G. Larsen, T. Guin, K. McDonald, C. Malone, J. Folkert
Savannah River National Laboratory,
United States
Keywords: deuteration, polymers, polyolefin, PFAS replacement
Summary:
Fully deuterated organic materials, such as polymers, have unique properties compared to normal protiated materials and can enable new avenues of scientific discovery and materials performance. This is because protium (H) and deuterium (D) have the largest relative mass ratios of any isotopes, which significantly affects kinetics (kinetic isotope effect) and shifts vibrational energies. Additionally, the C-D bond has improved stability compared to the C-H bond. However, deuterated organics are extremely expensive and only available in small quantities, if available at all. This is because traditional methods for deuterated organic syntheses rely on D2O chemistry to build up larger molecules from precursors and monomers – an expensive and laborious process that is constrained by known chemical pathways. We have recently demonstrated record-breaking catalytic deuteration of long chain aliphatic molecules, by achieving >99% deuteration of a mineral oil, polypropylene, and polyethylene with minimal product degradation, where the previous best result is only 54%. The critical element of our success was the use of a flow-through system. This is because hydrogen isotope exchange is an equilibrium-driven process. By continuously purging the reactor vessel, the deuterium partial pressure can be controlled to >99%, driving the reaction faster and to much higher deuteration levels. Deuterium recovery is a critical step toward making this process scalable. In this presentation, we describe the integration of catalytic isotope exchange with continuous deuterium recovery.