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Published April 17, 2014 | public
Journal Article

Efficient Splitting of CO_2 in an Isothermal Redox Cycle Based on Ceria

Abstract

An isothermal thermochemical cycle to split CO_2 based on nonstoichiometric reduction and oxidation of ceria is demonstrated. Carbon monoxide is produced via an oxygen partial pressure swing by alternating inert sweep gas and CO_2 flows over the ceria. The rates of reduction and oxidation at 1500 °C in a porous ceria particle bed are measured for sweep gas and CO_2 flow rates from 50 to 600 mL min^(–1) g^(–1) and analyzed to identify cycle operating conditions (gas flow rates and reduction and oxidation durations) that maximize process efficiency. For a solar reactor assumed to operate at 3000 suns concentration and with 90% of the sensible heat of the gases recovered, the optimal cycle uses 150 mL min^(–1) g^(–1) sweep gas and 50 mL min^(–1) g^(–1) CO_2 at reduction and oxidation periods of 100 and 155 s, respectively. This cycle is demonstrated in an IR imaging furnace over 102 cycles, yielding a stable average rate of CO production of 0.079 μmol s^(–1) g^(–1) and a projected reactor efficiency of 4%. The optimal conditions apply at large scale if the flow rates are scaled in proportion to the ceria mass.

Additional Information

© 2014 American Chemical Society. Received: December 17, 2013; revised: March 12, 2014; published: March 14, 2014. The research was supported by the U.S. Department of Energy, through ARPAe Contract DE-AR0000182, and the University of Minnesota Initiative for Renewable Energy and the Environment. We thank Bernard Kim for preparing the porous ceria monoliths and Nicholas D. Petkovich for the scanning electron micrograph of the porous ceria microstructure.

Additional details

Created:
August 20, 2023
Modified:
October 26, 2023