Mechanistic investigation on ethanol‐to‐butadiene conversion reaction over metal oxide clusters

Abstract

Density functional theory (DFT) calculations were conducted to investigate mechanistic details of ethanol‐to‐butadiene conversion reaction over MgO or ZnO catalyst. We evaluated the Lewis acidity and basicity of MgO and ZnO and found that ZnO had the stronger Lewis acidity and basicity than MgO. Potential energy surfaces of ethanol‐to‐butadiene conversion, which included relevant transition states and intermediates, were computed in detail following the generally accepted mechanism reported in the literature, where such mechanism included ethanol dehydrogenation, aldol condensation, Meerwein‐Pondorf‐Verley reduction, and crotyl alcohol dehydration. DFT results showed that ethanol dehydrogenation was the rate‐limiting step of overall reaction when the reaction was catalyzed by MgO. Also, DFT results showed that ethanol dehydrogenation occurred more easily on ZnO than on MgO, where such a result correlated with the stronger Lewis acidity of ZnO. In addition, we computed ethanol dehydration, which generates ethylene, one of the major undesired side reaction products for butadiene formation. DFT results showed that ZnO favored dehydrogenation over dehydration, while MgO favored dehydration.

DFT Study of GaN Clusters Decorated with Rh and Pt Nanoparticles for the Photochemical Reduction of CO2

“…Investigations based on a cluster model approach can be advantageous over periodic boundary condition (PBC) methods because they enable the use of hybrid functionals at a lower computational cost, and, therefore, a highly accurate description of electronic properties. Moreover, cluster approaches are more appropriate for studying charged systems, thanks to the ability to add/subtract a charge carrier without suffering from interactions with similar charge carriers due to periodic boundary conditions. , Due to their reduced size, cluster approaches can be used to investigate complex reaction mechanisms, allowing for the interception of all the involved stationary points, including the more complex transition states. − However, PBC calculations allow for modeling more extended surfaces and provide an accurate description of the structural properties of the surface and molecular adsorbates. The complementarity of the two computational methods can therefore lead to an in-depth understanding of the structure–property relationship …”

Gallium Nitride‐based Materials as Promising Catalysts for CO2 Reduction: A DFT Study on the Effect of CO2 Coverage and the Incorporation of Mg Doping or Substitutional In

“…[34][35][36][37][38][39][40][41][42] Motivated by these promising results, in a preliminary work, [24] we have investigated the photocatalytic activity of the undoped GaN and GaN doped with one single Mg atom, along with the CO 2 reduction to methanol. The DFT investigation was carried out using a cluster model approach, that has some advantages over periodic boundary condition (PBC) calculations such us the utilization of hybrid functionals, [43][44][45] and the investigation of complex reaction mechanism, [46,47] at lower computational cost than periodic boundary condition (PBC) calculations. However, cluster model approaches do not allow for the investigation of extended surfaces and heterojunctions, which can be more conveniently performed by means of PBC calculations.…”

d-Glucose Adsorption on the TiO2 Anatase (100) Surface: A Direct Comparison Between Cluster-Based and Periodic Approaches

“…The ability to add/subtract a charge carrier without suffering from interactions with similar charge carriers due to PBC ( Butera and Caspary Toroker, 2016 ) makes CAs suitable for the study of charged systems. Thanks to the reduced size, the CA can be used to intercept all the stationary points, including the more complex transition states, involved in the catalytic cycle, and to determine the rate-determining states ( D’Arienzo et al, 2017 ; Butera et al, 2018 ; Butera et al, 2021 ). However, the selection of the cluster models is not trivial.…”