Cross-Scale Catalyst\nModeling Applied to H<sub>2</sub> Storage and Release via Formic Acid

We propose the Systems-to-Atoms (S2A) modeling framework\nthat integrates\nthe kinetics of reaction chemistry and structural configurations across\nvarious length scales with the aim of establishing a versatile template\nfor multiscale modeling of reactive flow problems and to predict the\noperando activity of catalyst materials. The approach encompasses\na microkinetic model to analyze surface reactions on individual facets\nof catalyst nanoparticles coupled with the computation of average\nsurface reaction rates for catalyst nanoparticles of specific size\ndistributions. Macro-homogeneous surface reaction kinetics are derived\nas a function of catalyst loading and used as input parameters for\nthe continuum-scale reactor model. The cross-scale framework enables\nthe optimization of catalyst utilization through reactor design and\noperating\nstrategy. To demonstrate the framework, we studied the storage and\nrelease of hydrogen from formic acid, a promising liquid organic hydrogen\ncarrier (LOHC), over Pd, Pt, and Cu catalysts. The framework predicts\nobserved trends in formic acid dehydrogenation activity for catalysts\nwith comparable weight loadings and metal particle diameters, demonstrating\nsatisfactory quantitative alignment. Finally, the seamless transmission\nof parameter uncertainties between scales is also discussed.