Selective separation of nitrogen (N-2) from methane (CH4) is highly significant in natural gas purification, and it is very challenging to achieve this because of their nearly identical size (the molecular diameters of N-2 and CH4 are 3.64 angstrom and 3.80 angstrom, respectively). Here we theoretically study the adsorption of N-2 and CH4 on B-12 cluster and solid boron surfaces alpha-B-12 and gamma-B-28. Our results show that these electron-deficiency boron materials have higher selectivity in adsorbing and capturing N-2 than CH4, which provides very useful information for experimentally exploiting boron materials for natural gas purification. (C) 2013 Elsevier Ltd. All rights reserved.