Combined CO2-philicity and ordered mesoporosity for highly selective CO2 capture at high temperatures

Abstract

Various dry sorbents have been lately introduced as promising media to capture carbon dioxide (CO2). However, it is still desirable to further improve their performance in diverse aspects, and high temperature selectivity of CO2 over other gases is clearly one of them. Here, we report a co-assembly approach to turn nonporous melamine resin to a highly ordered mesoporous polymeric network (space group: Im (3) over barm) containing high nitrogen content (similar to 18 at%). This mesoporous network shows anomalously increasing CO2/N-2 selectivity with temperature rise, with the selectivity at 323 K reaching 117 (Henry method). This selectivity behavior is attributed to a combined effect of the high nitrogen content allowing for high binding affinity with CO2 and well-defined mesopores (2.5-2.9 nm) accelerating release of N-2 with temperature rise. The given orthogonal approach suggests a new direction in designing dry sorbents with excellent selectivities at high temperatures.