Direct <i>n</i>-octanol amination by ammonia on supported Ni and Pd catalysts: activity is enhanced by “spectator” ammonia adsorbates

Dumon, Alexandre S.; Wang, Tao; Ibáñez, Javier; Tomer, A.; Yan, Zaoxue; Wischert, Raphaël; Sautet, Philippe; Pera‐Titus, Marc; Michel, Carine

doi:10.1039/c7cy02208e

Cited by 30 publications

(22 citation statements)

References 77 publications

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“…NH 3 has been proposed to aid in alcohol dehydrogenation over the Ni(111) surface. 28 However, the rate over Ni/HAP does not vary with NH 3 partial pressure. Thus, an NH 3 -mediated pathway may not be relevant for supported Ni catalysts.…”

Section: ■ Results and Discussionmentioning

confidence: 96%

Propanol Amination over Supported Nickel Catalysts: Reaction Mechanism and Role of the Support

Defalque

Zheng

et al. 2019

ACS Catal.

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Ni-supported hydroxyapatite catalyst (Ni/ HAP) was characterized and evaluated for propanol amination to propylamine at 423 K. The reaction proceeds via dehydroamination, a process that involves sequential dehydrogenation, condensation, and hydrogenation. Kinetic and isotopic studies indicate that α-H abstraction from propoxide species limits the rate of the dehydrogenation step and hence the overall rate of reaction. The rate of propanol dehydrogenation depends on the composition of the support and on the concentration of Ni sites located at the interface between Ni nanoparticles and the support. Ni/HAP is an order of magnitude more active than Ni/SiO 2 and displays a higher selectivity toward the primary amine. The superior performance of Ni/HAP is attributed to the high density of basic sites on HAP, which are responsible for stabilizing alkoxide intermediates and suppressing the disproportionation and secondary amination of amines.

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Section: ■ Results and Discussionmentioning

confidence: 96%

Propanol Amination over Supported Nickel Catalysts: Reaction Mechanism and Role of the Support

Defalque

Zheng

et al. 2019

ACS Catal.

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“…The possibility that ammonia can selectively poison sites responsible for coupling reactions has been speculated in the past . Co‐adsorbed ammonia is found to significantly impact the reactivity of methanol amination over Pd(111) and Ni(111) via density functional theory (DFT) calculations . However, it is experimentally challenging to deconvolute two potential effects of ammonia: the ammonia concentration certainly shifts the equilibrium towards the preferred products via Le Châtelier's principle, but ammonia may also inhibit hydrogenation via competitive adsorption.…”

Section: Resultsmentioning

confidence: 99%

Selectivity Control in Catalytic Reductive Amination of Furfural to Furfurylamine on Supported Catalysts

et al. 2020

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Amines are widely used in the manufacture of pharmaceuticals, agricultural chemicals, polymers, and surfactants. However, amines are mostly produced via petrochemical means, which motivates amine production from renewable resources, such as biomass. However, biomass compounds present added challenges involving poor carbon balances. We show that furfural reacts homogeneously with ammonia to produce reactive primary imines, which form large side products and leads to significant carbon losses. The carbon balance is improved by mixing furfural with furfurylamine prior to reaction to form a secondary imine for use as the reaction substrate. While controlling the primary to secondary amine selectivity is a common challenge in reductive amination, supported metal catalysts, including Ni/SiO2, Co/SiO2, and Ru/SiO2 optimize the primary amine yield to 90 to 94 % by using the secondary imine as the reaction substrate. A qualitative correlation between the primary to secondary amine selectivity with the nitrogen binding energy of metals is identified.

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“…At a typical NH 3 pressure for amination experiments (67.5 kPa), the surface was found to be not bare, but partially covered by NH 3 (coverage of 1/9 ML), and the inclusion of chemisorbed NH 3 was required to properly assess the relative activity of Pd and Ni catalysts. 34 In light of this observation, co-adsorbed NH 3 was hence considered in the remainder of this study for all possible pathways under the general H 2 -borrowing mechanism.…”

Section: Resultsmentioning

confidence: 99%

Rational design of selective metal catalysts for alcohol amination with ammonia

et al. 2019

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The lack of selectivity for the direct amination of alcohols with ammonia, a modern and clean route for the synthesis of primary amines, is an unsolved challenge. Here, we combine first-principles calculations, scaling relations, kinetic simulations and catalysis experiments to unveil the key factors governing the activity and selectivity of metal catalysts for this reaction. We show that the loss of selectivity towards primary amines is linked to a surface-mediated C-N bond coupling between two N-containing intermediates: CH 3 NH and CH 2 NH. The barrier for this step is low enough to compete with the main surface hydrogenation reactions and can be used as a descriptor for selectivity. The combination of activity and selectivity maps using the C and O adsorption energies as descriptors is used for the computational screening of 348 dilute bimetallic catalysts. Among the best theoretical candidates, Co 98.5 Ag 1.5 and Co 98.5 Ru 1.5 (5 wt% Co) are identified as the most promising catalysts from experiments.

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Direct n-octanol amination by ammonia on supported Ni and Pd catalysts: activity is enhanced by “spectator” ammonia adsorbates

Abstract: DFT calculations highlight the role of co-adsorbed ammonia in catalytic activity in the amination of alcohols by ammonia.

Cited by 30 publications

References 77 publications

Propanol Amination over Supported Nickel Catalysts: Reaction Mechanism and Role of the Support

Propanol Amination over Supported Nickel Catalysts: Reaction Mechanism and Role of the Support

Selectivity Control in Catalytic Reductive Amination of Furfural to Furfurylamine on Supported Catalysts

Rational design of selective metal catalysts for alcohol amination with ammonia

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