Establishing upper bounds on CO2 swing capacity in sub-ambient pressure swing adsorption via molecular simulation of metal–organic frameworks

Abstract

Swing capacity is a key performance metric for processes designed to capture CO₂ by pressure swing adsorption (PSA). Sub-ambient operation of PSA units enables large changes in CO₂ swing capacity, and can be economically viable when coupled with heat integration and power recovery. Here, we examine what upper bounds on CO₂ swing capacity exist via molecular simulation of a large collection of metal–organic frameworks (MOFs). As has been observed previously for zeolites, the materials with the largest swing capacity at a given temperature have large pore volumes and heats of adsorption within a narrow range of optimal values. A number of materials are identified with swing capacities up to 40 mol kg⁻¹ using a pressure swing from 0.1 bar to 2.0 bar.