Humidity-swing mechanism for CO2 capture from ambient air

Abstract

A humidity-swing polymeric sorbent captures CO₂ from ambient air at room temperature simply by changing the humidity level. To date there has been no direct experimental evidence to characterize the chemical mechanism for this process. In this report we describe the use of solid-state NMR to study the humidity-swing CO₂ absorption/desorption cycle directly. We find that at low humidity levels CO₂ is absorbed as HCO₃⁻. At high humidity levels, HCO₃⁻ is replaced by hydrated OH⁻ and the absorbed CO₂ is released.