Activity of Fe2O3/CeO2-Al2O3 catalysts/oxygen carriers in a fluidized bed chemical looping process for blue hydrogen production

Abstract

The transition to achieving net zero emissions by 2050 requires a significant increase in green hydrogen, produced using renewable energy and emitting no carbon. As different actors are working on the deployment of technologies to produce green hydrogen at large scale a technological bridge is necessary for the shift from gray hydrogen to green hydrogen in the new energy paradigm. Extensive research is underway to enhance hydrogen production and reduce production costs, particularly in the technology of blue hydrogen production. Chemical looping technology is one innovation developed to reduce the costs by separate CO₂ in situ without requiring a separation unit. The success of the chemical looping process depends on selecting the ideal oxygen carrier to facilitate the reaction. Previous research has indicated that iron possesses the desired chemical and physical attributes, making it cost-effective and easily obtainable. Additionally, determining the appropriate amount of iron added to Al₂O₃ as support is crucial for optimizing the reaction process and preventing the deactivation of the oxygen carrier. This study explores the effects of adding iron to a Ce-modified Al₂O₃ support in hydrogen production through chemical looping tested in a fluidized bed reactor. Research findings indicate that at a temperature of 650 °C, F20Ce-Al demonstrates more potential for reduction to the iron state in fuel reactors compared to F30Ce-Al, primarily due to the involvement of the water-gas shift reaction (WGSR) in the reaction using F20Ce-Al. During the operation of the steam reactor, it was observed that F30Ce-Al exhibited the highest hydrogen production among the tested oxygen carriers within the first 5–16 seconds. However, beyond 16 seconds, hydrogen production decreased due to agglomeration of the oxygen carrier during the reaction process. In contrast, F20Ce-Al demonstrated the best performance in H₂ production compared to the other oxygen carriers.