Novel Rh-based structured catalysts for the catalytic partial oxidation of methane

Novel Rh-based structured catalysts were prepared by the electrosynthesis of Rh/Mg/Al hydrotalcite-type (HT) precursors on a FeCrAlY foam. The catalysts obtained by the calcination of HT compounds were investigated in the catalytic partial oxidation (CPO) of CH4. The effects of the electrosynthesis conditions (potential and pH of the plating solution) on the surface morphology and chemical composition of the samples as well as on the catalytic activity were investigated. The control of the pH of the solution favoured the precipitation of Rh as hydroxide rather than of metallic particles, whereas the potential applied determined the pH value reached near to the foam. By increasing the cathodic potential from −1.2 to −1.3 V, but keeping the synthesis time constant (1000 s), the required conditions to obtain HT precursors were achieved faster and, therefore, a larger amount of them precipitated. Due to the different coverage and chemical nature of the electrosynthesized species, catalytic performances depended on the synthesis conditions, the best values being achieved by the catalyst obtained from the HT precursor prepared at −1.3 V for 1000 s.