Molecular dynamics simulations of binary mixtures of methane and hydrogen in zeolite A and a novel zinc phosphate

Molecular dynamics simulations have been used to study binary mixtures of h ydrogen and methane in two molecular sieve structures, zeolite NaA and a no vel zinc phosphate molecular sieve, Na3ZnO(PO4)(3), which has a pore size t uned to light gas separations. Simulations were run at high temperature, T = 500 degreesC. Equimolar mixtures of methane and hydrogen in both molecula r sieve structures were simulated at loadings of 2-16 molecules per unit ce ll. Self-diffusion coefficients were calculated using the Einstein relation ship. Hydrogen was found to have higher self-diffusion coefficients than me thane in both the molecular sieve structures under study. However, in the z inc phosphate molecular sieve the methane remained immobile, allowing for p urification and separation of hydrogen, whereas in Zeolite A the methane ex perienced appreciable cage-to-cage motion.