Holey Graphitic Carbon Derived from Covalent Organic Polymers Impregnated with Nonprecious Metals for CO2 Capture from Natural Gas

Natural gas (NG), as a renewable and clean energy gas, is considered to be one of the most attractive energy carriers owing to its high calorific value, low price, and less pollution. Efficiently capturing CO2 from NG is a very important issue since CO2 reduces energy density of natural gas and corrodes equipment in the presence of water. In this study, the authors use holey graphene-like carbon derived from covalent organic polymers (COP) impregnated with nonprecious metals, i.e., COP graphene, as highly efficient separation materials. The dual-site LangmuirFreundlich adsorption model based ideal absorbed solution theory is applied to explore the adsorption selectivity. The experimental results along with first principles calculations show Mn-impregnated COP graphene exhibits greater CO2/CH4 selectivity than Fe and Co impregnated materials. Particularly, the selectivity of CCOPPMn reaches 11.4 at 298 K and 12 bars, which are much higher than those in many reported conventional porous materials and can be compared to the highest separation performance under similar condition. Importantly, all the three COP graphene show remarkably high regenerability (R > 77%), which are much better than many reported promising zeolites, active carbon, and metal organic frameworks. Accordingly, COP graphene are promising cyclic adsorbents with high selectivity for separation and purification of CO2 from natural gas.