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A lab-scale solar reactor, equipped with a porous CeO 2 structure with dual-scale porosity for CO 2 and H 2 O splitting, has been simulated and validated using available experimental results. The validated model was then used to scale-up the geometry to the MW scale and to investigate the benefits in the studied reactor. The larger reactors displayed partially better performance, but their potential was limited by the restricted thickness of the porous structure during scaling-up. This restriction accelerated the temperature uniformity in the CeO 2 volume, followed by saturation and a steady-state effect with reduced O 2 production. The validated model can be used for further reactor optimization, which should be addressed in combination with a dedicated plant design study for continuous carbon-neutral fuel production.

Computational Fluid Dynamics (CFD) models are a valuable tool for design, optimization, and scaling-up of fixed bed chemical reactors. However, the realistic representation of the catalytic bed structure and the mesh quality of the 3D geometry is of paramount importance to improve the accuracy of CFD models. For the former, computed tomography (CT) is a non-destructive method to map and generate the internal structure of actual fixed bed reactors, formed by catalytic particles produced by sieving, thus directly coupling experiments with CFD models. Due to the local topological complexity of these beds, however, meshing their entire volume would lead to exhaustive computational demands. To reduce these, a suitable sample section should be selected, which respects the bulk and radial porosity of the full bed as accurately as possible. Three distinct sample sections were quantified here for their accuracy, identifying that, due to the highly heterogeneous nature of the full beds, sample selection is case sensitive. A selected section was then meshed, and its hydrodynamic profile resolved, to evaluate its mesh independency. The results highlight the importance of choosing a suitable bed section and mesh size to reduce the computational demands, minimise the computational errors, and achieve the desired level of solution detail.

The kinetics of methanol synthesis from a mixture of CO2/CO/H2 have been widely studied in the literature. Yet the role of direct CO hydrogenation is still unclear, in terms of...

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