New mechanism insights into methane steam reforming on Pt/Ni from DFT and experimental kinetic study

Niu, Juntian; Wang, Yalan; Qi, Yanying; Dam, Anh Hoang; Wang, Hongmin; Zhu, Yi‐An; Holmén, Anders; Ran, Jingyu; Chen, De

doi:10.1016/j.fuel.2020.117143

Cited by 105 publications

(56 citation statements)

References 72 publications

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“…For all the studied catalyst structures, the Mulliken population analysis was used to estimate the charge on each atom. The adsorption energy of the O‐contained species O 2 *, OOH*, O*, OH*, H 2 O*, and H 2 O 2 * can be calculated by References 30‐32.

E_{ad} = E_{specise/catalyst} - E_{specise} - E_{catalyst}

…”

Section: Computational Approachmentioning

confidence: 99%

Mechanisms of oxygen reduction reaction on B doped FeN ₄ G and FeN ₄ CNT catalysts for proton‐exchange membrane fuel cells

Niu

et al. 2021

Int J Energy Res

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Density functional theory (DFT) was used to calculate the stability, oxygen reduction reaction (ORR) mechanism and activity of B-doped FeN 4 CNT (carbon nano-tube [CNT]) and FeN 4 G (G, graphene). The B-doped catalysts are more stable and active than that of the un-doped, especially for FeN 4 B2 G and FeN 4 B2 CNT. Based on the Mulliken charge and electrostatic potential surface of these catalysts, Fe atom is found to be the most active site for the adsorption of O-contained species. It is shown that their adsorption energies decrease in the range: O > OH > Co-ad OH > OOH > O 2 > H 2 O > H 2 O 2 on these catalysts. H 2 O 2 will be directly dissociated into two co-adsorbed OH* or O* + H 2 O* instead of H 2 O 2 on the graphene series catalysts, and the process of reaction (H 2 O 2 + * ! 2OH*) on the active sites of the CNT series catalysts is strongly exothermic. Hence, desorption of H 2 O 2 * into the solution is difficult to proceed during the oxygen reduction process. All the catalysts are expected to promote a single site four electron process through the reaction path of I (O 2 ! O 2 * ! OOH* ! O* ! OH* ! H 2 O) except for the catalyst of FeN 4 CNT. The rate-determining step (RDS) for ORR process on FeN 4 B2 G is the first reduction step (O 2 * ! OOH*), while the RDS is the fourth reduction step (OH* ! H 2 O) for the other catalysts. FeN 4 B2 G exhibits the largest onset potentials of 0.53 V, which is larger than the on-set potential of un-doped B FeN 4 G catalyst (0.39 V). In addition, the B-doped FeN 4 CNT catalyst shows the better activity compared to the un-doped ones.

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E_{ad} = E_{specise/catalyst} - E_{specise} - E_{catalyst}

…”

Section: Computational Approachmentioning

confidence: 99%

Mechanisms of oxygen reduction reaction on B doped FeN ₄ G and FeN ₄ CNT catalysts for proton‐exchange membrane fuel cells

Niu

et al. 2021

Int J Energy Res

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“…Here, using a combination of ambient-pressure X-ray photoelectron spectroscopy (AP-XPS) and molecular modeling based on density functional theory (DFT), we present a comprehensive study of the MSR reaction on the surface of model Ni/CeO2(111) catalysts and compare with results reported for the extended Ni(111) surface in the literature. [21][22][23][24][47][48][49][50][51][52][53][54] We show that low-loaded Ni/CeO2 catalysts have sites with unique properties that result from the nature of both the metallic phase and the support as well as their interactions, which enable the facile activation of C−H and O−H bonds from CH4 and H2O, respectively. The calculated elementary dehydrogenation and oxidation steps along the MSR reaction reveal that the crucial step is the formation of a COH intermediate via the reaction of carbon atoms with OH groups, suppressing carbon deposition.…”

Section: Introductionmentioning

confidence: 83%

“…19 However, experimental and computational studies have shown that the reactions of carbonaceous species with oxygen to form the C-O bond also involve high energy barriers, and could therefore be rate-controlling. [20][21][22][23][24][25][26] Furthermore, in previous combined computational and in-situ spectroscopic studies, it was shown that well-dispersed small Ni nanoparticles supported on a non-reduced CeO2 surface can in fact activate CH4 at room temperature, with calculated energy barriers up to 80% lower than those for extended nickel surfaces. [27][28][29][30][31] This highlights the need to consider both the effect of the nature of the support and the metal loading to fully understand the mechanism governing the MSR reaction over supported metal catalysts, which is necessary for the development of improved catalytic systems.…”

Section: Introductionmentioning

confidence: 99%

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

Salcedo¹,

Lustemberg²,

Rui³

et al. 2021

Preprint

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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 the 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 CH4/H2O gas mixtures react with Ni/CeO2(111) surfaces to form OH, CHx and CHxO at 300 K. All these species are easy to form and desorb at temperatures below 700 K when the rate of the MSR process accelerates. Density functional theory (DFT) modeling of the reaction over ceria-supported small Ni nanoparticles predicts relatively low activation barriers between 0.3–0.7 eV for the complete dehydrogenation of methane to carbon and the barrierless activation of water at interfacial Ni sites. Hydroxyls resulting from water activation allow 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 are rate-determining steps, and the OH-assisted CO formation through the COH intermediate constitutes a low-barrier pathway that prevents carbon accumulation. The interaction 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 could pave the way for further advances in the design of stable and highly active Ni-based catalysts for hydrogen production.

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“…But the pure metal catalyst cannot meet the demand. Doping noble metals, such as Rh 11‐13 , Pt 14,15 , Pd 16 and else 17 , or non‐noble metals, such as Co 18,19 , Cu 20 , Fe 21,22 and Mg 23 , in another metal to form bimetallic catalyst has been studied extensively in experiments 24 and DFT calculations 25,26 . The energy barrier completely dissociated by CH 4 on the surface of M‐doped Cu(111)(M = Pt, Rh, Ni, Pd) was studied.…”

Section: Introductionmentioning

confidence: 99%

Comparative density functional theory study of carbon formation and removal mechanism on Rh modified Ni‐based catalyst in theCH₄/CO₂reforming

et al. 2021

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Summary Rh catalyst shows promising performance for coke resistance in the CH4/CO2 reforming reaction. In this study, a single atom Rh was added to the surface of Ni(111) by doping and adsorbing ways, and the performance of these surfaces was compared with the pure Ni(111) through density functional theory (DFT) calculation. The reactions related to the carbon formation were studied to obtain the favored adsorption site and dominant reaction paths on three surfaces. A good linear relationship between the charge difference and the reaction barrier was proposed. On the Ni(111) surface, the highest energy barrier of CH* oxidation and decomposition is 1.24 and 1.30 eV, respectively, thus these two reaction paths are dominant. The most favorable pathway for the Rh/Ni(111) is CH* + O* → CHO* → CO* + H*, with the highest energy barrier of 1.34 eV. However, C* is more likely to be converted into C‐C (C2) than oxidized on all three catalyst surfaces. As a result, Rh/Ni(111) surface shows better catalytic activity thermodynamically and more superior carbon deposition resistance. In general, compared with pure Ni catalyst, the modification of Rh could manipulate the reaction path of CH* consumption, which could inhibit the direct decomposition of CH*, and finally suppress the carbon deposition.

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New mechanism insights into methane steam reforming on Pt/Ni from DFT and experimental kinetic study

Cited by 105 publications

References 72 publications

Mechanisms of oxygen reduction reaction on B doped FeN ₄ G and FeN ₄ CNT catalysts for proton‐exchange membrane fuel cells

Mechanisms of oxygen reduction reaction on B doped FeN ₄ G and FeN ₄ CNT catalysts for proton‐exchange membrane fuel cells

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

Comparative density functional theory study of carbon formation and removal mechanism on Rh modified Ni‐based catalyst in theCH₄/CO₂reforming

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New mechanism insights into methane steam reforming on Pt/Ni from DFT and experimental kinetic study

Cited by 105 publications

References 72 publications

Mechanisms of oxygen reduction reaction on B doped FeN 4 G and FeN 4 CNT catalysts for proton‐exchange membrane fuel cells

Mechanisms of oxygen reduction reaction on B doped FeN 4 G and FeN 4 CNT catalysts for proton‐exchange membrane fuel cells

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

Comparative density functional theory study of carbon formation and removal mechanism on Rh modified Ni‐based catalyst in theCH4/CO2reforming

Contact Info

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Mechanisms of oxygen reduction reaction on B doped FeN ₄ G and FeN ₄ CNT catalysts for proton‐exchange membrane fuel cells

Mechanisms of oxygen reduction reaction on B doped FeN ₄ G and FeN ₄ CNT catalysts for proton‐exchange membrane fuel cells

Comparative density functional theory study of carbon formation and removal mechanism on Rh modified Ni‐based catalyst in theCH₄/CO₂reforming