N2O catalytic decomposition on electrodeposited Rh-based open-cell metallic foams

The present article reports on Rh-containing hydrotalcite (HT) derived catalysts coated on the surface of opencell FeCralloy foams. The structured catalysts were prepared by in situ synthesis of Rh/Mg/Al HT precursors through electrodeposition followed by calcination. For comparison purposes, powder catalysts with analogous compositions were obtained by coprecipitation. The catalytic activity in N2O decomposition (deN2O) over structured and pelletized catalysts was investigated in absence and presence of inhibitors (O2+NO) by keeping similar Rh loading and reaction conditions. Furthermore, stability of the structured catalysts was investigated.A Rh/Mg/Al HT-derived film uniformly coated the surface of the foam. The deN2O performance over both structured and pelletized catalysts was comparable for constant Rh loading in the catalytic bed, though lower activation energy was obtained for the structured catalyst. The coating was stable after a 24 h test at 475 °C in presence of O2 and NO, while rhodium oxide was reduced to Rh0 (2.0 ± 1.1 nm). Due to a low amount of active phase in the thin catalytic coating, the conversion steadily decreased during the first 20 h of time-on-stream from 60 until a constant 51% reaching stable level.