Computational Investigation on Adsorption and Diffusion of 4 Gas Molecules in High Pressure PPX Structure

Abstract

The adsorption and diffusion behaviour of 4 gas molecules in PPX was studied by grand canonical Monte Carlo (GCMC), molecular dynamics theory (MD) and COMPASS force field. The periodic structures and inner holes of PPX N, C and D were constructed with molecular mechanics (MM) method under 10 MPa, and the relevant structural parameters were determined. The equilibrium adsorption capacity of 4 gas molecules including N2, O2, H2O and CO2 were studied in different environmental temperature and pressure by GCMC method. The GCMC result is time-independent; it shows that the adsorption capacity is balanced under room temperature and atmospheric pressure. On the basis of above, the time-dependent result is calculated by MD method. The result shows that gas molecule is self-excited oscillation on certain position of PPX inner holes; its behaviour belongs to anomalous diffusion. This is same with the weak adsorption capacity results.