Highly selective adsorption of CO over CO2 in a Cu(I)-chelated porous organic polymer

- Cu(I) species were stably chelated to nitrogen atoms in SNW-1 by mixing with a CuCl solution.
- Cu(I)-chelated SNW-1 shows selective CO adsorption over CO2 due to the π-complexation of CO with Cu(I).
- 1.3Cu(I)@SNW-1 exhibits good cyclic CO/CO2 separation performances under dynamic mixture flow conditions.
- 1.3Cu(I)@SNW-1 exhibits a good stability under exposure to atmospheric air.

Cu(I) species were successfully chelated to nitrogen atoms in a nitrogen-rich porous organic polymer (SNW-1) by mixing with a CuCl solution (Scheme 1). Although pristine SNW-1 adsorbs CO2 better than CO, Cu(I)-incorporated SNW-1 (nCu(I)@SNW-1) shows selective CO adsorption over CO2 because of the π-complexation of CO with Cu(I). To the best of our knowledge, this is the first CO/CO2 selectivity observed for POP-based materials. 1.3Cu(I)@SNW-1 exhibits high CO/CO2 selectivity (23) at 1 bar and a large CO working capacity (0.6 mmol/g) at 0.1-1 bar. Moreover, the breakthrough and thermogravimetric experiments show that 1.3Cu(I)@SNW-1 can effectively separate CO from CO2 under dynamic mixture conditions and can be easily regenerated under mild regeneration conditions without heating the column. Furthermore, 1.3Cu(I)@SNW-1 exhibited a good stability under exposure to atmospheric air for 3 h or 9 h. These results suggest that chelating Cu(I) species to a nitrogen-rich porous organic polymer can be an efficient strategy to separate and recover CO from CO/CO2 mixtures.

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