Tracing Active Sites in Supported Ni Catalysts during Butene Oligomerization by <i>Operando</i> Spectroscopy under Pressure

Rabeah, Jabor; Radnik, Jörg; Briois, Valérie; Maschmeyer, Dietrich; Stochniol, Guido; Peitz, Stephan; Reeker, Helene; Fontaine, Camille La; Brückner, Angelika

doi:10.1021/acscatal.6b02331

Cited by 38 publications

(33 citation statements)

References 20 publications

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“…the most selective catalysts in the ODH of ethane). For comparison, the XAS spectrum corresponding to metallic Ni is also included in this figure . A decrease in the "white line" intensity is observed for both 20NiO/TiO2 and 92Ni-Nb-O samples, with respect to unselective NiO catalyst, likely due to a decrease in the average oxidation state of Ni atoms in modified catalysts [49]. More interestingly, it can be observed that the drop of the intensity is more drastic for promoted 92Ni-Nb-O than in the case of supported 20NiO/TiO2.…”

Section: Figurementioning

confidence: 81%

Oxidative dehydrogenation of ethane on diluted or promoted nickel oxide catalysts: Influence of the promoter/diluter

et al. 2021

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Ti-and Nb-containing NiO catalysts have been synthesized by two different preparation methods: i) by precipitation (Me-Ni-O oxides, Me= Nb or Ti), in order to prepare promoted NiO catalysts; and ii) by wet impregnation on TiO2 or NbOx supports, in order to prepare diluted/supported NiO catalysts. The catalysts have been also characterized and tested in the oxidative dehydrogenation of ethane. The catalytic performance of Ti-and Nb-promoted catalysts strongly depends on the composition, although in both cases the optimal one is found at similar Ti or Nb loadings (ca. 90 wt% NiO), showing similar ethylene selectivity in the ODH of ethane (ca. 90% at 10-20% ethane conversion). However, in the case of diluted catalysts, the catalytic behavior of Ti-and Nb-containing catalysts is drastically different. Then, over NiO diluted TiO2 catalyst, the highest selectivity to ethylene (ca. 90% selectivity) is achieved at NiO loading of 20 wt.%. However, over Nb2O5-diluted NiO catalyst, selectivity to ethylene was lower than 70%. A discussion on the characteristics of selective catalysts is done.In this case, the best catalysts must present a low concentration of free NiO and TiO2 or Nb2O5 phases, maximizing the Ni-O-Ti or Ni-O-Nb interaction. Interestingly, this takes place at different NiO loading depending on the preparation method and the nature of promoted/diluter. The low selectivity to ethylene achieved by NiO diluted with Nb2O5 has been related to the low interaction of NiO with the surface of Nb2O5, which hinders the elimination of unselective electrophilic O species.

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Section: Figurementioning

confidence: 81%

Oxidative dehydrogenation of ethane on diluted or promoted nickel oxide catalysts: Influence of the promoter/diluter

et al. 2021

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“…This is accompanied by stabilization of tri-and tetravalent nickel oxide species by aluminum [21], which in the presence of olefins (in the present case primarily 2-butene) are reduced to catalytically active nickel hydride species [22]. In addition, using in situ electron paramagnetic resonance (EPR) spectroscopy correlated with XANES/EXAFS, the formation of a Ni I /Ni II redox pair was detected during the dimerization of n-butenes, which are present as single sites [23,24]. For the formation of this species, a reaction cycle has been proposed, which requires the interaction of olefins with Ni II in the direct vicinity of a Brønsted acid site.…”

Section: Introductionmentioning

confidence: 84%

Influence of Remaining Acid Sites of an Amorphous Aluminosilicate on the Oligomerization of n-Butenes after Impregnation with Nickel Ions

et al. 2020

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Highly linear octene isomers can be produced from n-butene on industrial scale by using Ni-containing aluminosilicates as heterogeneous catalysts. These catalysts can be prepared by impregnating an aluminosilicate with a Ni(II) salt solution. This leads to a competition between acid-catalyzed and nickel-catalyzed reactions. In this study it is shown that some octene isomers are exclusively formed via an acid-catalyzed mechanism as a result of methyl group migration at the surface of a mesoporous catalyst. Specifically, the isomers 4,4-dimethylhexene (4,4-DMH) and 3-ethyl-2-methylpentene (3E-2MP) exhibit a systematic correlation compared to the amount of 3,4-dimethylhexene (3,4-DMH) formed at acid sites. By analyzing the ratio of 4,4-DMH and/or 3E-2MP to 3,4-DMH in the product spectrum before and after impregnation with a nickel precursor, the extend of acid site covered by nickel ions can be evaluated.

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“…The main products of this step are butenes. This mechanism proceeds via the oxidative coupling of ethene [53,54]. However, ethene could be further oligomerized to hexene.…”

Section: Modified Network Including Cracking (Network Ii)mentioning

confidence: 99%

Detailed Kinetic Model for the Reaction of Ethene to Propene on Ni/AlMCM‐41

Felischak

Wolff

Perea

et al. 2020

Chemie Ingenieur Technik

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This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made. Supporting Information available onlineThe Ni/AlMCM-41 was prepared and applied as the catalyst for the direct conversion of ethene to propene. Based on the results of the broad experimental study, two reaction networks were compared, one consisting of dimerization, isomerization and metathesis and a modified network suggesting the cracking of long-chain olefins. To correlate the experimentally obtained data, the classical Langmuir-Hinshelwood-Hougen-Watson model was applied for both reaction networks. The second network involving catalytic cracking offers a satisfying prediction of the observed product distributions.

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Tracing Active Sites in Supported Ni Catalysts during Butene Oligomerization by Operando Spectroscopy under Pressure

Cited by 38 publications

References 20 publications

Oxidative dehydrogenation of ethane on diluted or promoted nickel oxide catalysts: Influence of the promoter/diluter

Oxidative dehydrogenation of ethane on diluted or promoted nickel oxide catalysts: Influence of the promoter/diluter

Influence of Remaining Acid Sites of an Amorphous Aluminosilicate on the Oligomerization of n-Butenes after Impregnation with Nickel Ions

Detailed Kinetic Model for the Reaction of Ethene to Propene on Ni/AlMCM‐41

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