Sorbent-based oxygen separation with YBC114 for energy storage systems

Experimental and simulated O 2 sorption breakthrough curves at different temperatures. • Successfully evaluated YBaCo 4 O 7+δ (YBC114) – based oxygen separation process. • Collected comprehensive design data in TGA, breakthrough, and cyclic experiments. • Identified optimum adsorption (300 °C) and desorption (500 °C) conditions. • Demonstrated stable performance of YBC-114 in thermal swing adsorption cycles. • Established design procedures for the YBC-based oxygen separation system. In this work, we aimed to design, build, and evaluate an oxygen separation system to provide an inert sweep gas with low oxygen partial pressure (p O2 ) to redox-active thermochemical energy conversion reactors for a range of applications, including two-step redox cycles for thermochemical energy storage, water splitting, and carbon-dioxide splitting. The separation is based on an oxygen-selective sorbent, YBaCo 4 O 7+δ (YBC114), which has excellent oxygen sorption and desorption properties demonstrated in our previous work. The oxygen separation performance of YBC114 was comprehensively studied by thermogravimetric analysis, sorption breakthrough experiments, and temperature swing sorption - desorption cycles. The results reveal that YBC114 can produce inert sweep gas with an oxygen concentration of less than 100 ppmv for at least 20 min during the thermal swing adsorption (TSA) cycle with the current sorption bed configuration, and the performance is consistent from cycle to cycle. The optimal sorption and desorption temperatures for the TSA process with YBC114 are determined to be 300 °C and 500 °C, respectively. Although challenges remain for the current separation system (e.g., high sorption temperature and slow kinetics), this study demonstrates the potential to use the oxygen-selective sorbent to produce an inert sweep gas, the feasibility of the oxygen separation concept, and guides new sorbent material development to make this application economically practical. A simple procedure is described for designing the YBC114 oxygen separation process.