Passive autocatalytic recombination of hydrogen on a Pt/Al2O3-coated metal foam: Experimental evaluation and CFD modelling

Pt/Al 2 O 3 -coated Al foams were tested for the passive autocatalytic recombination of H 2 . The characterisation of the washcoat surface confirmed the uniform distribution of Pt and Al 2 O 3 over the entire washcoat surface. Transmission electron microscopy results revealed a slight increase in particle size from 3.8 to 6.2 nm after prolonged reaction. High H 2 conversions of 57–89% are achieved and the catalyst activity is maintained for >480 h on stream. The performance of the foam-based catalyst bed is similar to that of plates but surpasses that of catalyst pellets. Temperatures recorded at the hottest spots on the foam surface reach a maximum of only 393 °C at the highest H 2 inflow. Computational fluid dynamics simulations were performed on the actual foam geometry obtained using computed tomography. The simulations demonstrate the importance of thermal radiation in the model. There is good agreement between results of experimental H 2 conversions and maximum combustion temperatures. • Efficiency of the foam-, plate-supported and pellet catalysts were compared experimentally. • Pt/Al₂O₃ foams demonstrated rapid start-up behaviour and high catalytic activity. • Computed tomography and CFD methods were combined and velidated. • CFD simulations revealed the importance of accounting for thermal radiation model. • Results showed high H₂ conversion rates within the catalytic foam region.