Insights into Selective Gas Sorbent Functionality Gained by Using Time-Resolved Neutron Diffraction

An understanding of the atomic-scale interactions between gas sorbent materials and their molecular guests is essential for the identification of the origins of desirable function and the rational optimization of performance. However, characterizations performed on equilibrated sorbent-guest systems may not accurately represent their behavior under dynamic operating conditions. The emergence of fast (minute-scale) neutron powder diffraction coupled with direct, real-time quantification of gas uptake opens up new possibilities for obtaining knowledge about concentration-dependent effects of guest loading upon function-critical features of sorbent materials, including atomic structure, diffusion pathways, and thermal expansion of the sorbent framework. This article presents a detailed investigation of the ultramicroporous metal-organic framework [Cu₃ (cdm)₄ ] as a case study to demonstrate the variety of insights into sorbent performance that can be obtained from real-time characterizations using neutron diffraction.