Molekulare simulation von adsorptionsvorgangen in kohlenstoff-nanorohrchen

A study was made of the adsorption of methane, tetrafluoromethane(CF₄), and their mixtures in carbon nanotubes using molecular simulation. In particular, the effects of pore radius, pressure, temperature, and mixture composition on the adsorption isotherms and the radial distribution of the molecules were studied. The selectivity of methane at a mole fraction of 0.4 was illustrated as a function of the pore radius. In pores with a radius of 5.1 A., the selectivity with respect to methane at all pressures was less than one, i.e., CF₄ was enriched in the pores. At larger pore radiuses and pressures of ~ 200 bar, the selectivity increased to > 1; at 100 bar and up to ~ 9 A. was > 1, and then again dropped to < 1. At ~ 6.3 A. , at all pressures the selectivity was maximum. At this radius two methane molecules could be accomodated beside each other in the pore. With the choice of pore radius thus an effective control of selectivity is possible.