Methane separation and capture from nitrogen rich gases by selective adsorption in microporous Materials: A review

The rapid increase of natural gas consumption has induced imbalance between supply and demand of natural gas, and the continuous growth of methane emissions has severely exacerbated greenhouse effects and destroyed the atmospheric methane cycle. High-efficiency CH4 capture and separation from N-2 rich gases has become a significant challenge for the recovery and utilization of low-grade natural gas and also industrial tail gas, which was important for sustainable energy and environment and attracted much attention from both researchers and engineers in recent years. This review provides an overview of selective separation techniques for N-2 removal from natural gas including the benefits and drawbacks of these typical methods. Most notably, the review primarily outlines the progress of metal-organic frameworks, zeolites and activated carbons as superior adsorbents for separating CH4-N-2 mixtures in worldwide laboratories, respectively, with an emphasis on the relationship of the pore size, surface chemistry and composition of adsorbents with the CH4/N-2 selectivity and methane capacity. We also highlight the potential for the development of the new adsorbents with the best possible matching between aperture control and atomic-scale tuning of the composition for CH4 capture and separation from N-2 rich gases, and indicate that the MOFs possess both the advantages of activated carbons and zeolites and will become one of the most promising candidates for high-efficiency CH4 separation from N-2 rich gases in the future.