Insights into the Role of Copper and Cobalt in Mg/Al Mixed Oxide Catalysts in the Guerbet Reaction: An Atomistic Perspective

The production of n-butanol and other high-molecular-weight alcohols is feasible through the Guerbet reaction using ethanol (EtOH) as a feedstock. Previous studies have demonstrated that the rate-determining step of this reaction is the dehydrogenation of EtOH to produce acetaldehyde (AcH). For this transformation, hydrotalcite-derived catalysts are particularly noteworthy due to their tunable acid–base properties and the relative simplicity of their synthesis. Therefore, we evaluated the catalytic properties of Mg/Al, Cu–Mg/Al, and Co–Mg/Al hydrotalcite-derived mixed oxides (MOx) for EtOH dehydrogenation, unraveling the role of copper and cobalt in the stability of reaction intermediates. Our results suggest that the incorporation of copper into the MOx framework enhances EtOH dehydrogenation by stabilizing key intermediates. This effect is attributed to the higher reducibility of the copper cations, as well as enhanced charge delocalization that modifies the local acid–base properties. Furthermore, copper undergoes segregation, which facilitates the stabilization of certain intermediates. In contrast, cobalt does not introduce significant changes to the catalytic properties of the Mg/Al oxide.