Aminopolymers are promising sorbent materials for direct air capture applications demonstrating efficient adsorption of atmospheric CO2 that can then be regenerated by exposure to elevated temperatures and steam. During regeneration the CO2 is released and captured for long term sequestration. However, the development of large-scale direct air capture technology is hindered by limited sorbent lifetime which drive up cost. Aminopolymers are susceptible to a variety of degradation mechanisms at the conditions required for regeneration: high temperatures, exposure to steam and oxygen, all of which limit CO2 adsorption capacity and diminish usable lifetime.
Understanding aminopolymer degradation mechanisms is an important step towards developing degradation mitigation strategies that will increase their lifetime. It is also important to develop techniques to aid in detection of when and how an aminopolymer sorbent has degraded. NMR is particularly suited for addressing these issues as it offers chemical information of degradation compounds and is sensitive to changes in their molecular dynamics.
This poster will show the degradation of aminopolymers detected by solid state 1H, 13C, 15N NMR as well as their impact on NMR relaxation parameters. These relaxation parameters can be detected using low field magnetic resonance techniques enabling a non-destructive method for identifying when the aminopolymer has reached its end of life.
This work was performed under the auspices of the US Department of Energy by LLNL under contract number DE-AC52-07NA27344.