Stability and reactivity of copper oxo-clusters in ZSM-5 zeolite for selective methane oxidation to methanol

Li, G Guanna; Vassilev, PD Peter; Sanchez‐Sanchez, Maricruz; Lercher, Johannes A.; Hensen, Emiel Emiel; Pidko, Evgeny A.

doi:10.1016/j.jcat.2016.03.014

Cited by 225 publications

(288 citation statements)

References 78 publications

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“…[6] These enzymes,containing Cu or Fe metal centers,have inspired the design of materials for the conversion of CH 4 to CH 3 OH under mild reaction conditions. [9][10][11][12][13] Thes tructure of the active site is highly debated, with evidence for both (m-oxo) dinuclear copper [9,14] and tris(moxo) trinuclear copper centers (Figure 1a). This hurdle can, in principle,b eo vercome using the concept of chemical looping,w hich entails decoupling the steps of oxidation of Cu sites and their reaction with CH 4 .…”

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“…[7] Attempts to perform this reaction catalytically with tailored materials have mostly been unsuccessful because the selectivity toward CH 3 OH is low at high CH 4 conversion. [9][10][11][12][13] Thes tructure of the active site is highly debated, with evidence for both (m-oxo) dinuclear copper [9,14] and tris(moxo) trinuclear copper centers ( Figure 1a). [8] Thel ast step of the cycle utilizes aprotic solvent to desorb the CH 3 Ospecies that are strongly bound to the copper sites.O ft he various systems that have been investigated, Cu-exchanged zeolites have shown potential for the selective oxidation of CH 4 to CH 3 OH using molecular oxygen as an oxidant.…”

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Monomeric Copper(II) Sites Supported on Alumina Selectively Convert Methane to Methanol

et al. 2019

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Monomeric Cu II sites supported on alumina, prepared using surface organometallic chemistry,c onvert CH 4 to CH 3 OH selectively.T his reaction takes place by formation of CH 3 Os urface species with the concomitant reduction of two monomeric Cu II sites to Cu I ,a ccording to mass balance analysis,i nfrared, solid-state nuclear magnetic resonance,X -ray absorption, and electron paramagnetic resonance spectroscopys tudies.T his material contains as ignificant fraction of Cu active sites (22 %) and displays as electivity for CH 3 OH exceeding 83 %, based on the number of electrons involved in the transformation. These alumina-supported Cu II sites reveal that C À Hbond activation, along with the formation of CH 3 O-surface species,c an occur on pairs of proximal monomeric Cu II sites in as hort reaction time.The main constituent of natural gas,C H 4 ,i si ncreasingly produced by fracking and is widely available at extraction sites for fossil fuels.T ransport of CH 4 as liquefied natural gas is,however,expensive and energy intensive;hence,itisoften flared despite the consequent highly negative environmental impacts and loss of resource.F inding efficient routes to convert CH 4 to liquid fuels or chemicals on-site is,therefore, of significant economic and environmental importance.A s such, direct conversion of CH 4 to CH 3 OH is noteworthy since it provides al iquid that can be directly used as ac hemical feedstock, fuel, or fuel additive.H owever,t his process remains ag rand challenge because over-oxidation is favored by the higher reactivity of CH 3 OH compared to CH 4 . [1][2][3][4][5] In nature,bacterial enzymes such as methane monooxygenases, are able to oxidize CH 4 to CH 3 OH with high selectivity using O 2 as the primary oxidant. [6] These enzymes,containing Cu or Fe metal centers,have inspired the design of materials for the conversion of CH 4 to CH 3 OH under mild reaction conditions. [7] Attempts to perform this reaction catalytically with tailored materials have mostly been unsuccessful because the selectivity toward CH 3 OH is low at high CH 4 conversion. This hurdle can, in principle,b eo vercome using the concept of chemical looping,w hich entails decoupling the steps of oxidation of Cu sites and their reaction with CH 4 . [8] Thel ast step of the cycle utilizes aprotic solvent to desorb the CH 3 Ospecies that are strongly bound to the copper sites.O ft he various systems that have been investigated, Cu-exchanged zeolites have shown potential for the selective oxidation of CH 4 to CH 3 OH using molecular oxygen as an oxidant. [9][10][11][12][13] Thes tructure of the active site is highly debated, with evidence for both (m-oxo) dinuclear copper [9,14] and tris(moxo) trinuclear copper centers (Figure 1a). [15] Recent theoretical studies also suggest that monomeric Cu sites should not be excluded. [16,17] Amajor challenge in these systems is associated with the presence of as mall fraction of active sites (often below 30-60 %; note that as ystem with 90 %a ctive-site-0.47 mol CH 3 OH/mol Cu-was recently...

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Monomeric Copper(II) Sites Supported on Alumina Selectively Convert Methane to Methanol

et al. 2019

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“…Diese Befunde wurden in einer anderen Studie reproduziert, die die Wirkung des Si/Al-Verhältnisses auf die Methanolausbeute hervorhob. [176,177] Va nelderen et al identifizierten zwei verschiedene [Cu-O-Cu] 2+ -Stellen, die fürdie Methanoxidation in Cu-MOR aktiv sind. [169] Die unzureichende Energierückgewinnung in dieser exothermen Oxidation und die ineffiziente Isolierung von Methanol aus der verdünnten, wässrigen Reaktionsmischung verhinderten eine weitere kommerzielle Anwendung.…”

Section: Methanoxidation Mit Eisen-haltigen Zeolithenunclassified

Die direkte katalytische Oxidation von Methan zu Methanol – eine kritische Beurteilung

2017

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Es gibt vielzählige direkte, selektive Ansätze, um Methan partiell zu oxidieren, jedoch ist noch keiner von ihnen zur industriellen Reife gelangt. In diesem Zusammenhang ist die Oxidation von Methan zu Methanol eine schwierige, aber lohnende Aufgabe, da sie eine wirkungsvolle Methode ist, um das Abfackeln von Erdgas, das als Nebenprodukt in der Erdölindustrie anfällt, zu unterbinden, und zugleich die Möglichkeit bietet, Methan zu valorisieren. Dieser Aufsatz berücksichtigt die Synthese von Methanol und seinen Derivaten ausgehend von Methan durch homogen‐ und heterogenkatalytische Methoden. Er zeigt die starken Einschränkungen der direkten katalytischen Synthese von Methanol aus Methan auf und unterstreicht dabei die enorme Überlegenheit von Systemen, die Methanolderivate produzieren oder sich durch Besonderheiten wie die Verwendung von Mehrkomponenten‐Katalysatoren zur Methanolstabilisierung auszeichnen. Für die zukünftige Forschung erweist sich die Stabilisierung von Methanol in der homogenen und heterogenen Katalyse als unentbehrlich.

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“…The concept of concentration‐dependent free energies is the basis of the ab initio thermodynamic (aiTD) analysis technique originally introduced by Reuter et al . This method is currently widely used in computational heterogeneous catalysis for the operando modeling of the composition of the reactive surfaces and microporous spaces . Since recently the applicability of this approach has been extended towards analyzing the dynamics of the surface sites under the catalytic conditions .…”

Section: Introductionmentioning

confidence: 99%

Operando Modeling of Multicomponent Reactive Solutions in Homogeneous Catalysis: from Non‐standard Free Energies to Reaction Network Control

Kuliaev

Pidko

2019

ChemCatChem

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Dedicated to the memory of Prof. Georgy M. Zhidomirov.Optimization and execution of chemical reactions are to a large extend based on experience and chemical intuition of a chemist. The chemical intuition is rooted in the phenomenological Le Chatelier's principle that teaches us how to shift equilibrium by manipulating the reaction conditions. To access the underlying thermodynamic parameters and their conditiondependencies from the first principles is a challenge. Here, we present a theoretical approach to model non-standard free energies for a complex catalytic CO 2 hydrogenation system under operando conditions and identify the condition spaces where catalyst deactivation can potentially be suppressed. Investigation of the non-standard reaction free energy dependencies allows rationalizing the experimentally observed activity patterns and provides a practical approach to optimization of the reaction paths in complex multicomponent reactive catalytic systems.

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Stability and reactivity of copper oxo-clusters in ZSM-5 zeolite for selective methane oxidation to methanol

Cited by 225 publications

References 78 publications

Monomeric Copper(II) Sites Supported on Alumina Selectively Convert Methane to Methanol

Monomeric Copper(II) Sites Supported on Alumina Selectively Convert Methane to Methanol

Die direkte katalytische Oxidation von Methan zu Methanol – eine kritische Beurteilung

Operando Modeling of Multicomponent Reactive Solutions in Homogeneous Catalysis: from Non‐standard Free Energies to Reaction Network Control

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