Oxidative dehydrogenation of ethanol on gold: Combination of kinetic experiments and computation approach to unravel the reaction mechanism

Behravesh, Erfan; Melander, Marko; Wärnå, Johan; Salmi, Tapio; Honkala, Karoliina; Murzin, Dmitry Yu.

doi:10.1016/j.jcat.2020.07.022

Cited by 32 publications

(24 citation statements)

References 69 publications

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“…The mechanism and kinetics of oxidative dehydrogenation of ethanol over gold catalysts was recently reported [47]. DFT calculations indicated that the activation of molecular oxygen is facilitated in the presence of ethanol acting as a hydrogen donor.…”

Section: Oxidative Dehydrogenation Of Ethanol: a Multi-route Mechanism With Nonlinear Stepsmentioning

confidence: 97%

“…According to the DFT calculations [47] illustrated in Figure 3, the largest activation barrier corresponds to step 3 in Equation (20), and thus superficially it can be considered in the conventional approaches as the rate limiting step. However, the activation energy of the same step in the reverse direction is very low and step 3 can even be viewed to be close to the quasi-equilibrium.…”

Section: Oxidative Dehydrogenation Of Ethanol: a Multi-route Mechanism With Nonlinear Stepsmentioning

confidence: 99%

“…This approach is possible because of the specific features of the reaction mechanism comprising only nonlinear steps and thus allowing derivation of an analytic rate expression. Such derivation was done in [47] based on the DFT computed reaction energies assuming quasi-equilibria for steps 1 and 2, irreversibility for steps 4 and 5 and reversibility for steps 3 and 6.…”

Section: Oxidative Dehydrogenation Of Ethanol: a Multi-route Mechanism With Nonlinear Stepsmentioning

confidence: 99%

“…Derivation of the rate expression (per mole of oxygen) for the route N (1b) was described in [47], giving ( )…”

Section: Oxidative Dehydrogenation Of Ethanol: a Multi-route Mechanism With Nonlinear Stepsmentioning

confidence: 99%

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Requiem for the Rate-Determining Step in Complex Heterogeneous Catalytic Reactions?

Murzin

2020

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The concept of the rate determining step, i.e., the step having the strongest influence on the reaction rate or even being the only one present in the rate equation, is often used in heterogeneous catalytic reactions. The utilization of this concept mainly stems from a need to reduce complexity in deriving explicit rate equations or searching for a better catalyst based on the theoretical insight. When the aim is to derive a rate equation with eventual kinetic modelling for single-route mechanisms with linear sequences, the analytical rate expressions can be obtained based on the theory of complex reactions. For such mechanisms, a single rate limiting step might not be present at all and the common practice of introducing such steps is due mainly to the convenience of using simpler expressions. For mechanisms with a combination of linear and nonlinear steps or those just comprising non-linear steps, the reaction rates are influenced by several steps depending on reaction conditions, thus a reduction in complexity to a single rate limiting step can lead to misinterpretations. More widespread utilization of a microkinetic approach when the reaction rate constants can be computed with reasonable accuracy based on the theoretical insight, and availability of software for kinetic modelling, when a system of differential equations for reactants and products will be solved together with differential equations for catalytic species and the algebraic conservation equation for the latter, will eventually make the concept of the rate limiting step obsolete.

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Section: Oxidative Dehydrogenation Of Ethanol: a Multi-route Mechanism With Nonlinear Stepsmentioning

confidence: 97%

Section: Oxidative Dehydrogenation Of Ethanol: a Multi-route Mechanism With Nonlinear Stepsmentioning

confidence: 99%

Section: Oxidative Dehydrogenation Of Ethanol: a Multi-route Mechanism With Nonlinear Stepsmentioning

confidence: 99%

“…Derivation of the rate expression (per mole of oxygen) for the route N (1b) was described in [47], giving ( )…”

Section: Oxidative Dehydrogenation Of Ethanol: a Multi-route Mechanism With Nonlinear Stepsmentioning

confidence: 99%

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Requiem for the Rate-Determining Step in Complex Heterogeneous Catalytic Reactions?

Murzin

2020

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“…The Kohn-Sham equations were solved using a real-space grid method with a grid spacing of 0.18 Å, which has been demonstrated to yield converged energies for alcohols and oxides on Au. 60 The exchange and correlation effects were described using the PBE 61,62 functional with the Tkatchenko and Scheffler (TS09) 63 dispersion correction. The solvent was accounted for by using a continuum solvent model 64 for water as implemented in GPAW.…”

Section: Computational Detailsmentioning

confidence: 99%

On the Mechanistic Origins of the pH-Dependency in Au-Catalyzed Glycerol Electro-Oxidation: Insight from First Principles Calculations

Verma¹,

Melander

Honkala³

2021

Preprint

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We have performed a comprehensive computational study to understand and explain the experimentally observed pH- and potential-dependency of alkaline electro-oxidation of glycerol on gold. It is shown that the adsorbed OH groups have a decisive role on the reaction mechanism, thermodynamics, and kinetics. Overall, our findings highlight that computational studies should explicitly account for pH and coverage effects under alkaline conditions for electrocatalytic oxidation reactions to reliably predict electrocatalytic behaviour.

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Effect of Ni, La, and Ce Oxides on a Cu/Al₂O₃ Catalyst with Low Copper Loading for Ethanol Non‐oxidative Dehydrogenation

et al. 2021

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The effect of modifying additives (Ni, La, Ce oxides) on the activity of Cu/Al2O3 with a low copper loading was studied for ethanol non‐oxidative dehydrogenation. The catalysts were prepared by impregnation of the commercial Al2O3 granules and characterized by Brunauer‐Emmett‐Teller (BET), scanning electron microscopy (SEM), temperature‐programmed desorption of NH3 (TPD‐NH3), temperature‐programmed reduction of H2 (H2‐TPR), and thermogravimetric analysis (TGA). Modification of Cu/Al2O3 with Ni, La, and Ce oxides results in increasing catalytic activity. A modification of the Cu/Al2O3 catalyst with nickel and lanthanum oxides, in contrast to cerium oxide, leads to an improvement in the dispersion of the catalyst particles. The Cu‐Ni/Al2O3 catalyst with the highest acidity has the highest selectivity for acetaldehyde. The highest selectivity for butanol is observed for the Cu‐La/Al2O3 catalyst, which has the lowest acidity.

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Oxidative dehydrogenation of ethanol on gold: Combination of kinetic experiments and computation approach to unravel the reaction mechanism

Cited by 32 publications

References 69 publications

Requiem for the Rate-Determining Step in Complex Heterogeneous Catalytic Reactions?

Requiem for the Rate-Determining Step in Complex Heterogeneous Catalytic Reactions?

On the Mechanistic Origins of the pH-Dependency in Au-Catalyzed Glycerol Electro-Oxidation: Insight from First Principles Calculations

Effect of Ni, La, and Ce Oxides on a Cu/Al₂O₃ Catalyst with Low Copper Loading for Ethanol Non‐oxidative Dehydrogenation

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Oxidative dehydrogenation of ethanol on gold: Combination of kinetic experiments and computation approach to unravel the reaction mechanism

Cited by 32 publications

References 69 publications

Requiem for the Rate-Determining Step in Complex Heterogeneous Catalytic Reactions?

Requiem for the Rate-Determining Step in Complex Heterogeneous Catalytic Reactions?

On the Mechanistic Origins of the pH-Dependency in Au-Catalyzed Glycerol Electro-Oxidation: Insight from First Principles Calculations

Effect of Ni, La, and Ce Oxides on a Cu/Al2O3 Catalyst with Low Copper Loading for Ethanol Non‐oxidative Dehydrogenation

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Effect of Ni, La, and Ce Oxides on a Cu/Al₂O₃ Catalyst with Low Copper Loading for Ethanol Non‐oxidative Dehydrogenation