Catalytic activity of carbons for methane decomposition reaction

Muradov, Nazim; Smith, Franklyn; T‐Raissi, Ali

doi:10.1016/j.cattod.2005.02.018

Cited by 386 publications

(264 citation statements)

References 16 publications

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“…Couttenye et al (2005) found an increase of activity with increasing size of NiO crystallites. In addition carbons are also active in CH 4 thermal decomposition (Muradov et al, 2005). Given the absence of H 2 in the reactor effluent despite its short retention time, any hydrogen produced via thermal decomposition was therefore assumed to be entirely consumed by the OTM reduction reaction (R2.5), also creating water as a co-product.…”

Section: Results Under Ch 4 /N 2 /Steam(fuel) Feed and Discussionmentioning

confidence: 99%

Production of hydrogen by unmixed steam reforming of methane

Dupont

Ross

Knight

et al. 2008

Chemical Engineering Science

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Unmixed steam reforming is an alternative method of catalytic steam reforming that uses separate air and fuel-steam feeds, producing a reformate high in H 2 content using a single reactor and a variety of fuels. It claims insensitivity to carbon formation and can operate autothermally. The high H 2 content is achieved by in-situ N 2 separation from the air using an oxygen transfer material (OTM), and by CO 2 capture using a solid sorbent. The OTM and CO 2 sorbent are regenerated during the fuel-steam feed and the air feed respectively within the same reactor. This paper describes the steps taken to choose a suitable CO 2 -sorbent material for this process when using methane fuel with the help of micro reactor tests, and the study of the carbonation efficiency and regeneration ability of the materials tested. Elemental balances from bench scale experiments using the best OTM in the absence of the CO 2 sorbent allow identifying the sequence of the chemical reaction mechanism. The effect of reactor temperature between 600 and 800°C on the process outputs is investigated. Temperatures of 600°C and 800°C under the fuel-steam feed were each found to offer a different set of desirable outputs. Two stages during the fuel-steam feed were characterised by a different set of global reactions, an initial stage where the OTM is reduced directly by methane, and indirectly by hydrogen produced by methane thermal decomposition, in the second stage, steam reforming takes over once sufficient OTM has been reduced. The implications of these stages on the process desirable outputs such as efficiency of reactants conversion, reformate gas quality, and transient effects are discussed.

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Section: Results Under Ch 4 /N 2 /Steam(fuel) Feed and Discussionmentioning

confidence: 99%

Production of hydrogen by unmixed steam reforming of methane

Dupont

Ross

Knight

et al. 2008

Chemical Engineering Science

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“…At low-P, for industrial applications the methane-carbon interaction has been investigated as a pathway for hydrogen production (18,19). For example, at atmospheric pressure and temperatures between 1,023 and 1,173 K methane is known to react with coal (lignite, anthracite) forming molecular hydrogen, carbon [predominantly in graphitelike forms (20)] and a small amount of hydrocarbons (0.1%) (18).…”

mentioning

confidence: 99%

“…For example, at atmospheric pressure and temperatures between 1,023 and 1,173 K methane is known to react with coal (lignite, anthracite) forming molecular hydrogen, carbon [predominantly in graphitelike forms (20)] and a small amount of hydrocarbons (0.1%) (18). The active sites for the dehydrogenation mechanism have been identified as defects at the surface (19,21). An increase in the chemical activity of C-H-O fluids was also observed in recent DAC experiments at upper mantle conditions (22) in the presence of graphite.…”

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confidence: 99%

Stability of hydrocarbons at deep Earth pressures and temperatures

Spanu

Donadio

Hohl

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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Determining the thermochemical properties of hydrocarbons (HCs) at high pressure and temperature is a key step toward understanding carbon reservoirs and fluxes in the deep Earth. The stability of carbon-hydrogen systems at depths greater than a few thousand meters is poorly understood and the extent of abiogenic HCs in the Earth mantle remains controversial. We report ab initio molecular dynamics simulations and free energy calculations aimed at investigating the formation of higher HCs from dissociation of pure methane, and in the presence of carbon surfaces and transition metals, for pressures of 2 to 30 GPa and temperatures of 800 to 4,000 K. We show that for T ≥ 2,000 K and P ≥ 4 GPa HCs higher than methane are energetically favored. Our results indicate that higher HCs become more stable between 1,000 and 2,000 K and P ≥ 4 GPa. The interaction of methane with a transition metal facilitates the formation of these HCs in a range of temperature where otherwise pure methane would be metastable. Our results provide a unified interpretation of several recent experiments and a detailed microscopic model of methane dissociation and polymerization at high pressure and temperature.carbon cycle | Earth interior | numerical simulation T here is growing evidence that carbon-bearing compounds in the deep Earth contribute to the global carbon cycle (1, 2). We have limited knowledge of the role played by pressure and temperature on reactions in the C-O-H system under these conditions. In the case of methane, many open questions remain concerning its dissociation and possible polymerization under pressure, in spite of several experiments carried out in recent years (3-6).Laboratory experiments indicate that methane can form under P-T conditions of the Earth's upper mantle through carbonate reduction processes (7). For T > 1;000 K and P ¼ 4-5 GPa, thermochemical models (8) predict that methane is less stable than complex mixtures of hydrocarbons (HCs) (e.g., ethane, propane, etc.), although there is no general consensus on the temperature and pressure conditions at which dissociation and polymerization processes begin. Experiments have not yet probed the microscopic mechanisms leading to dehydrogenation of methane under pressure and formation of higher hydrocarbons.Laser-heated diamond anvil cell (DAC) experiments (3) indicate the formation of both HCs and diamond at 19 GPa and 2,000-3,000 K. These results are consistent with those of shock compression studies (9), suggesting dissociation of methane and diamond formation at 20 GPa and 2,000 K. Recent Raman measurements (6) support the formation of ethane, propane, and butane upon methane compression, in a range of pressure and temperature compatible with upper mantle conditions, i.e., P ≃ 2-5 GPa and T ≃ 1;000-1;500 K. Ethane was also found as a reaction product in a DAC experiment (5) at T > 1;100 K and P > 10 GPa. All experimental results to date indicate that heavier hydrocarbons form upon compression of methane (3-6).To investigate the relative stability of methane and ...

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“…The first step was ascribed to the induction period that was mentioned above. In the second step, methane conversion showed a slow decrease with the reaction time, which may be due to inactive carbon deposits [22,24] produced during CMD which covered the Fe active sites, although the catalysts were not completely deactivated. In the third step, methane conversion showed a quick increase with the reaction time and stably continued to increase, which indicated that some other factors besides Fe played a role in improving methane conversion during this time.…”

Section: Catalytic Methane Decompositionmentioning

confidence: 99%

“…Many works have been reported on CMD using metal catalysts, such as Fe [12][13][14][15], Co [16,17], Ni [18][19][20][21], carbon materials [22][23][24][25][26][27], 2 Journal of Nanomaterials three red mud samples for hydrogen production by CMD. The highest methane conversion obtained in their study was 19.8% with a corresponding methane conversion rate of 18.0 × 10 −6 mol CH 4 /g cat /s, which is associated with a sample containing the highest proportion of iron, and two other samples exhibited poorer activity than this sample did.…”

Section: Introductionmentioning

confidence: 99%

Preparation of Modified Red Mud-Supported Fe Catalysts for Hydrogen Production by Catalytic Methane Decomposition

Liu

Fang

et al. 2017

Journal of Nanomaterials

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A modified red mud-(MRM-) supported Fe catalyst ( Fe/MRM) was prepared using the homogeneous precipitation method and applied to methane decomposition to produce hydrogen. The TEM and SEM-EDX results suggested that the particle sizes of the Fe/MRM catalysts were much smaller than that of raw red mud (RM), and the active metal Fe was evenly distributed over the catalyst structure. Moreover, BET results indicated that the surface areas and pore volumes of the catalysts were significantly improved, and the pore sizes of Fe/MRM were distributed from 5 to 12 nm, which is typical for a mesoporous material. The activities of those catalysts for the catalytic decomposition of methane were studied at atmospheric pressure at a moderate temperature of 650 ∘ C; the results showed that the Fe/MRM catalysts were more active than RM and MRM. The methane conversion curves of Fe/MRM catalysts exhibited similar variation tendencies (three-step) during the reaction despite different Fe contents, and the loading amount of Fe clearly affected the activity of the catalysts.

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Catalytic activity of carbons for methane decomposition reaction

Cited by 386 publications

References 16 publications

Production of hydrogen by unmixed steam reforming of methane

Production of hydrogen by unmixed steam reforming of methane

Stability of hydrocarbons at deep Earth pressures and temperatures

Preparation of Modified Red Mud-Supported Fe Catalysts for Hydrogen Production by Catalytic Methane Decomposition

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