A mechanistic study of the interactions between methane and nickel supported on doped ceria

Ouyang, Mengzheng; Boldrin, Paul; Maher, Robert C.; Chen, Xiaolong; Liu, Xinhua; Cohen, L. F.; Brandon, Nigel P.

doi:10.1016/j.apcatb.2019.02.038

Cited by 50 publications

(38 citation statements)

References 55 publications

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“… 27 , 28 , 30 , 35 , 36 Furthermore, the easier reducibility of the ceria support allows it to act as an oxygen reservoir, 37 providing unique reaction pathways such as the reverse spillover of oxygen from ceria to metal sites, which has been experimentally observed for a variety of ceria-supported metal catalysts, including Ni/CeO 2 . 38 − 43 Therefore, the observed superior decoking activity of ceria-supported Ni catalysts for MSR could be ascribed to a mechanism involving the oxygen supply from the support promoting carbon removal as CO, 44 , 45 in which the role of water as one of the reactants would be the refilling of the oxygen vacancies generated in the reverse spillover step. However, water-mediated carbon removal has also been discussed in the context of steam reforming of CH 4 .…”

Section: Introductionmentioning

confidence: 99%

Reaction Pathway for Coke-Free Methane Steam Reforming on a Ni/CeO₂ Catalyst: Active Sites and the Role of Metal–Support Interactions

et al. 2021

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Methane steam reforming (MSR) plays a key role in the production of syngas and hydrogen from natural gas. The increasing interest in the use of hydrogen for fuel cell applications demands development of catalysts with high activity at reduced operating temperatures. Ni-based catalysts are promising systems because of their high activity and low cost, but coke formation generally poses a severe problem. Studies of ambient-pressure X-ray photoelectron spectroscopy (AP-XPS) indicate that CH 4 /H 2 O gas mixtures react with Ni/CeO 2 (111) surfaces to form OH, CH x , and CH x O at 300 K. All of these species are easy to form and desorb at temperatures below 700 K when the rate of the MSR process is accelerated. Density functional theory (DFT) modeling of the reaction over ceria-supported small Ni nanoparticles predicts relatively low activation barriers between 0.3 and 0.7 eV for complete dehydrogenation of methane to carbon and the barrierless activation of water at interfacial Ni sites. Hydroxyls resulting from water activation allow for CO formation via a COH intermediate with a barrier of about 0.9 eV, which is much lower than that through a pathway involving lattice oxygen from ceria. Neither methane nor water activation is a rate-determining step, and the OH-assisted CO formation through the COH intermediate constitutes a low-barrier pathway that prevents carbon accumulation. The interactions between Ni and the ceria support and the low metal loading are crucial for the reaction to proceed in a coke-free and efficient way. These results pave the way for further advances in the design of stable and highly active Ni-based catalysts for hydrogen production.

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Section: Introductionmentioning

confidence: 99%

Reaction Pathway for Coke-Free Methane Steam Reforming on a Ni/CeO₂ Catalyst: Active Sites and the Role of Metal–Support Interactions

et al. 2021

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“…[28] There is a variety of other recent literature showing methane partial oxidation to methanol, syngas, or other products. [29][30][31][32][33][34][35][36][37][38][39][40][41][42][43] Our work on the partial oxidation of methane has focused on the search for processes efficient under less acidic environments, in particular trifluoroacetic acid (TFAH). [44] For instance, we have characterized a number of rhodium complexes with C-H activation ability in TFAH.…”

Section: Introductionmentioning

confidence: 99%

DFT Mechanistic Study of Methane Mono-Esterification by Hypervalent Iodine Alkane Oxidation Process

Nielsen

Liebov

et al. 2019

J. Phys. Chem. C

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Recent experiments report high yield (up to 40%) and selectivity (generally > 85%) for the direct partial oxidation of methane to methyl trifluoroacetate in trifluoroacetic acid solvent using hypervalent iodine as the oxidant and in the presence of substoichiometric amounts of chloride anion. We develop here the reaction mechanism for these results based on DFT calculations at the M06-2X/6-311G**++/aug-pVTZ-PP level of plausible intermediates and transition states. We find a mechanistic process that explains both reactivity as well as selectivity of the system. In this oxy-esterification (OxE) system IO 2 Cl 2 − and/or IOCl 4 − act as key transient intermediates, leading to the generation of the high-energy radicals IO 2 • and Cl• that mediate methane C-H bond cleavage. These studies suggest new experiments to validate the OxE mechanism.

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“…The following trend with respect to their activity has been reported: Ni > Co > Fe [57,60,61,[65][66][67]. Nickel-containing catalysts have been extensively investigated since Ni is considered the most active metal for this process [68,69]. However, nickel-based catalysts deactivate rapidly at temperatures above 600°C because the active metal sites are encapsulated within the carbon formed during the reaction [20,27,57,60,66,[70][71][72][73][74].…”

Section: Metal Catalystsmentioning

confidence: 99%

Methane Pyrolysis for CO₂‐Free H₂ Production: A Green Process to Overcome Renewable Energies Unsteadiness

Sanchez‐Bastardo

Schlögl

Ruland

2020

Chemie Ingenieur Technik

134

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The Carbon2Chem® project aims to convert exhaust gases from the steel industry into chemicals such as methanol to reduce CO2 emissions. Here, H2 is required for the conversion of CO2 into methanol. Although much effort is put to produce H2 from renewables, the use of fossil fuels, especially natural gas, seems to be fundamental in the short term. For this reason, the development of clean technologies for the processing of natural gas with a low environmental impact has become a topic of utmost importance. In this context, methane pyrolysis has received special attention to produce CO2‐free H2.

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A mechanistic study of the interactions between methane and nickel supported on doped ceria

Cited by 50 publications

References 55 publications

Reaction Pathway for Coke-Free Methane Steam Reforming on a Ni/CeO₂ Catalyst: Active Sites and the Role of Metal–Support Interactions

Reaction Pathway for Coke-Free Methane Steam Reforming on a Ni/CeO₂ Catalyst: Active Sites and the Role of Metal–Support Interactions

DFT Mechanistic Study of Methane Mono-Esterification by Hypervalent Iodine Alkane Oxidation Process

Methane Pyrolysis for CO₂‐Free H₂ Production: A Green Process to Overcome Renewable Energies Unsteadiness

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A mechanistic study of the interactions between methane and nickel supported on doped ceria

Cited by 50 publications

References 55 publications

Reaction Pathway for Coke-Free Methane Steam Reforming on a Ni/CeO2 Catalyst: Active Sites and the Role of Metal–Support Interactions

Reaction Pathway for Coke-Free Methane Steam Reforming on a Ni/CeO2 Catalyst: Active Sites and the Role of Metal–Support Interactions

DFT Mechanistic Study of Methane Mono-Esterification by Hypervalent Iodine Alkane Oxidation Process

Methane Pyrolysis for CO2‐Free H2 Production: A Green Process to Overcome Renewable Energies Unsteadiness

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Reaction Pathway for Coke-Free Methane Steam Reforming on a Ni/CeO₂ Catalyst: Active Sites and the Role of Metal–Support Interactions

Reaction Pathway for Coke-Free Methane Steam Reforming on a Ni/CeO₂ Catalyst: Active Sites and the Role of Metal–Support Interactions

Methane Pyrolysis for CO₂‐Free H₂ Production: A Green Process to Overcome Renewable Energies Unsteadiness