Selective Oxidative Dehydrogenation of Ethane and Propane over Copper‐Containing Mordenite: Insights into Reaction Mechanism and Product Protection

Artsiusheuski, Mikalai A.; Verel, René; van Bokhoven, Jeroen A.; Sushkevich, Vitaly L.

doi:10.1002/anie.202309180

Cited by 7 publications

(5 citation statements)

References 74 publications

(193 reference statements)

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“…Alongside each structure, the δ( 13 C) chemical shifts (ppm) are noted for particular C atoms in blue, while ν CC frequencies (cm –1 ) are noted in red. The data are taken from literature references. ,− ,,,− …”

Section: Mechanisms Of Alkene Oligomerizationmentioning

confidence: 99%

Mechanisms of Light Alkene Oligomerization on Metal-Modified Zeolites

Lashchinskaya,

Gabrienko,

Stepanov

2024

ACS Catal.

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Zeolites modified with metal (Zn, Ga, Ni, etc.) species of various nature and composition perform oligomerization of light alkenes with high conversion and selectivity to dimeric products. Despite the significant difference in catalytic properties of metal-modified zeolites compared to unmodified H-form zeolite performance, the ability of metal-containing sites to catalyze alkene oligomerization has been debated, with the key role attributed to zeolite Brønsted acid sites (BAS). However, recent spectroscopic and theoretical investigations provide evidence for metal species involvement in alkene transformations. In this Review, we have outlined the features of BAS-assisted alkene oligomerization and further discussed the characteristics of oligomerization assisted by metal-containing sites. The possible mechanisms of metal-assisted hydrocarbon chain elongation have been categorized into several types depending on the nature of the key intermediate: alkyl-based, vinyl-based, allyl-based, and metallacycle. The emphasis has been placed on spectroscopic ( 13 C MAS NMR and FTIR) characteristics of these intermediates, both experimentally available and also hypothetically expected, that serve as the indicators of the reaction occurrence with the assistance of BAS and metal sites. The remaining problems and challenges concerning the detection and identification of the reaction intermediates of light alkene oligomerization on zeolite catalysts and possible strategies to solve them in future studies are also outlined.

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Section: Mechanisms Of Alkene Oligomerizationmentioning

confidence: 99%

Mechanisms of Light Alkene Oligomerization on Metal-Modified Zeolites

Lashchinskaya,

Gabrienko,

Stepanov

2024

ACS Catal.

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“…Propylene is a key raw material for the production of a wide range of chemical products and is traditionally obtained from steam cracking and fluidized catalytic cracking. , However, hydraulic fracturing, especially in North America, has led to large-scale extraction of shale gases, making light alkanes such as propane increasingly economical. This shift has significantly highlighted propane dehydrogenation (PDH) technologies in the industry.…”

Section: Introductionmentioning

confidence: 99%

Identifying the Active Phase on Atomically Dispersed Catalysts for Propane Dehydrogenation: Positively Charged vs Metallic Transition Metals

Hu,

Lei,

Sui

et al. 2024

ACS Catal.

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Atomically dispersed transition-metal catalysts have received increasing research interest in heterogeneous catalysis. However, the nature of the real active phase, specifically how the oxidation state of active species may affect the catalytic performance, remains elusive. In this work, ab initio molecular dynamics and large-scale molecular dynamics simulations based on neural network potentials have been employed to assess the structural stability of 52 single-and dual-atom catalysts with transition metals including Mn−Cu, Ru−Ag, and Os−Au embedded in the metal or oxygen vacancies on the defective TiO 2 surface. On the thermodynamically stable surfaces, microkinetic analysis combined with results from DFT calculations indicates the metal atoms stabilized in the Ti vacancies with a positive oxidation state generally promote propane dehydrogenation (PDH) with the assistance of adjacent O sites, whereas those in the O vacancies exhibiting metallic properties act as a sole active site for C−H bond activation. The scaling relations established show that the adsorption energies of H and H&H can be used as two simple but effective PDH activity descriptors across both positively charged and metallic metal-doped surfaces. The calculated TOF under the realistic experimental conditions reaches a maximum at a slightly negative oxidation state, implying the Pt and Ir in the metallic state would dominate the kinetics of PDH. Moreover, a high selectivity toward propylene may be attained because the scaling relation between the activation energies for the C−H bond breaking in propane and propylene is broken in the absence of multiple metallic metal−metal sites on the atomically dispersed catalysts. An understanding of this structure−activity relationship is of vital importance for the rational design and optimization of heterogeneous catalysts for light alkane dehydrogenation.

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“…Cu K-edge X-ray absorption spectroscopy is an ideal technique to probe the composition of the Cu cocatalyst. − The elemental specificity of X-ray absorption allows for selective probing of Cu in the multicomponent p-GaN/Al 2 O 3 /Au/Cu system. The X-ray absorption near-edge structure (XANES) region of the Cu K-edge absorption spectrum is highly sensitive to both the oxidation state and coordination environment of Cu. , The method can also be applied under operating conditions, for example, under CO 2 and H 2 O vapor atmosphere and under visible light illumination, which is relevant here when characterizing the Cu cocatalyst composition in p-GaN/Al 2 O 3 /Au/Cu.…”

Section: Introductionmentioning

confidence: 99%

“…The X-ray absorption near-edge structure (XANES) region of the Cu K-edge absorption spectrum is highly sensitive to both the oxidation state and coordination environment of Cu. , The method can also be applied under operating conditions, for example, under CO 2 and H 2 O vapor atmosphere and under visible light illumination, which is relevant here when characterizing the Cu cocatalyst composition in p-GaN/Al 2 O 3 /Au/Cu. It has previously been employed to resolve changes in Cu catalyst composition under electrochemical , and photochemical ,, conditions.…”

Section: Introductionmentioning

confidence: 99%

“… 39 , 43 The method can also be applied under operating conditions, 44 for example, under CO 2 and H 2 O vapor atmosphere and under visible light illumination, which is relevant here when characterizing the Cu cocatalyst composition in p-GaN/Al 2 O 3 /Au/Cu. It has previously been employed to resolve changes in Cu catalyst composition under electrochemical 38 , 42 and photochemical 31 , 33 , 36 conditions.…”

Section: Introductionmentioning

confidence: 99%

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Oxidizing Role of Cu Cocatalysts in Unassisted Photocatalytic CO₂ Reduction Using p-GaN/Al₂O₃/Au/Cu Heterostructures

Zoric,

Basera,

Palmer

et al. 2024

ACS Nano

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Photocatalytic CO 2 reduction to CO under unassisted (unbiased) conditions was recently demonstrated using heterostructure catalysts that combine p-type GaN with plasmonic Au nanoparticles and Cu nanoparticles as cocatalysts (p-GaN/Al 2 O 3 /Au/Cu). Here, we investigate the mechanistic role of Cu in p-GaN/Al 2 O 3 /Au/Cu under unassisted photocatalytic operating conditions using Cu K-edge X-ray absorption spectroscopy and first-principles calculations. Upon exposure to gas-phase CO 2 and H 2 O vapor reaction conditions, the composition of the Cu nanoparticles is identified as a mixture of Cu I and Cu II oxide, hydroxide, and carbonate compounds without metallic Cu. These composition changes, indicating oxidative conditions, are rationalized by bulk Pourbaix thermodynamics. Under photocatalytic operating conditions with visible light excitation of the plasmonic Au nanoparticles, further oxidation of Cu I to Cu II is observed, indicating light-driven hole transfer from Au-to-Cu. This observation is supported by the calculated band alignments of the oxidized Cu compositions with plasmonic Au particles, where light-driven hole transfer from Au-to-Cu is found to be thermodynamically favored. These findings demonstrate that under unassisted (unbiased) gas-phase reaction conditions, Cu is found in carbonate-rich oxidized compositions rather than metallic Cu. These species then act as the active cocatalyst and play an oxidative rather than a reductive role in catalysis when coupled with plasmonic Au particles for light absorption, possibly opening an additional channel for water oxidation in this system.

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Selective Oxidative Dehydrogenation of Ethane and Propane over Copper‐Containing Mordenite: Insights into Reaction Mechanism and Product Protection

Cited by 7 publications

References 74 publications

Mechanisms of Light Alkene Oligomerization on Metal-Modified Zeolites

Mechanisms of Light Alkene Oligomerization on Metal-Modified Zeolites

Identifying the Active Phase on Atomically Dispersed Catalysts for Propane Dehydrogenation: Positively Charged vs Metallic Transition Metals

Oxidizing Role of Cu Cocatalysts in Unassisted Photocatalytic CO₂ Reduction Using p-GaN/Al₂O₃/Au/Cu Heterostructures

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Selective Oxidative Dehydrogenation of Ethane and Propane over Copper‐Containing Mordenite: Insights into Reaction Mechanism and Product Protection

Cited by 7 publications

References 74 publications

Mechanisms of Light Alkene Oligomerization on Metal-Modified Zeolites

Mechanisms of Light Alkene Oligomerization on Metal-Modified Zeolites

Identifying the Active Phase on Atomically Dispersed Catalysts for Propane Dehydrogenation: Positively Charged vs Metallic Transition Metals

Oxidizing Role of Cu Cocatalysts in Unassisted Photocatalytic CO2 Reduction Using p-GaN/Al2O3/Au/Cu Heterostructures

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Oxidizing Role of Cu Cocatalysts in Unassisted Photocatalytic CO₂ Reduction Using p-GaN/Al₂O₃/Au/Cu Heterostructures