Methane, electrochemical

Maleic acid hydrogenation, 481 Metal-support interactions and electrochemical promotion, 490 and electrophobic reactions, 499 mechanism of, 490 model for, 507 Metcalfe, modeling, 316 Methanation, electrochemical promotion of, 406, 409... 

Chen XJ, Liu QL, Chan SH, Brandon NP, and Khor KA. High performance cathode-supported SOFC with perovskite anode operating in weakly humidified hydrogen and methane. Electrochem. Commun. 2007 9 767-772. 

In a 1999 letter to Nature (Perry Murray etal., 1999), from North Western University, Illinois, the authors record the first laboratory achievement of useful oxidation rates for direct methane electrochemical oxidation, using an IT/SOFC. The cathode structures were porous lanthanum strontium manganite (LSM) on porous ( 203)0.15 (Ce02)o,85 or YDC. The anodes were cermets, porous YSZ with nickel in the pores. The laboratory operating temperatures were in the range 500-700 °C. The account of the North Western work, reporting on new anode types, continues on pp. 921-924 of Williams (2002). 

When this appendix was in preparation, methane electrochemical oxidation had not been achieved. A reformer was essential That fact influenced the author s choice of initial calculation route for the methane chemical exergy, to be via oxidation via an equilibrium reformer. Meanwhile direct oxidation has been achieved in the laboratory, as mentioned in Section A.3.2 (route 1). 

Gaudillere C, VemouxP, FarmssengD (2010) Impact of reforming catalyst on the anodic polarisation resistance in single-chamber SOFC fed by methane. Electrochem Commun 12 1332-1335. doi 10.1016/j. elecom.2010.07.010... 

G. Kim, G. Corre, J.T.S. Irvine, J.M. Vohs, R.J. Gorte, Engineering composite oxide SOFC anodes for efficient oxidation of methane. Electrochem. Solid State Lett. 11, B16-B19 (2008)... 

From this value and known C—H bond dissociation energies, pK values can be calculated. Early application of these methods gave estimates of the p/Ts of toluene and propene of about 45 and 48, respectively. Methane was estimated to have a pAT in the range of 52-62. Electrochemical measurements in DMF have given the results shown in Table 7.3. These measurements put the pK of methane at about 48, with benzylic and allylic stabilization leading to values of 39 and 38 for toluene and propene, respectively. The electrochemical values overlap with the pATdmso scale for compounds such as diphenyl-methane and triphenylmethane. 

I.V. Yentekakis, Y. Jiang, S. Neophytides, S. Bebelis, and C.G. Vayenas, Catalysis, Electrocatalysis and Electrochemical Promotion of the Steam Reforming of Methane over Ni Film and Ni-YSZ cermet Anodes, Ionics 1, 491-498 (1995). 

O.A. Mar ina, V.A. Sobyanin, V.D. Belyaev, and V.N. Parmon, The effect of electrochemical pumping of oxygen on catalytic behaviour of metal electrodes in methane oxidation, in New Aspects of Spillover Effect in Catalysis for Development of Highly Active Catalysts, Stud. Surf. Sci. Catal. 77 (T. Inui, K. Fujimoto, T. Uchijima,... 

Methane oxidation and partial oxidation, electrochemical promotion of, 308 dimerization, 470 reforming, 410 Methanol dehydrogenation electrochemical promotion of, 403 selectivity modification, 404 Methanol oxidation electrochemical promotion of 398 selectivity modification, 400 Microscopy... 

Ohtake, N., and Yashikawa, M., Diamond Film Preparation by Arc Discharge Plasma Jet Chemical Vapor Deposition in the Methane Atmosphere, / Electrochem. Soc., 137(2) 717-722(1990)... 

In the phosphoric acid fuel cell as currently practiced, a premium (hydrogen rich) hydrocarbon (e.g. methane) fuel is steam reformed to produce a hydrogen feedstock to the cell stack for direct (electrochemical) conversion to electrical energy. At the fuel electrode, hydrogen ionization is accomplished by use of a catalytic material (e.g. Pt, Pd, or Ru) to form solvated protons. 

A calculation of the temperature dependence of the free energy for the reactions in Eqs. (15)-(18), and hence the electrochemical potential, showed that with an increase in temperature, formic acid formation became more unfavorable.4 In the case of formaldehyde, methanol, and methane formation, the calculation indicated a positive shift in the reduction potential, but of very small magnitude ca. 30 mV for a temperature change from 300 to 500 K, and ca. 20 mV from 500 to 1200 K.4... 

The stable hydride cluster Pd4(dppm)4(H)3]+ [dppm = bis(diphenylphosphino)methane] can be electrochemically generated from Pd2(dppm)2Cl2] at —1.35 V vs. SCE in DMF containing HC02H (Equations (21) and (22)). Subsequent addition of proton under the same reducing conditions induces dihydrogen evolution.43... 

Fig. 14 Transient absorption spectrum of anthracene cation radical (ANT+ ) obtained upon 30-ps laser excitation of the [ANT, OsOJ charge-transfer complex in dichloro-methane. The inset shows the authentic spectrum of ANT+ obtained by an independent (electrochemical) method. Reproduced with permission from Ref. 96b.

Electropox [Electrochemical partial oxidation] Also called Pox. An electrochemical process for oxidizing methane to syngas. It combines the partial oxidation and steam reforming of methane with oxygen separation in a single stage. Invented in 1988 by T. J. Mazanec at BP Chemicals. An industrial-academic consortium to develop the process was formed in 1997. 

Steele BCH, Kelly I, Middleton PH, and Rudkin R. Oxidation of methane in solid state electrochemical reactors. Solid State Ionics 1988 28 1547-1552. 

Park S, Craciun R, Vohs JM, and Gorte RJ. Direct oxidation of hydrocarbons in a solid oxide fuel cell I. methane oxidation. J Electrochem Soc 1999 146 3603-3605. 

Lee SI, Ahn K, Vohs JM, and Gorte RJ. Cu-Co bimetallic anodes for direct utilization of methane in SOFCs. Electrochem. Solid State Lett. 2005 8 A48-A51. 

Kim H, Lu C, Worrell WL, Vohs JM, and Gorte RJ. Cu-Ni cermet anodes for direct oxidation of methane in solid-oxide fuel cells. J. Electrochem. Soc. 2002 149 A247-A250. 

Mechanistic Aspects of the Electrochemical Reduction of Carbon Monoxide and Methanol to Methane at Ruthenium and Copper Electrodes... 

The electrochemical reductions of carbon monoxide and methanol to methane (Equations 1 and 2) have potentials, under standard conditions, of +0.019 and +0.390 V vs SCE respectively (or a... 

Table II. The Effect of CO on the Electrochemical Reduction of CO2 to Methane at Electroplated Ru Electrodes a...

Phenylthio-l-trimethylsilylalkanes are easily prepared by the alkylation of (phenylthioXtrimethylsilyl)mcthane as shown in Scheme 10 [40], The treatment of (phenylthio)(trimethylsilyl)methane with butyllithium/tetramethylethylene-diamine (TMEDA) in hexane followed by the addition of alkyl halides or epoxides produces alkylation products which can be oxidized electrochemically to yield the acetals. Since acetals are readily hydrolyzed to aldehydes, (phenylthioXtrimethylsilyl)methane provides a synthon of the formyl anion. This is an alternative to the oxidative transformation of a-thiosilanes to aldehydes via Sila-Pummerer rearrangement under application of MCPBA as oxidant [40, 41]. 

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