Direct Oxidation of Methane to Methanol at Low Temperature and Pressure in an Electrochemical Fuel Cell

Tomita, Atsuko; Nakajima, Junya; Hibino, Takashi

doi:10.1002/anie.200703928

Cited by 98 publications

(66 citation statements)

References 21 publications

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“…at intermediate temperatures (373-573 K) [7][8][9][10][11][12][13][14][15][16][17][18][19][20]. Hibino et al reported that SnP 2 O 7 and Sn 0.9 In 0.1-P 2 O 7 exhibit high protonic conductivities of above 10 − 2 S cm − 1 from 348 to 573 K and above 10 − 1 S cm − 1 from 398 to 573 K under unhumidified conditions, respectively [7,8].…”

Section: Introductionmentioning

confidence: 96%

Ionic conduction in undoped SnP2O7 at intermediate temperatures

Wang¹,

Xiao²,

Zhou³

et al. 2010

Solid State Ionics

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Section: Introductionmentioning

confidence: 96%

Ionic conduction in undoped SnP2O7 at intermediate temperatures

Wang¹,

Xiao²,

Zhou³

et al. 2010

Solid State Ionics

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“…Nagao et al reported that the conductivities of AP 2 O 7 (A = Sn, Ti, Ge, Si) increased in the order of Ge 4+ < Si 4+ < Ti 4+ < Sn 4+ in unhumidified air [9], and that proton-conducting Sn 1−x R x P 2 O 7 (R = Al 3+ , In 3+ ) were also applied to some electrochemical reactors, such as H 2 /air fuel cell, selective catalytic reduction of NO x , direct oxidation of methane to methanol, and gas sensors, etc. [13][14][15][16][17][18]. Chen et al reported that Sn 0.9 In 0.1 P 2 O 7 can conduct both protons and oxide-ions in the temperature range from 403 to 503 K [19].…”

Section: Introductionmentioning

confidence: 98%

Ionic conduction in Sn1−xScxP2O7 for intermediate temperature fuel cells

Wang

Zhang

Guo-xian

et al. 2011

Journal of Power Sources

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“…Previously, a number of catalytic systems have also been developed for methane oxidation. [12][13][14][15] They all function at high temperatures and several are heterogeneous systems operating in zeolites. [16][17][18] Our biomimetic tricopper complex oxidizes methane efficiently at room temperature and can be formulated either as a homogeneous or heterogeneous catalyst.…”

mentioning

confidence: 99%

Efficient Oxidation of Methane to Methanol by Dioxygen Mediated by Tricopper Clusters

et al. 2013

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Methane oxidation is extremely difficult chemistry to perform in the laboratory. The CÀH bond in CH 4 has the highest bond energy (104 kcal mol À1 ) amongst organic substrates. In nature, the controlled oxidation of organic substrates is mediated by an important class of enzymes known as monooxygenases and dioxygenases, [1] and the methane monooxygenases are unique in their capability to mediate the facile conversion of methane to methanol. [2,3] With a turnover frequency approaching 1 s À1 , the particulate methane monooxygenase (pMMO) is the most efficient methane oxidizer discovered to date. Given the current interest in developing a laboratory catalyst suitable for the conversion of methane to methanol on an industrial scale, there is strong impetus to understand how pMMO works and to develop functional biomimetics of this enzyme. pMMO is a complex membrane protein consisting of three subunits (PmoA, PmoB, and PmoC) and many copper cofactors. [3] Inspired by the proposal that the catalytic site might be a tricopper cluster, we have recently developed a series of tricopper complexes that are capable of supporting facile catalytic oxidation of hydrocarbons. [4,5] We show herein that these model tricopper complexes can mediate efficient catalytic oxidation of methane to methanol as well.The oxidation of CH 4 mediated by the tricopper complex [Cu I Cu I Cu I (7-N-Etppz)] 1+ in acetonitrile (ACN), where 7-N-Etppz corresponds to the ligand 3,3'-(1,4-diazepane-1,4diyl)bis[1-(4-ethylpiperazine-1-yl)propan-2-ol], is summarized in Figure 1 A. A single turnover (turnover number; TON = 0.92) is obtained when this Cu I Cu I Cu I complex is activated by excess dioxygen in the presence of excess CH 4 (Figure 1 B). The reaction is complete within ten minutes, clearly indicating that the oxidation is very rapid. In accordance with the single turnover, the kinetics of the overall process is pseudo first-order with respect to the concentration of the fully reduced tricopper complex with a rate constant k 1 = 0.065 min À1 (Figure 1 B, inset). If we assume that the kinetics is limited by the dioxygen activation of the Cu I Cu I Cu I cluster with the subsequent O-atom transfer to the substrate molecule being rapid, then k 1 = k 2 ·[O 2 ] 0 , and from the solubility of oxygen in ACN at 25 8C (8.1 mm), [6] we obtain the bimolecular rate constant k 2 of 1.33 10 À1 m À1 s À1 for the dioxygen activation of the Cu I Cu I Cu I cluster. This second-order rate constant is similar to values that we have previously determined for the dioxygen activation of other model tricopper clusters at room temperature. [7,8] The process can be made catalytic by adding the appropriate amounts of H 2 O 2 to regenerate the spent catalyst after O-atom transfer from the activated tricopper complex to CH 4 . This multiple-turnover reaction is depicted in Figure 1 C. In these experiments, the [Cu I Cu I Cu I (7-N-Etppz)] 1+ catalyst is activated by O 2 as in the single-turnover experiment described earlier, but the spent catalyst is regenerated by twoelectron ...

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Direct Oxidation of Methane to Methanol at Low Temperature and Pressure in an Electrochemical Fuel Cell

Abstract: Fuel for thought? The direct oxidation of methane to methanol occurs at atmospheric pressure between 50 and 250 °C in a fuel‐cell‐type reactor (see picture). The efficiency of the electrochemical activation of oxygen is higher than that for the catalytic activation of oxygen.

Cited by 98 publications

References 21 publications

Ionic conduction in undoped SnP2O7 at intermediate temperatures

Ionic conduction in undoped SnP2O7 at intermediate temperatures

Ionic conduction in Sn1−xScxP2O7 for intermediate temperature fuel cells

Efficient Oxidation of Methane to Methanol by Dioxygen Mediated by Tricopper Clusters

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