Heterogeneous alkane dehydrogenation catalysts investigated <i>via</i> a surface organometallic chemistry approach

Docherty, Scott R.; Rochlitz, Lukas; Payard, Pierre‐Adrien; Copéret, Christophe

doi:10.1039/d0cs01424a

Cited by 75 publications

(93 citation statements)

References 120 publications

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“…The search for alternative PDH catalysts, tackling these stability and selectivity issues has thus been an important field of research. [1,5] Ga 2 O 3 is one metal oxide that has received significant interest due to its promising initial activity and selectivity in alkane dehydrogenation. However, this system undergoes rapid deactivation likely due to the reduction of Ga 2 O 3 .…”

Section: Introductionmentioning

confidence: 99%

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A Molecular Analogue of the C−H Activation Intermediate of the Silica‐Supported Ga(III) Single‐Site Propane Dehydrogenation Catalyst: Structure and XANES Signature

Rochlitz

Searles

Nater

et al. 2021

Helvetica Chimica Acta

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Propane dehydrogenation is an important field of research due to an increasing world-wide demand of propene while classical production routes through naphtha cracking are in decline. In that context, silicasupported Ga(III) sites, synthesized from surface organometallic chemistry principles, show high selectivity and stability in the propane dehydrogenation reaction. This performance is in significant contrast to the reported fast deactivation and lower selectivity of most Ga 2 O 3 and CrO 3 based materials. The Ga-catalyzed propane dehydrogenation reaction is proposed to proceed through the formation of Ga alkyl intermediates for which it would be desirable to have detailed structural and spectroscopic information. Here, we prepare a consistent series of Ga(III) molecular complexes with varying numbers of alkyl and siloxide ligands; they are characterized by single crystal X-Ray diffraction and X-Ray Absorption Near Edge Structure analysis, which is known to be highly sensitive to the Ga coordination environment. We report in particular the structure and the spectroscopic signatures of [Ga( i Pr)(OSi(O t Bu) 3 ) 2 (HOSi(O t Bu) 3 )], a molecular mimic of the key proposed reaction intermediates in the Ga-catalyzed PDH reaction.

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Section: Introductionmentioning

confidence: 99%

“…Frequent regeneration cycles are required for these systems, decreasing the efficiency and catalyst lifetime. The search for alternative PDH catalysts, tackling these stability and selectivity issues has thus been an important field of research [1,5] …”

Section: Introductionmentioning

confidence: 99%

A Molecular Analogue of the C−H Activation Intermediate of the Silica‐Supported Ga(III) Single‐Site Propane Dehydrogenation Catalyst: Structure and XANES Signature

Rochlitz

Searles

Nater

et al. 2021

Helvetica Chimica Acta

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“…The reaction conditions therefore result in an increase in side reactions such as thermal cracking, deep dehydrogenation, coke formation and the sintering of the supported nanoparticles, limiting the average life of the catalyst [6]. To overcome the catalyst deactivation, it is therefore mandatory to employ a periodic regeneration through oxidative cycles to eliminate the coke, followed by reduction; moreover, oxygen-chlorine treatment can be carried out to partially redisperse agglomerated Pt particles [10].…”

Section: The Reactionmentioning

confidence: 99%

“…Innovative methods to produce propylene have been proposed, including the propane dehydrogenation (PDH), the methanol-olefin process and the Fischer-Tropsch olefin process [2]. The development of shale gas [5] extraction methods has generated an abundance of light alkanes, therefore making propane dehydrogenation the best candidate for replacing conventional propylene production processes [6]. Several catalysts and propane dehydrogenation processes have been developed, whose representatives are UOP Oleflex, Lummus Catofin, Linde-BASF PDH, Uhde STA and Snamprogetti-Yarsintez FBD [2].…”

Section: Introductionmentioning

confidence: 99%

Propylene Synthesis: Recent Advances in the Use of Pt-Based Catalysts for Propane Dehydrogenation Reaction

et al. 2021

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Propylene is one of the most important feedstocks in the chemical industry, as it is used in the production of widely diffused materials such as polypropylene. Conventionally, propylene is obtained by cracking petroleum-derived naphtha and is a by-product of ethylene production. To ensure adequate propylene production, an alternative is needed, and propane dehydrogenation is considered the most interesting process. In literature, the catalysts that have shown the best performance in the dehydrogenation reaction are Cr-based and Pt-based. Chromium has the non-negligible disadvantage of toxicity; on the other hand, platinum shows several advantages, such as a higher reaction rate and stability. This review article summarizes the latest published results on the use of platinum-based catalysts for the propane dehydrogenation reaction. The manuscript is based on relevant articles from the past three years and mainly focuses on how both promoters and supports may affect the catalytic activity. The published results clearly show the crucial importance of the choice of the support, as not only the use of promoters but also the use of supports with tuned acid/base properties and particular shape can suppress the formation of coke and prevent the deep dehydrogenation of propylene.

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“…This complexity is often inherited from the synthetic method, which leads to a mixture of surface species. We recently prepared a silica-supported PtGa-catalyst for PDH (PtGa/SiO 2 , Figure 1 ) 4 , 18 using surface organometallic chemistry (SOMC). 58 − 61 This synthetic approach allows for a more controlled introduction of each component (Ga and Pt) through sequential grafting and post-treatment steps.…”

Section: Introductionmentioning

confidence: 99%

Dynamics and Site Isolation: Keys to High Propane Dehydrogenation Performance of Silica-Supported PtGa Nanoparticles

Payard

Rochlitz

Searles

et al. 2021

JACS Au

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Nonoxidative dehydrogenation of light alkanes has seen a renewed interest in recent years. While PtGa systems appear among the most efficient catalyst for this reaction and are now implemented in production plants, the origin of the high catalytic performance in terms of activity, selectivity, and stability in PtGa-based catalysts is largely unknown. Here we use molecular modeling at the DFT level on three different models: (i) periodic surfaces, (ii) clusters using static calculations, and (iii) realistic size silica-supported nanoparticles (1 nm) using molecular dynamics and metadynamics. The combination of the models with experimental data (XAS, TEM) allowed the refinement of the structure of silica-supported PtGa nanoparticles synthesized via surface organometallic chemistry and provided a structure–activity relationship at the molecular level. Using this approach, the key interaction between Pt and Ga was evidenced and analyzed: the presence of Ga increases (i) the interaction between the oxide surface and the nanoparticles, which reduces sintering, (ii) the Pt site isolation, and (iii) the mobility of surface atoms which promotes the high activity, selectivity, and stability of this catalyst. Considering the complete system for modeling that includes the silica support as well as the dynamics of the PtGa nanoparticle is essential to understand the catalytic performances.

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Heterogeneous alkane dehydrogenation catalysts investigated via a surface organometallic chemistry approach

Abstract: Alkane dehydrogenation over heterogeneous catalysts has attracted renewed attention in recent years. Here, well-defined catalysts based on isolated metal sites and supported Pt-alloys prepared via SOMC are discussed and compared to classical systems.

Cited by 75 publications

References 120 publications

A Molecular Analogue of the C−H Activation Intermediate of the Silica‐Supported Ga(III) Single‐Site Propane Dehydrogenation Catalyst: Structure and XANES Signature

A Molecular Analogue of the C−H Activation Intermediate of the Silica‐Supported Ga(III) Single‐Site Propane Dehydrogenation Catalyst: Structure and XANES Signature

Propylene Synthesis: Recent Advances in the Use of Pt-Based Catalysts for Propane Dehydrogenation Reaction

Dynamics and Site Isolation: Keys to High Propane Dehydrogenation Performance of Silica-Supported PtGa Nanoparticles

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