Amination of 1-hexanol on bimetallic AuPd/TiO<sub>2</sub>catalysts

Ball, Madelyn R.; Wesley, Thejas S.; Rivera-Dones, Keishla R.; Huber, George W.; Dumesic, James A.

doi:10.1039/c8gc02321b

Cited by 22 publications

(19 citation statements)

References 95 publications

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“…Catalyst Synthesis: A series of CeO x -Pd/C catalysts were synthesized by selective deposition of CeO x onto carbon-supported Pd nanoparticles by controlled surface reactions (CSR). [57][58][59][60][61][70][71][72][73][74][75][76][77] First, a 10 wt% Pd/C catalyst was prepared by wet impregnation by adding a solution of 0.84 g of palladium (II) acetate in 100 mL of dichloromethane to 3.6 g of Vulcan XC-72 carbon. The mixture was stirred in an open vessel at 323 K to evaporate the solvent.…”

Section: Methodsmentioning

confidence: 99%

Synthesis of CeO_x‐Decorated Pd/C Catalysts by Controlled Surface Reactions for Hydrogen Oxidation in Anion Exchange Membrane Fuel Cells

Singh

Davydova

Douglin

et al. 2020

Adv Funct Materials

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Due to the sluggish kinetics of the hydrogen oxidation reaction (HOR) in alkaline electrolytes, the development of more efficient HOR catalysts is essential for the next generation of anion‐exchange membrane fuel cells (AEMFCs). In this work, CeOx is selectively deposited onto carbon‐supported Pd nanoparticles by controlled surface reactions, aiming to enhance the homogenous distribution of CeOx and its preferential attachment to Pd nanoparticles, to achieve highly active CeOx‐Pd/C catalysts. The catalysts are characterized by inductively coupled plasma–atomic emission spectroscopy, X‐ray diffraction, high‐resolution transmission electron microscopy, scanning transmission electron microscopy (STEM), electron energy loss spectroscopy, and X‐ray photoelectron spectroscopy to confirm the bulk composition, phases present, morphology, elemental mapping, local oxidation, and surface chemical states, respectively. The intimate contact between Pd and CeOx is shown through high‐resolution STEM maps. The oxophilic nature of CeOx and its effect on Pd are probed by CO stripping. The interfacial contact area between CeOx and Pd nanoparticles is calculated for the first time and correlated to the electrochemical performance of the CeOx‐Pd/C catalysts. Highest recorded HOR specific exchange current (51.5 mA mg−1Pd) and H2–O2 AEMFC performance (peak power density of 1,169 mW cm−2 mgPd−1) are obtained with a CeOx‐Pd/C catalyst with Ce0.38/Pd bulk atomic ratio.

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Section: Methodsmentioning

confidence: 99%

Synthesis of CeO_x‐Decorated Pd/C Catalysts by Controlled Surface Reactions for Hydrogen Oxidation in Anion Exchange Membrane Fuel Cells

Singh

Davydova

Douglin

et al. 2020

Adv Funct Materials

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“…PdAu alloys can provide catalytic rates and selectivities that exceed those of monometallic Pd or Au catalysts; however, ascertaining the reasons for these differences remains a challenge. The formation of PdAu alloys modifies both the electronic and geometric structure of Pd, which has been demonstrated by investigations that involve X-ray photoelectron spectroscopy (XPS), − X-ray absorption spectroscopy (XAS), ,− and Fourier transform infrared spectroscopy (FTIR) of adsorbed CO. ,,,,,,,− These two effects are entangled and complicate the interpretation of data obtained by these methods, because the atomic composition and arrangement of PdAu alloy surfaces affect the electronic structure. Pd and Au are miscible and form a substitutional, exothermic alloy (−2 > Δ H mix > −9 kJ mol –1 ) for all compositions. − As such, Monte Carlo simulations of PdAu surfaces predict the formation of significant numbers of isolated Pd monomers when the mole fraction of Au greatly exceeds that of Pd. − Most results indicate that Pd atoms gain d-electrons as the Au contents in PdAu alloys increase.…”

Section: Introductionmentioning

confidence: 99%

Effect of Pd Coordination and Isolation on the Catalytic Reduction of O₂ to H₂O₂ over PdAu Bimetallic Nanoparticles

et al. 2021

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The direct synthesis of hydrogen peroxide (H2 + O2 → H2O2) may enable low-cost H2O2 production and reduce environmental impacts of chemical oxidations. Here, we synthesize a series of Pd1Au x nanoparticles (where 0 ≤ x ≤ 220, ∼10 nm) and show that, in pure water solvent, H2O2 selectivity increases with the Au to Pd ratio and approaches 100% for Pd1Au220. Analysis of in situ XAS and ex situ FTIR of adsorbed 12CO and 13CO show that materials with Au to Pd ratios of ∼40 and greater expose only monomeric Pd species during catalysis and that the average distance between Pd monomers increases with further dilution. Ab initio quantum chemical simulations and experimental rate measurements indicate that both H2O2 and H2O form by reduction of a common OOH* intermediate by proton–electron transfer steps mediated by water molecules over Pd and Pd1Au x nanoparticles. Measured apparent activation enthalpies and calculated activation barriers for H2O2 and H2O formation both increase as Pd is diluted by Au, even beyond the complete loss of Pd–Pd coordination. These effects impact H2O formation more significantly, indicating preferential destabilization of transition states that cleave O–O bonds reflected by increasing H2O2 selectivities (19% on Pd; 95% on PdAu220) but with only a 3-fold reduction in H2O2 formation rates. The data imply that the transition states for H2O2 and H2O formation pathways differ in their coordination to the metal surface, and such differences in site requirements require that we consider second coordination shells during the design of bimetallic catalysts.

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“…Aniline has been produced from phenol in approximately 50 % yield of over Pd−Au/Al 2 O 3 . The Dumesic group used the same metal combination to activate n‐hexanol toward amine products (primary, secondary, tertiary) using a Pd−Au catalyst that showed improved turnover frequencies compared to either pure metal . To the best of our knowledge, all of these examples proceed through the hydrogen‐borrowing strategy.…”

Section: Introductionmentioning

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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Amination of 1-hexanol on bimetallic AuPd/TiO₂catalysts

Abstract: AuPd/TiO2 bimetallic catalysts, synthesized using controlled surface reactions, exhibit enhanced rates for amination of hexanol using ammonia compared to monometallic Au and Pd catalysts.

Cited by 22 publications

References 95 publications

Synthesis of CeO_x‐Decorated Pd/C Catalysts by Controlled Surface Reactions for Hydrogen Oxidation in Anion Exchange Membrane Fuel Cells

Synthesis of CeO_x‐Decorated Pd/C Catalysts by Controlled Surface Reactions for Hydrogen Oxidation in Anion Exchange Membrane Fuel Cells

Effect of Pd Coordination and Isolation on the Catalytic Reduction of O₂ to H₂O₂ over PdAu Bimetallic Nanoparticles

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

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Amination of 1-hexanol on bimetallic AuPd/TiO2catalysts

Abstract: AuPd/TiO2 bimetallic catalysts, synthesized using controlled surface reactions, exhibit enhanced rates for amination of hexanol using ammonia compared to monometallic Au and Pd catalysts.

Cited by 22 publications

References 95 publications

Synthesis of CeOx‐Decorated Pd/C Catalysts by Controlled Surface Reactions for Hydrogen Oxidation in Anion Exchange Membrane Fuel Cells

Synthesis of CeOx‐Decorated Pd/C Catalysts by Controlled Surface Reactions for Hydrogen Oxidation in Anion Exchange Membrane Fuel Cells

Effect of Pd Coordination and Isolation on the Catalytic Reduction of O2 to H2O2 over PdAu Bimetallic Nanoparticles

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

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Amination of 1-hexanol on bimetallic AuPd/TiO₂catalysts

Synthesis of CeO_x‐Decorated Pd/C Catalysts by Controlled Surface Reactions for Hydrogen Oxidation in Anion Exchange Membrane Fuel Cells

Synthesis of CeO_x‐Decorated Pd/C Catalysts by Controlled Surface Reactions for Hydrogen Oxidation in Anion Exchange Membrane Fuel Cells

Effect of Pd Coordination and Isolation on the Catalytic Reduction of O₂ to H₂O₂ over PdAu Bimetallic Nanoparticles