Redox and Catalytic Properties of Promoted NiO Catalysts for the Oxidative Dehydrogenation of Ethane

“…We can mention metal oxide promoters as in the case of WO3-NiO [11,12], CeO2-NiO [13], ZrO2-NiO [14], and Ta2O5-NiO [15] catalysts. The use of Sn [16,17] and, especially, Nb [18][19][20][21][22] as promoters of NiO leads to the best catalytic performance, achieving high selectivity to ethylene at moderate and high ethane conversions. In these promoted catalysts, mainly prepared by mixing solutions of the corresponding nickel and promoter salts, the formation of solid solutions and/or the partial incorporation of the promoter into the NiO lattice is favored.…”

Section: Introductionmentioning

confidence: 99%

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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“…Since the presence or absence of oxygen in the feed can have a great influence in the catalytic performance when dealing with gas-phase partial oxidation reactions [42], we have conducted anaerobic catalytic tests on W-Ti-O catalysts (Fig. 8 and Fig.…”

Section: Anaerobic Transformation Of Methanol On W-ti-o Catalystsmentioning

confidence: 99%

Tungsten-titanium mixed oxide bronzes: Synthesis, characterization and catalytic behavior in methanol transformation

Delgado

Soriano

Solsona

et al. 2019

Applied Catalysis A: General

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Tungsten oxide bronze-based materials show extremely adaptive structural and compositional features that make them suitable for functional properties modulation. Herein we report the preparation of a series of Ti-containing tungsten oxide catalysts presenting a hexagonal tungsten bronze-type structure. The insertion of Ti 4+ within the structure (likely in the octahedral framework of the hexagonal tungsten bronze) leads to an increase in the number of strong acid sites, and the disappearance of W 5+ surface species found in the undoped tungsten oxide. With the aim of studying the acid-redox properties of the titled catalysts, the catalytic transformation of methanol has been carried out in the presence and the absence of O2 in the feed. Both catalytic activity and the acidredox properties of these catalysts are highly dependent on catalyst composition and reaction conditions applied (i.e. in the presence or in the absence O2 in the feed). Aerobic experiments show the depletion of the redox functionality (i.e. no formaldehyde detected in the products) when Ti 4+ is incorporated in the framework (i.e. 100 % selectivity to dimethyl ether). On the other hand, all the catalysts show the loss of the redox function and a decrease in the catalytic activity when anaerobic conditions are used. In the absence of oxygen, the catalysts are still active in the dehydration of methanol to dimethyl ether, i.e. they maintain their acid functionality even when oxygen is not present in the feed. The results are discussed in terms of the available surface active sites present in each case.

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Redox and Catalytic Properties of Promoted NiO Catalysts for the Oxidative Dehydrogenation of Ethane

Cited by 38 publications

References 39 publications

Accelerated active phase transformation of NiO powered by Pt single atoms for enhanced oxygen evolution reaction

Accelerated active phase transformation of NiO powered by Pt single atoms for enhanced oxygen evolution reaction

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

Tungsten-titanium mixed oxide bronzes: Synthesis, characterization and catalytic behavior in methanol transformation

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