Covalent-organic polymers for carbon dioxide capture

Abstract

Reducing anthropogenic carbon dioxide emission has become an urgent environmental and climate issue of our age. Here, a series of covalent-organic polymers (COPs) are synthesized, and the adsorption properties of these COPs for H 2, CO 2, CH 4, N 2 and O 2 are studied. The H 2 uptake of COP-2 reaches 1.74 wt% at 77 K and 1 bar, which is among the highest reported uptakes in the field of microporous organic polymers under similar conditions, and CO 2 and CH 4 adsorption capacities are 594 mg g -1 and 78 mg g -1, respectively, at 298 K and 18 bar. Then, based on the single component isotherm, the dual-site Langmuir-Freundlich (DSLF)-based ideal adsorption solution theory (IAST) is used to predict the selectivity of the COP materials for post-combustion (CO 2-N 2) and pre-combustion (O 2-N 2) gas mixtures. The IAST predicted results indicate that COP-1 exhibits significantly higher selectivity compared to COP-2, 3 and 4, due to its smaller pore size. In particular, the adsorption selectivity of COP-1 for the CO 2-N 2 mixture reaches 91 at a CO 2:N 2 ratio of 15:85 at 298 K and 1 bar, and 2.38 for the 21:79 O 2-N 2 mixture at 298 K and 1 bar. Furthermore, these COPs also show robust properties for the removal of CO 2 from natural gas. The adsorption selectivity of COP-1 for CO 2-CH 4 is in the range of 4.1-5.0 at a CO 2:CH 4 ratio of 15:85 at 0 < P < 40 bar. © 2012 The Royal Society of Chemistry.