The electrochemistry of molten K2S2O7 + K2SO4 + V2O5 electrolytes

Franke, Mark; Winnick, Jack

doi:10.1016/0022-0728(87)85172-0

Cited by 18 publications

(14 citation statements)

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“…and earlier primarily electrochemical 5,6,11,18,19 and NMR [20][21][22][23] investigations have pointed to the presence of monomeric and/ or dimeric V(V) complexes formed in the melts at relatively low concentrations of V(V) (as in the present work), and polymeric V(V) complexes at higher mole fractions of V 2 O 5 , i.e., > ∼0.33.…”

Section: Resultsmentioning

confidence: 90%

Sulfato Complex Formation of V(V) and V(IV) in Pyrosulfate Melts Investigated by Potentiometry and Spectroscopic Methods

1999

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By combined potentiometric, electron paramagnetic resonance (EPR), and visible/near-infrared spectroscopic measurements, the coordination of SO 4 2-to V(IV) and V(V) in M 2 S 2 O 7 -M 2 SO 4 -V 2 O 5 (M ) K and Cs) melts, respectively, under SO 2 (g) and O 2 (g) atmospheres at 450-470°C has been investigated. The results for both systems are in accordance with the oxo sulfato vanadate equilibria VO(SO 4 ) 2 2-+ SO 4 2-a VO(SO 4 ) 3 4-for V(IV), (VO) 2 O(SO 4 ) 4 4-+ 2SO 4 2-a 2VO 2 (SO 4 ) 2 3-+ S 2 O 7 2-for V(V), and 2VO 2 (SO 4 ) 2 3-+ SO 2 + SO 4 2-a 2VO(SO 4 ) 3 4-for the V(V)-V(IV) redox reaction in melts saturated with sulfate. Constants for these equilibria have also been obtained, as well as characteristic EPR parameters and molar absorptivities for the complexes. In addition, the mole fractions of M 2 SO 4 in the M 2 S 2 O 7 -M 2 SO 4 /SO 2 (g) systems saturated with M 2 SO 4 were found to be 0.050 19 for M ) K at 450°C and 0.070 02 for M ) Cs at 470°C, respectively.

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Section: Resultsmentioning

confidence: 90%

Sulfato Complex Formation of V(V) and V(IV) in Pyrosulfate Melts Investigated by Potentiometry and Spectroscopic Methods

1999

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“…The effect of increasing sulfate is, as expected from Eq. These tests, being quite extensive, are reported elsewhere (15). Note that the concentration term accounts for about 1.5V.…”

Section: Resultsmentioning

confidence: 89%

“…[5] toward those which favor sulfur dioxide evolution, Eq. Added sulfate reduces the acidity of the melt and helps neutralize the sulfur dioxide, possibly through formation of dithionate SO2 + SO42-= $2062- [15] which can disproportionate to $2062 = SOa 2 + SOa [16] with the sulfur trioxide quickly neutralized by any available sulfate Added sulfate reduces the acidity of the melt and helps neutralize the sulfur dioxide, possibly through formation of dithionate SO2 + SO42-= $2062- [15] which can disproportionate to $2062 = SOa 2 + SOa [16] with the sulfur trioxide quickly neutralized by any available sulfate…”

Section: Discussionmentioning

confidence: 99%

Electrochemical Flue Gas Desulfurization: Reactions in a Pyrosulfate‐Based Electrolyte

Scott¹,

Fannon²,

Winnick³

1988

J. Electrochem. Soc.

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A new electrolyte has been found suitable for use in an electrochemical membrane cell for flue gas desulfurization (FGD). The electrolyte is primarily K2SaO7 and K2SO4, with V2Os as oxidation enhancer. This electrolyte has a melting point near 300~ which is compatible with flue gas exiting the economizer of coal-burning power plants. Standard electrochemical tests have revealed high exchange current densities, around 30 mA/cm 2, in the free electrolyte. Sulfur dioxide is found to be removed from simulated flue gas in a multiple-step process, the first of which is electrochemical reduction of pyrosulfate.

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“…or an electrochemical reaction The chemical equilibrium established in Equation (47) shows the dependence of the concentration of sulfate in the melt on the partial pressure of So, over the melt. At just over 400" C, the equilibrium will be established between sulfate and pyrosulfate.…”

Section: + 2 [~O-v204-3s031 * 2 [Ando-v205-2s031 + 2s03mentioning

confidence: 99%

High-temperature membranes for H{sub 2}S and SO{sub 2} separations. Final report

Winnick¹

1995

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ASTER DISCLAIMERThis report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any wananty, express or implied, or assumes any legal liability orresponsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or p m e s disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, pmcess. or service by trade m e , trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United St@& Government or any agency thereof. The views and opinions of authos expressed herein do not neceSSarily state or reflect those of the United States Govemment or any agency thereof.This report has been reproduced diiectly from the best available copy.Available to DOE List of Tables EXECUTIVE SUMMARYElectrochemical cells which separate H,S and So, from hot gas streams have two important materials issues that limit their successful industrial applicatioq: (1) membranes and (2) electrodes. These were the focus of the present study.For the H,S work, experimental analysis incorporated several membrane and electrode materials; densified zirconia provided the best matrices for entrainment of electrolytic species, ionic mobility, and a process-gas barricade hindering the capabilities of gas cross-over, alternate reactions. In-lab densification of a zirconia weave/knit mat using submicron particles of zirconia in an aqueous suspension provided the most efficient and ckonomical manufacturing technique. Electrode materials of lithiated Ni converted to NiO in-situ were successful in polishing applications; however H,S levels > 100 ppm converted the NiO cathode to a molten nickel sulfide necessitating the use of Co. Lithiated NiO for the anode material remained morphologically stable and conductive in all experimentation. High temperature electrochemical removal of H, S from coal gasification streams has been shown on the bench scale level at the Georgia Institute of Technology utilizing the aforementioned materials. Experimental removals from 1000 pprn to 100 pprn H,S and 100 pprn to 10 pprn H,S proved over 90% removal with applied aprent was economically feasible due to high current efficiencies (-100%) and low polarizations; therefore low power requirements for removal applications in the above ranges.Polishing of H,S from 10 ppm to e 1 ppm tested the most stringent application of the electrochemical cell due to the low concentration of H2S compared to CO,. Removals over 90% were achieved; power requirements for this level of removal are negligible.For the SO2 work, an extensive search was conducted for a suitable membrane material for use in the So, removal system. The most favorable material found was Si,N, proven to be more efficient than other possible mater...

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The electrochemistry of molten K2S2O7 + K2SO4 + V2O5 electrolytes

Cited by 18 publications

References 14 publications

Sulfato Complex Formation of V(V) and V(IV) in Pyrosulfate Melts Investigated by Potentiometry and Spectroscopic Methods

Sulfato Complex Formation of V(V) and V(IV) in Pyrosulfate Melts Investigated by Potentiometry and Spectroscopic Methods

Electrochemical Flue Gas Desulfurization: Reactions in a Pyrosulfate‐Based Electrolyte

High-temperature membranes for H{sub 2}S and SO{sub 2} separations. Final report

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