(606b) The Influence of Amine Type and Operating Conditions on the Kinetics and Mechanisms of CO2 Facilitated Transport across Amine-Functionalized Polymeric Membranes

Reactive amines in polymeric facilitated transport membranes (FTMs) facilitate CO₂ transport across the membrane to give rapid and selective CO₂ separation from mixed gas streams. The performance of amine-based FTMs depends on the structure/type of the amine functional group as well as the operating conditions, particularly the relative humidity. However, the influence of the amine type and operating conditions on the fundamental kinetics and mechanisms of amine-facilitated CO₂ transport are currently not well understood on the molecular level, which hinders rational design of high-performance FTMs. In this talk, I will discuss our efforts to elucidate the effects of amine type and operating conditions on CO₂ facilitated transport using operando spectroscopic characterization of amine-functionalized membranes under operating conditions to identify CO₂ transport intermediates (e.g., carbamate, bicarbonate) and mathematical modeling of experimentally measured CO₂ permeation rates to extract fundamental kinetic and thermodynamic parameters associated with CO₂ facilitated transport. I will examine the kinetics and mechanisms of CO₂ transport across amine-based FTMs with different amine types, including primary, secondary, tertiary, quaternary, and pyridinic, and under different operating conditions, including the effects of humidity and under extremely dilute CO₂ concentrations. I will show that the kinetics and mechanisms of CO₂ facilitated transport are highly sensitive to the structure of the amine type and to the operating conditions. The molecular-level insights obtained from this new kinetic modeling and operando methodology will enable a more rational design of membranes for CO₂ separation than conventional membrane testing with ex-situ characterization approaches.