Potential of Branched Polymers in the Field of Gas Absorption: Experimental Gas Solubilities and Modeling

In this work, the potential of low-viscous branched polymers for gas separation applications such as CO 2 absorption from flue gas is examined. Carbon dioxide and nitrogen solubilities are measured at low pressures for linear and branched polyethers, hyperbranched polyesters, and polyamines such as a polyamidoamine and a polyethylene imine as well as in their aqueous solutions. The results are reported in terms of Henry constants in the temperature range T = 310−370 K. The densities of the pure polymers and their aqueous solutions are measured between T = 293.15 and 363.15 K. The selectivities of the polymers for CO 2 /N 2 and the enthalpies of absorption at infinite dilution are determined. The group-contribution method UNIFAC-FV is applied to the CO 2 solubilities in polyethers and the hyperbranched polyester. It has been shown that branched polymers are promising candidates for gas absorbents with a high capacity for CO 2 and with large selectivities. The UNIFAC-FV model is able to predict the CO 2 solubilities in the investigated polymers.