Oxidative Steam Reforming of Ethanol on Supported Rh Nanoclusters.(1/2)

We propose to investigate oxidative steam reforming (OSR, C2H5OH + H2O + O2 → H2 + CO2) of ethanol onsupported Rh nanoclusters. As the reaction provides an alternative approach to obtain renewable hydrogenand as ethanol can be readily extracted from fermentation of biomass such as sugarcane and corn, it is ofinterest to chemical industry and fuelcell applications. The supported Rh clusters are chosen as Rh-basedcatalysts have exhibited the best performance in terms of ethanol-conversion efficiency and hydrogenselectivity. To reveal the mechanism of the OSR of ethanol, earlier studies concentrated on the ethanoldecomposition through the formation of surface oxametallacycle (CH2CH2O*) and the following C-C bondscission. The role of surface oxygen and hydroxyl (-OH) from dissociated molecular oxygen and water ishowever neglected and not investigated. The present investigation is aimed to shed light on the effects ofsurface oxygen and hydroxyl on the entire processes and also the correlation between the effects and thecatalyst’s structures. The investigation encompasses model-system studies, DFT calculations andreal-catalysts experiments. The model system studies are conducted under ultrahigh vacuum conditions withvaried surface probe techniques. The reactions on Rh clusters supported on Al2O3/NiAl(100) andgraphene/Pt(111) are characterized. The DFT calculations and real-catalysts experiments are performed bythe collaborator. The DFT calculations give the activation barrier and reaction energy for each step of thereaction on varied sites on the clusters. The computed results together with the experiments with real-worldcatalysts are compared to those from model-system experiments to illuminate the oxygen and hydroxyleffects in the reforming reaction and their structural dependence.