obtained from molecular dynamics.