Increasing the CO2/N2 Selectivity with a Higher Surface Density of Pyridinic Lewis Basic Sites in Porous Carbon Derived from a Pyridyl-Ligand-Based Metal-Organic Framework

The development of functional porous carbon with high CO2/N-2 selectivity is of great importance for CO2 capture. In this paper, a type of porous carbon with doped pyridinic sites (termed MOFC) was prepared from the carbonization of a pyridyl-ligand based MOF. Four MOFCs derived from different carbonizing temperatures were prepared. Structural studies revealed high contents of pyridinic-N groups and nearly the same pore-size distributions for these MOFCs. Gas-sorption studies revealed outstanding CO2 uptake at low pressures and room temperature. Owing to the high content of pyridinic-N groups, the CO2/N-2 selectivity on these MOFCs exhibits values of about 40-50, which are among the top values in carbon materials. Further correlation studies demonstrated that the CO2/N-2 selectivities show a positive linear relationship with the surface density of pyridinic-N groups, thus validating the synergistic effect of the doped pyridinic-N groups on CO2 adsorption selectivity.