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Identifying the ideal thermodynamics of non-stoichiometric oxygen-carrier materials for chemical looping water-gas shift

Lookup NU author(s): Selim Ungut, Professor Ian MetcalfeORCiD, Dr Wenting HuORCiD

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This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


Abstract

With the growth in importance of H2 both industrially and as a potential energy vector along the pathway to achieving future environmental sustainability, there is an increasing need for cleaner and more efficient methods of H2 production. One promising short-term solution is to perform the water-gas shift reaction for H2 production in a chemical looping reactor to produce separate H2 and CO2 streams, thereby reducing equipment size and the cost of downstream CO2 separation. Non-stoichiometric perovskite oxides have been identified as promising oxygen carrier materials (OCMs) for the chemical looping water-gas shift (CLWGS) process as they can be engineered to allow rapid oxygen uptake kinetics, and also benefit from a thermodynamic advantage allowing higher conversions than that of conventional mixed feed reactor systems at the same temperature. The relationship between the oxygen non-stoichiometry of the solid OCM and the equilibrium oxygen partial pressure of the gas phase streams plays an important role in determining the gas conversions and usable oxygen capacity of the OCM. In this work, an optimal relationship between the two material properties in a thermodynamically limited system is proposed, and an equilibrium packed-bed reactor model is used for validation. The effect on conversions was investigated by varying the thermodynamics of the non-stoichiometric material relative to the proposed optimal case. More generally, an analogue of the pinch analysis can be used to analyse chemical looping water-gas shift reactions and similar processes.


Publication metadata

Author(s): Ungut MS, Metcalfe IS, Hu W

Publication type: Article

Publication status: Published

Journal: Reaction Chemistry & Engineering

Year: 2025

Volume: 10

Issue: 4

Pages: 800-809

Online publication date: 15/01/2025

Acceptance date: 07/01/2025

Date deposited: 30/01/2025

ISSN (electronic): 2058-9883

Publisher: Royal Society of Chemistry

URL: https://doi.org/10.1039/D4RE00454J

DOI: 10.1039/D4RE00454J

Data Access Statement: The MATLAB scripts used to generate results presented in this work can be found at https://doi.org/10.25405/data.ncl.27055339. The version of MATLAB employed for this study is version R2021b.


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Funding

Funder referenceFunder name
CiET1819\2\57
DTP
Engineering and Physical Sciences Research Council
EP/N509528/1
EP/P007767/1
EP/P024807/1EPSRC
Royal Academy of Engineering

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