Promoting effect of solvent on Cu/CoO catalyst for selective glycerol oxidation under alkaline conditions

Cu/CoO catalysts were employed for the selective oxidation of glycerol in the aqueous phase under basic conditions. The effect of the solvent on the catalytic performance was investigated and the impact on the catalyst was thoroughly elucidated. Detailed characterization of the catalysts by HR-TEM, XRD, and XPS analysis before and after the reaction revealed that the addition of co-solvents (ethanol, n-propanol, or tert-butanol) drastically altered the catalyst properties. In particular, the amount of the catalytically active CoO(OH) phase generated during the reaction depends on the co-solvent used. Generally, the co-solvent has a beneficial effect on the catalytic activity and improves the glycerol conversion by a factor of up to 1.8, which could be linearly correlated to the ET(30) solvent polarity

In-situ Investigations of Co@Al₂O₃ Ammonia Decomposition Catalysts: The Interaction between Support and Catalyst

Cracking of ammonia, a hydrogen carrier with high storage capacity, gains increasing attention for fuel cell systems for heavy load transportation. In this work, we studied the influence of metal loading and synthesis temperatures on the properties of Co@Al2O3 catalysts. The combination of in situ bulk characterization methods with in situ surface spectroscopy provides insights into the structure-property relation of the Co catalyst on the γ-Al2O3 support. At too high temperatures, the formation of CoAl2O4 during synthesis or during the catalytic reaction itself results in inactive mixed metal aluminium spinels which do not contribute to the catalytic reaction. The amount of ‘active’ Co catalyst thus varies significantly as well as its catalytic activity. The latter is correlated to the size of the reduced Co particles on the alumina support. The experiments also highlight that the state of the catalyst changes after reaction which strongly emphasizes the necessity of in situ studies