Porous Carbon Nanotube Membranes for Separation of H2/CH4 and CO2/CH4 Mixtures

Porous carbon nanotubes, which are single-walled carbon nanotubes having tailored pores in their sidewalls, are proposed as potential membrane materials for separating gas mixtures with high selectivity and high permeance. We present both quantum mechanical calculations and classical statistical mechanical calculations with empirical potentials showing that porous carbon nanotubes having the correct pore size can very effectively separate mixtures of H2/CH4 and also of CO2/CH4. In each of these mixtures, CH4 is effectively prevented from entering the pore due to size exclusion. These porous carbon nanotubes could be used in mixed matrix polymer membranes to increase both the permeance and the selectivity for targeted gas mixtures.