Abstract:
The reverse water gas shift (RWGS) reaction is a key pathway for CO2 utilization, particularly within Power-to-X process chains aimed at sustainable fuel and chemical production. Countercurrent chemical looping (CL-RWGS) using non-stoichiometric oxides can overcome equilibrium limitations of conventional RWGS reactors, enabling significantly higher CO2 conversions. However, modeling the limiting performance of such systems is challenging due to their multiphase nature and coupled spatial and temporal variation in chemical composition. In this work, we present a discretized batch equilibrium model that simulates CL-RWGS reactors as a series of localized equilibrium exchanges between gas and solid elements. The model is numerically stable, computationally efficient, and free of kinetic source terms, making it well-suited for parametric studies and system-level integration. It is validated against established convection–diffusion models and shown to predict reasonable upper bounds on experimental results. Application of the model to a range of oxygen carrier materials identifies cerium–zirconium solid solutions, particularly Ce0.80Zr0.20O2, as a promising class offering superior oxygen storage characteristics compared to state-of-the-art La0.6Sr0.4FeO3. This framework provides a robust platform for materials screening, reactor sizing, and performance optimization in chemical looping systems. The model implementation is available as open-source software to support further research and development.
B. Bulfin, R. Ghotkar, A. Lidor,Thermodynamic modeling of countercurrent chemical looping reverse water gas shift process for redox material screening,Chemical Engineering Journal,Volume 525,2025,170505,ISSN 1385-8947, https://doi.org/10.1016/j.cej.2025.170505
